COMPRESSOR OUTPUT CONTROL APPARATUS

• US 3,653,783 A
• Filed: 08/17/1970
• Issued: 04/04/1972
• Est. Priority Date: 08/17/1970
• Status: Expired due to Term

• Current Assignee: Earl R. Sauder
• Original Assignee: Earl R. Sauder
• Inventors: Sauder, Earl R.
• Primary Examiner(s): Husar, C. J.
• Assistant Examiner(s): Sher, Richard J.
• Application Number:
  US05/064,398
• Time in Patent Office: 596 Days
• Field of Search: 417/300,307,443,444,445,446,505,298
• US Class Current: 417/298
• CPC Class Codes: F04B 49/022 by means of pressure

Abstract

A control apparatus for selectively varying the output of a reciprocating compressor by holding open its suction valves for variable periods during the piston cycle. The apparatus includes a signal generating means for applying successive signals to a transducer which holds open the suction valves for a period proportional to the interval between signals. The signal generator has a rotating bar driven in timed proportion to crankshaft speed and first and second signal generating pickups positioned adjacent the path of the rotating bar so that passage thereby generates an output signal. The angular position of the second signal pickup is selectively varied to vary the time interval between signals and thus the time within the piston cycle that the compressor is unloaded. The angular position can be manually varied or automatically varied in response to changes in compressor output through a fluid pressure responsive actuator.

Claims

1. A variable output control for a reciprocating compressor comprising, in combination, an unloader mechanism for holding open a suction valve of a compressor cylinder to thereby unload that cylinder and a controller for selectively actuating and deactuating said unloader mechanism relative to the position of the piston of said compressor cylinder throughout a variable range of piston positions, said controller including a coupling bar driven about an axis in timed relation to compressor speed, a first electrical sensing element fixed adjacent the path of said coupling bar and effective to generate an energizing signal when said coupling bar passes thereby, a second electrical sensing element positioned adjacent the path of said coupling bar and effective to generate a de-energizing Signal when said coupling bar passes thereby, advancing means for rotating said second sensing element about said axis to change its angular position relative to said first sensing element whereby the time interval between said energizing and de-energizing signals may be varied, and means for applying said signals to said unloader mechanism such that said energizing signal will actuate said unloader and said de-energizing signal will deactuate said unloader in timed proportion to the relative angular position between said sensing elements.

2. The compressor output control of claim 1 wherein said second electrical sensing element is secured to a disc rotatably journaled about said axis and having a range of angular rotation relative to said first sensing element such that time between successive signals generated by said rotating coupling bar will be varied in proportion to the angular distance between said first and second sensing elements.

3. The compressor output control of claim 1 wherein said advancing means for rotating said second sensing element comprises a fluid pressure responsive element operatively connected to said second sensing element and effective to advance the angular position of said second sensing element in response to fluid pressure variations upon said pressure responsive element.

4. The compressor output control of claim 3 wherein said fluid pressure responsive element is connected to the output from said compressor whereby variations in said compressor output pressure will control movement of said second sensing element.

5. The compressor output control of claim 1 wherein said advancing means for rotating said second sensing element about said axis comprises a plunger journaled for reciprocatory movement along said axis between first and second positions, means biasing said plunger towards said second position, a pressure responsive fluid diaphragm secured to said plunger and adapted to move said plunger against said bias means towards its said second position, and means coacting with said plunger effective to advance the angular position of said second sensing element in proportion to movement of said plunger along said axis.

6. The compressor output control of claim 5 wherein said second sensing element is secured to a disc rotatably journaled about said axis and circumjacent said plunger, a sleeve secured within said disc circumjacent said plunger, a spiral groove on said plunger within said sleeve, and a detent on said sleeve extending into said spiral groove whereby axial movement of said plunger causes rotary movement of said sleeve, disc and sensing element as said detent moves within said spiral groove.

7. A control apparatus for varying the output of a reciprocating compressor having a reciprocating piston driven by a crankshaft and suction and discharge valves, said control apparatus including a suction valve unloader for holding open the suction valve to thereby unload the piston, and means for selectively actuating and deactuating said unloader for variable periods during the piston cycle, said means comprising a rotating signal element driven about an axis in timed relation to compressor crankshaft speed, a first signal sensor secured adjacent the path of said driven element and effective to generate a first signal as that driven element passes thereby, a second signal sensor positioned adjacent the path of said driven element and effective to generate a second signal as that driven element passes thereby, means for changing the angular position about said axis of said second sensor relative to said first sensor to thus change the time interval between said first and second signals a signal responsive transducer effective to actuate and deactuate said unloader upon receipt of said first and second signals respectively, and means for applying said first and second signals to said transducer whereby said compressor output will be varied in proportion to the time interval between said first and second signals.

8. The control apparatus of claim 7 wherein said rotating signal element is a ferrous bar and said first and second signal sensors are inductive windings.

9. The control apparatus of claim 7 wherein said means for changing the angular position of said second signal sensor is a fluid pressure responsive means whose position is varied in proportion to the output from said compressor and whose position variations control the angular position of said second signal sensor.

10. The control apparatus of claim 7 wherein said means for changing the angular position of said second signal sensor comprises a plunger journaled for reciprocatory movement along said axis between first and second positions, means biasing said plunger towards said second position, a pressure responsive fluid diaphragm secured to said plunger and adapted to move said plunger against said bias means towards its said second position, and means coacting with said plunger effective to advance the angular position of said second signal sensor in proportion to movement of said plunger along said axis.

11. The control apparatus of claim 10 wherein said second signal sensor is secured to a disc rotatably journaled about said axis and circumjacent said plunger, a sleeve secured within said disc circumjacent said plunger, a spiral groove on said plunger within said sleeve, and a detent on said sleeve extending into said spiral groove whereby axial movement of said plunger causes rotary movement of said sleeve, disc and sensing element as said detent moves within said spiral groove.