CA1067939A - Fluid brake control system - Google Patents

Abstract

ABSTRACT OF DISCLOSURE

A fluid brake control system is disclosed having an improved quick service and accelerated release control device having valves operable when rendered effective to locally reduce the brake pipe pressure to accelerate a brake application signal through a train and at other times to apply fluid to the brake pipe for accelerating the release of brakes of a train.
The control device comprises a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in pressure between respective brake pipe and reference fluid pressure chambers on opposite sides of the abutment. Two quick service valves of the ball poppet type are provided on one side of the abutment that are spring biased in the direction of the abutment against their valve seats to normally closed positions and have operating push rods longitudinally disposed between the associated ball poppet valves and one side of the abutment. A ball poppet valve on the other side of the abutment is also normally closed and is opened by movement of the abutment in the other direction for delivering fluid from an emergency reservoir to the brake pipe for providing accelerated release.

Description

~OG7g39 FLUID BRAKE CONTROL SYSTEM

1. Background of Invention This invention relates to fluid brake control systems, and while the invention is su~ject to a wide range of appli-cations, a preferred embodiment of the invention will be particularly described as applied to a fluid brake control system having an improved quick service and accelerated release control device.
The present invention is an improvement over currently used quick service and accelerated release control devices such 10. as the quick service and accelerated release control devices of the well-known ABD control valve generally used for governing the brakes of freight cars. In the ABD valve, a form of quick service function is provided by the service slide valve but to provide repeated quick service cycles as long as the brake pipe pressure continues to be reduced from an extraneous source, the ABD valve must be supplemented by a special q~ick service ontrol device such as the well-known Bl quick service valve.
` The accelerated release function as provided in the ABD valve requires separate control devices for service and 20. emergency release functions respectively. The AB~ device for ;
accelerated service release senses relative brake pipe and auxiliary reservoir pressures, while the accelerated release .
for an emergency brake application is provided by the actuation of a spool valve associated with an emergency release slide .
valve.
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These valves as provided in the ABD valve are costly to manufacture and are somewhat slow to respond because of sliding friction. Smooth and quick application and release of brakes~ of a train is dependent upon the speed at which a change 30~ in control is sensed by each car and passed along from car to 793~3 1. car, beginning at the front end of the train. It is therefore very important that there be as little delay as possible in the successive operation of the quick service and accelerated re-lease valves on the respective cars of a train. It is therefore highly desirable to increase the speed and integrity of pro-pagation of a brake control signal through a train over the rate of operation currently possible with ABD slide and spool valves.
An object of the present invention is to provide a 10. fluid brake control system having improved quick service and accelerated release valves which substantially obviate one or more of the limitations and disadvantages of the described prior system.
Another object of the present invention is to reduce the numbe~ of control devices required to provide the functions of quick service and accelerated release controls.
Another object of the present invention is to reduce manufacturing and maintenance cost of brake application and release control devices.
20. Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the descrip-tion of the invention progresses.
Summary of Invention A fluid brake control system is provided ~or a train of cars including a car having a brake control pipe, a quick action chamber s~ubject to charge periodically from the brake pipe and an improved quick service control device comprising a~housing containing a fluid pressure differential operated 30. abutment subject to actuation from a normal position by diff-~erences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment.

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1. Two poppet type valves are provided on the brake pipe pressure chamber side of th~ abutment for selectively venting the pressure chambers, each of the valves being spring biased in a direction of the abutment -to a normally closed position and the valves having respective operatiny push rods longitudinally disposed between the associcated val~es and the abutment. The poppet valves are opened by movement of the abutment in one direction from its normal position and fluid circuits are provid-ed, including the poppet valves, for permitting flow from the 10. brake pipe pressure chamber and from the reference pressure chamber respectively for cyclically locally reducing pressure in the brake pipe repeatedly as long as the brake pipe continues to be reduced in pressure independent of the action of the poppet valves~
-The above described control device also provides accelerated release control by providing a poppet type valve on the reference chamber side of the abutment that is spring biased~
in the direction of the abutment to a normally closed position, this valve having an operating push rod longitudinally disposed 20. between the poppe~ type valve and the abutment for opening the valve in accordance with movement of the abutment in the direc-tion of the reference pressure chamber to permit fluid to flow from the emergency reservoir to the brake pipe. Additional spring biasing means including a piston having an axial bore for free pa~sage of the vaLve operating push rod is provided for applying additional spring bias against movement of the - abutment in the direction of the reference pressure chamber to ~pen the accelerated release valve only when fluid pressure is materially reduced in the reference chamber~ such as after an 30. emergency brake application. Thus this spring is e~fective for a~cslerated release control after an emergency brake application but not after a service brake application.

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1. Although the functions of quick service and accelerated release are combined in a single control device as compared to prior use of several devices for each oE these functions, it is to be understood that the accelerated release control function and the quick service control function can be used separately, independent of the other function if such is the requirements of practice.
The poppet valves used are preferably of the ball type, spring biased to a closed position against a seat for 10. requiring a minimum travel of the abutment to actuate the valves with a minimum amount of friction involved. It has been found that satisfactory operation is obtained in an operating range of the abutment from its normal position of approximately fifty thousandths of an inch.
For a better understandiny of the present invention, ` together with other and further objects thereof, referance is had to the following description ta]cen in connection with the accompanying drawing, while its scope will be pointed out in the appending claims.
20. The drawing,is-a sectional axial view of a ~uick ser-vice and accelerated release control device together with a schematic diagram of a fluid brake control system in which it can be used as a preferred embodiment of the present invention.
With reference to FIG. 1, a fluid brake control system is illustrated for a typical car in a train including a brake control'pipe 10, a reference fluid reservoir in the form of quick action chamber ll that is subject to charge from the brake pipe 10 and an improved quick service control device 13.
~he device 13 has a housing 14 containing a fluid pressure diff-30. erential operated abutment 15 subject to actuation ~rom a normal position in which it is illustrated by differences in pre~sure between respective brake pipe and'reference fluid pressure ,' ~4-~6~9;~g 1. chambers 16 and 17 respectively acting on opposite sides of the abutment 15 within the housing 14.
Two poppet type valves 18 on the brake pipe pressure chamber side of the abutment 15 are provided for selectively venting the chambers 16 and 17, each of these valves 18 being biased by a spring 19 in the direcl:io.n of the abutment 15 to a normally closed position and the valves 18 having respective . operating push rods 20 longitudinally d.isposed between the associated valve 18 and the abutment 15. The poppet valves 18 10. are op~ned by movement of the abutment 15 downwardly and fluid circuits are controlled by the valves 18 for permitting fluid .. flow from the brake pipe pressure chamber and from the reference ~, pressure chamber respectively for cyclically locally reducing ,: . pressure in the brake pipe 10 as long as the brake pipe 10 continues to be reduced in pressure extraneous of the valves ` 18 as by brake pipe pressure reduction in an adjoining car or ., in the locomotive.
~ Improved accelerated release control is provided by , another poppet type valve 18 on the upper side of the abutment '~, 20. lS that is biased by a spring 19 in the direction of the abut--', ment 15 to a normally closed positionO This valve has an ., . operating push rod 20 longitudinally disposed between the associated poppet type valve 18 and the abutment lS for opening the accelerated release valve 18 ,in accordance with the movement ., ~
, ~ ~ upwardly of the abutment 15 from its normal position. When this q valve~is opened, fluid is supplied from emergency reservoir 12 : through the accelerated release valve 18 to the brake pipe 10.
Additiona} spring biasing means is used for accelerat-ed release after~an emerg.ency brake application, including a 30. piston 21 having an axial bore 33 for free passage of the push : ,', ., .
.',~` ~ rod 20 associated with the accelerated release valve 18~ The ~ ; pLston 21 is biased downwardly by a spring 22, and is biased , ~ 5 ~.. , .. ~ . .. .. .

~0~7~39 1. upwardly by fluid pressure in the reference chamber 17. It is this upward bias by fluid pressure ln chamber 17 that makes the spring 22 selectively effective against the abutment during accelerated release after an emergency application but not after a service brake application. The piston 21 is operable in a bore 23 to an extent limited by a stop 24 which is illustrated as a snap ring in the bore 23. This ring limits downward move-ment of the piston 21 so that it will have no influence on movement of the abutment 15 downwardly from its normal position 10. in which it is illustrated.
The laterally spaced push rods 20 associated with the valves 18 beneath the abutment 15 are connected at their upper ends by a bridge 25 that is pivotally connected to the right-hand push rod 20 by a pin 26. At a mid-point in the bridge 25, the bridge 25 is recessed downwardly at 25a to receive a detent 27 in abutment 15.
The abutment 15 comprises an annular diaphragm 28 secured between upper and lower housing portions 14a and 14b respectively, and annular diaphragm follower plates 29 and 30 20. are secuxed axially on upper and lower sides respectively of the diaphragm 28. The plate 29 has a bearing surface 29a for the lower end of push rod 22 above the abutment 15. Similarly the lower plate 30 has a detent 27 integral therewith for engagement with bridge 25 as has been described to operate the push rods 20 below the abutment 15 for actuation of the valves 18 below the abutment 15, and permit sequential operation of .
these valves 18, dependent upon relative forces of their springs 19. ~ .
A light stabilizing spring 31 is preferably disposed ~ 30. axially between plate 29 and the upper housing portion 14a as ~.
: provided by the two springs 19 of the valves 18 on the lower .
~ side of the abutment 150 Thus the val~es can be adjusted, if ~ ' .
~ ; ~6-1. desired, so that substantially the same dif~erence in pressure in one direction is required -to open the valves above the abut-ment 15 that is required in the opposite direction to open the valves below the abutment lS.
The valves 18 are similar in that they are ball poppet valves urged by springs 19 against ends of tubular resilient seats 32. The push rods 20 for ope:rating their associated valves 19 are operable with minimum friction within bores 33, and O-rings 34 are used to prevent leakage from the pressure 10. chambers 16 and 17. The push rods 20 are of reduced diameter at their ends adjoining the valves 18 to permit free passage of fluid through the associated valves 18 when these valves are opened. The valve biasing springs 19 are contained in suitable bores 35 in the housing 14. The lower right-hand push rod 20 is larger in diameter than the other push rods 20 to include an internal passage 36 as an inlet port for the lower right-hand valve 18. Also the push rod 20 for valve 18 on the upper side of the abutment 15 is longer than the other push rods to extend through a bore 33 in piston 21 as has been described, 20~ An accelerated release check valve 3~ is provided for connecting the accelerated release valve 18 to the brake pipe 10. The quick action chamher 11 is charged from the brake pipe 10 through a choke 38, and quick action chamber 11 is connected : to emergency reservoir 12 through a spill-over check valve 39.
In practice, the quick service and accelerated release control device 13 that has been d~scribed can be used in place : ~ of sev~ral valves providing coxresponding functions in the ABD
valve, thus simplifying and improving the ABD valve control apparatus~ It should be.considered that the simplified~dis~
30. alosure of a railway car braking system in the present em~odi-: ment is done to simplify the disclosure of the present invention :.
rather than to limit the environment in which the invention can , -::

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1. be applied. For example, additional controls can be provided as in the ABD valve for charging the emergency reservoir 12 and the quick action chamber 11 and in connection with venting the pressure chamber to atmosphere in accordance with the requirements of practice.
Upon initially charging the brake pipe 10, fluid enters chamber 16 via passage 40 and choke 41. The quick action chamber 11 also charges at this time through choke 38, and the emergency reservoir 12 can be charged from the brake pipe through a 10. suitable choke (not shown) as is done in the ABD valve. The reference chamber 17 is charged through port 42 from the quick action chamber 11. Thus, under normal conditions, chambers 16 and 17 are charged to substantially the same pressures, and the abutment 15 assumes its normal position as is illustrated permit-ting the closure of all valves 18 by their associated biasing springs 19.
- To illustrate the quick service operation of the control device 13, it will be assumed that the brake pipe 10 has been fully charged, and that a service brake application 20. is initiated by causing a continuous reduction in the pressure in brake pipe 10 at a service rate. This reduces the pressure in chamber 16 of oontrol device 13 relative to the reference pressure in chamber 17, causing the abutment 15 to be actuated downwardly to successively open the valves 18 below the abut-ment 15, the right-hand valve 18 being opened first because o having a weaker spring 19 than the left-hand valve so as to ; initlally vent fluid from the brake pipe through passage 40, choke 41,~ch~amber 16, passage 36, valve 18 and vent passage 44;
to atmosphere. Thus a cycle of local quick service reduction 30. of brake pipe pressure is initiated, and as the right-hand ~-:
valve 18 draws the pressure down further in chamber 1~ relative to chamher 17, tha abutment~lS becomes deflected downwardly .
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1. further so as to open the left-hand valve 18 for venting the quick action chamber 11 to atmosphere. The sequential opening of these valves is permitted by the rocking of the bridge 25 about its pivot point 25a on the detent 27 of ab~ltment 15.
Openin~ of the lower left-hand valve 18 causes quick action chamber air to be vented to vent passage 44 from the quick action chamber 11 through passage 45, inlet port 46, lower left-hand valve 18, outlet port 47, passage 48 and choke 49. When the lower left-hand valve 18 becomes fully opened, it ve~ts reference 10. chamber 17 at a faster rate than the venting of brake pipe chamber 16, and thus pressure difference between chambers 16 and 17 becomes reduced to a point of causing the abutment 15 to be restored substantially to its normal position, shutting off both lower valves 18 and completing a first cycle of operation for quick service reduction.
If the brake pipe 10 continues to be reduced in pressure from an extraneous source such as from the locomotive or from an adjoining car, brake pipe chamber 16 continues to reduce in pressure relative to the reference chamber 17, and 20. another cycle of operation like that which has just been des-cribed iq operable to again cyclically reduce the pressure in the brake pipe locally to provide more local quick service brake pipe reduction. These ~ycles of operation are e~fective continuously as long as there is a continuous extraneou~
reduction in pressure in brake pipe 10.
Typical choke sizes that have been found to provide . .
satisfactory cycling operation as described are .02, .125, .05 and .081 inches for chokes 38, 41, 43 and 49 respectively. It should be understood, however, that the sizes of these chokes 30. can be varied in accordance with the requirements of practice.
These sizes have been chosen to be used in connection with a well-known quick aation cbamber volume of 145 cubic inches that :: :
g_ ,, ~ , ,; . , " , ,, ,', , , . ~ ",, ,, .'. . " . . , . ' ! .. ! '. ` '. ' " ' ' ' ~0~7939 is built into a standard pipe bracket to which the control device 13 would be sec~red.
The frequency of cycling of the quick service valves is determined by the size of the choke 41 and varies inversely with the size of this choke. It has been found that sa-tisfactory operation is obtained with the size of choke 41 varying at least in a range from .097 to .125 inches.
Also the frequency of cycling of the quick service valves is dependent upon the relative volumes of the quick action chamber 11 and the brake pipe 10. The quick action volume is the same on all lengths of cars, while the brake pipe volume varies in accordance with the lengths of tlle cars.
It will be readily apparent from the mode of opera-tion as it has been described that where an entire train is equipped with this type of quick service control as a part of the control valve, the longer cars will have more air vented from their brake pipes than the smaller cars, thus reducing the necessity to provide auxiliary quick service valves for long cars as is the current practice. The present quick service valve that can be included as a part of an ABD type control valve, ~or example, therefore provides the dual function of increasing the rate of brake signal propagation for standard length cars and reducing the necessity of providing quick service valves separate from the ABD valve for longer cars.

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For consideration of the mode of operation to provide ~accelerated release, it will be assumed that the charging of the~brake pipe lO is initiated to cause release of a service application.~ Under these~conditions, the pressure in brake pipe~;~chamber 16 bullds;up more~rapidly than in reference 30. chamber~l7, causing abutment 15 to move upward]y and open the upper valve 18~to permit fluid from emergenc~ reservoir 12 to be~applied~ to the~ brake pipe 10. Under these conditions, 1. emergency reservoir 12 is connected -to brake pipe 10 through passage 50, input port 51 of accelerated release valve 18, output port 52, passage 53, choke 54 in the input to check valve 37, outlet port 55 of choke 37 and passage 56. It will be noted that in this mode of operation, the push rod 20 slides within the piston 21, as the piston 21 is maintained in its normal position as shown by fluid pressure in the reference chamber 17.
Thus the spring 22 does not ac-tuate piston 21 to a contacting position with the abutment 15 during accelerated release follow-10. ing a service brake application. As the pressure builds up inthe train brake pipe 10, the quick action chamber 11 becomes charged through its choke 38, and thus pressure builds up in chamber 17 of the control device 13 to terminate the local accelerated release by restoring the abutment 15 to its normal position.
To consider another condition of accelerated release, it will be assumed that brakes are to be released after an emergency application. During emergency braking conditions, the pressures in brake pipe chamber 16 and reference cha~ber 17 are 20. substantially depl~ted, and thus the piston 21 is actuated by its spring 22 to a position limited by the snap ring 24 in contact with the abutment 15 in its normal position. The pur- ~
pose of this additional spring applied to the abutment 15 is ~i to stabilize the abutment 15 to insure that it will not actuate the accelerated release valve to an open position in response to a small build-up of pressure in the train brake pipe 10 that is not intended as a signal for brake release.
When a brake release signal is applied to the train brake pipe 10 after an emergency application~ pressure builds 30. up in brake pipe chamber 16 faster than in reference chamber 17, and when the pressure difference is sufficient to overcome the additional biasing spring 22 as well as the pressure of the .

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1. stabilizing spring 31 and of the valve spring 19, the piston 21 and push rod 20 above abutment 15 are both actuated upwardly to open the accelerated rele.ise valve 18 and permit the application of fluid from the emergency reservoir 12 to the brake pipe for accelerated release as has been described when considering the mode of operation for release of a service brake application.
PLS was considered for a service brake release, the pressures in the brake pipe chamber 16 and the reference charnber 17 sub-stantially equalize, thus restoring the abutment 15 to its lO. normal position as is illustrated in FIG. 1 and restoring the accelerated release valve 18 and piston 21 to their normal positions.
I~aving thus described a fluid brake control system for a vehicle having an improved quick service and accelerated release control device as a preferred embodiment of the present invention, it is to be understood that various modifications and alterations may be made to the specific embodiment shown without department from the spirit or scope of the invention.

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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A fluid brake control system for a train of cars including a car having a brake control pipe, a reference fluid reservoir subject to charge periodically from the brake pipe, an emergency fluid reservoir, and an improved accelerated release control device comprising;
(a) a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment, (b) poppet type valve means on the reference chamber side of the abutment, the valve means being spring biased in the direction of the abutment to a normally closed position, and the valve means having an operating push rod longitudinally disposed between the poppet type valve means and the abutment for opening the valve means in accordance with movement of the abutment in one direction from its normal position, (c) fluid supply means responsive to the opening of the valve means for permitting fluid to flow from the emergency reservoir to the brake pipe, and (d) additional spring biasing means including a piston having an axial bore for free passage of the push rod for apply-ing additional spring bias against movement of the abutment in said one direction from its normal position only when fluid pressure is materially reduced in the reference chamber.

2. A fluid brake control system according to claim 1 wherein the piston is disposed in a bore in the housing, is spring biased in the direction of the abutment and biased in the opposite direction by fluid pressure in the reference chamber.

3. A fluid brake control system according to claim 2 wherein means is provided for mechanically limiting movement of the piston in the direction of the abutment to prevent the additional spring biasing means from causing movement of the abutment in an opposite direction from its normal position.

4. A fluid brake control system according to claim 3 wherein the mechanical means is a snap ring stop inserted in the bore in the housing between the piston and the abutment.

5. Fluid brake control apparatus for a railway car having a brake control pipe, a reference fluid reservoir which is at times charged from the brake pipe, an emergency fluid reservoir, and an accelerated release control device comprising:
(a) a housing having a fluid pressure differential operated abutment subject to actuation by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of said abutment, (b) valve means of the poppet type having relatively movable seat and closure elements at least one of which is operatively connected to said abutment, (c) fluid supply means responsive to the opening of said valve means by movement of said abutment in response to an increase in brake pipe pressure to permit fluid to flow from said emergency reservoir to the brake pipe, (d) and further means being rendered active in response to the attainment of a predetermined low pressure in said reference fluid reservoir which is indicative of an emergency brake application to apply an additional force to said abutment which resists opening of said valve means in response to an increase in brake pipe pressure of a magnitude less than a pre-determined amount.