US2341709A - Valve - Google Patents

Description

Feb. 15', 1944. M. v. FRIEDELL VALVE Filed May 20, 1943 l/ genre/44914;@ JAP WMM v .4 Y,

Patented Feb. 15, 1944 UNITED STATES PATENT OFFICE VALVE Morley V. Fr'iedell, El Cerrito, Calif.

ApplicationMay 20, 1943, Serial No. 437,785 v 2 Claims.

This invention, a highly efficient, noiseless valve, is designed to overcome many of the deciencies and faults of conventional types of valves, particularly those used in connection with gas transfer devices, such as compressors and vacuum pumps, and particularly such as operate under impulse, including reciprocating and oscillating compressors, pumps, and blowers.r

Air compressors and vacuum pumps, and gas compressors for refrigerating systems usually require a comparatively slight valve opening or lift when operating under normal intake and back pressures or when operating under normal intake pressure against an existent high pressure, but require a considerably greater opening or lift when the intake pressure is above normal or the back pressure is below normal.

For instance: In refrigerating systems the'liquid gradually expands to its gaseous form with direct access to the intake of the compressor, creating a positive pressure at the intake. Under normal conditions the compressor recompresses the gas before there is any appreciable build-up of the positive pressure, and While the back pressure from the previously compressed and liquied gas is substantially normal. This is the condition which requires the minimum lift of the valve.

When the compressor is started for'the first time in a new unit, or after the system has been defrosted, this positive pressure at the intake may readily reach a value of four or ve times normal while the back pressure may be reduced.

Obviously, with this high intake pressure, the volume of free gas available per cycle of the compressor may be anywhere up to five or more times normal, and since the compressor will be operating against a normal to W back pressure, the valve will be the sole restriction against delivery of the gas from the compressor. Under such conditions, with a valve lift adjusted for normal intake and normal back pressures, the internal back pressure of the compressor will be extremely high, causing heating of the compressor and consequent delivery of the compressed gas at a comparatively high temperature, with resultant increased power demand and possible detrimental effects on both, the compressor and its prime mover, and, decreased eliciency throughout the entire system.

If suflcient valve opening or lift is provided to compensate for all conditions of operation (and which is the conventional procedure), the einciency of the compressor and the entire system will be impaired and valve noise will lie-considerably increased-conditions which are r`by no means desirable.

Furthermore, when air or gas is being pumped against a high back pressure requiring only a slight valve lift,the requirement-,may be suddenly and greatly increased if either oil or Water must pass through the valve opening along with the gas. If the opening is insucient, knocking. or hammering is certain to occur, and the compressor or pump might be damaged or even wrecked by the impact. For this-reason it is cusi tomary to allow a considerably greater valve lift than is normally required, and this increased valve lift results in valve clatter with consequent rapid deterioration of the valve and its seat.

This invention provides a valve which operates automatically to restrict the valve for normal conditions and to compensate for variations in intake pressure, back pressure, and for any oil or water slugs which may form -for delivery along with the air or gas. The valve is noiseless in operation, seats perfectly Without requiring axial alignment of the valve and its seat whenA using the spherical type of valve, though the same principle may be applied tothe conventional mushroom type or the disc type valve. However, the spherical type of valve is preferred because of its seating eiciency and longer life.

The objects and advantages of the invention are as follows:

First, to provide a noiseless valve for air and gas compressors and pumps, and other related devices.

Second, to provide a valve which will automatically compensate for variations in pressures and volumes of gases at intake and delivery, as also for the existent back pressure, and for liquids which might be included in the delivery with the gas, such as oil or water.

Third, to provide a valve as outlined preferably of the spherical-type which will seat perfectly even when the valve is not axially aligned with its seat.

Fourth, to provide a valve'as outlined which under normal operating conditions will provide the minimum necessary opening for ecient discharge coupled with rapid closure when the gas has been discharged, and which will automatically increase the opening .for passage of the gas under conditions of high intake pressure or low external back pressure and to pass any liquids which might be incorporated with the gas being delivered through the valve opening.

Other objects and advantages of the invention W-ill become apparent as the following description is read on the accompanying drawing, in which:

Fig. 1 is a top plan view of the invention.

Fig. 2 is a vertical section through the invention.

Fig. 3 is a section taken on line 3--3 of Fig. 2.

Fig. 4 is a section taken on line 4--4 of Fig. 2.

Fig. 5 is a fragmentary sectional elevation showing a conventional mushroom type valve substituted for the preferred spherical type.

Fig. 6- is a fragmentary sectional elevation showing another modication employing the conventional disc type valve.

The invention comprises a valve casing including a cap member Ill and a base member II and the assembly of operable and adjustable elements incorporated therein.

The cap member is cylindrical and provided With external threads at one end I2 and with the other end I3 reduced in diameter to flt respectively in a threaded bore I4 and the smaller cylindrical extension I5 formed in the pump or compressor structure I6. This cap member has a head I1 provided with a circular series of combinedair passages and spanner wrench sockets I8 and an axial threaded bore I9.

The base member I I is also cylindrical with a diameter preferably equal to that of the reduced portion of the cap member and has a bore 20 terminating in a valveyseat 2|, providing a. replaceable valve seat which can be easily removed and replaced in case of'wear or damage.

The valve adjusting stem 22 is threaded as shown and provided with adjusting and locking means, such as the screwdriver slot 23 and lock nut 24, and terminates at its lower end inl a collar 25, and anaxial bore 26 to function as a spring socket is formed in the lower end.

Slidably mountedvon the valve adjusting stem 22 is a valve stop l21 which has a counterbore 28 slidably fitting the collar 25 and seating on the top face thereof, and having a base 29 with a diameter substantially equal to the diameter of the valve, with grooves 30 formed radially to break suction and adhesion between the valve and the'base 29, though serrations or passages could be substituted for these grooves.

The upper end of this stop is considerably reduced in diameter and terminates at its lower end in a spring seat 3|. A spring thrust collar 32 is threadedly mounted on the valve adjusting stem as shown and is relatively adjustable for controlling the urgence of the compression spring 33 and to limit the maximum lift of the valve, and a suitable locknut 3ft is provided for locking the collar 32 in its adjusted position.

The Valve 35 is spherical and seats on the valve seat 2l in any relative position, is internally hollowed for lightness, and has a spring pilot 36 on which the spring 31 is resiliently secured and which spring is housed in the spring pocket 26 in the valve adjusting stem 22 and seats against the bottom 33 of this pocket or bore.

The spring pilot 36 and the spring 31 are both appreciably smaller in diameter than the bore 26, which allows the valve to find a perfect seat Without frictional or axial restrictions. The spring 31 has `comparatively light tension, just enough t0 urge rapid seating of the valve without creating unnecessary back pressure. To create rapid seating with minimum back pressure, the valve is internally hollowed to make it as light as possible, and the normal lift of the valve indicated at 39 is iixed at an absolute minimum for the normal volume of gas to be passed against a normal back pressure. This lift, governed by the volume of gas to be discharged with each impulse, the pressure against which the gas is normally discharged, and the size of the valve, may be as little as .002 inch, and it seldom happens that a lift in excess of .015 inch is necessary, for which reason the spring 31 can be comparatively light or of 10W tension, and due to this minimum lift and the light tension spring, the valve is practically noiseless in operation.

The valve lift is adjusted by means of the valve adjusting stem 22 for the specific conditions under which the gas is delivered. The lift is a minimum when the gas is discharged against a Vcomparatively high back pressure in conjunction with a comparatively low intake pressure.

With the valve lift adjusted for normal operation, other conditions must be compensated for, such as when operation of a compressor or pump is started when the discharge is against some low pressure ranging upward from atmospheric, or when the intake pressure is above normal or positive, and, when water of condensation, or oil used for lubrication or for sealing is deliveredV with the gas through the discharge, in either of which cases a greater lift must be provided to compensate for the increased Volume, and this compensation is made through the stop member 29 and spring 33.

The spring 33 is of somewhat greater tension than the spring 31, with just sufficient excess tension to resiliently retain the stop member against lifting except when additional valve lift as previously pointed out, is required. The spring thrust collar 32, being adjustable on the adjusting stem, can be adjusted to limit the lift of the stop member to any desired maximum required to compensate for any abnormal conditions. This resiliently held stop member is in the main responsible for the quiet operation of the valve, because the valve, when lifting, does not impact against a rigid, immovable stop, but against a resiliently held stop which gives under impact and thereby absorbs any resultant shock, and to the cushioning effect of the oil between the contacting surfaces of valve and stop, and the absorption of the valves inertia by the spring 33. It permits of a greater valve lift with noiseless operation.

The operation of the valve is as follows: When operating normally, the compressor or pump will discharge against some predetermined pressure, herein referred to as back pressure. The valve is adjusted for that specific back pressure, and the valve under such conditions lifts to contact the stop member against the urgence of the spring 31 when the gas is being delivered through the Valve passage against that predetermined pressure. If there is a sudden lift of the valve, it will react on the stop member lifting it slightly to absorb the shock, coupled with immediate rebound. If a slug of oil or other liquid is discharged along with the gas, more space will be required between the valve and its seat to pass the liquid, lifting the stop member against the urgence of the heavier spring 33 to whatever extent is necessary to pass the liquid, up to the limit deiined by the thrust collar 32.

The same applies when the compressor is started against a pressure appreciably below normal when the volume of the discharging gas is greater, or when the intake pressure is above normal as in the case of refrigeration following defrosting which results in a greater intake volume in terms of free gas. Thus the valve operates at highest efficiency for normal operating conditions andl compensates for any variations in back pressure, intake pressure, thermal variations, and vapors or liquids to be passed along with the gas.

The modication illustrated in Fig. is similar in all respects to the preferred form in Figs. 1 to 4 with the exception that a mushroom type of valve is substituted for the spherical type, and this mushroom type of valve must seat accurately and axially if a perfect seal is to result, therefore the valve must have an `axial stem 40 which is slidable in the axial bore 2t'.

The modication illustrated in Fig. 6 is also similar in all respects with the exception that the disc type of valve is shown, and for this type of valve it is necessary to project the stop member 29 below the bottom of the collar 25 as indicated at 4|, and a flat seat |32 is required for proper seating of the disc 43. l

It Will be understood that variations in construction and arrangement of parts, which Variations are consistent with the appended claims, may be resorted to Without detracting from the spirit or scope of the invention, or sacrificing any of the advantages thereof.

I claim:

l. A Valve comprising; a cap member having a head provided with an axial threaded passage and with air passages; a base member having a central passage and a valve seat; a valve seated on said seat and a compression spring attached at one end centrally of said valve and functioning as a valve stem and as resilient urging means to seat said valve; an adjustable member adjustable in said threaded passage and havingr at one end a bore for freely supporting said spring and terminating in a seat for the other end'of said spring, and a collar formed at said one end of the adjustable member; a stop member slidably mounted on said adjustable member and cooperating with said collar to limit the movement of said stop member toward said valve, and a second compression spring urging said stop member against said collar and a seat adjustable on said adjustable member for said second spring, whereby said valve may increase its normal lift under other than normal operating conditions by overcoming the urgence of said second spring and lifting said stop member.

2. A valve cap having an axial threaded passage and an adjusting member mounted in said passage having adjusting means at one end and a collar and an axial spring socket formed at the end; a spherical valve and a seat therefor; a compression spring attached centrally of said valve and housed in said socket and functioning as a valve stem and as valve urging means; a stop member slidable on said adjusting member and seating on said collar; a spring seat member adjustable on said adjusting member and a second -compression spring cooperating between said spring seat member and said stop member.

MORLEY V. FRIEDELL.

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