US2475783A - Control for air compressors - Google Patents

Description

July 12, 1949. A, P. @|550 2,475,783

' CONTROL FoR AIR coMPREssoRs I Filed Sept. 15, 1945 Patented July 12, y1949 CONTROL FOR AIR C'OMRESSORS Albert P. Gbbo, Los Angeles, Calif., assigner to Bryant Essick, Los Angeles, Calif.

Application September 15, 1945, Serial No. 616,539

(Cl. ZTL-53) 6 Claims.

This invention relates to a control for air compressors and relates, generally, to that type of apparatus known as a running unloader for air compressors. It is a general object of the present invention to provide an air compressor control which is simple, inexpensive and dependable and at the same time highly eiective in operation.

It is common, where air compressors, or the like, are employed, that the air be delivered by the compressor to a receiver or reservoir and control systems or running unloader controls are provided so that if the pressure in the receiver exceeds a predetermined value while the compressor is still operating the inlet valves of the compressor are opened, with the result that no further air is delivered by the compressor to the receiver. In practice the valve actuating units at the compressor, which are pneumatically cperated and which function to open the inlet valves of the compressor, are satisfactory and give little or no trouble. However, the control mechanism proper, that is the mechanism responsive to the pressure developed in the receiver, usually involves delicate, accurately formed members subject to failure or to inaccurate operation due to causes such as foreign matter lodging on them, etc.

It is a general object of my present invention to provide a control unit or mechanism responsive to air pressure from a receiver, or the like, which is operable to effectively admit air to work compressor valve actuators and which is entirely free of intricate, delicate or sensitive parts subject to failure or inaccurate operation.

A general object of my present invention is to provide a pressure responsive control of the general character referred to which is of the dia* phragm type, that is, which involves a diaphragm as the pressure responsive element and by thus employing such a member I eliminate entirely accurately tted pistons or delicately balanced valves, etc. generally required in mechanisms of the type referred to.

Another object of my present invention is t provide a control of the type mentioned including a simple, easily operated means whereby the control can be manually operated so that the inlet valves of the compressor are open whenever the operator desires, as for instance, when the compressor is being put into operation.

A further object of my Present invention is to provide a control of the general character referred to which involves but few simple, inexdependable in operation and economical of production.

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the ac companying drawings, in which:

Fig. 1 is a View showing a typical installation in which the control of the present invention can be advantageously used. Fig. 2 is a vertical detailed sectional View of the control that I have provided showing it in the normal or closed position, and Fig. 3 is a View similar to Fig. 2 showing the control actuated or open.

The control that I have provided can be used in various situations. However, it is particularly useful in the usual air compressor installation 'where an air compressor A is driven by a motor or engine B that delivers air through a delivery line C to a receiver D. In this sort of installation it is usually desirable that the motor or engine B operate continuously or at a substantially constant speed and rather than to attempt to control the delivery of air by means of controlling the prime mover the air compressor A is controlled. In such usual arrangements such as is shown in Fig. 1 a valve actuating unit E is provided in connection with each inlet valve of the air com pressor and a pressure responsive control mechanism F is provided to control admission of air under pressure from the receiver D to the units E.

The general scheme of operation of a hook-up such as I have just referred to is that when the compressor delivers an excessive amount of air to the receiver D an excess pressure develops in the receiver causing operation of the pressure responsive mechanism F which, in turn, admits air under pressure from the receiver D to the units E so that the inlet valves of the compressor A are held open. The result ls that no further air under pressure is vdelivered to the receiver D. The pressure actuated unit F is such that the foregoing condition prevails until such time as the pressure in the receiver D drops to the desired level or value, whereupon the units E release the linlet valve of the compressor A and air again is pumped into. the receiver D.

My present invention is concerned, primarily, with a pressure responsiv'eunit F and a preferred form of the invention is shown in detail in Figs. 2 and 3 of the drawings. It is to be. understood, however, that I do not wish my invention limited pensive parts, makina the mechanism as a whole. tel use in any specic situation such as I: have.

described above, as it may be used to advantage in various other systems or arrangements.

The device of the present invention, that is, the pressure responsive unit F that I have provided, includes, generally, a sectional body having a lower section I and an upper section II, a diaphragm I2 confined between the body sections, means I3 normally yieldingly holding the diaphragm in position to close ports of the lower or base section of the body, bleeding means I4 acting to normally bleed pressure from the units E y to the compressor A through the control F and by-pass means I5 whereby the control F can be manually operated to admit pressure from the receiver D to the units E to facilitate starting or other such operations.

The lower section I0 of the body includes, generally, a plate portion which may be a disc-like element round in plan conguration and provided with a flat top 2|. In practice I prefer to finish or machine the top surface 2I of the plate 2U as that is the part of the base section I0 with which the diaphragm cooperates. The base section II) includes a downwardly or axially projecting boss 22 in which there is an inletport 23 leading to the face 2| of the plate 29. A laterally projecting boss 24 is provided on the lower` side of the plate 20 joining the boss 22 and is provided with an outlet port that has an axial portion 25 communicating with the face pipe 29 and the outer portion of port 26 is ,5-1:I

threaded at 3i) to receive a discharge pipe 3l. The discharge pipe 3I in the arrangement illustrated extends to the units E of the compressor A whereas the inlet pipe 29 connects with the receiver D.

The upper or cap section II of the body has a plate portion corresponding, generally, in size and shape to the plate 29 of the lower section Iii, except that it is preferably somewhat thicker, as will be seen in sections 2 and 3 of the drawings. A central charnber or recess 4I is provided in the inner or under side of the plate 35 facing the diaphragm I2 to accommodate pressure plate 42 which is a part of the means I3. A boss 43 projects upwardly a substantial distance above the plate 35 and forms a spring chamber 44 to carry the spring 45 of means I3.

In accordance with my invention the diaphragm I2, which is a exible disc of suitable material, is made to correspond in size with theplates 29 and 35 and is arranged between the plates and is there secured by clamping the plates by means of screws 59, or the like. In the arrangement illustrated I have shown screws passed through openings in plate 35 and threaded into openings in plate I0. It will be apparent that any suitable means may be provided for tying or clamping the plates tight onto the diaphragm I2 so that the diaphragm is, in effect, clamped tight between the plates.

The means I3 provided for normally yieldingly urging the diaphragm down or into closed position includes, generally, the plate 42 carried in chamber 44, which plate bears on the top of the diaphragm, the spring 45 which acts on the plate 42 to normally urge it downwardly, and an abutment 5I against which the spring bears. The abutment is located in the upper end portion of the spring chamber 44 and is preferably adjustable.

In accordance with the preferred construction I adjust the abutment 5I by means of a screw 60 threaded through an opening in the top of the boss 43 which screw engages and defines the position of the abutment 5I. An operating knob or handle 6I is provided on the upper or outer end of the screw so that the adjustment can be readily made whenever desired.

The means I4 provided for bleeding pressure from the units E is an important feature of the present invention. In the preferred form of the invention this means is carried out by suitably porting parts that I have described, so that normally or when the control is in the position shown in Fig. 2 the outlet ports or port portions 25 and 26 are open to atmosphere and any air from the units E or the pipe connection 3| is free to bleed out through the control F to assure complete exhaust of pressure from the units E.

In the preferred arrangement illustrated in the drawings the porting includes a port 'I2 in the base section of the body extending from the port portion 26 to the marginal portion of the diaphragm that is clamped between the plates 20 and 35, a port i3 in the diaphragm I2 registering with and therefore communicating with the port 12, a port 'I4 in the cap section of the body registering with the port 'I3 in the diaphragm and extending to and opening at a slightly beveled portion 80 of i? the bottom face of the plate 35 immediately adjoining the chamber 4I and, therefore, at a point where it is open or uncovered when the diaphragm is down, as shown in Fig. 2, but is closed when the diaphragm is up, as shown in Fig. 3. There is an additional exhaust port in the cap 8l, as for instance, in the boss 43, so that air admitted into the cap through the ports 'i2y 'I3 and I4 is free to escape to atmosphere.

The system of porting just described is related f to the inlet and outlet ports in the base section so that the capacity of the bleeding means is considerably less than that of the inlet and outlet ports in the base section, so that pressure will build up causing the diaphragm to move definitely from the position shown in Fig. 1 to that shown in Fig. 2, rather than to merely leak out through the bleed means without causing operation suicient to cause the bleed means to be shut off, as

, shown in Fig. 3.

The `by-pass means I5 preferably includes a port in the wall 21 between the inlet and outlet ports provided in the bosses of the base section of the body. A seat 9| is provided in the port 9U n and a needle valve 92 is screw threaded in the boss 22 so that it can be moved into seated engagement with the seat 9| to close the port 90. A gland nut 93 may be provided around the needle valve to act on packing to prevent leakage around the valve.

In operation, assuming that it is desired to start the motor or engine B under minimum load, or in other words, without the compressor A acting to compress air, the needle valve 92 is opened so that pressure stored in receiver D or any pressure developing in the receiver D is by-passed from the inlet port 23 to the outlet port to pass through the pipe 3I to the units E causing the inlet valves of the compressor A to be opened. As soon as the unit is operating properly and when it is desired to put it into full operation under` automatic control the valve 92 is closed.

When pressure in the receiver D exceeds a predetermined value that pressure is communicated through the inlet pipe 29 to port 23 and acts under the diaphragm I2 to lift the diaphragm against the spring 55, the point at which this occurs having been set by the adjustment of screw 60. Prior to such lifting or opening of the diaphragm the diaphragm closes the inlet and outlet ports, or acts as a seal between the port 23 and the port section 25 so that no pressure is admitted from the receiver to the units E.

When the diaphragm l2 lifts or opens against the pressure of the spring 45, ypressure develops in the outlet port and in the outlet line 3|, and therefore units E, and this occurs in spite of the bleeder means Ill because the ports of the bleeder means are so small that air cannot escape fast enough to prevent such action. As soon as the diaphragm I2 has been fully lifted or operated, as shown in Fig. 3, the bleeder means is definitely cut off since the diaphragm closes the port 14 because the diaphragm moves up into engagement with the beveled face 80 of the plate 35 of the cap section of the body.

When the pressure in the receiver drops back to the predetermined value or point then the spring 45 overcomes the pressure under the diaphragm l2 and causes the diaphragm to be moved downwardly into engagement with the face 2| of the base section, thus closing oi communication between the inlet and outlet ports in the base section. As soon as this occurs pressure in the outlet port in the pipe 3| and units E bleeds out through the ports 12, 13, 14 and 8|. When the pressure is thus bled out of the system the units E are unactuated or, in other words, the inlet valves of the air compressor are freed or allowed to function in the normal manner.

Having described only a typical preferred form and application of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims:

Having described my invention, I claim:

1. A control of the character described including, a body having inlet and outlet ports, a flexible diaphragm normally cooperatively engaging the body and closing communication between the ports, a bleed port in the body normally open to bleed pressure from the outlet port, and means normally yieldingly holding the diaphragm in its normal position the diaphragm being operable relative to the body by pressure admitted through the inlet port to establish communication between the inlet and outlet ports and close the bleed port.

2. A control of the character described including, a body having inlet and outlet ports, a diaphragm normally cooperatively engaging the body and closing communication between the ports, a bleed port normally open to bleed pressure from the outlet port, a manually operable by-pass between the inlet and outlet ports, and means normally yieldingly holding the diaphragm in its normal position the diaphragm being operable relative to the body by pressure admitted through the inlet port to establish communication between the inlet and outlet ports and close the bleed port.

3. A control of the character described including, a body having inlet and outlet ports, a diaphragm having one side normally cooperatively engaging the body and closing communication between the said ports, means normally open to bleed pressure from the outlet port, and means normally yieldingly holding the diaphragm in its normal position, the rst mentioned means including a bleed port in the body located to be closed by the other side of the diaphragm when the diaphragm is operated relative to the body by pressure admitted through the inlet port to open communication between the inlet and outlet ports.

4. A control of the character described including, a body having a base section with a face and inlet and outlet ports extending to said face and a cap section, a ilexible diaphragm held between the sections, means carried by the cap section normally yieldingly holding the diaphragm in engagement with said face to cut olf communication between the ports, and means for bleeding pressure from the outlet port including a bleed port in the cap section located to be closed by the diaphragm when the diaphragm is actuated out of engagement with the face against the rst mentioned means.

5. A control of the character described including, a body having a base section with a face and inlet and outlet ports extending to said face and a cap section, a flexible diaphragm held between the sections, means carried by the cap section normally yieldingly holding the diaphragm in engagement with said face to cut off communication between the ports, and means for bleeding pressurev from the outlet port including a bleed port in the cap section smaller in capacity than the inlet and outlet ports and located to be closed by the diaphragm engaging the cap when the diaphragm is actuated away from said face against the first mentioned means.

6. A control of the character described including, a body having a base section with a face and inlet and outlet ports extending to said face and a cap section, a flexible diaphragm held between the sections, means carried by the cap section normally yieldingly holding the diaphragm in engagement with said face to cut off communication between the ports, a manually controlled by-pass between the inlet and outlet ports, and means for bleeding pressure from the outlet port including a bleed port in the cap section located to be closed by the diaphragm engaging the cap when the diaphragm is actuated against the rst mentioned means.

ALBERT P. GIBBO.

REFERENCES CITED The following referefnlces are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 572,580 Spitzenberg Dec. 8, 1896 686,779 Steedman Nov. 19, 1901 963,045 Hulse July 5, 1910 1,275,843 Callan Aug. 13, 1918 1,584,032 Hoffman May 11, 1926 1,771,410 Landis July 29, 1930 2,275,303 Mantle Mar. 3, 1942

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