MIXING CHAMBER FOR GENERATING A PUMP CHARGE

Abstract

A mixing chamber for generating a pump charge in a fluid pump has an inner wall defining an inside space. A suction inlet is configured to be connected to a fluid source from which it draws a fluid. A charging inlet is configured to admit a fluid stream into the inside space and thereby to generate the pump charge. An outlet from the inside space is configured to let the fluid in the inside space out of the mixing chamber. The charging inlet includes a first fluid-guiding section configured as a confuser, a second fluid-guiding section in the form of a constriction, and a third fluid-guiding section configured as a diffuser. The constriction is located between the confuser and the diffuser and has the smallest diameter within the charging inlet. The diffuser is formed by an inclined side surface.

Claims

1. A mixing chamber (2) for producing a pump charge in a fluid pump (1), comprising: an inner wall of the mixing chamber (2) extending along a longitudinal axis (L) and defining an inside space (20); a suction inlet that opens into the inside space (20),the suction inlet configured to be connected to a fluid source (4) from which it draws fluid; a charging inlet (22) that opens into the inside space (20), the charging inlet configured to admit a fluid stream into the inside space (20) and thereby to produce the pump charge; and an outlet (23) leading out of the inside space (20), outlet configured to let the fluid present in the inside space (20) out of the mixing chamber (2) wherein the charging inlet comprises: a first fluid-guiding section (24) configured as a confuser; a second fluid-guiding section (25) in the form of a constriction; and a third fluid-guiding section (26) designed as a diffuser; wherein the constriction is located between the confuser and the diffuser and has a smallest diameter in the charging inlet (22), and wherein the diffuser is formed by a side surface (27) inclined at an angle (W) relative to a longitudinal axis (L) of the inside space (20).

2. The mixing chamber (2) according to claim 1 wherein, within the diffuser, the side surface (27) is inclined relative to the longitudinal axis (L) of the inside space (20) at an angle (W) of at least 10 and at most 45.

3. The mixing chamber (2) according to claim 1, wherein a quotient of the flow cross-section (A1) at the constriction and the flow cross-section (A2) of the outlet of the diffuser is at least 0.5 and at most 0.7.

4. The mixing chamber (2) according to claim 1, wherein the confuser has a curved wall (28) configured to deflect the fluid from the radial inlet of the confuser and guide it to the constriction extending transversely thereto.

5. The mixing chamber (2) according to claim 1, wherein the charging inlet (22) is made integrally with the mixing chamber (2).

6. The mixing chamber (2) according to claim 1, further comprising: a first all-round seal (11) arranged in the area of the suction inlet (21) on an outside surface of the mixing chamber (2); a second all-round seal (12) arranged in the area of the outlet (23) on the outside surface of the mixing chamber (2); and a third all-round seal (13) located axially between the first and second all-round seals (11, 12) on the outside surface of the mixing chamber (2).

7. The mixing chamber (2) according to claim 6, wherein the first seal (11) is in the form of a lip seal.

8. The mixing chamber (2) according to claim 1, wherein the outer wall (29) of the diffuser is designed to deflect the fluid into the inside space (20) in the area of the inclined side surface.

9. A pump device for a vehicle transmission, comprising: a fluid pump (1) for conveying fluid from a pump inlet to a pump outlet; and a mixing chamber (2) for charging the pump, wherein, to produce a pump charge, the mixing chamber (2) can be supplied with a fluid stream from the pump outlet and is configured according to claim 1.

10. (canceled)

11. A vehicle with a transmission, the vehicle comprising: a pump device for the vehicle transmission, the pump device comprising: a fluid pump (1) for conveying fluid from a pump inlet to a pump outlet; and a mixing chamber (2) for charging the pump, wherein, to produce a pump charge, the mixing chamber (2) can be supplied with a fluid stream from the pump outlet and is configured according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Advantageous embodiments of the invention, which are explained in what follows, are illustrated in the drawings in which the same or similar elements are denoted by the same indexes, and which show:

[0026] FIG. 1: A highly abstract schematic view of a pump arrangement for a vehicle transmission;

[0027] FIG. 2: A schematic sectioned view of a mixing chamber according to the invention;

[0028] FIG. 3: A schematic perspective representation of the mixing chamber according to the invention;

[0029] FIG. 4: A further schematic sectioned view of the mixing chamber according to the invention;

[0030] FIG. 5: A schematic view from above, of the mixing chamber according to the invention;

[0031] FIG. 6: A further schematic sectioned view of the mixing chamber according to the invention; and

[0032] FIG. 7: A schematic side view of the mixing chamber according to the invention.

DETAILED DESCRIPTION

[0033] FIG. 1 shows as an example a pump device for producing a hydraulic pressure in a vehicle transmission. Such a pump device can also be used for other applications and also for conveying other fluids. The pump device comprises a fluid pump 1 in the form of a hydraulic pump, and a mixing chamber 2 which is connected upstream from the fluid pump 1 and is provided in order to produce a pump charge. The pump conveys pressurized hydraulic fluid from a fluid source 4 of the transmission in the form of a reservoir to a hydraulic consumer 7 of the transmission. The hydraulic consumer can for example consist of a hydraulic actor and/or a lubrication point in the transmission. For example, with the hydraulic fluid conveyed by the fluid pump 1 shifting elements of the transmission can be actuated in order to shift gears of the transmission.

[0034] In the present case the fluid pump 1 delivers a non-adjustable delivery volume and is for example in the form of a vane pump. The delivery volume of the fluid pump 1 depends essentially on the rotation speed of the pump, i.e., the rotation speed at which the fluid pump 1 is driven. High pump rotation speeds increase the risk that cavitation may take place within the fluid pump 1. The fluid pump 1 draws the hydraulic fluid from the fluid source 4 via a suction line 5. The suction line 6 runs through a filter 6 and the mixing chamber 2. Connected downstream from the fluid pump 1 there is a valve 3 by way of which the hydraulic fluid can be led on the one hand in the direction toward the consumer 7 and on the other hand, via the return line 81, back into the mixing chamber 2 in order to produce the pump charge. The valve 3 is in particular in the form of an over-pressure valve. The hydraulic fluid delivered is passed back into the mixing chamber 2 automatically if the hydraulic pressure downstream from the valve 3 exceeds a certain pressure or if not all of the quantity of fluid delivered by the fluid pump 1 is needed. Only the amount of hydraulic fluid not required is so returned. The consumer 7 is supplied at all times with a sufficient delivery quantity at a sufficient pressure.

[0035] The concept of pump charging is already known as such, and for that reason it will be explained only briefly in what follows. The mixing chamber has an inside space 20 into which a suction inlet 21 and a charging inlet 22 open. The suction inlet 21 is connected to the fluid source 4 from which it is supplied with hydraulic fluid. The charging inlet 22 is connected to the return line 81 leading back from the valve 3. If necessary, the charging inlet 22 can therefore be supplied with some of the hydraulic fluid conveyed by the fluid pump 1. The outlet 23 of the mixing chamber 2 is connected to the inlet of the fluid pump 1. Thus, the hydraulic fluid drawn from the fluid source 4 passes, via the inlet 22, first into the inside space 20 of the mixing chamber 2. Here, this flow is called the suction flow. In addition, when the valve 3 is appropriately set the pressurized hydraulic fluid passes into the inside space 20 via return line 81 and the charging inlet 22. Here, that flow is called the charging flow. In the inside space 20 the suction flow and the charging flow are mixed with one another, so the charging flow gives up at least some of its kinetic energy to the suction flow. Consequently, the suction flow entering the mixing chamber is accelerated toward the fluid pump 1. That reduces the energy needed by the fluid pump 1 for conveying the hydraulic fluid without having to reduce the rotation speed of the pump. When suction charging is used the efficiency of the fluid pump 1 is improved. The valve 3 is preferably arranged in a valve plate of a hydraulic control unit of the vehicle transmission. The lines shown in FIG. 1 for the hydraulic fluid can be arranged in an associated duct plate and/or the valve plate of the hydraulic control unit. The fluid flows from the mixing chamber 2 to the consumer 7 and from the valve 3 to the mixing chamber 2 are indicated by arrows.

[0036] FIGS. 2 to 7 show various views of the mixing chamber 2 according to the invention as it is used in the pump arrangement of FIG. 1. In FIGS. 2, 4 and 6 the mixing chamber 2 is in each case shown sectioned longitudinally along the longitudinal axis L. In FIG. 5 the mixing chamber 2 is shown as viewed from above. FIG. 3 shows a perspective view of the mixing chamber and FIG. 7 shows a side view of the mixing chamber 2.

[0037] The mixing chamber 2 is provided in order to produce a pump charge in the fluid pump 1 shown in FIG. 1, and for that purpose comprises an essentially tubular inside space 20 formed by an inner wall of the mixing chamber 2, a suction inlet 21 that opens into the inside space 20 which inlet is connected to draw fluid from the fluid source 4 in FIG. 1, a charging inlet 22 that opens into the inside space 20, which conveys a fluid stream from the return line 81 into the inside space 20, and an outlet leading out of the inside space 20, which lets the fluid in the inside space 20 out of the mixing chamber 2 and into the fluid pump 1. The suction inlet 21 and the outlet 23 are at opposite ends of the mixing chamber 2, which extends straight along the longitudinal axis L. The inside space also extends straight along the longitudinal axis L.

[0038] The outlet 23 and the suction inlet 21 are preferably each in the form of plug-in flanges. In that way the mixing chamber 2 can on the one hand be plugged into a suction duct of the fluid pump 1 and the return line 81 in the duct plate 8 of a hydraulic control unit, and on the other hand into a suction duct of a valve plate 9 of a hydraulic control unit. On the outside of the mixing chamber 2 an at least partially surrounding collar can be provided, by which an axial end-stop for positioning the mixing chamber 2 in its fitted position is formed. The collar can have an axial extension that corresponds to the width of an intermediate sheet Z located between the duct plate 8 and the valve plate 9. In that way the collar and hence the mixing chamber 2 can be fixed in an opening of the intermediate sheet Z between the duct plate 8 and the valve plate 9.

[0039] Furthermore, the mixing chamber 2 comprises a first all-round seal 11 which is arranged in the area of the suction inlet 21 on an outside surface of the mixing chamber 2, a second all-round seal 12 arranged in the area of the outlet 23 on the outside surface of the mixing chamber 2, and a third all-round seal 13 arranged axially between the first and second all-round seals 11, 12 on the outside surface of the mixing chamber 2. The first seal 11 is in the form of a lip seal and rests in fluid-sealing contact radially between the mixing chamber 2 and the valve plate 9. The second and third seals 12, 13 are in the form of O-rings. The third seal 13 is in fluid-sealing contact radially between the mixing chamber 2 and the duct plate 8. The fluid flowing into the mixing chamber 2 and out of the mixing chamber 2 is indicated by arrows.

[0040] FIG. 3 shows a perspective view of the mixing chamber 2 according to the invention as seen from below, i.e., looking into the suction inlet. The mixing chamber 2 is made in one piece and can be produced in plastic, for example by an injection-molding process. Thus, the suction inlet 21, the charging inlet 22 and the outlet 23 are integral parts of the one-piece mixing chamber 2.

[0041] FIG. 4 shows the mixing chamber 2 according to the invention seen along a second longitudinal section, wherein the picture plane of FIG. 4 is rotated by 180 relative to the picture plane of FIG. 2. The charging inlet 22 consists of a first fluid-guiding section 24 in the form of a confuser, a second fluid-guiding section 25 that forms a constriction, and a third fluid-guiding section 26 in the form of a diffuser. The constriction is located between the confuser and the diffuser and has the smallest diameter within the charging inlet 22. For a better understanding the divisions of the charging inlet 22 are indicated by horizontal broken lines. Furthermore, it can be seen in FIG. 4 that the diffuser has a side surface 27 which is inclined at an angle relative to the longitudinal axis L of the inside space 20. The confuser has a curved wall 28 which deflects the fluid from its radial entry into the confuser and guides it to the constriction positioned transversely thereto.

[0042] The view of the mixing chamber 2 seen from above, shown in FIG. 5, makes clear the configuration of the charging inlet 22, in particular the diffuser. The charging inlet 22 is made in one piece with the mixing chamber 2. The charging inlet 22 opens along the inner wall of the mixing chamber 2 into the inside space 20. As can be seen particularly well in FIGS. 3 and 5, the inside space 20 of the mixing chamber 2 is shaped to assist flow so that the flow losses are small. The outside wall 29 of the diffuser deflects the fluid flowing into the inside space 20 through the suction inlet 21 in the area of the inclined side surface 27 and gives rise to a spoiler effect.

[0043] FIG. 6 shows the mixing chamber 2 according to the invention in a third longitudinal section, wherein the picture plane of FIG. 6 is rotated by 90 relative to the picture plane of FIG. 2 or FIG. 4. In FIG. 6 the structure of the diffuser and the constriction are shown particularly clearly. The side surface 27 inclined relative to the longitudinal axis L of the inside space 20 within the diffuser has an angle W of 24. Furthermore, a quotient of the flow cross-section A1 at the constriction and the flow cross-section at the outlet of the diffuser is equal to 0.56. By virtue of this structure of the charging inlet 22, a unilateral pressure increase, and optimized guiding of the fluid, in particular a targeted deflection, are achieved. This reduces the cavitation.

[0044] FIG. 7 shows a side view of the mixing chamber 2, particularly from the perspective according to FIG. 6. The charging inlet 22 formed in the sidewall of the mixing chamber 2 is located between the first and third seals 11 and 13. In this case, owing to the perspective view only the confuser of the charging inlet 22 can be seen.

INDEXES

[0045] 1 Fluid pump [0046] 2 Mixing chamber [0047] 20 Inside space [0048] 21 Suction inlet [0049] 22 Charging inlet [0050] 23 Outlet [0051] 24 First fluid-guiding section [0052] 25 Second fluid-guiding section [0053] 26 Third fluid-guiding section [0054] 27 Inclined side surface [0055] 28 Curved wall [0056] 29 Outer wall of the diffuser [0057] 3 Valve [0058] 4 Fluid source [0059] 5 Suction line [0060] 6 Filter [0061] 7 Hydraulic consumer [0062] 8 Duct plate [0063] 9 Valve plate [0064] 10 Intermediate sheet [0065] 11 First all-round seal [0066] 12 Second all-round seal [0067] 13 Third all-round seal [0068] A1 Flow cross-section at the constriction [0069] A2 Flow cross-section at the outlet of the diffuser [0070] L Longitudinal axis [0071] W Angle [0072] Z Intermediate sheet