CA1099315A - Braking apparatus and method with booster and spoiler - Google Patents

Abstract

ABSTRACT
In a braking arrangement for a rotating member such as an automotive vehicle wheel and which has a fluid pressure actuated brake for slowing the rotating member together with a booster for increasing the fluid pressure imposed on the brake to a pressure higher than the pressure imposed by an operator, a sensor for sig-nalling the occurrence of an excessive rate of retardation of the braked rotating member and a booster spoiler operatively connected with the booster and the sensor and responsive to a signalled occurrence of an excessive rate of retardation for decreasing the increased fluid pressure imposed by the booster. The booster may be either pneumatic or hydraulic, with corresponding variations in the specific form for the booster spoiler.

Description

33~i This application i8 a divlsion o~ Canadian Applicatlon Serial No. 278,758 filed ~ay 19, 1977.
This invention relates to a braking system and method utlliz-ing a booster and spoiler therefor.
A great deal of work has recently been devoted to brakes for rotating members capable of slowing rotation of a braked member at an optimum rate. Much of this work has arisen out of the automotive vehicle field, where it is desirable that a passenger car or truck bebrought to a stop within the shortest possible distance while retaining directional stability and control. In efforts to obtain the shortest possible braking distances, provi~ion 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 accept-ance and are in general use.
While power brakes have dramatically decreased stopping distances, such brakes have introduced difficulty with maintaining directional stability and control. In the hands of an inexperienced operator or driver, an automotive vehicle equipped with power brakes can present a significantly greater danger of skldding and the like. At least partlally ~0 for this reason, effort has been devoted recently to the development of anti-lock brake modulators, which controllably interrupt and release the application of fluid pressure to a brake. While such anti-lock modulators have achieved some success and promise the achievement o~ 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 and st~ict design requirements.
In light of these circumstances, it has now been determined tha~
anti-lock contr~l in con~unctionwith power assisted brake systems may be achieved or at least facilitated by use of a booster spoiler eEfective for removing the booster effect othecwise supplled to the braking system.
Accordingly it is an ob~ect of the present invention to faclllt~e avoid-an~e of wheel locking and skidding otheewi9e resulting from excesslve brak-ing efforts, by diminishing the effect of increased brake pressure achieved through use of power asslsted brakes. Expre~sed differently, the present ~;

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invention l'spoils~' the effect of increased ~luid pressure imposed by means of the "booster" of a power brake system. In reali~ing this object of the prssen~ invention, provision is made ~or adaptation to power brake systems in which booster effects are achieved by imposition of air pres-sure differentials acros9 a diaphragm and those in which hydraulic fluid pressure differentials are imposed across the system.
Yet a further object of this inventlon is to accomplish a reduction in braking efect in response to signalled occurrences of an excessive rate of retardation of a braked rotating member such as a vehicle wheel, wlth or without the use of a brake modulator. In realizing this ob~ect of the present invention, the diminution of braking effect accom-plished by spoiling a booster effect has been found to be effective in reducing and in some instances removing a tendency for wheel locking and skidding of a vehicle.
Yet a further objec~ of this invention is to coordinate the operation of a brake modulator and a booster spoiler in such a way as to facilitate reduction in wear of brake modulators and more universal appli-cability thereof the braking systems of varying pressure and volume cap-abilities. In realizing this object of the present inven~ion, the increase in fluid pressure accomplished by the power assist booster of a braking system is "spoiled" or reduced during the operation of an associated modulator.
Thus by one aspect of this invention there is provided a brak-ing arrangement for a rotating member comprising fluid pressure actuated brake means for slowing the rotating member, operator actuated means communicating with said brake rneans for imposing fluid pressure on said brake means, booster means operatively connected with said operator actuated means for increasing the fluid pressure imposed on said brake means to a pressure higher than the pressure impo9ed by said operator actuated means and comprising diaphra~n means operatively connected to said operator actuated means and means operatively associated with ~aid diaphragm means for controllabl~J 9ub~ecting said diaphragrn means to a ~ 2 ~

fluid pressure d-lfferential thereacross, sensor means operatlvely connected with the rotating member for signalling the occurrence of an excessive rate of retardation of the braked rotating member, and booster spoiler means operatively connected with said booster means and said sensor means and responsive ~o a signalled occurrence of an excessive rate of retardation for decreasing the fluid pressure imposed by said booster means, said booster spoiler means comprising controll-able vent means for venting said means for sub~ecting said diaphragm means to fluid pressure and thereby for removing the fluid pressure differential across said diaphragm means.
By another aspect of this invention there is provided in a method of braking an automotive vehicle including supplying pressurized hydraulic fluid from an operator actuated device, controllably boosting the pressure of the hydraulic fluid to a pressure higher than the pressure supplied from the device by subjecting a diaphragm to a differential ~hereacross between atmospheric pressure and a pressure less than atmospheric, applying the pressurized hydraulic fluid to a wheel brake, sensing the occurrence of an excessive rate of retardation of the braked wheel and signalling such sensed occurrence, and modulating brak-~ng of the wheel in response to such signalling of a sensed occurrence, the improvement comprising controllably subjecting the diaphragm to atmospheric pressure on opposing sides thereof and thereby reducing the boost in the pressure of the hydraullc fluid in response to such signal-ling of a sensed occurrence and while the modulating of braking is occurring.
The invention will be described hereinafter with reference to the drawings in which:-Figure 1 is a partly schematlc, partly sect-ional view of a braking arrangement in accordance with the present tnvention and particularly adapted for a pneumatic vacuum booster;
Figure 2 is a view slmilar to Figure 1, showing a braking arrangement incorporating one form of modulator;

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3 ~i Figure 3 is a view similar to Figure 1~ showing a braking arrangement incorporating a pneumatic compressed air booster; and Figure 4 is a sectional view similar to a portion of Figure 1 illustrating a booster spoiler device with auxiliary servo assistance for accommodating larger air flow volumes.
While this invention will be described hereinafter with particular reference to the accompanying drawings, in which illustrative embodiments of the present invention are set forth, it is to be under-stood at the outset of the description which follows that it is contemplated that persons skilled in the applicable arts may modify the specific details to be described while continuing to use the significant and novel characteristlcs of this invention. Accordingly, the description is to be understood to be directed to persons skilled in the applicable arts as a broad teaching of this invention.
Referring now more particularly to the accompanying drawings, a braking arrangement for a rotating mem~er in accordance with the present invention typically is installed in an automotive vehicle. Such an automtoive vehicle (not shown) typically is equipped with fluid pressure actuated brake means for slowing a rotating member such as a vehicle wheel. Operator actuated means, typically in the form of a hydraulic Eluid master cylinder generally indicated at 11, are provlded for imposing 3~S

fluid pressure on the brake means. The master cylinder 11 has operatively connected th~rewith a booster means for increasing the fluid pressure imposed on the brake means 10 to a pressure higher than the pressure imposed ~y the operator actuated master cylinder.
In the specific orm of Figure 1, the booster means takes the form of a vacuum actuated diaphragm means generally indicated at 12.
The booster means 12 i5 operatively connected with the master cylinder 11 and is responsive thereto for exertion of a fluid pressure diferential across a diaphragm. Such vacuum ac uated boosters for power brake systems are generally well-known to persons skilled in the arts o~ designing brakes for automotive vehicles, and, accordingly, will not here be described in detail.
Interested readers seeking greater knowledge of such technology are referred to previously granted patents directed to such arran~ements.
By means of a conduit generally indicated at 14 and extending be~ween the diaphragm means 12 and an appropriate source of vacuum~ such as the inlet manifold of an internal combustion engine, provision is made for controllably subjecting the diaphragm means 12 to a fluid pressure dif ferential there-across, in a manner generally known to appropriately skilled persons~ While this description has been particularly directed to a brake arrangement wherein a differential pressure means comprises vacuum means for subjecting the diaphragm mea~s 12 to a differen-2S tial ~etween atmospheric pressure and a pxessure less khan atmospheric, it is also known to persons skilled in the applicable arts to employ a dif~erential pressure means which comprises a compressed air means for subjecting a diaphragm means to a di~erential between a~mospheric pressure and a pressure greater than atmospheric. While this invention will be described .

3~L5i hereinafter flrst With reference ~o a Vacuum ac~uated di~ph~agm mean8 12 it is intended that this invention have applicability to all such variations and forms of power brakes~
In accordance with the present invention, a booster spoiler means generally indicated at 15 is interposed in the conduit 14 by which pressure fluid differentials are applied to the diaphragm means 12. The booster spoiler ~eans 15 is thus operat~vely connected with the booster means for decreasing the fluid pressure differential imposed by the booster means as appropriate and as described more fully hereinafter.
The braking arrangement in accordance with the present invention additionally includes sensor means generally indicated at 16 for signalling the occurrence of an excessive rate of retardation o~ the brahed rotating vehicle wheel member. Preferably, the sensor means includes electrical swltch means for electrically signalling occurrences of an excessive rate of retardation by emitting a signal on appropriate conductors 17. Sensor means such as are indicated generally at 16 in the present drawings, for electrically signalling the occurrence of an excessive rate of retardation of a braked rotating member such as an automotive vehicle wheel, are kno~m ~o persons skilled in the appropriate arts and, for that reason, no full disclosure has been given. Interested readers seeking disclosure of such sensors are referred to Holst United States Patent 3,833,097, where a variety of such sensors are shown and described with reference to Figures 6-11 of that patent, and to Blomberg United States Patent 4,061,212. The sensors there sho~n or others known to skilled persons may be used in the arrangement of the present invention. Certain such sensors ~7ill be under-stood as signalling occurrences of wheel slip and 3~S

are, for purposes oE ~his description, deemed comparabl~ to - sensors signalling excessive rates o~ retardation4 The booster spoiler means of the present invention incorporates valve means operatively connected with the fluid pressure differential means provided by the diaphragm means 12 and responsive to the sensor means 16 for at least relieving the fluid pressure differential exerted by the differential means. In the form illustrated in Fig~re 1, which is suitable for vacuum actuated diaphragms of relatively small size such as are found on lightweight passenger-automobiles, the valve means comprises a valve spool or spindle 18 mounted within a housing 19 for movement relative thereto. The spindle 18 has mounted thereon a pair of valve discs 20, 21, each o~ which cooperates with a correspondi~g valve seat 22, 230 ~ne valv~ provided by one disc 21 and its cooperating seat 23 is interposed directly in the conduit 14 and controls communication therethrough, while the valve formed by the othsr disc 20 and its cooperating seat 22 controllably opens com~
munication between ~he diaphragm means 12 and the atmosphere, thus controllably venting the booster. The discs 20, 21 are coupled together by the spindle 18, in such a ~ay that seating of one disc requires that ~he other disc be unseated. A biasing spring 25 normally urges the other disc 20 into seating engagernent wi~h its corresponding seat 22, sealing against venting of the diaphragm means 12 and permitting normal booster operation in which communication through the conduit 14 is established by means of a central passageway 26 within the housing 19.
The position of the spindle 18 is additionally controlled by a solenoid including a winding 28 and a cooperating coxe or armature 29. The winding ~8 is electrically connected with the conductors 17 of the sensor ~eans 16/ for respondinc~ to an elec-trical si~nal indicative of an occurrence of an excessive rate ~7-~^

of retardatlon of a braked wheel by shifting the spindle 18 and discs 20, 21 against the force of th~ sprIng 25. As so sh~fted, the normally unseated disc 21 is sealingly engaged with its corresponding seat 23, while the normally seated disc 20 is displaced from its corresponding seat 22. Thus, the diaphragm means 12 is vented to the atmosphere through the central passageway 26 and a vent passageway 30 extending through the housing 19.
In order to control the rate of dlminishment o~ the booster effect and to prevent accidental entry into the houslng 19 of foreign matter, a controlled check valve generally indicated at 31 ls lnterposed between the atmosphere and the vent passageway 30. The check valve 31 includes a valve member 32 movable relative to an inlet passageway 34 against the bias of a regulating spring 35 and to an extent determined by a stop member 36. Threaded adJustment members 38, 39 are provided for the spring 35 and stop member 36 respectively, in order to permit regulation of both the rate of venting of the diaphragm means 12 and the vented pressure permltted in the diaphrag~ means. By regulation of the force exerted by the spring 35 and the extent to which the ve~t passageway is opened by positioning af the stop member 36, the rate and degree of diminishment of braking effor~ achieved in accordance wlth the present invention may be controlled.
An embodiment of the braking arrangement of this in~ention which incorporatec a modulator is shown in Figure 2, where one speciflc form of modulator is indicated generally at 50. As shown, the modulator is of a type descrlbed and clalmed in Blomberg and Holst United States Patent 4,068,904 issued January 17, 1978. The structure of the modulator 50 and its function will be made more clear from that description, which is hereby incorporated by refexence to any extent necessaxy to understanding of this invention, but persons skilled in the appropriate arts will know o~ other forms o~ modulators and understand their use in arrangemen~s according to this inVentiOn S Elements of the arrangement according to Fiyure 2 corresponding to elements of the arrangement of Figure 1 have been identified by similar reference characters with the addition of the letter a, and will not be here described.
It will be noted that the modulator 50 operates in response to a sensor l~a signal, as does the booster spoiler 15a. Mo~t conveniently, energiza~ion of the modulator 50 and booster spoiler 15a may occur simultaneously, but it is contem-plated that variations in sensor constructio~ and/or electrical circuitry may permit energization o the modulator 50 and booster spoiler 15a at any predetermined time relative to one another and to sensing of an exces~ive rate o~ ~heel retardation.
Fisure 3 illustrates an embodiment of a braking arrangement of this invention wherein a booster 12b of pneuma~ic compxessed air type is supplied from an engine driven compressor indicated generally at 51. Elements of Figure 3 corresponding to elements shown in Figures 1 and 2 have been identified by similar reference characters followed by the lettex b and the description of those elements will not be here repeated.
A modified form o~ the booster spoiler 15 of the pre~ent invention which is usable with pneumatic boosters having larger areas is illustrated in Figure 4, where components corres-ponding to components described above with reference to Figure 1 are identi~ied by like reference characters o a one hundred order series. The distinction between the booster spoiler 15 of Figure ~ and the booster spoiler 115 o~ Figure ~ is that the ~ 5 solenoid formed by the winding 128 and armature 12~ control~ a pilot valve spindle 118 which operates ~ servo valve including a spindle 140 which carries discs 141~ 142 ~or Coopera~ing with respective seats 14~, 145. l'he servo valve is operated by the same vacuum s~urc~ which supplies the vacuum boost for the vehicl.e brake system. The operation of the servo controllea booster spoiler 115 is substantially similar to the operation of th~ direct solenoid actuated booster spoiler lS described herei~above and it is accordingly deemed not necessary to repeat that description in full.
As will be appreciated, energization of the winding 128 caUses the armature 129 to shift against the action of the return sprin~ 125, moving the spindle 118 within the housing 119 so as to change the seating of the d.iscs 120, 121 against . their respective seats 122, 123. The central passageway 126 -will thus ~e.sealed from its normal co~unication with the atmosphere and the reduced pressure present in the conduit 114 will be admitted '~o a space 146 in which it m~y act against a membrane or diaphra~m 148 which has its other surface exposed to atmospheric pressureO A pressure differential across the membrane or diaphraym 1~8 will shift the servo spindle 140 thereby changing the seating of the discS 141~ 142 carried therehy wi~h respect to their ~orresponding sea~s 144, 145.
With such shifting of seating of th~ servo valve discs, that por~io~ o the conduit 114 leading to the booster diaphragm means tnot shown) is vented to the atmospllere.
In the form illus~rated in Figure 4~ a ~alve member 13~ is mounted on an adjustable member 138 for controllable positioning relati~e to an inlQt passageway 134~ As will.be appreciated, adjustment of position of the valve member 132 33L~

relative to the inlet passageway 134 will vary the rate at which the increase in braking force obtained through use of the booster is dlminished by operation of the booster spoiler 115.
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 pressure power brake systems described in parent Canadian Application 278,758 just as they are applied to the pneumatic power brake systems of Figures 1 through 4.
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 bo4ster 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 ` 20 and for paired driven wheels. Further, sensors may be provided for individual driven wheels, with the sensors being paired for control oE a booster spoiler for the corresponding wheels. Other and further permutations of such arrangements wlll 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, s each wheel may have its own wheel retardation sen~or and its own booster spoiler devi~e. As will ~e recognizea by skille~
persons, the use of brake modul~tors may be similarly permutated . in that sne modulatox ~may be provided for an entire system, or one modulator may be provided ~or each wheel, or sharing arrangements of various forms may be used. ~his invention is contemplated as being useful with all such arrangeI~ents.
In the drawings and specification, there has ~een set forth a preferred embodiment: of the invention, and although specific terms are employea, they are used in a generi~ and ~escriptive sçnse only and not ~or purposes of limitation.

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A braking arrangement for a rotating member comprising fluid pressure actuated brake means for slowing the rotating member, operator actuated means communicating with said brake means for imposing fluid pressure on said brake means, booster means operatively connected with said operator actuated means for increasing the fluid pressure imposed on said brake means to a pressure higher than the pressure imposed by said operator actuated means and comprising diaphragm means operatively connected to said operator actuated means and means operatively associated with said diaphragm means for controllably subjecting said diaphragm means to a fluid pressure differential thereacross, sensor means operatively connected with the rotating member for signalling the occurrence of an excessive rate of retardation of the braked rotating member, and booster spoiler means opera-tively connected with said booster means and said sensor means and responsive to a signalled occurrence of an excessive rate of retardation for decreasing the fluid pressure imposed by said booster means, said booster spoiler means comprising controllable vent means for venting said means for subjecting said diaphragm means to fluid pressure and thereby for removing the fluid pressure differential across said diaphragm means.

2. Apparatus according to claim 1 wherein said differential pressure means comprises compressed air means for subjecting said diaphragm means to a differential between atmospheric pressure and a pressure greater than atmospheric.

3. Apparatus according to claim 1 wherein said booster means comprises diaphragm means operatively connected to said operator actuated means and means operatively associated with said diaphragm means for controllably subjecting said diaphragm means to an air pressure differential thereacross;
said sensor means electrically signals the occurrence of an excessive rate of retardation of the braked rotating member, and said booster spoiler means is operatively connected with said diaphragm means and said sensor means and comprises solenoid controlled vent means responsive to a signalled occurrence of an excessive rate of retardation for decreasing the air pressure differential imposed thereacross.

4. A braking arrangement for a rotating member comprising fluid pressure actuated brake means for slowing the rotating member, operator actuated means communicating with said brake means for imposing fluid pressure on said brake means, booster means operatively connected with said operator actuated means for increasing the fluid pressure imposed on said brake means to a pressure higher than the pressure imposed by said operator actuated means and having diaphragm means controllably subjected to a differential thereacross between atmospheric pressure and a pressure less than atmospheric, sensor means operatively connected with the rotating member for signalling the occurrence of an excessive rate of retardation of the member, brake modulator means operatively connected with said brake means and said sensor means and responsive to signalling from said sensor means for decreasing and increasing the fluid pressure imposed on said brake means upon the occurrence of an excessive rate of retardation of the braked rotating member, and booster spoiler means operatively connected with said sensor means and said booster means and said modulator means and responsive to signalling from said sensor means for controllably subjecting said diaphragm means to atmospheric pressure on opposing sides thereof and thereby decreasing the fluid pressure imposed by said booster means during operation of said modulator means.

5. In a method of braking an automotive vehicle including supplying pressurized hydraulic fluid from an operator actuated device, controllably boosting the pressure of the hydraulic fluid to a pressure higher than the pressure supplied from the device by subjecting a diaphragm to a differential thereacross between atmospheric pressure and a pressure less than atmospheric, applying the pressurized hydraulic fluid to a wheel brake, sensing the occurrence of an excessive rate of retardation of the braked wheel and signalling such sensed occurrence, and modulating braking of the wheel in response to such signalling of a sensed occurrence, the improvement comprising controllably subjecting the diaphragm to atmospheric pressure on opposing sides thereof and thereby reducing the boost in the pressure of the hydraulic fluid in response to such signalling of a sensed occurrence and while the modulating of braking is occurring.

6. A method according to claim 5 wherein the step of reducing the boost comprises reducing the pressure of the hydraulic fluid to the pressure supplied from the device.

7. A method according to claim 5 wherein the step of reducing the boost comprises reducing the pressure of the hydraulic fluid to a pressure below the pressure otherwise supplied from the device.