WO1998033688A1

WO1998033688A1 - Pressure control valve

Info

Publication number: WO1998033688A1
Application number: PCT/EP1998/000444
Authority: WO
Inventors: Johann Jungbecker; Manfred Rüffer
Original assignee: Itt Manufacturing Enterprises, Inc.
Priority date: 1997-02-01
Filing date: 1998-01-28
Publication date: 1998-08-06
Also published as: DE19703775A1

Abstract

An electromagnetically controllable multiple way control valve for hydraulic, anti-lock motor vehicle brake systems puts at least one wheel brake (wheel) in hydraulic communication with a high-pressure source (THZ) or a low-pressure reservoir (NDS) and comprises a slide (6) guided in a cylindrical housing body (2) prestressed in both directions in the longitudinal direction of displacement (4), as well as an elongate opening (33) in the longitudinal direction. During normal operation of the brakes, the slide is prestressed towards a first end position in which the wheel brake is in fluid communication with the high-pressure source and cut off from the low-pressure reservoir. A valve (60) provided between the wheel brake and the low-pressure reservoir is opened to reduce pressure in the wheel brake. To prevent the slide (6) from getting stuck during normal brake operation, the multiple way control valve has a longitudinally movable pressure piston (48) arranged in the opening (33) of the slide (6). During normal brake operation, the pressure piston (48) acts with its free end (50) against the force that prestresses the slide towards the first end position, so that the slide (6) can move back and forth in the longitudinal direction depending on the pressure of the high-pressure source.

Description

Pressure control valve

The invention relates to an electromagnetically controllable multi-way control valve for slip-controlled hydraulic motor vehicle brake systems for establishing a pressure medium connection between at least one wheel brake and a high-pressure source or a low-pressure accumulator, comprising a slide guided in a sleeve-shaped housing body, which is biased in the longitudinal direction of displacement and one extending in the longitudinal direction Opening, wherein in normal braking operation the bias towards a first end position dominates, in which the wheel brake is fluidly connected to the high-pressure source and is fluidly separated from the low-pressure accumulator, and a valve provided between the wheel brake and the low-pressure accumulator, which is used to reduce pressure in the wheel brake is opened.

Such a multi-way valve is known for example from DE 44 41 150 AI. The is in normal braking mode Slider in such a position that a radial opening in the sleeve-shaped housing body, which forms a connection for the high-pressure source, is in pressure medium connection with another opening located in the region of the slide end, which forms a connection for a wheel brake. The slide is designed as a hollow slide, so that the fluid connection of the high pressure source and the wheel brake leads through the longitudinal opening of the slide. If measured wheel sensors of the electrical control and regulating unit of a slip-controlled motor vehicle brake system determine that the wheel is locked, an electromagnetic actuator is energized so that an armature of the electromagnetic actuator is moved in the longitudinal direction of the slide. The armature acts on the slide via a push rod and adjusts it in such a way that the pressure medium connection between the high pressure source and the wheel brake is interrupted. Then the plunger which engages through the slide strikes against a spherical valve closing member and lifts it off its sealing seat, whereby a pressure medium connection between the wheel brake and the low-pressure accumulator is opened to reduce the pressure in the wheel brake.

In multi-way valves of the type mentioned at the beginning, as well as in the multi-way valve described above, the slide remains in the above-described position in normal braking operation. Because sometimes it takes a very long time can, until the normal brake operation is exited via the control or regulating device of the brake system and the wheel brake is to be connected to the low-pressure accumulator in order to reduce the pressure, there is sometimes the risk that the slide sticks in its normal brake position, so that rapid pressure reduction in the wheel brake does not occur can be achieved without delay in the desired manner.

The above invention is therefore based on the object of eliminating the risk of the slide sticking in its normal braking position for a multi-way pressure control valve of the type described in the introduction.

This object is achieved in a multi-way pressure control valve of the type mentioned according to the invention in that a slowly displaceable pressure piston is provided in the opening of the slide, which counteracts the bias directed into the first end position with its free end in normal braking operation, so that the slide depends on Pressure of the high pressure source is reciprocable in the longitudinal direction.

When the control pressure of the high-pressure source builds up, the pressure piston, which is displaceable in the longitudinal opening, is displaced with ever increasing force in the direction of the mouth of the opening and can thus counteract the preload directed in the direction of the first end position, so that the slide is moved slightly counter to the preload, for that to apply the appropriate equilibrium position. If the control pressure is reduced, the spool is slightly moved back under the effect of the preload. According to the invention, a slight back and forth movement of the slide is achieved in normal braking operation, so that there is no risk that the slide will become stuck.

In a preferred embodiment of the invention, the bias in the direction of the first end position is transmitted from a spring means via a mediator element to the slide, and the pressure piston which is longitudinally displaceable in the slide opening is supported against the mediator element. With increasing control pressure in the longitudinal opening of the slide, the pressure piston now presses with increasing force against the mediator element, so that the slide with the mediator element moves against the force of the spring means.

Preferably, the mediator element is formed by an armature of an electromagnetic actuating device, which in the de-energized state of the actuating device, i. H. in normal braking operation, is biased towards an end position.

To exit normal braking operation - if the pressure is in the wheel brake is to be removed - the bias of the slide directed towards the first end position is removed, for example by moving an anchor via the electromagnetic actuating device, so that the slide closes the pressure medium connection between the high-pressure source and the wheel brake and between the wheel brake and low-pressure accumulator opens Position is shifted.

In a particularly advantageous embodiment of the multi-way valve according to the invention, the longitudinal opening of the slide opens at its end facing away from the pressure piston on the end face of the slide there, and in the mouth region of the opening, a pin which moves to a limited extent engages, which connects the valve mentioned above between the wheel brake and Low pressure accumulator keeps closed during normal braking. Due to the limited longitudinal displaceability of the pin, the valve remains closed in normal braking operation even when the slide is moved back and forth in the inventive manner described above.

The longitudinally displaceable pin is biased in the closing direction of the valve in normal braking operation by the pressure of the high-pressure source in the opening and is supported against the housing body via the valve.

The valve is preferably between the wheel brake and Low-pressure accumulator designed as a seat valve and the valve body of the seat valve can be actuated from the free end of the longitudinally displaceable pin which projects from the longitudinal opening. In a very particularly advantageous manner, the free end of the longitudinally displaceable pin itself forms the valve body of the seat valve and, in normal braking operation, lies sealingly against a sealing seat of the seat valve. For this purpose, the free end of the longitudinally displaceable pin is designed in the form of a sealing pin.

The longitudinal displaceability of the pin could in any way be limited in order to prevent the pin from sliding out of the longitudinal opening of the slide. In terms of production technology, however, it has proven to be particularly simple and therefore advantageous if the pin has a radial projection which can be placed against a stop to limit the longitudinal displacement. The projection is preferably arranged such that it comes to lie outside the opening. The stop which is also to be provided in this case outside the opening can then be achieved in a technically simple manner by a cup-shaped element placed against the end face of the slide, which has a bottom opening through which the pin slidably engages, but which are not passed by the radial projection of the pin can.

According to a further particularly preferred embodiment of the Invention is provided in the interior of the longitudinal opening of the slide, a longitudinally displaceable piston-like pressure transmission part bearing against the inwardly facing end face of the longitudinally displaceable pin. As a result, the sealing effect of the pin which is longitudinally displaceable in the opening can be improved.

Further features, details and advantages of the invention result from the appended protection claims and the drawing and the following description of a preferred embodiment of the multi-way pressure control valve according to the invention. In the drawing, the figure shows a longitudinal section through an inventive multi-way pressure control valve in the normal braking position.

The multi-way pressure control valve shown in longitudinal section in the figure comprises a sleeve-shaped housing body 2 and a slide 6 which is displaceable therein in the longitudinal direction 4. The slide 6 is prestressed in the longitudinal direction 4 in opposite directions, namely in the direction of the first end position shown by a first spring 8 and in the opposite direction by a second spring 10. The first spring 8 is supported at one end against a core 12 and at the other end against an armature 14 of an electromagnetic actuating device 16. The armature 14 bears with its side facing away from the spring 8 against an end face 18 of the slide 6. The core 12 of the electromagnetic actuator 16 is held in a press fit by means of a pot-shaped holding element 20, which is placed over a free end 22 of the sleeve-shaped housing body 2 and is sealed off from it. A coil holder 24 with a coil 26 of the electromagnetic actuating device 16 is arranged on the circumference of the cup-shaped element 20. In the energized state, the armature 14, which is displaceable in the longitudinal direction 4 within the cylindrical end section 22 of the housing body 2, is moved against the core 12 against the bias by the spring 8.

Provided in the sleeve-shaped housing body 2 in the longitudinal direction 4 are openings 28, 30, 32 which are spaced apart in the radial direction and form a pressure medium connection to a low-pressure accumulator, a wheel brake or a high-pressure source in the form of a tandem master cylinder. The slide 6 is designed as a hollow slide and has an inner opening 33 which extends in the longitudinal direction 4. The slide 6 has on its outer circumference a first control edge 34 which interacts with a corresponding control edge 36 of the sleeve-shaped housing body 2 and thereby releases or closes a variable throttle cross section 38 between the connection 32 for the high pressure source and the inner longitudinal opening 33 of the slide 6. The control edge 34 delimits an annular groove 40, which is provided concentrically in the outer peripheral surface of the slide 6. The groove 40 communicates via two radial bores 42 with the inner longitudinal opening 33 of the Slide 6.

In the normal braking position shown, there is a likewise concentric annular groove 44 in the region of the pressure medium connection 30 to the wheel brake. Two inclined bores 46 connect the groove 44 to the inner longitudinal opening 33 of the slide 6. There is therefore a pressure medium connection between the high pressure source and the wheel brake.

At the armature-side end of the slide 6, a slowly displaceable pressure piston 48 is provided in the inner longitudinal opening 33, which is acted upon at one end by the pressure of the high-pressure source prevailing in the inner longitudinal opening 33 and at the other end - like the slide 6 - with its end face 50 against the armature 14 supports.

At the end of the slide 6 facing away from the armature 14, a slowly displaceable pin 52 engages from the outside in the inner longitudinal opening 33 of the slide 6. The pin 52 has at its free end 54 a sealing pin 56 which, in the illustrated normal braking position, bears against a sealing seat 58 of a seat valve 60 which closes the pressure medium connection 28 of the low-pressure accumulator. The pin 52 has a radial collar 62 located outside the longitudinal opening 33. A spiral spring 64 surrounding the pin 52 is supported at one end against this collar 62 and at the other end against the end face 66 of the slide 6, so that the pin 52 in Direction is biased to the sealing seat 58. Spring 64 and collar 62 are located within a cup-shaped element 68, which rests with a collar-shaped flange section 70 against the end face 66 of the slide 6 and has a bottom opening 72 through which the pin extends so as to be longitudinally displaceable. The bottom region 74 of the cup-shaped element 68 forms a stop 76 for the radial collar 62 of the pin 52 and therefore forms a displacement end position for the pin 52.

In the inner longitudinal opening 33 there is further provided a slowly displaceable pressure and sealing piston 78 which is acted upon at one end by the pressure prevailing in the inner opening 33 and at the other end abuts against the end 80 of the pin 52 which engages in the longitudinal opening 33.

The illustrated multi-way pressure regulating valve works as follows: In the drawing of the figure, the armature 14 and thus the slide 6 are under the pretension of the spring 8 in their first end position. There is a pressure medium connection between the connection 32 of the high-pressure source and the connection 30 of the wheel brake, in which the variable throttle cross-section 38 is opened to a maximum in the area of the connection 32, so that pressure medium via the annular groove 40, the transverse bores 42 into the inner longitudinal opening 33 and over the inclined holes 46 to the annular groove 44 and Pressure medium connection 30 of the wheel brake can reach. With increasing control pressure via the pressure medium connection 32, the pressure piston 48 presses with its end face 50 with a correspondingly greater force against the armature 14, so that the force of the spring 10 plus the force of the pressure piston 48 is slightly greater than the opposite force of the spring 8. Slide 6 The pressure piston 48 and armature 14 will therefore move slightly to the right against the force of the spring 8 until an equilibrium of forces is reached again. If the control pressure present via the connection 32 is increased further, the slide 6 together with the pressure piston 48 and armature 14 are moved further to the right. When the control pressure decreases, slide 6, pressure piston 48 and armature 14 will again move to the left. The slider 6 is therefore constantly moved back and forth in normal braking operation in accordance with the control pressure present, thereby eliminating the risk that the slider will get stuck. During the back and forth movement of the slide 6 in normal braking operation, the pressure and sealing piston 78 is also moved back and forth under the effect of the control pressure and holds the sealing pin 56 of the pin 52 in sealing contact with the sealing seat 58 by pressing on the pin 52 Seat valve 60. The pin 52 is therefore supported on the sealing seat 58.

If normal braking operation is now to be exited when the brake pressure is applied because the locking of a wheel has been determined by the control and regulating device of the brake system, then the electromagnetic actuating device 16 energized and the armature 14 moves in the direction of the core 12 and in this ABS case, the forces between armature 14 and core 12 determine the position into which the slide 6 is pushed under the action of the spring 10. During this displacement, the control edge 34 of the slide 6 first passes over the corresponding control edge 36 of the housing body 2, so that the pressure medium connection between the inner slide opening 33 and the high-pressure source is separated. In the meantime, the pin 52 is moved out of the inner longitudinal opening 33 of the slide 6 until its radial collar 62 abuts against the stop 76. The sealing pin 56 is then lifted off the sealing seat 58, so that the seat valve 60 opens to the pressure medium connection 28 of the low-pressure accumulator. Finally, a control edge 82, which is formed by the end face 66 of the slide 6, passes over a corresponding control edge 84 of the housing body 2, whereby a throttle cross-section, not shown in the figure but easily imaginable, is opened between the pressure medium connection 30 of the wheel brake and the opened seat valve 60 to cause a pressure reduction in the wheel brake to the low pressure accumulator.

To maintain pressure, the control edge 82 of the slide 6 passes over the control edge 84 in the opposite direction, so that the throttle cross section between the wheel brake and the low-pressure accumulator is interrupted again, the seat valve 60 still remaining open. If the pressure in the wheel brake is to be increased again, the current in is controlled accordingly the coil 26, the armature 14 is moved so far to the left under the action of the spring 8 until the control edge 34 of the slide opens the control edge 36 again in the region of the pressure medium connection 32 to the high pressure source.

In this activated ABS control position, the sealing and pressure piston 78 is supported on the housing via the pin 52, the collar 62, the stop 64, the collar 70 and the spring 10.

Claims

claims

1. Electromagnetically controllable multi-way control valve for slip-controlled hydraulic motor vehicle brake systems, for establishing a pressure medium connection between at least one wheel brake (wheel) and a high pressure source (THZ) or a low pressure accumulator (NDS), comprising

a slide (6) which is guided in a sleeve-shaped housing body (2) and which

The longitudinal direction of displacement (4) is biased in both directions and has an opening (33) running in the longitudinal direction, the bias predominating towards a first end position in normal braking operation, in which the wheel brake is fluidly connected to the high-pressure source and is fluidly separated from the low-pressure accumulator, and

one between the wheel brake and the

Low-pressure accumulator provided valve (60), which is opened to reduce pressure in the wheel brake,

characterized,

that in the opening (33) of the slide (6) a slowly displaceable pressure piston (48) is provided, which in normal braking operation with its free end (50) in the first end position counteracts bias, so that the slide (6) can be moved in the longitudinal direction depending on the pressure of the high pressure source.

!. Multi-way control valve according to claim 1, characterized in that the bias towards the first end position is transmitted from a spring means (8) via a mediator element to the slide (6) and the longitudinally displaceable pressure piston (48) is supported against the mediator element.

). Multi-way control valve according to claim 2, characterized in that the mediator element is formed by the armature (14) of an electromagnetic actuating device (16).

1. Multi-way control valve according to claim 1, 2 or 3, characterized in that the longitudinal opening (33) of the slide (6) at its end facing away from the pressure piston (48) on the end face (66) of the slide (6 ) opens and that in the mouth area of the opening (33) engages a pin (52) which can be moved slowly and which keeps the valve (60) between the wheel brake and the low-pressure accumulator closed in normal braking mode. Multi-way control valve according to claim 4, characterized in that the longitudinally displaceable pin (52) is biased in the closing direction of the valve (60) by the pressure of the high pressure source present in the opening (33).

>. Multi-way control valve according to claim 5, characterized in that the valve (60) between the wheel brake and low-pressure accumulator is designed as a seat valve and that the valve body of the seat valve can be actuated by the free end (54) of the longitudinally displaceable pin (52) which projects from the longitudinal opening.

1 . Multi-way control valve according to claim 5, characterized in that the valve (60) between the wheel brake and the low pressure accumulator is designed as a seat valve and the free end (54) of the longitudinally displaceable pin (52) forms the valve body of the seat valve and in normal braking operation against a sealing seat (58 ) of the seat valve lies tight.

Multi-way control valve according to one of claims 5-7, characterized in that the longitudinally displaceable pin (52) has a radial projection (62) which can be placed against a stop (76) to limit the longitudinal displaceability.

9. Multi-way control valve according to claim 8, characterized in that the radial projection (62) of the pin (52) and the stop (76) cooperating therewith are arranged outside the slide (6).

10. Multi-way control valve according to one of claims 5-9, characterized in that in the interior of the opening (33) against the end face (66) of the pin (52) adjacent longitudinally displaceable pressure transmission part (78) is provided.

11. Multi-way control valve according to at least one of the preceding claims, characterized in that the slide (6) has a first control edge (34) and together with a corresponding control edge (36) on the housing body (2) a first variable throttle cross-section (38) in the hydraulic pressure medium connection between the high pressure source and the wheel brake.

12. Multi-way control valve according to at least one of the preceding claims, characterized in that the slide (6) has a second control edge (82) which with a corresponding second control edge (84) on the housing body (2) has a second variable throttle cross section in the hydraulic pressure medium connection between wheel brake and Low pressure accumulator forms.

13. Multi-way control valve according to claims 12 and 13, characterized in that the first (34, 36) and second (82, 84) control edges are arranged such that when the slide (6) is moved in the direction of a pressure reduction on the wheel brake first the first flow cross section (38) is closed and only then is the second flow cross section opened.