CA1199666A - Relay valve assembly - Google Patents

Abstract

ABSTRACT:
A fluid system for the rail brake cylinder of a highway/
rail vehicle including a control valve responsive to brake pipe pressure drops to provide a control signal to a variable load relay valve assembly which provides brake cylinder pressures.
The relay valve assembly maintains the rail brakes deactivated in the highway mode, provides braking pressure independent of the variable load portion for low pressure in the control valve's auxiliary reservoir, maintains a rail reservoir and rail suspension supply changed from the highway and rail supply lines, and creates an emergency condition in the brake pipe for low rail supply line and or rail reservoir pressure.

Description

i66 sACKGROUND OF THE INVENTION
The present invention relates generally to air brake systems and more specifically for ar. air brake system and a relay valve to be used in a vehicle convertible between high-way and railroad modes of use.
S There has always been a great interest in the combined transportation of highway and rail vehicles. This has generally included the loading of road trailers onto flat bed rail cars which are then transported across the rails and then driven to location away from the rails. Efforts have also been made ! to equip trailers with road wheels and rail wheels such that the trailer itself forms both a road trailer and a rail car.
One such vehicle is described in ~. S. Patents 4 202,267 and ~,202,277 to Browne et al. The major problem with the prior art system including that of the above-mentioned pate~ts is that the designers have generally designed a brake system using highway technology and criteria which is unacceptable for use in a rail system.
As an example the s~stem in the aforementioned V. S.
Patents use a straight air brake system to operate the brake.
In this system the pressure and the brake pipe line are used to control a relay valve which in turn contrGls the brakes.
This style system had been used extensively in r~il vehicles but has been replaced by ~,BD ~air brake diaphragm) valves wherein the valve is responsive to modulation of the brake pipe pressure to produce its own brake con~rol signal. A
major advantage of the ~BD valves is that they provide better control and quicker response as well as the capability of providing braking control for a further distant or longer length train.

-2 366i Thus there exists a need for a braking system for a vehicle which is capable of highway and railway operation with a rail fluid braking system meeting the standards of the rail industry.

., i S~ RY 0~ THE INVENTIO~
An object of the present invention is to provide a fluid brak~ cGntrol system for a vehicle which may be used for highway as well as rail travel which incorporates the princi~le Il of modern rail technology.
Another object of the present invention is to provide a rail brake system for use on a vehicle which is capable of I highway as well as rail usage.
Still another ob~ect of the present invention is to provide a rail brake system for a vehicle whjch is capable of hiyhway ; as well as rail usage wherein the rail brakes are automatically deactivated during highway use.
Even another ob~ect of the present invention is to provide a rail braking system including a control valve and a relay valve wherein the relay valve is responsive to low pressure in ` the reservoirs of the control valve.
Still even a further object of the present invention is to provide a rail fluid bra~ing system including a control valve and relay valve wherein the relay valve provides an ' emergency brake signal on the brake line for low pressure in ~ th~ rail supply line or rail reservoir.
An even further o`vject of the present invention is to provide a brake control system for a vehicle which is capable of highway as well as rail travel wherein the suspension j system and the reservoir of the braking system for each car ,i are maintained charged by the rail supply line and the hiahwa~
supply li~e.
~hese and other objects of the invention are att2ined by providing a fluid brake control system includin~ a brake control pipe, a control valve responsive to the change of .

6~6 . I .

~' pressure in the brake control pipe to provide a control signal, a rail supply line and a highway supply line, and a xelay valve assembly responsive to the control signal from -the control valve and other sensed condition~ to provide the S appropriate brake cylinder pressures and signals. Th~ relay valve assembly is responsive to the presence of predetermined pressure in the highway supply line for maintaining the rail ,i brake cylinder deactivated by connecting the rail brake cylinder to an exhaust port. A load responsive, movable fulcrum lever ~ interconnects a first piston responsive to the control signal from the control valve and a self-lapping relay valve piston which connects a rail reservoir to the rail brake cylinder. A
plston in the relay valve assembly whose axis is colinear with ~ the relay valve axis is responsive to low pressure in the auxiliary reservoir of the control valve to actuate the relay valve independent of the variable load fulcrum. Check valves in the relay valve assembly interconnect the highway supply ~ line and the railroad supply line to a rail reservoir and the ; rail suspension system s~c~. that the rail suspension system and the rail reservoir are maintained fully charged irrespectlve of the mode o~ use of the venicle. Ihe relay valve assembly includes a piston valve responsive to low pressure in the rail supply line to interconnect the brake pipe to exhaust thereby ' creating an emergency pressure drop in the brake pipe so that the control valve will produce an emeraency bxaking signal to , the relay valve assembly.
Other objects, advanta~es and novel features of the present invention will b~come apparent fxom the follGwin~ detailed ,, description of the invention when considered in conjunction ,~ with the accompanying drawings.

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' BRIEF DESCRIPTION OF THE DR~INGS
!: .
Figure 1 is a block dlagram of the brake control system incorporating the principles of the present invention for use on a vehicle capable of highway and rail use.
Figure 2 is a cross-sectional representation of a relay valve assembly incorporating the principles of the presen~
~ invention.
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~l~99~ 6 i DESCRIPTION OF TH~ PREFERRED E.~lBODIMENTS
; As illustrated in Figure 1, each car includes at least a pair of rail wheels 10, a brake shoe 12, and a brake cylinder 14 as well as a suspension 16 illustrated as an air spring.
It shculd be noted that some vehicles which are capable of rail as well as highway use include one pair of wheels and appropriate brakes or may include two pairs of wheels and appropriate bra~es. For sa~e of illustration, Figure 1 shows a single wheel anà brake connected to the fluid brake con-trol system. Each car or trailer includes a brake pipe 18 and a rail supply line 20 both extending the length of the car with couplings at each end to a preceding and following car.
The fluid brake control system includes a control valve 22 having an emergency reservoir 24 and an auxiliary reservoir 26. Control valve 22 may be an ABD~ valve which is responsive to a change in pressure in the brake pipe to provide a proportional output from the auxiliary reservoir 26 as a con- I
trol signal CV. For an emexgency condition or pressure drop in the brake pipe, the control valve 22 provides an emergency control signal CV using both the auxiliary reservoir 26 and the emergency reservoir 24. The operation of the ABDW valve is well known and thus will not be described in detail.
The control signal CV from the control valve 22 is an input or pilot signal to the relay valve assembly 28. As will be evident from the description of the relay valve assembly in Figure 2, the control signal CV is a pilot signal and the volume of the relay valve assemblv in which i~ acts is relatively small. Thus the auxiliary reservoir ~6 and the emergency reservoir 24 may be substantially smaller than ~9~666 those used with a standard control valve 22. It should be noted that the volume of the relay valve assembly 28 which is responsive to the control signal CV is even so small that a volume 30 must be provided such that the combination of the volume 30 and the relay valve assembly 28 which receives a control valve signal in relationship to the auxiliary reservoir 26 and emergency reservoir 24 is proportional to the relationship of a brake cylinder and a full service aux,liary reservoir and e~ergency reservoir. It should be noted that the volume 30 ma~ be deleted if sufficient volume is provided in the relay valve assembly 28.
The relay valve assembly 28 includes arl input ~Crom rail supply line RSL 20 as weli as highway supply line ~,SL. These are used through the relay valve assembly to charge the rail reservoir 32 and the rail suspension supply 34. Air spring 16 is charged by the rail suspension supply 3q as is well known.
As will be explained more fully in relationship to Figure 2, the relay valve assembl~ 28 maintains the rail reservoir 32 and the rail suspension sup~ly 34 charged using either the ~ rail supply line RSL or the highway supply line ~SL. In normal operation, the relay valve assembly 28 cor.trols the pressure , BC to the brake cylindex 14 in response to the control signal CV using fluid from the rail reservoir 32. The relay valve assembly 28 is a variable load relay valve including a load sensor 36 connected to the air spring 16. This provides a load signal AS. The operation of the relay valve in response to control signal CV is varied using the load signal AS.
The relay valve assembly 28 is also responsi~e to the ~ presence of a predetermined fluid pressure in the highway supply line HSL to deactivate the brake cylinder 14 by connecting it ;` to the exhaust port EX. This prevents the brake 12 from being 66~i actuated when the vehicle is being used in the highway mode.
Pressure in the au~iliary reservoir 26 of the control valve 22 is monitored by the relay valve asse~bly 28. For a low pressure in the au~iliary reservoir 26, the relay valve assembly S 28 applies a large bra~e signal from the rail reservoir 32 to the brake cylinder 14. Thus if the au~iliary reservoir 26 has a low level, the reiay valve assembly will actuate the brake ; since the control valve is not capable of providing a control signal C~' to actuate the brake in response to an appropriate signal on the brake pipe 18.
For a ruptured, disconnected or otherwise inoperable rail-road supply line or rail reservoir, the relay valve assembly 28 connects the brake pipe 18 to e~haust so as to crea'e an emergency pressure drop in the brake pipe. The control valve 22 detects : the emergency pressure change and applies an emergency control sisnal CV to the relay valve assembly 28 ~hich in turn applies an emergency brake condition to the brake cylinder 1~.
The relay valve asse~bly is illustrated in detail in ; Figure 2 and includes a housing 90. The ~ailroad svpply line . ~SL is connected via passace 42 having restriction 44 and pacsage 46 to a check valve 48. The ou~put of the check valve ; is connected via passage 50, valve 52 and passage 5~ to the rail reservoir RR. The other side of the check valve ~ is also connected via passaae 50 and valve 56 to the rail suspension . supply RSS. The highway supply line HSL is connected via passage 58 to check valve 60 with the other side being connected tO passage 50. Thus, it can be seen that the rail suspension : supply RSS and the rail reservoir RR ~iay both be charged either by the rail supply line through check valve 4~ or : the highway supply line through check valve 60. It can also ~966~i;

'be seen that a lea~ downstream of check valve 98 that is larger than the flow or maintaining capabilities of restriction 44 will c~eate a pressure drop in passage 42. It can also be seen that a pressure drop in rail supply line can also cause a pressure drop in passage 42.
Passage 42 is connected to the top of diaphragm 62 of brake pipe vent valve 64. The pressure on the top of diaphragm 62 from passage 42 acts aaainst spring 66 on the bottom of the diaphraam. The space underneath the diaphragm is vent.ed to e~haust via port 68. Piston 72 is connected to the diaphragm 62 . and its movement controls check valve 72 which interconnects the brake pipe BP and the exhaust ~X. Spring 66 is selected such that wher the pressure in passage 42 drops below a predetermined pressure, for e~ample 80 p.s.i., the spring 66 forces the piston 70 against the check valve 72 to connect the bra~e pipe BP to exhaust EX. This creates an emergency rate of bra~e pipe pressure reduction that will be sensed by control valve 22, which will in turn react and propag~te the emergenc~- rate throughout the train. Each car will sense the emergenc~ brake rate reduction and so control the remainder of the re~ay valve assembly to brake each of the cars. Not only does this sive an inc.ication ` of a Eailure in the railroad supply line or rail resexvoir, but by providing an emergency brake sisnal to all the cars, the un~esirable applic~tion of vehicle-equi.pped spring brakes which . is held released with rail reservoir pressure, does not go und~tected.
The control signal CV from the control valve 22 is applied through passage 74 to the top of diaphragm 76 which ~;ill rest on piston 78. A spring 80 maintains the piston 78 in its utmost position. The piston 78 is pivotall~ connected at 82 to a lever i6~

84. The opposite end 86 of lever 84 is received in the base of . piston 88. A roller fulcru~ 90 determines the mechanical force relationship between the piston 78 and 88. The roller l, fulcrum 90 is rotatably mounted at one end of piston 92 I which is held to the far left position by spring ~4. The ; other end of piston 92 rests against diaphragm 96. The ; opposing side of the diaphragm is sensitive to the sensed load of the vehicle via air spring signal AS. For an air spring signal below the rating of the spring 94, the roller fulcrum is in the position illustrated in Figure 2 ~hich is considered an 18~ location compared to the 100~ location in phantom. Th~se percentages are the transfer or the relationship of the control signal CV to the output braking signal BC. -~
Thus for the lightest load, the brake cylinder pressure signal is 1~% of the control signal CV and for a full load, the brake . cyl~nder pressure is 100~ of the control signal CV.
Over piston 88 is diaphragm 98 and spool 100 and return spring 101 of self-lapping spool valve 102. The output channe~
. 104 from the relay spool valve 102 is connected to the interior . channel 106 of spool 100 to exhaust channel 108. Output channel 104 is also connected by passage 110 an~ restriction 112 to the top of diaphragm 98. Passage 114 connects the out.pu~ of passage 104 of the valve to the top of check valve 116 which interconnects the output passage 104 ana 2 fluid passage 118 . connected to the rail reservoir RR.
Connected between the output passage 104 of the relay spool valve 102 and the passage 120 connected to the brake cylinder BC is a brake cylinaer release valve 122. The piston 124 of the brake cylinder release valve 122 rests on the top surface of a diaphragm 126. The highway supply line HSL i~

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connected through passages 5~ and 128 to the other side of ài2phrasm 126. The piston 124 is hollow and includes a passage 130 which interconnects the output lC~ of the relay spcol valve 102 and ~he brake cylinder via passage 120 when in the position shown in Fisure 2. The pressure and output of passage 104 lS also communicative via passage 132 to the top of check valve 134 of the brake cylinder release valve 122 to cause it to be remained seated. Spring 136 maintained the check valve 134 seated and spring 138 maintains the plunger 124 in its down or lowered position.
~hen the vehicle is to be used in the highway mode, highway su~ply line HSL is activated and connected to passages 58 and 128 which provides a press~re on the bottom of diaphragm 126.
~or a preselected pressure, for exan,ple 25 p.s.i., plunger 124 is raised closing the passage 130 of the plunger again.st the check val~e. This cuts off the communication between the output 104 of the relay spool valve 102 and the brake cylinder passage 120. Upon the pressure rising above the predetermined ?ressure, the plunger continues its upward movement opening ~he check valve 1 4 thereby interconnecting the brake cylinder and the brake cylinder passage 120 to exhaust port 140. Thus, when the vehicle is connected for highway use as detected by brake cylinder release valve 122, the relay spool valve 102 is ~ aisconnected ~rom controlling the brake cylinder and the brake cyliJIder is connected to exhaust thereby deactivating the brake cylinder. This prevents the brake cylinder ~rom opera~ins while in the highway mode. This is important since if the brake cylinder was locked in the highway mode even though the rail wheels are no~ on the ground, sevexe damage may occur to the rail wheels if they should hit the ground and not be free to spin.

With the brake cylinder release valve 122 in the position illustrated in Figure 2, the output 104 of the self-lapping release spool valve 102 is effectively connected to the brake , cylinder passage 120. When the control valve 22 senses a brake pressure reduction, and responds by generating a control . signal CV to passa~e 74 of the relay valve assembly 28. This signal on diaphragm 76 drives piston 78 downward which affects . an upward ~otion of piston 88 through lever 84. The actual displacement of piston 88 is a function of displacemer.t of piston 78 and the position of the movable fulcrum 90 which vaxies with the sensed load. The piston 88 drives spool 100 . upward such that the .interior passage 106 i5 sealed closed against the check valve 116. This disconnects the brake cylinder passage 120 from the exhaust port 108.
~ Further remove~.er.t of piston 88 and spool 100 unseats the . check valve 116 and allows fluid under pressure from the . rail reservGir RR through passage 118 to be ported through passages 104, 130 and 120 to the brake cylinder on the vehicle.
The fluid press~re from rail reservoir passace 118 is also applied through passaye 110 to the top of diaphragm 98 which forces the piston 83 in the opposite direction or downward when the back pressure from the brake cylinder is greater than ! the force created by the control signal via pi~ton 78 and lever 84. Thus, the relay spool valve 102 matches a brake cylinder pressure with the pressure on piston 88 which ls a function of the control valve signal CV as varied by the sensed load.
The relay valve assembly 28 also includes an auxiliary reservoir protection device 141. The diaphragm 142 is connected by passage 14~ to the auxiliary reservoir and is mounted to a 9~66 plunger 146. Springs 148 and 150 force t~e plunger 146 upward ' and is maintained in its down position by the pressure of the auxlliary reservoir. When the pressure in the auxiliary , reservoir and passage 144 is less than a predetermined pressure, ' for example 32 p.s.i., the springs 1~8 and 150 cause the plunger 146 to rise coming into contact with plunge~ 88 to activate the relay spool valve 102. It should be noted that the axis of plunger 146 is co-linear with the axis of plunger , 88 and both of which are parallel to the axis of plunger 78 ~ o~ the control valve signais CV. This feature maintains the integrity of the re~ay valve assembly 28 to apply pressure to the brake cylinder from the rail reservoir RR regardless of the status of the au~iliary reservoir of the control valve 22.
This feature is necessary when the vehicle has been used extensively in the highway mode and then parked on a rail sicing with fully charged rail reservoirs but depleted au~iliary ; reservoir.
In the preceding description of the preferred embodiment, ~ it is evident that the objects of the invention are attained in that a fluid control brake system for a vehicle which is capable of highway and rail use is provided with many necessary features and compatibility with rail systems. Although th~
invention has been illustrated and described in detail, it is evident that this is by wa~ of illustration and example only , anc is not to be taken by ~ay of limitation. The relay valve assembly 28 as illustrated in Figure 2 is but an example of one layout of the required valves and elements and other layouts may be constructed. The essence of the present inven-tion is the use of specific valves performing specific functions ~ and the fluid communication of the di`~ferent elemer,ts and I

6~ 1 not necessarily the layout. Although the brake control system as illustrated in Figure 1 shows many distinct elements, the relay valve assembly 28 is an integrated unit and may be , mounted to the ~ace of a control valve 22 thereby eliminating extended interconnections. Although the relay valve assembly 28 was designed for the rail brake system of a vehicle having , rail and highway modes, certain features of the valve assembly are unique and distinct within themselves and may be used on any rail brake system. Thus, the spiri~ and scope of the present invention are to be limitec only by the terms of the appended claims.

Claims (4)

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

1. A variable load relay valve for use in a fluid brake control system having a first fluid supply, a second fluid supply, control valve means responsive to a brake command to provide a fluid control signal from said first fluid source and means for providing a sensed load signal comprising:
a control port for receiving a fluid control signal;
an exhaust port connected to the atmosphere;
a brake cylinder port for providing fluid to a brake cylinder;
a first fluid supply port for receiving fluid from a first fluid supply;
a second fluid supply port for receiving fluid from a second fluid supply;
a piston valve means for interconnecting said brake cylinder port with said exhaust port and said second fluid supply port to determine the degree of braking;
first piston means movable in response to a fluid control signal at said control port;
load means interconnecting said piston valve means and said first piston means for varying the effect that said fluid control signal on said firstpiston means produce on said piston valve means as a function of a sensed load signal; and second piston means movable in response to pressure on said first fluid supply port for controlling the operation of said piston valve independent of said load means to apply pressure from said second fluid supply port to said brake cylinder port when the pressure on said first fluid supply port is less than a predetermined value.

2. The variable load relay valve according to claim 1 wherein said load means includes a lever connected at one end to said first piston means and at its other end to said piston valve means and a movable fulcrum responsive to said sensed load signal.

3. The variable load relay valve according to claim 2 wherein the axis of said first piston means is parallel to the axis of said piston valve means, and the axis of said second piston means is co-linear with the axis of said piston valve means.

4. The variable load relay valve according to claim 2 wherein said fulcrumincludes a third piston means movable in response to a fluid load signal.