US2907348A

US2907348A - gerteis

Info

Publication number: US2907348A
Authority: US
Priority date: 1954-02-26
Filing date: 1957-08-01
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06

Description

Oct. 6, 1959 K. M. GER-reis 2,907,348 l IMPROVED VALVE MEMBER Original'FiledrFeb. 26, 1954 FIG. 2

INVENTOR. KARL M. GERTEIS AT TORNEY K 2,992,348 atented Oct. 6, i959 IMPROVED VALVE MEWER Karl M. Gerteis, Syracuse, N Y., assigner to Carrier Corporation, Syracuse, NX., a corporation of Delaware Original application February 26, 1954, Serial No. 412,793, now'latent N 2,S36,345, dated May 27, 1958. Divided and this application August 1, 1957,

Serial No. 675,648

1 Claim. (Cl. 137-622) This application is a division of my co-pending application, Serial No. 412,793, liled February 26, 1954, lno w issued as U.S. Patent 2,836,345.

This invention relates generally to reciprocating compressors and more particularly to an improved device for automatically controlling the capacity of the compressor in relation to the demand made upon the compressor. Still more particularly this invention relates to an improved valve mechanism which may be incorporated in a lluid circuit having utility in a capacity control system for a. reciprocating compressor.

The chief object of the invention is the provision of an improved control valve for use ina capacity control system fora reciprocating compressor of the kind which alternately inactivates or actiyates cylinders in the cornpresser 4and which'lincludes an unique construction preventing rapid cycling of the cylinders in response to load variations. This condition occurs when, for example, the reduction in load is sufficient to cause a cylinder to unload buty the reduced output of the compressor is insufcient to meet the reduced load requirement.

y Other objects and features of this invention willbe apparent upon a consideration ofthe ensuing specification and drawings wherein:

Figure l `i`s asectional view of the control valve illustrating the inventionj' l Figure 2 is a diagrammatic viewy illustratingV the' man? ner in which the individual elements, one of which .is'vpthe valve forming the subject ofl this invention, of an" improved capacity control-system are related'.

Briefly, the capacity .control system, in which the controlivalve forming'theinstant invention is useful, includes one or more cylinder' unloading elements, depending on the number of cylinders present, in comr'nuiiiea/tion with a common control valve having a springiurgedpis'ton movable in a passage in such manner as to permitthe application of oil pressure to certain of the unloader elements. Movement ofthe piston inthe passage is dependent upon an unbalanced force between'the spring and a source of oil, the pressure of which is'under the inluence of a regulatingV valve, which in turn is subject to the load on the compressor as evidenced bythe suction pressure to whichv the compressor is subjected. The oil under the influence of the regulating Valve is a part of the lubrication system of the compressor.V

As pointed out above, the operation of the control valve is dependent in part upon the demand upon the com-4 pressor and causes the individual cylinders to load or unload in. accordance therewith. Changes in the load upon a refrigeration system having afcornpressor equipped with a capacity control system ofthe type here described, as reected by the pressure in the suction line, tend 4to be small in comparison with the change in capacity of the compressor when, for illustration, one of two operating cylinders is unloaded. lt will be appreciated that the capacity of the compressor may be reduced b y 50% at this point. The compressor tends to balance againstl the load so that the unloaded cylinderis rapidly loaded again,

2 resulting in an action known as cycling. Rapid cycling often causes undue wear on the parts involved and should be 'avoided orat least minimized. To accomplish the elimination of rapid cycling, this invention includes an improved control valve, incorporating a ylost motion feature y,which necessitates a relatively'iarge suction pressure change before the capacity control system changes from unloading to loading or vice versa after operating through a pattern that includes either successively loading or unloading, while permitting a relatively small dilferential to occur for the purpose of functioningin the latter manner. ln other words, when the capacity control system operatesrto. change from loading to unloading o r vice versa, a relatively large dilferentialin suction pressure is neces- Isary before the changeoccurs. l

l Referring to .the attachedfdrawings, there is illustrated in Figt1're`2 a capacity controlsystem for a compressor havlin'g a plurality'of cylinders, and a crankcase. Disposedwithin the crankcase is o'ilsunip accommodating lubricant for thel operating mechanism of the compressor including a crankshaft, pistons, and connecting rods, all of whicli'are elements of alconventional compressor used, for illustration, in a refrigerationsystern which forms no essential; part ofthe invention but which, it will-be understood, are` present to form an operable compressor.

It'l will be appreciated that efficient operation of the compressor necessitates varying the output of the comaccordance with the demand made thereon. Vmethod of varying vthe output of the fjlves vequipping certain of the cylinders A er elementA as of the Ltype illustrated in Figure Z.v The unloaderxnechanis'rn, disclosed, is utilized to place the suctiony valves, not shown, of the cylinder 7; ininoperative positionand includes a lifter sleeve i lily, surrounding the cylinder, provided with an outwardly extending flange' 11. The sleeve is adapted to move in a reciprocatory manner about the outer surface `of the cylinder from a lower limit as indicatedfby band 12 ernbracing the cylinder. l i

Disposed radially about the flange 11` and in engagement with Vthe upper surface thereof are a plurality of lifter p ins livwhichoperatefto lift the suction valve from its seat in valve plate 15 in responserto the upward movement of the sleeve 170, Loading springs 16,. surround the lowerportions of the pins andrserve to maintainlthe bottomsof the pins inengagement the flange 11 on the' sleeve 16.

Movement of the sleevelllis provided by a power elelment comprising a forked leverV 17 having the end. por- 21, Anappropriate relief opening, not shown, is provided` in casing Ztl to accommodate oil which may seep between the piston and the wall of the casing. Thus, it may be seenthatl the power unloading element is so constructed and arranged as to cause the lifting pins 13 to move the suctionlvalves from their seats when there is inadequate oil pressure to overcome the action of lthe spring in the casing. "vl/hen adequate oil pressure" is supplied to the power element, the piston is forced upwardly l against the action of the spring, pivoting lever 17 to permit sleeve 1i) Vto move downwardly and'allowing springs 16`to move lifting pins 13 downward so that-the suction valves asjsume their normal position under the influence of conventio'nal positioning springs in the valveplate 15.-

lin Figure l, a control valve 28 forming the' subject of this invention isv illustrated which permits oil pressure to be introduced into the various power unloaders in a sequence depending upon the load imposed upon the compressor. Control valve 28 comprises a casing 29 having a iirst end member 30 and a second end member 31. The casing 29 is provided with a cylindrical bore 32 extending therethrough which accommodates a movable piston 33 having a head 34 and a hollow elongated shank 35, having its unattached end open, depending therefrom. Bore 32 is in communication with a socket 36 positioned within end member 30 and which is provided with a portion of reduced diameter 37, constituting a spring seat. One end of a spring member 38 is positioned against seat 37 and the other end of the spring 38 4is in engagement with the under side of the head 34 so as to normally urge piston 33 to the left of the control valve as viewed in Figure 3. Opening 38 serves to vent oil to the crankcase when the piston moves to the right, acting as an escape outlet. The piston 34 is also provided, on the shank portion proximate the unattached end, with an annular ring member 39 which in effect forms a radial projection about the shank. Mounted with the bore 32 so as to surround the shank 35 of piston 33 is a bobbin 40, having a rst enlarged end portion 41 providing a sealing engagement with the sides of the casing which dene bore 32, an intermediate portion 42 of reduced diameter and, an end portion 43, `including a sealing surface 4S', the eX- terior surface of which is formed by a series of alternately spaced grooves and ridges or

lands

44 and 45.

Casing 29 has further provided therein radial bores 46 extending from bore 32 through the side of the casing and through a boss 47 located on the external surface of the casing. A pin 48 projects through aligned openings 49- provided in the boss 47. Seated against pin 48 is a' spring member having the outer end thereof in engagement with a spherical ball 51, the parts being so designed and constructed that the balls 51 are normally urged inwardly of the casing into engagement with the grooves 44 on bobbin 40. Also positioned in casing 29 is a radial opening 53 in communication with the main supply line of the lubrication system. The casing 29 is further provided with a series of radial openings 52 through which oil from the lubrication system of the compressor passes not shown, for adjusting the size of a vent in response to the suction pressure in a compressor equipped with the capacity control system.

In order to more adequately describe my invention, the operation of the system including the valve 28 as a component thereof will be explained. When the compressor is started, the power unloader elements, because of a lack of oil pressure, are arranged with the sleeve 10 in its uppermost position and pins 13 holding the suction valves in inoperative position so that the output of the unloaded cylinders is Zero. In a relatively short period of time, the pump of the lubrication system, deriving its power from the compressor prime mover, forces oil through the lubrication system, which includes main line 1, from where it moves to the regulating valve. Oil is also delivered from the main line 1 through line 53 to the control valve 28. Due to the absence of oil in line 5S, the piston 33, together with bobbin 40, are positioned within the control valve in such a manner as to prevent passage of the oil from line 53 through any of the openings 52. The action of spring 38 moves the piston 33 to the left of the valve, as shown in Figure 3, and the annular ring 39 engages ange 41 of the bobbin, so that l the ange 41 is positioned within the opening 32 between piston must travel a distance sufficient to permit engagement between the underside of piston head 34 and the left hand end of bobbin 40. Continued movement beyond this point enables communication to be established between one pair of lines 52 and supply 53 through valve 28.

en route to the individual unloading elements mentioned s above. Cover 31 has provided therein an opening 54 for the reception of line 55 connected to the regulating valve of the system in a manner to be more completely described.

In the compressor capacity control system chosen to illustrate the control valve of this invention there is provided a regulating mechanism 56 which serves to govern the pressure of oil applied to the piston head 34 through line 55 in accordance with an operating characteristic of the compressor or machine served by the capacity control system. It will be understood that the pressure of the oil flowing in line 55, as determined by the operation of the regulating mechanism 56 bears a direct relation to the position of piston 33 in control valve 28 thus determining the number of lines 52 in communication with main oil supply line 53.

The regulating mechanism 56 is not a part of this invention. Accordingly only a brief description of it will be necessary to appreciate the system illustrated to describe control valve 28. Regulating mechanism similar to member 56 is described in detail in United States Patents 2,626,099, and 2,836,345, as Well as co-pending application, Serial Number 675,726, iiled August l, 1957, in the name of Karl M. Gerteis and assigned to the assignee of this invention.

The regulating mechanism serves to vary the pressure applied to the piston 33 through line 55 by venting a portion of the main oil supply delivered to the regulating mechanism 56 through branch line 85. The amount of oil so vented is in direct relation to a variable characteristic of the machine served by the capacity control system. Thus regulating mechanism 56 is provided with means,

At least two of the cylinders in the compressor are activated. If the pumping capacity of the machine, under these circumstances, satisfies the demand on the machine as indicated by the suction pressure in the machine, control valve 28 permits the capacity control system to maintain the arrangement described. In the event the suction pressure in the machine drops indicating a reduced pumping capacity requirement, the novel control valve automatically operates through the lost motion feature to be described, to inactivate the unloaders being served by the lines 52 previously placed in communication with supply line S3. It accomplishes this as the pressure in line 55 drops as a result of the condition sensed by the regulating mechanism 56. In other words, regulating mechanism 56 vents an amount of oil flowing through it so that the line pressure in line 55 drops. Spring 38 in control valve 28 forces the piston 33 to the left as viewed in Figure 1. With the arrangement shown, a lost motion action sufficient to eiect delay of movement of bobbin 40 occurs for the reason it is necessary that piston 33 travel a distance to the left, under the action of spring 38, suiicient to eifect engagement of bobbin 40 by annular ring 39. Then in the event the machine demand changes rapidly, movement of the valves by the lifter pins 13 is avoided and the condition known as chattering substantially eliminated.

I claim:

In valve mechanism for controlling flow of tluid from a main supply line to one or more service lines wherein operation of the Valve is responsive to the action of a fluid source subject to pressure variations, the combination comprising a casing having a chamber therein, a first opening for flow of the fluid subject to pressure variations into the chamber, a second opening for connecting the fluid supply line to the chamber and a plurality of ports serving to place the supply line in communication, through the chamber with the service lines; a piston slidably mounted in said casing, said piston having a head portion and a shank portion depending therefrom and spaced from the sides of the casing defining the chamber; resilient means urging the piston to a predetermined position within said casing chamber opposing action of the fluid under pressure variations; a ring member xedly secured to and surrounding the shank portion of the piston at the end thereof remote from the head portion; and an annular member having enlarged end portions in engagement with the wall of the casing surrounding the shank portion of the piston but of a lesser axial length so that movement of the piston within the chamber in response to unbalanced forces between the resilient means and the fluid subject to pressure variations causes ber secured to the shank portion of the piston to vary the number of ports in the casing in communication with 5 the fluid supply line.

References Cited in the file of this patent UNETED STATES PATENTS 1,954,442 Dall et al. Apr. 10, 1934 10 2,568,528 Welte Sept. 18, 1951 FOREIGN PATENTS 865,154 France Feb. 17, 1941 495,402 Canada Aug. 18, 1953