US2118843A - Gas compressor and clearance varying means therefor - Google Patents

Description

H. C. GUILD GAS COMPRESSOR AND CLEARANCE VARYING MEANS THEREFOR Filed Dec. 16, .1936

INVENTOR HEAD Patented May 31, 1938 Parent oFFleE GAS COIHPRESSOR AND CLEARANCE VARY- ING S THEREFOR Herbert 0. Guild, New York, N. Y.

Application December 16, 1936, Serial No. 116,143

8 Claims.

My present invention relates to devices for varying the volume of the clearance space in a gas compressor, particularly for the purpose of varying the capacity of the compressor, that is, varying the amount (weight) of the compressed gas that a given compressor will deliver, other capacity varying factors remaining the same.

As applied to the case of a compressor of the ordinary cylinder and piston type, it may be explained that, other things being equal, the maximum compression actually attained, depends upon the point in the rearward movements of the piston at which the inlet valve opens, and

upon the point in its forward movement at which the outlet valve opens.

Usually, both the inlet and outlet valves are check valves which automatically open and close according as the reciprocating piston raises or lowers the internal pressure above or below the external pressures on the valves. Consequently, the normal clearance is usually made as small as is mechanically practical.

My invention assumes a normal condition, including predetermined piston speeds; and any of the permissible external inlet and outlet pressures, and any displacement-clearance ratio that will give internal pressures sufficiently in excess of the external pressures on the outlet. For any such normal condition, increasing clearance space increases the volume of gas that remainscome pressed in the cylinder when the outletvalve closes. This increases the distance the piston must travel rearward during the suction stroke before said gas can re-expand to pressure low enough to cause opening of the inlet valve. This decreases the amount (weight) of new gas which can be taken in. In short, other things being equal, increasing clearance space increases the amount of idly compressed and re-expanded gas in the cylinder, thereby decreasing the intake and output capacity of the compressor.

While there are other more complicated ways of varying the amount of the idly re-expanding gas, the only simple way, so far as I am aware, has been by adding a definite fixed volume of clearance space, in the form of one or more separate blind pockets, known as clearance control pockets. As such a pocket must communicate with the clearance space, a common way of adding it to a compressor supplied through two or more intake check valves, is to substitute the pocket for one of said valves.

' One object of my invention is to avoid'necessity for such substitutions; and to operatively combine a gas-tight clearance pocket with at least one of the inlet valve elements, so that a valve passage normally used for the unidirectional supply of gas to the cylinder, may be cut off from the supply and utilized for the idle to and fro flow into and out of said pocket. I accomplish this by simple mechanism whereby the valve may be held open and a gas-tight chamber formed in operative relation for in and out flow of the addi-- tional compressing and expanding gas, through the thus opened valve passage.

While this broad principle may be applied to any compressor having two or more inlet valve elements, the necessary mechanism is simpler, cheaper and more efficient when applied to check valves, particularly annular plate valves such as are commonly employed in this art. In such case simple well known mechanism, including fingers extending through the passage or passages for inlet of gas to the valve plates, may be employed for holding the valve plates open; and the valve opening mechanism may be operated interdependently with pocket closing elements.

In so much as the inlet valve cannot be functioning as such, when the blind pocket is functioning, it will be obvious that the invention is particularly useful where two or more separate valves or valve elements are employed. In fact, one of its most practically useful applications is in connection with compressors wherein as many valves are employed as can be arranged around the clearance space of the cylinder. Commonly, three, four or more intake valves or valve elements are employed for the intake, and a similar number for the outlet.

The above and other features of my invention may be more readily understood from the following description in connection with the accompanying drawing, in which Fig. 1 is a more or less conventional or diagrammatic View showing a compressor in transverse section, taken approximately in the plane of the clearance space, and showing manifold passages with a multiplicity of intake and outlet valves;

Figs. 2 and 3 are detail sections on line 2-2, Fig. 1, showing an intake valve provided with valve-opening and pocket-forming elements, in accordance with my present invention; Fig. 2 showing the position of the parts when the intake valves are functioning, and Fig. 3 the position when the valve plates are held inoperative and a blind pocket space has been closed in above them.

Figs. 4 and 5 show modifications.

In Fig. 1, the clearance space is surrounded by cylinder wall A, in which are openings controlled by four ordinary annular plate inlet valve assemblies B, B, two of which are shown as equipped with my pocket forming elements C, C. The outlet valve assemblies D, D, are like B, B, except that the valves open outwardly instead of in- Wardly.

The cylinder A carries an outer casing E closing in an annular space separated into an intake manifold F and an outlet manifold G, by the partitions H, H.

As shown, the valve assemblies are insertable through manholes in the outer casing E, which are closed by gas-tight cover plates J through which extend screw thrust members K, K, whereby the valve assemblies are clamped gas-tight in the openings of cylinder A.

In Fig. 2, the valve assembly B is conventionally indicated as including the usual upper disc I, adapted to be clamped gas-tight in the opening through the wall of cylinder A; and a lower disc 2 secured to the upper disc by a screw. Intake of gas is through passages 3, 3, in the uper disc, and passages 3a, 3a, in the lower disc. The lower surface of the upper disc forms seats for the ring plate valves 4, each of which is normally held against its seat by springs 5. These springs are only strong enough to ensure seating of the valve against a slight pressure differential. Consequently, as soon as the piston head is retracted far enough to reduce the internal pressure below the gas pressure in the supply manifold minus the spring pressure, the supply pressure forces the valve plates downward and they remain open until the piston moves forward again, and compresses the gas enough to make the internal pressure plus spring pressure exceed the supply pressure; whereupon the combined upward pressures close the valve.

In the ordinary case, this valve assembly is held down by the thrust of a screw K, as described in connection with Fig. 1. In the present case, however, the valve assembly is utilized as the bottom of the clearance pocket and is held down by tubular member 6, which afiords side walls for said pocket; and is forced into air-tight engagement with the upper surface of said assembly by screws K, K.

The upper part of tubular member 6 is ventilated for free inlet of gas, while the lower portion affords imperforate side walls of the pocket. The side wall portion of the pocket space is formed with a valve-like seat 1, adapted to be closed gastight by plate 8, an edge portion of which accurately fits the seat I. This cover plate 8 may be raised or lowered by any suitable means, such as screw K.

The means for holding open the valves when this pocket space is closed, is shown as including fingers III, which are carried by plate 8, and which extend through the ordinary gas inlets. These fingers III are of proper length to hold open the ring valve plates 4, when the fingers are moved downward the distance required to seat the plate 8 and form the closed pocket, as shown in Fig. 3.

Figs. 4 and 5 show modifications, the most important of which is utilizing an adjustable piston in place of cover plate 8 and making the fingers in telescoping sections instead of the integral fingers I0. Another optional modification is making the member 6 that forms the side walls of the compression space, integral with the top plate I of the valve assembly.

So far as the parts are the same, the reference numerals are the same, and where they are similar the same numerals with an exponent are used as far as possible.

In Fig. 4, the plate I a is integral with the cylinder member 60. so that the compression chamber is an integral cup, and it is closed in and opened by the adjustable piston 8a, which is like cover plate 8, and is vertically adjustable by any suitable means, which may be a swivelled screw like K, Fig. 2.

The valve opening finger is in two telescoping sections including the finger proper Illa and the tube II with which it telescopes. The tube is provided with a slot I2, in which slides the stop pin I3 carried by Illa; and in the upper end of tube II is the spring I4 which is powerful enough to open the valve whenever Fig. 10a. contacts therewith.

In the position shown in the drawing, the piston 8a. is at the lower limit of its movement, and the pin I3 is at the upper end of slot I2. When the piston is withdrawn the spring continues to push the finger and hold the valve 4 open until the piston reaches a suflicient height so that the pin I3 comes in contact with the bottom of slot I2, whereupon the valve closes.

In Fig. 5, the construction and operation is similar except the entire tube I I0 with its slot I2 is located entirely above the piston and the slot is closed in gas-tight, by sleeve I5, which is brazed or welded to tube H0, at the top and bottom of the slot. This gives a much longer rangeof piston movement and the cylindrical part of the cup may be'much higher, giving greater maximum volume for the clearance pocket.

While I have shown and described in detail a simple and novel construction for closing a pocket, opening the valve and utilizing the Valve passages as means for increasing the volume of the clearance space, as applied to a common type of compressor and valve, it will be obvious that many variations are possible, as for instance, means for rendering the movable valve elements inoperative, need not be fingers, and need not be carried by or even interdependent with the operation of the means for closing in the pocket space. Also the means for closing the pocket space need not be a cover plate, provided the pocket forming elements comprise at least two relatively movable members that are capable of adjustment for closing a pocket and cutting off the gas supply in one position; and for leaving a free gas supply inlet, in another position. Also the principle may be useful Where the movable valve elements are not plate valves and are not even check valves. Also the volume of the pocket may be varied to suit the compressor. Also while I have shown a valve assembly in which there are two separate ring plate valve elements, this is not essential, and where there are two valve elements as shown, only one of them need be opened and its passages closed in by a pocket.

As before indicated, it is not necessary or desirable to equip all of the intake valves with the pocket forming mechanism because pocketing all of them would cut oif the gas supply completely. In Fig. 1, where there are four intake valves, only two of them are shown as equipped with pockets; but obviously the volume of clearance space may be more widely varied by having three valves so equipped; and one only may be sufficient for certain purposes. The pockets need not all be of the same volume or of the same mechanical construction.

I claim:

1. A gas compressor having a gas intake manifold formed with several intake openings communicating with a clearance space in the cylinder, corresponding exterior openings with 010- sures therefor, and check valve assemblies insertable and removable through said exterior openings and each adapted to be fitted gas-tight in one of said openings into the clearance space, each assembly including a plurality of inwardly opening ring plate check valves; and, in combination with said parts, means for holding open one or more of said valve plates, and closing in a clearance pocket in reciprocal fiow relation to said valve; said means including a tubular pocket-forming member in said manifold having one end adapted to fit gas-tight against the intake face of the valve assembly, screw means carried by the external closure and applying downward thrust upon said tubular member to force the valve assembly into gas-tight fit with its opening into the clearance space; a closure member for said tubular member and externally operable screw means for adjusting it in gas tight engagement with said tubular member to form a gas-tight pocket; and for retracting it; and fingers carried by said pocket closing member, extending through the gas inlets of said valve assembly and of proper length for engaging and holding open the ring plate valves when said closure is in gas-tight engagement with said tubular pocket forming member.

2. A gas compressor having a gas intake manifold and at least two separate openings therefrom into a clearance space of the compression cylinder, removable check valve assemblies each adapted to be fitted gas-tight in one of said openings, each assembly having at least one inlet passage controlled by an inlet check valve element, and at least one of said valved passages of one of said assemblies being maintained continuously operative for intake supply of gas to said space; and, in combination with said parts, means for holding open the check valve element of at least one other of said inlet passages to permit alternating fiow of gas to and from the clearance space through the thus opened passage; a hollow member within the intake manifold, adapted to form side walls of a clearance pocket communicating through said open passage with the interior of the compression cylinder; means for applying inward thrust to said hollow member to force it against the assembly containing said open passage, and thereby force said assembly into gas-tight fit in its opening; and means for completing the clearance pocket, including means for closing said hollow member gas-tight, completely cutting off the open passage from gas in the supply manifold and ailording a gas-tight space confining said alternating fiow of gas, thereby aifording additional fixed-volume clearance space for the compressor.

3. A gas compressor having a cylinder clearance space supplied with gas from the source through at least two independent passages each controlled by a separate inlet check valve element; at least one of said valve elements being maintained continuously operative for intake supply of gas to said space; and, in combination with said parts, means for holding open at least one other of said valve elements to permit alternating flow to and from the clearance space through the thus opened passage; and means for forming a gas-tight chamber, completely cutting oif supply of gas from the source and atfording an added volume gas-tight space confining said alternating fiow of gas, thereby affording additional clearance space for the compressor.

l. A gas compressor having at least two intake openings communicating with a clearance space in the cylinder, check valve assemblies) each adapted to be fitted gas-tight in one of said openings, each assembly including at least one inwardly opening check valve; and, in combination with said parts, means for holding open a valve of one or more of said assemblies and closing in a clearance pocket in reciprocal fiow relation thereto; said means including a tubular pocket-forming member having one end adapted to fit gas-tight against the intake face of the valve assembly, screw means for applying downward thrust upon said tubular member to force the valve assembly into gas-tight fit with its opening into the clearance space; a closure memher and externally operable screw means for adjusting it in gas-tight engagement with said tubular member to form a gas-tight pocket; and for retracting it; and fingers carried by said pocket closing member, extending through the air inlets of said valve assembly and of proper length for engaging and-holding open the valves when said closure is in gas-tight engagement with said tubular pocket forming member.

5. A gas compressor having at least two intake openings communicating with a clearance space in the cylinder, check valve assemblies each adapted to be fitted gas-tight in one of said openings, each assembly including at least one 'in a clearance pocket in reciprocal flow relation thereto; said means including a tubular pocket forming member having its outlet end integral with the intake face of the valve assembly, screw means for applying downward thrust upon said tubular member to force the valve assembly into gas-tight fit with its opening into the clearance space; a closure member and externally operable screw means for adjusting it in gas-tight engagement with said tubular member to form a gastight pocket; and for retracting it; and fingers carried by said pocket closing member, extending through the air inlets of said valve assembly and of proper length for engaging and holding open the valves when said closure is in gas-tight engagement with said tubular pocket forming member.

6. The combination specified in claim 5', with the further features that the closure member for the pocket is a piston slidable in said tubular member and the fingers for holding open the valves are endwise slidable and spring pressed to hold the valve open in any of the positions to which the piston is adjustable.

7. The combination specified in claim 3, with the further feature that the means for forming the gas-tight chamber includes a cylinder and a piston adjustable therein; and the means for holding open the valve elements includes valve opening elements operable to hold the valve elements open when the piston is in any of the desired pocket-closing positions.

8. The combination specified in claim 3, with the further feature that the means for forming the gas-tight chamber includes a cylinder and a piston adjustable therein; and the means for holding open the valve elements includes fingers that are endwise slidable and are spring pressed to hold the valve elements open when the piston is in any of the desired pocket-closing positions.

HERBERT C. GUILD.

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