US2208428A - Apparatus for controlling compressor capacity - Google Patents

Description

July 16, 1940. c, E, I OL 'T 2,208,428

APPARATUS FOR CONTROLLING COMPRESSOR CAPACITY Filed June 4,1938 2 Sheets-Sheet 1 rial. Q8 fifhfl 22 2 ,22 22 f5 21 Q 25 INVENTOR CbnsianilY/Yzbolet ATTORNEY y 16. 1 c. E. moLa-r 2,208,428

' APPARATUS FOR CONTROLLING COMPRESSOR CAPACITY Filed June 4, 1938 2 Sheets-Sheet 2 INVENTOR 0012822222271 jy g BY Si ATTIORNEY I Patented July 16, 1940 UNITED STATES PATENT OFFICE APPARATUS FOR CONTROLLING COMPRESSOR CAPACITY Constant E. Nicolet, Syracuse, N. Y., assignor to Carrier Corporation, Syracuse, N. Y., a corporation of Delaware Application June 4, 1938, Serial No. 211,755

12 Claims.

This invention relates to fluid compressors, and more particularly to compressors used in conjunction with refrigerating systems.

The general object of the invention is to pro-- a system of compressor capacity control which is simple, inexpensive and reliable and which results in eflicient operating conditions regardless of whether the compressor is operated at full .or partial loajd.

A feature of the invention resides in maintaining constant communication between the suction g4 v line serving the compressor and one or more of the cylinders or compressing elements jthereof whenever the pressure in the suction line falls below a predetermined point. The reduction of pressure obtaining in the suction line of a com- 95 pressor serving a refrigerating system indicates a reduction in the load upon the compressor, and

under such conditions all of the required compressing action might be provided, for example, by a lesser number of cylinders than the total '30 number with which the compressors is provided. A feature of the invention, therefore, resides in constantly maintaining in open position the suction valves serving one or more compressing elements of a compressor apparatus whenever the suction pressure or, in other words, the load Y on the compressor apparatus, falls below a predetermined point.

Another feature of the invention resides in providing an automatically operative pressure o responsive control element, subjected to the suction pressure, for fixedly maintaining the suction valve mechanism serving one or more compressor elements in open position whenever the suction pressure falls below apredetermined point, while 5 permitting said suction valve mechanism to operate in normal manner whenever the suction pressure exceeds said point.

Those compressor elements whose suction valve mechanisms are maintained open are, in

50 effect, cut out of active compressing service, for

the gas displaced by such elements is merely pumped back to the suction line and, by reason of the fact that no substantial increase in pressure is provided for by operation of the compres- 65 sing elements under such conditions, no fluid is discharged from the compressing elements into .the normal high pressure discharge line of the compressor. The 'compressor elements which are thus cut out of active compression service require a power input sufiicient only to overcome 6' friction losses. Accordingly, the power consumption of the entire apparatus varies very nearly in proportion to the number of cylinders functioning in the normal manner. Thus, for example, if one cylinder of a two-cylinder com- 10 pressor is cut out of service (that is, if fluid from one cylinder is re-supplied from the cylinder back to the suction line upon what would normally be the compression stroke), the power necessary to drive the compressor would approximate onehalf of the power required when both of the cylinders are operating in the normal manner.

Other objects, features and advantages of the invention will be more apparent from the following description to be read in connection with the accompanying drawings in which:

Fig. 1 represents a fragmentary view partly in section of a compressor apparatus embodying one form of the invention;

Fig. 2 is a fragmentary elevational view illustrating a portion of the valve control mechanism of Fig. 1 in operative position;

Fig. 3 is a view in perspective of a yoke em- .ployed for operating the valve-lifting assemblies;

Fig. 4 is a view in perspective of one of the valve-lifting assemblies;

Fig. 5 is a view taken on the line 5-5 of Fig. 1; and

Fig. 6 is a view, partly in section, and similar to Fig. 1, illustrating a modified form of the invention.

Referring now to the drawings, numeral ill designates generally a compressor having a crankcase ii, and a suction manifold l2, adapted to receivefluid to be compressed through any suitable opening (not shown) from, for example, the evaporator of a refrigerating system of which the compressor Ill comprises a part. Numerall3 designates a discharge manifold into which compressed fluid is discharged from the cylinders of the compressor. While only one cylinder It, provided with a piston l 5, is shown, it is to be understood that any number of cylinders may be utilized without departing from the scope of the invention, and that generally the invention is utilized in connection with compressor apparatus comprising two or more compressing ele- In a manner well understood in the art, each cylinder I4 is connected with suction manifold l2 through one or more passages l8 communicating with annular chamber l9. Flow of fluid from chamber l9 into the cylinders is controlled by annular disc valve 20 adapted, when closed, to be seated upon valve seats 2! formed at the upper extremities of the chamber Id. In a manner well understood, a recess 22 is formed in the valve guide member 23 to provide for communication between chamber l9 and the cylinder interior, and to guide the valve 20 in its reciprocating motion. Guide member 23 is provided with a plurality of discharge outlets 26, the flow through which outlets is controlled by annular disc valve 25, which is adapted to reciprocatingly move within valve guide member 25. Passages 21 and 28 provide for flow of compressed gasfrom the valve 25 to the discharge manifold it.

It will be noted that the suction valve 2B is concentric with and is of greater diameter than the cylinder I l.

Formed within the casing of the compressor l0 and subject to the suction pressure obtaining in suction manifold i2 is an expansible bellows 29 contained within a casing 36 which is preferably apertured, as indicated at 3i, to provide communication between the interior of the casing 30 and the suction manifold i2. Within the expansible bellows 29, the interior of which is sealed from the suction chamber i2; there is positioned a spring 32 which tends to elongate the bellows and thus to force the element 33, carried at the right and free end of the bellows 29, toward the right, as seen in Fig. 1. If desired, the interior of the bellows may be provided with an auxiliary spring 34. The springs 32 and 343 may be adjusted by turning screw which bears against collar 36, against which the springs 32 and 3d are positioned. If desired, a cap 31 may be provided for covering the end of screw 35.

The springs 32 and 3d, and the bellows 29 within which they are contained, are so designed that when the pressure in manifold i2 is at or exceeds a predetermined point, the bellows 29 will be in relatively compressed condition; but when the pressure in the chamber i2 drops below this predetermined point, the combined pressures of the springs will serve to elongate the bellows, thus to move member 33 to the right. The cylinder I is provided with a pin 38 which extends through an aperture 39 formed in a yoke which extends halfway about the cylinder Hi, the yoke being slidable upon pin 38. A stud M extending from the member 33 is fitted within aperture 62 of yoke M and is provided with a collar 53 adapted to engage the yoke.

Pivoted at the side of cylinder M, as at M, is an arm 65 which is pivotally connectedby pin or the like 46 to a second arm All. Thus arms t5 and 41 comprise a toggle joint. Arm till pivotally engages a member 88, approximately arcuate in shape, as by a pin or the like, 69, adapted to extend within the aperture 50 formed in the member 48. Member 88 carries a pair of upwardly extending pins 5| which extend through suitable apertures 5la formed in the member 52 in which inlet passages l8 are formed. Preferably, a member 48 with its pins 5i is provided at each side of the cylinder it. It will be apparent, of course, that more than two such members 68 may be used, if desired, and that any number of-pins I corresponding to pins 5i may be used without de- It is J aaoaaas ferentially spaced, since this assures level lifting of the valve 28.

Upon a decrease in the pressure obtaining in suction manifold l2 below a predetermined point, the bellows 29 will expand and the member 33 will abut the yoke 41! and move it to the right; This in turn will cause clockwise rotation of the arm 65 about the pin M and the counterclockwise rotation of the arm fill. Such rotation of the arms 65 and M constitutes a toggle-joint action which serves to raise the members 48 and the pins 5| mounted thereon, so that the suction valve 20 is raised by the pins 5!, as shown in Fig. 2. So long as the valve 2t remains in raised position, compression within the cylinder it served thereby cannot be accomplished, since upon what would normally be the compression stroke, the gas which has been intaken within the cylinder is merely discharged back into the suction manifold B2.

Whenever the suction pressure in manifold l2 rises sufiiciently to recompress the bellows 29, the arms 416 and 61 will return to the position indicated in Fig. 1 thus to lower the members dB and to effect release of the valve 20 from the control of pins 5 i and normal operation of the valve 20 will thereafter continue.

- To provide for snap action of the lift pins hi, there is preferably provided an arched spring 53 pivotally connected to the side of the cylinder It, as at 56. The other end of the spring 53 is pivotally connected at 55 to a crank arm extension 56 of arm 35. As will be apparent from inspection of'Figs. 1 and 2, whenever the pins 5! are in the position of maximum lift, the pivot point 5'? at which the yoke is connected to arm $5 is off-center and to the right of a line connecting the centersof pins M, M and d9. When the bellows 29 is compressed as the pressure in suction manifold l2 increases, the member 33 and hence the pivot point 51 are moved relatively slowly to the left and then, under the influence of spring 53, pivot point 51 is snapped rapidly to the left, the snap action being permitted by the travel of yoke M to the left along the stud M of member 33. The snap action thus provided quickly and efiectively lowers the pins 5| and thus restores the valve 29 to normal operating condition. The spring 53 also facilitates the lifting of the valve id in a corresponding manner.

In Fig. 6 is illustrated a modification of the invention in which gas to be compressed is supplied from suction manifold l2a to suction passages |2b and thence to the cylinders, the compressed gas being delivered to discharge manifold lfla under the control of valve 250. The bellowsoperated stud til carries a yoke 58 from which depend a plurality of pins 59 extending through the suction passages I21; and adapted, when the yoke 58 is in maximum downward position, to hold the suction valve 20a in downward or open position. When the pressure in suction manifold I2a. increases, the bellows is compressed'and the yoke 58 is lifted by the 'collar, 43, thus freeing the valve 20a to operate in normal manner. h

If desired, different numbers of cylinders of a I compressor may be arranged /to cut out at different suction pressures by suitable adjustment of the mdividual bellows control devices associated therewith. Further, if so desired, a single bellows device, such as illustrated in Fig. 1, may be utilized to control the suction valves of two or more cylinders merely by, sufflciently increasing the length of the yoke Ml.

particular reference to a compressor of the reciprocating type, it wil1 be apparent that the invention is not so limited but may be utilized in connection with various types of compressor apparatus. Further, while as above described it is contemplated that the cylinder it constitutes one compressing element of a compressor embodying a plurality of compressing elements, it is to be understood that, if desired, the invention may be utilized in connection with compressor apparatus having but a single compressing element, or for cutting out oi service all of the compressing elements of a multi-compressing element apparatus. Thus interruption of compression action may be eiIected without stopping and starting of the compressor driving means.

Since many changes may be made in the invention without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not in a limiting sense, applicant limiting himself only as indicated in the appended claims.

I claim:

1. In a fluid compressor apparatusincluding a first compressing element; a second compressing element connected in parallel fluid flow ar rangement with said first element, driving means for said elements, fluid supply means and. a suction valve for controlling the communication between said fluid supply means and said first compressing element, the combination of a pressureresponsive element subjected to the pressureof said fluid supply means, and means under the element connected in parallel fluid flow arrangement with said first element, driving means for said elements, fluid supply means and a suction fluid pressure in said supply means falls below apredetermined point.

3. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compressing element, the combination of an expansible and contractable element subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, means adapted constantly to maintain said valve in opened position, and means for rendering operative said last-mentioned means responsive to the expansion .of said expansible element and for rendering inoperative said last-mentioned means responsive to thecontraction of said element.

4. In a fluid compressor apparatus including a compressing element, driving means therefor,

fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compre'ssingelement, the combination of an expansible element subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of the pressure at which said expansible element will expand.

5. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted while the other end of said bellows is free to move, means adapted to maintain said valve in opened position, and means responsive to movement of the free end of said bellows upon expansion of said bellows for rendering operative said lastmentioned means, said last-mentioned means being arranged to become inoperative upon contraction of said bellows.

6. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted while the other end of said bellows is free to move, means adapted to maintain said valve in opened position, means responsive to movement of the free end of said bellows responsive to expansion of said bellows for rendering operative said lastmentioned means, said last-mentioned means being arranged to become inoperative upon con.- traction of said bellows, spring means within said bellows tending to expand said bellows, and means for adjusting the force exerted by said spring means, so that by adjustment of said spring meanssaid bellows may be caused to expand at difi'erent predetermined fluid pressures in said fluid supply means.

7. In a fluid compressor apparatus including a compressing element. driving means; therefor, fluid supply means and a suction valve ior controlling the communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fiuidpressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows beig fixedly mounted .while the other end of said bellows is free to move, means adapted to maintain said valve in opened position upon expansion of said bellows, said means including a toggle joint and valve-controlling means actuated by said toggle joint, and

a yoke actuated by the free end of said bellows and pivotally connected to said toggle joint.

8. In a fluid compressor apparatus including a compressing element, driving means therefor,

fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compressing element, the combination'of an expansible bellows subjected to the fluid pressure obtaining in said supply. means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted and the other end of said bellows being free to move, meansadapted to maintain said valve in opened position upon expansion of said bellows to a predetermined degree, said means including a pair of toggle joints and valve-controlling elements actuated by said toggle joints, a yoke actuated by the free end of said bellows and pivotally connected to said toggle joints, and spring means for providing snap-action operation of said toggle joints, said yoke being slidably positioned upon an extension of the free end of said bellows.

9. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling the communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted and the other end of said bellows being free to move, means adapted to maintain said valve in opened position upon expansion of said bellows to a predetermined degree, and means responsive to movement of the free end of said bellows for rendering operative said last-mentioned means, said last-mentioned means including a yoke actuated in response to expansion of said bellows, and a plurality of pins actuated by said yoke and adapted to engage said valve and to maintain said valve in opened position when said bellows is expanded.

10. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted and the other end of said bellows being free to move, a pair of toggle joints arranged on opposite sides of said compressing element, valve-engaging mechanism actuated by said toggle joints and adapted to engage and open said valve responsive to elongation of said toggle joints, and a yoke actuated by the free end of said bellows and adapted to elongate said toggle joints upon expansion of said bellows.

11. In a fluid compressor apparatus including a compressing element, driving means therefor, fluid supply means and a suction valve for controlling communication between said fluid supply means and said compressing element, the combination of an expansible bellows subjected to the fluid pressure obtaining in said supply means and adapted to expand upon reduction of said pressure below a predetermined point, one end of said bellows being fixedly mounted and the other end of said bellows being free to move, a pair of toggle joints-arranged on opposite sides of said compressing element, valve-engaging mechanism actuated by said toggle joints and adapted to engage and open said valve responsive to elongation of said toggle joints, and a yoke actuated by the free end of said bellows and adapted to elongate said togglejoints upon expansion of said bellows, said valve-engaging mechanism comprising a pair of secondary yokes each actuated by one of said toggle joints, and a plurality of valve-engaging pins operated by said secondary yokes.

12. In combination, a plurality of compressor elements, feed means for supplying fluid to be compressed to said elements in parallel fluid flow arrangement, means arranged in parallel fluid flow arrangement for receiving compressed fluid from said elements, inlet valve means controlling communication between said feed means and at least one of said compressor elements,'and means responsive to decrease of the pressure in said feed means below a predetermined point for maintaining said valve means in continuously opened position, said last-mentioned means including a pressure-responsive element subject to the pressure prevailing in said feed means, and valve actuating means under the control of said control element.

CONSTANT E. NICOLET.

DISCLAIMER 2,208,428.Oonstant E. Nicolet, Syracuse, N. Y. APPARATUS FOR Cm rRoLLmG COMPRESSOR CAPACITY. Patent dated July 16, 194p. D1scla1mer filed December 11, 1941, by the assignee, Carrier Corporation. Hereby enters this disclaimer to claims 1 and 12 of said patent.

[Ofiicial Gazette January 6, 1.942.]

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