EP1141551A1

EP1141551A1 - Pump assembly comprising two hydraulic pumps

Info

Publication number: EP1141551A1
Application number: EP99964582A
Authority: EP
Inventors: Egon Birkenmaier; Günter Fischer
Original assignee: Mannesmann Rexroth AG
Current assignee: Bosch Rexroth AG
Priority date: 1998-12-24
Filing date: 1999-12-16
Publication date: 2001-10-10
Anticipated expiration: 2019-12-16
Also published as: WO2000039465A1; ATE226283T1; EP1141551B1; US6579070B1

Abstract

A pump assembly which comprises a vane pump and a second hydraulic pump driven together with this vane pump. The vane pump has a suction region in which first pressure spaces between the vanes and second, rear pressure spaces behind the vanes become larger and a pressure region in which the pressure spaces become smaller and in which the pressure spaces are fluidically connected to a pressure outlet. This vane pump is intended particularly for supplying operating cylinders of a hydromechanical transmission of a motor vehicle with pressure fluid under relatively high pressure. The second hydraulic pump has positively driven displacement elements and is intended for supplying a circuit having a relatively low system pressure, in particular a lubricating-oil circuit of the motor vehicle, with pressure fluid. So that the vane pump also begins to deliver at low outside temperatures and with highly viscous pressure fluid even at low rotational drive speeds, the rear pressure spaces of the vane pump are connected in the suction region to the pressure outlet of the second hydraulic pump.

Description

description

Pump arrangement with two hydraulic pumps

5 The invention is based on a pump arrangement which, according to the preamble of claim 1, a vane cell pump, which is intended in particular for supplying stela cylinders of a hydromechanical engine of a motor vehicle with a pressure fluid under high pressure, and comprises a second hydraulic pump, the displacement elements of which are positively guided and the supply

I O of a circuit with a low system pressure, especially one

Lubricating oil circuit of the motor vehicle with which pressure fluid is used. The two hydraulic pumps therefore work with the same operating medium.

A pump arrangement which comprises a wing cell pump and a second hydropump, the displacement elements of which are positively guided, is already known from EP 0 128 969 A1. There, the oil flow from the wing cell pump is used to supply pressure to a power steering system. The second hydraulic pump is a radial piston pump, the oil flow of which is used for a device for leveling the vehicle. The two hydraulic pumps of the known pump arrangement are located in two pressure fluid circuits, which only the oil reservoir has in common.

A vane cell pump generally has a suction area in which first pressure spaces between the wings and second, rear pressure spaces 25 behind the wings increase and thereby absorb pressure fluid. The pressure spaces are reduced in a pressure area, as a result of which pressure fluid is displaced to a pressure outlet. For a vane cell pump to function properly, it is necessary for the vanes, which are guided in radial slots in a rotor, to bear against the outside of a cam ring. Centrifugal forces are used for such a system uses, which attack the wings and for their effect a substantial pressure equalization between the front side of the cam ring and the back of the wings in the slots is a prerequisite. This requirement is met by connecting the rear pressure chambers in the pressure area to the pressure outlet of the pump. In the suction area, both the first pressure spaces and the second pressure spaces are usually connected to the suction inlet of the wing cell pump, so that the same pressures prevail in them.

The centrifugal forces required to place the wings on the cam ring are greater, the higher the viscosity of the pressure fluid, which increases with falling temperature. This means that a vane cell pump of a conventional type only begins to deliver at a higher speed the lower the temperature of the pressure fluid. In particular, the engine and gear oil of a motor vehicle, in particular an agricultural tractor, can become so viscous at low ambient temperatures that the wing cell pump only begins to work at unacceptably high speeds.

The invention has for its object to develop a pump assembly according to the preamble of claim 1 so that proper operation is possible even at low ambient temperatures and thus high viscosity of the pressure fluid.

This object is achieved according to the invention in a pump arrangement having the features from the preamble of patent claim 1 in that the rear pressure chambers of the wing cell pump in the suction region are connected to the pressure outlet of the second hydraulic pump. Since the displacement elements of the second hydraulic pump are positively guided, the second hydraulic pump begins to deliver, regardless of the viscosity of the pressure fluid, when it is driven becomes. The pressure that builds up at its pressure outlet is then also present in the rear pressure chambers of the wing cell pump and generates a force on the vanes that, in addition to the centrifugal force, presses the vanes radially outwards against the cam ring. The system pressure in the circuit, which is supplied by the second hydraulic pump, is relatively low, for example in the range of 5 bar. The frictional force between the wings and the cam ring therefore increases only slightly in the suction area of the vane cell pump, so that the wear on these parts remains low.

From DE-AS 17 28 276 a pump arrangement comprising two hydraulic pumps is already known, in which the rear pressure chambers on the wings of a first hydraulic pump designed as a wing cell pump are connected in their suction area to the pressure outlet of the second hydraulic pump. However, the second hydraulic pump here is also a vane cell pump, which fails when the viscous fluid is highly viscous, so that the problem underlying the invention is not eliminated in the pump arrangement known from DE-AS 17 28 276.

Advantageous embodiments of a pump arrangement according to the invention can be found in the subclaims.

For example, the wing cell pump is preferably one with a variable displacement volume, since the consumption of unusable energy can thereby be reduced in comparison with a wing cell pump with a constant displacement volume. Since it is particularly important that the individual components are inexpensive in addition to economical use of the primary energy when used in motor vehicles, the wing cell pump is advantageously directly controlled and goes as far as possible with its displacement volume when a set maximum pressure is reached back that only the small amount lost due to internal leakage is replaced at the maximum pressure. The power loss, which is then given by the product of the maximum pressure and the amount of leakage, is low because the amount of leakage is small.

The second hydraulic pump is advantageously a gear pump, in particular a filler-less internal gear pump, which works quietly, is inexpensive to manufacture and can also be designed in such a way that it can be combined with the vane cell pump to form a structural unit without great effort, such as this is stated in claim 6.

Advantageous configurations of such a structural unit can be found in the further subordinate claims.

Three exemplary embodiments of a pump arrangement according to the invention are shown in the drawings. The invention will now be explained in more detail with reference to the figures of these drawings.

1 shows the first exemplary embodiment in a more schematic form,

2 shows a longitudinal section including the axis of the drive shaft through the second exemplary embodiment, in which the vane cell pump and the second hydraulic pump designed as an internal gear pump are combined to form a structural unit with a common control part fixed to the housing,

FIG. 3 shows a section along the line III-III from FIG. 2,

FIG. 4 shows a section along the line IV-IV from FIG. 2,

FIG. 5 shows a section along the line V-V from FIG. 2,

6 shows a longitudinal section including the axis of the drive shaft the third exemplary embodiment, which differs from the second exemplary embodiment essentially in the design of the control grooves and in the arrangement of the pressure connections in the control part, FIG. 7 shows a section along the line VIII-VII from FIG. 6, 5 FIG. 8 shows a longitudinal section through the third exemplary embodiment the line

VIM-VMI of FIG. 7, FIG. 9 is a view of the end face of the control part on the fly cell pump side and FIG. 10 is a view of the control part in the direction of the two parallel pressure connections.

According to Figure 1, a vane cell pump 10 suck via a suction inlet 11 and a second hydraulic pump 12, which e.g. is designed as a radial piston pump, the radial pistons of which bear against an eccentric under spring pressure, via a

15 suction inlet 13 pressurized fluid from a tank 14 which through the housing of the transmission of a motor vehicle, e.g. an agricultural tractor. Because the radial pistons of the radial piston pump 12 are pressed against the eccentric by springs, the radial pistons can be referred to as positively driven displacement elements. The radial piston pump outputs 15 via a pressure outlet

20 pressure fluid in a lubricating oil circuit 16 of the motor vehicle transmission, the pressure in the pressure outlet 15 being 4 bar to 5 bar when the pressure fluid has reached operating temperature. The gear oil flows from the lubricating oil circuit 16 back into the tank 14. A pressure limiting valve 19 secures the pressure outlet 15 of the hydraulic pump 12.

25

Various hydraulic consumers 18 are supplied with pressure fluid from the air cell pump 10 via a pressure outlet 17, these being, for example, actuating cylinders of a hydrostatic device belonging to the transmission of the motor vehicle and hydraulic actuators of clutches. The vane cell pump 10 and the second hydraulic pump 12 are driven via a drive shaft 20 common to them, which has an axis 21 and on which a rotor 22 is fastened in a rotationally secure manner. The circumference of the rotor is

5 moderately radial slots 23 distributed in which wings 24 are guided. These protrude radially beyond the circumference of the rotor 22 and are in contact with a cam ring 25 with a circular-cylindrical cam curve, the axis of which has a distance E from axis 21 of the drive shaft 20 that can be varied between zero and a maximum value. The wing cell pump 10 is thus a wing cell pump with a variable

I O Displacement. The vanes 24 form first pressure spaces 27 between them and, on their rear side facing the bottom of the slots 23, second, rear pressure spaces 28 in the slots 23.

On the side of the cam ring 25 and on the rotor 22 there is a control disk 32, which has a total of four control grooves open towards the rotor 22. A radially outer suction groove 33 is fluidly connected to the suction inlet 11 and is mounted in the control disk 32 such that the first pressure spaces 27 are in register with it as they enlarge. It should be noted that in the view according to FIG. 1 the rotor is driven counterclockwise. 20 A further suction groove 34 is located radially further inward than the suction groove 33, with which the second pressure spaces 28 are in overlap as they enlarge. It is essential that the suction groove 34 is not connected to the suction inlet 11 of the vane cell pump 10, but to the pressure outlet 15 of the radial piston pump 12. Thus, the pressure spaces 28 in the suction area of the vane cell pump 10, in which their volume increases, are acted upon by the pressure prevailing at the pressure outlet 15 of the radial piston pump 12 and pressed outward against the lifting ring 25. In the pressure area of the air cell pump 10, in which the pressure spaces 27 and 28 decrease, they overlap with a radially outer pressure groove 35 and with a radially inner one Pressure groove 36. These two pressure grooves are fluidly connected to one another and to the pressure outlet 17, so that the wings 24 are subjected to the same pressure in the pressure area on their front side and on their rear side.

5 If the vehicle, in which the hydraulic pumps 10 and 12 and the hydraulic consumers 16 and 18 are located, is at a standstill and at low ambient temperatures, the pressure fluid with which the work is carried out is highly viscous. Because the displacement elements of the hydraulic pump 12 are positively guided, this pump immediately begins to deliver the highly viscous pressure fluid when the drive

I O shaft 20 begins to rotate. In the pressure outlet 15, pressure builds up, by means of which the vanes 24 of the wing cell pump 10 are pressed radially outward in the suction area, so that the wing cell pump also promotes the pressure fluid even at low speeds of the drive shaft 20. It should also be pointed out that the pressure at the pressure outlet 15 of the hydraulic pump 12 is all the higher

15, the higher the viscosity of the pressurized fluid. Because the hydraulic resistances of the lubricating oil circuit cause a higher load pressure, the higher the viscosity of the pressure fluid. On the other hand, the additional force necessary in addition to the centrifugal force, which ensures that the vanes 24 of the vane cell pump 10 rest securely on the lifting ring 25, the greater the viscosity

20 of the pressure fluid. An additional force, depending on the viscosity of the pressure fluid, on the vanes 24 of the wing cell pump 10 is thus obtained without further measures.

In the embodiment according to FIGS. 2 to 5, a fly cell pump 10 and 25, a second hydraulic pump designed as a filler-free internal gear pump 40 are combined to form a structural unit, which are located in a multi-part common housing 41 and are driven by a single drive shaft 42. The housing is composed of a cup-shaped housing part 43 and a cover-shaped housing part 44. Located in the bottom of the housing part 43 there is a ball bearing 45 in which the drive shaft 42 is mounted. This protrudes with one end beyond the bottom of the housing part 43 and is provided with serration at this end. A gear (not shown in more detail) for driving the double pump can be pushed onto this end. On

5 of the drive shaft 42, the rotor 22 of the vane cell pump 10 and an externally toothed gear 47 of the internal gear pump 40 are secured against rotation at an axial distance from one another. The gearwheel 47 is located in a circular-cylindrical pump chamber, which is fixed between a side plate 48 resting on the bottom of the housing part 43 and a side plate 48 like the side plate 48.

I O housing arranged control part 49, which essentially occupies the space between the rotor 22 and gear 47 and which extends with an annular cylindrical collar to the side window 48, is formed. The rotor 22 of the vane cell pump 10 is located in a further circular-cylindrical pump chamber which is formed between the cover 44 and the control part 49, which is connected to a circular-cylindrical

I5 see extension extends to cover 44 and overlaps a centering collar on it. In the pump chamber of the vane cell pump 10 there is also the cam ring 25, which is supported against one during normal operation by a compression spring 50, which is supported by a spring plate 51 on the cam ring 25 and a second spring plate 52 on an adjusting screw 53 for the maximum operating pressure the

20 compression spring 50 diametrically opposite adjusting screw 54 is pressed for the maximum stroke volume. In operation, the rotor rotates in the direction of arrow A from FIG. 3 counterclockwise, the pressure range, viewed continuously in the direction of rotation, being between the adjusting screw 54 and the compression spring 50. The pressure generated and perpendicular to the connection

25 line between the adjusting screw 54 and the compression spring 50 force component is absorbed by the height adjustment screw 55, which determines the position of the cam ring perpendicular to the connecting line between the adjusting screw 54 and the compression spring 50. Inside, the vanes 24, which are guided radially in the slots 23 of the rotor 22, rest on the cam ring. In Figure 3 you can see between the wings the pressure chambers 27 and on the back of the wings the pressure chambers 28.

A radially open large recess 60 in the control part 49, over which

5, the housing part 43 has an opening 61, forms the suction inlet for both the wing cell pump 10 and the internal gear pump 40. The outer suction groove 33 of the wing cell pump 10 extends axially between the recess 60 and the end face of the control part 49 facing the rotor 22 the suction groove 33 is located approximately on the outer circumference of the rotor 22.

I O namely in the area of the bottom of the slots 23 opens into the pump chamber of the vane cell pump 10, the inner suction groove 34 which, viewed in the axial direction, extends into the control part 49 beyond the center of the recess 60. The recess 60 does not extend radially to the suction groove 34. There is no fluid connection between the suction groove 34 and the recess 60, that is to say the

15 Suction inlet of the two pumps. Approximately opposite the suction grooves 33 and 34, the inner pressure groove 36, over which the rear pressure spaces 28 pass, and the outer pressure groove 35, towards which the pressure spaces 27 open, are introduced into the control part 49. The two pressure grooves also extend deep into the control part 49. The control part 49 is located in the same radial

20 ne, in which the recess 60 also lies, a radial bore 62 which is continued outwards through a corresponding bore 63 in the housing part 43 and internally cuts the two pressure grooves 35 and 36 close to one end thereof. The bores 62 and 63 form the pressure outlet of the wing cell pump 10, with which both pressure grooves 35 and 36 are thus fluidly connected.

23

The externally toothed gear 47 of the internal gear pump 40 is surrounded on the outside by an internally toothed ring gear 64, which is rotatably mounted on the outer circumferential surface in the control part 49 eccentrically to the gear 47. It has one tooth 65 more than the gear 47. Its teeth 66 and the teeth 65 of the Gear 64 slide along each other and, as the positively driven displacement elements of the gear pump 40, form pressure spaces between them which increase in operation in the suction area and decrease in the pressure area. In the suction area, the pressure spaces are open to a suction groove 67 which is between

5 see the pump chamber of the internal gear pump 40 and the recess 60 located wall of the control part 49 breaks through. The suction groove 67, approximately opposite, is introduced into the control part radially outside the pressure grooves 35 and 36 of the vane cell pump 10, a pressure groove 68 of the internal gear pump 40. Axially, the pressure groove 68 extends beyond the radial plane in which the radial bore 62

I O and the recess 60 of the control part 49 lie in this. A radial bore 69 in the control part 49, which is located in the radial plane and which is open on the inside to the pressure groove 68, and a radial bore in the housing part 43, which is aligned with the radial bore 69, form the pressure output of the internal gear pump 40. As can be seen in particular from FIGS. 4 and 5 , the pressure groove 68 ends in

15 peripheral direction at a distance from the radial bore 62 of the control part 49, so that there is no fluidic connection between the pressure outputs of the two pumps.

In the vicinity of the other end of the pressure groove 68 a bore 71 20 extends from the latter, which is introduced tangentially from the outside into the control part 49, which is connected to the

Pressure grooves 35 and 36 of the air cell pump passes and the tangential opens into one end of the suction groove 34 of the air cell pump 10. This suction groove 34 of the vane cell pump 10 is fluidly connected to the pressure groove 68 of the internal gear pump 40. The rear pressure chambers 28 of the vane pump 25 are thus filled with fluid in the suction area from the pressure outlet of the internal gear pump 40, so that there is at least approximately the same pressure in them as in the pressure outlet of the internal gear pump 40. The type of opening of the bore 71 in the suction groove 34 contributes to the fact that a possible pressure loss between the pressure groove 68 and the suction groove 34 is only slight. The Bore 71 lies in a radial plane which goes centrally through the recess 60 and the bores 62 and 69 of the control part 49. It meets the suction groove 34 because it extends axially into the control part 49 beyond this radial plane. However, it is also conceivable to make the suction groove 34 less deep and the bore 71

5 to be arranged in a radial plane closer to the pump chamber of the air cell pump or also to run so obliquely with respect to a radial plane that its starting point at the pressure groove 68 is at a greater distance from the pump chamber of the air cell pump 10 than its mouth into the suction groove 34 4 and 5 based on the position of the different

I O nen suction and pressure grooves recognizable, suction and pressure area of the vane cell pump 10 are slightly rotated relative to the suction and pressure area of the internal gear pump 40. As a result, on the one hand, the suction groove 34 has come into a somewhat more favorable position in order to create the connecting channel between it and the pressure groove 68. On the other hand, the pressure grooves 35 and 36 of the wing cell pump 10

15 migrated somewhat from one end of the pressure groove 68, so that between them and the recess 60 there is enough material on the control part 49 to insert the connecting channel 71 between the suction groove 34 and the pressure groove 68 into the material.

In the embodiment according to FIGS. 6 to 10, too, an adjustable vane cell pump 10 and a second hydraulic pump designed as a filler-less internal gear pump 40 are combined to form one structural unit. Both pumps are driven by a single drive shaft 42. The housing 41 is somewhat different from the second embodiment by the central control part 49, which in the

25 NEN front side has the pump chamber for the rotor 22 with the vanes 24 located in slots 23 and for the cam ring 25 of the vane cell pump 10 and in the opposite front side the pump chamber for the externally toothed gear 47 and the internally toothed gear 64 of the internal gear pump 40, as well as the cover 44, with which the pump chamber of the wing cell pump is connected is closed, and a further cover 74, with which the pump chamber of the internal gear pump is closed. The further cover 74 fulfills the two functions which, in the second exemplary embodiment, have the side window 48 and the bottom of the housing pot 43. A ball bearing 45 is accordingly in it

5 used, in which the drive shaft 42 is mounted. Except in the ball bearing 45, the drive shaft 42, as in the second exemplary embodiment, is also in a slide bearing 75, which is inserted into a central bore 76 of the control part 49 and extends a certain distance from the end of the bore 76 on the vane cell pump side into the control part. The two covers 44 and 74 and that

I O control part 49 are held together in a manner not shown by long machine screws.

The adjustment mechanism of the vane cell pump 10 of the third exemplary embodiment is the same as in the second exemplary embodiment, so that it need not be discussed in more detail here. The gear set 47, 64, which is used in the third exemplary embodiment for the internal gear pump 40, is smaller in diameter than the gear set of the second exemplary embodiment.

In operation, the drive shaft 42, viewed in FIG. 7, rotates clockwise and, viewed in FIG. 9, counterclockwise.

In addition to the design of the cover 74 in front of the pump chamber of the internal gear pump 40, the third exemplary embodiment differs substantially from the second exemplary embodiment in the design of the cavities in the control part 25. The suction inlet for the two pumps 10 and 40 is again formed, as in the second exemplary embodiment, by a radially open, large-area recess 60 in the control part 49. However, this has a strong asymmetry in the section according to FIG. 7, so that in an area in which one of three machine screws passes through the control part. hen should, material for a bore 77 is available without interruption. Extending axially between the cutout 60 and the end face of the control part 49 facing the rotor 22 is the outer suction groove 33 of the wing cell pump 10, which looks essentially the same as in the second exemplary embodiment and is again located approximately on the outer circumference of the rotor 22. Further inside, namely in the area of the bottom of the slots 23, the inner suction groove 34 opens into the pump chamber of the wing cell pump 10. The recess 60 does not extend radially to the suction groove 34. There is no fluidic connection between the suction groove 34 and the recess 60, So the suction inlet of the two pumps. As can be seen in particular from FIG. 8, in which the inner suction groove 34 is shown in broken lines, the inner suction groove in the third exemplary embodiment does not extend over its entire length in the axial direction to beyond the center of the recess 60 into the control part 49. Rather, the inner suction groove 34 has an area 78 of less depth and a rear area 79 of greater depth when viewed in the direction of rotation of the rotor. Only this area of greater depth extends in the axial direction to beyond the center of the cutout 60 into the control part 49 and is visible in the section according to FIG. The control part 49 of the third exemplary embodiment is more stable than a design with a large depth of the inner suction groove over its entire length.

Approximately opposite the suction grooves 33 and 34, the inner pressure groove 36 of the vane cell pump 10, over which the rear pressure spaces 28 pass, and the outer pressure groove 35, towards which the pressure spaces 27 open, are introduced into the control part 49. The two pressure grooves also each have an area 82 and 83 of shallow depth and a rear area 84 and 85 of greater depth, viewed in the direction of rotation of the rotor, in which they extend deeply beyond a radial plane running in the middle of the suction inlet, the is identical to the sectional plane according to FIG. 7, protrude into the control part 49. In FIG. 10, the inner pressure groove 36 is merged with the flatter region 83 and the deeper region 85. draws. In the control part 49 there is a stepped connecting bore 62 which runs tangentially to the axis of the drive shaft 42 and which corresponds in function to the bore of the second exemplary embodiment provided with the same reference number and which has the two pressure grooves 35 5 and 36 in its area 84, 85 cuts to greater depth.

As in the second, the teeth of the gears 47 and 64 of the internal gear pump 40 slide along one another in the third exemplary embodiment and form pressure spaces between them, which are located in the

I O Increase operation in the suction area and reduce it in the pressure area. In the suction area, the pressure spaces are open to a suction groove 67, which breaks through a wall of the control part 49 located between the pump chamber of the internal gear pump 40 and the recess 60. The suction groove 67 is approximately opposite one another in approximately the same angular range in which the pressure grooves 35 and 36

15 of the wing cell pump 10, a pressure groove 68 of the internal gear pump 40 is introduced into the control part. This pressure groove 68 is now not located radially outside of the pressure groove 35, but is at least partially on the same diameter as the pressure grooves 35 and 36. Like the pressure grooves 35 and 36, the pressure groove 68 also has a region 86 of shallow depth which corresponds to the deeper areas.

20 chen of the pressure grooves 35 and 36 axially opposite, and a region 87 of great depth, which extends axially beyond the radial plane mentioned above and which is axially opposite the flatter regions of the pressure grooves 35 and 36. A in the said radial plane and parallel to the connection hole 62 of the air cell pump 10 extending connection hole 69 in the control part 49, which in

25 corresponds to the function of the bore of the second exemplary embodiment provided with the same reference number, the inside of the lower region 87 of the pressure groove 68 is open. In the deeper areas of the pressure grooves 35 and 36 axially opposite shallower area 86 of the pressure groove 68 there is of course no fluidic connection to the connection bore 62 or to one of the pressure grooves 35, 36. Thus If the two connection bores 62 and 69 are arranged close to one another in the same radial plane, the presence of a flat and a deep region in the pressure grooves 35, 36 and 68 ensures that on the one hand the correct fluidic connections between the pressure grooves 35, 36 and 68 on the one hand and the connection bores 62 and 69 are produced on the other hand and that on the other hand the pressure groove 68 can lie on the diameter of the pressure grooves 35 and 36, so that little space is required in the radial direction.

If, as in the second exemplary embodiment, the pressure groove 68 is located radially outside of the pressure groove 35, then with an arrangement of the connection bores 62 and 69, as in the third exemplary embodiment, only the pressure groove 68 itself should have areas of different depths. The pressure grooves 35 and 36 could extend over their entire length beyond the radial plane under consideration. However, regions of the pressure grooves 35 and 36 of different depths also appear advantageous since improved stability of the control part 49 can then be expected.

As in the second exemplary embodiment, in the third exemplary embodiment, a bore 71 extends from the pressure groove 68, which is introduced into the control part 49 through the connecting bore 69 and running parallel to it and lying in the radial plane mentioned, and which therefore is located on the flat regions 8- 2 and 83 of the pressure grooves 35 and 36 of the air cell pump passes and which opens into the lower region 79 at one end of the suction groove 34 of the air cell pump 10. This suction groove 34 of the vane cell pump 10 is fluidly connected to the pressure groove 68 of the internal gear pump 40. The rear pressure chambers 28 of the vane cell pump 10 are thus filled with fluid in the suction area from the pressure outlet of the internal gear pump 40, so that the pressure in the internal gear pump 40 is at least approximately the same as in the pressure outlet. Because the connecting bore 71 is made through the connecting bore 69, the machining length is shorter. There is no need for that Close the hole later and cut a thread necessary for screwing in a plug.

Claims

claims

1. Pump arrangement comprising a wing cell pump (10), which is provided for the supply of one or more hydraulic consumers (18), in particular of stela cylinders of a hydromechanical transmission of a motor vehicle, with a pressurized fluid under high pressure, which has a suction area in which enlarge the first pressure spaces (27) between the wings (24) and second, rear pressure spaces (28) behind the wings (24), and have a pressure area in which the pressure spaces (27, 28) decrease and in which the pressure spaces (27 , 28) are fluidly connected to a pressure outlet (62, 63), and a second hydraulic pump (40) driven together with the wing cell pump (10), the displacement elements (65, 66) of which are positively guided and which are used to supply a circuit with a low pressure System pressure, in particular a lubricating oil circuit of the motor vehicle, with the pressurized fluid via a second pressure outlet (69, 70), characterized in that di e rear pressure chambers (28) of the wing cell pump (10) in the suction area are connected to the pressure outlet (69, 70) of the second hydraulic pump (40).

2. Pump arrangement according to claim 1, characterized in that the wing cell pump (10) is one with a variable displacement volume.

3. Pump arrangement according to claim 2, characterized in that the vane cell pump (10) is directly controlled with a zero stroke function when a set maximum pressure is reached.

4. Pump arrangement according to a preceding claim, characterized in that the second hydraulic pump (40) is a pump with two gear wheels (47, 64).

5 5. Pump arrangement according to claim 4, characterized in that the second hydraulic pump (40) is a filler-less internal gear pump.

6. Pump arrangement according to one of the preceding claims, characterized in that the vane cell pump (10) and the second hydraulic pump (40)

I O are combined to form a structural unit and are arranged axially one behind the other.

7. Pump arrangement according to claim 6, characterized in that axially between the rotor (22) of the vane cell pump (10) and the displacement elements.

15 th (65, 66) of the second hydraulic pump (40) a control part (49) fixed to the housing is arranged, which has a suction inlet (60) common to both hydraulic pumps (10, 40), a first pressure outlet (62) assigned to the air cell pump (10) and a second pressure output (69) assigned to the second hydraulic pump (40), a radially outer opening that is open to the rotor (22) of the wing cell pump (10).

20 suction groove (33), which is fluidly connected to the suction inlet (60) and with which the first pressure spaces (27) of the wing cell pump (10) overlap, and one open to the rotor (22) of the wing cell pump (10), radially inner suction groove (34) with which the second pressure chambers (28) of the vane cell pump (10) overlap, and a connecting channel (71)

25 has, via which the radially inner suction groove (34) is connected to the pressure outlet (69) of the second hydraulic pump (40).

8. Pump arrangement according to claim 7, characterized in that the control part (49) one to the gears (47, 64) of the second hydraulic pump (40) has open pressure groove (68) and that a straight bore extends as a connecting channel (71) between this pressure groove (68) and the inner suction groove (34).

9. Pump arrangement according to claim 7 or 8, characterized in that the connecting channel (71) is arranged such that it is directly accessible through the pressure outlet (69) of the second hydraulic pump (40).

10. Pump arrangement according to claim 7, 8 or 9, characterized in that the internal suction groove (34) is formed in a circular arc and the

Connection channel (71) at one end of the suction groove (34) opens substantially tangentially into this.

1 1. Pump arrangement according to one of claims 7 to 10, characterized in that the radially inner suction groove (34) of the wing cell pump

(10) has an area (79) of greater axial depth and an area (78) of smaller axial depth and that the connecting channel (71) opens into the area (79) of greater axial depth into the radially inner suction groove (34).

12. Pump arrangement according to claim 1 1, characterized in that the connecting channel (71) extends substantially in a radial plane perpendicular to the axes of the two pumps (10, 40).

13. Pump arrangement according to one of claims 7 to 12, characterized in that the control part (49) has a pressure groove (68) which is open towards the gears (47, 64) of the second hydraulic pump (40) and which is located radially outside two Pressure grooves (35, 36) of the air cell pump (10) is located and largely extends over an angular range in which the pressure grooves (35, 36) of the air cell pump (10) are present, and that the connecting channel (71) to radially inner suction groove (34) of the air cell pump (10) in the vicinity of one end of the pressure groove (68) of the second hydraulic pump (40) and past one end of the pressure grooves (35, 36) of the air cell pump (10) the suction groove (34) extends.

5

14. Pump arrangement according to claim 13, characterized in that the pressure grooves (35, 36) of the vane cell pump (10) are open at their other ends to a pressure channel (62) which past the pressure groove (68) of the second hydraulic pump (40) to a pressure output of the wing cell pump (10) on the

I O radial outer surface of the control part (49) leads.

15. Pump arrangement according to claim 12, 13 or 14, characterized in that the pressure grooves (35, 36) of the vane cell pump (10) and the pressure groove (68) of the second hydraulic pump (40), seen radially, overlap axially.

15

16. Pump arrangement according to one of claims 7 to 9, characterized in that the control part (49) to the gears (47, 64) of the second hydraulic pump (40) open pressure groove (68) which largely extends over an angular range , in which the pressure grooves (35, 36) of the wing housing

20 lenpumpe (10) are present that the pressure grooves (35, 36) of the wing cell pump (10) have an area (84, 85) greater axial depth and an area (82, 83) smaller axial depth and that the pressure grooves (35 , 36) and cut the pressure outlet (62) of the vane cell pump (10) in the area (84, 85) of greater axial depth of the pressure grooves (35, 36).

25

17. Pump arrangement according to one of claims 7 to 9, 16, characterized in that the control part (49) has a to the gears (47, 64) of the second hydraulic pump (40) open pressure groove (68), which largely over a Extends angular range in which the pressure grooves (35, 36) of the wing lenpump (10) are present, that the pressure groove (68) of the second hydraulic pump (40) has an area (87) of greater axial depth and an area (86) of smaller axial depth and that the pressure groove (68) and the pressure outlet (69 ) cut the second hydraulic pump (40) in the area (87) of greater axial depth of the pressure groove (68).

18. Pump arrangement according to claim 16 and 17, characterized in that the lower region (87) of the pressure groove (68) of the second hydraulic pump (40) the flatter region (82) at least the radially outer pressure groove (35) of the vane cell pump (10) axially opposite.

19. Pump arrangement according to claim 16, 17 or 18, characterized in that the lower region (84) of at least the radially outer pressure groove (35) of the vane cell pump (10) the flatter region (86) of the pressure groove (68) of the second hydraulic pump (40 ) axially opposite.

20. Pump arrangement according to one of claims 16 to 19, characterized in that the connecting channel (71) from the lower region (87) of the pressure groove (68) of the second hydraulic pump (40) over the flatter areas (82, 83) of the pressure grooves (35, 36) of the wing cell pump (10) extends to the radially inner suction groove (34) of the wing cell pump (10). •