CA1183185A - Valve structure - Google Patents

Abstract

Abstract of the Disclosure A normally closed valve for normally conducting fluid under pressure from a first source to a point of lower pressure for performing a first function and having a control port connected to a second source of fluid under pressure normally performing a second function. The valve is provided with an actuator for holding the valve open and which actuator causes the valve to close when the second function.
The valve is particularly suitable for use in a conventional air brake system for vehicle wherein separate sources of air under pressure are employed to conduct air to a service brake air chamber for applying the brakes during normal running conditions and to a spring brake air chamber for holding the spring actuated braking device out of braking condition except when used for parking or in an emergency.
In this application the valve permits the application of both the service brake force and spring brake force to enhance the holding effect. The valve includes a limiting check valve action wherein the pressure developed in the service brake line is relieved when it exceeds a predetermined amount.

Description

33~

~0 This inventlon relates to a rlovel valve which in ~oDIe re~pec ts operates in a manner oppo~i te to the operation o:E a converltional pik~t operated check V~ veo The! v~lve is con~tructed ~o a~ to permit normal flo~ OI fluiù uncler pres~ure to a point OI lov~er presæur~ Ior per:Eor~ning a :first ~eunctior~ and ~s also connected to a ~;econsi source o~ fluid under pre~Ure ~or ~ormally permitting the per~OrrQanCe O:L~ a ~ecorld ~unction. The ob,je~t o~ the valve i~ to prevent per:formance OI both function$ when it i~ destred to preverlt perIorolance o~
the second lunction.
2û A:lthough the valve has numerou~ applic~t~on~ it will be de~cr1bed i~ ~onnection with its a~plicabi:l ity to a conventional alr brake sy~tem :~>r vehicle3 ~herein the valve ca~ connect the two ~ource~ of ~ir under pressure ~hich are employed to perfor~ the service bra~e ~unction and also the sprlng brake function wherein a~r is employed to pre~ent the applicatio~ b~ ~pri~g mean~ o~ a holding force which is normally u~ed in parking or in emergencies.
The maln obje~ o~ the present invention is the proviæion of a valve structur,e adapted to prevent the per~ormance of two functions when it i~ desîred to prevent the per~orm2nce o~ one function.
Another ob~,ect of the invention is the provision o~ a ~LL~3~ ~5 1 valve structure which l~mits the pre~ure wh:lch may be huilt up with respect to one of the ~unctions per~or~ed and more speciflcally, in an air brake ~y~tem, to limit the service brake pressure ~ prevent it from exceeding ~ predetermined desi~n amount which ~lght otherwi~e c:au~e ~ilure.
Oth~r ob~ect~ and advant~ge~ wlll be ~pparent ~rom the ~ollowing speci~ication and ~rawin~.
Flg. 1 is a schematic showillg one appl-lcation o~ the valve a~ applied to a conventional ~I.r brake ~stem.
lo Fig. 2 iæ a longi~ucllnal ~ection through the valve.
In detall, and ~irst with re~erence to Fig. 1, t~o tank~ o:~ air ~nder pressure are i.~dicated. The servlce brake air ~ouree being indicat~d at 10 and the spring brake source at 12. In the line 14 ~rom the servic0 brake source is a pedal astuated valve 16 which ~hen opened conducts air through condult 14 to a quick release valve 1~ and thence throu~h line~ 20 to service bra~e chambers 22.
Line 26 ~rom the ~pring bra~e source conducts air to another quick relea~e valve 18 from which air ls oonduct~d ~0 through lines 28 to spring br~ke air chambers 30O Line 14 also ~eds li~e 32 which runduct~ Rir to the servlce bra~e chambers 34 of the ~ront a~le which does ~ot in~ ude spri~g brake chamber~
The above described structure is conventional and i~
almo~t e~clu~ively employed in present air brake systems. The sprillg brake chamberæ 30 are e~ploged to oppose a spring (not shown) which, at all times, urges the brake~ to brake apply-lng condition~ This spri~g means i~ normalXy.oppos~d ~y the ~ressure in chambers 30 and such pressure is not released until ~0 a valve 36 in line 2~ i~ actuate~ by the operator. The air ch~mber~ 22 are supplied ~ith air under pre~sure under ~ormal runn~ng eonditions ~hen the pedal actuated valve 16 i~ opened ~3~
1 by th~ operator.
By the present i~vention the two above de~cribed sy~tems are conne~ted by a novel valve 40, detai1s o~ which are sho~n ln Fig. 2. Thi~ valve 40 is c~nn~cted at one end by line 4~ with ~he normal e~haust port 48 o~ the quick relense valve 18 connected to the service braXe chamber~ 22.
At its opposlte end valve 40 l~ provldecl with a port ~4 which ig collnected by mea~s o~' a line ~6 w:lth one o~ the lines 28 whlch supply the ai.r ~hambers 30.
At this point lt should be noted that the ri~h~ hand quick release valve 18 ~ermlt~ exhaustlng o~ th~ chambers 22 throu~h e~haust port 48 when the ped~l operated valve 16 is released by the operator. The ~tru~ture $hat per~its release o~ the brakes by ~ulck release valves 18 ~ ~ell known.
Re~erring no~ to Fig. 2 lt wlll be seen that said line 42 co~ducts the axhaust ~ro~ the adjacent quick release valve 18 through a central opening 52 in a ~leeve 54 which in turn is slidably mounted in a central bore 56 ~or~ed centrally of the body o~ valve 40. Such exh~ust is conducted through bore 52 20 p~st a normally open ball 58 ~hich 1s adapted to cooperate with a valve seat 69 formed in said sleeve 54. The e~haust is then conducted past Bellev1lle springs 62 and out an e~hau~t opening At -thi~ point it will be seen that the nor~ally open valve element 58 permits the quick release valve 18 i~ lines 20 to operate in a ~lormal ~ er e~cept that lnstead o~ being exhausted diPectly to the atmosphere the air ~rom chambers 22 i~ e~hausted through valve 40.
The ball 58 is urged at all time~ to~ard seat 6~ by 30 comp~es~ion spring 68 which is interpo~ed between said ball 58 and a centra11y apertured hea~ plate 70 ~hlch is ~ecured to sleeve 54 by scre~s 72. The ball 58 is normally he1d o~ the ~3~

~ea~ 60 to permi t the above mentione~ e~haus l; operation b~
means o:l~ a pu~h rod 74 which i~ slidably mourltecl within a eap 76 and which push rod is ~ormed ~rith an enlaxged head 78 at its le:iEt hand end. A compression spring ~0 urge~ the push rod 7~ to the leiet as seen ln Fig. 2, but the Iorce o:~ ~aid spring 80 is normally overcome by a pres~ure respon~ive diaphragm 82 secured to the le:e t hand end OI eap 76 by mearl~ o:l~ head 84 and bolts 86. The ~pace to the ri~h~ o:~ diaphr~gm ~2 :Is vented by port 77.
à l['he port ~a4 is ~ormed in 1~ ad 84 arld i~ ~onnected to line 46 which in turn ~ connected, as be~t seen ~ n Fig . 1, to line~ 28 which are normally under the pressure whlch is appli~sd to chamber~ 3 0 .
From Fig. 2 it ~vl 11 be apparent that as long as air prl3ssure ls applied to chambers 30 and diaphPagm 82 the pu3h rod 74 hol~s the ball 58 oï~ the ~eat 60 and îhus permits the nor~al exhausting s: I service brake chambers 22 . However, wher valve 36 (Ftg. 1) i6 opened by the operator 1;he llne~ 28 are, of cour~3e~ ezhall~ted to atmo~phere so that spring 80 pushe$ the 20 diaphragm 82 to at least lthe dotted line position of Fig . 2 thus permi tting the pu~h rod 74 to moY0 to~.-the le:~t a~d permitîing ball 58 to seat under the urgency of spriDg 68.
Whe~ ball 5B closes the valve, two ~unct io~ are per~ormed:
f ir~t, alr p:res~ure i~ released from charnbers 30 pernaitt:Lng the spring therein to apply the bral~es ~ith the ~orce of said sprt~gs; seconlcl, the! lines 20 are not permitted to exhaust becau~e OI the clo~ing oR valve element ~8 and whatever pressure is appl ied to service brake ch~mbers 22 by valve 16 r emains on the brakes. In thi~ anner the ~braking ~orce~ attributable 30 to the service brakes and ~ the spring brake~ are combined to provide a much hlgher braking :Eoroe than iæ normally provided by ei ther ~

3~

When the valve o~ the pre~ent lnv~ntion ls employed -to combine the eI:~ectl vene~s of the two air brake sy~tem~ an important fea ture m~y be lncorpora1;ed in the structllre o:~ va1ve 40, The 61eeve 54 i s norma1ly urged ts:~ the position of Fig . 2 by at ,1east one pair o-f Belleville ~prings ~2 which urge the sleeve 54 agairls-t a stop 90 whlc11 may tal:e the :~orm o~ a snap ring r~sceived ln an appropriately formed groove i.n bnre 56.
In addition ~ an annu1ar diaphragm 92 i~ cured a t l t~ ou ter periphery by mearl~ OI a rlng ~4 and bol t~3 96 to the right handl 15) end o~ the valve body and is secured at its inner perlphery between plate 70 and sleeve 54. By this ~tructure T~lovement o:~
s1eeve 54 to the le:ft against the urgency o~ Bel1evl11e springs ~;2 ~vill occur when the pressure ln 1ine 42 ~xceeds a predeter-mined amount set by the ~orce of sald Belleville springs. ~pon ~ovement o-~ the ~leeve 54 to the le~t, with the push rod 74 now stopped by the diaphrag~ 82 and the end ~all, the ball 58 i~ lift~d o~f seat 60 per~ltting e~haust through e~hau~t port 64, thus lowering the pre~sure in the service brake chambers 22 to a predetermlned pres~ure correspondlng to the design pressure of the service brake ~y~tem. Belleville springs 62 may be apertured to enhance ~ree ~low to exhau~t port 6~
In the par-ticular application above described with re~pect to air brakes it is important to note that th~re is no direct eonnection bet~een the air in the spring brake ~y~te~
and in the air in the service brake system -- the diaphr~gm 82 separating the two systems at all times. In add~tion to the ge~ral de~irabilitg o~ this ~eature i$ wlll be noted that the presence o~ valYe 40 ha~ no e~ect on the normal operation o~
the æervice brake s~ystem.
It ~1~1 be understood that ~hould valve 40 be employed in a hydraulie syst~sm havin~ a liquid ~edium eer~in ~llght modi~ications, ~uch a$ ~he addltion of various seal~:, may 3~
be r0qulr~d.
In Fig. 1 only ~he brake~ or o~e a~le are shown.
The s am~ arr angem~nt may be e~np loy~d :~or add i t i ona 1 axl es as lndieat~d by the arro~ and :for ltrailer axle~ a traller :i 9 invvlved .
Another Ieature OI the above de~cribed arrangQment is that when a plurality of axl0æ a~dl th~?ir brake system~3 are i~volved the failure o:~ a brake sy~tem O:L one a~le h~q~ no e:~Iect on the operation OI the rema.Lnlng a~le~ alld their bra~e~.
'10

Claims (8)

I CLAIM:

1. In a vehicle air brake system that includes a first brake applying air chamber and an air service brake conduit connected to said first chamber for applying such brake when air pressure is applied through said conduit during normal running operation of the vehicle, the system further including second brake applying air chamber and a spring brake conduit adapted to exhaust said second chamber for applying such brake by spring means cooperating with said second chamber when vehicle is parked or during emergency braking the improvement that comprises:
an air brake holding valve body interposed between said service brake conduit and said spring brake conduit, said valve body including an air service port connected to said air service conduit, and a spring brake supply line port connected to said spring brake conduit, a valve element in said body adapted to be opened to allow exhausting of said first chamber through said air service brake conduit when pressure is released in said first air chamber during normal running of the vehicle, means in said valve body holding said valve element open by the pressure in said spring brake conduit and allowing said element to close when said chamber is exhausted to activate said spring means, whereby said first and second brake applying air chambers are both activated when said spring brake is activated and said service brake pressure is applied.

2. A valve body according to claim 1 wherein said valve body includes an exhaust port mormally connected with said air service brake conduit through said open valve element.

3. A valve body according to claim 1 wherein a push rod is provided in said body normally urging said valve element to open position, spring means urging said push rod away from valve opening position and means responsive to pressure in said spring brake conduit for normally overcoming the force of said spring means to hold said valve element in open position.

4. A valve body according to claim 1 wherein a valve seat cooperates with said valve element to permit closing said valve, means responsive to an elevated pressure in said service brake conduit for moving said seat away from valve closing position to permlt opening of said valve.

5. A valve body according to claim 4 wherein said seat is formed within a sleeve adapted to be moved toward valve opening position by such elevated pressure.

6. A valve body according to claim 5 wherein a deformable diaphragm is connected to said sleeve and adapted to receive the pressure in said service brake conduit on one side thereof.

7. In a fluid driven system having a first conduit normally under fluid pressure for performing a first function and a second conduit adapted to be exhausted to atmosphere for performing a second function, a vavle connected to said first and second conduits, said valve including a normally closed valve element adapted to be opened to connect said second conduit with atmosphere, means in said valve holding said element open by pressure in said first conduit, whereby said valve is closed to prevent performance of said second function when said pressure is reduced to prevent performance of said first function.

8. A valve according to claim 7 wherein means is provided for opening said valve to atmosphere by pressure in said second conduit.