US2406747A - Pneumatic motor - Google Patents

Description

Sept. 3, 1946. E. w. DAVIS PNEUMATIC MOTOR 2 Sheets-Sheet 1 Filed Ju ne 15, 1945 S p 1946- E. w.'DAv| s 2,406,747

- PNEUMATIC MOTOR Filed June 15, 1945 2 Sheets-Sheet 2 96 7,3 A 82 v I 4 I -70 88 v al Patented Sept. 3, 1946 UNITED STATES PATENT OFFICE 2,406,747 PNEUMATIC MOTOR Ernest W. Davis, River Forest, Ill. Application June 15, 1945, Serial'No. '599,664

- 1 7 My invention relates generally to pneumatic motors, and more particularly to improved valve mechanisms therefor.

It is an object of my invention to provide an" 4 Claims. (Cl. 121-164) Fig. 1 is a central vertical sectional view of the improved lubricant compressor and pneumatic motor;

Fig.- 2 is a plan view thereof:

Fig. 3 is an enlarged fragmentary sectional view of the valve mechanism, showing the positions of the valves during the downstroke of the motor piston; and

Fig. 4 is a similar view showing the positions of the valves on the upstroke of the piston.

Referring to Fig. 1, the airmotor is illustrated as forming a part of a lubricant pumping mechanism customarily termed a barrel pump, since it is adaptedto remove oils and greases from barrels and drums in which the lubricants and similar products are shipped. This compressor is shown as comprising a cylinder I6 which is secured to a cover I2 of an oil drum M, the

cylinder l0 extending to the bottom of the drum and having inlet ports l6 normally closed by a foot valve I 8. A piston is reciprocal in the cylinder l0 and is secured to a piston rod 22. Ports 24 in the piston 26 are adapted to be closed on the upstroke of the piston by a check valve 26. The piston rod extends through a head 28 at the upper end of the barrel Ill, a suitable pa ki 'gl 30 being provided. The lubricant is discharged from the barrel l6 through a pipe 32.

A motor cylinder body 34 is preferably cast integrally with pedestals 36 which have foot pertions 38 clamped to the end of the barrel ID by cap screws 40, which also secure the head 28 to the'end of the barrel. A valve actuating arm 42 is clamped against a shoulder 44 formed on the piston rod 22 by a. sleeve 46. Against the upper end of the latter there is clamped apiston 48, the-clamping being effected by a nut 50 threaded at the upper end of therod 22.

A cylinder head 52 is suitably secured to the upper end of the cylinder body casting 34, this head being provided with a passageway 54 leading from a lower valve chamber 56 to the upper end of the cylinder bore 58. The head 52 also has a passageway 60 leading from an upper valve chamber 62 to the lower end of the cylinder bore 56 through a connecting passageway 64 formed in the pump body casting 34.

The bod casting 34 has a sidewardly extending flange portion 66 provided with a valve seat 68. A second valve seat 10 is formed between the lower valve chamber 56 and upper valve chamber 62. The upper valve chamber is threaded to receive a cylindrical bushing 12.

The valve assembly comprises a poppet type valve 14, for cooperation with the valve seat 68, and a secondpoppet valve 16, for cooperation with the valve seat 'Hl.v The valve 14 is preferably formed integrally with a valve stem 86,

while the poppet valve 16 is clamped against a shoulder on the valve stem 86 by a sleeve 82 threaded on the upper end of the stem 80. A 1

cup leather piston 84 is slidable in the bore of the cylinder bushing 12 and is clamped between the sleeve 62 and nuts 86 threaded on the upper end Of the valve stem 80.

The valve stem is guided for longitudinal sliding movement in a bushed boss 88 forming part of the pump body casting 34. The lower end portion 90 of the stem 80 is of reduced diam eter and has a pair of helical springs 92, 93 held thereon, the spring 92 operating to transmit force from the arm 42 to an adjustable stop 94 on the valve stem, while the spring 93is adapted to transmit force from the arm 42 to an adjustable stop 96.

The operating fluid is supplied to the upper valve chamber 62 through an inlet pipe 98 provided with a shutoif valve I66.

In using the apparatus, the operating fluid, such as compressed air, is supplied to the upper valve chamber 62 upon openin the shutoff valve I00. Assuming that the valve assembly and piston 48 are in the positions shown in Fig. 1, the air under pressure will flow past the poppet valve 62 into the lower valve chamber 56, which is always in communication with the upper end of the cylinder 58. Thus air under pressure will be supplied to both the upper and lower ends of the cylinder 53, since it is clear that the lower end of this cylinder is at all times in communication with the upper valve chamber. However, due to the fact that the sleeve 46 is of substantial cross sectional area, it will be apparent that the effec- O tive area of the upper surface of the piston 48 is much greater than that of its lower surface, and therefore the piston 48 will be moved downwardly under the influence of the difference between the forces applied to its upper and lower surfaces by the compressed air. Upon downward movement of the piston 48, lubricant contained within the lower end of the barrel II) will flow through the ports 24 of the piston 20, raising the check valve 26, and some of thembricant will be discharged through the pipe 32, due to its displacement by the portion of the piston rod 22 which enters the barrel I0. When the piston 48 approaches the end of its downstroke, the arm 42 will engage the spring 93 and compress the latter until suificient force is applied to the valve stem 80, 90, to snapthe valve assembly from the position in which it is shownin Figs. 1 and 3 to the position in which it is shown in Fig. 4.

It will be noted that when the valveis in the position of Figs. 1 and 3, the pressure of the operating fluid is exerted'on the balancing cup leather piston 84' as well as over theefiective area of the valve 14. However, because the diameter of the piston 84 isgreater than that of the valve 14, the operating fluid will apply a net force to the valve assembly inan upwarddirection.tohold it inthe position in which it .is shown in Figs. 1 and 3. However, as the spring v93 becomes compressed further toward the endof the downstroke of the motor piston 43, the force of the compressed air holding .the .valve assemblyin its upp r. position will be overcome; As soon as the valve 14 leaves its seat, the, pressure inthe lower valve chamber 5 6 will drop and the force of thecompressed air acting Qntopoi the poppet valve it, as well as the force, of the compressed spring. 93, will be effective rapidly to snap the valve assembly from the position shown in Figs. 1 and 3, to the position shown in Fig. 4.

Whenthe valve mechanism is in the position shown in Fig. 4, air under pressure flows from the upper valve chamber 62 through the passageway 6,0, 6 4, to the lower end of. cylinder. 58. thesame time, the air in the upper end of the cylinder 58 is free to escape tolthe atmosphere through passageway .54, loWer. valve chamber 56, andthrough the port at the valve seat 68.

It will be noted that the effective area of the poppet valve 16 and of its seat. 10 is slightly greater than that of. the bore in the cylinder bushing 12, andthus the air will exertv a net. downward pressure onthe valve assembly. This pressurewill be su flicient to holdthe valveassembly.

in the position in which it is shown in Fig. 4. Thus the motor piston 48 will be moved upwardly. During the upward stroke, the lubricant pump valve 26 closes and the lubricant above'the piston 2|] is discharged through the pipe 32. Also durll'lg this upward stroke, the foot valve 16 opens to admit lubricant. As the piston 48 reaches the upper end ofv its stroke, the spring 92 is brought into-engagementwith the adjustable stop 94 and c mpressed until it applies sufiicient force to the valyestem 89,90, to move thelatter to its upper position, as shown in Figs. 1 and 3, thus completing a cycle of operation,

Due to the fact that the valves 14 and 16 are of the poppet type, and due to the use of the cup leather piston 84, the valve mechanism need not be manufactured with a very high degree of precision, and due to the successive decreases in diameter; of the valve seat 1! the bore of the,

linder ushin andthe v lveseat 68.110. de-,

tent means are required to hold the valve in its two operating positions. The dimensions of the latter parts are such that the valve will not move accidentally due to vibration, and yet sufficient force is applied to hold the valve assembly in its two operative positions so that the valve will operate with a snap action.

Whilel 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 b which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

1. In a fluid pressure operated motor, the combination of a motor cylinder, a motor piston reciprocable therein, a piston rod of substantial effective cross sectional area with respect to that of the piston, and valve means forcontrolling the supply of fluid to the opposite ,ends of said cylinder, said valve means comprising two chambers respectively in communication with opposite ends of said cylinder, a first valve seat providing a relatively small diameter outlet port, leading from the first of said chambers to the atmosphere, a second valve seat intermediate said valve chambers, the other of said chambers having a cylindrical bore open to the atmosphere, said bore being of slightly less cross sectional area than said second valve seat, and being of substantially greater cross sectional area than said first valve seat, a valve assembly having poppet valves respectively coo-perable with said valve seats andv having a piston reciprocable in said cylindrical bore, and means operated by said motor piston to move said valve assembly in the direction of piston movement near the end of each stroke of the motor piston.

21A valve mechanism for fluid operated reciprocating piston and cylinder type motors comprising, means forming a pair of valve chambers communicating with the opposite ends of the motor cylinder, having a first valve seat inter,-

med-iate the chambers, a balancing piston having one side thereoi exposed to pressure in one of said valve chambers and having its other side exposed to atmospheric pressure, a second valveseat forming' an air outlet port leading from the other of said'valvechambersto the atmosphere, a second. valve rigidly connected: to said first valve and to,

saidpiston and cooperable with said second valve seat, said valves operating in opposite directions.

otheris fully opened.

3."In a valve mechanism for a fluid operated motor having acylinder anda piston reciprocable therein, a valve. body providing a first chamber and a second chamber, means; connecting the first and spaced so that when one valve is closed the.

chamber to a source of fluid under pressure means respectively connecting said chambers tov the opposite endsof the motor cylinder, the first of said chambers having a cylindrical bore leading to the atmosphere at. one side and a valve seat of greater diameter than said cylindrical.- bore at. the other side, said second valve 'cham,. her having an outlet port, of smaller diameter. than said cylindrical bore leadingv therefrom to he at os er a va ve ass mb y m rising a. piston member slidable in the cylindrical bore,.a. p p t valve 00p a e;with..tne yalve.s. at, .and-

a second poppet valve for closing the outlet port, said poppet valves closing upon moving the valve assembly in opposite direction and being spaced apart so that when one valve is closed the other is opened, and means for reciprocating said valve assembly in response to movement of the motor piston near the ends of its forward and return strokes. v

4. In a valve mechanism for a fluid operated motor having a cylinder and a piston reciprocable therein; a valve body providing a first chamber and a second chamber; means connecting the first chamber to a source of fluid under pressure; means respectively connecting said chambers to the opposite ends of the motor cylinder; the first of said chambers having a cylindrical bore leading to the atmosphere at one side and a valve seat of greater diameter than said cylindrical bore at 6 the other side; said second valve chamber having an outlet port of smaller diameter than said cylindrical bore leading therefrom to the atmosphere; a valve asssembly comprising a piston member slidable in the cylindrical bore; a poppet valve 00- operable with the valve seat, and a, valve stem secured to said piston member and said poppet valve, said valve stem having formed thereon a second poppet valve for closing the outlet port, said poppet valves alternately closing upon moving the valve assembly in opposite direction and being spaced apart so that when one valve is closed the other is opened; and means for reciprocating said valve assembly in response to movement of the motor piston near the ends of its forward strokes.

ERNEST W, DAVIS.

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