US3144982A - Compressor unloading means - Google Patents

Description

Aug. 18, 1964 E T. NEUBAUER ETAL 3,

COMPRESSOR UNLOADING MEANS Filed Oct. 30, 1961 4 Sheets-Sheet 1 I; A y; ya /a 1% w Aug. 18, 1964 Filed Oct. 30, 1961 E. T. NEUBAUER ETAL' COMPRESSOR UNLOADING MEANS 4 Sheets-Sheet 2 I VENTORIS.

57127 77/1/19 42/62 Zysae77j? 607776700X yr W/vEJ s Aug. 18, 1964 E. ,T. NEUBAUER ETAL 3,144,932

COMPRESSOR UNLOADING MEANS Filed Oct. 30, 1961 4 Sheets-Sheet 3 1964 E. T. NEUBAUER ETAL 3,144,982

COMPRESSOR UNLOADING MEANS Filed Oct. 30, 1961 4 Sheets-Sheet 4 United States Patent 3,144,982 QUMPRESSUR UNIJQADHNG MEANS Emil ll. Neubauer and Russell E. Cornstoelr, Sidney, @hio, assignors to Copeiand Refrigeration Eon-partition, Sidney, Ohio, a corporation of Michigan Filed @ct. Fall, 1961, Ser. No. 148,488 11 Claim. (Q'l. Bil-(iii) This invention relates in general to improvements in gas compressor cylinder unloader actuators and particularly concerns a lever type of actuator for moving compressor unloader lift rings and lift pins to and from their unloading positions.

The use of compressor unloaders is desirable in obviating the need for the extremely high drive torque which would be required from the prime mover of the compressor in starting the compressor into operation if all of the suction valves could close to thereby place the compressor under full load. These unloaders are also employed to control compressor capacity according to variations in refrigeration load requirements. As is conventional, the compressor suction or intake pressure and/ or the temperatures at various portions of the refrigeration system may be utilized to inform the oil pressure source for the unloaders when and to what extent the suction valves of additional cylinders are to be closed for further loading the compressor. In applicants preferred form of the invention, suificient lubricating oil pressure is gradually built up by the compressor to load the cylinders. It is noted that applicants unloader actuator may also be used to unload rather than load the cylinders as oil pressure is built up.

As is also conventional, a master cylinder may be used as a hydraulic fluid supply control for the hydraulic cylinders of each of the unloading devices by progressively supplying hydraulic fluid to each of the cylinders as the suction pressure of the compressor rises as a result of increasing refrigeration load. As noted above, other operating parameters of the system may also be used to control the actuators. It is seen that at starting, all or any desired number of cylinders will be unloaded, and as the oil pressure steadily increases with increasing compressor speed, the number of cylinders depending on load requirements that may be loaded, will increase.

It is particularly noted that applicants invention is not to be limited by reference to any particular type of master cylinder, control valve, or sensing device for regulating the flow of oil to the actuator and it is emphasized that applicants actuator finds uitility so long as there is some source of actuating fluid therefor.

The present actuator is characterized by a significant reduction in parts and complexity relative to conventional compressor unloader actuators, without loss of any emciency or utility for the unloading function. Moreover, applicants actuator is so constructed as to materially reduce the time required for the loading or unloading operations, and also to reduce suction valve and unloader actuator noise during the transition between unloading and loading of the cylinders.

In order to emphasize the relative structural simplicity of the present actuator, and its utility, it is noted that conventional unloader actuators are comprised of numerous springs and a relatively large hydraulic cylinder and seals which are readily susceptible to wear. Applicants device,

however, consists essentially of only two springs, a supporting bracket, a lever pivotally mounted on the bracket, and a single hydraulically operated cylinder and seal of greatly reduced size for pivoting said lever.

It is a principal object, therefore, of this invention to provide an unloader actuator of simple and rugged construction which is fast acting, is comprised of a minimum number of moving parts, is readily adapted for installation on conventional compressors, is quiet in its operation, and requires a relatively small volume of oil for actuation of its hydraulic cylinder.

Another object is to provide a pivotal lever type of unloader actuator With spring means for supplying the unloading force, and hydraulic cylinder means for counteracting the force of said spring means when loading of the cylinders is desired, wherein the spring means and cylinder are so positioned relative to the pivotal axis of the lever portion of the actuator that hammering: of the pivotal bearings of said lever portion is prevented.

A further object is to provide a structurally simple and relatively low cost unloader actuator having increased speed of operation and reliability of performance due in part to the reduction in size of the hydraulic cylinder and ring seal.

A further object is to provide a novel nested arrangement of a plurality of applicants compressor unloader actuators on a cylinder bank whereby the space required for said actuators is at a minimum.

Further objects and advantages of the present invention will become apparent from the following description and drawings in which:

FIGURE 1 shows a partially broken away plan view of a compressor cylinder and unloading device incorporating applicants actuator mounted on the compressor hous- FIGURE 2 represents a partially broken away side view of FIGURE 1 with the cylinder loaded;

FIGURE 3 shows a partially broken away side view of FIGURE 1 with the cylinder unloaded;

FIGURE 4 represents a cross sectional view of FIG- URE 2 taken along the line 4-4 thereof in the direction of the arrows with piston and connecting rod omitted;

FIGURE 5 is a diagrammatic view of a compressor unloader and a hydraulic circuit therefor; and

FIGURE 6 is a developed view of a compressor cylinder and unloader arrangement for a multi-bank radial compressor showing the cylinder banks thereof as lying in one plane for discussion purposes.

Referring to the drawings, a compressor housing ltl has frictionally secured therein a cylinder 12 to which is secured a suction valve plate 14 by bolts 16. The valve plate M is provided with an annular recess 18 and a plurality of recesses 2i? within recess 18 for receiving a plurality of springs 22 which urge an annular suction valve disc 24 toward a number of suction ports 26 spaced around the flange 2% of the upper part of the cylinder liner l2. Recess in acts as a gas cushion for valve disc 24 and prevents it from striking valve plate M with. any significant force during the suction stroke of the piston. Positioned on the top surface of the plate 14 is the discharge valve cage 3d having an annular recess 32 lined with a plastic cushion 3 held in by retaining ring 35 and having a plurality of recesses 36 therein receiving springs 38 which urge discharge valve disc d ll toward the discharge port comprising the annular lands 42 and 44. A plurality of spaced discharge passages 4-6 and 4-8 are provided in cage 30 and communicate with the discharge manifold through chamber 54 of cylinder head 52. In chamber 59 is provided a safety head spring 54- which resiliently urges valve cage 39 against the valve plate 1 so that pressure developed within cylinder 12 by slugging would not tend to become sufficiently high as to damage valves and other parts.

The lifting structure for engaging and maintaining suction valve disc 24 away from its annular seat lands 25 and 27 comprises a plurality of lift pins 56 reciprocably mounted in a plurality of apertures 58 circumferentialiy spaced in flange 28 of cylinder liner 12. Lift pins 56 circumferentially spaced and engaged by flange :54 of a lift ring 66 slidably mounted on the outside of the cylinder 12, are provided with shoulders 69 against which abut springs 62 for urging the pins downwardly.

Applicants actuator generally indicated at 67 comprises a U-shaped bracket 63 secured to compressor housing It? by bolts '70 and is provided with a pair of upstanding lugs 72 positioned at spaced points around the cylinder 12. Integrally formed with the bracket 68 is a hydraulic cylinder 74 having a fluid inlet 76 connected to a fluid conduit 78. Slidably mounted in this cylinder is a piston 84 having an O-ring or other type of ring shaped seal 82 mounted in a groove 84 and movable with the piston. The underside of piston 84 is provided with a recess 86 to allow the incoming fluid to initially get under practically the entire bottom of the piston, and under the entire bottom when the piston begins to move upwardly in cylinder 74-. Lugs 72 are provided with aligned apertures 88 threaded for receiving bolts 90 having bearing portions 92 rotatably mounted in legs 94 of the lifting lever or lift arm 96. Lever 96 is provided with a portion 93 which bears against the top of the piston and is resiliently urged thereagainst by a pair of springs 99 hooked through apertures 100 in lever 96 and attached to lugs 102 formed on bracket 68.

Referring to FIGURE 5, the fluid inlets '76 of each of applicants unloader actuators is shown to be connected to the compressor oil pump 1% through three-way valves 110 operatively connected to solenoids 112. These solenoids may be electrically connected to pressure-sensitive electrical switching means and/or temperature-sensitive electrical switching means strategically located in various places within the refrigeration system so that as certain refrigerant gas pressures and/ or temperatures occur within the system, the compressor cylinders will be loaded or unloaded according to a predetermined plan. The pump outlet is connected to each valve 110 through branched feed line 114, and the pump inlet or oil sump 1116 is connected to the exhaust port of each of these valves through return line 118.

In the operation of applicants unloading device, it is seen that when no or little oil pressure is being transmitted to hydraulic cylinder 74, springs 99 will pivot lever 96 around bolts 90 and engage abutments lltid of legs 94 with the underside of flange 64 of ring 66. The springs 62 are thereby compressed and pins 56 move upwardly to engage valve disc 24 and move it off of its seats 25 and 27. In this position of the suction valve 2d, the compressor gas which is drawn into the cylinder 12 and compressed by piston 106 is forced back out through the suction ports 26 rather than out through the discharge ports 46 and 48 since discharge valve 4t is forced against its seat shoulders i2 and 44 by springs 38. By this operation of the unloading device, the prime mover of the compressor is allowed to start the operation of the compressor without excessive output torque, and also the capacity of the compressor is regulated by preventing the compressor from pumping excessive refrigerant gas. When the compressor attains operational speed and it is desired to pump refrigerant, each of the valves 110 upon actuation by their separate solenoids 112 will allow the trans mission of pressurized fluid to cylinders 74 as required for the proper compressor capacity. This fluid causes piston 84 of each actuator to move upwardly and rotate its associated lever 96 against the force of springs 99 to move the abutments 10 i downwardly and allow springs 62 and 22 to move suction valves 24, pins 56 and ring 66 downwardly to thereby load the cylinder for the required increase in refrigerant flow through the system.

It is noted that during the time interval that cylinder 74 is becoming filled with or emptied of oil, the piston 1% makes several reciprocations within its cylinder 12. Also during this time, pins 56 are projected beyond the seat lands 25 and 27 and the alternate suction and compression strokes of piston 196 causes the suction valve disc 24 to be alternately pulled against its upper cushion 18 by the gas flow through ports 26 and driven against the pins 5 by the springs 22. If this time interval is substantial, the hammering of disc 24- against pins 56 will cause considerable noise and may result in damage to the pins and the valve disc, Since applicants actuator cylinder 74 is of a relatively small volume, it can be rapidly filled with and emptied of oil, with the result that the aforesaid time interval is substantially shortened as compared to that of conventional unloader actuators. Moreover, the reduced size of ring seal 82 reduces the frictional resistance of the cylinder '74- which further enhances its speed of operation.

Another aspect of the hammering of disc 24 against pins 56 is that the hammering force is transferred to the ring 66 and hence to the ends 94 of the lever 96 which results in hammering of ends 94 against their supporting shafts 92. It was discovered that by placing springs 99 intermediate the shafts 92 and the lever portion 98, the lever ends 94 would be in continuous engagement with the top portions of shafts 92 and would have no chance to hammer thereagainst.

In FIGURE 6 is shown a layout of a plurality of cylinder banks A, B, C, and D which are the banks of a radialtype compressor. The eccentric or crankshaft axis E of the radial compressor is in actual construction equidistantly spaced from the cylinder banks. The banks are shown in a single plane in FIGURE 6 merely to indicate the positioning of the unloader actuators with respect to the cylinders of each bank, the piston connecting rods of the banks being spaced axially along the crankshaft E. It is seen from FIGURE 6 that the unloader actuators generally indicated 67 are positioned inwardly of the edges 129 of each of the cylinder banks and the hydraulic cylinders 74 thereof extend generally toward the adjacent cylinders where they are positioned adjacent to the unloader actuators associated with said adjacent cylinders. By so nesting the hydraulic cylinders or servomotors 74, it is not necessary to extend the width of the cylinder banks or to space them further apart in order to prevent interference of the actuators with the adjacent cylinder banks and heads hereof. It is noted that if one should desire to use any other multicylinder arrangement, the unloader actuator portions comprising the unloader cylinders or servomotors 74 and connecting lever portions 96 could in an analogous manner he nested partially or entirely within the space between adjacent cylinders.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modifications, variation and change without departing from the proper scope or fair meaning of the subjoined claim.

What is claimed is:

In an unloading device for engaging the ring-shaped suction valve of a gas compressor, a plurality of lift pins reciprocably mounted on said compressor at spaced intervals around the cylinder associated with said valve, reciprocable support means for supporting and moving said pins substantially simultaneously into lifting engagement with said valve, a substantially U-shaped lever having legs intermediate portions of which are pivotally mounted on said compressor at spaced points around said cylinder,

abutments at the outer ends of said legs engageable with spaced sportions of said support means for urging it and said pins toward said valve, hydraulic power means engaging the central portion of said lever in a direction urging said abutments away from said support means, and spring means connected to said legs between said central lever portion and said intermediate leg portions, said spring means constantly urging said lever in the opposite direction from that of said power means engagement, whereby said spring means will continuously urge said intermediate leg portions in one direction against their pivots.

References Cited in the file of this patent UNITED STATES PATENTS Nicolet July 16, 1940 Gerteis May 27, 1958 Hanson et a1 Dec. 15, 1959 Nicholas Oct. 18, 1960 Villadsen Dec. 13, 1960

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