WO2003050417A1

WO2003050417A1 - Vane-cell pump

Info

Publication number: WO2003050417A1
Application number: PCT/EP2002/013971
Authority: WO
Inventors: Johann Merz
Original assignee: Zf Lenksysteme Gmbh
Priority date: 2001-12-11
Filing date: 2002-12-10
Publication date: 2003-06-19
Also published as: DE10160787A1; EP1454061A1

Abstract

The invention relates to a vane-cell pump or a roller-cell pump for generating a stream of hydraulic fluid to a consumer, in particular power assisted steering for motor vehicles. Said pump has the following characteristics: a pump suction side (2), which can be supplied with a hydraulic fluid by a suction connection (3) and a delivery side, which can be connected to the consumer; a pump housing (1), in which a primary shaft and a pump assembly comprising a cam ring (7), a rotor (5) and vanes (6) are mounted. The pump assembly is delimited in an axial direction by pressure plates (8,9) and/or a pump cover (11) and the pump housing (1) can be sealed by the pump cover (11). The pump housing (1) and the pump cover (11) can be screwed to one another.

Description

Vane cell pump

The invention relates to a vane pump according to the preamble of claim 1.

A generic vane pump is known from EP 0 254 721 B1.

The generic vane pump for conveying a pressure medium from a container to a consumer provides a pump set that contains a cam ring in which a rotor provided with a wing is rotatably inserted. The blades are inserted in radially directed slots in the rotor and can be moved. Delivery chambers are formed between the cam ring, the rotor and the vanes and are delimited in the axial direction by control surfaces of adjacent pressure plates. A roller cell pump is also conceivable, here cylindrical rollers take over the function of the wings.

The pump package is in a pressure-filled interior inner space, which is delimited by the pump housing and a pump cover. The pump housing has a suction connection for connecting an oil tank and a pressure connection for connecting the consumer. A flow control valve for regulating the pressure medium to be returned to the pressure connection can also be provided in the pump housing.

A vane pump with a compact design is known from ÜS-A-5 098 259, in which the interior filled with pressure medium is formed by a pump housing and a pot-shaped housing cover. A structurally necessary cylindrical fit between the housing cover and the pump housing, however, leads to an expansion of the housing cover in this area. The production of the different fitting points incurs considerable manufacturing costs. Additional costs arise in the assembly of the pump housing and housing cover in that a seal between the two parts must be fitted very carefully so that it is not sheared off when the housing cover is pushed over the pump housing.

In known vane pumps, the screws with which the housing cover is attached to the pump housing often pass through the pressure-filled interior. Every single passage of the screws through the housing cover must therefore be sealed separately.

EP 0 760 907 B1 proposes an improvement for this purpose, in which it is provided that the screws for fastening the housing cover to the bearing housing are arranged outside the interior of the vane pump. The seal between the housing cover and the pump housing can thus be achieved by a simple flat seal. The arrangement of the screws known from EP 0 760 907 B1 disadvantageously increases the installation space, in particular in the radial direction.

All known vane pumps, regardless of whether they are designed as vane pumps with variable displacement volume or as vane pumps with constant displacement volume, provide a housing cover that is screwed axially with screws. As a result, the vane pump has a considerable structure, which radially enlarges the pump. The use of the screws and the seals usually required for this increase both the material costs and the manufacturing effort.

To reduce the installation space of the vane pump, the pump cover is also attached by means of a snap ring. However, this has not proven itself because the high pressures and thus the high axial forces cannot be reliably absorbed by a snap ring.

The present invention is therefore based on the object of further improving the vane pumps mentioned, in particular to provide a vane pump which has a compact design and is simple and inexpensive to produce both in terms of the material costs and also the production and assembly costs. This object is achieved according to the invention by the characterizing features of claim 1.

The fact that the pump housing and the pump cover can be screwed together means that the vane pump can have a low radial height. The previously required space for the fastening screws, four to six of which were usually required, is no longer required. The additional seals required to seal the screws can therefore also be dispensed with.

As has been shown in tests, the solution according to the invention can achieve a high axial load capacity, so that vane pumps with very high pressures can be operated reliably and permanently. By eliminating the screws and the associated sealing elements, the components required for the manufacture of the vane pump and thus the assembly effort are reduced accordingly. Since vane pumps are frequently used components, for example for operating power steering systems in the motor vehicle sector, the simple assembly with few components resulting from the solution according to the invention and therefore cost-effective production are particularly crucial.

The vane pump can be made compact and inexpensive.

As has also been found in tests, the forces which occur are advantageously distributed over a large connecting area between the pump housing and the pump cover. So be Avoided pressure peaks, which enables cost-effective production of the pump cover and possibly the pump housing. Nevertheless, high pressures can be reliably absorbed.

The pump cover, the pump housing and other required parts can have very simple shapes due to the solution according to the invention and therefore, insofar as this appears to be advantageous, can be essentially pre-cast or finish-cast using the die-casting method.

The cam ring, the necessary pressure plates and possibly the pump cover can be pinned in parts or together. Further centering is not necessary. Both the pump cover and the pump housing or a pressure plate possibly adjoining the pump cover can have flat connection surfaces. On the one hand, this enables simple manufacture, on the other hand, the seal between the pump cover and the pump housing or the pressure plate can be achieved by a simple flat seal. In this case, an O-ring can expediently also be provided in an annular groove in one of the two flat surfaces. The pressurized interior of the vane pump can, if appropriate, also be sealed thereby.

The solution according to the invention can be used for all types of vane pumps and roller cell pumps, both with a variable displacement volume and with a constant displacement volume. The design of the pump cover is not restricted by the solution according to the invention, so that it is, for example, cup-shaped, as described in EP 0 760 907 B1 ben or can be carried out according to EP 0 254 721 B1.

According to the invention it can further be provided that the pump cover is designed as a pressure plate provided with grooves and bores.

By designing the pump cover as a pressure plate, two functions are advantageously combined in one part. This results in very little construction effort.

In a constructive embodiment of the invention it can further be provided that the pump cover has a knurl or a circumferential projection on its outer circumference, and the pump housing is deformable and forms a positive connection with the knurl.

By deliberately deforming the pump housing, self-locking of the pump cover in the pump housing can advantageously be achieved. An independent loosening of the pump cover by the pressures in the interior of the vane pump is reliably prevented. It is advantageous if the pump housing has a recess or a circumferential groove for receiving the deformed part of the rim ice. A resulting collar of the pump housing can also be deformed. It is advantageous for this if the pump cover and / or the pump housing are made of aluminum. As has been found in tests, a particularly advantageous, defined deformation is possible.

Formation of the pump cover or the pump Housing with a thread with a small pitch can support self-locking if necessary.

Advantageous refinements and developments of the invention result from the further subclaims and from the exemplary embodiment described in principle below with reference to the drawing.

It shows:

1 shows a section through the vane pump according to the invention. and

Fig. 2 is an enlarged sectional view of the connection according to the invention between a pump cover and a pump housing.

Vane pumps are already well known in terms of their structure and function. Reference is made here to EP 0 254 721 B1 and EP 0 760 907 B1, which is why only the features relevant to the invention are discussed in more detail below.

Fig. 1 shows a vane pump with a pump suction side 2, which is supplied by a suction port 3 with a pressure medium. A pressure connection, not shown, is arranged in a known manner coaxially with a flow control valve described in more detail below. The vane pump is advantageously suitable for conveying a pressure medium to an auxiliary power steering system of a motor vehicle. The vane pump has in the usual way a pump package, which consists of a rotor 5, vanes 6 and a cam ring 7. The blades 6 are guided movably in known, not shown, slots of the rotor 5. Working chambers are formed in a conventional manner between the rotor 5 and the cam ring 7 and are divided into feed chambers by the vanes 6. Depending on the design of the vane pump, one or two working chambers are generally provided. However, the number of working chambers or the design of the vane pump is not relevant to the solution according to the invention. The working chambers are delimited in the axial direction by control surfaces of adjacent pressure plates 8 and 9.

The rotor 5 is mounted in a pump housing 1 via a drive shaft 10. The drive shaft 10 is supported on a pump cover 11 in the axial direction.

In alternative embodiments, it can be provided that the drive shaft 10 is mounted in the pump cover 11.

The pump housing 1 has a flow control valve 12 (bypass control) for the control or limitation of the delivery flow to the pressure outlet. The design of the flow control valve 12 (bypass control) and possibly a pressure relief valve is generally known and is therefore not described in detail. For this purpose, reference is made, for example, to US Pat. No. 5,098,259.

As can be seen from FIG. 1, the pump housing 1 and the pump cover 11 are screwed together. For this purpose, the pump cover 11 is designed as a screw cover and can be screwed into an internal thread 13 of the pump housing 1. For this purpose, the pump cover 11 is provided with an external thread 14 on its outer circumference.

In alternative embodiments, it can also be provided that the pump housing 1 is provided with an external thread and the pump cover 11 is provided with an internal thread. In experiments, however, an embodiment of the pump cover 11 with an internal thread 13 has proven to be advantageous.

The pump cover 11 borders on the cover-side pressure plate 8. The cover-side pressure plate 8 and the pump cover 11 have mutually facing flat surfaces, between which a seal 15 is arranged. The seal 15 can be designed as an O-ring. The pressurized interior of the vane pump is therefore reliably sealed. The pressure plate 8 can be designed such that, after the vane pump starts, a consumer-dependent delivery pressure is formed on the end face of the pressure plate 8 facing away from the rotor 5, which presses the pressure plate 8 against the pump package 5, 6, 7. This reduces the pump's internal gap losses to a minimum. This compensates for inevitable manufacturing tolerances and minimizes production losses. In a manner not shown, springs can also be provided which ensure mutual abutment of the pump components in the suction phase of the vane pump as long as there is still no sufficient delivery pressure. In the case shown takes over - l ü¬

the 0-ring also the spring function. In alternative embodiments, the pressurization can also be provided for both pressure plates 8, 9.

The drive shaft 10 can be held axially in the pulling direction via a locking ring, the rotor 5 and the pressure plate 9 facing away from the pump cover 11. The cover-side pressure plate 8 therefore does not have to be centered with respect to the pump cover 11. Between the pump cover 11 and the cover-side pressure plate 8, only the seal 15 is introduced, which, in addition to its already mentioned function as an elastic member between the pump cover 11 and the cover-side pressure plate 8, ensures gap compensation. In addition, the seal 15 has the task of pressing the pressure plate 8, the cam ring 7 and the pressure plate 9 on a surface 16 when the vane pump is at a standstill in order to compensate for the manufacturing tolerances.

As can be seen from the figures, the pump cover 11 is provided with a knurl 17 (or alternatively with a circumferential projection) on its outer circumference for a self-locking configuration. Due to a slight deformation of the pump cover 11 or the knurl 17, the pump cover 11 can be connected in a rotationally fixed manner to the pump housing 1. This deformation is achieved by a defined screwing of the pump cover 11 into the internal thread 13. It can be provided that the pump cover 11 is screwed in with a force of 200 to 500 N / m, preferably 300 to 400 N / m. In order to achieve a particularly advantageous rotation lock, the pump housing 1 can have a recess (not shown) or a circumferential groove exhibit. A collar can be formed through the groove. By deliberately deforming the pump cover 11 or the edge ice 17 and / or the collar or adjacent areas of the pump housing 1, an advantageous rotation lock is achieved. An independent loosening of the pump cover 11 is reliably prevented.

As can be seen from FIG. 1 and FIG. 2, the pump cover 11 has two holes 20 for screwing in, which are arranged opposite one another in the outside 21 of the pump cover 11. Of course, the pump cover 11 can also be screwed in with a different number of holes 20 or with other methods, however, as has been found in tests, the described configuration is particularly inexpensive and reliable and enables simple assembly.

The pump housing 1 has a stop 22 for limiting the screwing movement of the pump cover 11. The stop 22 ensures in a simple manner that the pump cover 11 can only be screwed into the pump housing 1 up to a certain point.

The defined stop 22 also serves to ensure that sensitive parts, in particular seals, are not damaged. The stop 22 also limits the deformation of the pump cover 11 or the pump housing 1.

The pump cover 11 can advantageously be formed from aluminum or from another known material, for example steel. A 0-ring 23 is arranged between the pump cover 11 and the pump housing 1 and is described in more detail below.

Fig. 2 shows an enlarged view of an area in which the pump cover 11 with its external thread 14 is screwed into the pump housing 1 with the internal thread 13. The pump housing 1 has a recess 24 which receives the O-ring 23. The O-ring 23 is arranged in a groove 25 of the pump cover 11 and is thus in the screwed-in state of the pump cover 11 between the groove 25 and the recess 24, as a result of which the pump cover 11 is sealed off from the pump housing 1. The recess 24 and the groove 25 ensure that the O-ring 23 is not damaged when the pump cover 11 is screwed in.

By selecting a suitable tightening torque for the pump cover 11, it is possible in one embodiment to dispense with the knurl 17.

In alternative embodiments, the pump cover 11 can also be cup-shaped, as known from EP 0 760 907 B1. The solution according to the invention shown can also be used for roller cell pumps.

Bezu <gszeichen

1 pump housing

2 pump suction side

3 Suction port 4 5 rotor

6 wings

7 curve ring

8 pressure plate

9 pressure plate

10 drive shaft

11 pump cover

12 flow control valve

13 internal thread

14 external threads

15 seal

16 area

17 knurls

18 recess

19 fret

20 holes

21 Outside of the pump cover

22 stop

23 sealing element

24 return

25 groove

Claims

claims

1. Vane pump or roller cell pump for generating a pressure medium flow to a consumer, in particular an auxiliary power steering system for motor vehicles, with the following features:

- A pump suction side which can be supplied with a pressure medium from a suction connection and a pump pressure side which can be connected to the consumer;

- A pump housing in which a drive shaft and a pump package with a cam ring, a rotor and vanes is used, the pump package being limited in the axial direction by pressure plates and / or a pump cover and the pump housing being closable by the pump cover, thereby characterizing chne t that the pump housing (1) and the pump cover (11) can be screwed together.

2. Vane pump according to claim 1, so that the pump cover (11) is designed as a screw cover and can be screwed into an internal thread (13) of the pump housing (1).

3. Vane pump according to claim 1 or 2, characterized in that the pump cover (11) is provided with an external thread (14) on its outer circumference.

4. Vane pump according to claim 1, 2 or 3, d a d u r c h g e k e n n z e i c h n e t that the pump cover (11) is designed as a pressure plate provided with grooves and holes.

5. Vane pump according to one of claims 1 to 4, since you r ch ge ke nnzeic hn et that the pump cover (11) for axially supporting the drive shaft (10) and / or the drive shaft (10) in the pump cover (11) is stored.

6. Vane pump according to one of claims 1 to 5, that the pump cover (11) is designed to be self-locking.

7. Vane pump according to one of claims 1 to 6, that the pump cover (11) is rotatably connected to the pump housing (1) by a slight deformation by a slight deformation.

8. Vane pump according to one of claims 1 to

1, characterized in that the pump cover (11) on its outer circumference Knurl (17) or a circumferential projection.

9. Vane pump according to claim 8, d a d u r c h g e k e n n z e i c h n e t that the pump housing (1) is deformable and forms a positive connection with the knurl (17).

10. Vane pump according to one of claims 1 to

9, so that the pump cover (11) can be screwed into the pump housing (1) with a force of 200 to 500 N / m, preferably 300 to 400 N / m.

11. Vane pump according to one of claims 1 to 10, dadurchge ke nn zeic hn et that the pump cover (11) has at least two holes (20) or bores, which are opposite in the front outside (21) of the pump cover (11th ) are arranged.

12. Vane pump according to one of claims 1 to

11, so that the pump housing (1) has a defined stop (22) to limit the screwing movement of the pump cover (11).

13. Vane pump according to one of claims 1 to 12, characterized in that the pump housing (1), above the internal thread (13), has a recess (24) for receiving a sealing element (23) arranged in a groove (25) of the pump cover (11).