EP0906512A1

EP0906512A1 - Vane pump

Info

Publication number: EP0906512A1
Application number: EP97929260A
Authority: EP
Inventors: Ivo Agner
Original assignee: LuK Fahrzeug Hydraulik GmbH and Co KG
Current assignee: LuK Fahrzeug Hydraulik GmbH and Co KG
Priority date: 1996-06-21
Filing date: 1997-06-23
Publication date: 1999-04-07
Anticipated expiration: 2017-06-23
Also published as: EP0906512B1; US6152716A; WO1997049915A1; JP4206132B2; DE19780598D2; JP2000512709A

Abstract

The invention concerns a vane pump with a rotor carrying vanes, with two pressure plates (17) resting tightly against the rotor, one located at the discharge end of the pump and the other at the other end, and with an annular structure which surrounds the vanes and forms two aspiration and pressure zones. At least one of the two pressure plates has inlet and outlet apertures (53, 59, 63a, b) which provide fluid communication between one pressure zone and an undervane zone. The invention is characterized in that the pressure plate (17.2) remote from the discharge end of the pump has an opening which provides fluid communication between one pressure chamber (61) partly delimited by this pressure plate (17.2), and seals off the pressure chamber (61) from the other pressure zone.

Description

Vane pump

description

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

Vane cell pumps of the type mentioned here are known. They have a rotor, in the circumferential wall of which slots that accommodate vanes are made. The rotor rotates within a contour ring, which preferably forms two crescent-shaped delivery spaces, which are traversed by the flights. When the rotor rotates, the space becomes larger and smaller. The operation of the wing cell pump thus results in suction and pressure areas. With a contour ring of the type mentioned here, there are two separate pump sections, each with a suction area and a pressure area.

The lateral limitation of the pressure range takes place on the outlet or front side by means of a close-fitting pressure plate and on the side opposite the front side, for example by the housing of the wing cell pump. 7/49915 PCΪ7EP97 / 03277

If a vane cell pump is brought to a standstill at operating temperature, the wings above slide due to their gravity into the slots made in the rotor. This eliminates the separation between the suction and pressure areas; a short circuit is created in one, namely in the upper pump section. On the opposite side, the wings slide out of their slots following gravity, or they stay outside so that the separation is preserved here.

If the fluid required by the vane cell pump, for example hydraulic oil, cools, its viscosity increases, so that the mobility of the wings decreases. When the pump is started up, the still separate pump section demands the fluid. However, the delivery rate is greatly reduced, since there is a hydraulic connection between the conveying lower pressure area to the opposite upper pressure area and there to the suction area.

When the pressure areas are sealed by the housing, an undesirable leakage often occurs since the housing bends away from the rotor due to the pressure prevailing within the contour ring, and thus an increase in the leakage gap occurs. Leakage is reduced by using a further pressure plate instead of sealing by the housing. This is essentially identical to the pressure plate on the outlet or delivery side and in each case has channels opening into the pressure areas of the two pump sections, which channels connect to one between Manufacture pressure plate and housing formed pressure chamber.

The above-mentioned problem of a short circuit when the pump starts up occurs more frequently in this embodiment, since in addition to the connection on the customer side between the pressure ranges, there is also a corresponding hydraulic connection on the side opposite the front side.

It is therefore an object of the invention to provide a vane cell pump which has very good cold start properties and moreover has a very low tendency to leak.

This object is achieved with the aid of a Flugelzellen¬ pump, which comprises the features mentioned in claim 1. The vane cell pump has two pressure plates lying close to the rotor, the pressure plate opposite the front side having an opening which establishes a fluid connection between a preferably lower pressure area and a closed pressure chamber. As a result, pressure is built up in this pressure chamber, which bends the pressure plate slightly towards the rotor and presses it tightly against the rotor. The pressure built up in the conveying area leads in the same way to a force being exerted on the forward pressure plate which presses this pressure plate close to the rotor. In addition, a short circuit between the two pressure areas across the pressure space is avoided by the fact that only one of the two pressure areas is connected to the pressure space in the pressure plate opposite the front side. The other pressure range of the pump is sealed by the pressure plate to the pressure chamber.

In an advantageous embodiment, at least one of the fluid connections in the pressure plate opposite the delivery side has a passage area which is smaller than 1/3 of the passage area of the outlet opening of the delivery side pressure plate.

In a further advantageous embodiment of the invention, the pressure plate which closes the pressure chamber and which comprises an opening for connecting the lower pressure region to the pressure chamber has a further relatively small opening which flows from the pressure chamber into the other pressure region located above. With the aid of this opening, the pressure chamber can be vented when the pump is started up for the first time, with the advantageous result of a noise reduction. In order to prevent a short circuit via this venting opening, it must be designed in such a way that it has a very high hydraulic resistance for a cold fluid of high viscosity.

In a further advantageous embodiment, an opening is provided on the pressure plate opposite the delivery side, which connects the upper pressure area in the installed position to the pressure chamber. The pressure area located below is sealed off by the pressure plate from the pressure chamber.

An advantageous embodiment also consists in the pressure plate opposite the front side to be provided with two openings, each of which creates a connection between a pressure area and the pressure chamber and which have a high hydraulic resistance. The sum of the two resistances must exceed a value which is necessary to avoid a short circuit in the cold start phase.

Further advantageous embodiments of the invention result from the subclaims.

The invention is explained in more detail using exemplary embodiments with reference to the drawing. Show:

Figure 1 is a schematic sectional view of a vane cell pump;

Figures two pressure plates of the air cell pump, 2a, 2b and

Figures show schematic representations of four differently designed air cell pumps.

For a better understanding, the structure of a joint pump will first be discussed in general with reference to FIG. 1. This comprises a housing 1 in which a channel 3 leading to an outlet is provided. A consumer, for example a power steering device, is supplied with a fluid, for example hydraulic oil, via the outlet.

The housing has a circular interior 5, which has a contour ring 7 and a rotor 9. takes, in the circumferential pool wing 8 receiving slots are introduced. The rotor 9 is set in rotation by means of a drive shaft 11, so that the vanes 8 move within the contour ring 7, the interior 5 of which is designed in such a way that two crescent-shaped free spaces, which are also referred to as forward spaces, are formed by the Be flown through. Between each two adjacent flights - seen in the circumferential direction - there are so-called flight egg cells, which become smaller and larger when the rotor rotates. This creates suction and pressure areas. The end faces of the contour ring 7 and the rotor 9 rest on sealing surfaces which are formed by pressure plates 17.1 and 17.2. In the following, the pressure plate 17.1 facing the front side is referred to as the pressure plate on the customer side and the other pressure plate 17.2 as the pressure plate on the pressure chamber side. The unit formed from the two pressure plates 17.1 and 17.2, the contour ring 7 and the rotor 9 thus lies in the interior 5 of the housing. At least the pressure-side pressure plate 17.1 facing the channel 3 or outlet is designed such that the hydraulic oil required by the egg cells is required through the pressure plate and into an outlet area formed between the pressure plate and the inside of the housing and from there to the consumer.

The vane cell pump is constructed in such a way that the hydraulic oil in the pressure area reaches the underside of the wing lying in the interior of the rotor - the so-called lower wing area - and pressurizes it. By in the lower wing area prevailing overpressure, the wings are pressed radially outward from the slots and thus lie sealingly on the inside of the contour ring.

The surfaces of the two pressure plates 17.1 and 17.2 facing the rotor 9 are shown in plan view in FIG. 2a or 2b. Two suction areas 21 and two kidney-shaped pressure areas 23 can be clearly seen in each case. Further inside, in the pressure plate-side pressure plate 17.2 according to FIG. 2a, an essentially annular groove 25 is provided for the lower wing areas. In contrast, four independent, essentially annular segment-shaped grooves 27 are formed in the pressure plate 17.1 according to FIG. 2b.

FIG. 2a also shows that the kidney-shaped pressure areas 23 of the pressure plate-side pressure plate 17.2 merge into round channels 29. At least one or both channels 29 have a passage area, that is to say a cross-sectional area through which flow passes, which is less than 1/3 of the passage area of the pressure areas 23 of the pressure plate 17.1 on the forward side.

In FIG. 3, four different embodiments of the vane cell pump are shown in a highly simplified manner, with the different configurations of the pressure plates being essential. For this reason, the remaining details, in particular the rotor, blades, shaft, etc., are not shown.

The vane cell pump according to FIG. 3a has both on the outlet or front side F of the rotor also on the opposite pressure chamber side D a pressure plate 17.1 or 17.2. Both pressure plates 17 lie close to the contour ring and rotor 51 and are thus intended to prevent leakage of hydraulic oil from the pressure areas.

The illustration of the pressure plate 17.1 on the outside in FIG. 3a shows two outlet channels 53.1 and 53.2, each of which establishes a fluid connection between a pressure area and a claims or outlet area 55.

The pressure plate 17.2 on the pressure chamber side bears against the rotor 51 on the opposite side. It also has a channel 59 which establishes a fluid connection between a pressure region UD, which is lower in the figure, and a pressure chamber 61. This pressure chamber 61 is formed on the one hand by the pressure plate 17.2 on the pressure chamber side and on the other hand by the housing.

In the pressure chamber-side pressure plate 17.2, further openings 63a, 63b are also provided, which open into the respective lower wing area of the wings. This creates a fluid connection between the lower pressure area and at least one lower wing area.

It can be clearly seen in FIG. 3a that the pressure plate 17.2 on the pressure chamber side has no channel assigned to an upper pressure region OD in the figure. This upper pressure range is therefore not connected to the pressure chamber 61. A short circuit in the start-up phase between the upper pressure range in which the short circuit prevails and the lower one Print area is prevented in this way. It is assumed that appropriate measures to prevent a short circuit are also taken on the front side. For example, hydraulic resistors on the front side designed as webs or plates prevent fluid from flowing from the lower pressure region into the upper pressure region or the outlet region in the cold start phase.

The embodiment shown in FIG. 3b differs from the one described above only in that the opening 63 opening into the lower wing area is not provided in the pressure plate 17.2 on the pressure chamber side but in the pressure plate 17.1 on the forward side. In addition, the channel 59 of the pressure plate 17.2 is not assigned to the lower pressure area but to the upper pressure area. However, this does not change the mode of operation of the two pressure plates after the start-up phase.

A third embodiment can be seen in FIG. 3c, which essentially corresponds to the embodiment shown in FIG. 3a.

It differs, however, in that in the pressure plate 17.2 on the pressure chamber side there is a small channel 65, which essentially serves for ventilation and creates a connection between the pressure chamber 61 and the upper pressure region. The cross section of the channel 65 is dimensioned so that its hydraulic resistance is very high, especially for cold hydraulic oil with a high viscosity. Resistance should be on everyone Case should be so large that in the cold start phase an oil flow from the lower pressure area via the pressure chamber 61 and the channel 65 to the upper pressure area, where the short circuit prevails, and then to the suction area is almost prevented.

The function of this ventilation duct 65 is to allow air collecting in the upper region of the pressure chamber 61 to escape. Therefore, this ventilation duct 65 is to be assigned to the pressure range above. The venting of the pressure chamber 61 thus achieved makes it possible to reduce noise.

FIG. 3d shows a further exemplary embodiment in which the pressure plate 17.2 on the pressure chamber side has two channels 71. The upper channel 71.1 connects the upper pressure area to the pressure chamber 61, the lower channel 71.2 connects the lower pressure area to the pressure chamber 61. The cross sections of the two channels 71 are chosen so that the sum of the two individual hydraulic resistances for a viscous, cold oil is so large that almost no oil flow develops between the two pressure areas through the pressure chamber 61.

This makes the pump independent of the position with regard to the ventilation function, since there is a ventilation channel in the upper area of the pressure chamber regardless of the installation position, through which the accumulating air can escape.

FIGS. 3e and 3f show two further exemplary embodiments of how a hydraulic resistance can be implemented on the pressure chamber side, which for example, can be used instead of the small cross sections shown in Figure 3d. Thus, on the one hand, a web 77 can be provided on the housing, which limits the oil flow in the cold start phase between the lower and upper pressure range. In addition to the arrangement of the web 77 on the housing, this can of course also be formed on the pressure plate 17.2, as shown in FIG. 3f. Of course, other configurations of a hydraulic resistance are also conceivable.

Claims

Expectations

1. Fugal cell pump with a wing-receiving rotor, with two pressure plates (17) lying close to the rotor, one of which is arranged on a front side of the wing cell pump and one on the opposite side, and with a two suction surrounding the wings - Contour ring forming and pressure areas, at least one of the two pressure plates being provided with inlet and outlet openings (53, 59, 63a, b) which establish a fluid connection between a pressure area and a lower wing area, characterized in that the pressure plate (17.2) opposite the front side has an opening which creates a fluid connection between a pressure area and a pressure space (61) partially delimited by this pressure plate (17.2) and seals the pressure space (61) to the other pressure area.

2. Vane cell pump according to claim 1, characterized ge indicates that at least one of the fluid connections in the pressure plate (17.2) opposite the front side has a passage area which is less than 1/3 of the passage area of the outlet opening of the opposite pressure plate ( 17.1).

3. Fugelzellenpumpe according to claim 1 or 2, characterized in that the opposite side of the pressure plate (17.2) has a - in the installation position above - ventilation channel that connects the pressure chamber (61) with the other pressure area and is designed so that it has a large hydraulic resistance for a cold fluid with high viscosity.

4. Fugelzellenpumpe according to claim 1, 2 or 3, da¬ characterized in that in the opposite side of the pressure plate (17.2) openings (59,63) are provided which the fluid connection between a pressure area and at least one sub-wing area and simultaneously one Establish a fluid connection in the pressure chamber (61).

5. Fugelzellenpumpe according to claim 1, 2 or 3, da¬ characterized in that in the front-side pressure plate (17.1) openings are provided which produce the fluid connection between the pressure area and at least one sub-wing area, and that the pressure opposite the front side ¬ plate (17.2) seals the pressure chamber (61) towards the sub-flight area.

6. Fugelzellenpumpe according to claim 4 or 5, characterized in that the -related to the installation position- upper pressure area is in fluid communication with the pressure chamber (61).

7. joint cell pump according to claim 4 or 5, characterized in that the -related to the installation position- lower pressure area is in fluid communication with the pressure chamber (61).

8. Fugelzellenpumpe according to claim 1, 2 or 3, da¬ characterized in that both pressure areas are in fluid communication with the pressure chamber (61), wherein the connections in the opposite side of the pressure plate (17.2) are dimensioned so that the sum of the two hydraulic resistances for a cold fluid is so large that a fluid flow is prevented.

9. vane cell pump according to claim 8, characterized ge indicates that on the side of the front side opposite pressure plate (17.2) a web (77) is provided in the housing and / or in the pressure plate, which has a large hydraulic resistance to prevent a short circuit between forms the two pressure areas.