DELIVERY DEVICE COMPRISING A SIDE CHANNEL BLOWER OR PERIPHERAL BLOWER

Abstract

A delivery device for a medium to be delivered, for example for purging a filter for volatile fuel components, including a blower, which is embodied as a side channel blower or peripheral blower, and optionally an electric drive motor for the blower. The blower including: a housing, including: an inlet and an outlet for the medium to be delivered, for example purge air; a delivery channel which extends in the circumferential direction and has a side channel; and an interrupter channel which extends in the circumferential direction for separating the inlet and the outlet; and an impeller which can rotate in the housing about a rotational axis and includes paddles which, when the impeller is rotated, pass through the delivery channel and the interrupter channel. The delivery device is configured such that the delivery-pressure-over-delivery-flow characteristic curve of the delivery device or the blower flattens or drops towards minimum delivery flow.

Claims

1. A delivery device for a medium to be delivered, for purging a filter for volatile fuel components, comprising a blower, which is embodied as a side channel blower or peripheral blower, and optionally an electric drive motor for the blower, the blower comprising: 1.1 a housing, comprising: an inlet and an outlet for the medium to be delivered; a delivery channel which extends in the circumferential direction and comprises a side channel; and an interrupter channel which extends in the circumferential direction for separating the inlet and the outlet; and 1.2 an impeller adapted to rotate in the housing about a rotational axis and comprises paddles which, when the impeller is rotated, pass through the delivery channel and the interrupter channel, 1.3 wherein the delivery device is configured such that the delivery-pressure-over-delivery-flow characteristic curve of the delivery device or the blower flattens or drops towards minimum delivery flow.

2. The delivery device according to claim 1, wherein the paddles and the interrupter channel form an axial sealing gap along the axially outer edge of the paddle on one or both end-facing sides of the respective paddle, exhibiting an axial gap width which is constant or increases only monotonically and progressing radially, and a radial sealing gap exhibiting a radial gap width along the radially outer edge of the respective paddle, over the angular extent of the interrupter channel, wherein the axial gap width and/or the radial gap width is/are of a size such that a specific leakage via the interrupter channel is established and the delivery-pressure-over-delivery-flow characteristic curve flattens or drops towards minimum delivery flow.

3. The delivery device according to claim 2, wherein the axial gap width and/or the radial gap width is/are constant along one of both end-facing sides and/or along the outer circumference of the respective paddle or increases only monotonically or decreases only monotonically along the respective sealing gap.

4. The delivery device according to claim 1, wherein the impeller and the interrupter channel limit an axial sealing gap over the angular extent of the interrupter channel, in order to seal off the interrupter channel towards the radially outer side, and said axial sealing gap widens axially at a base point of the paddle or on the radially outer side of the base point of the paddle on the axially outer edge of the respective paddle, such that an increased axial sealing gap between the respective paddle and the interrupter channel is obtained.

5. The delivery device according to claim 1, wherein: the impeller comprises an outer circumference from which the paddles protrude radially outwards; the paddles each comprise an outer edge which extends from an axially left-hand base point of the paddle on the outer circumference of the impeller up to an axially right-hand base point of the paddle on the outer circumference of the impeller via a radially outer circumference of the respective paddle; the interrupter channel and the respective paddle form a sealing gap which extends around the outer edge of the paddle from the left-hand base point of the paddle up to the right-hand base point of the paddle; the sealing gap exhibits an area, as projected into a longitudinal sectional plane of the impeller in the rotational direction of the impeller, wherein the rotational axis of the impeller extends in this longitudinal sectional plane; the respective paddle exhibits an effective area, as projected into said longitudinal sectional plane in the rotational direction; and a ratio between the area of the sealing gap and the effective area of the paddle measures at least 0.06 or at least 0.07 or at least 0.08.

6. The delivery device according to claim 1, wherein the paddles comprise a convex rounded profile or an oblique chamfer, which extends in the circumferential direction, on at least one axially outer edge of the paddle and/or on the radially outer edge of the paddle.

7. The delivery device according to claim 1, wherein several or all of the paddles comprise a radially outer edge which in a plan view onto a front side of the respective paddle is convexly or concavely arched radially inwards or radially outwards proceeding from both axial end-facing sides or is polygonal.

8. The delivery device according to claim 7, wherein the radially outer edge is roundly arched radially inwards in the plan view onto the front side of the respective paddle.

9. The delivery device according to claim 7, wherein the radially outer edge is polygonal, namely, trapezium-shaped in the plan view onto the front side of the respective paddle.

10. The delivery device according to claim 1, wherein several or all of the paddles comprise at least one paddle portion which points towards a rotational axis of the impeller in an axial view of the impeller at an inclination to a radial which extends through the respective paddle.

11. The delivery device according to claim 1, comprising the electric drive motor and a power limiter for limiting the electric power which can be supplied to the drive motor to a maximum electric power.

12. The delivery device according to claim 11, wherein the power limiter is a current limiter limiting the electric current to a maximum current.

13. The delivery device according to claim 1, comprising the electric drive motor and a controller or regulator for controlling or regulating the drive motor.

14. The delivery device according to claim 13, wherein the controller or regulator is configured to supply the drive motor with a constant electric voltage and control or regulate the strength of the electric current.

15. The delivery device according to the claim 13, comprising a dosing member which is connected to the blower and can be adjusted by the controller or regulator between a state of minimum throughput and a state of maximum throughput.

16. The delivery device according to claim 15, wherein the state of minimum throughput is a closed state.

17. The delivery device according to claim 15, wherein the dosing member is a dosing valve.

18. The delivery device according to claim 13, wherein the controller or regulator is configured to operate the blower in a lower rotational speed range of at most 5,000 rpm or at most 3,000 rpm when a predetermined threshold requirement of medium to be delivered is undercut, and to set the volume flow of the medium to be delivered by the dosing member.

19. The delivery device according to claim 13, wherein the controller or regulator is configured to operate the blower in an upper rotational speed range of at least 10,000 rpm or at least 15,000 rpm when a predetermined threshold requirement of medium to be delivered is exceeded, and to set the dosing member to a maximum throughput.

20. The delivery device according to claim 1, further comprising a bypass which connects a high-pressure side of the blower to a low-pressure side of the blower by bypassing the interrupter channel, wherein the high-pressure side extends from the delivery channel via the outlet up to a closing or dosing member which succeeds the blower downstream of the blower, and the low-pressure side extends via the inlet up to and into the delivery channel.

21. The delivery device according to claim 20, wherein the closing or dosing member is a dosing valve.

22. The delivery device according to claim 1, wherein the delivery device is used as a purge device for a combustion engine.

23. The delivery device according claim 22, wherein the combustion engine is a drive motor of a motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0171] Example embodiments of the invention are described below on the basis of figures. Features disclosed by the example embodiments, each individually and in any combination of features, advantageously develop the subject-matter of the claims and aspects as well as the embodiments described above. There is shown:

[0172] FIG. 1 a delivery device for purging a filter for volatile fuel components;

[0173] FIG. 2 characteristic curves of conventional side channel blowers and peripheral blowers;

[0174] FIG. 3 characteristic curves of typical radial blowers;

[0175] FIG. 4 a delivery device comprising a side channel blower featuring an electric drive, in a perspective view;

[0176] FIG. 5 the delivery device of FIG. 4, in a plan view onto the side channel blower;

[0177] FIG. 6 the side channel blower of FIGS. 4 and 5, in a longitudinal section through a delivery channel and an interrupter channel;

[0178] FIG. 7 the side channel blower of FIGS. 4 and 5, in the region of the interrupter channel, wherein a uniformly increased sealing gap is formed between the interrupter channel and paddles of an impeller;

[0179] FIG. 8 a comparison of the increased sealing gap and the sealing gap of a conventional side channel blower, in the same longitudinal section as FIG. 7;

[0180] FIG. 9 a side channel blower in a longitudinal section, wherein a bypass is provided which bypasses the interrupter channel;

[0181] FIG. 10 a housing part of the side channel blower of FIG. 9, in a plan view;

[0182] FIG. 11 the housing part of FIG. 10, in the same plan view;

[0183] FIG. 12 a comparison of delivery-pressure-over-delivery-flow characteristic curves;

[0184] FIG. 13 a comparison of current-consumption characteristic curves;

[0185] FIG. 14 a peripheral blower comprising a bypass valve, in a schematic representation;

[0186] FIG. 15 a side channel blower comprising an integrated bypass valve, in a plan view and a partial section;

[0187] FIG. 16 a comparison of delivery-pressure-over-delivery-flow characteristic curves;

[0188] FIG. 17 a comparison of current-consumption characteristic curves;

[0189] FIG. 18 an impeller comprising paddles exhibiting a rounded axially outer edge;

[0190] FIG. 19 a detail of FIG. 18;

[0191] FIG. 20 the impeller of FIG. 18, in a plan view onto the radially outer circumference;

[0192] FIG. 21 a detail of FIG. 20;

[0193] FIG. 22 a plan view onto the radially outer circumference of an impeller comprising paddles which are chamfered on their axially outer edge;

[0194] FIG. 23 a detail of FIG. 22;

[0195] FIG. 24 a part of the impeller comprising the chamfered paddle edges of FIGS. 22 and 23;

[0196] FIG. 25 a paddle comprising a radially outer edge which is convex in a plan view onto a front side of the paddle;

[0197] FIG. 26 an impeller in which the paddles exhibit an inclination in their radially outer region;

[0198] FIG. 27 a delivery-pressure-over-delivery-flow characteristic curve of a delivery device which is limited in terms of its current consumption; and

[0199] FIG. 28 the current-consumption characteristic curve of the delivery device which is limited in this respect.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0200] FIG. 1 shows a delivery device for venting a fuel tank 100 and regenerating a filter 103 for volatile fuel components. The delivery device comprises a side channel blower or peripheral blower B for delivering purge gas into the suction region 107 of a combustion engine 110 which can in particular be the drive motor of a motor vehicle, i.e. an internal combustion engine. The combustion engine is typically a spark-ignition engine. The purge gas contains, in a mixture with ambient air, the volatile fuel components previously stored in the filter 103 and released for the purpose of regenerating, and the volatile fuel components from the tank 100. The blower B can be reversed in terms of its delivery direction, in order also be able to perform a tank leakage test using the same blower B.

[0201] The blower B is connected to the tank 100 via a venting conduit 101 and to the filter 103 via a regenerating conduit 102 which branches off from the venting conduit 101. The filter 103 can in particular be an activated carbon filter. A shut-off safety valve 105 is arranged in the venting conduit 101, downstream of the junction to the filter 103 and upstream of the blower B in relation to the delivery direction towards the combustion engine 110. When an emergency is detected, for example in the event of a vehicular crash, the shut-off safety valve 105 closes the venting conduit 101 and therefore separates the tank 100 and the filter 103 from the blower B and in particular from the suction region 107 of the combustion engine 110.

[0202] The filter 103 is connected to the outer environment via a shut-off valve 104. In purge operations, i.e. when the purge gas is delivered towards the combustion engine 110 and when the combustion engine 110 is switched off, the shut-off valve 104 is open in order to enable pressure equalisation with the atmosphere. The shut-off valve 104 is closed when a leakage test is being performed on the tank 100.

[0203] The venting conduit 101 leads from the blower B into the suction region 107. The venting conduit 101 can in particular emerge into the suction region 107, which is typically a suction pipe, upstream of a throttle member 108, which is typically a throttle valve. An air filter 109 for the fresh air suctioned by the combustion engine 110 can be arranged in the suction region 107, upstream of the convergence point for the purge gas. A supercharger 111 can be arranged between the convergence point for the purge gas and the throttle member 108.

[0204] A dosing valve 106 is arranged in the venting conduit 101, downstream of the blower B and at or upstream of the convergence point into the suction region 107 in the flow direction towards the combustion engine 110. The dosing valve 106 can in particular be formed as an electric dosing valve and preferably as a pulse-width-modulated dosing valve. The dosing valve 106 can be a switching valve, which can be switched between discrete switched states, or a proportional valve.

[0205] The blower B is driven by an electric motor. The delivery device comprises a controller or regulator 113 for controlling or regulating the drive motor of the blower B and dosing valve 106. The controller or regulator 113 can optionally also control the shut-off valve 104 and/or the shut-off safety valve 105. The controller or regulator 113 is configured to control or regulate the electric motor of the blower B in terms of its rotational speed and optionally in terms of its rotational direction. The controller or regulator 113 is also configured to control or regulate the dosing valve 106. It controls or regulates in accordance with the operating state of the combustion engine 110 and/or the loaded state of the filter 103. In advantageous embodiments, the blower B is controlled or regulated at least in terms of its rotational speed in accordance with a control signal which is representative of the respective operating state of the combustion engine 110.

[0206] The controller or regulator 113 can be arranged in or on a housing of the blower B. It can however instead also be arranged separately from the blower B and connected to the electric motor by a wire connection or also, as applicable, wirelessly. If the combustion engine 110 is the internal combustion engine of a motor vehicle, the controller or regulator 113 can be connected to a superordinate engine controller or can be an integrated part of said engine controller.

[0207] The controller or regulator 113 can be configured to keep the rotational speed of the blower B low, for example in the range of 1,000 to 3,000 rpm, when there is no purge requirement or only a low purge requirement in terms of the loaded state of the filter 103 and/or when the combustion engine 110 is currently in an operating state which is unfavourable for supplying purge gas. The controller or regulator 113 can alternatively or preferably additionally be configured to increase the rotational speed of the blower B and operate the blower B in the upper rotational speed range of for example 15,000 to 25,000 rpm or 15,000 to 20,000 rpm when there is a large purge requirement due to a highly loaded state of the filter 103 and/or when the combustion engine 110 is in an operating state which is suitable for supplying purge gas.

[0208] The controller or regulator 113 is advantageously configured to control and/or regulate the supply of purge gas by altering the rotational speed of the blower B, preferably in the upper rotational speed range, when the purge requirement is high and/or in an operating state of the combustion engine 110 which is favourable for supplying purge gas. In order to set the purge gas flow when the purge requirement is low and/or in operating states of the combustion engine 110 which are unfavourable, the controller or regulator 113 can be configured to control or regulate the supply of purge gas up to and including zero delivery by means of the dosing valve 106 while the blower B is operated in the lower rotational speed range, for example in a rotational speed range of 1,000 to 3,000 rpm. The controller or regulator 113 can then be configured to drive the blower B at a constant, low rotational speed of less than 5,000 rpm or less than 3,000 rpm and to control or regulate the supply of purge gas solely by means of the dosing valve 106 when the purge requirement is low and/or in an operating state of the combustion engine 110 which is unfavourable for purging. Additionally or instead, the dosing valve 106 can be fully opened, and the purge gas can be supplied solely by controlling or regulating the rotational speed of the blower B, when the purge requirement is high and/or in an operating state of the combustion engine 110 which is favourable for purging.

[0209] Where the rotational speed of the blower B is mentioned, this is understood to mean the rotational speed of an impeller of the blower B. If the blower B comprises several impellers, the above statements regarding the controlling and/or regulating principle apply to the rotational speed of each of the impellers.

[0210] The delivery device can comprise a sensor 112 which can in particular be arranged in the venting conduit 101 between the blower B and the suction region 107, preferably between the blower B and the dosing valve 106, in order to measure the mass flow or volume flow or pressure or temperature of the purge gas at said point and to supply said measurement value to the controller or regulator 113. The controller or regulator 113 is embodied as a regulator in such embodiments. It can be connected to a superordinate controller, for example an engine controller, or can be part of said superordinate controller. The controller or regulator 113 can receive a guiding variable as a nominal value and the output signal of the sensor 112 as an actual value from the superordinate controller, in accordance with the operating state and/or load state of the combustion engine 110. When developed into a regulator, the controller or regulator 113 can be configured to regulate the blower B and/or the dosing valve 106 in accordance with the nominal value and the actual value. To this end, it performs a nominal/actual comparison, for example by finding the difference between the nominal value and the actual value, and regulates the blower B and/or the valve 106 using an actuating variable for the blower B, formed as a function of the nominal/actual comparison, and/or an actuating variable for the dosing valve 106, formed as a function of the nominal/actual comparison, in accordance with the previously described dividing regime between the blower B and the dosing valve 106.

[0211] The dosing valve 106 can be arranged separately from the blower B, away from the blower B or on a housing of the blower B, for example directly at the outlet, or in the housing of the blower B. The shut-off safety valve 105 can be arranged separately from the blower B, away from the blower B or on the housing of the blower B, for example directly at the inlet, or in the housing of the blower B. The sensor 112 can be arranged separately from the blower B, away from the blower B or on the housing of the blower B, for example directly at the outlet, or in the housing of the blower B.

[0212] As mentioned, the blower B is a side channel blower or peripheral blower. Blowers B of this type are broadly comparable to radial blowers, such as are typically used in purge gas delivery devices, in terms of their effectiveness, but have the crucial advantage that their working rotational speed range is far lower than the working rotational speed range of radial blowers, typically around a third of that of radial blowers. They are accordingly superior to radial blowers in their acoustic characteristics, since their imbalance-induced structure-borne noise is significantly lower than that of radial blowers. Due to their lower rotational speed, the kinetic energies stored in the rotating masses of the blower are smaller than in radial blowers. This results in advantageous dynamic characteristics. The power consumption, typically the current consumption, is lower because smaller masses have to be accelerated and decelerated when the rotational speed is changed. The side channel blower or peripheral blower can therefore be accelerated and decelerated more rapidly. This is crucially advantageous for use in motor vehicle manufacturing. Conversely, the delivery pressure over delivery flow characteristic curve rises significantly as the delivery flow decreases, and the delivery pressure reaches its highest value at zero delivery, i.e. when the blower outlet is closed. Correspondingly, the power consumption of an electric motor for driving the blower also rises, likewise linearly and in a good approximation, towards zero delivery.

[0213] FIGS. 2 and 3 indicate the characteristic curves for the effectiveness , the delivery pressure p and the electric current consumption I over the delivery flow {dot over (V)} for a side channel blower or peripheral blower B (FIG. 2) and for a radial blower (FIG. 3). NP denotes the nominal point and/or nominal working point for both types of blower. Where delivery pressure is mentioned in relation to the delivery characteristic curve, this is the difference in pressure between the inlet and the outlet, i.e. the increase in pressure which the medium to be deliveredin this case, purge gasexperiences due to the blower B.

[0214] FIG. 4 shows the blower B and an electric drive motor 25 for driving the blower B, in a perspective view. FIG. 5 shows the blower B in a plan view onto the end-facing side facing away from the electric motor 25.

[0215] The blower B comprises a housing part 1 and a housing part 2 which together form the housing 1, 2 of the blower B. The housing part 2 serves as a cover for the housing part 1. The blower B comprises an inlet 3 and an outlet 4 for the medium to be delivered by the blower Bin the example embodiment, purge gas. In the housing 1, 2, an impeller 10 which in FIG. 5 can be seen through the inlet 3 is arranged such that it can rotate about a rotational axis R. When the impeller 10 is rotary-driven anti-clockwise, as indicated by a directional arrow, the medium to be delivered flows via the inlet 3 parallel to the rotational axis of the impeller 10, i.e. axially, into a delivery channel which extends in the circumferential direction in the housing 1, 2, while it is expelled via the outlet 4 tangentially with respect to the rotational axis of the impeller 10. Due to the axial inward flow, the blower B of the example embodiment is a side channel blower; if the medium to be delivered flows in radially or tangentially on the radially outer circumference of the impeller 10, it would be a peripheral blower. Within the context of an aspect of the invention, the term blower is intended to encompass side channel blowers and peripheral blowers equally.

[0216] The electric motor 25 is arranged coaxially with the impeller 10. The shaft of the electric motor 25 can in particular directly form the drive shaft for the impeller 10. The housing part 1 can be elongated in the shape of a socket, and its elongated region can surround the electric motor 25. Alternatively, the electric motor 25 can be arranged in a motor housing of its own, and said motor housing can be fitted on the housing 1, 2 of the blower B.

[0217] The electric motor 25 receives its control signals from the controller or regulator 113 (FIG. 1) and is controlled or regulated in terms of its rotational speed and optionally also its rotational direction by the controller or regulator 113.

[0218] FIG. 6 shows the blower B in a longitudinal section. The blower B comprises the housing parts 1 and 2, which together form the housing 1, 2 of the blower B, and the impeller 10 which can rotate in the housing 1, 2 about the rotational axis R. A plurality of paddles 13 are arranged on the radially outer circumference of the impeller 10 in a distribution over the circumference, expediently in a uniform distribution over the circumference, and protrude radially outwards over the radially outer circumference of the impeller 10. The radially outer circumference of the impeller 10 comprises a radially protruding circumferential bulge 11 into which the paddles 13, which otherwise protrude freely from the circumference of the impeller 10, protrude slightly. The circumferential bulge 11 serves to fasten the paddles 13 stably on the impeller 10. The paddles 13 can for example be placed or inserted into the circumferential bulge 11 and additionally connected to the impeller 10 in a material fit.

[0219] A delivery channel 5 and an interrupter channel 8 are formed in the housing 1, 2, one behind the other in the circumferential direction around the rotational axis R, and the paddles periodically pass, one after the other, through the delivery channel 5 and the interrupter channel 8 when the impeller 10 is rotary-driven. The inlet 3 and the outlet 4 (FIG. 4) emerge into the delivery channel 5. The delivery channel 5 extends at least from the inlet 3 up to at least the outlet 4. The interrupter channel 8 serves to fluidically separate the inlet 3 and the outlet 4 and accordingly surrounds the paddle 13 or each of the paddles 13 situated in the interrupter channel 8, forming a sealing gap 24.

[0220] The delivery channel 5 comprises at least one side channel, such as is known from side channel blowers and peripheral blowers. In the example embodiment, the delivery channel 5 comprises a first side channel 6, which extends in the circumferential direction from the inlet 3 up to the outlet 4 along one end-facing side of the paddles 13, and a second side channel 7 which likewise extends from the inlet 3 up to the outlet 4, along the other end-facing side of the paddles 13. In the example embodiment, the two side channels 6 and 7 are also connected via a radial channel which extends from the inlet 3 up to the outlet 4 along the radially outer circumference of the paddles 13.

[0221] When the impeller 10 is rotary-driven, the medium to be delivered which is suctioned via the inlet 3 (FIGS. 4 and 5) is swept along in the delivery cells between adjacent paddles 13. Due to centrifugal force, the medium to be delivered flows in the circumferential direction in the delivery cells, radially outwards, against the facing inner wall of the delivery channel 5, where it is deflected axially outwards and flows through the respective side channel 6 and 7 into a delivery cell which is a trailing delivery cell in relation to the rotational movement, such that overall a spiral flow around the paddles 13 is established and the medium to be delivered is expelled through the outlet 4 at an increased pressure. The delivery effect of the blower B is based on the rotational flow and on impulse transmission on the front sides of the paddles 13, i.e. the sides which are front sides in the rotational direction, which combine to result in the spiral flow.

[0222] The effective area for impulse transmission, i.e. the effective area A.sub.P of the paddle, is marked in FIG. 6 by crosshatching on the paddle 13 situated in the delivery channel 5. The effective area A.sub.P of the paddle is the area of the paddle which points orthogonally with respect to the rotational direction or, if the paddle does not exactly extend radially, the proportion of the area of the paddle which points orthogonally with respect to the rotational direction. In the example embodiment, the effective area A.sub.P of the paddle is the area of the paddle within the outer edge of the paddle, less the longitudinal sectional area of the circumferential bulge 11. If the paddles 13 protrude at an inclination to the radial onto the rotational axis R, i.e. are for example plainly oblique or roundly curved or inverted, then the effective area A.sub.P of the paddle is the area of the paddle projected in or counter to the rotational direction of the impeller 10. In this projection, the points on the front side of the respective paddle 13 are projected on parallel orbits into the same central longitudinal sectional plane. The rotational axis R extends in this central longitudinal sectional plane.

[0223] Radially inwards from the paddles 13, the impeller 10 comprises a constriction 12 on each of its two end-facing sides. The respective constriction 12 completely encircles the rotational axis R. The housing parts 1 and 2 each engage the assigned constriction 12 via a projection 1a and 2a which correspondingly encircles the rotational axis R. This engagement improves the seal on the delivery channel 5 and interrupter channel 8 towards the radially inner side, in that the engagement forms a sinuous sealing gap 10a, i.e. a labyrinth seal, on each of the two end-facing sides of the impeller 10. The engagement can also serve to radially and/or axially guide the impeller 10.

[0224] FIGS. 7 and 8 show a first example embodiment of a blower B for which the delivery-pressure-over-delivery-flow characteristic curve is flattened towards zero delivery. Only the radially outer region of the housing 1, 2 and impeller 10 is shown, comprising a modified, i.e. widened interrupter channel 9 and a correspondingly increased sealing gap 20. Aside from widening the interrupter channel 9 and by association increasing the sealing gap 20, the blower B modified in this way corresponds to the blower B of FIGS. 4 to 6.

[0225] The paddles 13 each comprise a free outer edge which extends from a left-hand base point 14 of the paddle located on the radially outer circumference of the impeller 10, along a first end-facing side, then along a radially outer circumference and then along the other end-facing side of the paddle 13 up to a right-hand base point 15 of the paddle located on said other end-facing side on the radially outer circumference of the impeller 10. This free outer edge of the paddle which extends from the base point 14, which is the left-hand base point of the paddle in FIG. 7, up to the right-hand base point 15 of the paddle limits the effective area A.sub.P of the paddle. The increased sealing gap 20 is limited on the inner side by the outer edge of the paddle and on the outer side by the inner walls of the interrupter channel 9 which face the outer edge of the paddle. Accordingly, the sealing gap 20 comprises a first axial sealing gap 21 which extends along the first end-facing side of the paddle 13, a radial sealing gap 22 which extends along the radially outer circumference of the paddle 13, and a second axial sealing gap 23 which extends along the other end-facing side of the paddle 13. The first axial sealing gap 21, the radial sealing gap 22 and the second axial sealing gap 23 together form the increased sealing gap 20, i.e. they each form sealing gap portions of the overall sealing gap 20.

[0226] The increased sealing gap 20 extends radially up to the level of each of the base points 14 and 15 of the paddle and exhibits the area A.sub.SG in the longitudinal sectional plane of the effective area A.sub.P of the paddle. If the directly adjoining interrupter channel 9 is also then widened radially inwards from the paddles 13 in an overlap with the impeller 10, this wider region does not count towards the sealing gap 20. For the purposes of comparison, only the sealing gap which extends around the paddles 13 from the base point 14 to the base point 15 is adduced as the increased sealing gap 20. Similarly, for the purposes of comparison, only the cross-section of the channel in the longitudinal sectional plane of the effective area A.sub.P of the paddle which the paddles 13 pass through is understood to be the free cross-section A.sub.IC of the interrupter channel 9.

[0227] FIG. 8 shows the widened interrupter channel 9 and accordingly increased sealing gap 20 and, in a dashed line for comparison, an interrupter channel 8 and sealing gap 24 such as may be encountered in conventional side channel blowers and peripheral blowers. The conventional sealing gap 24 is dimensioned such that the downstream end portion of the delivery channel 5 (FIG. 6), into which the outlet 4 (FIG. 4) emerges, is fluidically separated as far as possible from the upstream end portion of the delivery channel 5 into which the inlet 3 emerges. Conversely, the conventional sealing gap 24 is precisely of a size such that the free movement of the impeller 10 is ensured in conditions such as are to be expected during operations.

[0228] In the example embodiment, the increased sealing gap 20 is widened along the entire outer edge of the paddle, i.e. continuously from the base point 14 up to the base point 15, axially on the two end-facing sides and radially on the radially outer circumference, as compared to the conventional sealing gap 24. The axial sealing gaps 21 and 23 each exhibit an axial gap width W.sub.a measured in the axial direction. The radial sealing gap 22 exhibits a radial gap width W.sub.r measured in the radial direction. The two axial sealing gaps 21 and 23 can be equal, but can in principle also be unequal. In the example embodiment shown, the radial gap width W.sub.r is larger than the axial gap width W.sub.a. Alternatively, however, the gap widths W.sub.a and W.sub.r can also be equal, or the axial gap width W.sub.a of the axial sealing gap 21 and/or the axial gap width W.sub.a of the other axial sealing gap 23 can be larger than the radial gap width W.sub.r.

[0229] The axial gap width W.sub.a of the first sealing gap 21 and/or the axial gap width W.sub.a of the second sealing gap 23 can (each) be invariable, i.e. constant, over the entire radial length of the respective sealing gap 21 and 23. Instead or expediently in addition, the radial gap width W.sub.r can be constant over the entire axial length of the radial sealing gap 22. Although constant gap widths W.sub.a and W.sub.r are preferred, not least because they are simple to produce, one or both of the axial gap widths W.sub.a can vary over the radial length of the respective sealing gap 21 and 23. Instead or additionally, the radial gap width W.sub.r can vary. If one or more of the gap widths W.sub.a and W.sub.r varies/vary along the respective sealing gap 21 to 23, the respective axial gap width W.sub.a increases only monotonically in the radial direction and preferably over at least the majority of the radial length, in order to obtain a sealing gap 21 and/or 23 which is uniformly broadened as viewed over its length, despite said variation, and in particular to avoid local constrictions. If the radial gap width W.sub.r varies in the axial direction, this variation occurs uniformly over the entire axial length of the sealing gap 22, wherein the sealing gap 22 can simply extend convexly in a uniform arc, i.e. can bulge outwards, or can simply extend concavely in a uniform arc, i.e. can bulge inwards.

[0230] In expedient embodiments, such as the example embodiment, a widened interrupter channel 9 is provided in order to realise the increased sealing gap 20. At their axially outer base points 14 and 15, the paddles 13 each exhibit the axial width of the annular region of the impeller 10 which borders the paddles 13 radially inwards. The opposing inner walls of the interrupter channel 9 which face each other axially across the respective paddle 13 recede axially via a collar formed at the level of each of the base points 14 and 15 of the paddle, in order to obtain the respective axial gap width W.sub.a. In alternative embodiments, the paddles 13 can be embodied to be narrower along one end-facing side and/or the other end-facing side, such that the inner wall of the interrupter channel 9 which faces the axially recessed axial edge of the paddle can smoothly proceed radially outwards past the respective base point 14 or 15 of the paddle. Providing the uniformly increased sealing gap 20 by axially widening the interrupter channel 9 is however preferred.

[0231] The axial sealing gap 21 and/or the axial sealing gap 23 exhibits or each exhibit an axial gap width W.sub.a throughout the respective sealing gap 21 and 23 which is larger than, and in advantageous embodiments at least twice as large as, the axial gap width of the axial sealing gap 10a, adjoining on the radially inner side, between the impeller 10 and the axially facing inner wall region of the interrupter channel 9. The radial gap width W.sub.r can be larger, throughout its axial length, than the axial gap width of the radial sealing gap 10a and preferably at least twice as large as the axial gap width of the sealing gap 10a. The sealing gap 10a expediently exhibits the same gap width throughout its entire profile. The gap width is also preferably invariable in the region of the engagement between the constriction 12 and the projections 1a and 2a, aside from any deviations in the corner regions and edge regions.

[0232] The leakage which is specifically set via the interrupter channel 9 by means of increasing the sealing gap 20 can in particular be characterised by the ratio A.sub.SG/A.sub.P between the area of the sealing gap and the effective area of the paddle. In advantageous embodiments, it holds that A.sub.SG/A.sub.P0.06 or A.sub.SG/A.sub.P0.07. In relation to favourable degrees of effectiveness in the full-load range, i.e. at delivery flows equal to or greater than the delivery flow at the nominal delivery point or nominal point, it is advantageous if A.sub.SG/A.sub.P0.25 or A.sub.SG/A.sub.P0.20. Alternatively or additionally, it holds for the ratio between the area A.sub.SG of the sealing gap and the cross-section A.sub.IC of the channel that A.sub.SG/A.sub.IC0.05 or preferably A.sub.SG/A.sub.IC0.06. With regard to the degree of effectiveness, it is favourable if A.sub.SG/A.sub.IC0.20 or A.sub.SG/A.sub.IC0.15 or A.sub.SG/A.sub.IC0.13.

[0233] FIG. 9 shows a blower B of a second example embodiment, in a longitudinal section in which the rotational axis R extends. The electric motor 25, which is arranged in a motor housing 26, is also shown. The electric motor 25 comprises a rotor 27 and a stator 28 which are shown in FIG. 9 as a single block. The electric motor 25 can for example be embodied as a brushless DC or asynchronous motor, expediently comprising an integrated rotational angle transmitter. The motor housing 26 is fitted on the housing part 1 of the blower housing 1, 2. The impeller 10 is placed directly on the motor shaft and non-rotationally connected to the motor shaft. A shaft seal 29 seals off the region connecting the impeller 10 and the motor shaft.

[0234] In order to flatten the delivery-pressure-over-delivery-flow characteristic curve, a bypass is provided in the second example embodiment, through which the medium to be delivered can flow back from a region of high pressure into a region of low pressure by bypassing the interrupter channel, for example a conventional interrupter channel 8 (FIG. 6) or a widened interrupter channel 9 (FIGS. 7 and 8).

[0235] The bypass can be provided solely within the housing 1, 2 of the blower B or can extend successively through the blower housing 1, 2 and the motor housing 26, as indicated in FIG. 9 by directional arrows. FIG. 9 also indicates how the bypass can bifurcate, such that a first bypass branch extends in the blower housing 1, 2, and a bypass branch which branches off from the first bypass branch extends through the motor housing 26. A bypass branch which is realised in the blower housing 1, 2 can in particular extend on the end-facing side of the impeller 10 which faces the electric motor 25. This first variant is realised in the second example embodiment. In an alternative second variant, a comparable bypass can extend on the end-facing side of the impeller 10 which faces away from the electric motor 25. In a third variant, one bypass can extend as in the second example embodiment and another bypass can extend on the end-facing side of the impeller 10 which faces away from the electric motor 25, each within the housing 1, 2. In all three variants, an additional bypass or bypass branch can optionally lead through the motor housing 26.

[0236] FIG. 10 shows the housing part 1 in an axial plan view onto the inner side of the housing part 1. The bypass as a whole is referred to as the bypass 30. The bypass branch which extends in the blower housing 1, 2 on the end-facing side of the impeller 10 which faces the electric motor 25 comprises bypass portions 32, 33 and 34 which extend in the housing part 1, axially facing the impeller 10.

[0237] The bypass 30 comprises the upstream bypass portion 32 which branches off from the delivery channel 5 at a divergence opening 31 which emerges in the high-pressure region of the delivery channel 5. Of the delivery channel 5, the side channel 6 formed in the housing part 1 can be seen in the plan view of FIG. 10. The divergence opening 31 is arranged in an end region of the delivery channel 5in this case, the side channel 6near the outlet 4. The bypass 30 also comprises the central bypass portion 33 into which the bypass portion 32 emerges at its downstream end. The downstream bypass portion 34 adjoins the central bypass portion 33 in the flow direction from the high-pressure region to the low-pressure region and emerges at its downstream end into the low-pressure region of the delivery channel 5in this case, the side channel 6via a convergence opening 35. Advantageously, the bypass portion 34 emerges into an end portion of the delivery channel 5 and/or side channel 6 which comprises the inlet 3.

[0238] The bypass portions 32 and 34 are cost-effectively, in terms of production, embodied as continuously straight channel portions which are axially open towards the impeller 10. The bypass portions 32 and 34 lead through the projection 1a which, aside from the bypass portions 32 and 34, serves to improve the seal on the delivery channel 5 towards the radially inner side along the profile of the projection 1 a.

[0239] As already mentioned, a second bypass branch which leads through the motor housing 26 is provided in the second example embodiment. The second bypass branch comprises an upstream bypass portion 36 and a downstream bypass portion 38 which each emerge in the central bypass portion 33, whence they lead through the housing part 1 and establish a connection to the interior space of the motor housing 26. The points at which the bypass passages 36 and 38 emerge can be seen in FIG. 10. In the motor housing 26, the bypass 30 which is extended in this way can surround the electric motor 25 over a large area in a bypass portion 37, as shown by way of example in FIG. 9, such that the medium to be delivered can cool the electric motor 25, i.e. the rotor 27 and/or the stator 28 of the electric motor 25, over a correspondingly large area as it flows through the bypass branch 36, 37 and 38.

[0240] FIG. 11 shows the inner side of the housing part 1 in the same plan view as FIG. 10. Angular extents , and are indicated, which serve to characterise an advantageous arrangement of the divergence opening 31 and convergence opening 35. Proceeding from the interrupter channel 8 and progressing in the rotational direction (anti-clockwise) in the delivery channel 5, the angular extents , and mark an upstream delivery portion 5a in which the convergence opening 35 emerges, an intermediate delivery portion 5b, and a downstream delivery portion 5c which extends up to the interrupter channel 8 and in which the divergence opening 31 branches off. The intermediate delivery portion 5b thus extends in the rotational direction up to a point in front of the divergence opening 31 and counter to the rotational direction up to a point in front of the convergence opening 35, i.e. at most up to the divergence opening 31 in the rotational direction and at most up to the convergence opening 35 counter to the rotational direction, and has the angular extent . The upstream delivery portion 5a borders the interrupter channel 8 and extends in the rotational direction and delivery direction from the interrupter channel 8 up to the intermediate delivery portion 5b and at least completely over the convergence opening 35. The delivery portion 5a has the angular extent . The downstream delivery portion 5c extends counter to the rotational direction and delivery direction from the interrupter channel 8 up to the intermediate delivery portion 5b and at least completely over the divergence opening 31 and has the angular extent .

[0241] The bypass 30 (FIGS. 9 and 10) can comprise one or more other bypass portions, each comprising another divergence opening and/or another convergence opening. If two or more divergence openings branch off from the delivery channel 5 in the high-pressure region of the delivery channel 5, then the downstream delivery portion 5c extends over all of these divergence openings. If the extended bypass comprises the convergence opening 35 and one or more other convergence openings which emerge in the low-pressure region of the delivery channel 5, then the upstream delivery portion 5a extends over all of these convergence openings.

[0242] In advantageous embodiments, the upstream delivery portion 5a has an angular extent of at most 60 or at most 45. The angular extent of the downstream delivery portion 5c preferably measures at most 120 or at most 90 or at most 70. The intermediate delivery portion 5b, in which neither a divergence opening nor a convergence opening for bypassing the interrupter channel 8 emerges, extends over an angle of advantageously at least 45 or at least 90. In preferred embodiments, the angular extent measures at least 120 or at least 180. The angular extents , and can in particular be chosen such that <45, >180 and <70. While this is a preferred combination for the angular extents , and , the relationships previously mentioned can however in principle also be realised in any other combination as desired. With regard to a good degree of effectiveness, however, it is advantageous if it at least holds that >180.

[0243] In advantageous embodiments, the sum ++ of the angular extents, which corresponds to the angular extent of the delivery channel 5 as a whole, is greater than 270 and preferably greater than 300.

[0244] It is favourable for establishing the spiral flow if the medium to be delivered which is guided back through the bypass 30 is not introduced in the form of a concentrated tangential jet but rather radially or at an angle of at least 45 to the tangential direction. In the second example embodiment, the medium to be delivered which is guided back is channelled back into the delivery channel 5 radially or almost radially through the convergence opening 35, as can be seen in FIGS. 10 and 11.

[0245] FIGS. 12 and 13 schematically show the delivery-pressure-over-delivery-flow characteristic curve p over {dot over (V)} and the characteristic curve for the current consumption I over {dot over (V)}. The corresponding characteristic curve of conventional side channel blowers and peripheral blowers is indicated in each of the two diagrams as a dashed line for comparison. The characteristic curves for a blower B in accordance with an aspect of the invention are shown in a continuous line, wherein the characteristic curves apply both to setting a specific leakage by increasing the sealing gap (first example embodiment) and to setting a specific leakage by providing a bypass (second example embodiment). As can be seen in FIG. 12, the delivery pressure and/or increase in delivery pressure p drops in the full-load range from the nominal point NP in the direction of increasing delivery flow {dot over (V)} at a lower pitch than in conventional comparative blowers and has a significantly flattened profile over the overload range, starting at the nominal point NP and in the direction of minimum delivery flow. A certain loss of delivery pressure at the nominal point NP is negligible. The relationships are similar in the characteristic curve for the current consumption I.

[0246] The two measures for specifically setting a leakage, i.e. by means of an increased sealing gap on the one hand and by means of a bypass on the other, can be realised separately from each other or also in combination. When realised in combination, the sealing gap can be broadened to a lesser extent and/or the bypass can be realised with a larger overall flow resistance and/or the angular distance between the divergence opening and the convergence opening can be reduced, such that the two measures in combination generate the desired flattening of the delivery-pressure-over-delivery-flow characteristic curve. In simple and not least for this reason preferred embodiments, however, only one of the two measures is realised.

[0247] FIG. 14 schematically shows a blower B of a third example embodiment. The blower B comprises an inlet 3 which emerges on the radially outer circumference of the delivery channel 5. The blower B is therefore a peripheral blower. In the third example embodiment, the delivery pressure over delivery flow characteristic curve is flattened by means of a bypass 40a which, like the bypass 30 of the second example embodiment above, bypasses the interrupter channel 8 (FIG. 6) or the widened interrupter channel 9 of the first example embodiment (FIGS. 7 and 8). Unlike the second example embodiment, a bypass valve 43 is arranged in the bypass 40a.

[0248] The bypass 40a comprises an upstream bypass portion 42, a downstream bypass portion 44 and the bypass valve 43 which connects the bypass portions 42 and 44 to each other when the bypass valve 43 assumes an opened valve state. In expedient embodiments, the bypass valve 43 can assume a closed state in which it separates the bypass portions 42 and 44 from each other and thus blocks the bypass 40a. The bypass valve 43 can in principle be adjusted between a state of minimum throughput and a state of maximum throughput continuously or discontinuously in one or more increments, preferably in this case abruptly between minimum and maximum throughput. The state of minimum throughput can in particular be a closed state, but can in principle also be a state in which the bypass valve 43 permits a small throughput, i.e. a small leakage flow.

[0249] The bypass 40a can connect the outlet 4 to the inlet 3, in that the divergence opening 41 emerges in the outlet 4, the bypass 40a accordingly branches off from the outlet 4, and the convergence opening 45 emerges in the inlet 3. In the example embodiment, the divergence opening 41 emerges in an outlet support which protrudes from the housing of the blower B, i.e. the bypass 40a branches off in the region of the outlet support, and the convergence opening 45 emerges in a convergence support which protrudes from the housing of the blower B. The convergence support and the outlet support form part of the housing of the blower B. The bypass 40a is advantageously formed while still within or on the housing of the blower B, such that the bypass 40a does not have to be fitted at the point of installation in addition to the blower B, but can rather be fitted together with the blower B as a unit.

[0250] The bypass valve 43 comprises a valve element 46, for example a valve piston, and a valve spring 47 which acts on the valve element 46 towards the position of minimum throughput. A control conduit 48 branches off on the high-pressure side of the blower B, via which medium to be delivered is guided from the high-pressure side of the blower B to the valve element 46, in order to apply a pressure of the high-pressure side of the blower B to the valve element 46, counter to the spring force of the valve spring 47. The control conduit 48 can for example branch off in the high-pressure region of the delivery channel 5 or in a portion of the outlet 4 which directly adjoins the delivery channel 5. The control conduit 48 can instead also branch off from the outlet support at the outlet 4 or, as in the example embodiment, branch off from the upstream bypass portion 42. The high-pressure side of the blower B extends via the outlet 4 from a downstream portion of the delivery channel 5 up to a consumer to which the medium to be delivered is supplied by means of the blower, for example up to the suction region 107 of the arrangement in FIG. 1, or up to a closing and/or dosing member, for example the dosing valve 106 (FIG. 1), which optionally succeeds the blower B downstream. The low-pressure side of the blower B comprises an upstream delivery portion of the delivery channel 5 and extends upstream from the latter via the inlet 3. The differential pressure between the pressure of the medium to be delivered which is on the high-pressure side and that on the low-pressure side of the blower B thus acts on the valve element 46 in all the variants.

[0251] FIG. 15 shows a blower B exhibiting a specific leakage according to a fourth example embodiment. The housing part 1 of the blower B is shown in an axial view onto the inner end-facing side of the housing part 1. The side channel 6 of the delivery channel 5 which is thus exposed can be seen.

[0252] Similar to the third example embodiment, the specific leakage is established in the fourth example embodiment by a bypass 40b which is exposed in a partial section of the housing part 1. Unlike the bypass 40a of the third example embodiment, the bypass 40b branches off from the outlet 4 at a divergence opening 41 in a portion of the outlet 4 which extends between the delivery channel 5 and an outlet support which protrudes from the housing part 1. In the example embodiment, the divergence opening 41 radially lies directly above the interrupter channel 8.

[0253] The bypass 40b emerges at a convergence opening 45 in an upstream delivery portion of the delivery channel 5 which borders the interrupter channel 8. The statements made with respect to the convergence opening 35 of the second example embodiment (FIGS. 9 to 11) advantageously apply in relation to the arrangement of the convergence opening 45. The divergence opening 41 could also in principle even emerge in a downstream delivery portion of the delivery channel 5, wherein the statements made with respect to the downstream delivery portion 5c of the second example embodiment apply with regard to the downstream delivery portion in such a modification.

[0254] The bypass 40b extends from the divergence opening 41 up to the convergence opening 45, radially above the interrupter channel 8 or axially alongside the interrupter channel 8, and can in particular extend at a narrow radial distance along the outer circumference of the interrupter channel 8, as in the example embodiment. The bypass 40b can be closed by the other housing part 2 (FIG. 3) or can advantageously be arranged completely within the housing part 1, as in the example embodiment. The housing of the blower B or just the housing part 1 can be radially widened locally, forming the bypass 40b in the circumferential region from the divergence opening 41 up to the convergence opening 45.

[0255] Like the bypass 40a of the third example embodiment, the bypass 40b comprises an upstream bypass portion 42, which branches off from the outlet 4 at its divergence opening 41, and a downstream bypass portion which emerges at its convergence opening 45 in the delivery channel 5. A bypass valve 43 is arranged between the divergence opening 41 and the convergence opening 45.

[0256] The bypass valve 43 comprises a valve element 46 which can be moved back and forth between a position of minimum throughput and a position of maximum throughput. In the position of minimum throughput, the bypass valve 43 can permit a certain small leakage flow or advantageously separate the divergence opening 41 from the convergence opening 45 and thus interrupt the bypass 40b. The bypass valve 43 also comprises a valve spring 47 which applies a spring force to the valve element 46 towards the position of minimum throughput. A differential pressure which prevails between the divergence opening 41 and the convergence opening 45 acts counter to the valve spring 47.

[0257] The bypass valve 43 of the fourth example embodiment comprises a spring space 49 in which the valve spring 47 is arranged. The spring space 49 is connected to the convergence opening 45 via the downstream bypass portion and is thus relieved of pressure.

[0258] The bypass valve 43 is embodied as a reflux valve in the fourth example embodiment, but can in principle also be formed as a valve comprising for example a valve slider. The valve spring 47 pushes the valve element 46 into a valve seating 46a. Each of the spring force and the opposing pressure force of the medium to be delivered points through the valve seating 46a. If the valve element 46 moves towards the position of maximum throughput, a leakage flow of the medium to be delivered flows into the bypass portion 42 via the divergence opening 41, through the valve seating 46a and past the valve element 46, into the downstream bypass portion and finally through the latter's convergence opening 45 into the delivery channel 5.

[0259] FIGS. 16 and 17 schematically show the delivery-pressure-over-delivery-flow characteristic curve of a blower B comprising a bypass valve 43 (third example embodiment and fourth example embodiment) and the characteristic curve for the current consumption I, each in a comparison with the corresponding characteristic curve of a conventional side channel blower or peripheral blower. The characteristic curve of the blower B in accordance with an aspect of the invention is shown in a continuous line, and the characteristic curve of the conventional blower is shown in a dashed line, in each case. It can be seen that the delivery pressure over delivery flow characteristic curve and accordingly also the current consumption over delivery flow characteristic curve of the blower B in accordance with an aspect of the invention can correspond, in the full-load range, to the characteristic curve of a comparative blower which is identical aside from the bypass valve 43, namely if the bypass valve 43 interrupts the bypass 40a or 40b in its state of minimum throughput, i.e. if the state of minimum throughput is a closed state.

[0260] In the third example embodiment and fourth example embodiment, the leakage flow can be set very exactly by means of the bypass valve 43. The respective bypass valve 43 is configured such that the valve element 46 moves from the position of minimum throughput towards the position of maximum throughput only and always when a differential pressure between the pressure at the divergence opening 41 and the pressure at the convergence opening 45, which is predetermined by means of the valve spring 47, is exceeded. The respective bypass valve 43 can in particular be configured such that this threshold pressure corresponds to at least 80% or at least 90% of the nominal delivery pressure of the blower B. The nominal delivery pressure is the delivery pressure at the nominal delivery point NP of the blower B. If the configuration is such that the threshold pressure is greater than the nominal delivery pressure of the blower B, then the threshold pressure measures at most 120% or at most 110% of the nominal delivery pressure in advantageous embodiments. Configuring the bypass valve 43 such that the threshold pressure corresponds to the nominal delivery pressure of the blower B is particularly expedient.

[0261] FIG. 18 shows an impeller 10 comprising paddles 13 which comprise a rounded profile 16 on both axially outer edges of the respective paddle 13. FIG. 19 shows a detail of FIG. 18 in an enlarged representation. FIG. 20 is a plan view onto the radially outer circumference of the impeller 10 and the radially outer edge of the paddles 13. FIG. 21 is an axially outer region of the paddle in the same plan view as in FIG. 20 in an enlarged representation, such that the rounded profile 16 can more clearly be seen. The rounded profile 16 points in the rotational direction indicated by a directional arrow, i.e. the front sides of each of the paddles 13 are rounded on both axially outer edges of the paddle. In modifications, the paddles 13 can also comprise the rounded profile 16 along only one of their axially outer edges. The front sides of each of the paddles 13 can optionally be rounded on the radially outer edge of the paddle. A rounded profile 16 on the radially outer edge of the paddle can be provided instead of or in addition to the rounded profile 16 on one or both of the axially outer edges of the paddle.

[0262] FIGS. 22 to 24 show an impeller 10 comprising paddles 13 which comprise a chamfer 17, i.e. an oblique profile, instead of the rounded profile 16 (FIGS. 18 to 21) on the front sides of both their axially outer edges. In one modification, the paddles 13 can also be chamfered on the front sides of only one of their two axially outer edges. In another modification, a chamfer 17 can be provided additionally or only on the front side of the radially outer edge of the respective paddle 13. The chamfer 17 can point at an angle of 10 to 80 to an axial which is parallel to the rotational axis R.

[0263] The paddles can thus comprise the rounded profile 16 over their entire outer edge or only in one or more portions of their edge or can instead comprise the chamfer 17 over their entire outer edge or only in one or more portions of their edge. In modifications, the paddles 13 can comprise the rounded profile 16 in one or more portions of their edge and the chamfer 17 in one or more other portions of their edge, as viewed over their entire outer edge.

[0264] The paddles 13 can comprise a rounded profile 16 and/or a chamfer 17 on their front sides only. Alternatively, the paddles 13 can also be convexly rounded or chamfered on their outer edge. A convex chamfer 17 can in particular be trapezium-shaped or conically tapered as viewed in the radial plan view of FIGS. 20 and 22.

[0265] Due to the rounded profile 16 and the chamfer 17 of the outer edge of the paddle, the area of the sealing gap of the paddles 13 which is provided in the circumferential direction in the interrupter channel is reduced. This measure also reduces the energy transmission in the overload range, i.e. when there is significant throttling on the pressure side, and thus flattens the delivery-pressure-over-delivery-flow characteristic curve.

[0266] FIG. 25 shows a paddle 13 comprising a radially outer edge 18 which is convex in a plan view onto the front side of the paddle 13. The convex edge 18 of the paddle can be conical or trapezium-shaped or alternatively can also roundly bulge radially outwards.

[0267] This measure also establishes a specific leakage in the interrupter channel via the circumferential extent of the interrupter channel.

[0268] FIG. 26 shows an impeller 10 comprising paddles 13 which exhibit an inclination to a radial which extends through the rotational axis R and the respective base point of the paddle. In the example embodiment, the paddles 13 each comprise a radially inner region and a radially outer region 19 which inverts away from the inner region. The inner region of each of the paddles points radially with respect to the rotational axis R of the impeller 10, while the radially outer region 19 of the paddle inverts away from the radially inner region of the paddle in the forward direction. The inner region of the paddle and the outer region 19 of the paddle are each straight in the axial view.

[0269] In modifications, the paddles 13 can also be inclined in the forward direction, i.e. in the rotational direction, over their entire radial extent. In another modification, they can invert more than once as viewed over their radial height or can be roundly inclined continuously or only in a radially outer region of the paddle. Alternatively, the paddles 13 can be inclined counter to the rotational direction over their entire radial extent or only in portions. It is however preferred that they be inclined in the forward direction. If, as is preferred, the rotational direction of the blower can be reversed, then the rotational direction is understood to be the rotational direction in which the impeller is predominantly driven and/or for which the blower is primarily configured.

[0270] In the example embodiments described above, the delivery pressure over delivery flow characteristic curve is flattened by geometrically altering the blower and/or by means of a bypass valve. Alternatively or additionally, it can also be flattened by limiting the power consumption, in particular the current consumption, of the electric motor 25 (FIG. 3).

[0271] FIGS. 27 and 28 respectively show, in a continuous line, the delivery pressure over delivery flow characteristic curve and the current consumption over delivery flow characteristic curve of a delivery device (blower B and motor) comprising an electric motor 25 which is limited in terms of its current consumption, in a comparison with a conventional side channel blower or peripheral blower which is identical aside from the limiting. The characteristic curves of the comparative blower are shown in a dashed line. The delivery pressure over delivery flow characteristic curve can in practice be set as desired by means of limiting the power consumption, advantageously the current consumption I. FIG. 27 shows an example of an instable profile, i.e. the delivery pressure over delivery flow characteristic curve drops in the overload range from the nominal delivery pressure at the nominal point NP towards zero delivery. The profile of the current consumption I, as a guiding variable, is shown in FIG. 28.

[0272] The measures in accordance with an aspect of the invention can each be realised individually in a blower B. It is however also possible to employ two or more of the measures, which have been individually disclosed merely by way of example, in combination in the same blower, in order to obtain the flattened and preferably inverting delivery-pressure-over-delivery-flow characteristic curve. Within the meaning of an aspect of the invention, the description of a flattened characteristic curve also encompasses a falling, i.e. instable characteristic curve. The one or more measures in combination can be advantageously embodied such that the delivery pressure, i.e. the differential pressure between the inlet 3 and the outlet 4, for example the differential pressure directly across the interrupter channel 8 or 9, is at most 20% or at most 10% above the nominal delivery pressure.

REFERENCE SIGNS

[0273] 1 housing part [0274] 1 a projection [0275] 2 housing part, cover [0276] 2a projection [0277] 3 inlet [0278] 4 outlet [0279] 5 delivery channel [0280] 5a delivery portion [0281] 5b intermediate delivery portion [0282] 5c delivery portion [0283] 6 side channel [0284] 7 side channel [0285] 8 interrupter channel, conventional [0286] 9 widened interrupter channel [0287] 10 impeller [0288] 10a sealing gap [0289] 11 circumferential bulge [0290] 12 constriction [0291] 13 paddle [0292] 14 base point of the paddle [0293] 15 base point of the paddle [0294] 16 axial edge of the paddle, rounded [0295] 17 axial edge of the paddle, chamfered [0296] 18 radial edge of the paddle [0297] 19 inclination of the paddle [0298] 20 increased sealing gap [0299] 21 axial sealing gap [0300] 22 radial sealing gap [0301] 23 axial sealing gap [0302] 24 sealing gap, conventional [0303] 25 electric motor [0304] 26 motor housing [0305] 27 rotor [0306] 28 stator [0307] 29 shaft seal [0308] 30 bypass [0309] 31 divergence opening [0310] 32 bypass portion [0311] 33 bypass portion [0312] 34 bypass portion [0313] 35 convergence opening [0314] 36 bypass portion [0315] 37 bypass portion [0316] 38 bypass portion [0317] 39 - [0318] 40a bypass [0319] 40b bypass [0320] 41 divergence opening [0321] 42 bypass portion [0322] 43 bypass valve [0323] 44 bypass portion [0324] 45 convergence opening [0325] 46 valve element [0326] 46a valve seating [0327] 47 valve spring [0328] 48 control conduit [0329] 49 spring space [0330] 50 - [0331] . . . - [0332] 100 tank [0333] 101 venting conduit [0334] 102 regenerating conduit [0335] 103 filter [0336] 104 shut-off valve [0337] 105 shut-off safety valve [0338] 106 dosing valve [0339] 107 suction region [0340] 108 throttle member [0341] 109 air filter [0342] 110 combustion engine [0343] 111 supercharger [0344] 112 sensor [0345] 113 controller or regulator [0346] A.sub.IC cross-sectional area of the interrupter channel [0347] A.sub.P effective area of the paddle [0348] A.sub.SG area of the sealing gap [0349] B blower [0350] R rotational axis [0351] W.sub.a axial gap width [0352] W.sub.r radial gap width [0353] angular extent [0354] angular extent [0355] angular extent [0356] inclination of the paddle