US3578883A - Unloader for multicylinder refrigeration compressors - Google Patents

Abstract

Means are disclosed for controlling the output and reducing the driving load of a multicylinder refrigeration compressor comprising valve means for closing off the inlet to one or more cylinders motivated by the fluid pressure discharge of the compressor and controlled by a solenoid-operated servo valve.

Description

. I United States Patent [72] Inventor Lawrence W. Cheney Sidney, Ohio May 14, 1969 May 18, 1971 Copeland Refrigeration Corporation [21 1 Appl. No. [22] Filed [45] Patented [73] Assignee [54] UNLOADER FOR MULTICYLINDER REFRIGERATION COMPRESSORS 3 Claims, 2 Drawing Figs.

[52] US. Cl 417/286, 417/278, 417/295 [51] Int. Cl F0411 49/00 [50] Field of Search 230/30, 31, 28, 22, 29, 27; 417/278, 286, 295

[56] References Cited UNITED STATES PATENTS 1,806,925 5/1931 Trapper 2,160,860 6/1939 Gustafson 2,256,565 9/1941 Mantle 2,961,148 11/1960 Courtney, Jr... 3,119,550 1/1964 West et a1. 3,303,988 2/1967 Weatherhead 3,406,897 10/1968 Diels Primary Examiner-Mark M. Newman Assistant Examiner-John J. Vrablik AttorneyHarness, Dickey & Pierce ABSTRACT: Means are disclosed for controlling the output and reducing the driving load of a multicylinder refrigeration compressor comprising valve means for closing off the inlet to one or more cylinders motivated by the fluid pressure discharge of the compressor and controlled by a solenoidoperated servo valve.

1 UN LOADER FOR MULTICYLINDER REFRIGERATION COMPRESSORS BACKGROUND OF THE INVENTION Although various types of unloading and capacity control apparatus have been employed heretofore in connection with refrigeration compressors, all such systems commercially used heretofore have been subject to certain drawbacks. Some have operated satisfactorily but have required a substantial injury during shipment and to possible accidental damage after installation, while the field labor required in connection with the installation and maintenance of such external systems is subject to errors which created problems in actual operation, and such field labor costs are high in any event. An important object of the present invention is therefor to provide an improved system which is installed during manufacture, and all of the major components of which are internal with the exception of a single component which is the only element apt to require servicing during the expectable life of the compressor and which is so constructed and installed that while accessible for service, the danger of accidental damage thereto is insignificant.

Another object of the invention is to provide such a system which although powered by discharge gas pressure is not sensitive to variations in such pressure, does not involve throttling of the inlet gas, and does not cause overheating.

Other objects and advantages will become apparent on consideration of the present disclosure in its entirety.

BRIEF DESCRIPTION OF THE FIGURES OF DRAWING FIG. 1 is a fragmentary partly sectional end elevational view of a three-bank radial reciprocating compressor incorporating the present invention and FIG. 2 is a cross section taken substantially on line "-11 of FIG. 1, and looking in the direction of the arrows.

DETAILED DESCRIPTION OF PREFERRED FORM OF THE INVENTION Reference character 10 designates generally the body or cylinder block portion of a multicylinder refrigeration compressor shown as having three banks respectively designated ll, 12 and 13. Although only two cylinders are illustrated, comprising cylinder 15 in bank 12 and cylinder 16 in bank 13, it will be recognized that each bank may contain one, two or more cylinders and that the construction illustrated typifies known commercial practice and is merely illustrative insofar as the compressor itself is concerned. The inlet (not shown) to the compressor is in open communication with all of the riser passages as l8, 19 leading to the cylinders in each bank. Similarly, all of the discharge chambers as 21, 22 of the cylinders in the several banks are in open communication with the outlet (not shown) of the compressor.

Suction chambers 23, 24 in each bank communicate only with the inlet ports of the cylinders of their respective banks, each suction chamber receiving refrigerant from its individual riser passage as 18 or 19. In the illustrative embodiment depicted, only bank 12 is equipped with unloading means. The inlet port 26 in valve plate 27 communicates via inlet valve means 28 with cylinder 15, while the outlet port 31 in the valve plate leads from the cylinder 15 via outlet valve means 32 to discharge chamber 21.

Communication between inlet passage 18 and suction chamber 23 is controlled by a valve 35 slidable in the cylinder head 36, biased open by spring means 37, and movable to and from sealing engagement with inlet passage 20 in the valve plate. The upper portion of the valve is shaped to define a piston portion 38 slidable in a servo cylinder 39 formed in the head and acting to guide the valve.

Cylinder 39 is connected via communicating passageways 41, 42 with a valve chamber 43 in a solenoid valve body 40 attached to the top of the cylinder head 36. Valve chamber 43 contains a shuttle valve ball 44 shiftable axially in the body 40 amount of external tubing and apparatus which is subject to to alternatively connect either the suction chamber 23 or discharge chamber 21 to servo cylinder 39. The valve ball is located by a combined seat and cage ring 45 and movable between a down position seated on ring 45 in which it blocks communication between chamber 43 and discharge chamber 21 and an up position in which it is seated against an upper coaxially disposed seat ring 46 and blocks communication between chamber 43 and suction chamber 23. When the ball 44 is in the down position, chamber 43 communicates with suction chamber 23 via the orifice in port member 46, chamber 47 above such port member and communicating passages 48, 49 in the valve body 40 and head 36 respectively. Ball 44 is biased downwardly by a compression spring 58 which bears downwardly against a vertically slidable solenoid armature 50 carrying a stem member 51 which projects downwardly through the port in ring 46, the stem being substantially smaller in cross section than the port in the ring so that it does not prevent fluid conductive communication through the port.

The energization of the solenoid winding 52 is effected via conductors 54 under the control of any desired remote sensing means such as a thermostat located in a served zone. It will be noted that passage 55 which leads downwardly from the valve chamber 43 and communicates via connecting passage 56 with the discharge chamber 21 is always under discharge pressure, which tends to lift the valve ball and seat it against ring 46 whenever the compressor is running. Spring 49 plus the force of gravity is sufficient to hold the valve closed against discharge pressure when the solenoid is deenergized. When the solenoid is energized pin 51 is moved upwardly to free the ball which is then lifted by discharge pressure as indicated, closing off the suction side of the valve chamber. Discharge pressure then enters the cylinder 39 via passages 56, 55

chamber 43 passages 42, 41, forcing the valve 35 closed against its biasing spring 37. When the solenoid is deenergized, spring 49 forces the valve ball against the lower seat 45 reestablishing communication between suction chamber 23 and cylinder 39 via valve chamber 43. The suction pressure is insufficient to overcome the biasing spring 37 and valve 35 accordingly rises reestablishing communication between inlet port 26 and inlet passage 18 so that cylinder 15 again becomes operative.

With an arrangement as shown the unloading valve 35 is operative to selectively disable one-third of the compressor. By changing the number of unloading valves in proportion to the number of cylinders, however, and by selective operation of a plurality of such unloading valves, the proportionate variation of capacity and driving load can be changed within wide limits. The discharge pressure is always sufficient to fully close the valve or valves 35, so long as one or more cylinders are operating while, when. the solenoid is energized, the discharge pressure is immediately effective to force the ball 44 tightly against the upper seat 46 so that valve 35 opens quickly and fully and no throttling occurs in either direction.

This Detailed Description of Preferred Form of the Invention, and the accompanying drawings, have been furnished in compliance with the statutory requirement to set forth the .best mode contemplated by the inventor of carrying out the ministrative requirements of the PatentOfiice.

lclaim:

- 1. In a multicylinder refrigeration compressor having a com mon inlet for all cylinders, a discharge chamber in pressure conductive communication with all of the cylinders, an inlet chamber in the line of flow between less than all of the cylinders and said inlet, and an unloader valve movable to open and close communication between said inlet and said inlet chamber, the novelty which comprises in combination, actuating means for said unloader valve consisting of fluid motor means, and a servo valve movable to open and close communication between said fluid motor means and said discharge chamber, said servo valve comprising a shuttle valve for alternatively connecting the fluid motor means either to the discharge chamber or to said inlet chamber.

2. In a multicylinder refrigeration compressor having a common inlet for all cylinders, a discharge chamber in pressure conductive communication with all of the cylinders, an inlet chamber in the line of flow between less than all of the cylinders and said inlet, and an unloader valve movable to open and close communication between said inlet and said inlet chamber, the novelty which comprises in combination, actuating means for said unloader valve consisting of fluid motor means, and a servo valve movable to open and close communication between said fluid motor means and said discharge chamber, said servo valve comprising a shuttle valve for alternatively 1 connecting the fluid motor means either to the discharge chamber or to said inlet chamber, both the fluid motor and the servo valve being actuatable by fluid pressure derived from said discharge chamber, and electrically operable controlling means for the servo valve.

3. In a refrigeration compressor having a cylinder block defining a plurality of cylinders and having a head, a discharge chamber in the head in pressure conductive communication with all of the cylinders and a suction chamber in the head in pressure conductive communication with less than all of the cylinders, passage means for connecting the compressor inlet to said suction chamber, an unloading valve in the head movable to close and open the connection between said inlet and suction chamber, a fluid servo cylinder in the head, a piston in said servo cylinder for actuating said unloading valve, and a servo shuttle valve mounted externally on the head for connecting said servo cylinder either to the discharge chamber or the suction chamber.

1 ORM POJOSO {10-69 3, 578, 883 May 18, 1971 Patent No. Dated Inventor(s) Lawrence W. Cheney it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Cm. 2, line 27 and 37, "49" should be 58-. C01: 2, line 35, after "43" insert and.

Signed and sealed this 15th day of February 1972.

ttes't:

ROBERT GOTTSCHALK Commissioner of Patents EDWARD M.FLETCHER, JR. Attestinrg Officer Lemmmm

Claims (3)

1. In a multicylinder refrigeration compressor having a common inlet for all cylinders, a discharge chamber in pressure conductive communication with all of the cylinders, an inlet chamber in the line of flow between less than all of the cylinders and said inlet, and an unloader valve movable to open and close communication between said inlet and said inlet chamber, the novelty which comprises in combination, actuating means for said unloader valve consisting of fluid motor means, and a servo valve movable to open and close communication between said fluid motor means and said discharge chamber, said servo valve comprising a shuttle valve for alternatively connecting the fluid motor means either to the discharge chamber or to said inlet chamber.

2. In a multicylinder refrigeration compressor having a common inlet for all cylinders, a discharge chamber in pressure conductive communication with all of the cylinders, an inlet chamber in the line of flow between less than all of the cylinders and said inlet, and an unloader valve movable to open and close communication between said inlet and said inlet chamber, the novelty which comprises in combination, actuating means for said unloader valve consisting of fluid motor means, and a servo valve movable to open and close communication between said fluid motor means and said discharge chamber, said servo valve comprising a shuttle valve for alternatively connecting the fluid motor means either to the discharge chamber or to said inlet chamber, both the fluid motor and the servo valve being actuatable by fluid pressure derived from said discharge chamber, and electrically operable controlling means for the servo valve.

3. In a refrigeration compressor having a cylinder block defining a plurality of cylinders and having a head, a discharge chamber in the head in pressure conductive communication with all of the cylinders and a suction chamber in the head in pressure conductive communication with less than all of the cylinders, passage means for connecting the compressor inlet to said suction chamber, an unloading valve in the head movable to close and open the connection between said inlet and suction chamber, a fluid servo cylinder in the head, a piston in said servo cylinder for actuating said unloading valve, and a servo shuttle valve mounted externally on the head for connecting said servo cylinder either to the discharge chamber or the suction chamber.

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