GB2197404A - Hydraulic brake system comprising a brake and traction slip control device - Google Patents

Hydraulic brake system comprising a brake and traction slip control device Download PDF

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Publication number
GB2197404A
GB2197404A GB08725509A GB8725509A GB2197404A GB 2197404 A GB2197404 A GB 2197404A GB 08725509 A GB08725509 A GB 08725509A GB 8725509 A GB8725509 A GB 8725509A GB 2197404 A GB2197404 A GB 2197404A
Authority
GB
United Kingdom
Prior art keywords
pressure
chamber
piston
valve
brake
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08725509A
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GB2197404B (en
GB8725509D0 (en
Inventor
Norbert Ocvirk
Joachin Maas
Adolf Leinhaeuser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Teves AG and Co oHG
Original Assignee
Alfred Teves GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alfred Teves GmbH filed Critical Alfred Teves GmbH
Publication of GB8725509D0 publication Critical patent/GB8725509D0/en
Publication of GB2197404A publication Critical patent/GB2197404A/en
Application granted granted Critical
Publication of GB2197404B publication Critical patent/GB2197404B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/44—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition co-operating with a power-assist booster means associated with a master cylinder for controlling the release and reapplication of brake pressure through an interaction with the power assist device, i.e. open systems
    • B60T8/446—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition co-operating with a power-assist booster means associated with a master cylinder for controlling the release and reapplication of brake pressure through an interaction with the power assist device, i.e. open systems replenishing the released brake fluid volume via the master cylinder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
    • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
    • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
    • B60T8/4836—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems wherein a booster output pressure is used for normal or anti lock braking

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Regulating Braking Force (AREA)

Abstract

A hydraulic brake system comprising a brake and traction slip control wherein, in the event of a slip control, the wheel brake cylinders will be connected to a pressure source (17), a pressure-reducing valve (32) being switched into that connection. The control chamber (40) of the pressure-reducing valve (32) is confined by the valve piston (33) and a control piston (45) to which spring force is applied, and is in communication with the booster chamber (15). In the event of a brake slip control, a pressure corresponding to the pressure in the booster chamber (15) is made available to the wheel brakes, whereas in the event of a traction slip control, the reduced accumulator pressure is supplied to the wheel brakes. <IMAGE>

Description

SPECIFICATION Hydraulic brake system comprising a brake and traction slip control device This invention relates to a hydraulic brake system comprising a brake and traction slip control device for use with an automotive vehicle, which is provided with a pedal-operated brake pressure generator composed of a master brake cylinder, a force booster and a pressure source, together with valves associated with the wheel brakes, the valves being driven by a slip control device.
DE-OS 3338826.1 discloses a brake system comprising a slip control wherein at least the wheel cylinders of the driven wheels are in communication with the working chambers of the master brake cylinder, and the working chambers, through a plenum chamber, in the case of a brake slip control, are in communication with the booster chamber, and in case of a traction skid control, are in direct communication with the pressure source.
To ensure a pressure supply of the aforementioned type, a combination of three 2way/2-position valves is provided (e.g. Figure 4 of the Offenlegungsschrift referred to). The expenditure in terms of valves is therefore substantial and there is the risk that, in the event of a failure of a valve, no adequate pressure fluid will be available for skid control.
It is, therefore, an object of the present invention to reduce the expenditure in terms of valves.
Moreover, in the event of a traction slip control, a brake pressure is to be made available which is independent of potentially existing pressure fluctuations of the pressure source. This goal is equally intended to be achieved with no additional efforts in terms of valves.
According to the invention, there is provided a hydraulic brake system comprising a brake and traction slip control device for use with an automotive vehicle, which is provided with a pedal-operated brake pressure generator composed of a master brake cylinder, a force booster and a pressure source, together with valves associated with the wheel brakes, the valves being driven by a slip control device, characterised in that coupled behind the pressure source is a pressure-reducing valve driven either by the pressure prevailing in the booster chamber or-if the pressure in the booster chamber becomes low-by a predetermined force such that the pressure prevailing in an outlet chamber of the pressure-reducing valve corresponds either to the pressure of the booster chamber or to a pressure equivalent to the predetermined force.
The pressure-reducing valve is, in an embodiment of the invention, advantageously, of a configuration such that a control chamber of the pressure-reducing valve, on one side thereof, is confined by a valve piston and, on the other side thereof is confined by a control piston, a predetermined force e.g. a spring force, being applied to the side of the control piston facing away from the control chamber.
In order to enable the control piston to act upon the valve piston if no pressure or only a low pressure prevails in the control chamber, the control piston can, via a plunger, be placed into abutment with the valve piston thereby to enable, for example, the spring forces to act upon the valve piston.
To ensure, in the case of the lowest possible pressures in the control chamber, that the control piston is forced away from the valve piston, the front face of the control piston can be larger than the front face of the valve piston.
Advantageously, the valve piston is composed of a guide piston and a valve cone the tapering side of which is in communication with the guide piston and the surface of which is capable of being placed into abutment with a packing seat.
It is also advantageous if the base of the valve cone protrudes into the outlet chamber and the tapering part of the valve cone together with the guide piston confines the inlet chamber.
For leak testing the gaskets of the valve piston, it is desirable that the smaller step pf a stepped piston is capable of being placed into abutment with the valve piston, the larger step thereof bordering on the control chamber and a chamber formed by the stepped piston being in communication with the non-pressurised reservoir.
To safeguard a pressure supply at least to the driven wheels in the event of a skid control, it can be provided that at least the wheel brake cylinders of the driven wheels are in communication with working chambers of the master brake cylinder, the working chambers being in communication with the pressure-reducing valve through a plenum chamber and a master valve opening in the event of a brake or traction skid control.
For this purpose, advantageously, the master valve is in communication with the outlet chamber of the pressure-reducing valve, an inlet chamber being connected to the pressure source and the control chamber being connected to the booster chamber.
An embodiment of the invention will now be described by way of example with reference to the single Figure of the accompanying drawing.
The Figure is a sectional view of a brake master cylinder, of a booster coupled ahead thereof of an associated pressure-reducing valve and the incorporation thereof into a brake system.
The brake pressure generator comprises a master brake cylinder 1 in the bore 2 of which are guided two pistons 3 and 4 thereby forming two working chambers 5 and 6.
Coupled ahead of working chambers 5 and 6 is a plenum chamber 7 which, through central valves 8,9 and sleeve sealants 10,11 in the form of check valves, are in communication with the working chambers.
Coupled ahead of the brake master cylinder 1 is a brake force booster 12. A booster piston 13 is guided in a bore 14, confining, with the side thereof facing away from the master brake cylinder, a booster chamber 15.
The booster chamber 15, through a pressure control means 16, is in communication with the pressure source 17 substantially composed of a pump 18 and an accumulator 19.
The front wheel brakes, through pressure conduits 20,21, are in communication with the working chambers 5,6 of the master brake cylinder, the normally open magnetic valve 22,23 being switched into the pressure conduit. The rear wheel brake cylinders, through line 24, are in communication with the booster chamber, a normally open valve 25 being switched into the line.
The wheel brake cylinders, through the normally closed magnetic valves 26,27,28, are connected to the compensating reservoir 29.
The plenum chamber 7, through the master valve 30, is connected either to the compensating reservoir 29 or to the outlet chamber 31 of a pressure-reducing valve 32.
The pressure-reducing valve 32 comprises a valve piston 33 composed of a valve cone 34 and a guiding piston 35. The guiding piston 35 is sealingly guided in a bore 36 of the valve housing 37. The cone surface 38 can be sealingly placed into abutment with a packing seat 39. Formed betweeen the guiding piston 35 and the cone surface 38 is the inlet chamber 40 of the controllable pressure-reducing valve 32. The inlet chamber 40 is in direct communication with the accumulator 19.
The base surface of the cone protrudes into the outlet chamber 31 which-as already explained is in communication with the master valve 30.
Coupled to the guiding piston 35 is first a stepped piston 41 around which is formed a space 42 which is in communication with the compensating reservoir 29.
The stepped piston 41 borders on the control chamber 43 which is located in another bore section 44 of the housing 37 and is confined by the control piston 45. The control chamber 43 is in communication with the booster chamber 15 of the force booster 12.
The control piston 45, by means of a plunger 46 and the stepped piston 41, acts upon the valve body 33. Force is applied to the control piston 45 by a spring 47 supported on the bottom of the housing.
The brake system and the pressure-reducing valve operate as follows: In the event of a deceleration in which a skid control is not yet required, a pressure is built up in the booster chamber 15 through the brake pressure control system 16 which, through booster piston 13, acts upon pistons 3 and 4, involving a pressure build-up in the working chambers 5 and 6.
The pressure in the working chamber 5,6 and in the booster chamber 15, through the open valves 22,23,25 is transferred to the wheel brake cylinders.
At the same time, this pressure also develops in the control chamber 43 of the reducing valve 32 since this chamber is in communication with the booster chamber 15. The control piston 45 is thereby forced away against the force of spring 47 from the stepped piston 41 and, hence, from the valve piston 33.
Consequently, the pressure from the booster chamber 15 is applied to the valve piston only in accordance with the cross-sectional surface of the bore 36, thereby causing the valve piston 33 with the surface 38 thereof to be removed from the valve seat 39 to the extent that a pressure corresponding to the pressure in the booster chamber is built up in the outlet chamber 31. That pressure is led to the master valve 30 which is in its closing position, interconnecting the plenum chamber 7 and the compensating reservoir 29.
In case of imminent locking, for example, of the lefthand front wheel, this tendency is recorded by a sensor (not shown), whereupon a skid control device (not shown either) switches valve 22 into its blocking position and valve 20 into its open position thereby enabling pressure fluid to flow from the wheel brake cylinder to the compensating reservoir 29 to cause a pressure release in the wheel brake cylinder. This will re-accelerate the wheel and preclude the wheel from locking.
To re-decelerate the wheel, valves 20,22 reswitch to their initial position such that pressure is again applied to the wheel brake cylinders. For compensating the pressure fluid loss, it will be necessary to connect the wheel brake cylinders directly to the pressure source.
This is done in that the master valve 30 reswitches such that pressure fluid now flows from the accumulator 19 through the pressurereducing valve 32 of the plenum chamber 7 and the sealing sleeves 10,11 and the master valves 8,9, respectively, into the working chambers 5,6. The pressure to which the pressure fluid is exposed is determined by the reducing valve and the pressure of the booster chamber 1 5 supplied thereto.
In the event of a traction slip control, the mode of operation of the system is as follows: As the brake is not applied, no pressure is built up in the booster chamber 15 and, hence, in the control chamber 43 of the pressure-reducing valve 32. The piston 45 is displaced by the force of spring 47 to come, with the plunger 46 thereof, into abutment with the stepped piston 41. The latter trans fers the spring forces to the valve piston 33.
A pressure corresponding to the spring force is, therefore, built up in the outlet chamber.
If the skid control device now detects that, for example, the lefthand front wheel is tending to race, first, valves 22,26 reswitch and master valve 30 opens so that the reduced accumulator pressure, through plenum chamber 7, in the afore-described manner is passed into the working chambers 5,6. By switching back the valve 22, the reduced accumulator pressure is fed into the wheel brake cylinder of the lefthand front wheel. By closing and opening of the valves 22,26, the lefthand front wheel is always decelerated to such a degree that racing of the wheel is just avoided.
With the aid of the pressure-reducing valve 32 it is thus attained that, in the event of a brake skid control, a pressure corresponding to the pressure in the booster chamber 15 is made available to the wheel brakes, whereas in the event of a traction slip control, the reduced accumulator pressure is supplied to the wheel brakes.

Claims (10)

1. A hydraulic brake system comprising a brake and traction slip control device for use with an automotive vehicle, which is provided with a pedal-operated brake pressure generator composed of a master brake cylinder, a force booster and a pressure source, together with valves associated with the wheel brakes, the valves being driven by a slip control device, characterised in that coupled behind the pressure source (17) is a pressure-reducing valve (32) driven either by the pressure prevailing in the booster chamber (15) or-if the pressure in the booster chamber (15) becomes low-by a predetermined force such that the pressure prevailing in an outlet chamber (31) of the pressure-reducing valve (32) corresponds either to the pressure of the booster chamber (15) or to a pressure equivalent to the predetermined force.
2. A brake system as claimed in claim 1, characterised in that a control chamber (43) of the pressure-reducing valve (32), on one side thereof, is confined by a valve piston (33) and, on the other side thereof, is confined by a control piston (45), a predetermined force, for example, a spring force, being applied to the side of the control piston (45) facing away from the control chamber.
3. A brake system according to claim 2, characterised in that the control piston (45), via a plunger (46), can be placed into abutment with the valve piston (33).
4. A brake system according to claims 2 or 3, characterised in that the front face of the control piston (45) is larger than the front face of the valve piston (33).
5. A brake system according to any one of claims 2 to 4, characterised in that the valve piston (33) is composed of a guide piston (35) and a valve cone (33) the tapering side of which is in communication with the guide piston and the surface (38) of which is capable of being placed into abutment with a packing seat (39).
6. A brake system according to claim 5, characterised in that the base of the valve cone (33) protrudes into the outlet chamber (31) and the tapering part of the valve cone (33) together with the guide piston (35) confines the inlet chamber (40).
7. A brake system according to any one of claims 2 to 6, characterised in that the smaller step of a stepped piston (41) is capable of being placed into abutment with the valve piston (33), the larger step thereof bordering on the control chamber (43), and a chamber (42) formed by the stepped piston (41) being in communication with the non-pressurised reservoir (29).
8. A brake system according to claim 1, characterised in that at least the wheel brake cylinders of the driven wheels are in communication with working chambers (5,6) of the master brake cylinder, the working chambers being in communication with the pressure-reducing valve (32) through a plenum chamber (7) and a master valve (30) opening in the event of a brake or traction skid control.
9. A brake system according to claims 8 and 6 or 8 and 7, characterised in that the master valve (30) is in communication with the outlet chamber (31) of the pressure-reducing valve (32), an inlet chamber (40) being connected to the pressure source (17) and the control chamber (43) being connected to the booster chamber (15).
10. A hydraulic brake system substantially as described with reference to the accompanying drawings.
GB8725509A 1986-11-07 1987-10-30 Hydraulic brake system comprising a brake and traction slip control device Expired - Lifetime GB2197404B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19863638047 DE3638047A1 (en) 1986-11-07 1986-11-07 HYDRAULIC BRAKE SYSTEM WITH A BRAKE AND DRIVE SLIP CONTROL

Publications (3)

Publication Number Publication Date
GB8725509D0 GB8725509D0 (en) 1987-12-02
GB2197404A true GB2197404A (en) 1988-05-18
GB2197404B GB2197404B (en) 1990-10-31

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8725509A Expired - Lifetime GB2197404B (en) 1986-11-07 1987-10-30 Hydraulic brake system comprising a brake and traction slip control device

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JP (1) JPS63125460A (en)
DE (1) DE3638047A1 (en)
FR (1) FR2606348B1 (en)
GB (1) GB2197404B (en)
IT (1) IT1228938B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2622855A1 (en) * 1987-11-05 1989-05-12 Teves Gmbh Alfred BRAKE PRESSURE REGULATOR FOR ANTI-LOCK CONTROL AND TRACTOR SLIDE REGULATION

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3814404A1 (en) * 1988-04-28 1989-11-09 Teves Gmbh Alfred Brake system with antilock and traction control for motor vehicles
DE3910285C2 (en) * 1989-03-30 1996-12-19 Teves Gmbh Alfred Hydraulic brake system for motor vehicles with a device for regulating the drive slip

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2178499A (en) * 1985-07-30 1987-02-11 Teves Gmbh Alfred Brake system with both braking and traction slip control

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3338826A1 (en) * 1983-10-26 1985-05-09 Alfred Teves Gmbh, 6000 Frankfurt Brake system with slip control for motor vehicles
US4641895A (en) * 1983-10-26 1987-02-10 Itt Industries Inc. Brake system with slip control for automotive vehicles

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2178499A (en) * 1985-07-30 1987-02-11 Teves Gmbh Alfred Brake system with both braking and traction slip control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2622855A1 (en) * 1987-11-05 1989-05-12 Teves Gmbh Alfred BRAKE PRESSURE REGULATOR FOR ANTI-LOCK CONTROL AND TRACTOR SLIDE REGULATION

Also Published As

Publication number Publication date
IT1228938B (en) 1991-07-10
FR2606348B1 (en) 1990-06-01
FR2606348A1 (en) 1988-05-13
JPS63125460A (en) 1988-05-28
DE3638047A1 (en) 1988-05-11
GB2197404B (en) 1990-10-31
IT8721716A0 (en) 1987-08-26
GB8725509D0 (en) 1987-12-02

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19951030