Vane pump

A vane cell pump having an over vane pump associated with a first consumer and an under vane pump including an under vane pressure area and an under vane suction area which is connected to the over vane pump. The under vane pressure area is separated from the under vane suction area and is associated with a second consumer.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of application No. PCT/EP2010/005540, filed on 9 Sep. 2010. Priority is claimed on German Application No. 10 2009 049 532.0, filed 7 Oct. 2009, the content of which is incorporated here by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to a vane cell pump having an over vane pump associated with a first consumer and an under vane pump comprising an under vane pressure area and an under vane suction area connected to the over vane pump.

A generic vane cell pump with at least two pump portions having, respectively, a suction area and a pressure area is known from German Laid-Open Application DE 196 31 846 A1. A vehicle device known from German Laid-Open Application DE 195 14 929 A1 has a drive motor having at least two auxiliary units associated therewith, which are drivable by an individual electric motor.

SUMMARY OF THE INVENTION

In a vane cell pump having an over vane pump associated with a first consumer and an under vane pump comprising an under vane pressure area and an under vane suction area connected to the over vane pump, an object of the invention is to modify this vane cell pump such that different consumers can be supplied by the vane cell pump with hydraulic medium volume flows of different magnitudes and/or different pressures.

In one embodiment of a vane cell pump having an over vane pump associated with a first consumer and an under vane pump comprising an under vane pressure area and an under vane suction area connected to the over vane pump, the under vane pressure area is separated from the under vane suction area and is associated with a second consumer. According to an important aspect of the invention, the under vane pressure area is associated with the second consumer. As a result of the subdivision of the under vane pump carried out according to one embodiment of the invention, different volume flows at different pressure levels can be supplied simultaneously by the vane cell pump in a simple manner.

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

Another preferred embodiment of the vane cell pump is characterized in that the under vane suction area comprises at least one under vane slot portion which is associated with the first consumer via a pressure area of the over vane pump. In the pressure area of the over vane pump, a hydraulic medium is acted upon by pressure and is conveyed to the first consumer in the form of a hydraulic medium volume flow. By a connection between the under vane slot portion of the under vane suction area and the pressure area of the over vane pump, this under vane slot portion is brought to the same pressure level as the first consumer.

Another preferred embodiment of the vane cell pump is characterized in that the under vane slot portion of the under vane suction area is arranged radially inwardly and overlapping in circumferential direction in relation to a suction area of the over vane pump. By this arrangement and the connection to the pressure area of the over vane pump, it is ensured that the vanes of the vane cell pump move out reliably so as to radially outwardly contact a lift contour of the vane cell pump.

Another preferred embodiment of the vane cell pump is characterized in that the under vane pressure area comprises at least one under vane slot portion associated with the second consumer. The under vane slot portion of the under vane pressure area preferably directly communicates with the second consumer, for example, by a corresponding hydraulic line or a corresponding hydraulic channel. The under vane pressure area is supplied with hydraulic medium during operation of the vane cell pump by entraining the hydraulic medium from the under vane suction area.

Another preferred embodiment of the vane cell pump is characterized in that the under vane slot portion of the under vane pressure area is arranged radially inwardly and overlapping in circumferential direction in relation to a pressure area, or the pressure area, of the over vane pump. In the pressure area of the over vane pump, the vanes move radially inward during operation of the vane cell pump so that the hydraulic medium in the under vane slot portion of the under vane pressure area is pressurized by the inwardly moving vanes. The inward movement of the vanes in the pressure area is caused by the lift contour of the vane cell pump.

Another preferred embodiment of the vane cell pump is characterized in that the under vane suction area and the under vane pressure area each comprise two diametrically arranged under vane slot portions. The under vane slot portions of the under vane suction area are preferably each arranged radially inwardly and overlapping in circumferential direction in relation to, respectively, one of two suction areas of the vane cell pump. Similarly, the under vane slot portions of the under vane pressure area are preferably each arranged radially inwardly and overlapping in circumferential direction in relation to, respectively, one of two pressure areas of the vane cell pump.

Another preferred embodiment of the vane cell pump is characterized in that the under vane suction area and the under vane pressure area are separated from one another by a seal. The seal prevents an unintentional pressure equalization between the two under vane areas.

Another preferred embodiment of the vane cell pump is characterized in that the seal viewed from above essentially has the shape of a figure 8, the under vane suction area being arranged outside of the figure 8 and the under vane pressure area being arranged inside the figure 8. In contrast to the way in which a figure 8 is usually written, the figure 8 is so shaped in the middle that there remains an open gap providing a connection between the two under vane slot portions of the under vane pressure area.

Another preferred embodiment of the vane cell pump is characterized in that the second consumer comprises a hydraulic accumulator. The hydraulic accumulator preferably serves to store hydraulic medium which is needed, for example, in a transmission of a motor vehicle for shifting processes. The required hydraulic pressure is about 20 bar, for example. In contrast, the first consumer needs an appreciably lower pressure, e.g., 3 bar.

Another preferred embodiment of the vane cell pump is characterized in that a non-return valve is arranged between the second consumer and the under vane pressure area associated therewith. The non-return valve prevents unwanted backflow of hydraulic medium. Further, the non-return valve makes it possible to switch off the under vane pressure area associated with the second consumer as needed.

Another preferred embodiment of the vane cell pump is characterized in that the under vane pressure area can be connected to the under vane suction area by a switching valve device. The switching valve device serves to switch off the under vane pressure area. In this way, the power needed to drive the vane cell pump can be reduced. The under vane pressure area can be switched on as needed by the switching valve device for continuous charging of the hydraulic accumulator.

Another preferred embodiment of the vane cell pump is characterized in that the under vane pressure area can be connected to the first consumer by a switching valve device. This embodiment is particularly advantageous when the vane cell pump is driven electrically and has a higher starting speed than pumps driven directly by a combustion engine.

Another preferred embodiment of the vane cell pump is characterized in that the switching valve device can be actuated electromagnetically or hydraulically. By electromagnetic actuation of the switching valve device the under vane pressure area can be connected to the under vane suction area or to the first consumer whenever the pressure in the hydraulic accumulator lies above a desired minimum pressure. In so doing, the pressure in the hydraulic accumulator is acquired by a pressure sensor. When the switching valve device is actuated hydraulically, the pressure in the hydraulic accumulator can be used directly for sensing.

Another preferred embodiment of the vane cell pump is characterized in that an additional valve device is connected between the under vane suction area or the pressure area of the over vane pump and the consumer associated therewith. The valve device can be constructed as a switching valve or as a non-return valve. The additional valve device preferably serves to separate the pressure output of the over vane pump from the first consumer when the vane cell pump is stopped.

Another preferred embodiment of the vane cell pump is characterized in that the operating pressure is greater in the under vane pressure area than in the under vane suction area. This ensures that the vanes in the pressure area and in a dividing region of the over vane pump always contact the lift contour.

Another preferred embodiment of the vane cell pump is characterized in that a hydraulic resistance is connected between the under vane areas or between the under vane area and the first consumer. The hydraulic resistance is formed, for example, as a hydraulic bottleneck or as a throttle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vane cell pump1is shown schematically inFIG. 1in a highly simplified manner. The construction and operation of the vane cell pump1are described, for example, in German Laid-Open Application DE 196 31 846 A1.

Switchable double-stroke vane cell pumps can be used to meet the hydraulic demand of two different volume flows at different pressure levels at the same time in a hydraulic transmission control. In so doing, the two pump flows yielded by the double-stroke design are conveyed out of the pump separately from one another and supplied to different consumers.

It is also possible to use two or more separate pumps to supply different consumers with different volume flows and/or pressures. In German Laid-Open Application DE 195 14 929 A1, it is proposed to drive two pumps by an individual electric motor.

Hydraulic medium is supplied from a tank2to an over vane pump area4and an under vane pump area5by the vane cell pump1which is shown in a highly simplified manner inFIG. 1. The two vane pump areas4,5make up a vane pump driven by the vanes of the vane cell pump1. The pumping action of the under vane pump is achieved by a lifting movement of the radially inner ends of the vanes.

The vane cell pump1comprises the over vane pump having two substantially sickle-shaped pump chambers through which the vanes run and which are arranged in radial direction between a rotor and a lift contour. The rotor and the lift contour are defined in axial direction on one side by a pressure plate which is arranged in a housing of the vane cell pump1.

The over vane pump area4communicates with a first consumer6. The under vane pump area5communicates with a second consumer7. The second consumer7comprises a hydraulic accumulator8. The vane cell pump1is used, preferably in a motor vehicle, for supplying a transmission with hydraulic medium which is pressurized with different pressures by the vane cell pump1. The hydraulic accumulator8, for example, needs a hydraulic pressure of about 20 bar. The under vane pump area5has a displacement volume of about one cubic centimeter. The vane cell pump1is preferably driven by an electric motor.

The first consumer6is a wet clutch, for example, which needs a volume flow of up to 30 liters per minute at a pressure of 3 bar for cooling. Using the over vane pump4and under vane pump of the vane cell pump1, a volumetric flow ratio of 7 to 1 and a pressure ratio of 1 to 6 can be provided. In so doing, the two vane pump areas4and5can be operated simultaneously. Moreover, it is possible to switch off the under vane pump area5to keep the torque requirement needed for driving as low as possible at low temperatures. According to an important aspect of the invention, the under vane pump of the vane cell pump1is used with its under vane pump area5as independent pump for charging the hydraulic accumulator8.

FIGS. 2 to 8and10to11show a vane cell pump11in various embodiment examples. Identical or similar parts are provided with the same reference numbers. The vane cell pump1is connected to a tank12with hydraulic medium, particularly oil. For a better understanding of the invention, mainly a pressure plate13of the vane cell pump1is shown; this pressure plate13forms an axial contact surface for the rotor and/or the vanes of the vane cell pump1.

The pressure plate13comprises two suction areas15,16and two pressure areas17,18of the over vane pump. The pressure plate13further comprises an under vane pump with an under vane suction area which comprises two under vane slot portions21,22. The two under vane slot portions21,22are arranged radially inwardly and overlapping in circumferential direction in relation to the two suction areas15,16of the over vane pump. Hydraulic lines or hydraulic channels which connect the two under vane slot portions21,22to one of the pressure areas17,18, respectively, of the over vane pump are indicated by dashed lines. The pressure areas17,18of the over vane pump in turn communicate with a first consumer26via hydraulic lines or hydraulic channels23,24.

A second consumer27comprises a hydraulic accumulator28and communicates via hydraulic lines or hydraulic channels29,30with under vane slot portions31,32of an under vane pressure area of the under vane pump. The two under vane slot portions31,32are each arranged radially inwardly and overlapping in circumferential direction in relation to the pressure areas18,17of the over vane pump. The under vane slot portions21,22and31,32are shaped substantially as circular arcs arranged on a common circle.

The under vane slot portions21,22of the under vane suction area are filled with hydraulic medium from the under vane pump, for example, via channels or bore holes, indicated by dashed lines, in the pressure plate13. During operation of the vane cell pump1, the vanes are forcibly moved out into the suction areas15,16by the pressure in the two under vane slot portions21,22. By design, the vanes are moved into the under vane slot portions31,32through cooperation with the lift contour so that the hydraulic medium in the under vane slot portions31,32is pressurized by the inward-moving vanes. This relatively high pressure is used to fill the hydraulic accumulator28with hydraulic medium. The relatively small volume flow resulting from the small size of the under vane slot portions31,32is sufficient for this purpose. By the pressure areas17,18of the over vane pump, the first consumer26is supplied with an appreciably greater volume flow which, however, is acted upon by an appreciably lower pressure.

InFIGS. 3 and 4, the pressure plate13is shown in a top view on one side and flipped 180° in a bottom view on the other side. The separations between the under vane slot portions21,22and31,32are preferably located in angular areas of the lift contour at which no substantial change in volume of the pumping chambers or the vane cell pump11occurs.

It will be seen inFIG. 4that the two under vane slot portions31,32are arranged inside a substantially figure 8-shaped first seal35. The two under vane slot portions21,22and the pressure areas17,18of the over vane pump which extend through the pressure plate13are arranged outside the figure 8-shaped first seal35and inside a circular second seal36. The two seals35,36serve to seal against a housing of the vane cell pump11or a control plate of a transmission.

In the illustrated embodiment example, the figure 8-shaped first seal35is constructed in such a way that the two under vane slot portions31,32communicate with one another. However, by altering the first seal35in a corresponding manner or by using two circular seals, the two under vane slot portions31,32can also be sealed individually. The pressure transfer illustrated inFIG. 4has the advantage that an unwanted bending deflection of the plate due to the increased pressure in the under vane slot portions31,32on the rotor side of the pressure plate13can be compensated by the application of increased pressure on the sealing side relative to the housing or a control plate of a transmission.

Additional compensation can be achieved through the configuration, according to one embodiment of the invention, of the pressure-loaded surface and the thickness of the pressure plate13. In so doing, the gap heights should always be designed in a dimension corresponding in inverse proportion to the pressure. Drag can be minimized in this way. Because of the arrangement, according to the invention, of the two seals35,36, it is possible to integrate the vane cell pump11without housing as a plug-in component in a control plate of a transmission.

Through suitable selection of the vane geometry, the ratio of the volume flows supplied to the two consumers26,27can be varied. The pump volume of the under vane pump is given by the thickness of the vanes and the length of the vane lift By varying the vane thickness, the displacement volume of the under vane pump can be varied in a simple manner. With a given geometry of the over vane pump, doubling the vane thickness leads to an appreciable alteration in the pump delivery volume. The input power of the vane cell pump can likewise be influenced by a suitable selection of the ratio of the width of the rotor assembly to the vane lift.

In the embodiment shown inFIG. 5, a branch40is provided between the hydraulic lines29,30and the second consumer27. A non-return valve41provided between the branch40and the second consumer27prevents unwanted backflow of hydraulic medium from the hydraulic accumulator28when the vane cell pump11is stopped. Further, the non-return valve41makes it possible to switch off the under vane pump, particularly the under vane pump area with the under vane slot portions31,32which is associated with the second consumer27. This is especially helpful when the vane cell pump11is applied according to one embodiment of the invention because the charging of the hydraulic accumulator28is preferably carried out intermittently.

A hydraulic line or a hydraulic channel42leads from the branch40and is connected by additional hydraulic lines or hydraulic channels43,44to the two under vane slot portions21,22of the under vane suction area. A switching valve device45which is constructed as a 2/2 directional control valve with an open position and a blocking position is arranged in the hydraulic line42. The switching valve device45is pre-loaded in the illustrated blocking position by a spring.

In the blocking position, the connection between the under vane slot portions31,32of the second under vane pump area and the under vane slot portions21,22of the under vane suction area is interrupted so that the hydraulic accumulator8is charged via the two under vane slot portions31,32of the under vane pressure area.

By switching the switching valve device45into the open position, the connection between the under vane slot portions31,32of the under vane pressure area with the under vane slot portions21,22of the under vane suction area is released. The driving output of the vane cell pump1can be reduced when there is no need to charge the hydraulic accumulator28. Further, the connection of the two under vane pump areas by the switching valve45offers the advantage that hydraulic medium is immediately conveyed under the vanes into the suction areas15,16when starting the vane cell pump1so as to force these vanes to move out.

FIG. 6shows the vane cell pump11in which the branch40is directly connectable to the pressure output of the over vane pump and first consumer26, respectively, via a hydraulic line52or a hydraulic channel and with the intermediary of a switching valve device55. This arrangement is advantageous in electrically driven vane cell pumps11which generally have a higher starting speed than pumps that are driven directly by a combustion engine.

According to another aspect of the invention, the operating pressure in the under vane slot portions31,32of the under vane pressure area is always higher than the operating pressure in the under vane slot portions21,22of the under vane suction area. In this way, it can be ensured that the vanes in the pressure areas17,18and the dividing areas always contact the lift contour during operation. In order to achieve a sufficient difference in operating pressures required for pump operation, a throttle48;58, indicated in dashed lines, is arranged downstream of the respective switching valve device45;55in the hydraulic lines42;52of the embodiment examples shown inFIGS. 5 and 6. The throttle48;58can also be integrated in the respective switching valve device45;55.

InFIG. 7, symbol60indicates that the switching valve device55fromFIG. 6can be actuated electrically or electromagnetically. By electric or electromagnetic actuation, the switching valve55is preferably switched out of its blocking position, shown, into its open position, not shown, whenever the pressure in the hydraulic accumulator28is above a minimum pressure. To this end, the pressure in the hydraulic accumulator28is acquired by a pressure sensor.

FIG. 8shows that the switching valve45shown inFIG. 5can also be actuated hydraulically as is indicated by a control pressure line64and symbol65at the switching valve device45. The switching valve55shown inFIG. 6can be actuated hydraulically just like the switching valve45shown inFIG. 8. When actuated hydraulically as is shown inFIG. 8, the pressure in the hydraulic accumulator28is used directly for sensing.

At a lower switching point at the hydraulic accumulator28, the switching valve45is closed and the under vane pump delivers to the hydraulic accumulator28via the under vane slot portions31,32of the under vane pressure area via non-return valve41. At an upper switching point, the switching valve45is opened and the under vane pump delivers with the under vane slot portions31,32of the under vane pressure area via the under vane slot portions21,22of the under vane suction area and the pressure areas17,18with the lower operating pressure of the over vane pump.

A vane cell pump71similar to that shown inFIG. 1is illustrated in a highly simplified manner inFIG. 9. Since, in contrast to the over vane pump area4, only relatively small volume flows are supplied to the second consumer7by the under vane pump area5, the non-return valve40and the switching valve device45can both be constructed so as to be relatively small and can be integrated in the vane cell pump71in a simple manner. Further, the throttle48can be integrated in the vane cell pump71, particularly in the switching valve45. This results in a compact constructional unit which need only be connected to the tank2and the two consumers6and7by three connections.

FIGS. 10 and 11show that the output of the over vane pump can be separated from the consumer26through a switching valve device74and a non-return valve80, respectively. Accordingly, an unwanted backflow of hydraulic medium from the consumer26can be prevented. The switching valve74shown inFIG. 10is constructed as a 2/2 directional control valve which is pre-loaded in its blocking position, shown, by means of a spring. During operation of the vane cell pump11, the operating pressure of the over vane cell pump acting on the switching valve74via a control pressure line75ensures that the switching valve74opens and the connection between the vane cell pump11and the consumer26is released. The spring side of the switching valve74is connected to ambient pressure so that there are no throttle losses at the switching valve74for holding the switching valve74open.