GB1585563A

GB1585563A - Braking system

Info

Publication number: GB1585563A
Application number: GB305980A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-05-24
Filing date: 1977-05-23
Publication date: 1981-03-04
Also published as: JPS52148779A; PT66577A; AR215003A1; JPS6150817B2; IT1082093B; AU513895B2; BR7703306A; PL134253B1; GB1585562A; FR2352697B1; NL7705196A; FR2352697A1; PL198373A1; SE419427B; AU2508277A; MX144393A; SU1373308A3; CS235062B2; BE854932A; ES459063A1

Description

PATENT SPECIFICATION

( 21) Application No 3059/80 ( 22) Filed 23 May 1977 ( 62) ( 31) Divided out of No 1585562 Convention Application No 7605861 ( 32) Filed 24 May 1976 in ( 33) Sweden (SE) ( 44) Complete Specification Published 4 Mar 1981 ( 51) INT CL B 60 T 8/04 13/12 ( 52) Index at Acceptance F 2 F 611 665 C ( 54) IMPROVEMENTS IN OR RELATING TO A BRAKING SYSTEM ( 71) We, FOLKE IVAR BLOMBERG.

of Duvstigen 4, 181 40 Lidingo, Sweden, and JAN-OLOV MARTIN HOLST, of Skogsduvevagen 14, 752 52 Uppsala, Sweden, both Swedish subjects, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

This invention relates to a braking system and more particularly to a braking arrangement for braking a rotating member.

A great deal of work has recently been devoted to brakes for slowing rotation of a rotating member at an optimum rate Much of this work has arisen in the automotive vehicle field, where it is desirable that a passenger car or truck or lorry be brought to a stop within the shortest possible distance while retaining directional stability and control In efforts to obtain the shortest possible braking distances, provision has been made for increasing the braking force above that available simply from the muscular strength of a vehicle operator or driver Such power assisted braking systems have received wide acceptance and are in general use Whilst the use of power brakes and power assisted brakes have dramatically decreased stopping distances, difficulties have arisen with maintaining directional stability and control In the hands of an inexperienced operator or driver, an automotive vehicle equipped with power brakes or power assisted brakes is significantly more likely to experience wheel locking and skidding than a vehicle equipped with conventional brakes which are not power assisted At least partially for this reason, effort has been devoted recently to the development of anti-lock brake modulators, which controllably interrupt and relieve the application of fluid pressure to a brake when locking of a wheel is detected or is imminent While such anti-lock modulators have achieved some success and promise the achievement of desirable goals for braking efficiency, the use of such modulators with power brakes exposes the modulators to relatively high fluid pressures with consequent high rates of wear.

According to one aspect of this invention there is provided a braking arrangement for braking a rotating member comprising a fluid pressure actuated brake for slowing the rotating member; a master cylinder for applying fluid pressure to said brake; a booster comprising a booster cylinder containing a piston, the piston being operatively connected to said master cylinder so that said master cylinder is actuated in response to movement of said piston; hydraulic fluid circulating means operatively communicating with said booster cylinder for circulating hydraulic fluid through said cylinder and through a channel formed in the piston; an operator actuated brake rod movable to engage said piston within the booster cylinder to move said piston to actuate said master cylinder, said brake rod being adapted to close or partially close said passage through said piston when said brake rod is moved towards said piston, the closure or partial closure of said passageway giving rise to a differential in hydraulic fluid pressure across the piston so that the piston operates to impose an increase in the fluid pressure applied to said brake to a pressure higher than the pressure applied by said operator actuated brake rod when operated without the booster; a sensor for signalling the occurrence of an excessive rate of retardation of the braked rotation member; and a booster spoiler operatively connected with said booster and said sensor and responsive to a signalled occurrence of an excessive rate of retardation for reducing the said increase in fluid pressure applied by the booster, said booster spoiler comprising a valve assembly for diverting fluid pressure forces which would otherwise be imposed on said booster a tn ( 11) 1 585 563 1,585,563 cylinder by said hydraulic fluid circulating means.

In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a partially schematic and partially sectional view of a hydraulic booster braking arrangement in accordance with the present invention; and Figure 2 is a view similar to Figure 1, illustrating a modified form of the braking arrangement of that Figure.

Like references refer to like parts in both the Figures.

Figures 1 and 2 of the drawings illustrate two power brake systems for braking rotating members installed in an automotive vehicle, and each incorporating a master cylinder 11 which actuates fluid pressure actuated brake means (not shown) for slowing the vehicle wheels The master cylinder 11 is operator actuated, but the master cylinder has operatively connected therewith a booster, which forms part of a hydraulic fluid circulating system, for increasing the fluid pressure imposed on the brake means to a pressure higher than the pressure imposed solely by the action of the human operator.

In each system, a booster cylinder means 12 is interposed between the master cylinder 11 and means for actuation of the master cylinder by an operator, illustrated in the form of a brake pedal 13 A piston 17 within the booster cylinder 12 is operatively connected with the master cylinder 11 so that the master cylinder is actuated in response to movement of the piston 17.

Referring now more particularly to Figure 1, a pump 14 withdraws hydraulic fluid from a reservoir 15 and delivers the hydraulic fluid to the booster cylinder means 12 A flow path is maintained through a passageway 16 in a piston 17 which is movable within the booster cylinder means 12, so that fluid pumped from the reservoir 15 by the pump 14 may be returned thereto By means of a truncated conical tip 18 formed on a brake rod 19 coupled to the pedal 13, flow of fluid through the passage 16 is restricted or terminated upon an operator applying pressure to the pedal 13 thereby leading to a booster assistance effect obtained by the force of hydraulic pressure delivered by the pump 14 acting against the area of the piston 17 Thus, when the operator actuates the pedal 13 a certain pressure is applied to the master cylinder by the transmission of force from the pedal 13 via the rod 19 to the master cylinder 11 However, this force is boosted by the hydraulic pressure differential, created by closing the passage 16, that exists across the piston 17.

A booster spoiler means 20 for reducing, under certain circumstances, the effect of the hydraulic fluid power brake system of Figure 1 takes the form of a solenoid operated controllable return valve means interposed bet 70 ween the pump 14, which comprises hydraulic fluid circulating means, and the booster cylinder means 12 for interrupting the application of hydraulic fluid from the pump 14 to the booster cylinder means 12 More 75 specifically, the booster spoiler 20 of Figure 1 has a valve spindle or spool 21 normally maintained in a first position by the action of a spring 22 In such position, passageways permitting normal hydraulic fluid flow from 80 the pump 14 to the booster cylinder means 12 and back to the reservoir 15 provide the necessary communication for normal operation of the braking system When wheel slip is detected, by sensors associated with one or 85 more wheels (which may be sensors of type disclosed in United States Patent 3,833,097, for example) or when excessive retardation by appropriate sensors (not shown) an appropriate signal is applied to conductors 90 23 Thus energization of a solenoid winding 24 occurs, causing movement of an armature (to the right, as shown in Figure 1), the valve spindle or spool 21 thus being shifted to interrupt the hydraulic fluid circuit and to 95 provide return flow passages by which the flow of hydraulic fluid from the pump 14 is returned directly to the reservor 15 At the same time, the hydraulic fluid pressure differential appearing across the piston 17 is 100 equalised or levelled and the booster effect is spoiled and will cease Persons familiar with such hydraulically assisted power brake systems will be able to apply such a return valve means in systems of the type known and illus 105 trated in prior patents.

In distinction from the arrangement of Figure 1, the arrangement of Figure 2 provides a solenoid operated controllable reversing valve means in the booster spoiler 110 means 20 ' As will be noted, the passageways in the spindle or spool 21 ' are such that when the spindle 21 ' has been moved to the right as shown in Figure 2 in response to a signalled wheel slip the passageways provide a 115 cross-flow path by which the differential of hydraulic fluid pressure forces imposed across the piston 17 is reversed In this case.

the booster effect will not only be cancelled during activation of the system in response to 120 a wheel slip but the pump 14 will assist in generating an opposite force acting against the force applied to the brake pedal by an operator when the wheel retardation sensor has signalled that wheel locking is imminent 125 Persons skilled in the applicable arts will appreciate that controlled flow devices capable of accomplishing control over rate and extent of diminution or reversal of booster effect can be applied to the hydraulic fluid 130 1,585,563 pressure power brake systems of Figure 1 and 2 Thus, for example, a modulator as described in U K Patent Application No.

6467/76 (Serial No 1,544,443) may be operatively connected in the conduit that connects the master cylinder 11 and the fluid pressure actuated brake means.

Similarly, persons skilled in the applicable arts of designing brake control systems for automotive vehicles will appreciate a variety of approaches which may be used to apply the present invention In perhaps the simplest form, a single brake master cylinder having a single booster and booster spoiler may respond to a single sensor means operatively connected with one or more vehicle wheels.

Somewhat more sophisticated systems may employ plural boosters each with a corresponding booster spoiler and with each booster spoiler under the control of one or more sensors By such arrangements, sensors may be provided for individual non-driven wheels and for paired driven wheels Further, sensors may be provided for individual driven wheels, with the sensors being paired for control of a booster spoiler for the corresponding wheels Other and further permutations of such arrangement will be brought to mind by these brief comments, such as arrangements in which all wheels are provided with wheel retardation sensors, the front and rear axles each having a booster spoiler device.

Yet another arrangement might provide an individual retardation sensor and booster spoiler device for each of the rear wheels while the front wheels have a common wheel retardation sensor and booster spoiler.

Finally, each wheel may have its own wheel retardation sensor and its own booster spoiler device As will be recognized by skilled persons, the use of brake modulators may be similarly permutated in that one modulator may be provided for an entire system, or one modulator may be provided for each wheel, or sharing arrangements of various forms may be used This invention is contemplated as being useful with all such arrangements.

Claims

WHAT WE CLAIM IS:

1 A braking arrangement for braking a rotating member comprising a fluid pressure actuated brake for slowing the rotating member; a master cylinder for applying fluid pressure to said brake; a booster comprising a booster cylinder containing a piston the piston being operatively connected to said master cylinder so that said master cylinder is actuated in response to movement of said piston; hydraulic fluid circulating means operatively communicating with said booster cylinder for circulating hydraulic fluid through said cylinder and through a channel formed in the piston; an operator actuated brake rod movable to engage said piston within the booster cylinder to move said piston to actuate said master cylinder, said brake rod being adapted to close or partially close said passage through said piston when said brake rod is moved towards said piston, the closure or partial closure of said pas 70 sageway giving rise to a differential in hydraulic fluid pressure across the piston so that the piston operates to impose an increase in the fluid pressure applied to said brake to a pressure higher than the pressure applied by 75 said operator actuated brake rod when operated without the booster; a sensor for signalling the occurrence of an excessive rate of retardation of the braked rotating member; and a booster spoiler operatively connected 80 with said booster and said sensor and responsive to a signalled occurrence of an excessive rate of retardation for reducing the said increase in fluid pressure applied by the booster, said booster spoiler comprising a 85 valve assembly for diverting fluid pressure forces which would otherwise be imposed on said booster cylinder by said hydraulic fluid circulating means.

2 A braking arrangement according to 90 claim 1 wherein said valve assembly comprises a return valve interposable between said circulating means and said booster cylinder for providing a recirculation flow path bypassing said booster cylinder and a 95 second flow path for equalising fluid pressure forces imposed across the piston within said booster cylinder.

3 A braking arrangement according to claim 1 wherein said valve assembly com 10 ( prises a reversing valve interposable between said circulating means and said booster cylinder for reversing the differential of fluid pressure forces imposed across the piston within said cylinder 10 '

4 A braking arrangement according to any one of the preceding claims wherein said valve assembly is solenoid actuated.

A braking arrangement according to any one of the preceding claims wherein said 11 ( passageway in said piston within the booster cylinder defines a conical seat and said brake rod is provided with a conical tip adapted to co-operate with said conical seat.

6 A braking arrangement substantially 11 as herein described with reference to and as illustrated in Figure 1 of the accompanying drawings.

7 A braking arrangement substantially as herein described with reference to and as 121 illustrated in Figure 2 of the accompanying drawings.

8 An automotive vehicle provided with a braking arrangement in accordance with any one of the preceding claims 12 ) 4 1585 563 4 FORRESTER, KETLEY & CO Chartered Patent Agents Forrester House, 52 Bounds Green Road, London N 11 2 EY and also at Rutland House 143 Edmund Street Birmingham, B 3 2 LD and Scottish Provident Building 29 St Vincent Place Glasgow G 1 2 D 1 Agents for the Applicants Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey 1981.

Published by The Patent Office, 25 Southampton Buildings, London WC 2 A IAY, from which copies may be obtained.