US1606060A - Compressor-controlling apparatus - Google Patents

Description

Nov. 9 1926. 1,606,060

C. E. COX

COMPRESSOR GONTROLLI NG APPARATUS Filed May '7: 1924 2 Sheets-Sheet 1 d2 FROM All? KECEIVER Q 2 pmswrae y Clarence E. COX

Nov. 9,1920. 0 1,606,060

c. E. c ox COMPRESSOR CONTROLLING APPARATUS Filed May 7. 1924 2 Sheets-Sheet 2" FROM AIR RECE/ v5? C/a/re/vce f. COX y Patented Nov. 9, 1926.

UNITED STATES PATENT OFFICE.

r CLARENCE E. COX, FRANKLIN, PENNSYLVANIA, AS SIGNOR TO CHICAGO PNEU- bustion engine/to drive the compressor.

MATIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

COMPRESSOR-CONTROLLING APPARATUS.

Application filed Kay 7,

/Ihis invention relates to apparatus for controlling the operation of fluid compressors, pumps andthe'like. It has particular application to the loading and unloading during starting andestopping periods of air compressors arranged :tor intermittent op? eration.

. Certain typesof prime movers used to operate compressors are relatively ineflicient under certain conditions, as when start ing, when operating at low speeds, or in a cold condition. The electric motor, which is a particularly desirable type of power unit tor the intermittent operation. of compressors, is characterized by a relatively low "starting torque, especially the alternating current motor, and by an inability to carry its load until it has attained its operating speed. Hence when an electric motor forms the driving element efiicient and positively operating apparatus for maintaining the compressors in an unloaded condition during the starting and stopping periods is a requisite. Such apparatus isdesirable also on installations utilizing an internal com- Oneof the objects of the invention is to provide simple and reliable apparatus of the described type which will operate in an eflicient and positive manner during the starting and stopping periods. Another object is to prevent loading of the compressor in case the driving engine fails to at tainits operating speed. Other objects will be apparent from the detailed description which follows. p

The invention comprises utilizing a builtup pressure which varies in proportion to and closely approximates in time the variations in speed of the compressor for controlling suitable unloading mechanism on the compressor. It may take advantage of the fact that the fluid pressure developed by a gear type rotary pump is a function of its speed when some throttling efl'lect is produced in the discharge line from the pump.

The fluid pressure medium may be from a circulating system associated with the compressor as its cooling orits lubricating system, or from a system specially designed for compressor pontrol. I

order to make clear the nature of the j invention and the manner. of its operation, concrete embodiments of the genus constiholding the 1924. Serial N0. 711,558.

tuting the invention are disclosed in the accompanying drawings, in which: Fig. 1 is a side elevational view of a compressor partly cut away to disclose an"'un loading valve and showing the contro1 mechanism for the latter in section' as on the 1ine-1-e1..ofmEig. 2;

Fig. 2 is an end elevation view of the parts shown in Fig. 1 with the control mechanism disclosed in section substantially on the line 22 of Fig. 1; and

Fig. 3 is a view similar to Fig. 2 showing a modified form of control mechanism.

The invention is disclosed as applied to a compressor of the air cooled type and its lubricating system is selected, merely by way of illustrating the invention and not for limiting it, to provide the fluid pressure medium utilized for the automatic control of the loading and unloading of the compressor. Referring now to the drawings, A is the compressor having fly wheel B, the same being driven by any suitable type of prime mover (not shown), such as an electric motor. The fluid circulating system for lubricating the compressor includes a suitable pump C,'preferably of the gear type, connected to the shaft of the compressor by a suitable coupling (not shown), the pump having an inlet connection 0 leading to the sump or lubricating reservoir a at the baseot' the compressor and an outlet connection leading to the splash trough a and if desired toother parts requiring lubrication, this outlet connection comprising two parts, the' one 0 leading to the casing .4 of the control mechanism later 'to be described and the other 0 from casing 4; to

splash trough a. i

The compressorhas one or more fluid 0perated unloading valves D of any suitable or desired type, the one illustrated being the well known plate unloading valve disclosed in U. S. Patent No. 1,27 5,843 issued August 13, 1918, to William H. Callan.- The unloading valve D comprises essentially a cylinder at having a piston d movable therein in one direction by motive fluid admitted through a pipe connection (2 and arranged to actuate the fingered valve litter d, for plate valve d ofl its apertured seat (1, the hfter d. and the piston 0'! being returned to inoperative position by a spring The automatic control mechanism for the unloading valve D comprises the casing 4 having a vertically disposed cylindrical bore 5 therein, within which there is arranged for reciprocatory movement a double headed piston 6, the heads 6 and 6 of which are connected by a stem 7 and form therebetween a chamber 8 provided with a constantly open outlet port 9 which communicates with the fluid connection 0Z extending to unloader valve D. Piston head 6 performs the function of a valve in controlling an inlet port 10 from which a pipe 11 leads to the air receiver (not shown) supplied by the compressor. The piston head 6 likewise functions as a valve in controlling a VBIItpOIt 12 leading-to atmosphere. The double headed piston or control member 6 is normally retained in its lowermost position as shown in Figs. 1 and 2 by a loading spring 13, one end of which spring is received in a socket inthe head 6 .and the other end engages a centering projection on the interior of a range adjusting nut 14 in threaded engagement with the casing 4. The double headed piston 6 has on its lower end a projectin stem 15 adapted to engage the bracket 1% which supports the casing 4 andv closes the I lower end of the cylindrical bore 5. There is thus provided in the lower end of bore 5 and below piston head 6 a chamber to which the lubricant issuing from pump C has access through its outlet pipe 0' by means of a horizontal bore 16. Casing 4 above bore 16 has a vertical bore 17 joining bore 16 by a reduced opening 18 thereby formin a seat 19 for a check valve in the form of a all 20 urged toward its seat by a spring 21,'the tension of which may be adjusted by a screw 22 threaded into the upper end of bore 17. A washer 23 and lock nut 24 hold screw 22 in adjusted position- A vent 18' leads past check valve 20 into bore 17 to which the sec- 0nd part or section 0 of the outlet pipe from disclosed through pipe d outlet 9, chamber 80f the control device, inlet 10 and pipe 11 which connects with the air receiver. Thus the compressor is entirely unloaded. When the prime mover for the compressor isstarted,

pump 0 immediately begins to force oil from d the sump a into casing 4, the oil discharged by the pump entering bore 16 and the chamber below the piston head 6 of the control device and being vented through opening 18 to bore 17 and thence through pipe 0 to the splash trough a' With, the development of pressure spr g 21 of heck valve threaded engagement therewith.

20 yields, being of much less resistance than of the spring 13 is overcome whereupon the double ended piston control member 6 moves upwardly, piston head 6 closing air inlet 10 and piston head 6 uncovering vent 12 whereupon the motive fluid which has previously acted on piston 03 of the unloader valve D is exhausted, and plate valve ol is thereupon released to function as an inlet valve and the compressor is loaded. In the upward movement of member 6 the end of stem ,15

is exposed, thus increasing the area subjected to the pressure of the lubricating system so that member 6 moves quickly and positively to its upper position. Thus control member 6 through its stem 15 has a differential area subjected to the pressure in the lubricant.

When the pressure in the lubricating system falls through reduction in compressor speed, spring 13 restores control member 6 to its original position so that chamber 8 is again closed to atmosphere and opened to motive fluid from pipe 11 and unloading valve D is placed in operation.

In Fig. 3 a modified form of controldevice is shown, the principle of operation, howevenbeing substantially the same. The control device comprises a casing 25 having a large horizontal bore 26. and a. smaller vertical bore 27 provided witha reduced extension 28 joining bore 26 and forming a seat for a check valve 29 which has a small vent 28. Outlet pipe 0 connects with reduced bore 28 below checkv valve 29 and pipe 0 with bore 27 above the check valve. Within bore 26 isa piston 30 backed by a loading spring 31 and a vented range adjusting nut 32, these parts closing one end of bore26. The other. end of bore 26 is closed by a'casing 33 in Casing 33 has a horizontal bore 34 at its outer end with a reduced extension 35 coaxial with bore 26 and communicating therewith. Within chamber 34 is a-valve 36- cooperating with a seat at the entrance to bore 35 and having a reduced stem 37 provided with a cylindrical end 38 tit-ting bore 35 and arranged to control a vent port 39 and to engage a projection 40 on piston 30 which projection has a bevelled edge which seats in a similarlyt bevelled socket 41 in casing 33. A spring Ill (1 leading tounloader valve D. Projection 40 on piston 30'ope rates to make the latter a 'difi'erential piston in the same manner that stem acts in the modification shown in Figs. 1 and 2.

v The operation of the modification shown in Fig. 3 will be apparent from the draw-' 'ing as a valve uncovers vent 39 to relieve the unloading valve D and to permit the latter to function as an inlet valve. When the pressure in the lubricating system falls,

the Fi 7 mm the above it will be apparent that both forms of the invention herein disclosed provide simple and positively operated means for maintaining a compressor in unloaded condition when the same is operated the check valve and the amount of flow thereby adapt the compressor to use with prime movers having widely varying power characteristics. p

Having now described my invention and the manner of its use, whatIclaim and desire to secure by Letters Patent is:-

1. In combination, a compressor having a lubricant circulating system operating in proportion to the speed of the compressor,

including a pump and a chamber into which the pump discharges. a valve yieldably opposing the passage of fluid from said chamber, a restricted by-pass around said valve to permit a circulation of said fluid at all times a fluid pressure operated unloader for said parts return to the position shown in compressor, and means responsive to built up pressure of said fluid in said chamber for controlling the admission of motive fluid to said, unloader to actuate the same.

2. In combination, a compressor having a liquid circulating system operating in proportion to the speed of the compressor including a pump and a chamber into which the pump discharges, a valve-yieldahly opposing the passage of liquid from said chamber, means for varying the resistance of said valve to the passage of said liquid, a'restricted by-pass around said valve to permit the circulation of said liquid at all times, an unloader for said compressor, and means responsive "to the pressure of said liquid in said chamber for controlling said unloader.

liquid circulating system operating in pro- .portion to the speed of the compressor including apump and a chamber into'which the pump discharges, a valve for op osing the passage of liquid from said cham er, a spring arranged to press said valve to its seat, means for adjusting the tension of said spring, an uirloader'for said compressor, and means responsive 'to the pressure of said liquid in said chamber for controlling said unloader. I

(i. .A controlling device for compressors having fluid operated unloading means and lubricant circulating systems comprising a casing having a chamber forming a part of the lubricant circulating system, a valve yieldingly controlling the outlet of said chamber to cause the lubricant to build up pressure in said chamber, means for adjustably predetermining the yielding tension on said valve, a restricted by-pass around said valve to insure circulation in said lubricant system at all times, a piston movable in 3. In combination, a compressor having a response to the built up pressure in said chamber, adjustable meansfor yieldingly opposing movement of said piston, and valve means carried by said 'piston and arranged to connect the unloadingmeans of the compressor either to a source of fluid pressure or to exhaustdependent upon the position of said piston.

Signed b me at -Franklin,'-Penna., this 30th day 0 April, 1924.

p CLARENCE E. COX.

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