DE102013201972A1 - DISPLACEMENT PUMP WITH VARIABLE CONVEYING VOLUME - Google Patents

Abstract

According to a first aspect of the invention, the present invention relates to a displacement pump (1) with variable displacement, in particular a single-stroke vane pump for a power steering system of a motor vehicle, comprising a housing (2) in which a driven shaft (5) and a rotor set are mounted, wherein the rotor set at least one rotor (4), characterized in that the driven shaft (5) and the rotor (4) are integrally formed with each other. Furthermore, according to a second aspect, the invention relates to a displacement pump (1) with a variable delivery volume, in particular a single-stroke vane pump for a power steering system of a motor vehicle, comprising a housing (2) in which a driven shaft (5) and a rotor set are mounted, characterized the pump (1) is designed as a throughput pump, wherein the driven shaft (5) is able to provide a drive torque, in particular for driving a further unit (28).

Description

The invention relates to a displacement pump with variable displacement according to the preamble of claim 1.

State of the art

Such positive displacement pumps (also referred to below as variable displacement pumps) are suitable, for example, for use in motor vehicles and are well known in this connection with power steering systems from the prior art. For example, the German Offenlegungsschrift discloses DE 101 28 499 A1 a positive displacement pump according to the preamble of claim 1.

The field of application of such variable displacement pumps includes, for example, a power steering device of motor vehicles. In contrast to constant-displacement pumps have variable positive displacement pumps have the advantage that the eccentricity between the rotor and the cam ring can be adjusted by a displacement of a cam ring or cam ring of the positive displacement pump within the housing. In this way, the geometric displacement of the working chambers can be increased or decreased. In this case, the term "geometric delivery volume" designates the delivered volume of the positive displacement pump per revolution. In the case of an adjustable vane pump, the geometric delivery volume is determined by the difference between the smallest and the largest cell. Due to the eccentricity between the rotor and the cam ring and / or by the rotation of the rotor, the volume of a single working chamber or work cell can be changed.

To adjust the cam ring is according to the DE 101 28 499 A1 provided that between the housing and the cam ring or between the cam ring and a so-called outer ring two mutually delimited and substantially opposite pressure chambers are formed, which can be acted upon by a fluid pressure. The cam ring is then moved in accordance with the pressure chamber acted upon by the fluid pressure accordingly, so that the geometric delivery volume can be reduced or increased. Usually, it is provided that the cam ring is moved at high speeds in a first direction, so that the geometric delivery volume is reduced, while provided at low speeds, that the cam ring is moved in an opposite direction, in which increases the geometric displacement.

The rotor set of a known from the prior art pump, such as that of DE 101 28 499 A1 , As a rule, includes a rotor, rotor blades and a cam ring and optionally a surrounding outer ring. The front side of the rotor set is sealed by planar boundary elements, which may be formed, for example, as control plates. Alternatively, however, it is also known to form a first limiting element as a control plate and a second limiting element as a bearing cap or pump cover with a plane facing the rotor set flat surface.

The rotor is usually formed as a separate element and is mounted during assembly on a shaft which supports the rotor and at the same time transmits a drive torque thereto. For this purpose, the rotor at its receiving opening for receiving the driven shaft has a toothing, which corresponds to a corresponding counter-toothing on the outer circumference of the shaft. The intermeshing teeth allow due to their positive connection, a transmission of a driving torque from the driven shaft to the rotor.

In practice, however, arise from this positive connection of rotor and shaft certain disadvantages. For example, due to a slight play between the internal teeth of the rotor and the external teeth of the shaft undesirable noise is possible. Furthermore, there may be small imbalances in the rotational movement of the rotor, which, however, can adversely affect the operation and the life of the positive displacement pump. Finally, both the shaft and the rotor are weakened by the toothing, as in the area of the teeth, especially in the tooth base local stress concentrations can occur, which can adversely affect the life.

The rotor has on its outer circumference slit-shaped receptacles for the rotor elements or wings, so that the core diameter of the rotor is further reduced. It must therefore be ensured that between the slot-shaped recess extending from the outside and the internal toothing of the rotor for sufficient material force transmission is present, so that the rotor can be used even at higher driving forces occurring.

In contrast, an object of the present invention is to reduce the disadvantages known from the prior art and to provide a variable displacement pump, which can be used in particular at higher application levels (with larger occurring pump pressures).

Another disadvantage of known positive displacement pumps is that they can be used regularly only as a solo pump, for example for a power steering. This is particularly due to the above-described problems of rotor stability, especially at higher forces acting on the system.

In contrast, another object is to provide a positive displacement pump with a more variable field of application.

To achieve the above objects, the present invention proposes according to a first aspect of the invention, a positive displacement pump having the features of claim 1. Accordingly, there is provided a positive displacement pump in which the driven shaft and the rotor are integrally formed with each other.

By an integral formation of the driven shaft and the rotor, d. H. a one-piece design of the two components separately formed in the prior art, the disadvantages associated with the necessary for a connection of the components positive connection disadvantages can be effectively avoided. In this way, it is thus possible to provide a displacement pump with variable delivery, which has a high longevity even at higher forces acting on the pumping system. An undesirable noise between the rotor and the driven shaft can also be avoided.

According to a second aspect of the present invention, it is further proposed to design the pump with the features of claim 2. Accordingly, the pump is designed as a throughput pump, wherein the driven shaft is able to provide a drive torque, in particular for driving a further unit. This present invention aspect can be combined with or used in combination with the first aspect of the invention to solve the above objects.

In a further development of the invention according to the second aspect of the invention, it can further be provided that the housing has a recess on its housing wall, by means of which the driven shaft of the positive displacement pump can be connected to a further unit. In this case, the driven shaft of the positive displacement pump can extend at least partially through the recess on the housing wall. Alternatively, however, the unit to be connected can also be introduced through the recess on the housing wall into the interior of the housing in order to be connected to the driven shaft of the positive displacement pump. In this case, a connection of the driven shaft with another unit does not necessarily mean an immediate and direct connection. Alternatively, other force-transmitting or torque-transmitting elements can be interposed.

In the event that another unit is to be driven by means of the positive displacement pump or the driven shaft of the positive displacement pump, it can be provided that the housing has a receptacle for fastening an aggregate which can be driven by the driven shaft to the housing. Such a receptacle may include, for example, mounting holes for receiving fastening screws and the like. With the aid of such a receptacle, a defined arrangement and orientation of a further unit in the displacement pump is also possible.

Regardless of the design of the pump as a throughput pump, it may be advantageous that the driven shaft is rotatably supported within the housing at least two bearing points by means of a bearing, wherein each of the bearings is preferably designed as a sliding bearing. The storage of the driven shaft as a pure sliding bearing means that a particularly low-noise bearing can be provided over known roller bearings.

Furthermore, it can be provided that the housing in the region of the bearing points of the driven shaft has a substantially groove-shaped recess, through which a fluid can be at least partially passed past the bearings. The essentially groove-shaped recess has the function of a bypass channel through which, especially in the case of increased leakage oil volume, no excessive oil flow is conducted to the shaft sealing ring of the sliding bearing. Instead, a portion of the leak can be passed over the bypass channel on the plain bearing, so that no unwanted pressure in the area of the bearing points can be built on the plain bearings.

The plain bearings may have at least one lubrication groove. Such lubrication is used in particular to ensure an oil depot in all operating conditions of the sliding bearing, which further the life of the positive displacement pump can be advantageously increased.

Regardless of the design of the positive displacement pump as a throughput pump and of the specific configuration of the bearing of the driven shaft may further be provided that the rotor set is sealed at the end by planar boundary elements, preferably a limiting element by a bearing cap (as Pump cap called) is formed, which is formed with channels for guiding a control fluid for an adjustable cam ring of the rotor set. In this way, it is possible that control oil from the valve piston area in the housing in the pressure chambers left and right of the cam ring to lead only over the bearing cap.

According to a further independent aspect, which is neither dependent on the configuration of the positive displacement pump as a throughput pump nor on the aforementioned feature, it can be provided that the housing in the region of the pressure outlet has a separately formed flow part with a defined inner diameter, for example, in the housing is pressed.

In known solutions, it is necessary to provide a defined pressure outlet in the housing by providing a defined inner diameter at this point. According to the present invention, however, the pressure outlet is predetermined by means of a separately formed flow part. In this way it is possible to provide one and the same housing for different pump variants, all of which require a different pressure outlet. Each of these housings has a uniformly dimensioned receiving area into which the separately formed flow-through part with the required inner diameter can be used in the same way as a quantity control diaphragm and thus provides the required pressure outlet for the pump variant. Thus, a cost advantage can be achieved in the manufacture of the housing by the production of a larger common part number.

According to a further independent aspect of the invention can be provided that the rotor assembly further comprises at least one outer ring, wherein the inner recess of the outer ring provides a maximum stop (also referred to as full stroke stop) and a minimum stop (also referred to as minimum stroke stop) for the adjustable cam ring and wherein the minimum stop a smaller distance from the axis of rotation of the rotor than the maximum stop.

As an alternative to this design variant, the maximum stop and the minimum stop for the adjustable cam ring can also be provided directly on the housing inner wall, wherein also the minimum stop has a smaller distance from the axis of rotation of the rotor than the maximum stop.

In known from the prior art adjustable displacement pumps a spring element is provided regularly, which is used to influence the position of the cam ring relative to the outer ring during operation of the positive displacement pump. The spring element thereby biases the cam ring from a pressure chamber and urges the cam ring in the direction of the maximum stop in order to keep the geometric delivery volume at the maximum value. When starting the pump, the spring element simultaneously assumes the function of a starting spring, d. H. the spring element ensures that the cam ring is at the start of the pump in a position in which the geometric displacement is maximum or so large that the vane pump can be started.

However, it is crucial in particular that the cam ring is not concentric with the rotor axis of rotation, so that the vane pump can be started.

In the present invention, however, the outer ring itself has a specific geometry on its inner circumference, which ensures that the cam ring can not take a concentric position to the outer ring, in which the pump could feed empty. This is provided by the fact that the maximum stop and the minimum stop are not arranged at an equal distance from the axis of rotation of the rotor. The cam ring located between the outer ring and the rotor (or between the housing wall and the rotor) consequently abuts the minimum stop before it can be brought into a concentric position with the rotor and the outer ring.

It may further be provided that the positive displacement pump has a pressure relief valve which is connected to a control of the positive displacement pump in such a way that it receives a feedback about the operating state of the pressure relief valve.

Such a pressure relief valve is provided to prevent the positive displacement pump from being damaged if the system pressure is too high. Above a certain threshold value, therefore, the pressure relief valve triggers and allows a portion of the fluid to flow into a secondary line, in order to reduce the pressure in the pump in this way. If the pressure relief valve triggers (so-called DBV operation), the control of the positive displacement pump receives feedback, for example of a hydraulic or electronic type.

In an advantageous development, it can be provided, in particular, that when the pressure relief valve triggers, the control is able to effect a displacement of the cam ring in the direction of the minimum stroke stop. In addition, this helps to reduce the system pressure within the pump.

For example, the controller can increase the fluid pressure to that pressure chamber that moves the cam ring to a position where the geometric displacement of the pump is reduced

Further advantages and aspects of the invention will be apparent to those skilled in the art from the claims and the following description of a specific embodiment. The figures, the description and the claims contain numerous features that are described in combination with each other. The expert will expediently consider these features individually and can summarize meaningful further combinations and sub-combinations.

The invention will be described in more detail below with reference to the attached figures, the figures schematically and by way of example representing a preferred embodiment of the present invention.

Show it:

1 a central longitudinal axis contained longitudinally sectioned view of a positive displacement pump according to the invention;

2 a cross-sectional view of the positive displacement pump according to 1 along the section line II-II; and

3 a longitudinal sectional view of the positive displacement pump 2 along the section line III-III.

In the figures is an embodiment of a positive displacement pump according to the invention 1 shown with variable displacement as a single-stroke vane pump. Single-stroke vane pumps are well known in terms of their basic operation from the general state of the art, for which only the example DE 199 42 466 A1 as well as the DE 102 40 499 A1 is referenced.

Below, therefore, only the features essential to the invention are shown in more detail. The illustrated vane pump 1 is designed to generate a pressure medium flow for a power steering device of a motor vehicle.

As can be seen from the figures, the vane pump 1 a housing 2 on. In the case 2 is an outer ring 3 (also referred to as intermediate ring) used. In principle, the housing 2 the vane pump 1 also the function of the outer ring 3 take. However, the formation of an outer ring has proven to be useful for mass production. In the outer ring 3 is a rotor 4 over a wave 5 stored. The rotor 4 is from a curve ring 6 surround. The curve ring 6 can be on a flattening 7 or a thickening of the outer ring 3 unroll and thus in a nearly elliptical space 8th in the outer ring 3 is formed, move.

The almost elliptical space 8th is on one side by a minimal stop 8a (also called minimum stroke stop) and on the other side by a maximum stop 8b (also called full stroke stop) limited. It should be noted that the minimum stop 8a a smaller distance from the axis of rotation R of the rotor 4 has, as the maximum stop 8b , as explained in more detail later.

The curve ring 6 is inside the room 8th between the minimum stop 8a and the maximum stop 8b adjustable or displaceable. Between the rotor 4 and the curve ring 6 are about rotor elements or wings 9 delimited working chambers 10 educated. By moving the cam ring 6 the eccentricity between the rotor changes 4 and the curve ring 6 , reducing the volume of the working chambers 10 and thus the geometric displacement of the vane pump 1 is determined.

If the rotor 4 is driven, are in slot-shaped recesses of the rotor 4 recorded wings 9 advanced and withdrawn. For this purpose, a Hinterflügelfluiddruck is used in a known manner, which substantially to the ends of the slot-shaped recesses of the rotor 4 guided wings 9 acts.

Between the outer ring 3 and the curve ring 6 are two crescent-shaped pressure chambers 11 . 12 educated. The pressure chambers 11 . 12 be at the bottom by the flattening 7 and in the upper area by a suitable sealing element 13 separated from each other and laterally by the minimum stop 8a or the maximum stop 8b limited. This allows pressurization of the two pressure chambers 11 . 12 a shift of the cam ring 6 be brought about.

The pressure chambers 11 . 12 Beyond supply bores 15 . 16 in the case 2 and corresponding holes (not shown) in the outer ring 3 fluidly connected to a control piston (not shown) or the like. This will cause the displacement of the cam ring 6 required pressure differences in the pressure chambers 11 . 12 provided. The function of a control piston as well as the control of the cam ring 6 are well known from the prior art, which is why will not be discussed in more detail below.

The housing 2 is with a suction channel 14 and a pressure channel (not shown) and a suction oil supply 17 provided to the rotor set.

The rotor set (comprising the rotor 4 , Wings 9 , the outer ring 3 as well as the curve ring 6 ) is frontally by plane boundary elements 18 . 19 sealed. This is the suction oil 17 (or the suction channel 14 ) facing the limiting element as a front plate 18 (also called control plate) formed. The limiting the rotor set on the other end face limiting element is as a bearing cap 19 (also called pump cover) formed. The bearing cap 19 in this case has a plane facing the rotor set flat surface 20 on, which ensures the frontal sealing of the rotor set.

In known manner, the fluid supply of the rear wing area through holes and slots 26a . 26b in the control panel 18 and the bearing cap 19 ensured. Like from the 1 and 3 it can be seen, however, has only that as a face plate 18 trained boundary element kidney-shaped slots 27a . 27b for controlling the fluid inlet and outlet to the working chambers 10 on. These are advantageously aligned and / or by the positioning of the control plate 18 arranged that by the operation of the vane pump 1 resulting transverse forces on the cam ring 6 essentially apply the restoring force, which presses the cam ring in the direction of maximum geometric displacement. It is possible in this way, a vane pump 1 in which completely on a spring to act on the cam ring 6 during operation of the pump 1 can be waived.

The function of the starting spring, however, is of the asymmetrically formed almost elliptical interior 8th provided the outer ring, wherein the distance between the minimum stop 8a and the rotor rotation axis R is selected such that a concentric position of the cam ring 6 to the rotor 4 by striking the rotor 4 at the minimum stop 8a is prevented.

As in the figures, especially the 1 , can be clearly seen, is the rotor 4 in contrast to the prior art in one piece or integral with the shaft 5 educated. The wave 5 (Also called rotor shaft), is on its drive side 21 using a gear 22 or a belt drive or the like driven and drives through the integral training with the rotor 4 without losses in the range of a connection to the rotor this also.

Another innovative feature of the positive displacement pump 1 is in particular in the longitudinal section of 1 and 3 shown. The pump arrangement according to the invention 1 is not formed as usual as a solo pump, but as Durchtriebspumpe, in which the housing 2 or the bearing cap 19 not only on the drive side a recess 23 has, through which the driven shaft 5 on their drive side 21 can extend, but also on the output side a corresponding recess 24 through which either the driven shaft 5 (as shown) and / or a connecting element 25 an additional aggregate 28 can extend. In the area of recesses 23 and 24 are in the usual way sealing elements 29a . 29b , For example, shaft seals, provided to ensure the tightness of the pump interior. The connecting element 25 is with the driven side portion of the driven shaft 5 such, for example via a positive connection, connected, that the driven shaft their driving torque on the connecting element 25 transfers and in this way also the aggregate 28 drives.

As another aggregate 28 In the present case, a Dieselvorförderpumpe shown by connection to the driven shaft 5 can be driven. The outer geometry of the housing 2 points in the area of the recess 24 a receiving section 30 for attachment of the further unit 28 on. This recording section 30 For example, can be provided with an external thread, a receptacle for a sealing element or the like and facilitates the attachment of another unit 28 on the vane pump according to the invention 1 ,

The wave 5 is also about two plain bearings 31a and 31b in the case 2 or in the bearing cap 19 stored. The storage as a pure plain bearing allows a particularly quiet bearing of the shaft 5 , Further, on the housing 2 or the bearing cap 19 groove-shaped recesses 32a . 32b provided, which allow it in the manner of a bypass channel, a part of the oil flow with increased leakage of oil on the plain bearings 31a . 31b passing out.

The bearing cap 19 is like in the 1 it can be seen on the housing 2 over a shoulder 33 centered, wherein in the region of the centering an additional seal, such as an annular sealing element 34 , to ensure the outer tightness of the housing 2 is provided. Using the centering of the bearing cap 19 on the housing 2 is also the alignment of the two bearings for the bearings 31a . 31b the driven shaft 5 ensured.

Furthermore, the plain bearings 31a . 31b and the associated bearings in the housing 2 or the bearing cap 24 arranged such that the Mounting geometry for the outer ring 3 centric to the bearings of the bearings 31a . 31b is arranged.

For optimum alignment of the bearing cap 19 to the face plate or control plate 18 and the outer ring 3 To ensure and secure is a pen 35 provided, which fixes the position of these elements relative to each other. It is due to the special arrangement of the pen 35 In addition, a particularly high longevity of this rigid fixation of the elements ensures each other, since this addition in the area of the minimum stop by the arrangement of connecting screws 36 is exposed to lower radial forces.

So are how to get in the 2 also recognizes the connecting screws 36 for connection of the housing 2 with the bearing cap 19 not, as known in the art, evenly over the circumference of the bearing cap 19 are arranged distributed. Instead, these are essentially in the area of the minimum stroke 8a and in the area of the flattening 7 arranged with a closer distance to each other. In this way it is possible by means of the arrangement of the connecting screws 36 to provide improved support for the internal radial forces of the pumping system and the pin 35 to relieve.

In the field of plain bearings 31a . 31b are finally provided to ensure an oil depot in all operating conditions lubrication (not shown). These are on the respective slide bearing 31a . 31b educated.

relief wells 37a and 37b each connect the bearings of the driven shaft 5 with a radial gap 38 between the rotor 4 and the curve ring 6 or with the suction channel 14 ,

LIST OF REFERENCE NUMBERS

1

displacement

2

casing

3

outer ring

4

rotor

5

wave

6

cam ring

7

flattening

8th

room

8a

minimal stop

8b

maximum stop

9

wing

10

working chamber

11

pressure chamber

12

pressure chamber

13

sealing element

14

suction

15

supply hole

16

supply hole

17

Saugölzuführung

18

faceplate

19

bearing cap

20

flat surface

21

driving side

22

gear

23

recess

24

recess

25

connecting element

26a, b

 slots

27a, b

 slots

28

aggregate

29a, b

 sealing elements

30

receiving portion

30a

sealing element

31a, b

 bearings

32a, b

 groove-shaped recesses

33

shoulder

34

annular sealing element

35

pen

36

connecting bolts

37a, b

 relief wells

38

radial gap

R

axis of rotation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10128499 A1 [0002, 0004, 0005]
• DE 19942466 A1 [0038]
• DE 10240499 A1 [0038]

Claims (12)

Positive displacement pump ( 1 ) with variable displacement, in particular one-stroke vane pump for a power steering system of a motor vehicle, comprising a housing ( 2 ), in which a driven shaft ( 5 ) and a set of rotors are mounted, wherein the set of rotors at least one rotor ( 4 ), characterized in that the driven shaft ( 5 ) and the rotor ( 4 ) are formed integrally with each other. Positive displacement pump ( 1 ) with variable displacement, in particular one-stroke vane pump for a power steering system of a motor vehicle, comprising a housing ( 2 ), in which a driven shaft ( 5 ) and a set of rotors are mounted, characterized in that the pump ( 1 ) is formed as Durchtriebspumpe, wherein the driven shaft ( 5 ) a drive torque, in particular for driving a further unit ( 28 ). Positive displacement pump ( 1 ) according to claim 2, characterized in that the housing ( 2 ) a recess ( 25 ) on its housing wall, through which the driven shaft ( 5 ) of the positive displacement pump ( 1 ) with another aggregate ( 28 ) can be connected. Positive displacement pump ( 1 ) according to one of claims 1 to 3, characterized in that the driven shaft ( 5 ) within the housing ( 2 ) is rotatably supported at least two bearing points by means of a bearing, each of the bearings preferably as a sliding bearing ( 31a . 31b ) is trained. Positive displacement pump ( 1 ) according to claim 4, characterized in that the housing ( 2 ) in the region of the bearing points of the driven shaft a substantially groove-shaped recess ( 32a . 32b ), through which a fluid at least partially at the bearings ( 31a . 31b ) can be passed. Positive displacement pump according to claim 4 or 5, characterized in that the slide bearings have at least one lubrication groove. Positive displacement pump ( 1 ) according to one of the preceding claims, characterized in that the set of rotors is sealed off at the end by plane limiting elements, wherein a limiting element by a bearing plate ( 19 formed with channels for guiding a control fluid for an adjustable cam ring ( 6 ) of the rotor set is formed. Positive displacement pump ( 1 ) according to one of claims 2 to 6, characterized in that the housing ( 2 ) a receiving section ( 30 ) for fixing one of the driven shaft ( 5 ) drivable aggregate ( 28 ) on the housing ( 2 ) having. Positive displacement pump according to one of the preceding claims, characterized in that the housing in the region of the pressure outlet has a separately formed flow part with a defined inner diameter, which is for example pressed into the housing. Positive displacement pump ( 1 ) according to any one of the preceding claims, characterized in that the rotor set further comprises at least one outer ring ( 3 ), wherein the inner recess of the outer ring ( 3 ) a maximum stop ( 8b ) as well as a minimal stop ( 8a ) for the adjustable cam ring ( 6 ) and where the minimum stop ( 8a ) a smaller distance to the axis of rotation (R) of the rotor ( 4 ) than the maximum stop ( 8b ). Positive displacement pump according to one of the preceding claims, characterized in that the positive displacement pump has a pressure relief valve which is connected to a control of the positive displacement pump in such a way that it receives a feedback about the operating state of the pressure relief valve. Positive displacement pump according to claim 10, characterized in that when the pressure limiting valve triggers, the controller is able to effect a displacement of the cam ring in the direction of minimum stroke.

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