US2478116A - Reversing valve mechanism for power-operated vacuum pumps - Google Patents

Description

E. s. MARIOTTE 2,478,116 REVERSING VALVE MECHANISM FOR POWER OPERATED VACUUM PUMPS Aug. 2, 1949.

Filed March 27, 1946 3 Sheets-Sheet 1 IN V EN TOR.

Euyezre JJYariofie, BY

Aug. 2, 1949. 5, RIOTTE 2,478,116

REVERSI VAL MECHANISM FOR POWER RATEP VACUUM PUMPS Filed March 27, 1946 3 Sheets-Sheet 2 I 4 INVENTOR. ,5 1492110 ijya 'z'ofie E. S. MARIOTTE REVERSING VALVE MECHANISM FOR POWER OPERATED VACUUM PUMPS Aug. 2, 1949.

Filed March 27, 1946 JlE- E 3 Sheets-Sheet 3 INVENTOR.

ATTO/V/VEFJ.

Patented Aug. 2, 1949 REVERSING VALVE POWER-OPERATED VACUUM PUMPS Eugene S. Mariette, Syracuse, N. Y., assignor to Lipe-Rollway Corporation, Syracuse, N. Y., a corporation of New York Application March 27, 1946, Serial No. 657,492

2 Claims.

This invention relates to reversing valves for reciprocating motors, and has for its object a valve mechanism which operates or reverses with a snap action, and is particularly adapted for use in vacuum pumps, which embody a double acting piston motor for actuating a double acting pump piston, in which the amount of vacuum controls the operation of the power motor, stopping it when the vacuum reaches a predetermined value greater than the pressure of motive fluid or air which actuates the power motor, and permitting the power motor to start when vacuum is reduced and the pressure in the power cylinder is greater than the retarding eiiect of the vacuum, which mechanism in addition to giving a quick opening and closing of the ports through which the motive fluid flows to and exhausts from the motor, also prevents stopping of the valve in an intermediate or dead center position upon stopping of the motor, so that the motor will always start and continue running when the force of the vacuum is less than the pressure of the motive fluid in the power cylinder. As is known, the pressure in the power motor is controlled through a pressure regulating valve set to pass to the power motor, air at a predetermined maximum pressure. This valve mechanism is particularly designed for creating vacuum to withdraw the push piston or plunger in a stock bar feed for automatic metal working machines, where the push piston is under power pressure in a cylinder to feed the bar and is withdrawn by vacuum when the bar is used up or too short, to permit a new bar to be inserted in the cylinder in front of the plunger. For example, see Mariotte Patent No. 2,327,916 granted August 24, 1943.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

Figure 1 is a plan view of a vacuum pump equipped with this reversing valve mechanism.

Figure 2 is a longitudinal sectional view taken centrally of Figure 1.

Figure 3 and 4 are transverse sectional views taken on the planes of lines 3-3 and 4-4, respectively, of Figure 1.

Figure 5 is an enlarged exploded isometric view of a reversing valve.

Figures 6 and '7 are transverse views showing the position of the movable valve member at different points in the operation of the valve.

This valve mechanism for double acting cylin- MECHANISM FOR der and piston'motors includes, generally, a driving rocking element connected to a reciprocating part of the motor, as the piston rod, to be rocked thereby when the motor is in operation, a second or driven rocking element actuated by the first through a lost motion in either direction, a valve member shiftable by the second rocking element to be reversed in either direction thereby, and means energized by the first rocking element to actuate the second rocking element in either clirection, after the 10st motion between the two elements is taken up. The valve mechanism is here shown as embodied in a vacuum pump unit.

I designates the cylinder, and 2 the piston of a reciprocating motor carried by a frame 3 of any suitable construction. 4 designates a pump cylinder also carried by the frame 3 having a double acting piston 6 working therein, the cylinder i being carried by the frame 3 in axial alinement with, but axially spaced from, the power cylinder I. The pistons 2 and 6 have a piston rod l in common. 8 designates the valve mechanism as a whole, this being mounted on the frame 3 between the opposing ends of the cylinders l and 4 and 1 includes a suitable casing or body 8 mountable on the main body 3 between the cylinders and being here shown as a separable unit from the body 3. The casing is formed with a valve chamber l8.

H and. 12 are parts of driving and driven rocking elements mounted, and here shown as coaxially arranged, on the casing 9, the first element ll including a rock arm HA rotatably mounted concentric with the second element l2 which includes a spindle or shaft lZA rotatably mounted in a bore or bushing Hll located in the bore in the casing 9 coaxial with the valve chamber id. The spindle or shaft IZA extends into the valve chamber Ill and has a valve member or head l3 thereon which rocks therewith, the head 13 coacting with a stationary valve member or disk I l in the bottom of the chamber and being vir tually part of the frame 3.

l5 designates an arm which is a component part of the first rocking element. It is mounted to rock idly about the bushing or sleeve lit. 15 designates a pair of spaced apart rock arms mounted on the outer end of the spindle IZA to rock therewith. It constitutes a part of the driven rocking element 12. Spaced apart stops or lugs I! are provided on the rocking arm HA between which the arm l5 extends, the lugs being spaced apart a greater distance than the width of the arm I5. The pair of rocking arms 56 are also arranged in the path of movem nt of the arm [5 and are spacedapart a greater distance than the width of the arm l5, so that there is a lost motion connection between the arm 15 and the arms 16 in either direction of the rocking movement. When the driving rocking element i! or the arm I IA is rocked from the piston rod i, one or the other of the arms I? transmits the motion thereof to the arm in one direction, the arms remaining stationary. As the arm l5 approaches one of the arms I6, taking up the lost motion between them, an actuator is energized which re-acts on the arm it after it has been moved by the arm H A a predetermined distance and encounters one of said arms it under the reaction and operates the driven rocking element and the valve head with a snap action. During the snap action, the arm It moves out of engagement with the lug with which it was engaged, into engagement with the other lug. The means for timing this snap action includes inclined cam or plane surfaces l8 provided on the arm It or the hub thereof, these surfaces being wedge faces which meet at an apex or point H]. The actuator is a spring-pressed follower 2E3 movable in a suit able guide 2! carried by the casing 9. The follower is preferably provided with a roller or antifriction member 22 which coacts directly with the cam surface it. The rocking element is actuated from the piston rod l, and as here shown, the arm i HA at the end thereof extends over the piston rod '5 and is provided with spaced apart pins 23 which form a fork arranged astride a collar, as 2 3, on the piston rod 7. As the piston rod shifts axially in either direction, one of the lugs or stops l'l moves the arm is idly, and in so doing moves one or the other of the cam surfaces E8 (in accordance with the direction of the rocking movement) along the roller 22 and follower 26, thus moving the follower against the action of its spring. The driven element it remains stationary. However, as the arm It moves toward one of the arms 16 of the driven element, the apex 13 of the cam passes over the roller from one side to the other thereof, so that the spring of the follower 2B re-acts and the follower or its roller presses against the cam surface it on the other side of the apex, and hence crosses the driving rock arm it which in the meantime has moved up toward the rock arm I6 with a snap action. Hence, the valve I3 is reversed with a snap action. During this snap action, the arm it takes up the lost motion between the stops ll and hence reverses so as to be in position relatively to the arm HA to be driven in the reverse direction, when the valve reverses.

The valve members themselves may be of any suitable construction. As here shown, the stationary valve member M is provided with an air intake port 26 and ports 27 and 28, which are connected by bores or passages 29 and 3t] to ports at opposite ends of the power cylinder I. The stationary member I4 is also formed with exhaust ports 32, 33 which open into exhaust passage St to the outer air common to both. The movable or rockable valve member I3 is formed with transfer passages 35 and 38 in its face opposed to the face of the stationary valve member i l. The intake port 26 is connected to an intake bore 37 for connection to a source of supply of compressed air, by a suitable pipe having a suitable On and Off valve therein.

In Figures 2 and 6, the piston 2 is shown as at the end of its power stroke to the right and the valve has reversed to let the power pass through the right end of the cylinder I and exhaust from the left end of the cylinder I, so that the air will 4 pass from the inlet port 26 into the transfer passage 35 out through port 21, passage 29 into the cylinder l at the right end thereof to actuate the piston 2 to the left end. At the same time the left hand end of the cylinder is opened to exhaust through the passage 30, port 28, transfer passage 36 of the movable valve member it out through exhaust port 33 to exhaust passage as. When in this position, exhaust passage 32 is closed. During the movement of the piston to the left, the rocking element H is rocked carrying the rock arm [5 to the left or clockwise in Figure 5, until it picks up the left hand rock arm it on the spindle l2, and during this movement, cam surfaces l8 have moved so that one of them loads the spring for the follower 20, and further so that the point of the apex [9 of the cam becomes centered with the follower 29 or the roller 22 thereof, whereupon the spring of the follower re-acts to move down the other cam surface [8 and rock the driven element l2 with a delay snap action to reverse the valve member I3. p this reversal of the valve member it, it takes the position shown in Figure 7, wherein the left hand end of the cylinder I is open to the intake of air and in the right hand e d f h cyl nder l i pen to exhaust through the passage 29 and exhaust port 32, exhaust port 33 being then closed. The arm I IA which coacts with the piston rod l is virtually a driving member, and the member It, a motion transmitting arm actuated by the member HA through one or the other of spaced lugs IT to transmit the motion to the driven element, which is the element l2 including the shaft lllA, through the arms .16, The w e-p s d plunger 20 constitutes means coacting with the oppositely inclined cam faces 18 on the motion transmitting arm l5 which terminate in an apex or point at is, to actuate the motion transmitting arm [5 with a delayed snap action, and hence actuate the arm is, shaft IZA and the valve head. [3, with a snap action, when the driving element II or the components HA and !5 thereof have been actuated to shift the arm it from one arm I6 toward the other, 50 that the follower E1 is on' the point or apex 19 of he cam, and hence works the motion transmitting member l5 with a snap action, and hence actuate the valve head is with a snap action, This means, therefore, always locates the valve head I3 under stalled conditions where the motor will start against and not remain stalled or in dead center, when the predetermined air pressure in the power cylinder predominates over the vacuum in the pump cylinder or in the tank in which the vacuum is created. By reason of this valve, the vacuum automatically controls the operation of the power cylinder to automatically start and Work when the vacuum falls below a predetermined value and stop when the vacuum is at a predetermined value.

The vacuum pump .or the cylinder thereof is provided with a check valve 38 at each end thereof for permitting the escape of air when the vacuum is on the other side of the piston, and also with a check valve 3.9 at each end open-- ing inwardly and both connected to the tank chamber or other device from which the air is being evacuated by the piston. While the piston 6 is moving to the right end .Of the cylinder l into the position shown in Figure 1, the air on the right hand piston is free to exhaust through the right hand check valve 38 while suction is being produced on the left hand side of the piston 6 through the valve 39. During the movement of he piston 6 to the left. the air n the left side of the piston exhausts through the left hand valve 38 while suction is being produced on the right hand side of the piston 6 through the right hand check valve 39.

This pump is a particularly simple, compact unit and the valve mechanism a particularly compact unit in itself and combined with the cylinder and piston arrangement of the motor and the pump.

What I claim is:

1. A reversing valve mechanism for double acting cylinder and piston motors for controlling the fiow of motive fluid to and from opposite sides of the piston of the motor, the valve mechanism including a body having a valve chamber therein, a driving rock arm having means for connection to a part actuated by the piston of the motor to be actuated thereby, a driven shaft mounted in the valve casing and extending into the valve chamber, a valve member mounted on the shaft in the chamber, the driving rock arm being mounted to rotate about the aXis of the shaft relatively thereto, a motion transmitting rock arm mounted coaxial with the shaft to rock relatively thereto and a pair of rock arms mounted on the shaft and extending on opposite sides of the former rock arm' and spaced apart a distance greater than the width of the former rock arm, stops on the driving arm between which the motion transmitting rock arm extends, the motion transmitting rock arm having inclined cam surfaces which meet and form an apex, and a springpressed follower coacting with the cam surfaces and arranged to act on one or the other of the cam surfaces to shift the motion transmitting rock arm with a snap action when the apex of the cam passes over the follower.

2. A reversing valve mechanism for vacuum pumps which include a double acting cylinder and piston motor and a double acting reciprocating pump actuated by the piston of the power motor, the valve mechanism controlling the flow of motive fluid to and from opposite ends of the cylinder of the motor; said valve mechanism including driving and driven reversely movable elements, and a motion transmitting member between them, and means controlled by the motion transmitting member to actuate the driven element only when the driven element is approaching the end of its movement in either direction, to actuate said motion transmitting member relative to the driving and driven elements to reverse the valve mechanism with a snap action after the motor and valve mechanism have been stalled by the vacuum in the pump cylinder overcoming the pressure of the motive fluid in the power cylinder and the vacuum decreases where it is less than the pressure of the motive fluid on the power piston, said motion transmitting member being arranged to move as a unit with the driving element in either direction and also relatively thereto and being provided with oppositely inclined cam faces meeting at an apex, and said means including a spring-pressed follower movable along one of the other of the cam faces during the movement of said motion transmitting member by the driving member in either direction and operating to shift with a snap action when the follower rides on the apex of the cam.

EUGENE S. MARIOTTE.

REFERENCES CITED The following referemces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 884,131 Compton Apr. 7, 1908 2,318,782 Jorgensen May 11, 1943 FOREIGN PATENTS Number Country Date 541,214 Great Britain Nov. 18, 1941

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