GB1585562A

GB1585562A - Braking system

Info

Publication number: GB1585562A
Application number: GB2171477A
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: DE2723396A1; SE7605861L; DE2723396C2; PT66577A; BE854932A; GB1585563A; JPS52148779A; SU1373308A3; BR7703306A; MX144393A; IT1082093B; JPS6150817B2; PL198373A1; FR2352697A1; AR215003A1; PT66577B; SE419427B; PL134253B1; AU513895B2; CA1084561A

Description

(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. Whilst 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; an operator actuated master cylinder for applying fluid pressure to said brake; a booster operated in response to actuation of said master cylinder for imposing an increase in the fluid pressure applied to said brake to a pressure higher than the pressure applied by said operator actuated master cylinder when operated without the booster; said booster comprising a diaphragm operatively connected to said operator actuated master cylinder, and means for controllably subjecting said diaphragm to a fluid pressure differential thereacross, which include a conduit connecting a chamber defined on one side of said diaphragm to a source of fluid at a predetermined pressure. as herein defined; a sensor for signalling the occurrence of an excessive rate of retardation of the braked rotating 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 said booster, said booster spoiler comprising a valve assembly connected in said conduit connecting said chamber to said source, said valve assembly including valve means, operable in response to a signal from said sensor to seal said chamber from said source and to connect said chamber to a passage including a presct adjustable valve so that the fluid pressure differential across the said diaphragm is reduced at a predetermined rate.

It is to be understood that in this specification the term "a source of fluid at a pre determined pressure" includes à source of fluid at a pressure higher than atmospheric pressure, and a source of fluid at a pressure lower than atmospheric pressure, such as a source of vacuum or partial vacuum.

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 partly schematic, partly sectional view of a braking arrangement in accordance with the present invention incorporating a pneumatic vacuum booster; FIGURE 2 is a view similar to Figure 1, showing a braking arrangement incorporating one form of brake modulator; 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 large air flow volumes.

Referring now more particularly to Figure 1 of the accompanying drawings, a braking arrangement for a rotating member is installed in an automotive vehicle. Such an automotive vehicle (not shown) is equipped with fluid pressure actuated brake means 10 for slowing the vehicle wheels. Operator actuated means in the form of a hydraulic fluid master cylinder indicated at 11, are provided for imposing fluid pressure on the brake means. The master cylinder 11 has operatively connected therewith booster means 12 for increasing the fluid pressure imposed on the brake means 10 to a pressure higher than the pressure imposed solely by the action of the human operator.The booster means takes the form of a vacuum actuated diaphragm means generally indicated at 12. and operatively connected with the master cylinder 11 and being responsive thereto for exertion of a fluid pressure differential across a diaphragm. Such vacuum actuated boosters for power brake systems are generally well known to persons skilled in the arts of 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 arrangements.

By means of a conduit generally indicated at 14 and extending between the diaphragm means 12 and an appropriate source of vac uum. such as the inlet manifold of an internal combustion engine. provision is made for controllably subjecting the diaphragm means 12 to a fluid pressure differential thereac ross. in a manner generally known to approp riately 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 means 12 to a differential between atmospheric pressure and a pressure less than atmospheric, it is also known to persons skilled in the applicable arts to employ a differential pressure means which comprises a compressed air means for subjecting a diaphragm means to a differential between atmospheric pressure and a pressure greater than atmospheric. While this invention will be described hereinafter first with reference to a vacuum actuated diaphragm means 12, it is intended that this invention have applicability to all such variations and forms of power brakes.

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 means 15 is thus operatively 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 includes sensor means 16 for signalling the occurrence of an excessive rate of retardation of a braked rotating vehicle wheel. The sensor means 16 includes electrical switch means for electrically signalling occurrences of an excessive rate of retardation by emitting a signal via appropriate conductors 17. The sensor means 16 for electrically signalling the occurrence of an excessive rate of retardation of a braked rotating member such as an automotive vehicle wheel, are known to 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 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. The sensors there shown or others known to skilled persons may be used in the arrangement of the present invention. Certain such sensors will be understood as signalling occurrences of wheel slip and are, for purposes of this description, deemed comparable to sensors signalling excessive rates of retardation.

The booster spoiler means 15 incorporates valve means which is operatively connected with the diaphragm means 12 and which is responsive to the sensor means 16 for at least relieving the fluid pressure differential exerted by the diaphragm means 12. The valve means shown in Figure 1. is suitable for vacuum actuated diaphragms of relatively small size such as are found on lightweight passengcr automobiles. and comprises a valve spool or spindle 18 mounted within a housing 1 9 for movement relative thereto.

The spindle 18 has mounted thereon a pair of valve discs 20. 21, each of which co-operates with a corresponding valve seat 22, 23. The valve 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 other disc 20 and its co-operating seat 22 controllably opens communication between the 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 way that seating of one disc requires that the other disc be unseated.

A biasing spring 25 normally urges the disc 20 into seating engagement with 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 controlled by a winding 28 and a co-operating core or armature 29. The winding 28 is electrically connected with the conductors 17 from the sensor means 16. for energization by an electrical signal indicative of an occurrence of an excessive rate of retardation of a braked wheel. Energization of the winding 28 causes the armature 29. spindle 18 and discs 20. 21 to be moved (upwardly in Figure 1) against the force of the spring 25. The normally unseated disc 21 is thus 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 diminishment of the booster effect and to prevent accidental entry into the housing 19 of foreign matter, a check valve generally indicated at 3 1 is interposed between the atmosphere and the vent passageway 30. The check valve 3 1 includes a valve member 32 movable relative to an inlet passageway 34 against the bias of a regulating spring 35 as far as a stop member 36. Threaded adjustment members 38, 39 are provided to allow adjustment of 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 permitted in the diaphragm means.By regulation of the force exerted by the spring 35 and the extent to which the vent passageway may open the rate and degree of diminishment of braking effort achieved may be controllcd.

A second embodiment of a braking arrangement which incorporates a modulator is shown in Figure 2. where one specific form of modulator is indicated generally at 50. As shown. the modulator 50. is of a type described in U.K. Patent application No. 6467/76. (Serial No. 15444437).

The structure of the modulator 50 and its function will be made more clear from that description, which is hereby incorporated by reference to any extent necessary to understanding of this invention, but persons skilled in the appropriate arts will know of other forms of modulators and understand their use in braking arrangements according to this invention Elements of the arrangement according to Figure 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 in detail.

It will be noted that the modulator 50 operates in response to a signal from the sensor 16a, as does the booster spoiler 15a.

Most conveniently, energization of the modulator 50 and booster spoiler 15a may occur simultaneously, but it is contemplated that variations in sensor construction and/or electrical circuitry may permit energization of the modulator 50 and booster spoiler 15a at any predetermined time relative to one another after the sensing of an excessive rate of wheel retardation by the sensor 16a.

Figure 3 illustrates another embodiment of a braking arrangement in which a pneumatic compressed air type of booster 12b is utilized compressed air being supplied thereto from an engine driven compressor indicated generally at 5 1. Elements of Figure 3 corresponding to elements shown in Figures 1 and 2 have been identified by similar reference characters followed by the letter b and the description of those elements will not be here repeated.

A modified form of booster spoiler 115 which is usable with pneumatic boosters having relatively large diaphragm areas is illustrated in Figure 4. where components corresponding to components described above with reference to Figure 1 are identified by like reference characters prefixed by the digit 1. The distinction between the booster spoiler 1 5 of Figure 1 and the booster spoiler 115 of Figure 4 is that the winding 128 and armature 1 29 of the booster spoiler 115 controls a pilot valve spindle 1 18 which operates a servo valve which includes a spindle 140 which carries discs 141. 142 for co-operating with respective seats 144. 145. The servo valve is operated by the same vacuum source which supplies the vacuum boost for the vehicle brake system.The operation of the servo controlled booster spoiler 115 is substantially similar to the operation of the directly actuated booster spoiler 15 described hercinabove.

As will be apprcciated. energization of the winding 128 causes the armature 129 to shift against the action of the return spring 125.

moving the spindle 11 8 within the housing 119 so as to seat the disc. 121 against its seat 123 and to remove the disc 120 from its seat 122. The central passageway between the two seats 122 and 123 will thus be sealed from its normal communication with the atmosphere and the reduced pressure present in the conduit 114 will be admitted to a space 146 above a membrane or diaphragm 148 which has its lower surface exposed to atmospheric pressure. The resultant pressure differential across the membrane or diaphragm 148 will shift the servo spindle 140 upwardly against the action of a return spring thereby to seat the disc 142 against its corresponding seat 145 and to remove the disc 141 from its seat 144.With such shifting of seating of the servo valve discs, that portion of the conduit 114 leading to the booster diaphragm means (not shown) is vented to the atmosphere via the channel 130.

In the form illustrated in Figure 4, a valve member 132 is mounted on an adjustable member 138 for controllable positioning relative to an inlet passageway 134. As will be appreciated, adjustment of position of the valve member 132 relative to the inlet passageway 134 will vary the rate at which the increase in braking force obtained through use of the booster is diminished by operation of the booster spoiler 115.

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 arrangements 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.

WHAT WE CLAIM IS: 1. A braking arrangement for braking a rotating member comprising a fluid pressure actuated brake for slowing the rotating member; an operator actuated master cylinder for applying fluid pressure to said brake; a booster operated in response to actuation of said master cylinder for imposing an increase in the fluid pressure applied to said brake to a pressure higher than the pressure applied by said operator actuated master cylinder when operated without the booster; said booster comprising a diaphragm operatively connected to said operator actuated master cylinder, and means for controllably subjecting said diaphragm to a fluid pressure differential there across, which include a conduit connecting a chamber defined on one side of said diaphragm to a source of fluid at a pfedetermined pressure, as herein defined; a sensor for signalling the occurrence of an excessive rate of retardation of the braked rotating 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 said booster, said booster spoiler comprising a valve assembly connected in said conduit connecting said chamber to said source, said valve assembly including valve means, operable in response to a signal from said sensor to seal said chamber from said source and to connect said chamber to a passage including a preset adjustable valve so that the fluid pressure differential across the said diaphragm is reduced at a predetermined rate.

2. A braking arrangement according to claim I wherein said sensor comprises an electrical switch for electrically signalling the occurrence of an excessive rate of retardation of the rotating member and wherein said valve assembly comprises a solenoid actuated valve.

3. A braking arrangement according to claim I or claim 2 wherein said source of fluid at a predetermined pressure comprises a source of vacuum or partial vacuum so that said diaphragm is subjected to a differential between atmospheric pressure and a pressure less than atmospheric pressure.

4. A braking arrangement according to claim I or claim 2 wherein said source of fluid at a predetermined pressure comprises a source of compressed air, the arrangement being such that said diaphragm is subjected to a differential between atmospheric pressure and a pressure greater than atmospheric pressurc.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

123 and to remove the disc 120 from its seat 122. The central passageway between the two seats 122 and 123 will thus be sealed from its normal communication with the atmosphere and the reduced pressure present in the conduit 114 will be admitted to a space 146 above a membrane or diaphragm 148 which has its lower surface exposed to atmospheric pressure. The resultant pressure differential across the membrane or diaphragm 148 will shift the servo spindle 140 upwardly against the action of a return spring thereby to seat the disc 142 against its corresponding seat 145 and to remove the disc 141 from its seat 144. With such shifting of seating of the servo valve discs, that portion of the conduit 114 leading to the booster diaphragm means (not shown) is vented to the atmosphere via the channel 130.

In the form illustrated in Figure 4, a valve member 132 is mounted on an adjustable member 138 for controllable positioning relative to an inlet passageway 134. As will be appreciated, adjustment of position of the valve member 132 relative to the inlet passageway 134 will vary the rate at which the increase in braking force obtained through use of the booster is diminished by operation of the booster spoiler 115.

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 arrangements 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.

WHAT WE CLAIM IS: 1. A braking arrangement for braking a rotating member comprising a fluid pressure actuated brake for slowing the rotating member; an operator actuated master cylinder for applying fluid pressure to said brake; a booster operated in response to actuation of said master cylinder for imposing an increase in the fluid pressure applied to said brake to a pressure higher than the pressure applied by said operator actuated master cylinder when operated without the booster; said booster comprising a diaphragm operatively connected to said operator actuated master cylinder, and means for controllably subjecting said diaphragm to a fluid pressure differential there across, which include a conduit connecting a chamber defined on one side of said diaphragm to a source of fluid at a pfedetermined pressure, as herein defined; a sensor for signalling the occurrence of an excessive rate of retardation of the braked rotating 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 said booster, said booster spoiler comprising a valve assembly connected in said conduit connecting said chamber to said source, said valve assembly including valve means, operable in response to a signal from said sensor to seal said chamber from said source and to connect said chamber to a passage including a preset adjustable valve so that the fluid pressure differential across the said diaphragm is reduced at a predetermined rate.
2. A braking arrangement according to claim I wherein said sensor comprises an electrical switch for electrically signalling the occurrence of an excessive rate of retardation of the rotating member and wherein said valve assembly comprises a solenoid actuated valve.
3. A braking arrangement according to claim I or claim 2 wherein said source of fluid at a predetermined pressure comprises a source of vacuum or partial vacuum so that said diaphragm is subjected to a differential between atmospheric pressure and a pressure less than atmospheric pressure.
4. A braking arrangement according to claim I or claim 2 wherein said source of fluid at a predetermined pressure comprises a source of compressed air, the arrangement being such that said diaphragm is subjected to a differential between atmospheric pressure and a pressure greater than atmospheric pressurc.
5. A braking arrangement according to

any one of the preceding claims wherein said valve assembly comprises a valve spindle having two valve discs thereon, the spindle being movable between a first position in which a first disc engages a first seat and a second position in which a second disc engages a second seat, the arrangement being such that when the spindle is in the first position the conduit between the said source and said chamber is open and when the spindle is in the second position this conduit is sealed, but the portion of the conduit connected to the said chamber is connected to said preset adjustable valve.
6. A braking arrangement according to claim 5 wherein said spindle is directly connected to a member located within and movable in response to signals supplied to an electro-magnet.
7. A braking arrangement according to claim 5 wherein said spindle is connected to a diaphragm and a solenoid operated pilot valve is provided which, on actuation, connects a chamber formed on one side of the diaphragm connected to the spindle to a source of vacuum or partial vacuum causing movement of the diaphragm and consequent movement of said spindle.
8. A braking arrangement according to any one of the preceding claims wherein a brake modulator is provided in a conduit connected between said master cylinder and said brake 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.
9. A braking arrangement substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings.
10. A braking arrangement substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.
I I. A braking arrangement substantially as herein described with reference to and as shown in Figure 3 of the accompanying drawings.
12. A braking arrangement substantially as herein described with reference to and as shown in Figures 1. 2 or 3 as modified by Figure 4 of the accompanying drawings.
13. An automotive vehicle when provided with a braking arrangement according to any one of the preceding claims.