GB2176855A - Anti-slip hydraulic brake system - Google Patents
Anti-slip hydraulic brake system Download PDFInfo
- Publication number
- GB2176855A GB2176855A GB08614205A GB8614205A GB2176855A GB 2176855 A GB2176855 A GB 2176855A GB 08614205 A GB08614205 A GB 08614205A GB 8614205 A GB8614205 A GB 8614205A GB 2176855 A GB2176855 A GB 2176855A
- Authority
- GB
- United Kingdom
- Prior art keywords
- chamber
- booster
- valve
- brake
- way valve
- 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
Links
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
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
Landscapes
- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Braking Systems And Boosters (AREA)
- Regulating Braking Force (AREA)
Abstract
An hydraulic brake system, in particular for automotive vehicles, with booster (2) a master cylinder being actuatable by a hydraulic power booster (2) and comprising at least one working chamber (19), connected to brake actuating members (20) and with apparatus for the limitation of the travel of a brake pedal (16) which controls a valve (15) by servo pressure medium is supplyable to said working chamber (19). Particularly in the interest of a reduction of the overall length and of a simplification of the apparatus, a 3/3-way valve (14), controlled by the axial position of stepped portion (8,9,10) of the hydraulic power booster piston (3), selectively connects an annular housing chamber (7) defined by a booster piston (3) to an unpressurised reservoir (21) or to both the chamber (19) via a seal (18) and the booster pressure chamber (5) via an inflow valve (17) which responds during a brake slip control action, and by switching over, or said 3/3-way valve (14) shuts off said annular housing chamber (7) hydraulically in a third switching position. A valve (22) closes the line to the reservoir (21) in the second position. <IMAGE>
Description
SPECIFICATION
Hydraulic brake system
This invention relates to an hydraulic brake system, in particular for automotive vehicles, with an hydraulic power booster and a master cylinder succeeding said power booster and having at least one working chamber, brake actuating members being connected to said working chamber, and with an apparatus for the limitation of pedal travel for which dynamic pressure medium is supplyable to the working chamber.
An hydraulic brake system with the forementioned features is known from the West
German patent application published without examination, No.2,452,952. The brake system described therein is furnished with a housing in which a hydraulic power booster with a succeeding tandem master cylinder is accommodated. In this context, the hydraulic power booster is equipped with a brake valve by means of which a pressure is adjustable in the pressure (booster) chamber of the hydraulic power booster which is proportional to the force of actuation exerted in each instance on the brake pedal.The housing of the brake valve is supported in this configuration, through a compression spring, at a return sleeve which surrounds an extension of the booster piston in the manner of a ring and defines an annular chamber of the housing within which the pressure level can be brought about that has been adjusted through the brake valve. In a configuration of this kind a limitation of the pedal stroke thus, results for the time the supply of external (auxiliary) energy is sound, the return sleeve allowing to be shifted along in the direction of actuation in the event of a failure of the auxiliary energy, so that the working chambers of the master cylinder can be pressurised by purely mechanical means.It is, furthermore, envisaged in the known brake pressure generating assembly that dynamic pressure medium flows into the working chambers via sealing cups arranged at the master cylinder piston which act as nonreturn valves.
In the known brake pressure generating assembly, it has to be considered less advantageous that the overall length of the brake pressure generating assembly increases considerably due to the use of the return sleeve.
Beyond this, the return sleeve constitutes a component which is sealedly guided at the housing, on one side, and at the extension of the booster piston, on the other side, as a result whereof corresponding frictional forces originate which oppose an actuation of the brake in case of failure of the auxiliary energy.
It is, therefore, an object of the present invention to further develop a brake system of the type mentioned in the beginning in such a manner that a limitation of the pedal travel is safeguarded by but simple means.
According to the present invention there is provided an hydraulic brake system with an hydraulic power booster and a master cylinder succeeding said power booster and comprising at least one working chamber, brake actuating members being connected to said working chamber, and with an apparatus for the limitation of pedal travel for which dynamic pressure medium is supplyable to said working chamber, characterised in that a valve device is connected to a pressure chamber of the said hydraulic power booster, in particular a 3/3-way valve by means of which an annular housing chamber defined by a booster piston is linked either to an unpressurised pressure medium reservoir or to said pressure chamber depending on the axial position of said booster piston and on an inflow valve responding during a brake slip control action, and in that the said valve device shuts off the said annular housing chamber hydraulically in one switching position.
In a configuration of this kind, it is attained in an advantageous manner that the annular housing chamber defined by the booster piston is connected to the unpressurised reservoir as long as the travel of actuation of the booster piston has not exceeded a distance which is pre-established by the specific design. During a brake slip control action, the 3/3-way valve can be switched into a second switching position in which the annular housing chamber is separated hydraulically from the pressure chamber of the hydraulic power booster, as a result whereof the booster piston largely maintains its momentary axial position, independently of the pressure which has been adjusted in the pressure chamber.In the event of a continued slide of the booster piston, the 3/3-way valve will, finally, assume a position in which the annular housing chamber is connected to the pressure chamber of the hydraulic power booster, so that a component of force is exerted on the booster piston of the hydraulic power booster which leads to a shift of the booster piston in the direction of release of the brake. In this context, the return of the booster piston is limited in that the 3/3-way valve finally assumes a middle position again in which the pressure chamber of the hydraulic power booster is separated from the annular housing chamber, a link between said annular housing chamber and the unpressurised reservoir being interrupted at the same time.
In an advantageous version of the subject matter of the application, it is envisaged that a 2/2-way valve is connected to the annular housing chamber which normally establishes a link to the unpressurised reservoir and which switches into a blocking position in the event of a brake slip control action. Such a configuration makes sure in any case that the annular housing chamber is separated anyhow from the unpressurised reservoir as soon as the 3/3-way valve is shifted out of its basic position.
In one advantageous embodiment of the subject matter of the application provision is made that the said 2/2-way valve is commutatable hydraulically by the pressure existing in the pressure chamber of the power booster.
In case of a solution of this kind, the drive of the 2/2-way valve is connected, preferably through the inflow valve, to the pressure chamber of the hydraulic power booster, so that a separate control of the 2/2-way valve by the electronic slip control system can be avoided.
An embodiment of the invention will now be described in more detail with reference to a basic connection diagram shown in the accompanying drawing.
In the drawing, reference numeral 1 denotes the housing of a hydraulic power booster 2 by means of which a master cylinder (not shown in detail) is actuatable. Said hydraulic power booster 2 is comprised of a stepped booster piston 3 which is abuttable against the housing 1 through a pedal-side annular collar 4.
Said booster piston 3 defines a pressure (booster) chamber 5 which, through a brake valve (not shown) is subjectable to a pressure proportional to the specific force of actuation
F exerted on brake pedal 16 in each individual instance.
The booster piston 3 comprises a piston step 6 with a large diameter, said piston step bounding an annular housing chamber 7, on one side, and the pressure chamber 5 of the hydraulic power booster 2, on the other side.
The end of the booster piston 3 projecting into the pressure chamber 5 of the hydraulic power booster 2 is divided into three sections 8, 9, 10 with different diameters, the piston section 8 having the largest and the piston section 10 the smallest diameter. In this configuration, said piston sections 8, 9, 10 are interconnected through sloped portions 11,
12, so that a tappet rod 13 which serves to actuate 3/3-way valve 14 may move along the outer contour of the booster piston 3 and actuates said 3/3-way valve 14 depending on the axial position of the booster piston.Within the end of the booster piston 3 disposed near the pedal, an actuating piston 15 is guided which is slidable by the brake pedal 16 and in the event of such a slide, adjusts a pressure in the pressure chamber 5 of the hydraulic power booster 2 which is substantially proportional to the force of actuation F exerted on the brake pedal 16. To said pressure chamber 5 of the hydraulic power booster 2, there is connected an inflow valve 17 which is configured in the form of a 3/2-way valve and normally ensures that the pressure chamber 5 is shut off hydraulically.Said inflow valve 17 is controllable by an electronic slip control system (not shown) and during a brake slip control action connects the pressure chamber 5, through a sealing cup 18 acting as a nonreturn valve, to a power (working) chamber 19 of the master cylinder, brake actuating members 20 being linked to the working chamber 19.
The 3/3-way valve 14 is connected to the exit of the inflow valve 17 and has a first switching position in which the annular housing chamber 7 is linked to an unpressurised reservoir 21, whereas a connection between the pressure chamber 5 of the hydraulic power booster and the annular housing chamber 7 is interrupted independently of what the position of the inflow valve 17 may be.
In a second switching position of the 3/3way valve 14, the annular housing chamber 7 is separated from the unpressurised reservoir 21. In a third switching position of the 3/3way valve 14, the annular housing chamber 7 of the brake pressure generating assembly is linked to the pressure chamber 5 of the hydraulic power booster 2, the unpressurised reservoir 21 being simultaneously shut off from the annular housing chamber 7.
Said annular housing chamber 7 of the hydraulic power booster 2 is, furthermore, in connection with the unpressurised reservoir 21 through a 2/2-way valve 22. Said 2/2-way valve 22 has a switching position in which the annular housing chamber 7 is shut off from the unpressurised reservoir 21. The drive of the 2/2-way valve 22, too, is linked to the exit of the inflow valve 17, so that the valves 17, 22 are commutated nearly at the same moment.
In the following, the mode of operation of the described brake system will be explained in more detail, based on the release condition of the brake in which all moving components will assume the position revealed by the drawing. When force is applied to the brake pedal 16, the actuating piston 15 will slide in the direction of brake actuation (to the left as viewed in the drawing), as a result whereof hydraulic pressure will be adjusted in the pressure chamber 5 of the hydraulic power booster 2 through a brake valve (not shown).
As soon as the pressure adjusted in the pressure chamber 5 of the hydraulic power booster 2 has exceeded the pressure of response of the hydraulic power booster 2, the booster piston 3 will move in the direction of actuation, whereby a hydraulic pressure will be generated in the working chamber 19 of the brake pressure generating assembly and in the brake actuating members 20 connected to said working chamber 19. In this operating condition, the annular housing chamber 7 is connected to the unpressurised reservoir through the 3/3-way valve 14, on one side, and through the 2/2-way valve 22, on the other side.
In the event of an increase of the force brought to bear on the brake pedal 16, the pressure in the pressure chamber 5 of the hydraulic power booster 2 will also rise, whereby the booster piston 3 will be shifted further in the direction of actuation. The tappet rod 13 of the 3/3-way valve 14 which takes support at the booster piston 3 may, during this procedure, come in engagement with the sections 9, 10 of the booster piston 3, as a result whereof the 3/3-way valve 14 will each time change its switching position. A commutation of the 3/3-way valve 14 will, however, be without importance in these operating conditions, since the annular housing chamber 7 of the hydraulic power booster 2 has a permanent connection to the unpressurised reservoir through the 2/2-way valve 22.
Let us now assume that a vehicle wheel related to the brake actuating member 20 presents a critical value of slip, while the tappet rod 13 of the 3/3-way valve 14 is still supported at the section 8 of the booster piston 3. In such an operating condition, first of all the inflow valve 17 will be commutated, whereby the pressure existing in each instance in the pressure chamber 5 of the hydraulic power booster 2 will be conveyed to the working chamber 19 of the brake pressure generating assembly. At the same time, the 2/2-way valve 22 will switch into a blocking position in which the annular housing chamber 7 of the hydraulic power booster 2 will be shut off from the reservoir.Since the 3/3-way valve 14 will, however, still remain in its basic position, there will continue to exist a pressure balance between the annular housing chamber 7 and the unpressurised reservoir 21, so that due to a withdrawal of pressure medium from the actuating member 20, the booster piston will be shifted to the left when viewing the drawing until upon having passed over the sloped portion 11, the tappet rod 13 of the valve 14 will come in abutment against the section 9 causing the valve 14 to assume its middle position. In this operating condition, the annular housing chamber of the hydraulic power booster 2 is shut off hydraulically, so that any further slide of the booster piston 3 in the direction of actuation will be excluded.
It is, thus, safeguarded that a sufficient minimum volume will be available in the working chamber 19 of the brake pressure generating assembly.
Let us, then, assume that the booster piston 3, for example in the event of increased friction values of the road, has already shifted to such an extent in the direction of actuation that the tappet rod 13 of the valve 14 comes to rest on the section 10 of the booster piston 3. If in such an operating condition a critical value of slip comes about again at the vehicle wheel related to the brake actuating member 20, then the inflow valve 1 7 will again switch over, as a result whereof the 2/2-way valve 22 will almost simultaneously assume a blocking position. The annular housing chamber 7 of the hydraulic power booster 2 is now connected to the pressure chamber 5 of the hydraulic power booster through the 3/3-way valve 14, whereby pressure will be brought to bear on the booster piston 3 in the direction of brake release.By suitably dimensioning the surfaces which are effective in this case, it is envisaged that the booster piston 3 of the hydraulic power booster 2 slides in the direction of brake release until the tappet rod 13 of the valve 14 comes to be abutted against the section 9 of the booster piston 3 upon having passed over the sloped portion 12 and until the valve 14 comes to assume a position in which the annular housing chamber 7 is shut off again hydraulically, so that any further shift of the booster piston in the direction of actuation will be excluded.
It will, therefore, be appreciated from the foregoing description of functioning that during the brake slip control action, the booster piston 3 of the hydraulic power booster will in any case assume a position in which the tappet rod 13 of the valve 14 is brought in abutment against the section 9 of the booster piston 3. In this axial position of said booster piston 3, the working chamber 19 of the brake pressure generating assembly will always enclose such a volume as is sufficient for the emergency actuation of the brake actuating members 20, even if the assistance by the auxiliary hydraulic power should fail.
Any pressure medium withdrawn from the brake actuating member 20 in the course of the brake slip control action will be balanced directly from the pressure chamber 5 of the hydraulic power booster through the sealing cup 18.
Restrictions are provided in the valve 14 in the switching positions in which the tappet rod 13 of the valve 14 is in abutment against the section 8 or against the section 10 in order to delay the axial movements of the booster piston 3 during the brake slip control action.
Claims (5)
1. An hydraulic brake system with an hydraulic power booster and a master cylinder succeeding said power booster and comprising at least one working chamber, brake actuating members being connected to said working chamber, and with an apparatus for the limitation of pedal travel for which dynamic pressure medium is supplyable to said working chamber, characterised in that a valve device is connected to a pressure chamber (5) of the said hydraulic power booster (2), in particular a 3/3-way valve (14) by means of which an annular housing chamber (7) defined by a booster piston (3) is linked either to an unpressurised pressure medium reservoir (21) or to said pressure chamber (5) depending on the axial position of said booster piston (3) and on an inflow valve (17) responding during a brake slip control action, and in that the said valve device (14) shuts off the said annular housing chamber (7) hydraulically in one switching position.
2. An hydraulic brake system as claimed in claim 1, characterised in that a 2/2-way valve (22) is connected to the said annular housing chamber (7) and normally establishes a link to the said unpressurised reservoir (21) and which 2/2-way valve (22) switches into a blocking position in the event of a brake slip control action.
3. An hydraulic brake system as claimed in claim 2, characterised in that the said 2/2way valve (22) is commutatable hydraulically by the pressure existing in the said pressure chamber (5) of said power booster (2).
4. An hydraulic brake system as claimed in claim 3, characterised in that the drive of the said 2/2-way valve (22) is connectible, through the said inflow valve (17), to the said pressure chamber (5) of said hydrauiic power booster (2).
5. An hydraulic brake system substantially as herein described with reference to and as illustrated in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19853521835 DE3521835A1 (en) | 1985-06-19 | 1985-06-19 | HYDRAULIC BRAKE SYSTEM |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8614205D0 GB8614205D0 (en) | 1986-07-16 |
| GB2176855A true GB2176855A (en) | 1987-01-07 |
| GB2176855B GB2176855B (en) | 1988-11-16 |
Family
ID=6273595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08614205A Expired GB2176855B (en) | 1985-06-19 | 1986-06-11 | Hydraulic brake system |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3521835A1 (en) |
| FR (1) | FR2583694B1 (en) |
| GB (1) | GB2176855B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4828333A (en) * | 1987-08-07 | 1989-05-09 | Alfred Teves Gmbh | Slip-controlled brake system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3736059A1 (en) * | 1987-10-24 | 1989-05-03 | Teves Gmbh Alfred | Hydraulic booster for a motor vehicle brake system and an antilock hydraulic brake system with a booster of the said type |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2452952A1 (en) * | 1974-11-08 | 1976-08-12 | Teves Gmbh Alfred | DUAL-CIRCUIT BRAKE SYSTEM |
| DE3040561A1 (en) * | 1980-10-28 | 1982-05-27 | Alfred Teves Gmbh, 6000 Frankfurt | FOREIGN ENERGY FEED BRAKE SLIP CONTROL SYSTEM OF A HYDRAULIC VEHICLE BRAKE SYSTEM |
| DE3240404C2 (en) * | 1982-11-02 | 1993-11-11 | Teves Gmbh Alfred | Hydraulic brake system with slip control |
| DE3338250A1 (en) * | 1983-10-21 | 1985-05-02 | Alfred Teves Gmbh, 6000 Frankfurt | HYDRAULIC BRAKE SYSTEM WITH SLIP CONTROL |
| DE3347618A1 (en) * | 1983-12-30 | 1985-07-18 | Daimler-Benz Ag, 7000 Stuttgart | HYDRAULIC TWO-CIRCUIT BRAKE SYSTEM FOR ROAD VEHICLES |
| DE3405967A1 (en) * | 1984-02-18 | 1985-08-22 | Alfred Teves Gmbh, 6000 Frankfurt | HYDRAULIC BRAKE SYSTEM WITH SLIP CONTROL |
-
1985
- 1985-06-19 DE DE19853521835 patent/DE3521835A1/en not_active Withdrawn
-
1986
- 1986-06-11 GB GB08614205A patent/GB2176855B/en not_active Expired
- 1986-06-19 FR FR8608830A patent/FR2583694B1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4828333A (en) * | 1987-08-07 | 1989-05-09 | Alfred Teves Gmbh | Slip-controlled brake system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2176855B (en) | 1988-11-16 |
| FR2583694A1 (en) | 1986-12-26 |
| GB8614205D0 (en) | 1986-07-16 |
| FR2583694B1 (en) | 1989-07-13 |
| DE3521835A1 (en) | 1987-01-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940611 |