US2722395A - Inlet control valves for air or other gas compression or vacuum pumps - Google Patents

Description

Nov. 1, 1955' G. B. BOYCE 2,722,395

INLET CONTROL VALVES FOR AIR OR OTHER GAS COMPRESSION 0R VACUUM PUMPS Filed May 20, 1.952 5 Sheets-Sheet l Nov. 1, 1955 G. B. BOYCE 2,

INLET CONTROL VALVES FOR AIR OR OTHER GAS COMPRESSION OR VACUUM PUMPS Filed May 20, 1952 5 Sheets-Sheet 2 Z ran/6m 5 Sheets-Sheet 3 G. B. BOYCE INLET CONTROL VALVES FOR AIR OR OTHER GAS COMPRESSION OR VACUUM PUMPS Nov. 1, 1955 Filed May 20, 1952 f /f/f// 5%uuuur G. B. BOYCE OL VAL RESSION Nov. 1, 1955 V FOR AIR OR OTHER VACUUM PUMPS INLET CONTR GAS COMP 5 Sheets-Sheet 4 Filed May 20, 1952 zwwwm meat-01 G. 5. 1505 06 Nov. 1, 1955 G. B. BOYCE 2,722,395

INLET CONTROL VALVES FOR AIR OR OTHER GAS COMPRESSION OR VACUUM PUMPS 5 Sheets-Sheet 5 Filed May 20, 1952 United States Patent INLET CONTROL VALVES FOR AIR OR OTHER GAS COMPRESSION 'OR VACUUM PUMPS Guy Baron Boyce, St. Johns Hill, Shenstone, England, as-

signor to Alfred Bullows & Sons Limited, Walsall, England Application May 20, 1952, Serial No. 288,852

Claims priority, application Great Britain May 28, 1951 4 Claims. (Cl. 251-28) This invention relates to air or other gas compression or vacuum pumps, and particularly (though not eX- clusively) to pumps of the kind comprising a rotor mounted eccentrically in a cylindrical working chamber and provided with slidable radial blades.

The object of the invention is to provide a valve for controlling automatically the inlet to the pump in response to variations of pressure in the associated distributing system.

The invention comprises the combination of a springloaded gas-inflow controlling member operable by pressure of a liquid, and a spring-loaded liquid-controlling valve also operable by pressure of the liquid.

In the accompanying drawings:

Figure 1 is a sectional view illustrating one embodiment of the invention, Figure 2 being a fragmentary view illustrating one of the normal working positions of the liquid controlling valve.

Figures 2a and 2b are respectively a sectional side view and a sectional end view illustrating the invention applied to an air pump of the kind specified, Figure 2a being taken on the line BB of Figure 2b, and Figure 2b being taken on the line AA of Figure 2a.

Figures 3, 3a and 3b are respectively similar views to Figure 1, 2a and 2b illustrating a second embodiment of the invention, Figure 301 being a section of the line D--D of Figure 3b, and Figure 3!) being a section on the line CC of Figure 3a.

Figures 4, 4a and 4b are respectively similar views to Figures 1, 2a and 2b illustrating a third embodiment of the invention, Figure 4a being a section on the line EE of Figure 4b, and Figure 4b being a section on the line F--F of Figure 4a.

In the application of the invention as shown in Figures l and 2, to a valving means for controlling the rate of inflow of air or other gas to an air or other gas compression pump, there is provided in a part a through which the gas must flow before entering the pump inlet, a ported cylindrical chamber b. In this chamber is contained a ported and hollow piston valve of stepped form, the valve being loaded at one end by a spring d which tends to move the valve to its fully open position. In this valve (herein referred to as the inflow-controlling valve) is contained a valve e which serves to close the inlet k when the pump is at rest. In the form shown, the valve e is .of the poppet type and is arranged to cooperate with an annular seating f in the valve 0. The valve e is held on its seating by a spring g and is movable away from the seating by the suction action of the pump.

In another cylindrical chamber h is arranged a piston valve i loaded by a spring and operable by pressure of a motive liquid, this valve being adapted to control the flow of the liquid to the inflow controlling valve 0.

When the pump is of the kind in which oil under the pressure of the system supplied by the pump is used for sealing the working parts of the compressor, this oil is used for actuating the inflow-controlling valve 0 and the 2,722,395 "Pa-tented Nov. 1, 1 955 ice liquid-controlling valve i. Otherwise motive liquid is supplied from any other convenient source under -a pressure related to the pressure in the compressed gas system.

The air or other gas admitted at k is supplied to the compressor through-the passage m. The liquid is admitted at n. The valve 0 controls the passage m, and the valve i controls a passage 0 through which the'liquid can pass to the pump. The valve i also controls a passage p leading to the stepped part of the valve 0.

The mode of action is as follows:

When the compressor is at rest, or the pressure -in the associated system is low, the liquid-controlling valve i occupies the position shown in Figure l, in which it allows the inflow-controlling valve c to be moved by its spring 42' to the position in which maximum inflow of gas can enter the pump through the 'valve e. With increasing gas pressure in the system it is required to reduce the rate of gas inflow to the pump. Such increase is also accompanied by increase of the liquid-pressure, and this latter causes the liquid-controlling valve 1 to move against the action of its associated spring to the position shown in Figure 2, so as to admit liquid to the stepped part of the inflow-controlling valve 0, thus causing the latter to move against its associated spring in the direction for reducing the effective area of the ports leading to the passage in and thence to the pump inlet. With subsequent fall of pressure in the system the spring j of the liquid-controlling valve 1' returns to the position shown in Figure 1, and thereby allows the inflow-control-ling valve to be moved by its spring d to its previous position, the liquid previously acting on this valve being displaced thereby and discharged to the pump inlet through the passage 0. From the foregoing it will be understood that the inflow-controlling valve 0 can occupy any position between the fully-open and fully-closed positions, its position being automatically controlled by the liquid pressure acting on the liquid-controlling valve i, this pressure being related to the pressure in the system supplied by the pump.

One mode of applying the embodiment of the invention above described to an air pump of the kind specified is illustrated in Figures 2a and 2b in which the pump comprises a rotor 10 provided with slidable vanes 11, and a stator 12 formed with a cylindrical chamber 13 in which the rotor is eccentrically mounted. The air admission and delivery passages of the pump are indicated respectively by 14 and 15. The pump is mounted in a casing 16 into which the .air from the pump delivery passage 14 is discharged, and which also serves as an oil resenvoir, the oil level being indicated by 17. Consequently, the oil is subjected to the pressure of the air discharged by the pump, and as the oil has constant access to the valve i through the port n, it follows that this valve is movable against its spring loading by the oil pressure. It will be understood that the air admission passage 14 is in constant communication with the valve e through the passage k (Figure 2b).

In the arrangement shown in Figure 3, the body part a is provided with an air inlet k, and an adjacent passage m leading to the inlet of the compressor. The valve e has formed on it a stem r Which is freely slidable in an axial bore in a valve-controlling member s which is loaded by a spring 1, the said member s being slidable in a bore in the body part. The member s is operable in one direction by liquid pressure under the control of the liquidoperated valve i which is loaded by the spring j. The valve i controls the flow of liquid entering through the port n and passing therefrom along a port p to the region it in the bore containing the member s, this region being flanked at one side by a stationary Wall v and at the other side by a head w on the said member. When the valve i is in the position shown in the drawing liquid can return from the port p to the compressor through the port 0, the latter being connected in any convenient manner (not shown) to the passage m leading to the compressor inlet.

Assuming the compressor to be at rest, the valve e can move freely on to a seating around the air entrance k and so close the entrance under the action of the pressure that may then still exist in the compressor. When the compressor is set in motion the suction thereby set up at 111 causes the valve e to open and so admit air to the compressor. So long as the pressure of the liquid entering at n is below a predetermined amount, the valve i remains in the position shown, and the valve e can open to its full extent. But when the liquid pressure exceeds that amount, it moves the valve i against the action of the spring sufiiciently to open the port p. The liquid can then act on the head w of the member s and move it to the right, thereby causing it by its action on the shoulder at of the stem r of the valve e, to move this valve in the direction for restricting the air inflow k. As in the example first described, the amount of opening of the valve e depends on the pressure of the liquid entering the port p under the control of the valve i.

To minimize risk of hunting of the valve i it is desirable to maintain a constant fluid pressure in the region at the left hand end of the valve. To achieve this condition it is convenient to maintain the said region at atmospheric pressure while the compressor is in action. The said region is therefore put into communication with the left hand end of the bore containing the valve s by way of a port 2, and in the stem r of the air valve k is formed an axial bore which is controlled by a non-return valve 4. When the compressor is in action the air in the said region at the left-hand end of the valve i is thus kept at atmospheric pressure. When the compressor is at rest and the associated system is under pressure, loss of this pressure by leakage past the valve i and through the port 2 and bore 3 is prevented by the valve 4.

in Figures 3a and 3b, which illustrate diagrammatically the example shown in Figure 3 applied to an air pump of the kind specified, the pump comprises a rotor 10 provided with slidable vanes 11, and a stator 12 formed with a cylindrical chamber 13 in which the rotor is eccentrically mounted, the air admission passage of the pump being indicated by 14 (Figure 3a). The pump is mounted in a casing 16 into which the air from the pump delivery passage (not shown) is discharged, and which serves as an oil reservoir as previously described, so that the oil is subject to the pressure of the air discharged by the pump. As the oil under pressure has constant access to the valve i through the port n as shown in Figure 3, this valve is movable against its spring loading by the oil pressure.

In the arrangement shown in Figure 4, the air inlet is indicated by k, and air can pass from this inlet through a passage y to the port In which is in communication with the compressor inlet. The port y is controlled by the liquid operated valve which is loaded by a spring d. This valve is in the form of a stepped piston contained in a cylindrical bore in the body part a, which bore is supplied with liquid through a port p under the control of the valve i, this valve being loaded by a spring j, and the region containing the spring being open to the region adjacent to the entrance to the port y by way of a port z. The valve i not only controls the flow of liquid from the entrance port 11 to the port p, but also the discharge of liquid through the port p to the compressor by way of the port 0.

When the compressor is at rest the air inlet k is closed by a valve e under the action of residual pressure in the compressor. When the compressor is in action at a low rate, the suction in the port m opens the valve e and air is then admitted at the full rate to the compressor. Meanwhile the valve i occupies the position shown. When the liquid pressure exceeds a predetermined amount, it moves the valve i in the direction for opening the port p, thereby causing the valve 0 to move against the spring d for restricting the air entering the port y. With fall of liquid pressure the valve returns towards the position shown and liquid can then pass from the port p to the port 0. As in the previous examples, the extent to which the valve 0 restricts the air inflow depends on the extent to which the port 2 is opened by the valve i.

In Figures 4a and 4b, which illustrate diagrammatically the example shown in Figure 4 applied to an air pump of the kind specified, the pump comprises a vane-carrying rotor 10 mounted as previously described in a cylindrical chamber 13 to which air is admissible under the control of the valve c. The pump is mounted in a casing 16 into which air from the pump delivery passage (not shown) is discharged and which serves as an oil reservoir, so that the oil is subject to the pressure discharged by the pump, the oil having constant access through the port n to the valve i for the purpose indicated.

By this invention the output of the compressor is automatically correlated with the demand on the associated system in a very simple manner.

Whilst in the foregoing the invention has been described with reference to compressors, it is also applicable in essentially the same manner to vacuum pumps.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. Means for controlling the inflow of fluid to an air or other gas or vacuum pump, comprising in combination a gas inlet, a liquid inlet, a gasand liquid-outlet, a spring-loaded member for controlling gas flow from said gas inlet to said outlet, actuating means through the medium of which said member is operable by liquid pressure, a first passageway for conducting liquid under pressure from said liquid inlet to said actuating means, a spring-loaded valve operable by liquid under pressure from said liquid inlet, and arranged to control the flow of liquid under pressure from said liquid inlet to said first passageway, and a second passageway for conducting liquid from said first passageway to said gasand liquidoutlet when communication between said liquid inlet and said first passageway is interrupted by said valve.

2. Means as claimed in claim 1 and having a suctionoperable valve for controlling gas flow through said gas inlet.

3. Means as claimed in claim 1, in which said valve is of the piston type, and co-operates at one end with said liquid inlet, means being provided for maintaining a substantially constant fluid pressure at the opposite end of said valve.

4. Means as claimed in claim 1, in which said actuating means is formed by a shoulder on said spring-loaded member.

References Cited in the file of this patent UNITED STATES PATENTS 1,743,055 Walker Jan. 7, 1930 1,948,907 Egli Feb. 27, 1934 2,070,662 Johnson Feb. 16, 1937 2,173,819 Boldt Sept. 26, 1939 2,584,638 Staude Feb. 5, 1952

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