INTERNAL GEAR FLUID MACHINE

Abstract

An internal gear fluid machine has a first gearwheel having external toothing mounted rotatably about a first axis of rotation and a second gearwheel having internal toothing meshing in regions with the external toothing in an engagement region and mounted rotatably about a second axis of rotation different from the first axis of rotation. A filler piece is arranged between the first gearwheel and the second gearwheel away from the meshing region which bears on the one side against the external toothing and on the other side against the internal toothing, in order to divide a fluid space present between the first gearwheel and the second gearwheel into a first fluid chamber and a second fluid chamber, and housing walls of a machine housing of the internal gear fluid machine being arranged in the axial direction with respect to the first axis of rotation on both sides of the first gearwheel and of the second gearwheel. The second gearwheel is surrounded in the circumferential direction to form a hydrostatic bearing by a bearing recess formed in the machine housing, which bearing recess at least partially overlaps the second gearwheel in the axial direction and is fluidically connected to a fluid connection of the internal gear fluid machine via a fluid line having a flow resistance.

Claims

1. An internal gear fluid machine comprising: a first gearwheel having external toothing and mounted rotatably about a first axis of rotation and a second gearwheel having internal toothing meshing in regions with the external toothing in an engagement region and mounted rotatably about a second axis of rotation different from the first axis of rotation; and a filler piece arranged between the first gearwheel and the second gearwheel away from the engagement region, which filler piece bears on a first side against the external toothing and bears on a second side against the internal toothing, in order to divide a fluid space present between the first gearwheel and the second gearwheel into a first fluid chamber and a second fluid chamber, wherein housing walls of a machine housing of the internal gear fluid machine are arranged in an axial direction with respect to the first axis of rotation on both sides of the first gearwheel and the second gearwheel, and wherein, in order to form a hydrostatic bearing, the second gearwheel is surrounded in a circumferential direction at least in regions by at least one bearing recess which is formed in the machine housing, which bearing recess engages at least partially over the second gearwheel in the axial direction and is fluidically connected to a fluid connection of the internal gear fluid machine via a fluid line having a flow resistance.

2. The internal gear fluid machine according to claim 1, wherein the fluid line extends radially outwards from the at least one bearing recess and/or is straight throughout.

3. The internal gear fluid machine according to claim 1, wherein the fluid line opens radially inwards into the at least one bearing recess by passing through a bottom of the at least one bearing recess to form a muzzle opening.

4. The internal gear fluid machine according to claim 1, wherein the fluid line opens on its side facing away from the at least one bearing recess into a dimensionally larger connection channel, via which it is fluidically connected to the fluid connection.

5. The internal gear fluid machine according to claim 1, wherein a cross-sectional constriction is formed only locally in the fluid line, so that a flow cross-section of the fluid line on both sides of the cross-sectional constriction is larger than a flow cross-section in a region of the cross-sectional constriction.

6. The internal gear fluid machine according to claim 1, wherein the at least one bearing recess is fluidically connected on a side facing away from the fluid line via a leakage gap to a return recess of the internal gear fluid machine, which recess is in flow connection with a suction side of the internal gear fluid machine directly and/or with a fluid tank.

7. The internal gear fluid machine according to claim 1, wherein an interface channel is formed in each of the two housing walls and a common one of the first and second fluid chambers is in fluid connection with the fluid connection of the internal gear fluid machine via both interface channels.

8. The internal gear fluid machine according to claim 1, wherein the fluid connection is a first fluid connection of a plurality of fluid connections and the first fluid chamber is in flow order with the fluid connection present as the first fluid connection via the interface channels present as first interface channels, and in that a second interface channel is formed in each of the housing walls and the second fluid chamber is in fluid connection with a second fluid connection of the internal gear fluid machine via the second interface channels.

9. The internal gear fluid machine according to claim 8, wherein the fluid line opens on its side facing away from the at least one bearing recess into a dimensionally larger connection channel, via which it is fluidically connected to the fluid connection, and wherein one of the interface channels is connected directly and another of the interface channels is connected fluidically to the fluid connection via the connection channel which overlaps the first gearwheel and the second gearwheel in the axial direction.

10. The internal gear fluid machine according to claim 8, wherein the at least one bearing recess is a first bearing recess of a plurality of bearing recesses and the flow resistance is a first flow resistance of a plurality of flow resistances and a second of the bearing recesses is formed in the machine housing spaced in the circumferential direction from the first bearing recess, which at least partially overlaps the second gearwheel in the axial direction, the first bearing recess being fluidically connected to the first fluid connection via the first flow resistance and the second bearing recess being fluidically connected to the second fluid connection via a second of the flow resistances.

Description

[0081] The invention is explained below with reference to the embodiments shown in the drawing, without any limitation of the invention. Thereby shows:

[0082] FIG. 1 a schematic cross-sectional view of an internal gear fluid machine,

[0083] FIG. 2 a schematic longitudinal sectional view of the internal gear fluid machine,

[0084] FIG. 3 a further schematic longitudinal sectional view of the internal gear fluid machine,

[0085] FIG. 4 a first detailed view of a filler piece of the internal gear fluid machine, as well as

[0086] FIG. 5 a further schematic detailed view of the filler piece.

[0087] FIG. 1 shows a schematic cross-sectional view of an internal gear fluid machine 1, which has a machine housing 2 in which a first gearwheel 3 and a second gearwheel 4 are rotatably mounted. The first gearwheel 3 can also be referred to as a pinion and the second gearwheel 4 as a ring gear. The first gearwheel 3 is rotatably mounted about a first axis of rotation 5 and the second gearwheel 4 is rotatably mounted about a second axis of rotation 6 in the machine housing 2. It can be seen that the first axis of rotation 5 and the second axis of rotation 6 are arranged parallel to and spaced apart from each other, so that the first gearwheel 3 and the second gearwheel 4 therefore have different axes of rotation. The first gearwheel 3 has external toothing 7 and the second gearwheel 4 has internal toothing 8, which mesh with each other in an engagement region 9, i.e. are in engagement with each other.

[0088] The first gearwheel 3 and the second gearwheel 4 together delimit a fluid space 10. The first gearwheel 3 here delimits the fluid space 10 in a radially inward direction and the second gearwheel 4 in a radially outward direction. The fluid space 10 is divided into a first fluid chamber 12 and a second fluid chamber 13 in the circumferential direction by the meshing of the gearwheels 3 and 4 on the one hand and a filler piece 11 on the other. Depending on the direction of rotation of the internal gear fluid machine 1, one of the fluid chambers 12 and 13 is a suction chamber and another of the fluid chambers 12 and 13 is a pressure chamber.

[0089] In the embodiment example shown here, the filler piece 11 is symmetrical in order to enable reversing operation of the internal gear fluid machine 1. The internal gear fluid machine 1 can thus be operated in both directions of rotation. Additionally or alternatively, the filler piece 11 is designed in several parts and has several segments 14 and 15 or 16 and 17. The segments 14 and 15 or 16 and 17 are subdivided in the radial direction. Accordingly, the first segment 14 or 16 is in contact with the first gearwheel 3 and the second segment 15 or 17 is in contact with the second gearwheel 4.

[0090] Between the segments 14 and 15 or 16 and 17 there is a gap 18 or 19, which can be pressurised with fluid. This pressurisation of the fluid forces the segments 14 and 15 or 16 and 17 in the direction of the respective gearwheel 3 or 4. This results in radial compensation of the internal gear fluid machine 1.

[0091] Furthermore, it can be seen that the second gearwheel 4 is surrounded in the circumferential direction at least in some areas, in particular only in some areas, by one or more bearing recesses 20. The bearing recesses 20 are fluidically connected to fluid connections 21 and 22 of the internal gear fluid machine 1 (not shown here), preferably in each case via a flow resistance 23. The flow connections between the respective bearing recess 20 and the fluid connections 21 and 22 can be established via a respective connection channel 24 or 25. The bearing recesses 20 are designed in such a way that they are at least temporarily acted upon by pressurised fluid, for example from the fluid connections 21 and 22, so that they form a hydrostatic bearing for the second gearwheel 4.

[0092] It can be provided that one of the bearing recesses 20 is only fluidically connected to that of the fluid connections 21 and 22 which is assigned to a pressure side of the internal gear machine 1. This is particularly the case if the internal gear machine 1 is not reversible or is only operated in a preferred direction of rotation. However, if the internal gear machine 1 is designed for reversible operation and is operated with intermittently changing directions of rotation, the bearing recesses 20 are preferably fluidically connected to both fluid connections 21 and 22, namely one of the bearing recesses 20 to the fluid connection 21 and another of the bearing recesses 20 to the fluid connection 22. Thus, one of the bearing recesses 20 is always pressurised with the pressure present on the pressure side of the internal gear fluid machine 1, whereas the other of the bearing recesses 20 is pressurised with any pressure, for example with the pressure present on the suction side, which is lower.

[0093] FIG. 2 shows a longitudinal sectional view of the internal gear fluid machine 1. It can be seen that the gearwheels 3 and 4 are mounted axially in the machine housing 3 by means of—purely optional—sealing washers 26. The sealing discs 26 are arranged on opposite sides of the gearwheels 3 and 4 and lie against them in a sealing manner during operation of the internal gear fluid machine 1. First axial apertures 27 and second axial apertures 28 are formed in the sealing discs 26. The axial apertures 27 and 28 completely penetrate the respective sealing disc 26 in the axial direction.

[0094] It can be seen that the axial apertures 27 and 28 each widen in the direction of the gearwheels 2 and 4. For example, the axial openings 27 and 28, as seen in section, are aligned on their side facing the gearwheels 3 and 4 in the radially inward direction with a root circle of the external toothing 7 and/or in the radially outward direction with a root circle of the internal toothing 8, whereby only the former is shown here. At least the axial openings 27 and 28, seen in section, lie between the root circle of the external toothing 7 and the root circle of the internal toothing 8, i.e. do not project beyond them in the radial direction. This ensures a high efficiency of the internal gear fluid machine 1.

[0095] The axial openings 27 are arranged on both sides of the first fluid chamber 12 and the second axial openings 28 on both sides of the second fluid chamber 13. The first fluid chamber 12 is fluidically connected to the first fluid connection 21 via the first axial openings 27. Similarly, the second fluid chamber 13 is fluidically connected to the second fluid connection 22 via the second axial openings 28. Interface channels 29 and 30 are formed in the machine housing 2 for this purpose. The first axial apertures 27 are connected to the respective fluid connections 21 and 22 via the interface channels 29 and the second axial apertures 28 are connected to the respective fluid connections 22 via the second interface channels 30. The sealing discs 26 and the axial openings 27 formed in them can be omitted. In this case, there is a direct flow connection between the interface channels 29 and 30 and the fluid chambers 12 and 13. Of course, only one of the sealing discs 26 can be realised.

[0096] In the embodiment example shown here, one of the connection channels 29 opens directly into the corresponding fluid connection 21 or 22, whereas the other of the connection channels 29 and 30 is connected to the corresponding fluid connection 22 via the respective connection channel 24 or 25. The connection channels 24 and 25 completely overlap the gearwheels 3 and 4 and the sealing discs 26 in the axial direction.

[0097] As shown here, it can be provided that the first interface channels 29 open into the respective fluid connection 21 or 22 in the axial direction and the connection channels 24 and 25 open into the respective fluid connection 22 in the radial direction. The axial openings 27 and 28 are each surrounded by a seal 31 or 32, which ensures a fluid-tight connection of the respective axial opening 27 or 28 to the respective interface channel 29 or 30.

[0098] It can be seen that the axial discs 26 have common dimensions in the axial direction which correspond at least to the dimensions of the gearwheels 3 and 4 in the same direction. Due to these large dimensions in the axial direction, a particularly reliable mounting of the gearwheels 3 and 4 in the machine housing 2 is achieved. In particular, tilting of the axial discs 26 and an associated uneven sealing of the fluid chambers 12 and 13 is reliably prevented.

[0099] FIG. 3 shows a further longitudinal sectional view of the internal gear fluid machine 1. It is clear that the filler piece 11 extends in the circumferential direction as far as the axial apertures 28 and ends in the area of the axial apertures 28. The same naturally applies analogously to the first axial apertures 27. The filler piece 11 has a taper 34 through which it tapers in the axial direction, in the embodiment example shown here on both sides. The taper 34 is formed at the end of the filler piece 11 in the circumferential direction.

[0100] The taper 34 ends—also seen in the circumferential direction—in overlapping with the axial aperture 28, so that the filler piece 11 in overlapping with the axial aperture 28 has dimensions in the axial direction which correspond to the distance of the two sealing discs 26 from each other. Only when overlapping with the axial aperture 28 does the filler piece 11 begin to taper in the direction of its free end. The taper 34 results in optimised flow guidance so that the fluid can flow unhindered into or out of the respective fluid chamber 12 or 13.

[0101] A pressure field is preferably formed away from the seal 32, which can be acted upon by pressurised fluid to apply a force directed towards the gearwheels 3 and 4 to the sealing discs 26. For example, fluid is supplied to the pressure field from one of the fluid connections 21 and 22 or both fluid connections 21 and 22. A corresponding fluid connection can be realised for this purpose. The described design ensures that the fluid chambers 12 and 13 are reliably sealed in the axial direction by the sealing discs 26.

[0102] FIG. 4 shows a first detailed representation of the filler piece 11, which is symmetrical in the circumferential direction, i.e. has at least one axis of symmetry 35 with respect to which it is mirror-symmetrical. A taper 34 is formed at each end of the filler piece in the circumferential direction. The filler piece 11 has an extension in the circumferential direction of at least 180°, preferably more than 180°, in particular at least 190°, at least 200°, at least 210° or at least 220°. In the embodiment example shown here, the extension in the circumferential direction is at least 225°. The described design of the filler piece 11 enables reversible operation of the internal gear fluid machine 1, i.e. operation with any direction of rotation. It is also possible to operate the internal gear fluid machine 1 as a pump and/or as a motor without having to change over. In addition, it ensures reliable sealing of the fluid chambers 12 and 13 from each other in the circumferential direction.

[0103] FIG. 5 shows a further schematic representation of the filler piece 11, whereby the end taper 34 on both sides can once again be seen. This enables a particularly effective inflow of the fluid into the fluid chambers 12 and 13 or an outflow from them. Preferably, the filler piece has constant dimensions in the axial direction away from the taper 34 or the tapers 34.

[0104] FIGS. 1 and 4 also show a return line 36 via which fluid, in particular leakage fluid, can be discharged from the internal gear fluid machine 1 and/or supplied again to the internal gear fluid machine 1 or the respective suction chamber. For example, the return 36 is connected directly to the suction side or the suction chamber. However, it can also be provided that the return flow 36 is fluidically connected to a fluid tank. This fluid tank can be part of the internal gear fluid machine 1, but can also be separate from it. For example, it is fluidically connected to the suction side of the internal gear fluid machine 1. Viewed in the circumferential direction, the return 36 is arranged approximately centrally with respect to the filler piece 11, preferably exactly centrally. Particularly preferably, the return 36 is symmetrical with respect to an imaginary plane which accommodates both the first axis of rotation 5 and the second axis of rotation 6.

[0105] The return 36 has a return recess 37 which reaches through an inner circumferential surface of the machine housing 2 facing the second gearwheel 3, so that the return recess 37 is open in the direction of the gearwheels 3 and 4. In addition, the return 36 has return pockets 38, which are preferably in flow communication with the return recess 37. While the return recess 37, as seen in the axial direction, overlaps the gearwheels 3 and 4, the return pockets 38, as seen in the axial direction, are on both sides of the gearwheels 3 and 4, in particular they are formed on the sides of the sealing discs 26 in the machine housing 2 facing away from the gearwheels 3 and 4.

[0106] The fluid can be discharged via the return 36, i.e. via the return recess 37 and the return pockets 38, and preferably supplied again to the respective suction chamber. For example, the bearing recess 20 opens into the return recess 37. It may be provided that the bearing recesses limiting the bearing recess 20 in the axial direction also limit the return recess 37 in the axial direction. Preferably, however, the bearing recesses 20 are spaced apart from the return recess 37 in the circumferential direction. Preferably, the bearing recesses are symmetrical with respect to the return recess 37, in particular they have the same distance to it.

[0107] The flow resistances 23 are provided in order to limit the amount of leakage fluid, in particular also at a pressure that significantly exceeds an ambient pressure both on the suction side and on the pressure side. These are preferably identical in design and have, for example, a smallest diameter over their respective extension, which is at least 15 l/m2 and at most 75 l/m2 in relation to a displacement volume of the internal gear fluid machine 1. In this way, effective mounting of the second gearwheel 4 in the machine housing 2 can be achieved and, at the same time, a significant reduction in the amount of leakage fluid can be made. One of the flow resistances 23 is fluidically arranged between one of the bearing recesses 20 and the pressure side, and another of the flow resistances is fluidically arranged between another of the bearing recesses 20 and the suction side of the internal gear fluid machine. A fluidic connection between the bearing recesses 20 is preferably only present via unavoidable leakages and/or via the internal gear fluid machine 1 itself, i.e. via the fluid space 10 or at least one or both of the fluid chambers 12 and 13.

[0108] The described design of the internal gear fluid machine 1 enables particularly efficient fluid guidance and a high fluid throughput. In addition, due to the symmetrical design of the filler piece 11, it can be operated reversibly and/or can be pressurised both on its pressure side and on its suction side. Since the filler piece 11 has a multi-part design, a four-segment internal gear fluid machine is realised, which ensures effective sealing of the fluid chambers 12 and 13 from each other in any direction of rotation in the circumferential direction by means of the filler piece 11.