DE29521260U1 - pump - Google Patents

Description

Gieiss &iacgr;

Patent Attorney's Office

Df.jur. Dipl.-Ing. A.-O. Gieiss * Stuttgart 70469 STUTTGART

Dipl.-Ing. Rainer Große* Stuttgart MAYBACHSTRASSE6A

Dr. rer. nat. Dipi.-Chem. Phone: (0711)8145 55

J.-Detlev Frhr. v. Uexküll * Hamburg Fax: (0711) 8130 32

Dip!-1ng. Henry Schneider * Berün Telex: 72 27 72 jura d

Oipl.-!ng. Michael Lindner Stuttgart Telegrams: JURAPAT

Patent Attorneys 22609 HAMBURG

* European Patent Attorneys KONIGGRÄTZSTRASSE 8

Phone: (040) 80 33 97

(040) 80 10 66

Fax: (040) 80 52 47

10247 BERLIN

GUERTELSTRASSE 30
Telephone: (030)2 94 13 35 Fax: (030) 2941337 Telegrams: JURAPAT

Utility model application

pump

LuK

Vehicle Hydraulics GmbH & Co. KG
Zeppelinstrasse 3

61352 BAD-HOMBURG

13 087 C.l.-Iio

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Track & Large

Patent Attorney's Office
StuttgartBerlinHamburg

Description

The invention relates to pumps, namely roller cell pumps, vane cell pumps and gear pumps according to the preamble of claims 1 and 7.

The problem with pumps of the type discussed here is that a negative pressure can develop in the suction area, which leads to cavitation, which on the one hand leads to a lot of noise and on the other hand can cause damage.

It is therefore an object of the invention to create a pump which does not have these disadvantages.

To solve this problem, a pump is proposed which has the features mentioned in claims 1 and 7. Cavitation effects can be reliably avoided by charging the suction area of the pumps with pressurized fluid returned from a consumer, i.e. by supplying the suction area with a fluid under excess pressure.

An embodiment of the invention is preferred, in which the returned by the consumer

12 087GL-IiO

13 September 1995

Fluid is fed into a pressure chamber that has an outlet opening into the suction chamber of the pump. The cross-section of this outlet is smaller than that of the channel that supplies the fluid. This design accelerates the supplied fluid as it passes through the outlet. The fluid that enters the suction chamber at high speed can therefore entrain a fluid that is present there and supply it to the suction area of the pump.

A preferred embodiment of the pump is one in which the cross-section of the suction chamber is larger than that of the outlet. Through hydraulic energy conversion, the fluid exiting the outlet at high speed builds up a charging pressure in the suction chamber, which helps to prevent cavitation in the suction area of the pump.

Finally, a preferred embodiment of the pump is one in which a wall section is provided that separates the suction area of the pump from the suction connection. This wall area can, on the one hand, influence the flow from the suction connection into the suction area, for example, to accelerate the flow of fluid passing through, and on the other hand, it can prevent the pump chamber from running dry when the pump is at a standstill, so that the pump starts up better.

Further details emerge from the remaining subclaims.

The invention is explained in more detail below with reference to the drawing.

Figure 1 A plan view of a first embodiment of an opened vane pump and

Figure 2 is a plan view of a second embodiment of an opened vane pump.

The invention relates to gear pumps, roller cell pumps and vane cell pumps. A vane cell pump is described below purely as an example. However, it should be noted that the charging of the suction area of the vane cell pump described here can also be used with roller cell and gear pumps.

The vane pump 1 shown in Figure 1 has a rotor 3, in the peripheral wall of which radially extending slots 5 are introduced, which accommodate radially movable vanes 7.

The rotor 3 is rotatably arranged in a contour ring 9, the inner surface 11 of which is designed in such a way that two opposite, identically designed conveying chambers 13 and 15 are formed, which are essentially sickle-shaped. When the rotor 3 rotates inside the contour ring 9, the blades move into the slots and

-A-

so that suction and pressure areas are formed in the conveying chambers 13 and 15. When the rotor 3 rotates, two opposing suction areas 17 and 19 and two opposing pressure areas 21 and 23 are created, the arrangement of which is shown in Figure 1 when the rotor rotates anti-clockwise.

The contour ring 9 is inserted into a pump housing 25, inside which a suction connection 27 opens. A connection is connected to the suction connection 27, which leads to a tank into which fluid returned by the consumer, which is under a low pressure at most, is introduced. The suction connection is connected to a suction chamber 29 which practically completely surrounds the contour ring 9 and which is in fluid communication with the suction areas 17 and 19 of the pump. The suction chamber 29 is closed off at its end facing away from the suction connection 27 by a sealing bead 31. Beyond the sealing bead there is a pressure chamber 33 which is delimited on the one hand by the housing 25 and on the other hand by the contour ring 9 and which has an outlet 35 to the suction chamber 29. A return connection 37 opens into the pressure chamber 3 3, via which a fluid under pressure passes from a consumer to the vane pump 1. The cross-section of the return connection is significantly larger than that of the outlet 35.

From Figure 1 it can be seen that between the pressure chamber 33 and the suction connection 27 there is a wall section 39 which

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deflects the fluid flowing into the suction chamber 29, which may also cause a cross-sectional narrowing in the transition area between the return connection 37 or pressure chamber 33 and the suction chamber 29, so that fluid flowing from the return connection 37 into the suction chamber 29 is accelerated.

Fluid or hydraulic oil flowing out of the outlet 35 entrains the hydraulic oil present in the area of the suction connection, i.e. the pressurized fluid returned directly from the consumer to the pump transfers its energy to the fluid entrained from the suction connection.

Since the cross-section of the suction chamber 29 after the outlet 3 5 is significantly larger than the cross-section of the outlet itself, an energy conversion takes place in the suction chamber, due to which a charging pressure is established in the suction chamber 29, which acts as far as the suction areas 17 and 19, so that the vane cell pump 1 can suck in the fluid with little cavitation.

A modified embodiment of a vane pump is shown in Figure 2. The same parts are provided with the same reference numbers, so that a detailed description can be omitted.

In the embodiment shown here, the vane pump 1 also has a rotor 3 that is rotatably mounted within a contour ring 9. The suction areas 17 and 19 of the two pump sections

· ■·

-6-

are indicated by dashed lines, as are their pressure areas 21 and 23. For better clarity, wings 7 have not been shown here.

In the embodiment shown here, the return connection 37 opens into a pressure chamber 33 arranged at a distance from the contour ring 9, which opens to the suction connection 27 via outlets 35a and 35b. The cross-section of the outlets 35a and 35b is significantly smaller than that of the return connection 37. Liquid conveyed through the return connection 37 into the pressure chamber 33 therefore exits through the outlets 35a and 35b at a significantly higher speed than is the case in the return connection 37.

The liquid entering the suction connection 27 at high speed entrains the fluid present there and transfers its energy to this fluid. The wall section 39 results in an optimal mixing of the two fluids, so that the energy of the fluid supplied under excess pressure through the return connection 37 is optimally transferred to the fluid in the suction connection 27.

The outlets 35a and 35b are arranged and designed in such a way that liquid exiting them does not hit the opposite boundary wall 41 of the suction connection, which would lead to energy losses. The boundary wall 41 is part of a pipe connection running perpendicular to the plane of the image, which leads to the tank.

-7-

The wall section 39 also narrows the suction connection 27 in the transition area to the suction chamber 29, so that a mixing chamber is formed here. The narrowing accelerates the fluid flowing through it. After the end of the wall section 39, the cross section of the suction chamber 29 increases, so that a charging pressure is built up here due to the energy conversion, due to which the fluid is introduced into the suction areas 17 and 19 with an overpressure.

The embodiment of the vane pump 1 shown in Figure 2 is characterized by the fact that the wall section 39 separates the interior of the pump, which accommodates the rotor 3, from the return connection 37 and from the suction connection 27, so that when the vane pump 1 is at a standstill, it is reliably prevented from running dry. The rotor is therefore completely immersed in the fluid even after the pump has been stopped and is therefore characterized by optimal start-up behavior. In other words, it is ensured that the vane pump 1 does not run dry when started and immediately starts pumping the fluid. It is important, however, that the connection between the suction connection 27 and the suction chamber 29 and the pressure outlet of the pressure kidneys 21 and 23 connected to the working pressure side of the vane pump 1 are arranged so high up that an oil collection chamber is created. The oil present there improves the starting properties of the pump.

· 1

-8th-

From the description of Figures 1 and 2 it is immediately apparent that the vane pump 1, as well as the roller cell pumps and gear pumps of a similar design not mentioned in detail here, do not have a flow control valve, as is usual in conventional pumps of the type mentioned here and as used, for example, in vane pumps for power steering systems. Such flow control valves are complex in design and involve high manufacturing costs. Moreover, charging of the suction chamber of pumps that are equipped with a flow control valve can only be guaranteed if the flow control valve has responded and directs a fluid from the pressure side of the pump directly back to its suction area.

In contrast, the structure of the pumps described in Figures 1 and 2 is significantly simplified. In addition, the charging of the suction area is always guaranteed when a fluid under pressure is returned from the consumer.

The pumps described in Figures 1 and 2 are therefore characterized by a very simple design. By charging the suction area with the help of the consumer's pressurized fluid, cavitation in the suction area of the pump is avoided with a high degree of certainty, so that noise and wear are greatly reduced and the speed limit of the pump can be increased.

Claims (7)

Gleiss & Große Patient Law Firm Stuttgart Berlin Hamburg Claims 1. Pump, namely roller cell pump or vane cell pump for supplying a consumer with a fluid, characterized in that pressurized fluid returned by the consumer is used to charge the suction area (29). 2. Pump according to claim 1, characterized in that the fluid returned by the consumer is guided into a pressure chamber (33) which has an outlet opening to the suction chamber (29) in the pump (1) (35; 35 a; 35 b) whose cross section is smaller than the cross section of the channel supplying the fluid. 3. Pump according to claim 1 or 2, characterized in that the suction chamber (29) is in fluid connection to a suction connection (27) via which a fluid is sucked in from a tank. 4. Pump according to one of the preceding claims, characterized in that the cross section of the suction chamber (29) is larger than the cross section of the outlet (35; 35a; 35b). 12 607Gt-ho 13. Seplombei \99i> I i.· i &idigr;&iacgr;&idgr;&idgr; · ··· -2- 5. Pump according to one of the preceding claims, characterized in that the outlet (35a; 35b) of the pressure chamber opens directly into the suction connection (27). 6. Pump according to one of the preceding claims, characterized by a wall section (39) delimiting the suction area (29) of the pump (1) from the suction connection (27). 7. Pump, namely a gear pump for supplying a consumer with a fluid, characterized in that pressurized fluid returned from the consumer is used to charge the suction area.