US2329931A - Compressor control means - Google Patents

Description

p 1943- c. R. NEESON 2,329,931

COMPRES SOR CONTROL MEANS Filed Nov. 26, 1941 SSheets-Sheet 1 E N T R 6B%drzes 75. N gro-41x N 022.4, Giza 8,- NW...

ATTORNEY5' Sept. 21, 1943. c. R. NEESON COMPRESSOR CONTROL MEANS Filed Nov. 26, 1941 3 Sheets-Sheet 2 INVENTOR BY NM xii, 124 f ATTORNEYS.

Sept. 21, 1943.

C. R. NEESON COMPRESSOR CONTROL MEANS Filed Nov. 26, 1941 3 SheetsSheet 3 All e a J z r h C Y B 1 k.

Patented Sept. 21, 1943 PATENT OFFICE COWKESSOR CONTROL MEANS -Cles R. Non, Dayton, Ohio, assignor to Chrysler Corporation, Detroit, Mich, a corporation of Delaware Application November 26, 1941, Serial No. 420,559

2 Claims. (Cl. 230-24) My present invention relates to the control of compressing means for compressing a gaseous cally comprises an improvement upon the come pressor unloading means disclosed and claime in my Patent No. 2,185,473, issued January 2. 1940, but, as will presently appear, the invention hasv application in a variety or forms of compressors. 1 f

One object of the invention is to provide means for preventing the loading oi acompressor until a predetermined time interval after commencement of cyclical operation of the compressing mechanism. A compressing mechanism usually comprises a suction valve and a discharg valve operating inconjunction with a piston, which parts go through cycles of operation including the drawing of gas through the suction valve, compressing thereof by the piston and discharge of the compressed gas through the discharge valve. A compressor may comprise a single piston and set ofvalves or it may comprise a plurality of pistons each with its own set of valves.=

In the present disclosure the compressor comprises a. plurality of reciprocating pistons, each with its own set of valves, located radially about the compressor crankshaft. In accordance ,with

the present invention a single compressing means or a plurality of compressing means may be controlled to prevent the application of load to the prime mover, i. e., to prevent the compression of the gaseous medium, until a predetermined length of time after commencement of cyclical operation of the compressing means.

The principal purpose of the present invention is to permit the application of an inexpensive type of motor, or other primev mover, to the driving of gaseous medium compressors. By preventor fuel consumption of the prime mover is matelially reduced. This is of special importance in some localities where the consumer charge for useor electric current is based upon the starting inrush current peak. It the starting inrush is Just sufllcient to overcome the inertia of the rotor v and operating parts of the compressing means,

the stand-by charge or peak load charge may be;

materially reduced.

A further object of the-present invention is to Q provide means automatically and instantaneously to render the compressing means inoperative until a predetermined time interval after stoppage of the prime mover. This i of particular importance in certain installations-wherein a repeating starter may be employed, such as, for example, in a compressor connected to an internal combustion engine provided with an automatically repeating starter mechanism which is designed to operate a plurality of times in spaced succession provided the internal combustion engine does not immediately start. Such mechanisms fail to take into account the fact that the reason for inability to start the internal combustion engine might be the inability of the starting motor to carry the compression load as well as to overcome the inertia of the internal combustion engine and the compressor. In the present invention, upon cessation of cyclical operation of the compressing means, the compressing means is immediately rendered ineffective to compress. the gaseous medium and remains in such ineffective state for a predetermined length of time which may be such as to exceed the length of time required for the engine to reach full speed.

A further object of the present invention is to safeguard the rotor or other portions of electric motors employed to operate refrigerant compressing means. It sometimes happens, such as occasionally caused by lightning striking the power lines, that the rotor is momentarily locked against rotation due to a reversed current surge greater than the normal current supply to the motor. If, after passage of the lightning surge, the rotor is expected immediately to pick up the full compression load the windings of the motor may be so overloaded as to cause the insulation to burn and cause a short-circuit. A similar situation exists with regard to the human element in that an untrained operator or some unauthorized person may flick the starting switch on and off in rapid succession. In either event or in any other similar event, the present invention is designed to relieve the motor of the compression load until the motor has been given the opportunity to achieve full speed.

These and other objects and advantages of the present invention will be more readily apparentto those skilled in the art upon inspection of the accompanying drawings taken in connection with the following specification wherein like numerals refer to like parts throughout.

In the drawings,

Fig. '1 discloses a compressor embodying a pinrality oi compressing means. as disclosed in'my Patent No. 2,185,473, issued Janua y 2, 1940, the compressor being mounted in a condensing unit for a refrigerating system and driven by an e1ec-'- tric motor;

Fig. 2 is a longitudinal, vertical section taken through the compressor of Fig. 1, certain parts of the sectional view being on irregular planes for the purpose of complete disclosure;

Fig. 3 is a vertical section through a time delay relay comprising a portion of the present invention;

Fig. 4 is a vertical section through a valve comprising a portion of the present invention.

Fig. 5 is an axial section through one of the compressing cylinders and pistons; and

Fig. 6 is a horizontal section through the master valve and master valve controlling means of the compressor.

The usual condensing unit for a refrigerating system comprises a compressor i0 driven by a prime mover, in this case an electric motor II, and a condenser I2 into which the compressed refrigerant is discharged by the compressor and from which the cooled refrigerant may be withdrawn through a discharge line [3 having connection to the cooling portion of the refrigerating or air conditioning system (not shown) from which the expanded refrigerant is returned to the compressor through a suction pipe M.

It is to be appreciated that the compressor l0 may comprise an air compressor drawing air from the atmosphere through an inlet l4 and discharging the compressed air into a receiver mounted in the position of the condenser i 2.

crankpin 24 of a crankshaft 25 connected to the prime mover ll. Cyclical operation of the compressing means would normally commence instantaneously with the operation of the prime mover to draw a gaseous medium from the interior of the crankcase through the suction valve 2!, to compress the same and to discharge the compressed gaseous medium through the discharge valve as fully explained in the aforesaid patent.

The compressor of the present invention is lubricated by a pump 30 driven through gears 8i and 32, the latter of which is mounted on a shaft having driven connection to the crankshaft 25 through the medium of a pin and slot connector 33. The pump, therefore, operates simultaneously and coextensively with cyclical operation of the compressing means. The pump, as fully explained in the aforesaid patent, draws lubricant from the crankcase and forces it through an outlet 34 into a plurality of passages having communication with the bearings and manifold through port I01.

control of a metallic bellows 31 influenced by the suction pressure existing within the crankcaseof the compressor Ill. Lubricant may be passed by the master valve 38 into one of several connections 38 each leading to a space 39 containing a piston 40. The piston 40 is connected by means of a piston rod ll to a yoke 42 surrounding the cylinder wall 43 in which the piston 20 operates. The end of the yoke is provided with a roller adapted to climb a ramp 44 in order to raise a ring 45 surrounding the cylinder 43 and which is provided with a plurality of vertical rods 46. When fluid pressure is applied through the connection 38 against the piston 40 the roller in yoke 42 is lowered down the ramp 44 and the rods 46 are lowered to the position illustrated, in which position the suction valve 2| is seated so that the compressing means is loaded or will compress the gaseous medium. Upon release of fluid pressure from against the piston 40 a spring 4'! surrounding the piston rod 41 forces the piston 40 outward and causes the roller in the end of yoke 42 to climb the ramp 44, thereby raising the ring 45 and causing the rods 48 to raise the suction'valve 2i from its seat. As long as this condition exists the compressing means is unloaded since gas drawn into the cylinder through the suction valve would be forced back through the suction valve into the crankcase without compression thereof.

Reference to Figs. 5 and 6 will more completely clarify the foregoing, the figures more completely disclosing details of the mechanism. Fig. 5 shows that rods 46 are lowered by the combined thrust of springs Hill on the rods 46 and springs llll on the suction valve 2|. Valve 2| may open when the pressure within cylinder 43 is lower than the pressure existing in suction manifold I02. thus permitting gas to enter the cylinder through ports I03. More gas may enter through ports I04 when the piston is fully retracted. When the piston 20 is thrust outwardly the valve 2i closes and discharge valve I05 opens against the thrust of springs i06'held in discharge valve head 22, thus permitting escape of compressed gas into the discharge The suction manifold is connected to the space surrounding bellows 31 (Fig. 6) through ports such as port H0 (Fig. 5). Thus bellows 31 may contract or expand as the load on the refrigerating system, and hence the suction pressure, varies. Bellows 31 may fully contract against the end of guidelimit tube iii, in which position all cylinders are loaded, or may fully expand, in which position all cylinders are unloaded. The bellows is connected to limit rod H2, which extends outward and is provided with an adjustment nut I I3 which is adapted to strike the end of a tube H4 to limit the extent of movement of bellows 31 and hence limit the number of cylinders which may be unloaded. Tube H4 is slotted and the slot guides a regulator member H5 which holds one end of a regulator spring H6, the other end of which bears against the inner end of bellows 31. The position of member H5 may be set by nut ill and locknut H8, threaded onto tube H4, to regulate the pressure of spring I I6 and hence determine the range of pressures at which the bellows expands or contracts. Bellows 31 is also connected to a rod I20 pivotally connected to a rocker arm I 2! mounted on the body of master valve 36 and pivotally connected to the master valve rod 50. The master valve rod 50 is thus caused to move in ratio to the movements of the following operation thereof.

Complete details and a more detailed explanation of the individual cylinder unloading means may be found in the aforesaid patent, which also discloses more complete details and. explanation The selection of the pistons 40 which are to have fluid pressure applied thereto to cause unloading of the compressing means associated therewith is sub- Ject to a condition of the gaseous medium being compressed, such as the suction pressure existing within the crankcase of the compressor. This is efiected by the metallic bellows 31 which may expand or contract to cause movement oi themaster valve rod 60 in the master valve 36.

' Movement-of the master valve rod 50 causes connection of one or more of the connecting tubes 38 to the source of fluid pressure so 'as to cause loading of the individual compressing means to which the tubes 38 lead, or disconnection there with resultant unloading. Some or all of the tubes 38 may be disconnected, or, vice versa,

some or all of the tubes 38 may be connected to the source of fluid pressure.

When the prime mover stops in a refrigerating system the pressure in the crankcase increases. such increase soon causing complete collapse of the bellows 31 and complete connection of the unioading means to the source of fluid pressure. As soon as the prime mover starts cyclical operation of the compressing means again, simultaneous operation of the pump 30 commences. For the first few rotations of the crankshaft 25 insufficient fluid pressure is created by the pump 30 to cause movement of the pistons 40 and resultant loading of any of the compressing means. In a very short period of time, such as one-fifth of a second when the prime mover is operated by 60-cycle current at 1,750 R. P. M., suflicient fluid pressure will be generated by the pump to cause movement of all of the pistons 40 and loading of all of the compressing means. Thereafter, as the suction pressure of the refrigerat ing system is reduced, the bellows 31 expands to disconnect one or more of the tubes 38 and cause unloading of one or more of the compressing means so that the capacity of the compressor automatically varies in accordance wiht the load on the refrigerating system; hence the motor consumes power variably in proportion to the load on the refrigerating system.

In most installations the short period of time required to build up sumcient fluid pressure, oneiifth of a second in the above example representing 12 cycles of alternating current, is suflicient for the motor to overcome its own inertia and the inertia of the compressing means and attain suflicient speed to carry the full compressing load. The present invention is designed to take care of the unusual installation or to make absolutely certain that the usual installation will function, and to reduce. the starting torque in any installation.

. means comprises a time delay relay l and a by-pass valve I8 operating to break the connection between the pump 30 and the master valve 33 until it is absolutely certain that the prime mover is operating at full speed. The time delay relay 68 preferably comprises a solenoid 51, the windings of which are connected by wires 58 to the power leads of the prime mover, in the example shown to two wires of a three-phase system. The core 80 of the solenoid is provided with a piston 61 operating in a dash-pot 62, the piston 6| being provided with a metering orifice 63 and a check valve 84 so arranged as to open upwardly. Upon energization of the solenoid 51 the core 60 will be drawn upward, the rate of travel of the core being held to that permitted by the escape of fluid from above the piston 6! through the metering orifice 63. The core 60 has suiflcient travel to operate an insulated plunger which closes contacts 66 to complete a circuit including a second solenoid 61 which draws current from the power leads to the prime mover and which operates the by-pass valve 56. The closing of contacts 86 is delayed a predetermined intervalof time depending upon the rate of escape of the fluid in the dash-pot 62 after initial energization of the prime mover II. On the other hand, opening of the contacts 66 may be substantially instantaneous due to the rapid escape of the fluid through the check valve 64 when the solenoid is deenergized. It is to be appreciated that the present disclosure is relative schematic, there being many such devices for accomplishing timed closing of the contacts 66 and substantially instantaneous opening of the contacts 66.

The by-pass valve 56 preferably comprises a core Ill attached to a valve plunger H provided with an opening "of considerable length. The body ,13 of the valve is-provided with three passages", 15 and 16 in vertical alignment. The .valve 56 is attached to the crankcase cover I1,

and the openings l4, l5, and 16 are aligned with matching openings l8, l9, and 80, respectively, in the coverl'l. The opening 18 leads directly into the interior of the compressor 'so that fluid passing therethrough drains back to the pump 30. The opening 19 is connected to a tube 8| which comprises the supply tube to the master valve 36, and the opening 80 is connected to a tube 82 which communicates with the passage 35 leading to the discharge side of the pump 30.

When the solenoid 61 is deenergized due to opening of the contacts 66, the valve plunger H is in the position shown in Fig. 4 so that the output of the pump is blocked from the master valve 36. As soon as the dash-pot device has closed the contacts 66, the solenoid 6'! is energized to raise the plunger H in order to connect tube 8| to tube 82, thus causing the immediate application of fluid pressure to the master valve 36.

The present invention comprises the addition to the foregoing system of a time delay mechanism to prevent connection of the fluid pressure creating means to the fluid pressure operated loading means, until a predetermined safe length of time after commencement of cyclical operation of the compressing means. The time delay Upon such application of fluid pressure all of the pistons 40 will be operated against the springs 41 to load all of the compressing means since the master valve will have been moved to entire connecting position by collapse of the metallic bellows 31. The arrangement of the plunger H is such that immediate discontinuance of power to the prime mover or reversal of current thereto would result in immediateunloading of all of the compressing means since the plunger H would immediately drop, thus connecting the master valve to the interior of the crankcase through the opening 18 and permitting the lubrican't therein to flow out and permit the springs 41 to operate-the unloading means. Reapplication of current in the next moment would not cause reloading oi the compressor until after the dash-pot device had been overcome.

As fully explained in the aforesaid patent the operation of the master valve 38 may be accomplished by some other condition oi the gaseous medium being compressed, such as the pressure in the receiver into which the compressed gas is discharged. It should be apparent to those skilled in the art that such a modification would permit the application of the present invention to an air compressing mechanism.

It should be obvious to those skilled in the art that the present invention may be applied to the combination of a compressor and an internal combustion engine of the type having automatic starting means, such as by causing the energization of the solenoid 61 to occur simultaneously with application of current to the internal combustion engine starting motor.

It should be apparent to those skilled in the art that many other modifications in the invention and application of the present invention, as well as in the details thereof may be realized from the teachings of the present disclosure. All such modifications as come within the scope of the following claims are considered a part or my invention I claim:

1. A compressor comprising a prime mover, a cyclically operating compressing means driven by said prime mover and adapted normally to compress a gaseous medium at each cycle of operation; means to vary the compressing capacity of said compressing means from no capacity to full capacity automatically in response to a condition 01 the gaseous medium including fluid pressure creating means eflective simultaneously with cyclical operation of said compressing means, fluid pressure operated means for eflecting the loading of said compressing means to full capacity when connected to said fluid pressure creating means, and spring means for effecting the unloading of the compressing means to no capacity when said fluid pressure operated means is disconnected from said fluidpressure creating means; and a time delay mechanism preventing the application of fluid pressure created by said fluid pressure creating means to said fluid pressure operated means until a predetermined length of time after commencement of cyclical operation of said compressing means to delay the loading of said compressing means for sufficient time to permit said prime mover to attain operating speed.

2. A compressor comprising a prime mover, a cyclically operating compressing means driven by said prime mover and adapted normally to compress a gaseous medium at each cycle of operation; means to vary the compressing capacity of said compressing means from no capacity to full capacity automatically in response to a condition of the gaseous medium including fluid pressure creating means effective simultaneously with cyclical operation of said compressing means, fluid pressure operated means for effecting the loading of said compressing means to full capacity when connected to said fluid pressure creating means, spring means for effecting the unloading of the compressing means to no capacity when said fluid pressure operated means is disconnected from said fluid pressure creating means, and a master valve between said fluid pressure creating means and said fluid pressure operated means responsive to a condition of the gaseous medium for connecting or disconnecting said fluid pressure creating means and said fluid pressureoperated means; and a time delay mechanism preventin the passage oi! fluid under pressure from said fluid pressure creating means through said master valve until a predetermined length of time after commencement of cyclical operation or said compressing means even though said master valve may be open to delay the loading of said compressing means for suflicient time to permit said prime mover to attain operating speed.

3. A compressor comprising cyclically operating compressing means adapted normally'to compress a gaseous medium at each cycle of operation; means to vary the compressing capacity or said compressing means from no capacity to full capacity automatically in response to a condition of the gaseous medium including fluid'pressure creating means eflective simultaneously with cyclical operation of said compressing means, fluid pressure operated means for eil'ecting the loading of said compressing means to full capacity when connected to said fluid pressure creating means, spring means for effecting the unloading of the compressing means to no capacity when said fluid pressure operated means is disconnected from said fluid pressure creating means, and a master valve between said fluid pressure creating means and said fluid pressure operated means responsive to a condition oi! the gaseous medium for connecting or disconnecting said fluid pressure creating means and said fluid pressure operated means; and a time delay mechanism preventing the passage of fluid under pressure through said master valve until a predetermined length of time after commencement of cyclical operation 01' said compressing means even through said master valve may be open, said time delay mechanism including a solenoid adapted to be energized upon commencement of cyclical operation of said compressing means, a switch adapted to be closed by said solenoid when energized, and a dash-pot delay mechanism causing slow action of said solenoid.

4. A compressor comprising cyclically operating compressing means adapted normally to compress a gaseous medium at each cycle of operation; means to vary the compressing capacity or said compressing means from no capacity to full .capacity automatically in response to a condition of the gaseous medium including fluid pressure creating means effective simultaneously with cyclical operation of said compressing means, fluid pressure operated means for eflecting the loading of said compressing means to full capacity when connected to said fluid pressure creating means, spring means for effecting the unloading of the compressing means to no capacity when said fluid pressure operated means is disconnected from said fluid pressure creating means, and a master valve between said fluid pressure creating means and said fluid pressure operated means responsive to a condition of the gaseous medium for connecting or disconnecting said fluid pressure creating means and said fluid pressure operated means; and a time delay mechanism preventing the passage of fluid under pressure through said master valve until a predetermined length of time after commencement of cyclical operation of said compressing means even though said master valve may be open, said time delay mechanism including a solenoid adapted to be energized upon commencement of cyclical operation of said compressing means, a switch adapted to be closed by said solenoid when energized, a

. v dash-pot delay mechanism causing slow action of said solenoid, and a solenoid'opera'ted valve between said fluid pressure creating means and said master valve adapted to be energized upon closing 01! said switch to complete the fluid connection or said fluid pressure creating means and said fluid pressure operated means.

pressure to said loading means for a predetermined length or time after-commencement of operation of said fluidpressure' creating means including a valve between said fluid pressurecreating means and said loading means and electrical means for opening said valve to permit the application of fluid pressure to said loading means, said electrical means comprising a first solenoid for opening said valve when energized,

a switch in series with said first solenoid for permitting current to flow through said first solenoid when closed, and a second solenoid for closing said switch. 7

6. A compressor comprising loading means dependent upon fluid pressure for activating power, fluid pressure creating means operated simultaneously with cyclic operation of the compressor for creating such fluid pressure, and time delay means for preventing the application of fluid pressure to said loading means for a predetermined length of time after commencement of operation of said fluid pressure creating means including a valve between said fluid pressure creating means and said loading means and electrical means for opening said valve to permit the application of fluid pressure to said loading means, said electrical means comprising a first solenoid for opening said valve when energized, a switch in series with said first solenoid for permitting current to flow through said first solenoid when closed and a second solenoid for closing said switch, said second solenoid being included in a circuit adapted to be energized fluid pressure creating means operated simulta- .neously with cyclic operation or the compressor for creating such fluid pressura'and time delay means for preventing the application of fluid pressure to said loading means fora predetermined length of time after commencement of operation of said fluid pressure creating means including a valve between said fluid pressure ore-- ating means and said loading means and electrical means for opening said valve to permit the application or fluid pressure to said loading means, said electrical-means comprising a first solenoid for opening said valve when energized, a switch in series with said first solenoid for permitting current to flow through said first solenoid when closed, a second solenoid for closing said switch, said second solenoid being included in a circuit adapted .to be energized simultaneously with commencement of cyclical operation of said compressor, and means for delaying the eflectiveness of said second solenoid to close said switch for a predetermined interval of time after becoming energized including ,a. dash-pot device.

9. A compressor comprising loading means dependent upon fluid pressure for activating power, fluid pressure creating means operated simultaneously with cyclic operation or the compressor for creating such fluid pressure, and time delay means for preventing the application or fluid pressure to said loading means for apredetermined length of time after commencement of operation of said fluid pressure creating means including a valve between said fluid pressure creating means and said loading means and electrical means for opening said valve to permit the application of fluid pressure to said loading means, said electrical means comprising a first solenoid for opening said valve when energized, a switch in series with said first solenoid for permitting current to flow through said first solenoid when closed, a secondesolenoid for closing said switch, said second solenoid being included in a circuit adapted to be energized. simultaneously with commencement of cyclical operation of said compressor, and means for delaying the efiectiveness of said second solenoid to close simultaneously with commencement of cyclical operation of said compressor.

7. A compressor comprising loading means dependent upon fluid pressure for activating power, fluid pressure creating means operated simultaneously with cyclic operation of the compressor for creating such fluid pressure, and time delay means for preventing the application of fluid pressure to said loading means for a predetermined length of time after conmiencement of operation of said fluid pressure creating means including a valve between said fluid pressure creating means and said loading means and electrical means for opening said valve to permit the application of fluid pressure to said loading means, said electrical means comprising a first solenoid for opening said valve when energized, a switch in series with said first solenoid for permitting current to flow through said first solenoid when. closed, a second solenoid for closing said switch, said second solenoid being included said swltchior a predetermined interval of time after becoming energized 8. A compressor comprising loading means dependent upon fluid pressure for activating power,

said switch for a predetermined interval of time after becoming energized including a dash-pot device; and means for substantially instantaneously unloading said compressor by removal of fluid pressure from said loading means upon cessation of cyclical operation of the compressor.

10. A compressor comprising loading means dependent upon fluid pressure for activating power, fluid pressure creating means operated simultaneously with cyclic operation-of the compressor for creating such fluid pressure, and time delay means for preventing the application of fluid pressure to said loading means for a predetermined length of time after commencement of operation of said fluid pressure creating means including a valve between said fluid pressure creating means and said loading means and electrical means for opening said valve to permit the application of fluid pressure to said loading means, said electrical means comprising a first solenoid for opening said valve when energized, a switch, in series with said first solenoid for permitting current to flow through said first solenoid when closed, a second solenoid for closing said switch, said second solenoid being included in a circuit adapted to be energized simultaneously with commencement of cyclical operation of saidcompressor, and means for delaying the effectiveness of said second solenoid to close said switch for a predetermined interval of time after becoming energized including a dash-pot device; and means for substantially instantaneously unloading said compressor by removal of fluid pres-- sure from said loading means upon cessation of cyclical operation or the compressor including a connection between said loading means and the

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