US2707456A

US2707456A - Reciprocating fluid pressure motor

Info

Publication number: US2707456A
Application number: US134983A
Authority: US
Inventors: Frederick G Schweisthal
Original assignee: Stewart Warner Corp
Current assignee: Stewart Warner Corp
Priority date: 1949-12-24
Filing date: 1949-12-24
Publication date: 1955-05-03
Anticipated expiration: 1972-05-03

Description

May 3, 1955 F. G. scHwElsTHAL 3,707,456

RECIPROCATING FLUID PRESSURE MOTOR May 3, 1955 F. G. SCHWEISTHAL RECIPROCATING FLUID PRESSURE MOTOR Filed Dec. 24. 1949 5 Sheets--ShemI 2 @lunar/716,155.

May 3, 1955 F. G. scHwElsTHAL 2,707,456

RECIPROCATING FLUID PRESSURE MOTOR Filed Dec. 24, 1949 3 Sheats-Sheet 3 United States Patent O 2,707,456 RECIPROCATING FLUID PRESSURE MOTOR Frederick G. Schweisthal, Skokie, Ill., assignor to Stewart- Warner Corporation, Chicago, Ill., a corporation of Virginia Application December 24, 1949, Serial No. 134,983

3 Claims. (C1. 121-134) My invention relates generally to reciprocating Huid pressure operated motors and more particularly to improved valve mechanisms for such motors.

In fluid pressure operated motors of the reciprocating type in which the lluid pressure is alternately supplied to the opposite ends of the motor cylinder through the `operation of a D slide valve, the speed of operation the ends of the cylinder without necessitating that it low through the D slide valve mechanism.

It is therefore a primary object of my invention to provide an improved fluid pressure operated reciprocating motor in which the back pressure on the air being exhausted from the ends of the inotor cylinder is reduced, and the efciency and speed of operation of the motor thereby increased.

A further object is to provide an improved valve mechanism for reciprocating pneumatically operated motors.

Other objects will appear from the following description,` reference being had to the accompanying drawings, in which:

Fig. 1 is an elevation of the motor, a portion thereof being shown in fragmentary section;

Fig. 2 is a central vertical sectional View of the motor;

Fig. 3 is an enlarged transverse sectional View taken on the line 3-3 of Fig. 1;

Fig. 4 is an enlarged sectional View -taken on the line 4--4 of Fig. 1; and

Fig. 5 is a fragmentary sectional View showing the detent means for the D slide valve operator.

The invention is illustrated as forming parl: of a lubricant pump having an operating rod and a cylinder 12. The pump maybe of any desired construction such as shown, for example, in the prior patent to E. W. Davis 2,406,747 or 2,060,180. The upper end of the operating rod 10 forms the piston rod of the motor piston 14 which is reciprocable in a cylinder 16 having heads 18 and 19 secured thereto by studs 20. A valve body 22 is secured to the head 18 by `studs 24. The valve body has a rD slide valve seat `plate 26 secured thereto, said

plate having ports

28, 29 and 30 formed therein. The port 28 communicates with a T-shaped passageway leading `to a check valve 34 which is held against a valve seat 36 by a light spring 38, the latter being held in place by a retainer pressed into the counterbored lower end of the passageway 32. A passageway 42 in the head 18 registers with the lower end of the passageway 32 and communicates, through a passageway 44 in ICC Ving to a check valve 54 similar to the check valve 34 previously described. The lower end of the passageway 52 is in registry with passageway 56 in the head 58 communicating with the upper end of the cylinder bore 48. A D slide valve 60 located in a valve chest 61 is reciprocable over the face of the valve seat plate 26 and has a portion fitting loosely in a chordal milled groove 62 formed in the valve operator sleeve 64 which is mounted for sliding movement in a bore 66 formed in the valve body 22. The upper end of the bore 66 is closed by a cap 63 secured to the valve body by studs 70. The piston rod 10 has a long bore 72 formed therein, the upper end of which is closed by a fitting 74 forming part of the piston 14 and through which projects valve stern 76 having a head 78 at the lower end thereof. The upper end of the valve stem projects through the head 18 and has an enlarged diameter portion Sil which is guided in the head 18, is sealed by a flanged washer 81, and projects into the bore 66 of the valve body 22.

The operator 64 has a central bore 82, the lower end of which has a shoulder 84 and the upper end of which has a sleeve S6 threaded therein. A pair fof Washers 88 and 39 are normally held in the positions shown in Fig. 2 in engagement, respectively, with the shoulder S4 and the sleeve 86 by a compressed coil spring 90. The upper end of the valve stem 76 has a head 92 riveted or otherwise secured thereto.

As indicated in Figs. 1 and 5, spring pressed ball detents 94 cooperate with

grooves

96 and 97 formed in the operator 64 to hold the latter, and thus the D slide valve 60, in either of two operative positions.

From the foregoing it will be clear that when the piston 14 nears the upper end of its stroke, the bottom of the bore 72 will engage the head 7S of the valve stem 76, and the enlarged diameter portion 81) of the valve stem 76 will engage washer 88 and move the latter upwardly against the force of the spring until the force exerted through the spring 90 is suiicient to overcome the restraining force applied by the spring pressed ball detents 94, or until a spacing sleeve 98 which surrounds the valve stein 76 between the washers 38 and 39 engages the washer 89, whereupon the operator 64 will be snapped to its upper position by the spring 94B, thereby changing the position of the D slide valve 60, and, as will hereinafter appear, venting the lower end of the cylinder and supplying air under pressure to the upper end of the cylinder to cause the piston 14 to commence its downward stroke.

Near the end of the downward stroke of the `piston the head 78 of the valve stem 76 is engaged by the tting 74 and the spring 90 again compressed. by downward movement of the washer 39 to overcome the restraining 'force of the spring pressed ball detents 94 and thereafter to cause the operator 64 to snap to its lowermost position in which it is shown in Fig. 2. Air under pressure is supplied to the valve chest or bore 66 through a suitable conduit 100 which is connected to `a supply tting 102 to which compressed air supply hose may be coupled.

Except for the provision of the check valves 34 and 54, the construction of the motor and valve mechanism, as thus far described, is substantially conventional. As best shown in Fig. l, the cylinder 16 is provided with upper and lower relief valve bosses 104 `and 105 which may be formed integrally with the cylinder 16. The relief valves in these bosses are identical and only the lower relief valve contained in the boss 105, which is `shown in Fig. 4, will be described. The boss S is provided with a passageway 106 which communicates with the lower extremity of the motor cylinder bore 48. The boss 105 is provided with an exhaust port 109 and a counterbore 108, the end of the latter forming a seat 110 for a relief valve 112 which has a valve disc 114 secured thereon, and has a piston part 116 which is slidable in the counterbore 108. A generally V-shaped packing ring 118 is loosely held between a pair of washers 120 and 121. The valve disc 114 is held against the seat 110 by a compressed relatively weak coil spring 124, which is seated in a bushing 126 threaded in the end of the counterbore 108. The bushing 126 has a tube 128 (Fig. 1) suitably connected thereto, the upper end of the tube being secured in an elbow 130 which is threaded in one end of the T-shaped passageway 32, Similarly, a conduit 132 connects the relief valve boss 104 to a fitting 134 which is threaded into a passageway 136 which is shown in phantom in Fig. 2 and communicates with the passageway 52.

When the D valve 60 is in its lower position, as shown in Fig. 2, air under pressure flows through port 28 and passageway 32, past check valve 36 and

passageways

42, 44 and 46 into the lower end of the motor cylinder bore 48. Air under pressure likewise flows through the conduit 128 to the relief valve counterbore 108 and thus holds the valve disc 114 against its seat, by virtue of the fact that the diameter of the piston 116 is greater than that of the end of the passageway 106 which is closed by the valve disc 114. At the same time the relief valve in the boss 104 at the upper end of the cylinder is forced from its seat, against the slight force applied by its spring 124, and the air under pressure above the piston 114 is rapidly vented to the atmosphere through its elbow shaped passageway 106 and its large exhaust port 138. This may take place because the conduit 132 is vented to the atmosphere through the D slide valve 60 and exhaust port 50. At the opposite end of the stroke of the motor piston 14 the D slide valve 60 is shifted to connect the conduit 128 to the exhaust port 50 and to permit air under pressure to flow from the valve chest 61 into the upper end of the cylinder through the passageway 52 and past check valve 54 while at the same time supplying air under pressure to the conduit 132 and the relief valve contained in the boss 104 at the upper end of the cylinder 48. The relief valve 112 in the boss 105 is thus free to open and permit the compressed air beneath the piston 14 to escape freely to the atmosphere through the associated passageway 106 and exhaust port 109.

It will be clear that by the use of the pressure relief valve 112, the operation of which is controlled by the D slide valve 60, the end of the cylinder to which air under pressure is not being supplied, is rapidly and efficiently vented to the atmosphere so that the back pressure on the piston 14 is greatly reduced. lt will be understood that the springs 124 of the relief valves are very light, being sufficient only to overcome the friction between the relief valves and the counterbores 108 in which they reciprocate so that the relief valves do not impose any substantial restriction nor do they materially impede the free discharge of air past them. Similarly, the check valves 34 and 54 are held against their seats by the relatively weak springs 38 and thus do not impose an appreciable Vrestriction to the free flow of air past them.

While I have shown and described a preferred embodiment of my invention, it will be apparent that numerous variations and modifications thereof may be made without departing from the underlying principles of the invention, I therefore desire, by the following claims, to include within the scope of the invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

l. In a compressed air operated motor, a motor cylinder, a piston reciprocable therein, a D slide valve mechanism operated by the piston alternately to admit air under pressure to the opposite ends of the cylinder, check valves to prevent return flow of air from the ends of the cylinder to the D slide valve mechanism, means forming a relief port at each end of the cylinder for freely exhausting air therefrom to the atmosphere, relief valves normally closing said relief ports, a pneumatic operator for each of the relief valves operable when supplied with air under pressure to maintain the relief valve closed, and means for conveying air under pressure from the valve mechanism to the pneumatic operator associated with the relief valve at the end of the cylinder to which air under pressure is being supplied through the valve mechanism.

2. A compressed air operated motor comprising a cylinder, a piston reciprocable in the cylinder, means forming passageways leading to the opposite ends of the cylinder, a Valve mechanism operated by the piston at the ends of its stroke alternately to supply air under pressure to said passageways, a check valve in each of said passageways, an exhaust valve at each end of the cylinder providing a relatively largev vent for the discharge of air to the atmosphere, light springs biasing the exhaust valves to closed position, pneumatic motor devices connected respectively to the exhaust valves to hold the latter closed, and air conduits respectively connecting said passageways leading to the head end and rod end of the cylinder with the pneumatic motor devices associated with the exhaust valves at the head end and rod end of the cylinder, the connections of the conduits to the passageways being at the inlet sides of the check valves in these passageways.

3. A valve apparatus for a fluid pressure operated reciprocating motor having a cylinder and a piston reciprocable in the cylinder, comprising means forming an exhaust port and two passageways respectively connected to the opposite ends of the cylinder, a two-position valve for alternately connecting one of the passageways to a source of fluid under pressure while connecting the other passageway to the exhaust port, check valve means respectively in said passageways for permittingv fiow of air under pressure toward the ends of the cylinder but preventing flow in the opposite direction, means operated by the piston for shifting the valve from one position to the other near the end of the piston stroke, means forming a fluid pressure relief port at each end of the cylinder, a relief valve for each of said relief ports, a fluid pressure operated actuator for each of the relief valves operable to close the valve when subjected to the motion of fiuid under pressure, means connecting the actuator for the relief valve at the head end of the cylinder to the passageway leading to the head end of the cylinder, and means connecting the actuator for the relief valve at the rod end of the cylinder to the passageway leading to the rod end of the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 37,186 Walters Dec. 16, 1862 259,432 St. John lune 13, 1882 400,323 Gever Mar. 26, 1889 417,329 Marsh, Jr. Dec. 17, 1889 554,364 Getty Feb. 11, 1896 816,348 Miller Mar. 27, 1906 1,304,286 Emden May 20, 1919 1,348,672 Wainwright Aug. 3, 1920