GB2049852A - An hydraulic brake force booster - Google Patents

An hydraulic brake force booster Download PDF

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Publication number
GB2049852A
GB2049852A GB8014187A GB8014187A GB2049852A GB 2049852 A GB2049852 A GB 2049852A GB 8014187 A GB8014187 A GB 8014187A GB 8014187 A GB8014187 A GB 8014187A GB 2049852 A GB2049852 A GB 2049852A
Authority
GB
United Kingdom
Prior art keywords
brake force
brake
force booster
booster
pressure
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
GB8014187A
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GB2049852B (en
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch 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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB2049852A publication Critical patent/GB2049852A/en
Application granted granted Critical
Publication of GB2049852B publication Critical patent/GB2049852B/en
Expired 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
    • B60T8/441—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 using hydraulic boosters
    • 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
    • B60T13/14—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 using accumulators or reservoirs fed by pumps
    • B60T13/142—Systems with master cylinder
    • B60T13/145—Master cylinder integrated or hydraulically coupled with booster

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Braking Systems And Boosters (AREA)

Abstract

A hydraulic brake force booster (1) for a multicircuit brake system for motor vehicles having a control valve (110) arranged in parallel with master cylinders (90, 100). The control valve (110) is arranged such that a force transmission device (17, 19, 20, 31) incorporating a travel-simulating spring (15) and provided between the control valve (110) and the master cylinders (90, 100) is guided concentrically of the control valve (110). The guide has a tubular member (17) which accommodates the travel- simulating spring (15). Furthermore, a fail-safe device having levers (31) is provided between the control valve (110) and the master cylinders (90, 100). An hydraulic form of the fail- safe device is also disclosed. <IMAGE>

Description

SPECIFICATION An hydraulic brake force booster The invention relates to an hydraulic brake force booster for a multi-circuit brake system.
In particular the invention relates to a hydraulic brake force booster which is actuable by a brake pedal by way of a travel-simulating spring and which has a control valve which controls communication between a pressure source and a master cylinder and between the master cylinder and a relief point. A brake booster of this kind is known (German Offenlegungsschrift 27 02 891).
Although the control valve is disposed parallel to the master cylinder in the known construction, an "intergrated" brake booster of this kind takes up a considerable amount of installation space.
Furthermore, the guidance of the actuating linkage disposed beyond the brake pedal causes difficulties, since it can only be provided by additional means which are expensive and take up space.
In accordance with the present invention there is provided an hydraulic brake force booster for a multi-circuit brake system, which booster is actuable by way of a travel giving spring and has a control valve which controls communication between a pressure source and one master cylinder and between that master cylinder and a relief point, the control valve being disposed parallel to the master cylinders and being arranged to be coupled thereto by means of a force transmission device, a guide being provided for the force transmission device and being disposed concentrically of the control valve.
In contrast to the prior art, the hydraulic brake booster in accordance with the invention has the advantages that the weight and volume of the construction is substantially reduced. Moreover, lateral forces acting upon the actuating linkage are avoided by mounting the power transmission device concentrically.
The present invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a first embodiment of a brake booster, Figure 2 shows a second embodiment of a booster with hydraulic force transmission, Figure 3 shows a modification of the brake force booster with hydraulic force transmission, and Figure 4 shows a type of construction with integrated accumulator.
A hydraulic brake booster 1 is arranged in a hydraulic brake system between a brake pedal 2 and two pairs of wheel brake cylinders 3, 3' and 4, 4'. One pair 3, 3' of wheel cylinders forms part of a brake circuit I, and the other pair 4, 4' of wheel cylinders forms part of a brake circuit II. The two brake circuits I and II are monitored by a multiple adjusting member 5 of an automatic anti-lock system.
The brake force is boosted by means of a pressure source which comprises a pump 6 and an accumulator 7 and which is connected to a housing 8 of the brake booster 1.
Three parallel bores 9, 10 and 11 are provided in the housing 8 of the brake booster 1, the two bores 9 and 10 being intended for two master cylinders 90 and 100. The bore 11 is located between the two master cylinders 90 and 100 and accommodates a control valve 110 in the form of a slide valve.
One end of a spool 12 of the control valve 110 is sealed by means of an O-ring 13 to extend out of the housing 8 where it is provided with an enlarged protion 14, one side of which enlarged portion serves as a contact surface for a travelgiving spring 1 5 and the other side of which is engaged by an inwardly bent end 16 of a tubular member 1 7. In this manner, the travel-giving spring 1 5 is inserted under initial stress into the tubular member 17. A device 17' for preventing rotation of the tubular member 1 7 is provided in the housing 8 of the brake booster 1.
The tubular member 17 is guided in a hollow cylindrical extension 1 8 of the housing 8, a seal not being used at this location. Furthermore, the tubular member 1 7 carries two arms 1 9 and 20 whose ends are located opposite two push rods 21 and 22 which in turn extend into the master cylinders 90 and 100 where they each carry a respective master cylinder piston 23, and 24.
In the present embodiment, each of the two master cylinder pistons 23 and 24 is equipped with two sealing rings for the purpose of media separation, although it is possible to use only one sealing ring in the case of a single-medium type construction.
A respective pressure chamber 25 and 26 is located at the secondary side of each piston 23 and 24, the pressure chamber 26 being connected to the brake circuit I by way of passage 27, and the other pressure chamber being connected to the brake circuit II by way of a passage 28.
A stop piston 29 is disposed coaxially beyond the control valve 110 and limits the travel of the spring 1 5 when the supply of pressure medium is intact.
A support point 30 for a lever 31 is disposed centrally between the axes of the two master cylinders 90 and 100 and within the outer wall of the tubular member 17, which lever has two arms 32 and 33 of equal length (lenghts L, and L2). The arms 32 and 33 abut against the fee ends of the push rods 21 and 22 which are provided with respective enlarged portions 34 and 35, and a respective return spring 36 and 37 for the master cylinder pistons 23 and 24 connected to the push rods 21 and 22 embraces the respective push rods between each enlarged portion 34 and 35 and the housing 8. The lever constitutes a safety device in the event of failure of the pressure medium.
The general mode of operation of the brake booster is described in the German Offenlegungsschrift 27 02 819 mentioned initially. In the construction in accordance with the invention, the tubular member 17 provides a guide for a force transmission device 17, 1 9, 20 31 which is disposed concentrically of the control valve 110.
This force transmission device renders it possible to reduce the weight and volume of the break force booster and also forms reception means for the travel-giving spring 1 5.
If the supply of pressure medium should fail, the arms of equal length of the lever 31 serve to transmit power directly from the pedal 2 to the push rods 21, 22 of the master cylinders 90 and 100. The leverage of the lever 31 can also be varied, although it is preferably chosen such that the ratio of L1 to L2 is equal to the ratio of the effective surface areas of the master cylinder piston 23 and 24.
Furthermore, the maximum brake pressure may be limited by appropriate dimensioning of the pressure mediurn supply, especially the pump, as well as the master cylinder pistons 23 and 24 and possibly the limitation of their maximum stroke by means of a stop, considerably lower pressures occur in the brake system than in the case of normal brake boosters in which very high brake pressures occur with high applied pedal forces owing to the fact that the booster and the master cylinder are arranged in tanden, without these levels of brake pressures being necessary. l High pressures of this kind require strong lines and powerful brake cylinders.
It has transpired that operation can be effected with lower brake pressures, particularly in the case of brake boosters combined with an anti-lock system. By virtue of its construction and design, the brake booster in accordance with the invention is eminently suitable for such low pressure actuation of the brakes.
Figure 2 shows a brake booster in which, the addition to other modifications, (the safety device) the mechanical force transmission device has been repiaced by a hydraulic force transmission device. The parts corresponding to the construction of Figure 1 are provided with the same reference numerals.
A barke booster 41 of the single-medium type has a tubular member 42 which is connected to the pedal 2 and which is guided concentrically of the control valve 110, the tubular member being provided with two longitudinally bored arms 43 and 44. The outer ends of the arms 43 and 44 accommodate pistons 45 and 46 which are located opposite the push rods 21 and 22. The rear ends of the pistons 45 and 46 are interconnected by a hydraulic linkage 47.
It will be seeen that, in the present instance, the equalization of force between the two master cylinders 90 and 100, required in the event of failure of the pressure supply, is effected by means of the hydraulic linkage 47 within the power transmission device. Dimensioning is determined by the effective ratio of the surface areas of the master cylinder pistons to that of the pistons 45 and 46.
In the present instance, the concentric guide of the power transmission device is protected by an additional bellows 48. The advantage of this measure resides in the fact that not special means have to be provided to protect the corresponding part of the power transmission device against corrosion. This also applies to the return springs 36 and 37 which, in this type of construction, are protectively arragned in respective suction chambers 49 and 50 in the master cylinders 90 and 100.
Based on the variant of Figure 2, Figure 3 shows a brake booster 51 in which the return springs 36 and 37 are again disposed on the push rods21 and 22.
Although Figures 1 to 3 show brake boosters each having two master cylinders 90 and 100, it is also possible to accommodate three master cylinders in the housing of a brake booster.
Figure 4 shows a brake booster 61 in which two master cylinders 90 and 18O and a control valve 110 (whose respective centre lines are indicated by chain dotted lines) are arranged in the same plane 62.
A construction of this type can also be provided for perpendicular installation. The housing of the brake booster 61 is combined with an accumulator 70 corresponding to the pressure accumulator 7. The accumulator 70 has an accumulator chamber 71 and an energy-storing spring 72 which is protected by a tube 73. The energy-storing spring 72 acts upon an accumulator piston 74 and, particularly for reasons of saving weight, is made from a carbon fibre reinforced plastics material.

Claims (20)

1. An hydraulic brake force booster for a multicircuit brake system, which booster is actuable by way of a travel-giving spring and has a control valve which controls communication between a pressure source and one master cylinder and between that master cylinder and a relief point, the control valve being disposed parallel to the master cylinders and being arranged to be coupled thereto by means of a force transmission device, a guide being provided for the force transmission device and being disposed concentrically of the control valve.
2. A brake force booster as claimed in claim 1, in which the guide comprises a tubular member, and the travel-giving spring is disposed within the tubular member.
3. A brake force booster as claimed in claim 1 or 2, in which the guide is provided with means for preventing rotation of the force transmission device with respect to the brake force booster.
4. A brake force booster as claimed in any of claims 1 to 3, in which a pressure failure safety device is provided between the master cylinders and the control valve.
5. A brake force booster as claimed in claim 4, in which the safety device comprises a lever whose lever arms act respectively on the master cylinders, the lengths of the lever arms conforming to the effective surface areas of the master cylinder pistons.
6. A brake force booster as claimed in claim 4, in which the safety device comprises a hydraulic linkage.
7. A brake force booster as claimed in any of claims 1 to 6, in which the guide is externally covered by a protective bellows.
8. A brake force booster as claimed in any of claims 1 to 7, in which a respective master cylinder return spring is provided outside each master cylinder.
9. A brake force booster as claimed in any of claims 1 to 7, in which a respective master cylinder return spring is provided in a respective replenishment feed chamber of the respective master cylinder.
10. A brake force booster, for a two-circuit brake system, as claimed in any one of claims 1 to 9, in which the control valve and the two master cylinders, in use are disposed with their axes vertical and substantially in the same plane.
11. A brake force booster as claimed in any of claims 1 to 10, in which the housing of the brake force booster is combined with a piston accumulator which is associated with the pressure source.
1 2. A brake force booster as claimed in claim 11, in which the piston of the piston accumulator is made from a carbon fibre plastics material and is subject to the force of an energy storing spring.
1 3. A brake force booster as claimed in any of claims 1 to 12, in which one and the same pressure medium is used for the pressure supply and the brake circuit.
14. A brake force booster as claimed in any of claims 1 to 12, in which two different pressure media are used for the pressure supply and the brake circuit.
1 5. A brake force booster as claimed in any of dims 1 to 14, in combination with an anti-wheel lock system.
1 6. A brake force booster as claimed in any of claims 1 to 15, in which the maximum possible brake pressure is limited.
1 7. A brake force booster as claimed in claim 1 6, in which the internal diameter of the master cylinders and the stroke of their pistons are so chosen as to limit the maximum possible brake pressure.
1 8. A brake force booster as claimed in claim 16, in which the maximum possible brake pressure is limited by pressure limiting in the secondary circuit.
1 9. A brake force booster as claimed in claim 16, in which the maximum possible brake pressure is limited by appropriate dimensioning of the pressure source.
20. An hydraulic brake force booster constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
GB8014187A 1979-05-10 1980-04-30 Hydraulic brake force booster Expired GB2049852B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19792918771 DE2918771A1 (en) 1979-05-10 1979-05-10 HYDRAULIC BRAKE POWER AMPLIFIER

Publications (2)

Publication Number Publication Date
GB2049852A true GB2049852A (en) 1980-12-31
GB2049852B GB2049852B (en) 1983-04-27

Family

ID=6070339

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8014187A Expired GB2049852B (en) 1979-05-10 1980-04-30 Hydraulic brake force booster

Country Status (3)

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JP (1) JPS55152653A (en)
DE (1) DE2918771A1 (en)
GB (1) GB2049852B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2510960A1 (en) * 1981-08-06 1983-02-11 Teves Gmbh Alfred MASTER CYLINDER ARRANGEMENT ASSISTED BY AN AUXILIARY FORCE FOR A MOTOR VEHICLE BRAKE SYSTEM
GB2136521A (en) * 1983-03-10 1984-09-19 Bosch Gmbh Robert Two-circuit brake system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2510960A1 (en) * 1981-08-06 1983-02-11 Teves Gmbh Alfred MASTER CYLINDER ARRANGEMENT ASSISTED BY AN AUXILIARY FORCE FOR A MOTOR VEHICLE BRAKE SYSTEM
GB2136521A (en) * 1983-03-10 1984-09-19 Bosch Gmbh Robert Two-circuit brake system

Also Published As

Publication number Publication date
GB2049852B (en) 1983-04-27
JPS55152653A (en) 1980-11-28
DE2918771A1 (en) 1980-11-20

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee