DE102005009658B4 - hydraulic power unit - Google Patents

Abstract

Hydraulic unit (HCU) comprising a receiving body with electrohydraulic valves (6-17), with at least one hydraulic pump (20, 21), and with channels for connecting the pump (20, 21) to at least one hydraulic consumer, the pump (20 , 21) a pulsation damper (18, 19) integrated in the receiving body, comprising a media separation element (31) made of elastic material, which separates a fluid chamber (30) from a pneumatic chamber (32), characterized in that the pulsation damper (18 , 19) is arranged between a pressure side (DS) of the pump (20, 21) and the hydraulic consumer, the pulsation damper (18, 19) having a single pneumatic chamber (32) which is separated from the dome-shaped media separating element (31) and a bore closure (33) provided with a central projection (36) is delimited, the central projection (36) of which with its cylindrical wall and its relative to the pneumatic comb he (32) concave bottom (38) protrudes into a receiving bore (29) in the receiving body, which has at least one rounded diameter step at least in the area of a bore bottom, the fluid chamber (30) from the receiving bore (29) in the receiving body and the media separating element (31), which protrudes with its convex protuberance (39) into the receiving bore (29) and with its concave protuberance (40) overlaps the central projection (36) to form the pneumatic chamber (32).

Description

The invention relates to a hydraulic unit comprising a receiving body with electrohydraulic valves, with at least one hydraulic pump, and with channels for connecting the pump to at least one hydraulic consumer, wherein the pump is associated with a, integrated in the receiving body, pulsation damper comprising a media separating element made of elastic material, which separates a fluid chamber from a pneumatic chamber.

Of the WO 97/14591 a generic hydraulic unit is to be taken with an active braking device, wherein between a master cylinder and a suction side of a pump Pulsationsdämpfer is arranged, which has a deformable membrane which separates a pressure medium-filled area of a gas-filled area (membrane damper), wherein the gas-filled area a closed chamber forms, and the chamber has a first portion which is accessible to the membrane, and a second portion which is inaccessible to the membrane, wherein a gas exchange between the two sections is possible.

From the DE 103 02 681 B3 is a hydraulic unit has become known, being provided for Pulsationsminderung Pulsation damping chambers, which are arranged as additional components - such as in particular sleeves - outside of the receiving body. Although in this way installation space is saved in the receiving body, so that the volume of the receiving body decreases, but the volume of each Pulsationsdämpfungskammer must be provided elsewhere. In the cited prior art, the Pulsationsdämpfungskammern extend to a side which serves for mounting a control unit. The Pulsationsdämpfungskammern protrude into an area of the electronic control unit. In other words, the installation space for the electronic control unit is restricted by the selected arrangement of the pulsation damping chambers. This is particularly the case when the damping chambers are to be formed large volume, in order to optimize their effectiveness.

Basically, the same disadvantages apply to a diaphragm damper, as he, for example, from the DE 39 12 937 A1 is known. The diaphragm damper is provided as a separately preassembled unit arranged outside the receiving body, and comprises an elastomeric molded part placed in a self-contained housing as a media separating element, which separates a hydraulically actuated pressure chamber from a cavity which is pneumatically in communication with the ambient atmosphere.

The DE 195 24 921 A1 describes a vibration damper with a membrane, wherein the membrane is formed as a hollow cylindrical molded part with a shell wall and a bottom, and wherein between the shell wall of the molding, and a head of a support body and a collar of a closure member, a cavity is formed, which is connected to the ambient atmosphere , Such vibration dampers have the disadvantage that their elasticity decreases with increasing operating time, which adversely affects the damping behavior.

From the DE 199 10 100 A1 is a vibration damping device used in a cavity of a valve block is known, which has a pot-shaped membrane whose edge is clamped between a step and a closure part. On the side facing away from the fluid side, the membrane is ventilated via a bore in the closure part, so that a rubber body accommodated in the cup-shaped membrane is exposed to the atmospheric pressure.

Further, go out DE 196 26 305 A1 a hydraulic brake system with a diaphragm damper inserted in a housing forth, the membrane is designed cup-shaped, wherein the inner volume of the pot is connected to a hydraulic line. The cup-shaped membrane is supported with its outwardly curved pot bottom on a housing closure cover, which is provided with a hollow cylindrical extension which presses a diaphragm provided on the membrane against a housing stop for fixing the membrane in the housing.

It is an object of the present invention to improve the effectiveness of Pulsationsminderung in a hydraulic unit with little effort over the entire operating time, and to reduce the installation volume of the damping means as well as good conditions for evacuation and subsequent filling with fluid intended for Pulsationsminderung area within to create the hydraulic unit.

The object is achieved in a hydraulic unit of the specified type with the feature combination of claim 1.

The pulsation damper is located between the pressure side of the pump and the hydraulic consumer, and has a single closed pneumatic chamber. Advantageously, the number of components is still pleasingly low while still easily adjustable damping effect. A particular advantage of the invention lies in the fact that a vehicle brake system according to the invention, even after a membrane crack remains functional, and only a comfort restriction due to loss of damping function occurs. Because a contamination of the brake system by air or moisture is not to be feared. An adjustment of the damping effect is simple and feasible in a systematic manner by changing the geometry, preload or Shore hardness of the media separating element as well as by changing the pneumatic pressure conditions in the pneumatic chamber. The diaphragm damper is thus comparatively easily adapted to a variety of applications.

Rounding off and rounding off the bore stages of the receiving bore enables a vacuum filling of the pulsation damper.

By having the bore closure means for centering the medium separating element, the mounting of the damper is facilitated because slippage of the elastic material is prevented.

When the bore closure is formed as a lid with a substantially disc-shaped base and a central projection, this allows a cost-effective production using cutting or non-cutting manufacturing processes such as extrusion molding in particular.

However, the central projection not only has the function of centering the media separating element during assembly. For a bottom of the central projection is concave to support the media separating element.

This increases the usable compression space in the pneumatic space in a manner which also benefits the life of the membrane. Because the concave bottom design also allows a largely centrally attacking and zukzessiv increasing centering effect, even if the membrane is applied under the action of high, hydraulically pulsating forces jerky pulsating to the ground. This measure reduces the risk of membrane rupture. An additional, equally effective measure are generous, symmetrical circumferential fillets in the transition between base, wall and floor.

In principle, the bore closure is positively connected to the receiving body, in particular screwed, caulked or clinched. If the media separating element bears firmly against a bore step of the receiving bore, a defined compressive stress within the media separating element can be achieved by a defined insertion depth of the bore closure in relation to the media separating element, in order to adjust the damping effect in this way. The bore plug is pressed onto the media separator for assembly and, in parallel, the required forces are determined and, finally, the bore seal is determined when the desired compressive stresses are achieved in the media separator.

According to an advantageous embodiment of the invention, the media separating element is formed dome-shaped, and projects with a convex protuberance into the receiving bore to engage with the opposite concave protuberance the central projection to form the pneumatic chamber. The dome shape of the media separation element allows an optimized-centric initiation of the hydraulic pressure forces by self-cancel opposing force vector portions, while adding axially directed force vector components.

For space-neutral increase of the usable compression space of the pneumatic chamber has this between the media separation element and bore closure a lenticular cross-section, preferably in addition to the lenticular cross-section is still a parallel to the wall of the central projection extending, cylindrical area.

For adaptive adaptation to other environmental conditions, the pulsation damper may be provided in series or parallel to a superimposed pulsation damping chamber.

Further details, and advantageous effects of the invention will become apparent from the following description with reference to an embodiment.

In the drawing shows:

1 a schematic hydraulic circuit diagram with a hydraulic unit using the example of a slip-controlled vehicle brake system, and

2 an enlarged sectional view of a diaphragm damper in the uncompressed idle state.

The 1 illustrates the relationships of a hydraulic interconnection and function of a slip-controlled motor vehicle brake system 1 with two brake circuits the wheel brakes 2 - 5 comprise and with a block-shaped hydraulic unit (HCU) comprising electro-hydraulic components such as valves 6 - 17 , Channels and pulsation dampers 18 . 19 of the membrane type integrated in the hydraulic unit between a pressure side DS of a hydraulic pump 20 . 21 and a hydraulic consumer such as in particular the wheel brakes 2 - 5 or a master cylinder 22 is provided. In improvement of this hydraulic interconnection, it is according to 1 quite conceivable, the pulsation damper 18 . 19 in series, ie before, after or parallel to a Pulsationsdämpfungskammer 23 . 24 provide, without departing from the general inventive idea.

In a basic function are the wheel brakes 2 - 5 with the help of the master cylinder 22 Conventionally actuated. The pump 20 . 21 has a suction path and a pressure path to allow ABS or ESP control intervention. The pressure side DS of the pump 20 . 21 flows into a brake line 25 . 26 one which the. wheel brakes 2 - 5 with the master cylinder 22 combines. Both in the brake line 25 . 26 as well as in each case in further. Pressure medium channels are the valves 6 - 17 provided, the pressure build-up, pressure maintenance and pressure reduction phase in the wheel brakes 2 - 5 can regulate.

Below we will detail the 2 received. The block-shaped hydraulic unit HCU comprises the receiving body, which is the essential hydraulic components namely namely the electro-hydraulic valves 6 - 17 , the pump 20 . 21 as well as low pressure storage 27 . 28 and the pulsation dampers 18 . 19 receives.

For integrated accommodation of a pulsation damper 18 . 19 , is a stepped receiving bore 29 provided on the pressure side DS of the pump 20 . 21 is integrated in the brake system. For the hydraulic connection opens a not further shown or designated channel radially or axially into the receiving bore 29 ,

Within the mounting hole 29 is a fluid chamber 30 housed, which of the wall of the receiving bore 29 as well as the media separator 31 is limited from elastic material. Within the mounting hole 29 there is also a pneumatic chamber 32 that of the media separator 31 and from a bore lock 33 is limited. The pneumatic chamber 32 is preferably hermetically separated from the ambient atmosphere by the media separator 31 close to the hole closure 33 and a bore stage 34 rests, and by the bore closure 33 and the receiving body positively interlocked verclincht, caulked or screwed. The pneumatic chamber 32 and the fluid chamber 30 are adjacent to each other and have the media separator 31 as a common wall.

Again 2 can still be found, is the pulsation damper 18 . 19 of the membrane type. To mount the pulsation damper 18 . 19 To simplify, is the bore closure 33 with centering for the media separator 31 Mistake. Slipping of the media separating element 31 when fixing the hole lock 33 is prevented in this way. For the centering is essentially a right angle of a disc-shaped base 35 prominent central projection 36 , which in the receiving bore 29 protrudes. The central projection 36 has a substantially cylindrical wall 37 and a floor 38 , which in relation to the pneumatic chamber 32 is concave.

Furthermore, all transitions are between base 35 , Wall 37 and soil 38 each provided with symmetrical circumferential fillets with wide radius of curvature R. As a result, in operation a wrinkle-free system of the media separating element 31 at the hole closure 33 allows.

Again 2 can still be removed, has the mounting hole 29 at least at a bore bottom over a generously rounded diameter stage with a wide radius of curvature R. This fillet is in the intended use (with a hydraulic pressure within the fluid chamber 30 ) basically without function. However, this additional feature allows after brake system production, a first-time vacuum filling of the brake system and in particular of the pulsation damper 18 . 19 with the respective fluid. Because motor vehicle brake systems 1 are filled at the vehicle manufacturers only after an evacuation with the pressure medium. Under the effect of a negative pressure, however, there is a risk that the media separator 31 deep into the mounting hole 29 is sucked in. The rounding described in this context reliably prevents punching damage or pinching of the media separating element 31 , Basically, it therefore makes sense, all cross-sectional transitions of the receiving bore 29 to fill in with fillets.

The media separator is naturally heavily loaded. A membrane tear would cause a loss of damping effect. Against this background, the thickness of the media separating element 31 comparatively large, and is more than the thickness of the central projection 36 ,

For an optimized introduction of force into the media separator 31 this is dome-shaped with a convex protuberance 39 and with a concave protuberance 40 educated. The convex protuberance 39 protrudes into the mounting hole 29 into it, and the concave protuberance 40 overlaps the central projection 36 to form the pneumatic chamber 32 ,

To make best use of the available installation space, the pneumatic chamber has 32 a lenticular cross section. This shaping also results in a centered installation of the media separating element 31 on the concave bottom 38 from the central projection 36 , The usable space of the pneumatic chamber 32 is extended if, in addition to the lenticular cross-section still one parallel to the wall 37 of the central projection 36 extending, cylindrical area 41 having.

It should be noted that the pneumatic chamber 32 can be filled with air or gas, the pressure of which is adapted to the particular circumstances. Preferably located in the pneumatic chamber 32 Air under a pressure of 1 bar.

LIST OF REFERENCE NUMBERS

1

Motor vehicle brake system

2

wheel brake

3

wheel brake

4

wheel brake

5

wheel brake

6-17

Valve

18

pulsation dampers

19

pulsation dampers

20

pump

21

pump

22

master cylinder

23

Pulsationsdämpfungskammer

24

Pulsationsdämpfungskammer

25

brake line

26

brake line

27

Low-pressure accumulator

28

Low-pressure accumulator

29

location hole

30

fluid chamber

31

Media separating element

32

pneumatic chamber

33

hole closure

34

bore step

35

Base

36

Central projection

37

wall

38

ground

39

convex protuberance

40

concave protuberance

41

cylindrical area

DS

pressure side

SS

suction

HCU

hydraulic power unit

Claims (8)

Hydraulic unit (HCU) comprising a receiving body with electro-hydraulic valves ( 6 - 17 ), with at least one hydraulic pump ( 20 . 21 ) and with channels for connecting the pump ( 20 . 21 ) with at least one hydraulic consumer, wherein the pump ( 20 . 21 ), integrated in the receiving body, pulsation damper ( 18 . 19 ) comprising a media separating element ( 31 ) is assigned from elastic material, which is a fluid chamber ( 30 ) of a pneumatic chamber ( 32 ), characterized in that the pulsation damper ( 18 . 19 ) between a pressure side (DS) of the pump ( 20 . 21 ) and the hydraulic consumer is arranged, wherein the pulsation damper ( 18 . 19 ) a single pneumatic chamber ( 32 ), which of the dome-shaped medium separating element ( 31 ) and one with a central projection ( 36 ) provided bore closure ( 33 ) whose central projection ( 36 ) with its cylindrical wall and its relative to the pneumatic chamber ( 32 ) concave bottom ( 38 ) in a receiving bore ( 29 ) protrudes in the receiving body, which has at least in the region of a bore bottom at least one rounded diameter stage, wherein the fluid chamber ( 30 ) from the receiving bore ( 29 ) in the receiving body and the media separating element ( 31 ) is limited, with its convex protuberance ( 39 ) in the receiving bore ( 29 ) protrudes as well as with its concave protuberance ( 40 ) the central projection ( 36 ) to form the pneumatic chamber ( 32 ) overlaps. Hydraulic unit according to claim 1, characterized in that the bore closure ( 33 ) as a lid with a disc-shaped base ( 35 ) is trained. Hydraulic unit according to claim 2, characterized in that all transitions between base ( 35 ), Wall ( 37 ) and ground ( 38 ) are each formed with symmetrical circumferential fillets. Hydraulic unit according to claim 1, characterized in that the bore closure ( 33 ) and the receiving body positively interlocked with each other, caulked or screwed. Hydraulic unit according to claim 1, characterized in that that of the ground ( 38 ) of the central projection ( 36 ) and the media separator ( 31 ) defined pneumatic chamber ( 32 ) has a lenticular cross-section. Hydraulic unit according to claim 1, characterized in that the pneumatic chamber ( 32 ) in addition to the lenticular cross-section still one parallel to the wall ( 37 ) of the central projection ( 36 ), cylindrical region ( 41 ) having. Hydraulic unit according to claim 1, characterized in that the pneumatic chamber ( 32 ) is filled with gas, in particular air under a pressure of 1 bar. Hydraulic unit according to claim 1, characterized in that the pulsation damper ( 18 . 19 ) in series or parallel to a pulsation damping chamber ( 23 . 24 ) is provided.

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