EP2486280B1 - Vane pump - Google Patents

Description

The invention relates to a vane pump having a wing pump associated with a first consumer and an under wing pump including an under wing pressure area and a lower wing suction area connected to the wing pump.

From the German patent application DE 196 31 846 A1 is a generic vane pump with at least two each having a suction region and a pressure region having pump sections known. From the German patent application DE 195 14 929 A1 is a vehicle device with a drive motor known to which at least two ancillaries are assigned, which are driven by a single electric motor. The international publication WO 03/056180 A1 discloses a vane pump that can supply multiple consumers, but without using the underfloor pressure ranges as a supply to a separate consumer. The German patent application DE 39 13 414 A1 discloses a multi-circuit control pump for pressure medium supply of several in the pressure level and demand quantity of different supply circuits.

The object of the invention is to change a vane pump with a wing pump, which is associated with a first consumer, and an underfloor pump, which includes an underfloor pressure region and a lower wing suction, which is connected to the wing pump to change so that with the vane pump different consumers with hydraulic medium volume flows can be supplied, which are different in size and / or have different pressures.

The object is solved in a vane pump with a wing pump associated with a first consumer and an underfloor pump including an underfloor pressure area and a lower wing suction area connected to the wing pump, wherein the underfloor pressure area is separated from the lower wing suction area and a second consumer According to one essential aspect of the invention, the underfloor pressure range is assigned to the second consumer. Due to the subdivision of the underfloor pump according to the invention can with the vane pump to simple Way different volume flows are provided at different pressure levels at the same time.

A preferred embodiment of the vane pump is characterized in that the lower wing suction and the lower wing pressure range can be acted upon with different pressures. This makes it possible for the vane pump to simultaneously provide different pressure levels for different consumers. The lower wing suction area and the lower wing pressure area are also referred to as under wing areas.

Another preferred exemplary embodiment of the vane pump is characterized in that the lower wing suction region comprises at least one lower wing groove section which is assigned to the first consumer via a pressure region of the wing pump. In the pressure range of the wing pump, hydraulic medium is pressurized and conveyed in the form of a hydraulic medium volume flow to the first consumer. Through a connection between the lower wing groove portion of the lower wing suction area and the pressure area of the upper wing pump, this lower wing groove portion is brought to the same pressure level as the first consumer.

A further preferred exemplary embodiment of the vane pump is characterized in that the lower vane groove portion of the lower vane suction region is arranged radially inside and in the circumferential direction overlapping to a suction region of the vane pump. By this arrangement and the connection with the pressure range of the wing pump ensures that the wings of the vane pump safely extend, so that they rest radially outward on a stroke contour of the vane pump.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that the lower-wing pressure region comprises at least one lower-wing groove section which is assigned to the second consumer. The underfloor groove portion of the underfoil pressure range is preferably directly, for example via a corresponding hydraulic line or a corresponding hydraulic channel, with the second consumer in combination. The underfoil pressure range is supplied during operation of the vane pump by entrainment of the hydraulic medium from the lower wing suction with hydraulic medium.

A further preferred exemplary embodiment of the vane pump is characterized in that the lower vane groove portion of the lower vane pressure region is arranged radially inside and in the circumferential direction overlapping one or the pressure region of the upper vane pump. In the pressure range of the wing pump, the vanes move radially inwardly during operation of the vane pump, thereby pressurizing the hydraulic medium in the underfloor groove portion of the underfloor pressure area by the incoming vanes. The retraction of the wings in the pressure range is effected by the stroke contour of the vane pump.

Another preferred exemplary embodiment of the vane pump is characterized in that the lower wing suction region and the lower wing pressure region each comprise two diametrically arranged lower blade groove sections. The lower-wing groove portions of the lower-wing suction region are preferably arranged radially inward and circumferentially overlapping each with one of two suction regions of the vane-cell pump. Analogously, the underfloor groove sections of the underfoil pressure region are preferably arranged radially in each case and overlapping in the circumferential direction in each case to one of two pressure regions of the vane pump.

Another preferred embodiment of the vane pump is characterized in that the lower wing suction and the lower wing pressure range are separated by a seal. The seal prevents unwanted pressure equalization between the two lower wing areas.

A further preferred embodiment of the vane pump is characterized in that the seal has in plan view substantially the shape of a figure eight, outside which the lower wing suction area and within which the lower wing pressure area is arranged. In this case, unlike the usual notation, the figure 8 is designed at its center so as to leave free a distance which establishes a connection between the two underfloor groove portions of the underfoil printing area.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that a check valve is arranged between the second consumer and the lower-wing pressure region assigned to it. The check valve on the one hand prevents unwanted backflow of hydraulic medium. In addition, the check valve allows a demand-dependent switching off of the second consumer associated Unterflügeldruckbereichs.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that the underfloor pressure region can be connected to the lower-wing suction region via a switching valve device. The switching valve device serves to shut off the underfloor pressure range. As a result, the power required to drive the vane pump can be reduced. For a discontinuous charging of the hydraulic accumulator, the underfloor pressure range can be switched on with the aid of the switching valve device as needed.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that the underfloor pressure region can be connected to the first consumer via a switching valve device. This embodiment is particularly advantageous when the vane pump is electrically driven and has a higher starting speed than pumps driven directly by an internal combustion engine.

A further preferred embodiment of the vane pump is characterized in that the switching valve device is electromagnetically or hydraulically actuated. For example, via the electromagnetic actuation of the switching valve device, the underfoil pressure range can be connected to the lower-wing suction region or to the first consumer when the pressure in the hydraulic accumulator is above a desired minimum pressure. In this case, the pressure in the hydraulic accumulator is detected, for example, by means of a pressure sensor. In the hydraulic actuation of the switching valve device, the pressure in the hydraulic accumulator can be used directly for sensing.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that an additional valve device is connected between the lower-wing suction region or the pressure region of the upper-wing pump and the consumer associated therewith. The valve device can be designed as a switching valve or as a check valve. The additional valve device is preferably used to separate the pressure output of the wing pump at standstill of the vane pump from the first consumer.

A further preferred embodiment of the vane pump is characterized in that the operating pressure in the lower wing pressure range is greater than in the lower wing suction. This ensures that the wings always rest against the stroke contour in the pressure area and in a separation area of the wing pump.

A further preferred exemplary embodiment of the vane-cell pump is characterized in that a hydraulic resistance is connected between the lower-wing regions or between the lower-wing pressure region and the first consumer. The hydraulic resistance is designed, for example, as a hydraulic bottleneck or as a throttle.

Figur 1

eine stark vereinfachte Darstellung einer erfindungsgemäßen Flügelzellenpumpe;

Figur 2

ein Ausführungsbeispiel der erfindungsgemäßen Flügelzellenpumpe, die zwei unterschiedliche Verbraucher mit unterschiedlichen Hydraulikmediumvolumenströmen versorgt, die unterschiedliche Drücke aufweisen;

Figur 3

eine Druckplatte der Flügelzellenpumpe aus Figur 2 in der Draufsicht;

Figur 4

die Druckplatte aus Figur 3 in der Untersicht;

Figur 5

ein ähnliches Ausführungsbeispiel wie in Figur 2 mit einer möglichen Verbindung zwischen verschiedenen Unterflügelbereichen;

Figur 6

ein ähnliches Ausführungsbeispiel wie in Figur 2 mit einer möglichen Verbindung zwischen einem der Unterflügelbereiche und einem diesem nicht zugeordneten Verbraucher;

Figur 7

eine Variante eines Schaltventils aus Figur 6;

Figur 8

ein ähnliches Ausführungsbeispiel wie in Figur 5 mit einem anderen Schaltventil;

Figur 9

eine ähnliche Darstellung wie in Figur 1 mit in die Flügelzellenpumpe integrierten Ventilen;

Figur 10

ein ähnliches Ausführungsbeispiel wie in Figur 6 mit einer zusätzlichen Schaltventileinrichtung und

Figur 11

ein ähnliches Ausführungsbeispiel wie in Figur 10 mit einem Rückschlagventil.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail. Show it:

FIG. 1

a greatly simplified representation of a vane pump according to the invention;

FIG. 2

an embodiment of the vane pump according to the invention, which supplies two different consumers with different hydraulic medium flow rates having different pressures;

FIG. 3

a pressure plate of the vane pump FIG. 2 in the plan view;

FIG. 4

the pressure plate off FIG. 3 in the lower view;

FIG. 5

a similar embodiment as in FIG. 2 with a possible connection between different sub-wing areas;

FIG. 6

a similar embodiment as in FIG. 2 with a possible connection between one of the underflying areas and a consumer not assigned to it;

FIG. 7

a variant of a switching valve FIG. 6 ;

FIG. 8

a similar embodiment as in FIG. 5 with another switching valve;

FIG. 9

a similar representation as in FIG. 1 with valves integrated into the vane pump;

FIG. 10

a similar embodiment as in FIG. 6 with an additional switching valve device and

FIG. 11

a similar embodiment as in FIG. 10 with a check valve.

In FIG. 1 is a vane pump 1 very simplified schematically shown. The structure and function of the vane pump 1 are, for example, in the German Offenlegungsschrift DE 196 31 846 A1 described.

In order to cover the hydraulic demand of two different volume flows at different pressure levels, for example in a hydraulic transmission control, at the same time, switchable double-stroke vane pumps can be used. Here, the two pump floods resulting from the Doppelhubigkeit, separately conveyed from the pump and fed to different consumers.

It is also possible to use two or more separate pumps to supply different consumers with different flow rates and / or pressures. In the German patent application DE 195 14 929 A1 It is proposed to drive two pumps by a single electric motor.

By the in FIG. 1 The vane pump 1, which is shown in a highly simplified manner, is supplied with hydraulic fluid from a tank 2 to a vane pump area 4 and an underwing pump area 5. The two vane pump areas 4, 5 represent a vane pump, which is operated by vanes of the vane pump 1. The conveying effect of the underfloor pump is achieved by a lifting movement of the radially inner wing ends.

The vane pump 1 comprises the wing pump with two substantially crescent-shaped delivery spaces, which are traversed by the wings and are arranged in the radial direction between a rotor and a stroke contour. The rotor and the stroke contour are limited in the axial direction on one side by a pressure plate, which is arranged for example in a housing of the vane pump 1.

The upper wing pump region 4 is connected to a first consumer 6 in connection. The underwing pump area 5 communicates with a second consumer 7. The second consumer 7 comprises a hydraulic accumulator 8. The vane pump 1 is, preferably in a motor vehicle, used to supply a transmission with hydraulic medium, which can be acted upon by the vane pump 1 with different pressures. The hydraulic accumulator 8 requires, for example, a hydraulic pressure of about 20 bar. The underwing pump area 5 has a stroke volume of approximately one cubic centimeter. The vane pump 1 is preferably driven by an electric motor.

The first consumer 6 is, for example, a wet clutch which requires a volume flow of up to 30 liters per minute for cooling at a pressure of 3 bar. By utilizing the underfloor pump and the underfloor pump of the vane pump 1, a volumetric flow ratio of 7 to 1 and a pressure ratio of 1 to 6 can be provided. The two vane pump areas 4 and 5 can be operated simultaneously. Moreover, it is possible to switch off the underfloor pump area 5 in order to keep the torque requirement required for the drive as low as possible at low temperatures. According to an essential aspect of the invention, the underfloor pump the vane pump 1 is used with its underwing pump area 5 as an independent pump to charge the hydraulic accumulator 8.

In the FIGS. 2 to 8 and 10 to 11 a vane pump 11 is shown in various embodiments. The same or similar parts are provided with the same reference numerals. The vane pump 11 is connected to a tank 12 with hydraulic medium, in particular oil. For a better understanding of the invention of the vane pump 11 mainly a pressure plate 13 is shown, which represents an axial bearing surface for the rotor and / or the blades of the vane pump 1.

The pressure plate 13 comprises two suction regions 15, 16 and two pressure regions 17, 18 of the overflow pump. The pressure plate 13 further comprises one of the underfloor pump with a lower wing suction region, which comprises two Unterflügelnutabschnitte 21, 22. The two Unterflügelnutabschnitte 21, 22 are arranged radially inwardly and circumferentially overlapping the two suction regions 15, 16 of the wing pump. By dashed lines hydraulic lines or hydraulic channels are indicated, via which the two Unterflügelnutabschnitte 21, 22 are each connected to one of the pressure areas 17, 18 of the wing pump. The pressure areas 17, 18 of the wing pump in turn are connected via hydraulic lines or hydraulic channels 23, 24 with a first consumer 26 in connection.

A second load 27 comprises a hydraulic accumulator 28 and is connected via hydraulic lines or hydraulic channels 29, 30 with Unterflügelnutabschnitten 31, 32 of an underfloor pressure range of the underfloor pump in connection. The two Unterflügelnutabschnitte 31, 32 are each disposed radially inwardly and circumferentially overlapping the pressure areas 18, 17 of the wing pump. The Unterflügelnutabschnitte 21, 22 and 31, 32 have substantially the shape of circular arcs, which are arranged on a common circle.

The Unterflügelnutabschnitte 21, 22 of the lower wing suction are filled, for example, indicated by dashed lines channels or holes in the pressure plate 13 from the wing pump with hydraulic medium. In operation of the vane pump 1, the wings are forcibly extended by the pressure in the two Unterflügelnutabschnitten 21, 22 in the suction regions 15, 16. In the Unterflügelnutabschnitten 31, 32, the wings are by design retracted by the interaction with the stroke contour, so that the hydraulic medium in the Unterflügelnutabschnitten 31, 32 is acted upon by the retracting wing with pressure. This relatively high pressure is used to fill the hydraulic accumulator 28 with hydraulic medium. The by the small size of the Unterflügelnutabschnitte 31, 32 relatively small volume flow is sufficient for this purpose. The first consumer 26 is supplied via the pressure regions 17, 18 of the wing pump with a significantly larger volume flow, which is, however, subjected to a significantly lower pressure.

In the FIGS. 3 and 4 the pressure plate 13 is shown in plan view on one side and folded 180 degrees in the bottom view on the other side. The separation points between the Unterflügelnutabschnitten 21, 22 and 31, 32 are preferably in angular ranges of the stroke contour, where no significant change in volume of the delivery chambers of the vane pump 11 occurs.

In FIG. 4 it can be seen that the two Unterflügelnutabschnitte 31, 32 are disposed within a substantially eight-shaped first seal 35. The two Unterflügelnutabschnitte 21, 22 and extending through the pressure plate 13 through pressure regions 17, 18 of the wing pump are arranged outside of the eight-shaped first seal 35 and within a circular second seal 36. The two seals 35, 36 serve to seal against a housing of the vane pump 11 or a control plate of a transmission.

The eight-shaped first seal 35 is designed in the illustrated embodiment so that the two Unterflügelnutabschnitte 31, 32 communicate with each other. By appropriate modification of the first seal 35 or by using two circular seals, the two Unterflügelnutabschnitte 31, 32 but also be sealed individually. In the FIG. 4 illustrated pressure transfer has the advantage that an undesirable plate deflection can be compensated by the increased pressures in the Unterflügelnutabschnitten 31, 32 on the rotor side of the pressure plate 13 by the pressurization with the increased pressure on the sealing side to the housing or to a control plate of a transmission.

The inventive design of the pressurized surfaces and the thickness of the pressure plate 13, an additional compensation can be achieved. The gap heights should always be designed in a measure that is inversely proportional to the pressure. As a result, the towing capacity can be minimized. The inventive arrangement of the two seals 35, 36, it is possible to integrate the vane pump 11 without housing as a plug-in component in a control plate of a transmission.

By a suitable choice of the blade geometry, the ratio of the two consumers 26, 27 supplied volume flows can be varied. The pump volume of the underfloor pump results from the thickness of the wings and the length of the wing stroke. By varying the wing thickness, the stroke volume of the underfloor pump can be varied in a simple manner. With a given geometry of the wing pump doubling the wing thickness leads to a significant change in the pump delivery volume. By a suitable choice of the ratio of the width of the rotor group to the wing stroke, the input power of the vane pump can also be influenced.

At the in FIG. 5 illustrated embodiment, a branch 40 is provided between the hydraulic lines 29, 30 and the second load 27. Between the branch 40 and the second consumer 27, a check valve 41 is provided which prevents unwanted backflow of hydraulic fluid from the hydraulic accumulator 28 when the vane pump 11 is stationary. By the check valve 41 is further made possible that the underfloor pump, in particular the second consumer 27 associated underfloor pump area with the Unterflügelnutabschnitten 31, 32, can be switched off. This is particularly useful in the application of the vane pump 11 according to the invention, since the charging of the hydraulic accumulator 28 is preferably carried out discontinuously.

From the branch 40 is a hydraulic line or a hydraulic channel 42 goes out, which is connected via further hydraulic lines or hydraulic channels 43, 44 with the two Unterflügelnutabschnitten 21, 22 of the lower wing suction. In the hydraulic line 42, a switching valve device 45 is arranged, which is designed as a 2/2-way valve with an open position and a blocking position. By a spring, the switching valve device 45 is biased in the illustrated blocking position.

In the locked position, communication between the under-wing groove portions 31, 32 of the second under-wing pump portion and the lower-wing groove portions 21, 22 of the lower-wing suction portion is interrupted, so that the hydraulic accumulator 8 is charged via the two under-wing groove portions 31, 32 of the under-wing pressure portion.

By switching the switching valve means 45 to the open position, the communication between the under-wing groove portions 31, 32 of the under-wing pressure portion with the under-wing groove portions 21, 22 of the lower-wing suction portion is released. Thereby, the driving power of the vane pump 1 can be reduced when there is no need to charge the hydraulic accumulator 28. The connection of the two sub-vane pump areas via the switching valve 45 also provides the advantage that when starting the vane pump 1 immediately hydraulic medium under the wings in the suction areas 15, 16 is promoted to force an extension of these wings.

In FIG. 6 an embodiment of the vane pump 11 is shown, in which the branch 40 via a hydraulic line 52 or a hydraulic channel and with the interposition of a switching valve device 55 directly to the pressure output of the wing pump or the first load 26 is connectable. This arrangement is advantageous in electrically driven vane pumps 11, which typically have a higher starting speed than pumps driven directly by an internal combustion engine.

According to another aspect of the invention, the operating pressure in the underfloor groove portions 31, 32 of the underfloor pressure region is always above the operating pressure in the underfloor groove portions 21, 22 of the lower wing suction region. This can ensure that the wings in the pressure areas 17, 18 and the separation areas in operation always rest against the stroke contour. In order to achieve a necessary difference in the operating pressures necessary for pump operation, in the hydraulic lines 42; 52 of the in the Figures 5 and 6 illustrated embodiments each dashed a throttle 48; 58 indicated that the respective switching valve device 45; 55 is connected downstream. The throttle 48; 58 can also in the respective switching valve device 45; 55 be integrated.

In FIG. 7 is indicated by a symbol 60 that the switching valve device 55 from FIG. 6 can be electrically or electromagnetically actuated. By the electrical respectively electromagnetic actuation, the switching valve 55 is preferably always switched from its illustrated blocking position to its open position, not shown, when the pressure in the hydraulic accumulator 28 is above a minimum pressure. For this purpose, the pressure in the hydraulic accumulator 28 is detected by means of a pressure sensor.

In FIG. 8 is hinted that in FIG. 5 shown switching valve 45 may also be hydraulically actuated, as indicated by a control pressure line 64 and a symbol 65 on the switching valve device 45. This in FIG. 6 shown switching valve 55, as well as the switching valve 45 in FIG. 8 , hydraulically operated. At the in FIG. 8 shown hydraulic actuation of the pressure in the hydraulic accumulator 28 is used directly for sensing.

At a lower switching point on the hydraulic accumulator 28, the switching valve 45 is closed and the underfloor pump conveys via the Unterflügelnutabschnitte 31, 32 of the Unterflügeldruckbereichs via the check valve 41 in the hydraulic accumulator 28. At an upper switching point, the switching valve 45 is opened and the underfloor pump promotes the Unterflügelnutabschnitten 31st , 32 lower wing pressure range over the Unterflügelnutabschnitte 21, 22 of the lower wing suction and the pressure areas 17, 18 with the lower operating pressure of the wing pump.

In FIG. 9 is a similar vane pump 71 as in FIG. 1 shown greatly simplified. Since only relatively small volume flows are supplied to the second consumer 7 with the lower pad pump region 5, in contrast to the upper pad pump region 4, both the check valve 40 and the switching valve device 45 can be made relatively small and integrated into the vane pump 71 in a simple manner. In addition, the throttle 48 in the vane pump 71, in particular in the switching valve 45, are integrated. This results in a compact unit that only needs to be connected with three connections to the tank 2 and the two consumers 6 and 7.

In the Figures 10 and 11 It is shown that the output of the wing pump can be separated by a switching valve device 74 and a check valve 80 from the consumer 26. As a result, an undesired backflow of hydraulic medium from the consumer 26 can be avoided. This in FIG. 10 illustrated switching valve 74 is designed as a 2/2-way valve, which by means of a spring in its illustrated blocking position is biased. During operation of the vane pump 11, the operating pressure of the vane cell pump acting on the switching valve 74 via a control pressure line 75 ensures that the switching valve 74 opens and releases the connection between the vane pump 11 and the consumer 26. The spring side of the switching valve 74 is connected to ambient pressure, so that at the switching valve 74 no throttle losses for keeping the switching valve 74 open.

LIST OF REFERENCE NUMBERS

1

Vane pump

2

tank

4

Upper wing pump area

5

Underwing pump area

6

first consumer

7

second consumer

8th

hydraulic accumulator

11

Vane pump

12

tank

13

printing plate

15

suction area

16

suction area

17

pressure range

18

pressure range

21

Unterflügelnutabschnitt

22

Unterflügelnutabschnitt

23

hydraulic line

24

hydraulic line

26

first consumer

27

second consumer

28

hydraulic accumulator

29

hydraulic line

30

hydraulic line

31

Unterflügelnutabschnitt

32

Unterflügelnutabschnitt

35

first seal

36

second seal

40

branch

41

check valve

42

hydraulic line

43

hydraulic line

44

hydraulic line

45

Valving means

48

throttle

52

hydraulic line

55

Valving means

58

throttle

60

symbol

64

control line

65

symbol

71

Vane pump

74

additional switching valve device

75

control line

80

check valve

Claims (16)

1. Vane pump with an upper vane pump assigned to a first consumer (6; 26) and a lower vane pump comprising a lower vane pressure area and a lower vane suction area which is connected to the upper vane pump, characterised in that the lower vane pressure area is separated from the lower vane suction area and is assigned to a second consumer (7; 27).
2. Vane pump according to claim 1, characterised in that the sub-divided lower vane areas can be subjected to different pressures.
3. Vane pump according to one of the preceding claims, characterised in that the lower vane suction area comprises at least one lower vane groove section (21, 22) which is assigned via a pressure area (17, 18) of the upper vane pump to the first consumer (6; 26).
4. Vane pump according to claim 3, characterised in that the lower vane groove section (21, 22) of the lower vane suction area is arranged radially within and overlapping in the circumferential direction with respect to a suction area (15, 16) of the upper vane pump.
5. Vane pump according to claim 3 or 4, characterised in that the lower vane pressure area comprises at least one lower vane groove section (31, 32) which is assigned to the second consumer (7; 27).
6. Vane pump according to claim 5, characterised in that the lower vane groove section (31, 32) of the lower vane pressure area is arranged radially within and overlapping in the circumferential direction with respect to the pressure area (17, 18) of the upper vane pump.
7. Vane pump according to claim 5 or 6, characterised in that the lower vane suction area and the lower vane pressure area each have two diametrically arranged lower vane groove sections (21, 22; 31, 32).
8. Vane pump according to one of the preceding claims, characterised in that the lower vane suction area and the lower vane pressure area are separated from each other by a seal (35).
9. Vane pump according to claim 8, characterised in that the seal (35) has in the top view essentially the form of a figure eight, outside of which the lower vane suction area and within which the lower vane pressure area are arranged.
10. Vane pump according to one of the preceding claims, characterised in that a non-return valve (41) is arranged between the second consumer (7; 27) and the lower vane pressure area assigned thereto.
11. Vane pump according to one of the preceding claims, characterised in that the lower vane pressure area can be connected via a switching valve means (45) to the lower vane suction area.
12. Vane pump according to one of the claims 1 to 10, characterised in that the lower vane pressure area can be connected via a switching valve means (55) to the first consumer (6; 26).
13. Vane pump according to claim 11 or 12, characterised in that the switching valve means (45; 55) can be electro-magnetically or hydraulically activated.
14. Vane pump according to one of the preceding claims, characterised in that an additional valve means (74) is provided between the lower vane suction area or the pressure area (17, 18) of the upper vane pump and the consumer (6; 26) assigned thereto.
15. Vane pump according to one of the preceding claims, characterised in that the operating pressure in the lower vane pressure area is greater than in the lower vane suction area.
16. Vane pump according to one of the preceding claims, characterised in that a hydraulic resistor (48; 58) is provided between the lower vane areas or between the lower vane pressure area and the first consumer (6; 26).

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