US1847688A - Pneumatic control system - Google Patents

Description

March 1, 1932. A. c. OUWENHOVEN 8 PHEUIATIC CONTROL SYSTEI Filed 001:. 21, 1925 Patented Mar. 1, 1932 UNITED STATES;

PATENT OFFICE ABRAHAM CORNELIS-COUVFENHOVEN,OF BKDEN, SWITZERLAND, ASSIGNOR' TO AKTIEN- -G-ESELLSCHAFT BROWN, BOVERI AND CIE.; BADEN, SWITZERLAND PNEUMATIC conrnor. SYSTEM Application filed October 21, 1925, SerialNo. 64,053, and in GermanyfiOctober 30, 1924.

My invention relates to pneumatic control important that the control drum be moved in definite steps corresponding tothe different positions at which the drum establlshes the various operating circuits. Where the drum is pneumatically controlled, as by meansof a compressed air motor,-difficulti'es are encountered in bringing the control drum into the exact control positions since, on the one hand, there is an elastic after effect of the confined air used to move the controller, and on the other hand, the inertia of the moving masses makes it diflicult to bring them suddenly to a rest. Asa result, the several controlling positions of the prior art controllers of the foregoing type could not be accurately fixed, thereby complicating the operation of the apparatus intended to be controlled thereby. ent invention the foregoing difiiculties are eliminated by associating with thepneumatic motor apparatus, a mechanical locking device or detent so arranged as to positively mechanically lock the movement of the air motor and the associated control drum at the predetermined positions. trol the flow of the operating pressure fluid into the pneumatic motor are directly controlled by the mechanical locking device so that, when the locking device has arrested the movement of the motor at a predetermined point corresponding to a control position of the control drum, the fluid pressure condi-1 tions in the motor are such as to maintain it in a stationary condition. This is secured by utilizing the locking device or detentitself for operating the control valves of the.

air motor.

My invention will be best understood from the accompanying dra-wlng whlch- 1s a dlagrammatic vlew of the control system exem-j plifying my invention.

Although'my invention is not limitedthere- According to the pres The valveswhich conto,it has been developed principally in connection with'the railway control systems of the type such as described in Patent No. 1,323,301 of Paul L. Mardis. In such control systems the various circuits for operating the railway vehicle at 'aplurality of different speeds, according to the particular operating requirements, are established by means ofja control drum arranged to'be rotated in one direction or another direction by means of an air motor. The air motor is in turn controlled from'an auxiliary'controller actuated by the operatoro'f the vehicle, the controller serving to suitably direct the flow ofcompressed 'airor other pressurefiui'd into the air motor in order to bring the operatingmechanism thereof, with the associated control drum,'i nto the desired operating position.

A system of this type arranged'to embody my invention is diagrammaticallyillustrated in the'drawing. The control drumwhich is to be moved'between a plurality of control positions is indicatedat a and is rotated by means of an air motor which comprises a pair of air or'pressure fluid'cylinders b,0'withthe associated pistons transmitting their movement to the control drum a by means of a rack and pinion: gear d. The admission and escape of the compressed air into the cylinders or casings b and c of the air motor is controlled by a pair of main control valves 6 and .g. The main valve 6 'is commonly designated asthe off valve while'the other mainvalve g is commonly designatedas the on valve for reasons-explained hereinafter.

The two main valves 0 and g are heldpby means ofsprings f, in the positions indicated'inthe drawing'at which the compressed valve g cuts the cylinder 0 oil? fromthe compressed air supply and'the air confined in said cylinder is permitted to escape, causing clockwise rotation ofthe control drum (1, which rotation is 1ntended,'1n the present case, to

represent control action for energizing the vehlcle and ralsmg the speed thereofi On the otherhand release of'thespring f in the off valve 6 cuts the lefthand cylinder 6 off from the compressed air supply and the com-' pressed air confined in the said cylinder is permitted to escape thereby moving the con= trol drum counter clockwise towards the zero position at which the vehicle motors are deenergized.

To secure positive stoppage of the control drum at the desired control positions and to avoid, what might be called, blurred action of the prior art arrangements of the foregoing character, the control drum a with the associated air motor is provided with a mechanical locking device so arranged as to cause said drum to stop only at predetermined fixed positions and to positively preclude stoppage of the drum at a point somewhat in advance or somewhat back of the desired control position. In the exemplification shown 20' in the drawing thelocking device is shown in the form of a ratchet wheel it having a number of notches corresponding to the steps of the controller. A detent arm with a detent cooperates with the ratchet wheel h to either "lock the same at the positions corresponding lever 2' having a fixed fulcrum. The righthand end of the detent arm rests on a piston rod of an auxiliary air cylinder n while the lefthand arm of the lever i is actuated by the .piston of a second auxiliary air cylinder m. Suitable stops on the lever 2' and detent 7c act upon the main valve control levers 0 and p in opposition to the springs 7 thereof in order to connect the cylinders b and 0, respectively,

either to the compressed air supply or to the atmosphere. The piston of the auxiliary air cylinder m is loaded with a spring to pull the left side of the lever i downwardly so as to out OK the main air cylinder 6 from the compressed air supply and connect it with the atmosphere, and at the same time to lift the detent arm is, thereby unlocking the ratchet wheel 72,. However, it compressed air is admitted to the auxiliary air cylinder m, by

means of an auxiliary off valve 9, the lever is held in a raised position so that the cylinder 6 may communicate with the compressed air supply. The auxiliary oil valve 9 may in turn be controlled by means of an electromagnetic coil s. which is so arranged that, when said coil is energized, the valve 9 ad-,

mits compressed air to the auxiliary cylinder m, holding the associated lever arm in a raised position, and, when said coil is deenergized, the auxiliary valve 9 cuts the air supply off from the auxiliary cylinder m,

thereby leaving the loading spring free to pull the lever 2' downwardly and in turn cutting the compressed air supply 0E from the main cylinder 1). The piston of the righthand auxiliary air cylinder 12 isalso loaded and neath the detent.

' downward position.

held in downward position and is similarly controlled by an auxiliary on valve 7' which is in turn actuated by an electromagnetic coil 25-. The auxiliary on valve 9 with the associated actuating coil 17' is so arranged that, when said coil 2? is de-energized, the compressed air supply to the auxiliary cylinder n is cut oil so that the piston is held in the lowered position by the loading spring of the cylinder. If the actuating coil 13 is energized, the auxiliary on valve admits compressed air to the cylinder n, raising the piston and therethrough the detent arm is, thereby unlocking the ratchet Wheel h and also cutting off the compressed air supply from the righthand main cylinder 0 of the air motor.

The energiza-tion and de-energization or" the electromagnetic coils s and t, by means of which the arms of the combined locking and.

main valve control mechanism are actuated, is suitably controlled by the operator depending on the positioninto which he desires the main control drum (1 to be brought. The details of this part of the mechanism do not: constitute a part of my present invention and have accordingly not been illustrated. They are familiar to those skilled in the art.

The energizing circuit of the electromagnetic coil 6', by means of which the auxiliaryon valve 2 is controlled, includes an auxiliary switch M which is operated by the detent arm is so that when said arm is lifted, through the action of the piston in the righthand aux-- iliary cylinder n, the auxiliary switch is:

opened and the electromagnetic coil t is deenergized. Upon return of the piston in the valve cylinder at to the downward position and the subsequent lowering of the detent arm when the detent drops into a notch of the ratchet wheel 7L, theauxiliary switch a is again closed, thereby reestablishing the circuit to the electromagnetic coil 2/.

The mechanical connection between the main control drum a and the ratchet wheel it includes a resilient coupling means, such springs r, so arranged that when the detent arm 70 is momentarily lifted by the piston oi the auxiliary cylinder nand before said arm has time to follow the return movement of said piston, prompted by the de-energization oi" the magnetic coil 6 by reason of the interruption of the energizing circuit through the openingof the auxiliary switch ua tooth of theratchet wheel It will have run under-- Accordingly the detent will be held in raisedposition until it has reached the next it, although the piston of the auxiliary cylinder n has, in the meanwhile, returned to As long as the detent is in raised position, that is, until it dro s into the next notch of the ratchet wieel, the main on valve g is held in its raised position connecting the righthand main cylinder notchon the ratchet wheel 0' withthe compressed air supplyand disconnecting it from the atmosphere.

To explain theoperationof the foregoing system, let us assume vtheentire control system at rest, that is, that the main control drum has been brought to a definite operating position and is to be held therein. Under such conditions the several valves and the partso't the system will be in the positions indicated in the drawing, both main air cylinders Z) and 0 being iii-communication with the compressed air supply and, therefore, in a state ofequilibrium. At the same time the-detent in holds the ratchet wheel h in locked position, the off coil 8 isenergized andthe on coil 1- de-energized. I-fthe operator now desires to move the main control drum forwardly to oneof the higher speed positions, in the pres ent case in clockwise direction, he energizes the circuit of the ontcoilz. The on coil willthereupon cause the auxiliary on valve 1" to admit compressed air to the auxiliary on cylinder a, lifting the detent arm from the notch in the ratchet wheel h. The detent arm wil in turn act upon the main valve control lever 29 thereby opening the outlet of the main on valve 9 and cutting the air supply oii from the main cylinder 0. Consequently, the air in the lefth'and main cylinder 3) wil force the rack (Z to the right, thus-rotating the main drum a inclockwise direction.

Disregarding, for themoment, the absence of the auxiliary switch a in theenergizing circuit of the on coil t, the drum will continue to move until it'has reached the position desired by the operatorat whichtime the circuit of the on-coi-l t will be de-energized'. The auxiliary on valve 1" will thereupon drop into the position shown in thedrawing. releasing the compressed air from the auxiliary cylinder/n and leavinigthe detent free to drop downwardly to engage the next notch of the ratchet wheel,.thus mechanically locking the drum or atthe exactcontrol position into which it was desired to bringthe same. At the same time the righthand valve lever p is released, the main on valve 9 isthrown back into the position shown inthe drawing, reestablishing the compressed air supply to the cylinder c. Since the two main cylinders b and 0 are now again under equal air pressure, the rack d will no longer be under un balanced pressure and-equilibrium will be reestablished. 7

In many cases, as when the controller is advanced over a number of speed steps by a single setting of the controller the operator, it is importantthat the individual control steps shall be carried out distinctly. That is, it isoften desired thatthe controller shall move from step -'to step anditsmovement be momentarily arrested at the end of each step, and then proceed as if the operator actually intended movement over single steps only. Adistinctieature of thepresent invention is an arrangement for such controller operation and it is to thisend that I have provided the auxiliaryswitc'h u in the energizing circuit of the on coil t of the controller. In operation, with the switch it arranged asshown in the drawing and described hereinabove, the energizing circuit of the on coil t is interrupted each timethe detent is is lifted by the piston of the righthand auxiliary cylinder 70 from a notch of the ratchet wheel h. The de-energization of the on coil 25 immediately releases the air from the cylinder ncausing its piston to return to its zero position, in which it is shown in the drawing. In themeantime,the detent is has seated upon one of the teeth of the ratchet wheel h and is thus held in lifted position until said wheel has moved by a whole tooth corresponding to a full step of the controllerat which time the detent moves into locking position in the next succeeding notch under the action of spring Atthe endot the step, when the detent drops back into the next notch, the energizing circuit of the fon coil t is again completed and, if this position does notcorrespond to-that set by the operator, the cycle of operations recoms mences, the switch u being closed again and the magnet t energized thereby moving the rachet wheel h and the controller a by another step, and so on, until thedesiredposition is reached. To move the main control drum a in the opposite direction, in the pres ent case towardthe zero position of the drum, the off coil 8 is de-energized. This releases the compressedair fromthe auxiliary off cylinder m thereby'bringing the left-hand arm of the lever i to downwardposition. As a consequence, the righthand arm of thelever 2' will lift the detent is from the ratchet wheel, leaving the main drum or free to rotate, and, at the same time, the lefthand arm of said lever i will forcethe maincontrolling lever 0 of the main valve downwardly, cutting the compressed air supplyoff fromthe :lefthand main cylinder 6 and connecting it-to the exhaust. Consequentlygthe air in-the cylinder 0 will force therack (Z tothe left and this lefthand movement will continue until the piston has moved through its full stroke or until the magnet coil 8 is again energized. In the latter case the lever i is set free to return to its former position, as shown in thedrawing, which action does not take place, however, until the detent has come .oppositea notch in the ratchet wheel h at which point the ratchet wheel and the drumare locked and the main valve 6 again brought .to the position at which airequilibrium inthevtwo cylindersb ands-is reestablished. The foregoing arrangement, whereby the off coil s must beheld energized during the entire forward movement or while-the control drum occupies any of the forward positions, is very advantageous since it insuresthat, upon failure of the control-current supply, or any other accident of such nature, the detent is Will be mechanically raised from the ratchet Wheel 72. and the entire mechanism positively returned into its zero position.

The valve units 9 and 1" and the respective operating electro-responsive coils or elements 8 and 25 therefor constitute means common to the fluid motor and the holding or locking means -72 for controlling or governing the same, each of such units comprising, as shown, fluid inlet and outlet valves Which are opened and closed respectively upon excitation of the associated operating coil and which are closed and opened respectively upon deenergization of the latter. The arrangement, accordingly, is such that upon energization of each of the controlling or governing devices gs and rt release of the holding means kh and forward move ment or ope-ration of the motor is effected, While upon maintenance of energization of device gs and deenergization of device rt application of the holding means and non-operating or balanced-pressure condition of the motor is eflected, while upon deenergization of each of the controlling devices release of the holding means and reverse movement or operation of the motor is ei-- fected.

While I have described a specific form of my invention, it is not limited to the details shown and described, such as electromagnetic control of the mechanical locking device, etc., but is susceptible of many other modifications that will suggest themselves to those skilled in the art.

I claim as my invention:

1. In a controller system, a control member, a pressure fluid motor mechanism for moving said control member between a plurality of control positions, pressure fluid valve means controlling the movement of said pressure fluid motor mechanism, a mechanical locking device for arresting the movement of said pressure fluid motor mechanism, means actuated by said locking device to control said valve means, and means for effecting locking and unlocking action oi said locking device.

2. In a control apparatus, a control member, a pressure fluid motor mechanism for moving said control member to a plurality of definite control positions, pressure fluid valve means controlling the movement of said motor mechanism, amechanical locking device for arresting the movement of said control member in the predetermined positions, said mechanical locking device controlling said valve means to cause movement of said controller when in unlocked position, and means for unlocking or looking said locking device to control the movement of said controller member.

'3. Ina control apparatus, a control member, a fluid-pressure motor device for moving said control member to a plurality of predeterminedpositions, a mechanical locking device for locking said control member in the predetermined control positions independently of operation action of said motor, means actuated by said locking device for controlling the supply of fluid to and the exhaust of fluid from said motor in response respectively to unlocking and locking action of said device, and means for controlling said locking device.

4. In a control apparatus, a control memher, a motor for moving said control member through a plurality of steps to assume a plurality of distinct control positions, a mechanical locking device for mechanically locking said control member in any of the positions, means for energizing or Clo-energizing said motor in response to unlocking or looking action respectively of said device, means for holding said device in unlocked or locked position to control the movement of said con trol member, and means for causing step-bystep movement of said controller when controlled to move through a plurality of steps, said last-named means comprising means responsive to the initiation of a control step movement for causing said locking device to return to the locked position at the end of said step and responsive to the return of said locking device to the locked position for unlocking it to cause the following control step movement.

5. Apparatus as defined by claim 2 wherein the locking device comprises a member hav ing a plurality of notches and a detent arranged to engage said notches and characterized by two sets of means for eflecting movement of said detent out of operative relation with respect to said notched member, one set of such means causing movement of the control member in one direction and the other set of such means causing. movement of the control member in the opposite direction.

6. Apparatus as defined by claim 2 characterized by two sets of independently operable actuating means for said locking device each operable to effect unlocking action of the latter, one set of such means being operable to initiate operation of such apparatus in one direction and the other set of such means being operable to initiate operation of such apparatus in the opposite direction.

,. 2o 1. Apparatus as defined by cla1m 2 where 1 in .the locking device comprises a member having a plurality of notches, and a detent for engaging said notches to lock said device, said detent being arranged to be pivoted at two points, and characterized by means for pivoting said detent at one point to unlock the same and produce movement of the control member in one direction, and means for pivoting said detent at another point to unlock the same and produce movement of said control member in another direction.

8. In a control apparatus, a control member, a pressure fluid motor for moving said control member through a plurality of control steps to assume a plurality of distinct control positions, a mechanical locking device for arresting the movement of said control member in any of the control positions, means actuated by said locking device and responsive to locking and unlocking action thereof to control the movement of said motor, means operable to impart unlocking movement of said locking device and operable to control step-by-step operating movement of said control member with a distinct stop momentarily arresting such movement at the end of each step, and means operable to impart unlocking movement of said locking device and to control continuous return movement of said control member.

9. In a control apparatus, a control member having a zero position, a pressure fluid motor for moving said control member from its zero position through a plurality of control steps to assume a plurality of distinct control positions and to return the same to its zero position, a mechanicallockin'g device for arresting the movement of said control member in any of the control positions,-means actuated by said lockingdevice and responsive to locking and unlocking actions thereof to control the movement of said motor, control means operative to impart unlocking movement to said locking device. and operative to initiate movement of said control member away from the zero position, control means operative to cause movement of said control member to its zero position, and energy supply means for operating each said control means, the last said control means being operative to initiate operation of said control member to return to its zero position upon failure of said energy supply means.

In testimony whereof I have signed my name to this specification.

ABRAHAM CORNELIS COUWENHOVEN.

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