CA1180038A - Vehicle hydraulic brake system and apparatus - Google Patents
Vehicle hydraulic brake system and apparatusInfo
- Publication number
- CA1180038A CA1180038A CA000375136A CA375136A CA1180038A CA 1180038 A CA1180038 A CA 1180038A CA 000375136 A CA000375136 A CA 000375136A CA 375136 A CA375136 A CA 375136A CA 1180038 A CA1180038 A CA 1180038A
- Authority
- CA
- Canada
- Prior art keywords
- cam
- valve
- piston
- vehicle
- shaft
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/18—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 vehicle weight or load, e.g. load distribution
- B60T8/1837—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 vehicle weight or load, e.g. load distribution characterised by the load-detecting arrangements
- B60T8/185—Arrangements for detecting vehicle level
-
- 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
- B60T11/00—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant
- B60T11/10—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant transmitting by fluid means, e.g. hydraulic
- B60T11/28—Valves specially adapted therefor
- B60T11/34—Pressure reducing or limiting valves
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Hydraulic Control Valves For Brake Systems (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A proportioning valve for a vehicle hydraulic brake system has a lock out mechanism whereby the valve may be selectively rendered inoperative for given vehicle load con-ditions. The valve has a piston responsive to hydraulic pres-sure, for operating the valve, a rotatable cam having a cam profile communicating with the piston, a rotatable shaft and a coupling between the cam and the shaft whereby rotation of the shaft, in response to vehicle load conditions, effects rotation of the cam, the cam profile being configured to impede movement of the piston when the cam is rotated to a given angular position, thereby locking the valve in an in-operative configuration.
A proportioning valve for a vehicle hydraulic brake system has a lock out mechanism whereby the valve may be selectively rendered inoperative for given vehicle load con-ditions. The valve has a piston responsive to hydraulic pres-sure, for operating the valve, a rotatable cam having a cam profile communicating with the piston, a rotatable shaft and a coupling between the cam and the shaft whereby rotation of the shaft, in response to vehicle load conditions, effects rotation of the cam, the cam profile being configured to impede movement of the piston when the cam is rotated to a given angular position, thereby locking the valve in an in-operative configuration.
Description
003~
The present invention relates to a propor-tioning valve ~or a load sensing hydraulic brake pressure control apparatus for use in the hydraulic circuit be-tween the master cylinder and the rear wheel brake cylinders. The apparatus is adapted for sensing varia-tions in the distance between the vehicle chassis and the suspended axle shaft.
It is known that changes in vehicle loading cause changes in braking capability. For example, when a vehicle is fully loaded, the rear wheels will have nearly the same braking capability as the front wheels.
However, when the vehicle is lightly loaded, the rear wheels may exhibit less braking capability than the front wheels. Thus the potential for premature rear wheel lock up is much greater when stopping the lightly loaded vehicle than when stopping the fully loaded vehicle.
In order to compensate for the inherent imbalance be-tween front ancl rear braking action/ it has been cus-tomary in past years to provide a proportioning valve which restric-ts fluid com~unication to the rear wheel brake cylinders after a predetermined pressure level is generated. However, such proportioning valves repre-sent a compromise between the desirable system char-ackeristlcs Eor the ~ull loacl concli.tion and those ~OL' ~he lLg}lt load condi-~ion, Thus the selected propor--tionin~ valve chLIracteristlc is neither suitable Eor -the fuLL load conclLtion nor ~he lLght lo~cl condLtion.
Many load sensing or vehicle heigh-t sensirlg va:Lve mech-anlsms have here-to~ore bee`n presented in the prior art.
However, they are unnecessarily complex or otherwise g~s ~g ~ ~8~38 unsui-table for modern vehicle use. For example, see U.S. Patents: 3/362,758; 3,503,657; 3,649,08~; 3,68~,329;
3,734,57~; 3,768,876; 3,848,932; ~150,855 and 4,159,855.
It is an object of the present invention to provide a novel and improved proportioning valve for use in a vehicle hydraulic brake system.
According to the invention there is provided a proportioning valve for a vehicle hydraulic brake sys-tem having a lock out mechanism whereby the valve may be selectively rendered inoperative for given vehicle load conditions which comprises valve means including piston means responsive to hydraulic pressure for opera-ting the valve means; rotatable cam means having a cam profile communicating with the pis-ton means, a rotatable shaft, coupling means between the cam means and the shaft whereby rotation of the shaft effects rotation of the cam means, the cam profile being configured to impede movement of the piston means when the cam means is rotated to a given angular piston thereby locking the valve means in an inoperative eonfiguration, and means for rotatincJ the rotatable sha:et in respons~ to vehicle load concllt:Lons~
~ re~e.rahly, the rotatabl.e cam means include~
stop means whereb~ the ancJle O:e rotation of the CaM
mean~ is limitecl -to a pxedetexmined are.
In use, the proportionincJ valve may be ric3iclly attaehed to a vehicle frame and the cam is driven by mechanical l.inkage attached to the vehicle a~le. As the vehicle is loaded compression of the suspension , 3 ~
system reduces the distance between the vehicle frame and the axle. The mechanical linkage in response to -the reduction in distance rotates the digital cam to a position whereby the proportioning valve is disabled.
Thus pressure may be passed undisturbed through the proportioning valve to the rear wheel brakes.
In a preferred embodiment, the cam is rota-tingly seated upon the shaft so as to allow relative rotation therebetween. A torsional spring affixed to the cam has one leg anchore~ thereon and the other leg engaging a flat diametric camming surface provided in the shaft. Thus -the cam is caused to rotate in concert with the shaft. However, by reason of the torsion spring a unique drive mechanism is provided which ac-commodates relative motion between the vehicle frame and the axle during vehicle operation by permitting rela-tive rotation between the cam and the shaft whenever rotation of the cam is restricted by the functional operation of the proportioning valve.
Although the proportioning valve is herein-after described as being in series with ano-ther propor-tl.onillg valve assembly, i~ is to be unders-tood that -the present valv~ may be used aLone in systems where a mas~r cyLincler output pre~sure is suitable, wi-thout an lnterverl;Ln~ proportlonal valve, ~or dlrect tran~mission to -the vehlcle bralces in the heavily loaded condition.
~mbodiments of the invention will now be described with reexence to -the accompanying drawings, in which:
Figure 1 is a schematic view of a hydraulic 0 3 ~
brake system incorporating a load sensing proportioning valve embodying the present invention.
Figure 2 is a graphical illustration of the performance of a brake proportioning system.
Figure 3 pictoria:Lly depic-ts a typical vehicle installation of a load sensLng propor-tioning valve em-bodying the present invention.
Eigure 4 is a par~ial cross-sectional view of the load sensing proport.ioning valve used in the braking system illustrated .in Figure 1.
Figure 5 is a cro:s-sectional view taken along line 5-5 in Figure 4.
Figure 6 is a par-tial cross-sectional view taken along li.ne 6~6 in Figure 4.
Figure 7 is a partial cross-sectional view taken along line 7-7 in Figure 4.
Figure 8 is an exploded pictorial view showing the assembly of elements co1.nprising the cligital cam portion of the load sensing proportioning valve.
Figure 9 is an isl~lated pictorial view of the dic~ital cam rotated 180 :Erl~m that shown i.n Figure 8.
Fl~ure 10 is a sc:hemat:Lc :Lllustration of the load sen~:lnc3 proport:Lonlnc3 valve conficJuration when the vehicle ls llghtly loaded.
Figu:re 11 Ls a sc:hematic :I.ll.ustration oE the loacl sensinc3 proportioning valve configuration when the vehicle is heavily loaded.
Figures 12 and 13 present schematic illustra-tions of load sensi.ng proportioning valve configura-tions ~.
3 ~L~0~3~
accommodating over-rotation o-f -the digital cam drive-shaf-t.
Figure 14 presents a partial cross-sectional view of the load sensing propor-tioning valve, similar to that of Figure 6, wherein -the digital cam mechani.sm is configured activa-tion by clockwise rotation of the digital cam driveshaft.
Referring to the drawings a vehicle hydraulic braking sys-tem is shown in Figure 1. Mas-ter cylinder 11 provides brake activating hydraulic fluid pressure by means of conduit F to the vehicle front wheel brakes 13L, and 13R first passing through a me-tering valve assembly, not shown, contained in combination valve 12.
Conduit R similarly provides an independen-t source of brake activating hydraulic fluid pressure to a ~irst proportioning valve assembly 14, shown schematically in combination valve 12, for supply to the vehicle rear wheel brakes 15L, and 15R.
Proportioning valve 11 may be of any design ,,20 known, to the art, such as shown in U.S. Patent 3,423,936, having a sing].e spllt po:lnt relationsh:lp between input hyd.raulic pressure and output h~draul:Lc pressure. ',rhe ,.. 6 0 3 ~
propor~ioning valve 14 is designed to produce an output pressure relationship to input pressure as shown in Figure 2 and identified as "LOAD~D". The split point at which valve 14 begins proportioning being indica-ted as point L. The curve identified as "LOADED'7 in Figure 2 represents a master cylinder to rear brake pressure relationship acceptable for a vehicle loaded beyond a given mid-load condition and up to its full gross vehicle weight (GVW). The output hydraulie fluid pressure from proportioning valve 1~ is -transmitted to the vehicle rear brakes by conduits Rl and R2 passing through load sensing proportioning valve (LSPV) device 20.
LSPV 20 ineludes a seeond propor.tioning valve assembly 16, hereinafter deseribed in greater detail, having a similar eonstruetion as that of proportioning valve assembly 14 eontained in eombination valve 12. Proportioning valve assembly 16, when permitted to function, operates upon the output hydraulie pressure reeeived from propor-tioning valve 14 sueh that the relationship between master eylinder pressure (input to proportioning valve 14) to rear brake pressure (output from proportioning valve 16) is represented by the eurve identified as "EMPTY" in Figure 2. The "EMPTY" eurve shown in Figure 2 represents a ma.ster cyli.nder to rear bra~e pressure :rela~ion~hlp acceptable ~or a vehicle load cond.it1.on ~allincJ below the selected mid-load condition.
A dicJital cam mechan:ism 25 ls provi.cled wlthin l,SPV 20 to selectively disable proport:ionincJ va:Lve assembly 16 in the ~ull open configuration when the vehicle is he.avi:Ly loaded. Thus when the vehlcle .is loadecl beyoncl the seleeted mid-load eondition, proportionin~ valve 1~ is di.sabled by acti.on Oe cligital eam ~5 thereby perr.litting, undisturbed, -the transmission of hyclraulie pressure -therethrough and resulting in the desired "LOADED"
pressure rela-tionship shown in Figure 2. However, when the vehicle is ligh-tly loaded proportioning valves 1~ and 16 function in series and produce a master cylinder pressure to rear brake pressure relationship as indica-ted by the curve "EMP~Y" in Figure 2.
Figure 3 pictorially depicts a -typical vehicle installation o tlhe load sensing proportioning valve. LSPV 20 is rigidly affixed to a non-suspende~ portion of the vehicle frame 35. Driveshaft 50 is firmly attached to linkage 30 so that as linkage 30 rotates driveshaft 50 rotates digital cam 25 by a drive mechanism hereinafter described in greater detail.
Linkage 30 is firmly a-ttached to the vehicle axle tube 31 or any other suitable element of the suspended portion of the rear wheel assembly.
Digi-tal cam 25, through action of linkage 30 attached to vehicle axle 31 responds to compression or expansion o~ the vehicle suspension system (not shown). When -the linkage is extended the vehicle is lightly loaded and propor-tioning valve 16 is pexmi-tted -to function. However, when -the l:i.nkacJe is compressed the vehicle i5 heav:Lly Joaded and cllgitaL cam 25 LS rota~ecl into posLtLon so aS to dLsab:Le the operat:Lon Oe -tlle proport:LonLncJ valve 16.
ReEerring to Figure 5,proportioning valve assembly 16 as shown and described herein is merely represent:ative oE known propor-t:ioning valve mechanis~s. Recogni~ing -that any ~nown proportioning valve mechanism whlch may be modi:Led to ~unct;ion as herein described i.5 SUi table ~or use wLth the present invention, the opera-tion ., , 0 3 ~
of proportioning valve assemb'y 16 will be described only to the extent necessary to understand its interrelationship with my digital cam and its function with respect to the overall brake hydraulic system.
Proportioning valve assembly 16 comprises valve piston 40 positioned axially within bore 45 and extending into bore 45a of smaller diameter which in turn opens into digital cam cavity 70.
O-ring seal 47 is provided to hydraulically seal bore ~5 from bore 45a thereby preventing the ~low of hydraulic fluid into bore 45a. Piston 40 is provided with a pin like extension 48 projecting into bore 49. Piston 40 is permitted to axially translate within bore 45a so that pin 48 may project in~o the digital cam cavity 70 as will be described hereinafter.
The opposite end of piston 40, includes valve head 43 which is less in diameter than that of bore 45b thus permitting the unrestricted flow o~ hydraulic fluid thereby. Piston 40 is further provided extension cap 41 having notch 42 therein.
Piston 40 is normally biased to the left by action of spring 46 such that extension 41 is urged abuttingly against the end of bore 45b. Hydra~ulic fluid is thus permitted to enter inlet por-t Rl, ~xeely pass between piston 40 ancl eJastomeric valve seat 4~, past valve head 43, throu~h notch 42 and exit -throucJh outle-t port R2. Thus in the con~:icJuratiorl as shown in Figure 5 the 1uid pressure at outLet por-t R2 will be ec~ual to -the ~lu:id press~lrc at inlet port Rl.
During brake application the above describecl ~luid path throucJh proportioning valve 16 remains open until the fluid pressure delivered at inlet port Rl a-ttains a precletexmined level. ~t this time valve head 43 will close against valve seat 44. The level of pressure at which this occurs is depenclent ~ ~80~3~
upon -the force of spr:ing 46 as compared to the effective area of -the valve piston 40, acted upon by inlet fluid pressure in a direction opposing the force of spring 46~ This effective area is equal to the diameter D of piston 40 since the right hand end of piston 40 projec-ting into bore 45a is sealed oEf rom the inlet fluid pressure by O-ring seal 47 while the inlet fluid pressure acts against all of the remaining portions of piston 40.
After valve head ~13 closes against valve seat 44 and the fluid pressure at inlet port ~1 is further increased, the increased pressure will act against piston 40 over an effective circular area having a diameter equal to the main sealing diameter of valve head 43 less the cross-sectional area of piston 40 extending into bore 45a. This produces a force acting upon piston 40 in the same direction as an assisting spring 46 to reopen valve head 43 so as to deliver at least a portion of the increased fluid pressure to outlet port R2O However, any increased fluid pressure delivered to ou-tlet port R2 creates an opposing force upon piston 40. The opposing force tends to reclose valve head 43 against valve seat 44. The opposing forces tend to keep valve head 43 closely adjacent to valve seat ~4 thereby xestricting the flow of fluid from inlet por-t Rl to outle~ port R2 creatiny a pressure a-t the outlet port R2 which increases at a lower rate than the pressure at inl.et port Rl.
rrhe rat.io Oe the~ pressure.s is determined by the re:Lationship of the effcctlve area~s previoLIs:Ly reeerred -to and hellce the fluid pressure passincJ throuyh proportioning valve 16 rilay be propor tioned -to Eollow a precletermined relationship.
During tha-t portion of a brake application in which the app~ied pedal eEort is reduced subsequent to a brake application of su:~ficien-t intensity to have moved piston ~0 -to the restricted v ~ ~
flow positionthe forces tencling -to move piston ~0 -to the le~t are reduced and piston 40 translates to the righ-t under -the influence of the pressure at outlet port R2. As -the piston 40 moves right valve head ~3 is permitted to slide within the inner peripheral surface of valve seat 44, -thereby increasing the available volume for the fluid at the rear brake cylinders 15L
and 15R and accomplishin~ a reduction in pressure at outlet port R2. The pressure at outlet port R2 can never be greater than the pressure at inlet port Rl because valve seat 44 also acts as a fluid check valve permitting the flow of fluid from port R2 and into bore 45.
For a more detailed description relating -to propor-tioning valve operation and the clesign of particular propor~
tioning valve elements refer to U. S. Patent No. 3,423,936 issued to William Stelzer on January 28, 1969.
Figures ~ through 9 are to be referred to for the following description of the digital cam 25, its construction and operation. LSPV housing 19 is provided with a two step bore 60. FLoor 69 of bore 60 contains recessed therein semicircular slot 67 and journal recess 68. Cam driveshaft 50 is supported and re-tained as shown in Figure 4. Journal 51 of drivesllaE~ 50 is ro-tat:ionally recelved within journal recess 68. Sha~t 50 extencls generally normal -to bore floor 69 passincJ
through ancl rotationally supported by end cap 61. End cap 6:L
is ~n~lgly rctaLnecl within bore 60a ancl against shoulder 62 by action o~ snap rincJ 63. O-x;ing 55 is provided to seal the dig:ital cam chamber 70 erom the entrance of any contamlnation thereto. Cam driveshaft 50 protrudes externally of end cap 61 s~lEficiently -to permit rigicl engacJement thereo~ by linkage 30 (see Figure 3). Thus driveshaft 50 is caused to rota!e -through the same angular clisplacement as that of linkage 30~
~ ~8~3~
Digital carn 25 is rotationally supportecl on cam journal 52 of driveshaft 50 such that cam 25 may rotate relative to driveshaEt 50. Cam 25 is provided with a periph~ral recess 26 and axially ciirected knurls ~4 over a-t leas-t the working peripheral por-tion of cam 25. The working portion of cam 25 will become apparent as the function and operation are further described hereinafter. Pin 32 projects axially from cam 25 into and slidably engaging slo-t 67 in bore floor 69 -thereby lirniting the angular rotation of cam 25 to that are inscribed by slot 67. The inboard side 22 of cam 25 is milled providing inboard facing stepped surface 27. Circular recess 21 extends axially through cam 25 from the outboard surface 28 and slightly past the inboard facing stepped surface 27 thereby providing passageway 23 between outboard surface 28 and inboard surface 27. Mandrel 33 is axia]ly positioned within circular recess 21 extending outboard and slightly past outboard surface 28.
Torsion spring 34 is seated about mandrel 33,the helical portlon thereof being seated within circular recess 21 such that inboard leg 34a extends through passage way 23 in juxta-posed relation with inboard facing stepped surface 27 and enc~ages spring retention hole 29. Outboard spring leg 34b extends in juxtaposecl relation with outboard surface 2~ oE
aam 25 e~ten~ing irlto slot 54 of driveshaft 50 and engac3ing the flat cammlng surface 53. In thelr normal assembled sta-te as here:inabove described and shown in ~'igure 6, torsion spring legs 34a and 34b are spring loadecl so as to apply an angularly outward force upon sprinc~ retention hole 29 and the flat camming surEace 53 of clriveshaft 50. Slot 56 is provicled at the external and outboard end of car,~ driveshaft 50 to permit external adjustment~
~ 12 -. . ~
0 3 ~
In opera-tion cam 25 is caused to ro-tate with cam driveshaft 50 by reason of torsion spring 34 applyir.g spriny force upon cammincj surface 53 of shaft 50. However, should cam 25 be restricted from rotating because of interference between pin 32 and slot 67 or because of interference between cam 25 and pin 48 on valve pis-ton 40, cam driveshaft 50 may however, rotate relative to canl 25 by further compressing torsion spring 34. Thus, a spring drive mechanism is provided between cam driveshaft 50 and diyital cam 25 which allows :Eor over travel of shaft 50 when rotation of cam 25 is otherwise restricted.
Figures 3/ 5 through 7 and 10 depict the configuration of LSPV 20 under conditions of light vehicle loading. The vehicle frame 35 ls riding relatively high with respect to suspended axle 31. Thus linkage 30 positions digital cam 25 such that peripheral recess 26 permits pin 48 of piston 40 to axially translate in and out of digital cam chamber 70.
Proportioning valve 16 is permitted to freely function resulting in a master cylinder pressure to rear brake pressure rela-tionship as shown by the curve identified as "EMPTY" in rigure 2.
So long as the vehicle is lightly loaded proportioning valve 16 is function. Peripheral slot 26 accommodates operati.on of valve 16. IIowever, shoulcl valve piston pin ~8 protrude into cam chamher 70 a~l a result of vehicle braking aIld the vehicle encountered an e~treme roacl concli-tion cau.sing cam drives~af-t 50 to momentari.ly, over rotate ~rom excessi.ve compres~:ion o:~ the veh:icle suspension system, cam ~5 w.ill momentarily encJag~ valve piStOII pin ~ stopping khe camls counterclockw:Lse rok-lt.ion.
Iloweve.r, cam clriveshaft S0 is permiktecl to continu~ .its counter--c:Lockwise rotation by compression torsion spring 34. Such a condition :is illustratecl in Eigure 13.
1 ~3~
When the vehicle is loaded heavy the suspension system is compressed such that the vertical separation between frame 35 and axle 31 is reduced. Linkage 30 assu~es a configu~ation as depic-ted in Figure 11 thereby rotating digital cam 25 counterclockwise as shown. In this configuration the outermost periphery of cam 25 is rotated in a position that disables proportioning valve 16 by preventing the free translation piston 40. Thus in the loaded condition, as illustra-ted in Figure 11, the master eylinder pressure to rear brake pressure relationship is as shown by the curve identified as "LOADED" in Figure 2.
So long as the vehiele is in the loaded eondition the outer periphery of cam 25 will remain in the valve piston disabling configuration as illustrated in Figures ll and 12. In this configuration and when the applied braking load is such that valve piston 40 attempts to translate to the right valve piston pin 48 buts against cam 25 and engages the axial knurls 24 on the outer periphery of eam 25. Thus cam 25 is restricted from freely rotating. Any fur-ther rotation of cam driveshaft 50 resulting from road indueed vacillations of axle 31 wil.l be aeeofnmodated by eompression of tors.ion spring 34 as illustrated in Figure 12~
The angle A (Figure 6) between the pin 48 centerline and digital eam step 26a determines the vehicle load condition at whieh proporti.oning valve 16 is disabled therefore it is necessary that this ancJle be aeeurately fixed. Anc31e A i~
detexlni.ned for an unloaded vehicle ancl represents that angle throucJh wh.ich driveshaf-t 50 wi:ll rotate as the vehicle is loaded to that mid-loacl condition at which it is desi.red to ehange from -the "EMPTY" curve -to the "LOADED" curve as shown in Figure
The present invention relates to a propor-tioning valve ~or a load sensing hydraulic brake pressure control apparatus for use in the hydraulic circuit be-tween the master cylinder and the rear wheel brake cylinders. The apparatus is adapted for sensing varia-tions in the distance between the vehicle chassis and the suspended axle shaft.
It is known that changes in vehicle loading cause changes in braking capability. For example, when a vehicle is fully loaded, the rear wheels will have nearly the same braking capability as the front wheels.
However, when the vehicle is lightly loaded, the rear wheels may exhibit less braking capability than the front wheels. Thus the potential for premature rear wheel lock up is much greater when stopping the lightly loaded vehicle than when stopping the fully loaded vehicle.
In order to compensate for the inherent imbalance be-tween front ancl rear braking action/ it has been cus-tomary in past years to provide a proportioning valve which restric-ts fluid com~unication to the rear wheel brake cylinders after a predetermined pressure level is generated. However, such proportioning valves repre-sent a compromise between the desirable system char-ackeristlcs Eor the ~ull loacl concli.tion and those ~OL' ~he lLg}lt load condi-~ion, Thus the selected propor--tionin~ valve chLIracteristlc is neither suitable Eor -the fuLL load conclLtion nor ~he lLght lo~cl condLtion.
Many load sensing or vehicle heigh-t sensirlg va:Lve mech-anlsms have here-to~ore bee`n presented in the prior art.
However, they are unnecessarily complex or otherwise g~s ~g ~ ~8~38 unsui-table for modern vehicle use. For example, see U.S. Patents: 3/362,758; 3,503,657; 3,649,08~; 3,68~,329;
3,734,57~; 3,768,876; 3,848,932; ~150,855 and 4,159,855.
It is an object of the present invention to provide a novel and improved proportioning valve for use in a vehicle hydraulic brake system.
According to the invention there is provided a proportioning valve for a vehicle hydraulic brake sys-tem having a lock out mechanism whereby the valve may be selectively rendered inoperative for given vehicle load conditions which comprises valve means including piston means responsive to hydraulic pressure for opera-ting the valve means; rotatable cam means having a cam profile communicating with the pis-ton means, a rotatable shaft, coupling means between the cam means and the shaft whereby rotation of the shaft effects rotation of the cam means, the cam profile being configured to impede movement of the piston means when the cam means is rotated to a given angular piston thereby locking the valve means in an inoperative eonfiguration, and means for rotatincJ the rotatable sha:et in respons~ to vehicle load concllt:Lons~
~ re~e.rahly, the rotatabl.e cam means include~
stop means whereb~ the ancJle O:e rotation of the CaM
mean~ is limitecl -to a pxedetexmined are.
In use, the proportionincJ valve may be ric3iclly attaehed to a vehicle frame and the cam is driven by mechanical l.inkage attached to the vehicle a~le. As the vehicle is loaded compression of the suspension , 3 ~
system reduces the distance between the vehicle frame and the axle. The mechanical linkage in response to -the reduction in distance rotates the digital cam to a position whereby the proportioning valve is disabled.
Thus pressure may be passed undisturbed through the proportioning valve to the rear wheel brakes.
In a preferred embodiment, the cam is rota-tingly seated upon the shaft so as to allow relative rotation therebetween. A torsional spring affixed to the cam has one leg anchore~ thereon and the other leg engaging a flat diametric camming surface provided in the shaft. Thus -the cam is caused to rotate in concert with the shaft. However, by reason of the torsion spring a unique drive mechanism is provided which ac-commodates relative motion between the vehicle frame and the axle during vehicle operation by permitting rela-tive rotation between the cam and the shaft whenever rotation of the cam is restricted by the functional operation of the proportioning valve.
Although the proportioning valve is herein-after described as being in series with ano-ther propor-tl.onillg valve assembly, i~ is to be unders-tood that -the present valv~ may be used aLone in systems where a mas~r cyLincler output pre~sure is suitable, wi-thout an lnterverl;Ln~ proportlonal valve, ~or dlrect tran~mission to -the vehlcle bralces in the heavily loaded condition.
~mbodiments of the invention will now be described with reexence to -the accompanying drawings, in which:
Figure 1 is a schematic view of a hydraulic 0 3 ~
brake system incorporating a load sensing proportioning valve embodying the present invention.
Figure 2 is a graphical illustration of the performance of a brake proportioning system.
Figure 3 pictoria:Lly depic-ts a typical vehicle installation of a load sensLng propor-tioning valve em-bodying the present invention.
Eigure 4 is a par~ial cross-sectional view of the load sensing proport.ioning valve used in the braking system illustrated .in Figure 1.
Figure 5 is a cro:s-sectional view taken along line 5-5 in Figure 4.
Figure 6 is a par-tial cross-sectional view taken along li.ne 6~6 in Figure 4.
Figure 7 is a partial cross-sectional view taken along line 7-7 in Figure 4.
Figure 8 is an exploded pictorial view showing the assembly of elements co1.nprising the cligital cam portion of the load sensing proportioning valve.
Figure 9 is an isl~lated pictorial view of the dic~ital cam rotated 180 :Erl~m that shown i.n Figure 8.
Fl~ure 10 is a sc:hemat:Lc :Lllustration of the load sen~:lnc3 proport:Lonlnc3 valve conficJuration when the vehicle ls llghtly loaded.
Figu:re 11 Ls a sc:hematic :I.ll.ustration oE the loacl sensinc3 proportioning valve configuration when the vehicle is heavily loaded.
Figures 12 and 13 present schematic illustra-tions of load sensi.ng proportioning valve configura-tions ~.
3 ~L~0~3~
accommodating over-rotation o-f -the digital cam drive-shaf-t.
Figure 14 presents a partial cross-sectional view of the load sensing propor-tioning valve, similar to that of Figure 6, wherein -the digital cam mechani.sm is configured activa-tion by clockwise rotation of the digital cam driveshaft.
Referring to the drawings a vehicle hydraulic braking sys-tem is shown in Figure 1. Mas-ter cylinder 11 provides brake activating hydraulic fluid pressure by means of conduit F to the vehicle front wheel brakes 13L, and 13R first passing through a me-tering valve assembly, not shown, contained in combination valve 12.
Conduit R similarly provides an independen-t source of brake activating hydraulic fluid pressure to a ~irst proportioning valve assembly 14, shown schematically in combination valve 12, for supply to the vehicle rear wheel brakes 15L, and 15R.
Proportioning valve 11 may be of any design ,,20 known, to the art, such as shown in U.S. Patent 3,423,936, having a sing].e spllt po:lnt relationsh:lp between input hyd.raulic pressure and output h~draul:Lc pressure. ',rhe ,.. 6 0 3 ~
propor~ioning valve 14 is designed to produce an output pressure relationship to input pressure as shown in Figure 2 and identified as "LOAD~D". The split point at which valve 14 begins proportioning being indica-ted as point L. The curve identified as "LOADED'7 in Figure 2 represents a master cylinder to rear brake pressure relationship acceptable for a vehicle loaded beyond a given mid-load condition and up to its full gross vehicle weight (GVW). The output hydraulie fluid pressure from proportioning valve 1~ is -transmitted to the vehicle rear brakes by conduits Rl and R2 passing through load sensing proportioning valve (LSPV) device 20.
LSPV 20 ineludes a seeond propor.tioning valve assembly 16, hereinafter deseribed in greater detail, having a similar eonstruetion as that of proportioning valve assembly 14 eontained in eombination valve 12. Proportioning valve assembly 16, when permitted to function, operates upon the output hydraulie pressure reeeived from propor-tioning valve 14 sueh that the relationship between master eylinder pressure (input to proportioning valve 14) to rear brake pressure (output from proportioning valve 16) is represented by the eurve identified as "EMPTY" in Figure 2. The "EMPTY" eurve shown in Figure 2 represents a ma.ster cyli.nder to rear bra~e pressure :rela~ion~hlp acceptable ~or a vehicle load cond.it1.on ~allincJ below the selected mid-load condition.
A dicJital cam mechan:ism 25 ls provi.cled wlthin l,SPV 20 to selectively disable proport:ionincJ va:Lve assembly 16 in the ~ull open configuration when the vehicle is he.avi:Ly loaded. Thus when the vehlcle .is loadecl beyoncl the seleeted mid-load eondition, proportionin~ valve 1~ is di.sabled by acti.on Oe cligital eam ~5 thereby perr.litting, undisturbed, -the transmission of hyclraulie pressure -therethrough and resulting in the desired "LOADED"
pressure rela-tionship shown in Figure 2. However, when the vehicle is ligh-tly loaded proportioning valves 1~ and 16 function in series and produce a master cylinder pressure to rear brake pressure relationship as indica-ted by the curve "EMP~Y" in Figure 2.
Figure 3 pictorially depicts a -typical vehicle installation o tlhe load sensing proportioning valve. LSPV 20 is rigidly affixed to a non-suspende~ portion of the vehicle frame 35. Driveshaft 50 is firmly attached to linkage 30 so that as linkage 30 rotates driveshaft 50 rotates digital cam 25 by a drive mechanism hereinafter described in greater detail.
Linkage 30 is firmly a-ttached to the vehicle axle tube 31 or any other suitable element of the suspended portion of the rear wheel assembly.
Digi-tal cam 25, through action of linkage 30 attached to vehicle axle 31 responds to compression or expansion o~ the vehicle suspension system (not shown). When -the linkage is extended the vehicle is lightly loaded and propor-tioning valve 16 is pexmi-tted -to function. However, when -the l:i.nkacJe is compressed the vehicle i5 heav:Lly Joaded and cllgitaL cam 25 LS rota~ecl into posLtLon so aS to dLsab:Le the operat:Lon Oe -tlle proport:LonLncJ valve 16.
ReEerring to Figure 5,proportioning valve assembly 16 as shown and described herein is merely represent:ative oE known propor-t:ioning valve mechanis~s. Recogni~ing -that any ~nown proportioning valve mechanism whlch may be modi:Led to ~unct;ion as herein described i.5 SUi table ~or use wLth the present invention, the opera-tion ., , 0 3 ~
of proportioning valve assemb'y 16 will be described only to the extent necessary to understand its interrelationship with my digital cam and its function with respect to the overall brake hydraulic system.
Proportioning valve assembly 16 comprises valve piston 40 positioned axially within bore 45 and extending into bore 45a of smaller diameter which in turn opens into digital cam cavity 70.
O-ring seal 47 is provided to hydraulically seal bore ~5 from bore 45a thereby preventing the ~low of hydraulic fluid into bore 45a. Piston 40 is provided with a pin like extension 48 projecting into bore 49. Piston 40 is permitted to axially translate within bore 45a so that pin 48 may project in~o the digital cam cavity 70 as will be described hereinafter.
The opposite end of piston 40, includes valve head 43 which is less in diameter than that of bore 45b thus permitting the unrestricted flow o~ hydraulic fluid thereby. Piston 40 is further provided extension cap 41 having notch 42 therein.
Piston 40 is normally biased to the left by action of spring 46 such that extension 41 is urged abuttingly against the end of bore 45b. Hydra~ulic fluid is thus permitted to enter inlet por-t Rl, ~xeely pass between piston 40 ancl eJastomeric valve seat 4~, past valve head 43, throu~h notch 42 and exit -throucJh outle-t port R2. Thus in the con~:icJuratiorl as shown in Figure 5 the 1uid pressure at outLet por-t R2 will be ec~ual to -the ~lu:id press~lrc at inlet port Rl.
During brake application the above describecl ~luid path throucJh proportioning valve 16 remains open until the fluid pressure delivered at inlet port Rl a-ttains a precletexmined level. ~t this time valve head 43 will close against valve seat 44. The level of pressure at which this occurs is depenclent ~ ~80~3~
upon -the force of spr:ing 46 as compared to the effective area of -the valve piston 40, acted upon by inlet fluid pressure in a direction opposing the force of spring 46~ This effective area is equal to the diameter D of piston 40 since the right hand end of piston 40 projec-ting into bore 45a is sealed oEf rom the inlet fluid pressure by O-ring seal 47 while the inlet fluid pressure acts against all of the remaining portions of piston 40.
After valve head ~13 closes against valve seat 44 and the fluid pressure at inlet port ~1 is further increased, the increased pressure will act against piston 40 over an effective circular area having a diameter equal to the main sealing diameter of valve head 43 less the cross-sectional area of piston 40 extending into bore 45a. This produces a force acting upon piston 40 in the same direction as an assisting spring 46 to reopen valve head 43 so as to deliver at least a portion of the increased fluid pressure to outlet port R2O However, any increased fluid pressure delivered to ou-tlet port R2 creates an opposing force upon piston 40. The opposing force tends to reclose valve head 43 against valve seat 44. The opposing forces tend to keep valve head 43 closely adjacent to valve seat ~4 thereby xestricting the flow of fluid from inlet por-t Rl to outle~ port R2 creatiny a pressure a-t the outlet port R2 which increases at a lower rate than the pressure at inl.et port Rl.
rrhe rat.io Oe the~ pressure.s is determined by the re:Lationship of the effcctlve area~s previoLIs:Ly reeerred -to and hellce the fluid pressure passincJ throuyh proportioning valve 16 rilay be propor tioned -to Eollow a precletermined relationship.
During tha-t portion of a brake application in which the app~ied pedal eEort is reduced subsequent to a brake application of su:~ficien-t intensity to have moved piston ~0 -to the restricted v ~ ~
flow positionthe forces tencling -to move piston ~0 -to the le~t are reduced and piston 40 translates to the righ-t under -the influence of the pressure at outlet port R2. As -the piston 40 moves right valve head ~3 is permitted to slide within the inner peripheral surface of valve seat 44, -thereby increasing the available volume for the fluid at the rear brake cylinders 15L
and 15R and accomplishin~ a reduction in pressure at outlet port R2. The pressure at outlet port R2 can never be greater than the pressure at inlet port Rl because valve seat 44 also acts as a fluid check valve permitting the flow of fluid from port R2 and into bore 45.
For a more detailed description relating -to propor-tioning valve operation and the clesign of particular propor~
tioning valve elements refer to U. S. Patent No. 3,423,936 issued to William Stelzer on January 28, 1969.
Figures ~ through 9 are to be referred to for the following description of the digital cam 25, its construction and operation. LSPV housing 19 is provided with a two step bore 60. FLoor 69 of bore 60 contains recessed therein semicircular slot 67 and journal recess 68. Cam driveshaft 50 is supported and re-tained as shown in Figure 4. Journal 51 of drivesllaE~ 50 is ro-tat:ionally recelved within journal recess 68. Sha~t 50 extencls generally normal -to bore floor 69 passincJ
through ancl rotationally supported by end cap 61. End cap 6:L
is ~n~lgly rctaLnecl within bore 60a ancl against shoulder 62 by action o~ snap rincJ 63. O-x;ing 55 is provided to seal the dig:ital cam chamber 70 erom the entrance of any contamlnation thereto. Cam driveshaft 50 protrudes externally of end cap 61 s~lEficiently -to permit rigicl engacJement thereo~ by linkage 30 (see Figure 3). Thus driveshaft 50 is caused to rota!e -through the same angular clisplacement as that of linkage 30~
~ ~8~3~
Digital carn 25 is rotationally supportecl on cam journal 52 of driveshaft 50 such that cam 25 may rotate relative to driveshaEt 50. Cam 25 is provided with a periph~ral recess 26 and axially ciirected knurls ~4 over a-t leas-t the working peripheral por-tion of cam 25. The working portion of cam 25 will become apparent as the function and operation are further described hereinafter. Pin 32 projects axially from cam 25 into and slidably engaging slo-t 67 in bore floor 69 -thereby lirniting the angular rotation of cam 25 to that are inscribed by slot 67. The inboard side 22 of cam 25 is milled providing inboard facing stepped surface 27. Circular recess 21 extends axially through cam 25 from the outboard surface 28 and slightly past the inboard facing stepped surface 27 thereby providing passageway 23 between outboard surface 28 and inboard surface 27. Mandrel 33 is axia]ly positioned within circular recess 21 extending outboard and slightly past outboard surface 28.
Torsion spring 34 is seated about mandrel 33,the helical portlon thereof being seated within circular recess 21 such that inboard leg 34a extends through passage way 23 in juxta-posed relation with inboard facing stepped surface 27 and enc~ages spring retention hole 29. Outboard spring leg 34b extends in juxtaposecl relation with outboard surface 2~ oE
aam 25 e~ten~ing irlto slot 54 of driveshaft 50 and engac3ing the flat cammlng surface 53. In thelr normal assembled sta-te as here:inabove described and shown in ~'igure 6, torsion spring legs 34a and 34b are spring loadecl so as to apply an angularly outward force upon sprinc~ retention hole 29 and the flat camming surEace 53 of clriveshaft 50. Slot 56 is provicled at the external and outboard end of car,~ driveshaft 50 to permit external adjustment~
~ 12 -. . ~
0 3 ~
In opera-tion cam 25 is caused to ro-tate with cam driveshaft 50 by reason of torsion spring 34 applyir.g spriny force upon cammincj surface 53 of shaft 50. However, should cam 25 be restricted from rotating because of interference between pin 32 and slot 67 or because of interference between cam 25 and pin 48 on valve pis-ton 40, cam driveshaft 50 may however, rotate relative to canl 25 by further compressing torsion spring 34. Thus, a spring drive mechanism is provided between cam driveshaft 50 and diyital cam 25 which allows :Eor over travel of shaft 50 when rotation of cam 25 is otherwise restricted.
Figures 3/ 5 through 7 and 10 depict the configuration of LSPV 20 under conditions of light vehicle loading. The vehicle frame 35 ls riding relatively high with respect to suspended axle 31. Thus linkage 30 positions digital cam 25 such that peripheral recess 26 permits pin 48 of piston 40 to axially translate in and out of digital cam chamber 70.
Proportioning valve 16 is permitted to freely function resulting in a master cylinder pressure to rear brake pressure rela-tionship as shown by the curve identified as "EMPTY" in rigure 2.
So long as the vehicle is lightly loaded proportioning valve 16 is function. Peripheral slot 26 accommodates operati.on of valve 16. IIowever, shoulcl valve piston pin ~8 protrude into cam chamher 70 a~l a result of vehicle braking aIld the vehicle encountered an e~treme roacl concli-tion cau.sing cam drives~af-t 50 to momentari.ly, over rotate ~rom excessi.ve compres~:ion o:~ the veh:icle suspension system, cam ~5 w.ill momentarily encJag~ valve piStOII pin ~ stopping khe camls counterclockw:Lse rok-lt.ion.
Iloweve.r, cam clriveshaft S0 is permiktecl to continu~ .its counter--c:Lockwise rotation by compression torsion spring 34. Such a condition :is illustratecl in Eigure 13.
1 ~3~
When the vehicle is loaded heavy the suspension system is compressed such that the vertical separation between frame 35 and axle 31 is reduced. Linkage 30 assu~es a configu~ation as depic-ted in Figure 11 thereby rotating digital cam 25 counterclockwise as shown. In this configuration the outermost periphery of cam 25 is rotated in a position that disables proportioning valve 16 by preventing the free translation piston 40. Thus in the loaded condition, as illustra-ted in Figure 11, the master eylinder pressure to rear brake pressure relationship is as shown by the curve identified as "LOADED" in Figure 2.
So long as the vehiele is in the loaded eondition the outer periphery of cam 25 will remain in the valve piston disabling configuration as illustrated in Figures ll and 12. In this configuration and when the applied braking load is such that valve piston 40 attempts to translate to the right valve piston pin 48 buts against cam 25 and engages the axial knurls 24 on the outer periphery of eam 25. Thus cam 25 is restricted from freely rotating. Any fur-ther rotation of cam driveshaft 50 resulting from road indueed vacillations of axle 31 wil.l be aeeofnmodated by eompression of tors.ion spring 34 as illustrated in Figure 12~
The angle A (Figure 6) between the pin 48 centerline and digital eam step 26a determines the vehicle load condition at whieh proporti.oning valve 16 is disabled therefore it is necessary that this ancJle be aeeurately fixed. Anc31e A i~
detexlni.ned for an unloaded vehicle ancl represents that angle throucJh wh.ich driveshaf-t 50 wi:ll rotate as the vehicle is loaded to that mid-loacl condition at which it is desi.red to ehange from -the "EMPTY" curve -to the "LOADED" curve as shown in Figure
2. Step 26b is located so as not to interfere with the operation of proportioning valve 16; pin 32 and slot 67 may also be configured so as to limit the clockwise rota-tion of cam 25 thereby preventing step 26b interfering with the operation of proportioning valve 16.
The LSPV as illustrated in Figures l through 13 accom~.odates counterclockwise rotation of cam driveshaft 50 upon compression of the vehicle suspension system. However, the LSPV may be easily adapted to accornmoda-te clockwise rota-tion as is illustrated in Figure l~. By relocation of slot 67 as shown in Figure 14 the mechanism is adapted for clockwise rotation.
While an embodiment of the invention has been described herein with considerable particularity, it will be understood tha-t the scope of the present invention is to be determined by the appended claims.
The LSPV as illustrated in Figures l through 13 accom~.odates counterclockwise rotation of cam driveshaft 50 upon compression of the vehicle suspension system. However, the LSPV may be easily adapted to accornmoda-te clockwise rota-tion as is illustrated in Figure l~. By relocation of slot 67 as shown in Figure 14 the mechanism is adapted for clockwise rotation.
While an embodiment of the invention has been described herein with considerable particularity, it will be understood tha-t the scope of the present invention is to be determined by the appended claims.
Claims (4)
1. A proportioning valve for a vehicle hydraulic brake system having a lock out mechanism whereby said valve may be selectively rendered inoperative for given vehicle load conditions comprising:
valve means including piston means responsive to hydraulic pressure for operating said valve means;
rotatable cam means having a cam profile communica-ting with said piston means, a rotatable shaft, coupling means between said cam means and said shaft whereby rotation of said shaft effects rotation of said cam means, said cam pro file being configured to impede movement of said piston means when said cam means is rotated to a given angular position thereby locking said valve means in an inoperative configura-tion, and means for rotating said rotatable shaft in response to vehicle load conditions.
valve means including piston means responsive to hydraulic pressure for operating said valve means;
rotatable cam means having a cam profile communica-ting with said piston means, a rotatable shaft, coupling means between said cam means and said shaft whereby rotation of said shaft effects rotation of said cam means, said cam pro file being configured to impede movement of said piston means when said cam means is rotated to a given angular position thereby locking said valve means in an inoperative configura-tion, and means for rotating said rotatable shaft in response to vehicle load conditions.
2. The proportioning valve as claimed in claim 1, wherein said rotatable cam means includes stop means whereby the angle of rotation of said cam means is limited to a pre-determined arc.
3. A proportioning valve for a vehicle hydraulic brake system having a valve locking mechanism whereby said valve may be rendered inoperative in an open bypass configura-tion under selected vehicle load conditions comprising:
a housing having a first bore and a second bore, the axes of said bores intersecting each other at a right angle, said first bore having therein proportioning valve means including piston means axially extending therethrough and extending into said second bore;
rotatable shaft means coaxial with and extending axially through said second bore, circular cam means coaxial with said second bore axis extending radially outward from said rotatable shaft means, coupling means between said ro-tatable shaft and said circular cam means whereby rotation of said shaft effects rotation of said circular cam means, said circular cam means including a cam profile communica-ting with said proportioning valve piston means, said cam profile configured to impede movement of said piston means when said cam means is rotated to a given angular position thereby constraining said valve in an open bypass configura-tion, and means for rotating said rotatable shaft in response to vehicle load conditions.
a housing having a first bore and a second bore, the axes of said bores intersecting each other at a right angle, said first bore having therein proportioning valve means including piston means axially extending therethrough and extending into said second bore;
rotatable shaft means coaxial with and extending axially through said second bore, circular cam means coaxial with said second bore axis extending radially outward from said rotatable shaft means, coupling means between said ro-tatable shaft and said circular cam means whereby rotation of said shaft effects rotation of said circular cam means, said circular cam means including a cam profile communica-ting with said proportioning valve piston means, said cam profile configured to impede movement of said piston means when said cam means is rotated to a given angular position thereby constraining said valve in an open bypass configura-tion, and means for rotating said rotatable shaft in response to vehicle load conditions.
4. The proportioning valve as claimed in claim 3, wherein said rotatable cam includes stop means whereby the angle of rotation of said cam is limited to a predeter-mined arc.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000437282A CA1176286A (en) | 1980-04-11 | 1983-09-21 | Vehicle hydraulic brake system and apparatus |
| CA000453869A CA1188351A (en) | 1980-04-11 | 1984-05-08 | Vehicle hydraulic brake system and apparatus |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13480180A | 1980-04-11 | 1980-04-11 | |
| US134,801 | 1980-04-11 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000437282A Division CA1176286A (en) | 1980-04-11 | 1983-09-21 | Vehicle hydraulic brake system and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180038A true CA1180038A (en) | 1984-12-27 |
Family
ID=22465077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000375136A Expired CA1180038A (en) | 1980-04-11 | 1981-04-09 | Vehicle hydraulic brake system and apparatus |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5718547A (en) |
| AR (1) | AR224192A1 (en) |
| BR (1) | BR8101987A (en) |
| CA (1) | CA1180038A (en) |
| DE (1) | DE3112925A1 (en) |
| ES (1) | ES8306978A1 (en) |
| FR (1) | FR2485457A1 (en) |
| GB (2) | GB2074273B (en) |
| IT (1) | IT1194780B (en) |
| MX (1) | MX152855A (en) |
| SE (1) | SE449834B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59136776A (en) * | 1983-01-25 | 1984-08-06 | 岩本 信行 | Manufacture of carving material for teaching aid |
| DE3828313A1 (en) * | 1988-08-20 | 1990-02-22 | Wabco Westinghouse Fahrzeug | Adjustment device for adjusting the braking force of a brake device |
| GB2402187B (en) * | 2003-05-31 | 2006-05-10 | Haldex Brake Products Ltd | Vehicle brake system |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3362758A (en) * | 1966-02-21 | 1968-01-09 | Bendix Corp | Brake proportioning means |
| GB1240590A (en) * | 1968-07-20 | 1971-07-28 | Aisin Seiki | Load responsive hydraulic brake pressure control mechanism of an automotive vehicle |
| US3503657A (en) * | 1969-01-27 | 1970-03-31 | Bendix Corp | Dualratio load sensing proportioning valve |
| US3649084A (en) * | 1969-10-13 | 1972-03-14 | Kelsey Hayes Co | Load controlled brake proportioning valve |
| US3734574A (en) * | 1971-03-02 | 1973-05-22 | Bendix Corp | Load sensing control device for a vehicle hydraulic braking system |
| US3768876A (en) * | 1971-06-11 | 1973-10-30 | Bendix Corp | Proportioning valve with load sensing blend back |
| US3848932A (en) * | 1973-07-02 | 1974-11-19 | Bendix Corp | Vehicle braking systems having height sensing proportioning valve |
| DE2550674A1 (en) * | 1975-11-12 | 1977-05-26 | Bosch Gmbh Robert | BRAKE PRESSURE REDUCER VALVE FOR MOTOR VEHICLES |
| DE2658353B2 (en) * | 1976-12-23 | 1980-02-07 | Wabco Fahrzeugbremsen Gmbh, 3000 Hannover | Load-dependent brake force regulator for a vehicle brake system that can be actuated by pressure medium |
| DE2719109C2 (en) * | 1977-04-29 | 1985-06-05 | Robert Bosch Gmbh, 7000 Stuttgart | Load-dependent brake pressure control device |
| US4150855A (en) * | 1977-10-28 | 1979-04-24 | General Motors Corporation | Vehicle load responsive brake actuating pressure proportioner and actuating linkage therefor |
| US4159855A (en) * | 1978-02-03 | 1979-07-03 | Wagner Electric Corporation | Load sensing proportioning valve |
| DE2812747A1 (en) * | 1978-03-23 | 1979-10-04 | Bosch Gmbh Robert | Safety interlock for load control brake valve - occupies medium setting if load input lever is broken |
| DE2823221A1 (en) * | 1978-05-27 | 1979-11-29 | Bosch Gmbh Robert | BRAKE FORCE CONTROLLER FOR VEHICLES |
| DE2856834A1 (en) * | 1978-12-30 | 1980-07-17 | Bosch Gmbh Robert | BRAKE FORCE REGULATOR |
-
1981
- 1981-03-31 DE DE19813112925 patent/DE3112925A1/en active Granted
- 1981-04-02 BR BR8101987A patent/BR8101987A/en not_active IP Right Cessation
- 1981-04-09 CA CA000375136A patent/CA1180038A/en not_active Expired
- 1981-04-09 IT IT21021/81A patent/IT1194780B/en active
- 1981-04-10 MX MX186798A patent/MX152855A/en unknown
- 1981-04-10 AR AR284936A patent/AR224192A1/en active
- 1981-04-10 ES ES501257A patent/ES8306978A1/en not_active Expired
- 1981-04-10 JP JP5308781A patent/JPS5718547A/en active Granted
- 1981-04-13 SE SE8102349A patent/SE449834B/en not_active IP Right Cessation
- 1981-04-13 GB GB8111537A patent/GB2074273B/en not_active Expired
- 1981-08-20 FR FR8116000A patent/FR2485457A1/en active Granted
-
1984
- 1984-02-08 GB GB08403330A patent/GB2140517B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3112925C2 (en) | 1992-09-24 |
| AR224192A1 (en) | 1981-10-30 |
| GB8403330D0 (en) | 1984-03-14 |
| SE8102349L (en) | 1981-10-12 |
| SE449834B (en) | 1987-05-25 |
| IT8121021A1 (en) | 1982-10-09 |
| JPS5718547A (en) | 1982-01-30 |
| ES501257A0 (en) | 1983-06-16 |
| BR8101987A (en) | 1981-10-13 |
| FR2485457A1 (en) | 1981-12-31 |
| IT1194780B (en) | 1988-09-28 |
| JPH026665B2 (en) | 1990-02-13 |
| MX152855A (en) | 1986-06-23 |
| ES8306978A1 (en) | 1983-06-16 |
| GB2140517B (en) | 1985-06-19 |
| GB2140517A (en) | 1984-11-28 |
| DE3112925A1 (en) | 1982-03-18 |
| GB2074273B (en) | 1985-01-03 |
| FR2485457B1 (en) | 1984-06-22 |
| IT8121021A0 (en) | 1981-04-09 |
| GB2074273A (en) | 1981-10-28 |
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Legal Events
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| MKEX | Expiry |