US3004800A

US3004800A - Wheel spin inhibiting apparatus

Info

Publication number: US3004800A
Application number: US64640A
Authority: US
Inventors: John R Edmund
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1960-10-24
Filing date: 1960-10-24
Publication date: 1961-10-17
Anticipated expiration: 1978-10-17

Description

Oct. 17, 1961 J. R. EDMUND 3,004,800

WHEEL SPIN INHIBITING APPARATUS Filed 001;. 24, 1960 DIRECTION OF FREE FLOW INVENTOR. JOHN R. EDMUND 4 A WUAWE United States Patent 3,004,800 WHEEL SPIN. INHIBITING APPARATUS John R. Edmund, Berkeley, Calif., assignor to Westing house Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Filed Oct. 24, 1960, Ser; No. 64,640 7 Claims. (Cl. 303-21) This invention relates to wheel-spin inhibiting'apparatus for use with railway locomotives and, more particularly, to control apparatus, including means responsive to spinning or slipping of a locomotive driverwheel or wheels caused by excessive propulsion power applied thereto, for terminating such spinning or slipping. As used hereinafter, the terms spinning or slippi'r1g will apply to that condition in which the angular rate of speed of a wheel, at any given instant, exceeds that corresponding to the linear rate of speed of the vehicle.

As is well known, spinning of locomotive driver wheels often occurs during the initial efior'ts of getting a train under way, due perhaps to excessive weight carried by.

a train of cars or to unfavorable grade or track conditions, or a combination thereof, in which case the propulsion effort applied to the locomotivewhe'els exceeds the. resistant force offered by the adhesion orf rictio'n between the wheels and the rails. Customarily, the op: erator cuts off the propulsion power and efiects sanding of the rails to terminate-a spinning condition of the locomotive wheels, but thisv method is so time consuming that offtimes any momentum gained by the train is lost 2 a transfer valve operated by two opposingly arranged pistons, one having a smaller pressure area than the other and operative when subjected to reduced main res} ervoir' pressure to move the transfer valve toit's change.- over position in which communication is established via which reduced main reservoir pressure is supplied to the l brake cylinder and also to act on the larger piston.

during the time interval necessary for correcting the wheel-spinning. It has been found more effective to maintain the propulsion efiort on the wheels while wheel spin correction is. being effected, thus enabling the train to maintain maximum inertia of movement under the circumstances. In order to maintain a high degree of efii ciency,"that is, keep the train moving with a minimum lossiof. inertia during wheel-spin correction, the wheel! spin condition should be corrected in as short a period of, time-as is possible and with the least amount of re tarding effect on the vehicle Wheel as is necessary to tier minate wheel spin and restoremaximum tractive friction.

Accordingly, the object of this invention is to provide an apparatus' for inhibiting or correctingwheel-spin of a locomotive driver wheel or .wheels during propulsion thereof,'said apparatus being capable of causing said wheel or'wheels to regain maximum tractive friction, during the period of wheel-spin correction, without cutting off theipropulsive effort acting thereon and without appreciabile loss of inertial of motion 'already developed by the train;

1 Briefly, the, apparatus embodying the invention comprises a transfer valve device operably controlled by any suitable wheel-spin sensing device, responsively to a con trol impulse elfected by the wheel-spin sensing device uponoccurrence ofa spinning condition of the wheels to cause a trans-fer valve inthe valve device to be'cyclically operated between a normal position, in which'a first communication is establishedjbetween. the brake cylinder andthe brake cylinder pipe to permit normal operation of the, brakes under normal conditions, and a change-over position in which said first communication isdisestablished and a second communication between the brake cylinder and the main reservoir is established. The cycling action of the transfer valve device effects a seriesof nuid pressure impulses from the main reservoir, at a reduced degree by the use ofa pressure limiting valve, to thebrake cylinder to cause a series of momentary retarding impulses to be applied to the spinning wheels until thecontrol impulse elfected by the wheel spin sensing device is-terminated by termination of" the spinning condition. The transfer'valvedevice comprises When the pressure acting on the larger piston builds up sutficiently, the transfer valve is biased back to its nor! mal position in which it remains until the pressure acting on the larger piston is gradually reduced to a value at which the pressure acting on the smaller pistonis again effective to shift the transfer valve to its changeoverposition. A choke device and timing volume are- As represented by the drawing, the wheel-spin inhibiting apparatus embodying the invention may comprise abrake cylinder device 1 partly cut away to expose a piston 2 and a pressure chamber 3-therein, said brake cylin der device being employed in the usual manner for operating brake shoes (not shown) associated with. vehicle driver wheels (not shown) through any suitable standard type brake rigging fou nd on a railway locomotive. The apparatus further comprises a source of fiuid'under pressure in the form of a main reservior 4 associated with the normal brake system of the locomotive, a transfer valve device 5 for controlling supply of fluid under pressure from reservoir 4 to the brake cylinder device 1 and release of such pressure therefrom, .a pressure limiting device 6 interposed between saidmain reservoir and said transfer valve device for reducing the pressure of fluid suplied to said brake cylinder from said reservoir', a timing volume 7 of predetermined, volumetric capacity associated with said transfer valve device, a choke and check valve device 8 interposed between said trans fer valve device and said timing volume, an electrical energizing circuit, indicated generally by the reference numeral 9, for energizing a solenoid valve device 10 esf sociated with said transfer valve device, a wheel-spin sensing apparatus indicated generally by the referencev numeral 11.

As shown, the apparatus 11 may be of the type' sociated with a pair of electric motors 12 and.13.for driving respective axles (not shown) on each of which is mounted, at opposite ends, a pair of driver wheels (not shown) for rotation therewith, and an electro-responsive relay 14 controlled by' said wheel-spin sensing apparatus for opening and closing said energizing cir cuit. A generator '15, driven in the usual manner as by a diesel engine (not shown), for example, provides the electrical current for driving the motors 1 2 and 13.

Each associated pair of wheel-and-axle units, such as those drivenby

motors

12 and 13 respectively, (and it will be understood that there maybe any suitable, number of such pairs on a locomotive) is provided with a' brake cylinder, shown as brake cylinder 1, for applying and releasing the brake shoes associated with the wheels of the corresponding associated pair of axles.

The wheel-spin sensing apparatus 11 shown is similar to the sensing circuit shown and described in greater detail in the locomotiveengineers Operating Manual,

Patented Oct. 17, 1961 apparatus 11 and its function will be described herein only to an extent deemed necessary for an understanding of the invention. Apparatus l l includes in. a sensing ci=rcuit, in addition to the generator 15 and the

motors

12 and 13,

respective field coils

16 and 17 for said motors, a take-off lead wire 18' from'the generator to the field coils',and a return wire 19 from the motors to the generator. The motorsll' and 13, with their respective series-connected

field coils

16 and 17, are connected in parallel relation to each other by

wires

20 and 21, respeot'ively. The relay 14 includes a coil 22 connected across the wires 20' and 21 by a wire 23-, said coil when energized and deenergized acting to close and open, respectively, a switch arm 2'4 for closing and opening the energizing circuit 9," the latter circuit being provided with'a source of directjcurrent power, such as a battery 25, for energizing the solenoid valve devicelflassociated with the transfer valve device 5.

r The solenoid'valve device I10, which pilots operation of the transfer valve device 5, comprises a solenoid 26 connected to the energizing circuit 9 and a valve member" 27 which is biased by a spring 28 toward a normal or seated position on a valve seat 29'for cutting ofl communication between a passageway 30, connected by a conduit 31 to the main reservoir 4, and a passageway 32 leading to a pressure chamber 33 formed in the transfer valve device 5. Bnergization of the solenoid 2o actuates the plunger type stern of valve mem er 27 to move the valve'rhember to a' supply or unse at ed position off valve seat 29' for 'establishirig communication between passageways 30' and 32Tand, therefore, between rnain reservoir 4 charriber33"via conduit 31. An atmosphericpas sageway 34' formed in the stem of valve member 27 perventing of chamber via passageway 32 when said valve member is "in its seated position. i t

"The transfenvalve device 5, withwhich the solenoid valve device 10 is" associated, comprises a casing 35 in which is'disposed'a piston valve 'assemblagehaving a pilot piston 36 fixed to; one end of a spool valve 37 adjacent chamber 33, said pilot pistonhaving one side or pressure as. thereof l is ss is Pr u .5 flui p evaili in sa sn 's va c r s ca 3. h v aa nlcssure ra of at e fe ive are th n h Pr sure a e of F P s i m (a ly e med a y a r wdh cadedconnec'tion, to the opposite end of spool valve 37,. its 5fiffi being ifis'fi d t xfl is P e s e Prevailing eontr'ol chamber 3 in opposing relation to fluid p e W 9 "h P t P slqn- A pri g urges the piston-valve assemblage tqward a normal position in WW i .Pl QIi P 9f 89. v lve 37 connects. an annular cavity 42 and an axially spaced annularcavity formed in casing 35 for placing a conduit 44, conns cavity w th ham-ba f h ra yl n #35 9m isti m w th a o u 4 conn in the usual manner to a distributing. or control valve. (not 'shewn) operably controlled by an engineers brake ii- W wh by 51. 1 11 and release of fluid under pressure to and from, respectively, the brake cylinder device "may be controlled; iu ihfi usual. manner, for normal braking operation. I i

fil masseuse is c ra le out ofits normal positiomin response to. fluid pressure. acting on the pressure face of pilot. piston 36 andprevailing .over: the combined opposing forcesv of spring, 40 and of fluid pressure acting on the pressure face of control piston 38, to a ehange-over position in which the undercut portion 41 moves out of registry with cavity 43, to. cut oti commun-ication between

conduits

45 and 44. In the changeover position of the piston valve assemblage, the undercut portion 41 is in registry with an annular. cavity. 46

formed in" casing 35 while. remaining in registry. with ealv ity 42 for placing conduit 44 incommunication with a conduit 47. connecting said cavity46, with main reserroir, and thereby effecting supply of fluid, pressure from said reservoir to pressure chamber 3 of the brake cylinder device 1. A conduit 48, in which the choke and check valve device 8 is inter-posed, connects control chamber 39 of the transfer valve device 5 with conduit 44 while timing volume 7 is also connected to said control chamher and said conduit 48, on the control chamber side of said choke and check valve device, through a branch conduit 49.

The choke and check valve device 8 is characterized by structure that restricts the rate of flow of fluid under pressure therethrough in one direction only while permitting free flow in the opposite direction indicated by the arrow in the drawing. The choke device 8, as'shown in the drawing, comprises. a casing 50 having formed therein a circular opening 51 partly into which a cup-like check valve member 52, slidably operable in a guide bore 53 formed in said casing, is urged by a spring 54 until said check valve member rests in a normal position against one end of an adjusting screw 55. The adjusting screw 55 is pre-set so as to leave a precisely predetermined amount of clearance between the check valve member 5-2 and the circular opening 51 to permit restricted flow-in a reverse direction to that indicated by the arrow at a rate determined by said clearance, the other end of said adjusting screw being accessible from the exterior of the casing for making the desired setting. The compression value of spring 54 is such as to permit the check valve member 52 to be readily displaced from the opening 51 by pressure of fluid flowing in the one direction indicated by the arrow, whereby flow in said one direction is unrestricted.

In normal operation, that is, during such time that no wheel-spinning occurs, operation of the locomotive brakes is controlled in the usual manner by the engineers brake valve (not shown), whereby supply of fluid under pressure fr m an auxiliary reservoir (not shown) through a distributing or control valve (not shown), for example, through conduit 45, valve device 5 (with valve 37 in its normal position) and conduit 44 (to the brake cylinder device 1 may be effected for effecting a brake application, such pressure being releasable to atmosphere back through conduit 45 and the exhaust port of the distribut ing or control valve under the control of said engineers brake v alve.

If wheel-spin should occur, however, such "as during initial application of propulsion power to the driving axles, due to some undesirable. condition, such as a wet rail, so that one pair of wheels on one of the designated pair of axles begins to spin, that is, said one axle rotates at a greater rate of speed than the other axle in said designated pair, the counter electromotive output of the motor driving the spinning axle exceeds that of the motor driving the other axle. In other words, assuming that the spinning wheels are the ones on the axle driven by motor 12,, said motor correspondingly gains in speed, as compared to the speed of motor 13 driving the axle on the non-spinning wheelsrto set up a higher counter eleetrornotive current. Therefore, an instantaneous potential difference at the inner terminals of the motors occurs with the result that current flows between the two motors via wire 23 and coil 22 or relay 14. With relay eoil 22 so energized, switch arm 24 is actuated to close the energizing circuit 9 to thereby efiect energization of the solenoid 26 of the solenoid valve device 10.

Upon energization of solenoid 26, valve member 27 is moved to'its unseated position in which fluid under pressure flows from main reservoir 4 to chamber 33 of the transfer valve device 5, as above described. Pressure of fluid in chamber 33 and acting on pilot piston 3 6 causes valve 37 to be shifted from its normal position to its change-over position in which chamber 3 of the brake cylinder device 1 is supplied with fluid under pressure from main reservoir 4, as above described. Since the fluid. in main reservoir 4 is maintained normally ata relatively. high pressure, such as L00 p.s,i. for Qx mple,

which pressure is far in excess of that required for actuating the. brake cylinder 1 during a spinning incident of the wheels, the pressure limiting device 6 is interposed in conduit 47 between said reservoir and transfer valve device Sand is adjustable for reducing the pressure of said fluid to a certain predetermined lower value as de sired, depending upon the type of braking equipment with which the invention is used. By way of example, the pressure limiting device 6 may be set to reduce the pressure to a certain value within a range of 10 to 20 psi. for effecting a relatively light brake application on the spinning wheels. The brake application, however, is momentary in duration because in the change-over position of valve 37 fluid under pressure from main reservoir 4 is also rapidly supplied to chamber 39 of the transfer valve device 5 and to timing volume 7 by way of

conduits

48 and 49, respectively, and through choke device 8, it being noted that valve 52 unseats to permit such rapid flowof fluid under pressure without restriction. Pressure promptly equalizes in chamber 3 of the brake cylinder device 1, in chamber 39 of the transfer valve device 5, and in timing volume 7, and when such pressure in said chamber 39 acting on control piston 38 has built up sufliciently to overcome the opposing force of fluid pressure acting on pilot piston 36, valve 37 is returned to its normal position in which fluid pressure in the brake cylinder device 1 is vented to atmosphere back through conduit 45 and the exhaust port of the distributing valve (not shown) to thereby release the momentary brake application.

Fluid pressure trapped in chamber 39 of the transfer valve device 5 and in timing volume 7, however, is allowed to vent back through choke device 8 only at the restricted rate determined by the adjustment of screw 55, above described. Therefore, if, after valve 37 has returned to its normal position, a difference in the respective rates of rotation of the two axles in the designated pair still persists, valve member 27 of the solenoid valve device 10 remains in its unseated position due to the continuance of energization of solenoid 26 and, therefore, fluid pressure from main reservoir 4 continues to act on pilot piston 36. The pressure acting on pilot piston 36, however, remains ineffective for again shifting Valve 37 to its change-over position until fluid pressure in chamber 39 and timing volume 7 has reduced sufliciently to render said pressure acting on said pilot piston effective for shifting valve 37 to its change-over position for again effecting a momentary brake application on the slipping wheel, in the manner above described.

Thus, as long as a difference in the respective rates of rotation exists between the two axles of the designated pair, the apparatus will function in a cycling fashion, as immediately above described, until both axles are rotating at synchronous rates of speed. It should be apparent, of

course, that it", upon completion of the first momentary brake application cycle, the spinning condition has been corrected or the two axles are rotating at synchronous rates of speed, valve 37 will remain in its normal position since solenoid 26 will have been deenergized and valve member 27 will have been restored to its normal position by spring 28 to cut off further supply of fluid pressure from reservoir 4 to chamber 33 which is vented to atmosphere via

passageways

32 and 34. It should also be apparent that the amount of lapsed time bet-ween each cycle of operation of the apparatus is determined by the combined volumes of chamber 38 of the transfer valve device 5 and the timing volume 7 and the setting of adjustment screw 55 of the choke device 8.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. Vehicle brake control apparatus comprising the combination of brake cylinder means for applying a braking force to vehicle wheels, a source of fluid under pressure, valve means having one position to which it is yieldingly biased and in which it establishes a first communication via which fluid under pressure may besupplied to said brake cylinder" means and released therefrom under manual control to effect application and release respectively of braking forces on the wheels, and a second position in which it closes said first communication and establishes a different communication via which fluid under pressure issupplied from-said source to-said brake cylinder means, two fluid pressure responsive means one of, which is subjectable to fluid under pressure i n a chamber at one side thereof to actuate said valve means from its said one position to, itsjsaid second position and the other of which is subjectable to fluid under pressure in a chamber at one side thereof to exert an opposing force on said valve means which causes restora tion of said valve means to its said one position, passage means providing communication via which fluid under pressure supplied to the brake cylinder means flows con currently to the chamber at one side of said other fluid pressure responsive means at an unrestricted rate and via which fluid under pressure is released therefrom'at a restricted rate upon release of fluid under pressure from the brake cylinder means thereby causing a cycling operation of said valve means between its said one and said second positions so long as fluid under pressure is supplied to the chamber at one side of said one fluid pressure responsive means, and a valve device having one position to which it is biased and in which it releases fluid under pressure from the chamber at one side of said one fluid pressure responsive means and being operative to a second position in which it cuts off the release of fluid under pressure from said chamber at one side of said one fluid pressure responsive means and establishes a communication via which fluid under pressure is supplied thereto.

2. Vehicle wheel-spin inhibiting apparatus comprising the combination of brake cylinder means for applying a braking force to vehicle wheels, a source of fluid under pressure, valve means having one position to which it is yieldingly biased and in which it establishes a first communication via which fluid under pressure is supplied to said brake cylinder means and released therefrom under manual control to effect application and release respectively of braking forces on the wheels, and a second position in which it closes said first communication and establishes :a different communication via which fluid under pressure is supplied from said source to said brake cylinder means, two fluid pressure responsive means one of which is subjectable to fluid under pressure in a chamher at one side thereof to actuate said valve means from its said one position to its said second position and the other of which is subjectable to fluid under pressure in a chamber at one side thereof to exert an opposing force on said valve means which causes restoration of said valve means to its said one position, passage means providing communication via which fluid under pressure supplied to the brake cylinder means flow concurrently to the chamber at one side of said other fluid pressure responsive means at an unrestricted rate and via which fluid under pressure is released therefrom at a restricted rate upon release of fluid under pressure from the brake cylinder means thereby causing a cycling operation of said valve means between its said one and said second positions so long as fluid under pressure is supplied to the chamber at one side of said one fluid pressure responsive means, second valve means having one position to which it is biased and in which it releases fluid under pressure from the chamber at one side of said one fluid pressure responsive means and being operable to a second position in which it cuts oif the release of fluid under pressure from the chamber at one side of said one fluid pressure responsive means and establishes a communication via which fluid under pressure is supplied thereto, biasing means for biasing said second valve means toward its said one position, and wheel-spin sensing means operable responsively to a spinning condition of the wheels for causing said second valve means to be operated to said one position and to termination of said spinning condition for rendering said biasing means eflective for restoring said second valve means to its said one position. v 3. The combination defined in claim 1 wherein the two fluid pressure responsive means have different respective pressure areas over which fluid under pressure in said chambers is effective.

- '4. The combination defined in claim -1 wherein the said other fluid pressure responsive means has a pressure area subjec'table ito fluid under pressure in the chamber on the one side of said other flu-id pressure responsive means and larger than the pressure area of said one fluid pressure responswe means. 1 r

5. "Ih ecornbination defined in claim 1 further character'ized by a separate timing volume of predetermined volumetric capacity connected to the chamber at one side of said other fluid pressure responsive means.

6. The combination defined in claim 1 furthercharacterized by a check valve and choke device interposed in said passage means for permitting unrestricted flow of fluid under pressure to the chamber at one side of said other fluid pressure responsive means concurrently with supply of fluid under pressure to the brake cylinder means and for restricting flow, in a reverse direction, of fluid under pressure from the chamber at one side of said other fluid pressure responsive means.

7. The combination defined in claim 5 further characterized by a check valve and choke device interposed in saidpassage means in'communication with said timing volume and with the chamber at one side of said other fluid pressure responsive means for permitting unrestricted flow of fluid under pressure to the chamber atone side of said other fluid pressure responsive means and to said timing volume concurrently with supply of fluid under pressure to the brake cylinder means and for restricting flow, in a reverse direction, of fluid under pressure from the chamber at one side of said other fluid pressure responsive means and from said timing volume.

No references cited