DE102007000970B4 - Positive displacement pump with pressure chamber seal - Google Patents

Abstract

Positive displacement pump (1) with variable displacement, in particular one-stroke vane pump, for generating a pressure medium flow to a consumer, with a housing (2) in which a rotor (4) is mounted, with a rotor ring (4) surrounding cam ring (6) and with between the rotor (4) and the cam ring (6) delimited by rotor elements working chambers (10) whose volume is adjustable by changing the eccentricity between the rotor (4) and cam ring (6), wherein the cam ring (6) of a in the Housing (2) arranged outer ring (3) is surrounded, which holds the cam ring (6) freely, wherein between the outer ring (3) and the cam ring (6) two pressure chambers (19, 20) are formed, wherein the pressure chambers (19, 20) against each other by a in a groove (180) guided seal (21) are sealed, which is designed as a multi-membered seal (21), wherein the seal (21 ') is formed at least in two parts, characterized in that the di (21 ') has a cross-sectionally triangular support strip (200') and an opposite triangular sealing strip (210 '), wherein the strips (200', 210 ') are movably and hingedly connected to each other, and wherein the strips (200', 210 ') are formed articulated interlocking.

Description

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

In practice, in work systems with hydraulic consumers, for example in power steering of motor vehicles, u.a. also worked with constant pumps. The speed caused by the drive of the pump via the internal combustion engine of the vehicle resulting excess amounts are relaxed and returned to the suction side of the pump, which in particular at higher speeds significant losses and heat loads are connected. However, these are accepted in order to have at any time the maximum consumer demand corresponding, large volume flows available, thus ensuring a delay-free admission of the respective hydraulic consumers.

Instead of constant displacement pumps are therefore often pumps with variable displacement used. When referred to as variable displacement pumps can be adjusted or adjusted by a displacement of the cam ring or the cam ring within the housing, the eccentricity between the rotor and the cam ring. Thus, the geometric displacement of the working chambers can be increased or decreased. The term "geometric" delivery volume refers to the per revolution funded volume of the positive displacement pump. In an adjustable vane pump, the geometric displacement is determined by the difference between the smallest and largest cell. The volume of a single working chamber or cell is changed by the eccentricity between the rotor and the cam ring and / or by the rotation of the rotor.

From the DE 10 2007 013 835 A1 is a variable displacement displacement pump in the form of an adjustable vane pump known. For generating a pressure medium flow to a consumer, the pump is provided with a housing in which a rotor is mounted and a rotor ring encircling ring is provided. In addition, between the rotor and the cam ring delimited by rotor elements working chamber is provided whose volume is adjustable by changing the eccentricity between the rotor and cam ring, wherein the cam ring is surrounded by a housing disposed in the outer ring, which keeps the cam ring free. Between the outer ring and the cam ring two pressure chambers are formed, which are sealed against each other by a guided in a groove seal, which is designed as a multi-membered seal at least two parts.

From the DE 10 2005 043 252 A1 For example, such a positive displacement pump is known. It is a positive displacement pump with a variable displacement, which may be formed, for example, as a single-stroke vane pump, and which is provided for generating a pressure medium flow to a consumer, with a housing in which a rotor is mounted, wherein the pump enclosing the rotor Curved ring and between the rotor and the cam ring by rotor elements delimited working chambers whose volume is adjustable by changing the eccentricity between the rotor and cam ring. For this purpose, the cam ring is surrounded by an outer ring arranged in the housing, which holds the cam ring free, wherein two pressure chambers are formed between the outer ring and the cam ring. In this pump, it is thus provided for adjusting the cam ring, that between the housing and the cam ring two mutually delimited and substantially opposite pressure chambers are formed. The pressure chambers can be acted upon with a fluid pressure. The cam ring is displaced accordingly as a function of the pressure chamber acted on by the fluid pressure, so that the geometric delivery volume is reduced or increased. It is provided that the cam ring is shifted at high speeds such that the geometric delivery volume is reduced. Conversely, it is provided at low speeds that the cam ring is moved so that increases the geometric displacement.

In the US Pat. No. 4,032,159 A There is described a multi-membered gasket triangularly shaped in cross-section with soft elastomeric material disposed in the groove between moving machine parts.

The US Pat. No. 3,614,114 , US describes a multi-membered gasket triangularly shaped in cross-section, with an elastic gasket and plastic gaskets provided to form a fluid-tight assembly.

The US 4,380,342 shows a two-part seal, wherein the two parts are each trapezoidal in cross section.

The DE 103 01 345 discloses a sealing arrangement in which a trapezoidal sealing element is arranged in a groove. The sealing element is biased by two pressing elements.

The US 4,556,223 deals with a three-part sealing system, which is arranged in a circle on a ring.

The US 1,175,383 describes a three-membered sealing arrangement with which a piston is sealed against a cylinder.

In the known pumps has been shown that the seal between the two pressure chambers must be particularly resistant to wear and permanently configured.

Therefore, the present invention has for its object to provide a positive displacement pump in which such a seal can be achieved with inexpensive means.

The problem is solved by a positive displacement pump with the features of claim 1.

Accordingly, it is proposed that the seal has a cross-sectionally triangular support strip and an opposite triangular sealing strip, wherein the strips (support strip and sealing strip) are movably and / or hingedly connected to each other, and wherein the strips are formed articulated interlocking.

It is advantageous if the multi-membered seal is in three parts, is formed, wherein the seal has two triangular in cross-section support strips, which are arranged spaced from each other, and between the support strips wedge-shaped engaging sealing strip. In this context, it is advantageous if the triangular support strips are arranged to be axially displaceable relative to each other against the groove flanks of the groove. It is also advantageous if the triangular support strips are designed to cover overlapping, wherein preferably, the sealing strip is arranged axially displaceably supported against the groove bottom.

The multi-membered or multi-part design of the seal allows a tolerance in relation to the sealing effect and realization in the groove structure or installation. Likewise, a wear-insensitive and cost-effective and durable seal between the pressure chambers or spaces is achieved by simple means.

These and other advantageous developments and refinements emerge from the further subclaims.

It is advantageous if one of the strips (support strip or sealing strip) has a bead-like elevation and the other of the strips has a matching groove-like depression. Alternatively, the strips (support strip and sealing strip) can also be movably connected to one another by means of a membrane.

Advantageously, when the at least one support strip is made of another, in particular pressure-stiffer, material than the sealing strip.

Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

the 1 shows a cross section through a positive displacement pump according to the invention;

the 2 shows in cross-section the embodiment of a three-part seal;

the 3 shows in cross-section the embodiment of a two-part seal;

the 4 shows in cross-section the embodiment of a one-piece seal; and

the 5 shows a cross section through a further positive displacement pump according to the invention.

The 1 shows an embodiment of a positive displacement pump according to the invention 1 with variable displacement. The pump is designed as a one-stroke vane pump for generating a pressure medium flow for a power steering device of a motor vehicle.

The vane pump 1 has a housing 2 into which an outer ring 3 (Also referred to as intermediate ring) is used. 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 settles on a flattening 7 or a thickening of the outer ring 3 unroll and thus in an elliptical space 8th in the outer ring 3 is formed, move.

The curve ring 6 is inside the elliptical space 8th 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, the wings become 9 in slots of the rotor 4 advanced and withdrawn. For this purpose, a Hinterflügelfluiddruck is used in a known manner, which substantially to the ends of the slots in the rotor 4 guided wings 9 acts.

As it turned out 1 results, the cam ring 6 by a compression spring 17 pressed in the direction of maximum deflection. The compression spring 17 becomes mounted laterally and the necessary housing bore preferably with a screw 18 locked.

Between the outer ring 3 and the curve ring 6 are two crescent-shaped pressure chambers 19 . 20 educated. The pressure chambers 19 . 20 be at the bottom by the flattening 7 and in the upper part by a seal 21 or suitable sealing elements separated from each other. This allows pressurization of the two pressure chambers 19 . 20 a displacement of the cam ring 6 be brought about.

Like that 1 can also be seen, is a spring-loaded control piston 22 provided, via fluid connections 23 . 24 with the pressure chambers 19 . 20 connected is. For shifting the cam ring 6 become the pressure chambers 19 . 20 via the fluid connections 23 . 24 pressurized or can via the fluid connections 23 . 24 Fluid from the pressure-relieved pressure chamber 19 . 20 flow out. The fluid connections 23 . 24 are each in the embodiment of a bore 23a . 24a in the case 2 and a hole 23b . 24b in the outer ring 3 educated. The pressure chambers 19 . 20 can through the control piston 22 alternately with both the operating pressure of the pump and with a container port 32 or a suction channel are connected. Due to the resulting pressure difference in the pressure chambers 19 . 20 becomes the displacement of the cam ring 6 reached.

According to the invention is now the seal 21 designed such that a tolerance insensitive installation and a wear-resistant, cost-effective and durable seal between the pressure chambers or spaces 19 and 20 is created.

These are the pressure chambers 19 and 20 against each other by a in a groove of the outer ring 3 (or the curve ring 6 ) guided seal 21 are sealed, as a multi-membered seal 21 is trained.

In the 2 to 4 For this purpose, different embodiments are shown:
The 2 shows an example in which the multi-membered gasket 21 in a groove 180 of the outer ring 3 is realized and consists of several parts, namely three parts, is formed. The seal 21 comprises two cross-section triangular support strips 190 and 200 , which are arranged spaced from each other and each at one of the groove flanks 250 respectively. 260 as well as on the curve ring 6 issue. In addition, the three-piece seal includes 21 another between the support strips 190 and 200 wedge-shaped engaging sealing strip 210 in the middle of the bottom of the groove 270 is applied to the local area.

The essentially trapezoidal sealing strip 210 is axially against the groove bottom 270 slidably mounted supported against the outer ring. And the triangular shaped slats 190 and 200 are axially against the respective groove flank 250 respectively. 260 slidably supported, with the support strips 190 and 200 Spaltüberdeckend are executed and thus on the cam ring 6 lie sealingly and from the sealing strip 210 against the groove flanks 250 and 260 as well as the curve ring 6 be pressed.

In other words, the in 2 illustrated three-piece seal 21 from the two gap bridging arranged, triangular, in the groove 180 arranged supporting strips 190 and 200 as well as the sealing strip 210 , which in their facing each other, against the groove bottom 180 apart sides, wedge-shaped and groove bottom 270 starting intervenes. Because the seal 21 by the high pressure side pending pressure as well as by the low pressure side support strips 190 and 200 axially in the direction of the low pressure side and also acted upon radially, is thus on the support between the respective low pressure side support bar 190 respectively. 200 and the sealing strip 210 created both a sealing limit and an axial and radial clamping of these acting as a sealing boundary elements of the seal 21 reached depending on pressure. The inventive design of the seal 21 thus works with appropriate tension by the respective, pending pressure.

Preferably, the seal exists 21 from simple elements that can also be configured differently in terms of their stress in the material, with the support strips 190 and 200 in particular materials with a relatively high wear resistance or hardness, such as polyamides, are suitable. For the sealing strip 210 On the other hand, preference is given to using other materials, such as, for example, polytetrafluoroethylene, in particular fiber-reinforced polytetrafluoroethylene, so that no special processing of the groove bottom is used 270 is required and the groove 180 can be made as a grooved groove with little effort. As the 2 Illustrated are the support bars 190 and 200 in cross-section preferably formed as a right-angled triangles, to which the sealing strip 210 is dimensioned suitable and, for example, is trapezoidal. Preferably, the respective corner areas are cut off.

The illustrated seal 21 is realized as a sliding strip seal, with the two support strips 190 and 200 are formed equal to each other and with their right angles to the cam ring 6 standing legs each at one of the groove edges 250 respectively. 260 the U-shaped groove 180 issue. The support strips 190 and 200 are mirror-symmetrical one the groove 180 dividing plane and support inside over their respective leg the gap between the cam ring 6 and outer ring 3 covering up. Between these symmetrically opposed support strips 190 and 200 lies the trapezoidal sealing strip 210 whose base is the bottom of the groove 270 is assigned and its sides corresponding to the inclination of the triangular supporting strips 190 and 200 above the base or groove bottom 270 form an isosceles triangle, wherein in the illustrated embodiment according to 2 the corners of the triangular sealing strip 210 are cut.

The length of the base of the sealing strip 210 is smaller than the width of the groove 180 , so that in the pre-marked construction, the sealing strip 210 opposite the groove bottom 270 or in relation to the groove flanks 250 respectively. 260 adjoining support strips 190 respectively. 200 is axially displaceable.

Referring to the in 1 described starting situation with high-pressure side loading of the pressure chamber 20 prevails, in the situation according to the presentation after the 2 , right of the groove 180 a higher pressure than left of the groove 180 , This has the consequence that when changing the pressurization, so at a relative to the pressure chamber 19 constructive overpressure in the pressure chamber 20 the support bar 200 from the groove flank 260 lifts off and releases the inlet to the groove space, causing the sealing strip 210 against the support strip 190 is applied and the support bar 190 both by the action of the sealing strip 210 as is also acted upon directly by the pressurization axially and radially. This will be the support bar 190 against the groove flank 250 as well as against the circumference or the surface of the cam ring 6 pressed tightly. In the reversal of the direction of rotation of the steering shaft, and from the corresponding reversal of the displacement direction and the pressurization, corresponding conditions arise on the support strip 200 ,

In the context of the invention, it proves to be useful if the support strips 190 and 200 consist of a relatively hard and wear-resistant plastic material, such as a polyamide. For the sealing strip 210 proves to be advantageous as a material polytetrafluoroethylene, preferably polytetrafluoroethylene with fiber insert, for example, with a fiberglass insert of 20%, due to its good sliding properties with sufficient wear without special processing requirements on the surface of the groove bottom 270 even with a certain bias of the sealing strip 210 against the groove bottom 270 ensures a slight displacement of the same.

The sides of the sealing strip 210 preferably include an angle of the order of 60 DEG lies with the result of a corresponding inclination of the sides of the support strips 190 respectively. 200 ,

The inventive design of the multi-part seal 21 makes it possible whose elements, namely the support strips 190 and 200 as well as the sealing strip 210 be mounted with a comparatively low bias voltage or almost without bias, since the necessary tension for the sealing function is amplified pressure-dependent, so that stress-induced material fatigue or voltage-induced flow of the material is avoided.

The 3 shows a two-part design of the seal 21 ' , where in the groove 180 a triangular-shaped support strip 200 ' is provided, which is against a groove flank and against the surface of the cam ring 6 seals. Opposite is a triangular sealing strip 210 ' provided, which against the other groove flank and against the surface of the groove bottom and the outer ring 3 seals. Both bars 200 ' and 210 ' are hinged together.

This has the sealing strip 210 ' a bead-like or nose-shaped elevation 211 that fit into a recess 201 the support bar 200 ' intervenes. It is thus made an articulated connection in the manner of a tongue and groove connection. Because both bars 200 ' and 210 ' Made of elastic material, the compound is also elastic and thus adapts ideally to the circumstances. In addition, the installation is facilitated.

In the 3 is a one-piece design of the seal 21 '' shown. The seal 21 '' consists of a single largely rectangular sealing strip 210 '' which is subdivided into rib segments on at least one side. Ribs 212 are preferably designed trapezoidal and serve tolerance adjustment, in particular in the direction of the groove bottom of the groove 180 , Also this seal 21 '' is sliding in the groove 180 embedded.

In the 5 is another positive displacement pump 1' shown at the between the pressure chambers 19 ' and 20 ' also a seal according to the invention 21 is provided. Again, the seal 21 mehrgliedrig or formed in several parts and in the groove of the outer ring 3 realized.

The invention can be used in all types of pumps in which pressure chambers are to be sealed against each other. The description of the invention serves to illustrate the preferred embodiments, but is not to be understood in a sense limiting the scope of the invention.

LIST OF REFERENCE NUMBERS

1; 1'

Vane pump

2

casing

3

outer ring

4

rotor

5

wave

6

cam ring

7

flattening

8th

elliptical space

9

wing

10

working chambers

17

compression spring

18

screw

19.20

pressure chamber

21; 21 '; 21 ''

Seal (multi-limbed or multi-part)

22

spool

23

fluid communication

23a / b

 Bore in the housing or in the outer ring

24

fluid communication

24a / b

 Bore in the housing or in the outer ring

26

relief well

26a

opening

28

unloaded area of the control piston (sidecut)

32

container terminal

180

Groove in outer ring to receive the seal 21

270

groove base

250, 260

flanks

210; 210 '

 sealing strip

190, 200; 200 '

support strips

201

Recess in the support strip 200 '

211

Bead on sealing strip 210 '

212

Ribs on sealing strip 210 '

Claims (9)

Positive displacement pump ( 1 ) with variable delivery volume, in particular one-stroke vane pump, for generating a pressure medium flow to a consumer, with a housing ( 2 ), in which a rotor ( 4 ) is mounted, with a rotor ( 4 ) surrounding cam ring ( 6 ) and with between the rotor ( 4 ) and the cam ring ( 6 ) defined by rotor elements working chambers ( 10 ) whose volume is determined by changing the eccentricity between the rotor ( 4 ) and cam ring ( 6 ) is adjustable, wherein the cam ring ( 6 ) of one in the housing ( 2 ) arranged outer ring ( 3 ), which surrounds the cam ring ( 6 ), wherein between the outer ring ( 3 ) and the cam ring ( 6 ) two pressure chambers ( 19 . 20 ), wherein the pressure chambers ( 19 . 20 ) against each other by one in a groove ( 180 ) guided seal ( 21 ) sealed as a multi-membered gasket ( 21 ) is formed, wherein the seal ( 21 ' ) is formed at least in two parts, characterized in that the seal ( 21 ' ) a triangular in cross-section support strip ( 200 ' ) and an opposite triangular sealing strip ( 210 ' ), wherein the strips ( 200 ' . 210 ' ) are movably and articulated, and wherein the strips ( 200 ' . 210 ' ) are formed articulated interlocking. Positive displacement pump ( 1 ) according to claim 1, characterized in that the seal ( 21 ) is formed in three parts, wherein the seal ( 21 ) two in cross-section triangular support strips ( 190 . 200 ), which are arranged at a distance from one another, and one between the support strips (FIG. 190 . 200 ) wedge-shaped engaging sealing strip ( 210 ) having. Positive displacement pump ( 1 ) according to claim 2, characterized in that the triangular supporting strips ( 190 . 200 ) axially to each other against the groove flanks ( 250 . 260 ) of the groove ( 180 ) are arranged slidably supported. Positive displacement pump ( 1 ) according to claim 2 or 3, characterized in that the triangular supporting strips ( 190 . 200 ) are performed gap overlapping. Positive displacement pump ( 1 ) according to one of claims 2 to 4, characterized in that the sealing strip ( 210 ) axially against the groove bottom ( 270 ) of the groove ( 180 ) is slidably supported. Positive displacement pump ( 1 ) according to claim 1, characterized in that one of the strips (210 ') has a bead-like elevation ( 211 ) and the other of the strips (200 ') has a mating recess ( 201 ) having. Positive displacement pump ( 1 ) according to claim 1, characterized in that the strips are movably connected to each other by means of a membrane. Positive displacement pump ( 1 ) according to one of the preceding claims, characterized in that the at least one support strip ( 200 '; 190 . 200 ) made of a different, in particular stiffer, material than the sealing strip ( 210 '; 210 ) is made. Positive displacement pump ( 1 ) according to claim 1, characterized in that the multi-membered gasket ( 21 '' ) is formed in one piece, wherein the seal ( 21 '' ) as one with ribs ( 212 ) provided sealing strip ( 210 '' ) is formed, the one the seal ( 21 '' ) forming the rib area.

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