US1543680A - Centrifugal unloader - Google Patents

Description

June 30, 1925. .7 1,543,686"- s. B. REDFIELD CENTRIFUGAL unnowmi Filed lay'2, 1923 5 Elects-Elect 1 HHS ATTOR Y Julie 30, 1925'.

5. B. REDFIELD' CENTRIFUGAL UNLdADER y 2, 1923 3 Sheets-Sheet 2 Filed M a INVENTOR nowanaflafwzd.

H I 5 ATTORN June 30, 1925. I 1,543,680 j S. B. REDIFIELD I CENTRIFUGAL URLOADER Filedlay 2, 1923 3 Sheets-Sheet 5 HIS ATTOR Y drawings.

Patented June 30, 1925.

UNITED STATES PATENT oFFloa.

SNOWDEN B. BEDFIELD, OF EASTO'N, PENNSYLVANIA, ASSIGNOR TO INGERSOLL RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

CENTRIFUGAL UNLOADER.

Application filed Kay 2,

To all whom it may concern."

Bef'it known that l, SNOWDEN B. RED- FIELD, a citizen of the United States, a resident of Easton, county of Northampton, and State of Pennsylvania, have invented a certain Centrifugal Unloader, of which the following is a specification, accompanied by This invention relates to compressor unloaders, but more particularly to an unloader for relieving the fluid compression load during the period of starting. The objects of this invention are to enable a compressor unloader to be controlled by the speed of the driving element of the compressor.

Further objects of the invention will hereinafter appear, and the invention is shown in the accompanying drawings in one of its preferred forms, in Which Figure l is a side elevational view partly in 'section of a compressor unit with my invention applied thereto,

Fi ure 2 is a view similar to Figure 1 showing the parts in running position,

Figure 3 is a diagrammatic view, partially in longitudinal section of an unloader with a' modified form of my invention applied thereto, and v Figure 4 is an enlarged detail view partially in vertical section of the choking needle valve,

Referring to the drawings, the compressor comprises the cylinder A, in which a piston (not shown) reciprocates. Thedriving element for thecompressor piston comprises the crank shaft B, mounted in the frame B to which the connecting rod C is attached for moving the cross head D. The fly wheel E is secured in any suitable manner tothe crank shaft B.

The unloader F is connected to the discharge line G between the compressor and the usual receiver H. The unloader comprises a valve casing J having a main valve chamber K separated from the outlet L by a partition 0 on which the main check valve P is adapted to be seated for controllin the discharge from the casing. The chec valve P is provided with a spring Q bearing on the valve and held b a cap R, which cap also forms a valve gui e. The pressure in the receiver tank H normally holds the main check valve P to its seat, when the "compressor is idle.-

1923. Serial No. 636,080.

the communication between the main valve chamber K and an atmosp'hericrelief port V, conveniently located on the side of the extension W of the main casing J, in which the reliefvalve U operates, The relief valve U. is preferably carried by a piston X and has limited longitudinal movement relatively to the piston, being urged outwardly from the piston X by a comparatively heav coil spring Y, in the valve socket 'Z, of su ficient strength to resist the full line pressure in the main valve chamber K and revent the relief valve from opening against the spring due to said pressure, when the Valve is held to its seat by the combined spring pressure and fluid pressure behind t e piston X. The movement of the relief valve is limited by a pin a passing through the transverse aperture 6 in the valve, and secured at each end of the valve piston X, The piston X is of the difi'erential type, provided with an enlarged head 0 forming a pressure area materially greater than the opposed pressure area on the face of the relief valve U and pressure behind the piston head 0 will force the relief valve U to its seat T with sufficient force to compress the spring Y and also hold the piston head 0' firmly against theseat a? in the extension W, so that leakage past the piston from behind the piston head is prevented. The relative longitudinal movement provided be- .,tween the relief valve U and the piston X, enables both the valve and the piston to be tightly seated on their seats T and d respectively.

A projection or stop 6 on the piston X is adapted to bear upon an adjusting screw 2 in the cap g, by means of which the initial starting position of the piston X and relief valve U may be adjusted. A bypass itto operate for loading. Adjustment of the screw f behind the piston X determines the pressure'to which the side discharge to atmosphere through the port or vent V will be built up by the relief valve U by the time the compressor has reached full speed. This adjusting screw f should preferably be set at a point to produce just enoug throttling at the relief valve U to move the piston inwardly and close the relief valve U when the choking needle valve k is set well towards its seat in the port 9'. Throttling, due to the slightl open relief valve U needs :not be considera 'le, but should be at least a pound or two, in order to start building up an initial pressure behind the piston X to begin moving the piston X and relief ,valve U towards the seat T to close the outlet to atmosphere through the port V. r

A valve casing o in this instance supported by a'column p, is provided with an a-tmosp eric vent g. A plunger valve 1' is adapted to be moved longitudinall in the bore 8 of the valve casing 0. A coi spring t, the ten- .sion of which may be adjusted by the set screw'u, bears against one end of the plunger ,valve 1'. The bore 8 of the valve casing 0 is in communication with theextension W of the main valve casing J, rearwardly of the piston X, by means of a pipe or tube '0. It

will readily be understood that when the compressor is idle, the space in the rear of the piston X in the extension W of the main valve casing, will be open to atmosphere through the pipe or tube 0, the bore a of the valve casing o and the atmospheric vent q. By moving the plunger valve r to the left, as shown in Figure 2, the passage of fluid to atmosphere from behind the piston X will be revented.

frame 'w is secured to the crank shaft B of the compressor by any suitable means, as screws 'w'-. A plurality of weighted bell crank levers ware mount d on the frame 10. Thesmaller unweighted nds w of the levers a: are in contact with a collar 3 which is v adapted to be moved longitudinally on the shown in spindle 2. 1s threaded into the crank shaft B. Theextension 3 of the collar 3 is adapted to bear against one end of the plunger 1'.

Assuming that the compressor is starting, the'imtial osition of the arts will be as lgure 1, and fluid pressure will be forced out to atmosphere through the vent V in the extension W of the main valve casing, and a portion thereof will as from the main valvechamber K, throu the passage h, ort j, pipe or tube-'0, t ough the bore 8 o the valve casing O and out through the atmospheric vent g. As soon as sufficient speed has been attained, centrifugal force will cause the Weighted bell crank levers as to fly outwardly as shown in Figure 2, and by means of the collar 3 and extension y,

The spindle z in this instance,v

Pressure through the vent V. Sufficient pressure will then be built up in the valve chamber Kto overcome the receiver pressure and unseat the valve P in order to force the fluid pressure into the receiver H. 1

As the compressor stops, the above described operation will be reversed. The

Weighted levers m will tend to assume their normal or inward position, and thereby permit the coil spring t to move the plunger valve 1- to the right, and open the passage of fluid from the extension W of the main valve casing in rear of the piston X to atmosphere through. the port 9 in the valve casing 0. Pressure fluid Will be allowed to pass out of the tube '0 and vent q faster than it can enter the space back of the piston head 0 through choking needle valve is. This will reduce the fluid pressure back of the piston head 0 to such a point that the pressure in the main chamber K will unseat the relief valve U, thereby allowing fluid to pass out through the atmospheric vent V. Load will thus be thrown ofl the compressor and enable the compressor piston to restart unloaded.

In the modification shown in Figures 3 and 4, the same principle heretofore described is applied to an unloader in which the /passage 72. in the extension W of the main valve casing is omitted. In this instance, the pipe or tube 2 is connected to the main valve chamber K and is in communication with the valve casing 0', which is supported in any suitable manner, as by the angle bar 1). The bore 8 in the valve casing o communicates 'with the smaller bore t which is in communication with the pipe or tube '0'. The opposite end of the pipe or tube '0' is connected to the extension W of the main valve casing rearwardly of the piston X. A ball check valveu urged against its seat It by the coil sprin u con-' trols the passage of pressure fluid, om the main valve chamber K to the rear of the piston X. A ball check valve :12 in the bore 2 of the valve casing o' is spaced from the all valve u by the spacer pin 2' and controls the atmospheric vent 3.

A plate 4 secured in any suitable manner to the end of the compressor shaft 5 as b means of the screws 6, is provided with the lugs 7. The weighted bell crank levers 8 are pivotally mounted on the ln 7, and are adapted to bear against the end 9 of the lunger 10 for moving the plunger inwar y, in the casing 0'. The inner end 11 of the plunger 10 is adapted to'bear against and seat the ball -valve A coil spring 12 is secured at its ends to the ins 13 in the levers 8, and serves to hol the levers 8 Assuming that the compressor is starting, I

the wei hted levers will e caused to move outwargly b centrifugal force, and thereby move the p unger 10 inwardly to seat the ball valve :12. By means of the spacer z,

1 the ball valve to W111 be unseated' thereby permitting fluid pressure to flow from the main valve chamber K" through the pipe or tube 2int0 the bore ,9 of the valve casingo,

\ through the bore the ba 1 valve u and b means 0 the spacer the main valve casing.

t and thence through the pipe or tube 0; to The iston X will thereupon be forced in-v war y, forced to its seat T, thereby closing the atmospheric vent V in the extension W" of On stoppin the levers 8 will tend to move together by t e action of the coil spring 12, thereb permitting the coil sprin u to seat pin 2', unseat the b valve 0:. Pressure fluid may then pass from behind the piston K through the pipe or tube '0 into the bore t of the valve casing o and thence to atpassing choking p s g V rectly from the compressor an controlling.

"a centrifugally oper- 5 valve with atm v ing adapted .to control the mospherethrough the vent 3.

As shown in Figure 4, I provide a set screw 14 preferably threaded'mto the main valve chamber K forming a choking needle valve, which controls the amount of fluid I out of the main valve chamber. K into the pipe or tube 2. Byregulating the needle valve, the closing the relief valve U may be delay or has- 1. A- centrifugal compressor unloader a 'rehef 'valve in. the dischai' e line exposed on both ends to ressure a vent to atmosphere, able pilot valve, and a conduit connecting one face of the reliefvalve through the pilot here, said pilot valve bethe rear of the piston X;

and the relief valve U will be.

oint of opening of said -ebnduit to atmosphere whereby the relief valve is arranged to be actuated.

2. A centrifugal compressor unloader comprising a. relief valve in the discharge line exposed on both ends to pressure directly from the compressor and controlling a vent to atmosphere, a centrifugally operable pilot valve, and a conduit connecting one face of the relief valve through the pilot valve with atmosphere, and adjustable means restricting the flow of air to and from one side of the relief valve.

3. A centrifugal compressor unloader, comprising an unloader mechanism adapted to be connected in the discharge line 'of the com ressor, said unloader mechanism comprising a main discharge valve casin provided with a discharge valve cham r, "a main discharge valve controlling the outlet from the casing, an extension connected to said casing, a piston in the extension, a relief valve havm limited movement in the piston, adapte to control an atmospheric vent in the extension, a connection between the discharge valve chamber and the space in rear of the piston, a choking valve controlling the tion, centrifugal means for controlling the o eration of the unloader mechanism operatively connected to the drivin element of 'the compressor comprising a ame, a plurality of weighted bell crank levers pivotally. mounted on the frame, a spindle ured to the frame acollar provid with n extension slida ly mounted on the spindle, the movement of the collar on the s ing controlled by one end of the 11 crank levers, a plunger valve casing-in communication with the extension of the main valve casing rearwardly of the piston, a' plunger valve vin the plunger valve casing-adapted to be moved in one direction by said extension for controlling an atmospheric vent therein, a spring in the plunger valve casing opposing the movement 0 theval-ve in 'one d rection, whereby" the load is thrown on and oi the compressor in accordance with its speed. v In testimony whereof I have signed this specification a i. SNOWDEN B. REDFIELD.

indle be-

Images