US2191908A - Compressor unloader - Google Patents

Description

Feb. 27,11940.

S. F. EVELYN COMPRESSOR UNLOADER Filed 'March 11, 1938 Steven E' Evelyn INVENTOR BYv . ATTORNEY Patented Pena-1,1940,

PATET., OFFICE 2,191,908 oonrnnssoa uNLoADEn Steven F. Evelyn, Holyoke, Worthington Pump and tion, Harrison, N. J.,

luana., assigner to I Machinery Corporaa corporation of Dela- APPlieltion March 1l, 1938. Serialv No. 195,251

1 Claim.

This invention relates to unloaders for compressors and a general object of the present invention is to provide a simple, practical, and positive loading and unloading mechanism for air or gas compressors, which will be positive in action and will unload the compressor upon the cutting oil? of operating power thereto and will load the compressor upon the cutting in of operating power.

An object of the present invention is to provide in an unloader mechanism for compressors thervmal time delay means which will provideV a time interval between the starting of the compressor and itsloading, thereby allowing the compressor l5 and its operating motor to reach full speed before the load torque is imposed.

With these and other objects in view, as may appear from the accompanying specication. the

invention consists of various features oi construction and combination of parts,which will be rst described in connection with the accompanying drawing, showing a compressor unloader embodying the invention, and the features forming the Y invention will be speciiically pointed out in the claims.

In the drawing:

Figure 1 is a diagrammatic view showing the Aimproved unloading and loading mechanism in diagram and showing a part of the compressor in section. A Y

'Figure 2 is a longitudinal section through the valve which controls the loading and unloading ofthe compressor and is taken at right angles to the line 2-2 of Figure 1.*

Referring more particularly to the drawing the improved unloading mechanism is shown as used in connection with a single cylinder compressor 1I which is unloaded by the holding open of the suction valve 2 by the pressure operated mecha- 'nism 3, all of which is standardconstruction in present day commercial use. However it is to be understood that the unloading mechanism may` be used in connection with any type of compressor and any type of unloading means as desired without departing from the spirit of the present inventio the type of compressor shown in the drawing is merely as an illustrating example.

The pressure operating mechanism 3 comprises a cylinder 4 in which is mounted a piston 5. The piston 5 acts on the plunger 6 so that when pressure 4 behind the piston 5 it will force the plunger `6 downwardly and hold the suction valve 2 open,

ttlng the compressor I to operate in a completely unloaded condition. when the pressure ing ofthe electric magnetic action fluid is admitted to the cylinder 'Y and the spring 26 moves (Ci. 23o-31) is relieved behind the piston 5 the spring 1 forces the piston 5 and plunger 6 outwardly, relieving the pressure on the suction valve 2 and permitting the compressor to operate in normal loaded condition. f

The compressor I is operatedi by an electric motor 8 which receives its energizing power through the power lines L1 and L2. A switch 9 is interposed in the power line for controlling the energizing and deenerglzing of the motor 8. 10

The loading and unloading mechanism comprises a control valve structure Ill which is connected through suitable piping II with the receiver I2 for providing'air or gas under pressure for operating the unloading mechanism- 3. The 15 valve III comprises the valve housing I4, in which .is mounted the two valves I5 and I6, cooperat ing respectively with valve seats I'I and I8. The vpressure uid supply pipe II opens into the bore I9 of the valve housing I4 near one -end and outwardly of the valve I5, while the pipe 20 which conducts the operating pressure fluid to the valve actuating mechanism 3 opens into the bore I9 bet'ween the valves I5 and I6.

With the valves I5 and I6 in the positions 25 shown in Figure 2 of the drawing, the portion of the bore I9 between the valves I5 and I6 is opened to atmosphere through the exhaust passage 2I and the pressure fluid bleeds from the valve actuating mechanism pipe 20 and to atmosphere, permitting 'the spring 6 to act for relieving the pressure on the valve strip 2 at which time the compressor is\\operating in a loaded condition. When the valve I6 is seated and the valve I5 is of! its seat the pressure 35 uid passes around the valve I5 through the bore I9 outwardly through the pipe 2li to the valve actuating mechanism 3 and holds this valve open. The valves l5 and I6 are connected for movement in unison by a stem 22 which has a contact disk 40 23 on its outer end. The contact disk 23 is engaged by the button orf knob 24 on the pivot lever 25, The pivot lever 25 is moved by the energizcoil 26, being attracted by the of the coil into engagement with 45 the core 21 and when it is so moved it actuates the stem 22 to 4seat the valve I5 and move the valve I6 oi its seat. Thus when the coil 26 is energized the compressor I operates in a loaded condition. When the coil 26 is (le-energized, the 50 lever 26 moves away from the core 21 of the 'coil A the valve I5 oi its seat and the valve I6 on to its'seat, thereby opening receiver pressure to the!y valve actuating mechanism 3 and unloodisthe compressor, Iteis to j 3 back through the 80 be understood that in actual practice the lever 2E may be positioned so that it will move or fall away from the core 2l under its own weight and that the showing in Figure l of the drawing is t g n. ti,

.l f of a compressor itis always desirable to relieve the motor 8 and the compressor l of the load torque until both the motor and the compressor reach full operating speed and to permit of this action, thermal means are provided to cause a time interval delayY hetween the en of the motor d and the loading of the compressor.

It has heretofore been the practice to provide various types of means for providing this time interval delay such as dash pots, and other similar mechanical devices, but the present invention embraces the provision of a thermostatic switch in the form of a bimetal contact carrying member which controls the operation of the valve lo thereby providing' al simple, inexpensive, readily replaced and accurate time delay means which is much simpler in construction and cheaper to manufacture than the time delay means heretofore employed.

The time delay means 3Q includes, a bimetal plate 3l of approved usual construction which acts under temperature diierences to move the contact 32, carried thereby into engagement with the stationary contact 33' to close a circuit through the coil 26 which circuit is broken at predetermined times as hereinafter referred to. The bimetal blade 3l of the thermostatic switch 3l is electrically heated by an electric heating coil 33l which is in circuit vwith one oi the power lines:

to the motor.

aieaeos supply of operating pressure fluid to the valve ac mechanism 3 and permits the loading of the compressor. The lever 25 has an extension 4d thereon which, when the lever 25 moves towards the lcore 2l, engages the spring member G5 of the switch 3l and operates the switch blade v 38, moving it out of engagement with the contact 36 and into engagement with the contact $6, thus cutting oli the electric circuit through the coil 33 and maintaining the circuit through the coil 26 to hold the lever 25 and valve` I0 in compressor loading position, the circuit through the coil 26 being maintained by the connection tl with the contact B6. The heating coil 33 cools when the circuit is broken therethrough, which allows the blade 3l of the thermostatic switch 3B to cool and move out of engagement with the contact 33', thus positioningthe thermostatic switch for reoperation the next time the compressor is started.

' While a particular construction of valve l0 and compressor unloading mechanism is shown in the drawing and hereinbefore described, it is to be understood that the present invention of utilizing a thermal means ora. thermostatic switch for controlling the loading and unloading of the compressor maybe employed in connection with various other practical types of valves and un- ,In operation, when the-compressori is rst started by the closing of the switch 9, the bimetal bladel of the thermostatic -switch 30 will be cold and consequently the contacts! and 33 will be out of engagement. With the closing of the switch 9 the circuit is through the wire 34,

trcal circuit is then from the power line L1.

through the wire 34, wire 4l through the coil 25, the wire 42, wire 63, contacts 33' and 32, back through the wire B0 to the power line L3. ThusV the coil 26 is energized and acts on the lever 25 to move it into engagementwith the core 21. '111e movement of the lever 25 actuetes the valve structure l0 as heretofore described to cut oif the varound-through the heating coil 33, through the loading systems now generally known to the trade, without departing from the spirit of the present invention.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claim.

What is claimed is: y

Inacompressor unloading mechanism, the combination, of an air or gas compressor, an electric Y motor for operatingsaid compressor, means controlling energizing of said motor, pressure operated means for unloading said compressor, a valve for controlling the delivery of operating pressure to said pressure operated means, electrically operated means for ,operating said valve, a thermostatic switch for controlling energizing of said electrically operated means, and a switch in circuit with said thermostatic switclzgand said electrically operated means for cutting the thermostatic switch out of the circuit at predetermined times and the circuit through said electrically operated means, said electrically operated valve operating means including a magnetic coil, a lever actuated by said coil for operating Vsaid valve said lever operating said switch upon movement- 'of. the lever under action of said magnetic coil.

STEVEN F. EVELYN.'

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