EP2054284A2

EP2054284A2 - Servobrake

Info

Publication number: EP2054284A2
Application number: EP07788297A
Authority: EP
Inventors: Stephan Becker
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 2006-08-17
Filing date: 2007-08-07
Publication date: 2009-05-06
Also published as: US20100192763A1; KR20090052879A; US8297178B2; WO2008019974A3; DE102006053142A1; WO2008019974A2; JP2010500945A

Abstract

The invention relates to a servobrake for motor vehicles, the control valve (12) of which can be actuated by means of an electromagnet (20), independently of an actuating rod (7) that displaces a valve piston (9), said electromagnet actuating a third seal seat (24) that permits the ventilation of the working chamber (4). The third seal seat (24) is configured on a sleeve (32) that cooperates with the electromagnet (20). An annular element (36), that is arranged so that it can be displaced in relation to the third seal seat (24), is supported on the sleeve (32) by means of an elastic or compressible element (37). According to the invention, in order to improve the noise behaviour of the servobrake, the annular element (36) comprises means for guiding an air flow (L) produced during normal braking in the direction of the working chamber (4).

Description

Brake booster

The invention relates to a brake booster for motor vehicles with an amplifier housing, the interior of which is divided by a movable wall into a vacuum chamber and a working chamber, and with a movable wall supporting the control housing, in which a control valve is arranged, which acts on the movable wall on a pneumatic Pressure difference controls and actuated both by an actuating rod by means of a valve piston and independently of the actuating rod by an electromagnet and consists of three concentrically arranged sealing seats and a cooperating with the sealing seats, provided with axial passages valve body, wherein the first sealing seat in the control housing and the second sealing seat on the valve piston are formed, while the third sealing seat is formed on a, cooperating with the electromagnet sleeve, and wherein a relative to the third sealing seat slidably angeo rdnetes ring member is provided, which is supported with the interposition of an elastic or compressible element on the sleeve, the valve body facing the edge region by radial openings separate sections, via which it is in contact with the valve body, and in the release position relative to the third sealing seat is arranged offset axially to the valve body, wherein the ring member is disposed radially within the sleeve, that its partial regions, via which it is in contact with the valve body, at least partially release the passages provided in the valve body. Such a brake booster is known from WO 2006/005742 Al. In the previously known

However, brake booster occur in normal braking operation as disturbing noises. This negative noise behavior is due to the air flow of the air flow at edges of the sleeve or turbulence of the air flow when flowing on the second sealing seat towards working chamber by unilateral lifting of the second sealing seat from the valve body, the turbulence cause in a space of the valve body an oscillating Air column arises. Furthermore, it is considered negative that the turbulence has a negative influence on the response and release time dynamics of the brake booster.

It is therefore an object of the present invention to provide an improved brake booster with regard to its noise behavior and flow conditions.

This object is achieved in that the ring member comprises means for guiding a occurring during a normal braking air flow in the direction of working chamber. The funds allow a targeted guidance of the air flow, so that the noise behavior and the flow conditions can be positively influenced.

Preferably, the means allow a guidance of the air flow along an inner side of the ring element. The air flow is thereby directed targeted and without detours or air change in the direction of the working chamber. In the best case, this could improve the response and release dynamics can be achieved. To concretize the inventive concept, an advantageous development of the invention provides that the ring element has at its, the valve body end facing a circumferential ring which is flush with the sub-areas in the axial direction, wherein the ring covers a radial inner side of the passages in the radial direction. A sweeping the passages of the valve body and thus the emergence of a vibrating air column within the valve body can be excluded.

Preferably, the ring is provided integrally connected to the sub-areas of the ring element, whereby an additional assembly of the ring can be omitted.

A simple and inexpensive production of the ring element is achieved in that the ring element is provided with the ring as a one-piece injection molded part.

For the metered reduction of the controlled in the booster housing of the pneumatic brake booster pneumatic pressure and stabilization, according to an advantageous embodiment of the invention, the areas of the ring member on a larger wall thickness, wherein at least a portion of the portions is provided with the valve body facing recesses. As a result, in the case of a regulated pressure reduction phase, the suction of the atmosphere from the working chamber can be metered.

The invention will be described in the following description of an embodiment in conjunction with the attached Drawing explained in more detail. In the drawing show:

Figure 1 shows the pneumatic control group of a brake booster according to the invention in longitudinal section, partially broken away, in the inactive ready position.

Fig. 2 is a perspective view of an assembly forming part of the pneumatic control valve of the brake booster according to the invention;

FIG. 3 shows the assembly according to FIG. 2 in an axial sectional view; FIG.

Fig. 4 shows an enlarged section in the region of the poppet valve of a known brake booster and

5 shows an enlarged detail in the region of the poppet valve of the brake booster according to the invention according to FIG. 1.

The only schematically indicated booster housing 1 of the brake booster according to the invention is divided by an axially movable wall 2 in a vacuum chamber 3 and a working chamber 4. The axially movable wall 2 consists of a deep-drawn sheet metal diaphragm plate 8 and a fitting flexible membrane 18, not shown in detail between the outer periphery of the diaphragm plate 8 and the booster housing 1 forms a rolling diaphragm as a seal.

A control valve 12 which can be actuated by an actuating rod 7 is guided in a sealed manner in the booster housing 1. th, the movable wall 2 supporting the control housing 5 housed and consists of a formed on the control housing 5 first sealing seat 15, a formed on one connected to the actuating rod 7 valve piston 9 second sealing seat 16 and a cooperating with two sealing seats 15,16, in a in Control housing 5 sealed immovably arranged guide member 21 guided, in cross-section L-shaped valve body 10 which is pressed by means of a, on the guide member 21 supporting the valve spring 22 against the valve seats 15,16. In this case, the valve body 10 has two coaxially formed sealing lips 13, 14 of different axial length, which cooperate with two coaxial cylindrical guide surfaces 26, 27 of the guide member 21. The guide member 21 defines a pneumatic chamber 17, which is acted upon by the valve body 10 formed in axial passages 19 with the pressure prevailing in the working chamber 4 pneumatic pressure. The working chamber 4 is connected to the vacuum chamber 3 via a laterally extending in the control housing 5 channel 28.

A return spring, not shown in the drawing, which is supported on the vacuum-side end wall of the booster housing 1, also not shown, holds the movable wall 2 in the starting position shown. In addition, a second compression spring or piston rod return spring 6 is provided which is supported on the one hand indirectly on the actuating rod 7 and on the other hand on the guide member 21 and whose force provides for a bias of the valve piston 9 and its sealing seat 16 relative to the valve body 10. In order to connect the working chamber 4 in the actuation of the control valve 12 with the atmosphere, finally, an approximately radially extending channel 29 is formed in the control housing 5. The return movement of the valve piston 9 at the end of a braking operation is limited by a cross member 11 which rests in the release position of the brake booster shown in the drawing on a formed in the booster housing 1 stop.

As can also be seen from the drawing, the stiffened by means of a metallic stiffening profile 41 valve body 10 has a cooperating with the two sealing seats 15,16 annular sealing surface 42 which is provided with a plurality of axial apertures 19. The flow channels formed by the passages 19 and openings in the sealing surface 42, not further denoted connect the pneumatic space 17 with a limited by the sealing seats 15,16 annular space, which is in communication with the above-mentioned pneumatic channel 29, so that on the the sealing surface 42 opposite side of the valve body 10 formed pneumatic space 17 is constantly in communication with the working chamber 4 and the valve body 10, a pneumatic pressure compensation takes place.

The described arrangement thus allows a reduction in the difference between the response of the brake booster and acting on the valve piston restoring force in the sense that at a constant response force, an increase in the restoring force or at a constant restoring force, a reduction of the response is possible, thereby improving the Hysteresis of the brake booster according to the invention is achieved.

In order to initiate an independent actuation of the brake booster according to the invention of the actuating rod 7, a third sealing seat 24 is provided radially between the first sealing seat 15 and the second sealing seat 16, which is actuated by means of an electromagnet 20, preferably in one, with the valve piston 9 fixedly connected housing 25 is arranged and therefore together with the valve piston 9 in the control housing 5 is displaceable. The electromagnet 20 comprises a coil 43 arranged inside the housing 25 and an axially displaceably arranged cylindrical armature 31, which is partially guided in a closure part 30 closing the housing 25 and on which a sleeve 32 is supported, in the area facing the valve body 10 the aforementioned third sealing seat 24 is formed. In the starting position of the armature 31 shown in the drawing, the third sealing seat 24 is axially offset relative to the second sealing seat 16 formed on the valve piston 9, so that between the third sealing seat 24 and the sealing surface 42 of the valve body 10, a gap is present. In addition, a preferably radially inside the sleeve 32 guided ring member 36 is provided, which is shown in particular in Figs. 2 and 3 and the interposition of a resilient or compressible member 37 is supported on the sleeve 32 such that between him and the sleeve 32 a relative movement is possible. The elastic or compressible element 37 is formed in the example shown by a corrugated spring and allows a controllable control of the ring member 36th A partial region of the ring element 36 facing the valve body 10 is subdivided into partial regions 33 by radial openings 38.

In order to connect a limited by the sleeve 32 and the ring member 36 in the control housing 5 pneumatic chamber 23 with the working chamber 4, an opening 34 is provided in the two parts mentioned, which is shown in FIGS. 2 and 3. The arrangement of the above-mentioned corrugated spring 37 in the installed state is preferably made such that it, seen in the operating direction of the control valve 12, behind the opening 34 and the aforementioned cross member 11 is located. As a result, the corrugated spring 37 is arranged outside the direct air flow region, whereby positive effects on the flow cross sections in terms of the dynamics and the noise behavior of

Brake booster can be achieved. In addition, the ring element 36 in its corrugated spring 37 facing region locking elements or projections 35 which cooperate with formed in the sleeve 32 recesses 39 together so that the ring member 36 forms a detachable assembly with the sleeve 32.

As is apparent from FIGS. 2 and 3, the ring member 36 at its end facing the valve body 10 in the region of the portions 33 a circumferential ring 47, which is provided integrally with the ring member 36 and the flush with the portions 33 in the direction Valve body 10 is formed. Furthermore, the circumferential ring 47 has the same inner diameter as the ring element 36 in the region of the partial regions 33. The production of the Ring element 36 with the molded circumferential ring 47 takes place, for example, in a simple and cost-effective manner by injection molding. The radial arrangement of the ring 47 with respect to the valve body 10 is shown in particular in FIG. It can be seen that the ring 47 is arranged with respect to the passages 19 of the valve body 10 such that the ring 47 covers the passages 19 at its radial inner side 48, but does not completely close the passages 19. As a result, the pressure equalization between the space 17 within the valve body 10 and the space 23 via the openings 38 of the ring member 36 and the opening 34 of the ring member 36 and the sleeve 32 is ensured. The function of the ring member 36 and the sleeve 32 and the advantages of the circumferential ring 47 will be described below in detail.

In the embodiment of the brake booster according to the invention shown in the drawing electrical switching means 40,44 are finally provided, which are particularly important in braking operations, in which in addition to the driver actuation of the solenoid 20 is driven to bring about regardless of the driver's will full braking (so-called brake assist function). It is of particular importance that the switching means 40,44 are operated at each braking. At the same time it must be ensured that the electromagnet 20 is switched off safely after completion of the power assisted braking operation. The switching means shown consist of a preferably on the valve piston 9 and the housing 25 of the electromagnet 20 attached, two switch positions having micro-switch 40 and one, the micro-switch 40 by a translational movement actuated actuator 44, the is sealingly guided in a provided in the control housing 5 bore and cooperates with a amplifier housing fixed stop 45, which carries the reference numeral 45 and may be formed for example by a radial collar of the rear amplifier housing half. Between the actuating element 44 and the control housing 5, a pressure spring 46 is arranged so that the microswitch 40 remote from the end of the actuating element 44 abuts under a bias on the stop 45.

The individual actuation phases of the control valve 12 in its external operation by the electromagnet 20 are basically known and are therefore described only briefly.

In the rest or standby position of the control valve 12 shown in FIG. 1, the valve body 10 abuts both the first sealing seat 15 and the second sealing seat 16, so that the two chambers 3,4 of the brake booster are separated from each other and the connection of the working chamber 4 is interrupted with the atmosphere. The third sealing seat 24 is located at a distance from the sealing surface 42 of the valve body 10 and the annular element rests with its partial regions 33 and the circumferential ring 47 on the sealing surface 42.

To control a pressure build-up position driver independent, the electromagnet 20 is energized, so that both the third sealing seat 24 and the ring member 36 at the same time compression of the elastic member 37 first come to rest on the valve body 10 and then the valve body 10 against the force of the valve spring 22 in move the drawing to the right, so that between the second sealing seat 16 and the valve body 10, a gap is formed and a ventilation of the working chamber 4 takes place. The first sealing seat 15 is replaced by the third sealing seat 24 functionally.

In a pressure holding phase, the second sealing seat 16 and the third sealing seat 24 are closed, so that no changes of the pressure prevailing in the booster housing 1 pneumatic pressure can occur.

In a controlled pressure reduction phase of the second sealing seat 16 remains closed and the third sealing seat 24 lifts from the sealing surface 42, while the ring member 36 abuts with its portions 33 and the circumferential ring 47 by the bias of the elastic member 37 to the sealing surface 42, so that About recesses 49 of at least a portion of the portions 33, which in particular from Fig. 2 can be seen, a metered suction of the atmosphere from the working chamber 4 and thus a reduction in the booster housing 1 of the pneumatic

Brake booster controlled pneumatic pressure takes place.

4 and 5, a normal braking is shown, in which the valve piston 9 is moved with the associated sealing seat 16 in the direction of actuation A by the actuating rod 7 and the first, formed on the control housing 5 sealing seat 15 remains closed. Thus, atmosphere can flow into the working chamber 4 via the opened second sealing seat 16, so that a differential pressure is built up in the booster housing 1. The general function of a brake booster is well known, so that a description in this respect is omitted.

4 shows a partial view of a known brake booster according to WO 2006/005742 A1 in longitudinal section. As can be seen, the passages 19 of the valve body 10 are overflowed when opening the second sealing seat 16 by an air flow, wherein the air flow is illustrated by the arrow L. The air flow L leads through the passages 19 of the valve body 10, thereby swirling and generates in the space 17 of the valve body 10, a vibrating air column 35, which generates a disturbing noise, since the space 17 acts as a resonator. Another cause of disturbing noises in a normal braking position may be an air envelope of the airflow L at edges of the sleeve 32.

In Fig. 5 the relevant area of the brake booster according to the invention according to FIGS. 1 to 3 is shown in an enlarged view. As can be seen, covers the voltage applied to the sealing surface 42 ring 47 of the ring member 36, the radial inner side 48 of the passages 19. This ensures that the air flow L along an inner side 50 of the ring member 30 is guided in the direction of working chamber 4, whereby the air flow L the passages 19 do not overflow and noise can be prevented. As a further advantage results in an improved management of the air flow L, which under certain circumstances, an improvement of the Ansprech- and the release time of the brake booster can be made possible.

LIST OF REFERENCE NUMBERS

1 amplifier housing

2 movable wall

3 vacuum chamber

4 working chambers

5 control housing

6 piston rod return spring

7 operating rod

8 diaphragm discs

9 valve piston

10 valve body

11 cross member

12 control valve

13 sealing lip

14 sealing lip

15 sealing seat

16 sealing seat

17 room

18 rolling diaphragm

19 passage

20 electromagnet

21 guide part

22 valve spring 23 space

24 sealing seat

25 housing

26 guide surface

27 guide surface

28 channel 29 channel

30 closure part 31 anchors

32 sleeve

33 subarea

34 breakthrough

35 locking element

36 ring element

37 element

38 breakthrough

39 recess

40 microswitches

41 stiffening profile

42 sealing surface

43 coil

44 actuator

45 stop

46 spring

47 ring

48 inside 49 recess 50 inside

A Actuation direction L Air flow

Claims

claims

1. brake booster for motor vehicles with an amplifier housing (1) whose interior is divided by a movable wall (2) in a vacuum chamber (3) and a working chamber (4), and with a movable wall (2) carrying the control housing (5) in which a control valve (12) is arranged, which controls a pneumatic pressure difference acting on the movable wall (2) and by an actuating rod (7) by means of a valve piston (9) as well as independent of the actuating rod (7) by an electromagnet (20) is actuated and consists of three concentrically arranged sealing seats (15, 16, 24) and one with the sealing seats (15, 16, 24) cooperating, with axial passages (19) provided valve body (10), wherein the first sealing seat (15) in the control housing (5) and the second sealing seat (16) on the valve piston (9) are formed, while the third sealing seat (24) on one, with the electromagnet (20) cooperating H sleeve (32) is formed, and wherein a relation to the third sealing seat (24) slidably disposed ring member (36) is provided, which is supported with the interposition of an elastic or compressible element (37) on the sleeve (32), of which the valve body (10) facing edge region by radial openings (38) separated from each other portions (33), via which it is in contact with the valve body (10), and which in the release position relative to the third sealing seat (24) to the valve body (10) out axially offset, wherein the ring member (36) radially within the sleeve (32) is arranged, that its sub-areas (33), over which he the valve body (10) is in contact, at least partially release the passages (19) provided in the valve body (10), characterized in that the ring element (36) comprises means for guiding an air flow (L) occurring during normal braking in the direction of the working chamber (4 ) having.

2. Brake booster according to claim 1, characterized in that the means allow a guide of the air flow (L) along an inner side (50) of the ring element (36).

3. Brake booster according to claim 2, characterized in that the ring element (36) at its, the valve body (10) facing the end of a circumferential ring (47) which is flush with the sub-areas (33) in the axial direction, wherein the ring (47) covers a radial inner side (48) of the passages (19) in the radial direction.

4. Brake booster according to claim 3, characterized in that the ring (47) is integrally provided connected to the partial areas (33) of the ring element (36).

5. brake booster according to claim 4, characterized in that the ring element (36) with the ring

(47) is provided as a one-piece injection molded part.

6. Brake booster according to one of claims 1 to 5, characterized in that the regions (33) of the ring element (36) have a greater wall thickness, wherein at least a portion of the portions (33) with the valve body (10) facing recesses (49) is.