US3791776A

US3791776A - Reciprocating cylinder type compressor having unloading means

Info

Publication number: US3791776A
Application number: US00240590A
Authority: US
Inventors: W Grant
Original assignee: Vilter Manufacturing LLC
Current assignee: Copeland Industrial LP
Priority date: 1972-04-03
Filing date: 1972-04-03
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

Unloading means for a reciprocating type compressor, for refrigeration equipment or the like, said means placing the discharge chamber in communication with the suction side of the compressor and including a one-way valve and means for actuating the valve at the proper time. The arrangement is such that the individual cylinders of a multi-cylinder compressor can be independently unloaded as desired.

Description

United States Patent Grant l l Feb. 12, 1974 [54] RECIPROCATING CYLINDER TYPE 1.307.061 6/l9l9 ()lscn 417/440 x COMPRESSOR HAVING UNLOADNG 2,036,846 4/1936 Aldingcr 4|7/307 X MEANS FOREIGN PATENTS ()R APPLICATIONS [75] Inventor: Whitney 1. Grant, Muskego, Wis. 260,150 8/1926 lluly 4l7/307 505,027 l2/l954 lt'l 4l7 307 [73] Assignee: Vilter Manufacturing Corporation, d y

M'lwaukee Primary Examiner-Carlton R. Croyle [22] Filed: Apr. 3, I972 Assistant Examiner-Richard Sher [21 1 pp No 240 590 Attorney, Agent, or Firm-James E. Nilles 57 ABSTRACT [52] U.S. Cl. 417/440, 4l7/307 l 1 [51 Int. Cl. F04b 49/02 Unloadmg means for a reclprocatmg type compressor of Search. for refrigeration equipment or the like, said means 417/275 31 placing the discharge chamber in communication with the suction side of the compressor and including a [56] References Cited one-way valve and means for actuating the valve at the proper time. The arrangement is such that the in- UNITED STATES PATENTS dividual cylinders of a multi-cylinder compressor can :almen, be independently unloaded as desired. oung 2,715,992 8/1955 Wilson 417/309 2 Claims, 2 Drawing Figures PAIENIED FEB sum 1 OF 2 RECIPROCATING CYLINDER TYPE COMPRESSOR HAVING UNLOADING MEANS BACKGROUND OF THE INVENTION The general organization of the compressor C and its This invention pertains generally to refrigeration operation are as follows. The compressor includes a equipment and more particularly to reciprocating type compressors having a piston that reciprocates in a cylinder to form an expansible compression chamber, and the compressor also having a suction side for the gas, and a high pressure, discharge side. More specifically, the invention pertains to unloading means for the individual compression chambers of such a compressor.

This invention is an improvement over the devices as shown in the following United States patents, all of which have been assigned to an assignee common with the present invention; U.S. Pat. No. 3,540,470 issued Nov. 17, 1970 to Schmid and Grant and entitled Diaphragm Valve for Compressors; U.S. Pat. No. 3,131,856 issued Mar. 5, 1964 to Michener entitled Reciprocating Piston 'Type Gas Compressor"; U.S. Pat. No. 3,490,683, issued Jan. 20, 1970 to Kocher and entitled Gas Compressor; and U.S. Pat. No. 3,261,541 to Kocher issued July 19, 1966 and entitled Compressor Unloading Means.

SUMMARY OF THE INVENTION The present invention provides a reciprocating type refrigerant compressor, which compressor is of the type which includes a suction chamber, a cylinder and reciprocating piston therein which form a compression chamber. Gas from said suction chamber enters the compression chamber, is compressed and then is discharged to a discharge outlet. The compressor of the present invention has cylinder unloading means which comprises conduit means that place the compression chamber in fluid communication with the suction chamber, and this conduit means has a one-way check valve located closely adjacent the compression chamber for permitting gas only to leave the compression chamber, and the conduit means also has an actuatable 1 valve whereby when the actuatable valve is open, gas

from said compression chamber can pass through said one-way check valve into said suction chamber, thereby unloading said compression chamber.

The unloading means mentioned above is located closely adjacent the compression chamber whereby the volume of gas between the chamber and the valve is very small, contributing to high efficiency of the compressor. The arrangement is such that the volume of gas between the check valve and the actuatable valve is of no consequence since this gas will be at discharge pressure because when the actuatable valve is closed it cannot flow back into the cylinder.

These and other objects and advantages of the present invention will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings.

' BRIEF DESCRIPTION OF THE DRAWINGS main housing 1 having a suction conduit 2 which communicates with a suction chamber 3 at the low pressure side of the compressor. Gas to be compressed is drawn into the suction chamber, compressed, and then the high pressure refrigerant gas is charged through the conduit 4 for discharge to a condenser (not shown) or the like of a refrigerant system. The compressor includes any number of cylinders 6 in which their respective pistons 7 are reciprocated in suction and compression strokes by the cranks 8 which are connected to the throws of a crankshaft 9. The crankshaft 9 is journalled in suitable anti-friction bearings 10 and is driven by a power source (not shown). An oil pump 12 is located at and driven by the end of the crankshaft and acts to supply lubricating fluid such as oil through various passages (not shown) and to the various parts of the compressor in the known manner.

Mounted on the upper end of each of the cylinders is a flat enclosure plate 20 which is urged into sealing relationship with the upper, open end of the cylinder by a relatively strong helical spring 22 acting through an annular spring guide 25.

The plates 20 have a series of circumferentially spaced discharge ports 23, a plurality of conventional plate diaphragms 24 extend across the ports 23 to seal them, so the diaphragm plates can raise within guide 25 and thereby permit gas to pass through ports 23 in the conventional manner.

Cylinder unloading means are provided for each of the cylinders so that each can be separately unloaded if desired, as follows. A conduit 30 is in fluid communication with the compression chamber 31 of the cylin' ders and extends through the enclosure plate 20. A one-way check valve, such as the check valve 36 is located in the conduit 30 and closely adjacent the closure plate 20. The conduit 30 is in communication with another conduit 31a that leads to the suction chamber 3.

A solenoid operated valve 38 is located in conduit 30 and may be energized, that is opened, by an automatic means (not shown). A small connecting passage 40 is located centrally through the threaded chamber 41 which extends through plate 20 and is held captive therein by nuts 42. A coupling 43 is threaded on member 41 and contains passage 44 and a valve seat 45 for ball 36.

The passage 40 thus connects the interior of the compression chamber 31 with the valve 36 and this passage 40 is sized so that the pressure in the cylinder never reaches a level high enough to open the discharge valve 36, which is held closed by the same gas pressure as that which exists in the discharge chamber.

The valve 36 is located closely adjacent the chamber 31 and its position is such that flow of gas can only be from the cylinder to the solenoid valve, and without any retum flow to the chamber 31, and this is important to high compressor efficiencies when the compressor is loaded. With the check valve 36 so located, the volume of gas between the top of the cylinder and the check valve is a very minimum and approximates the volume in the connecting passage 40. This volume is considered as a part of the clearance volume; the

smaller the total clearance volume in the compressor, the higher the efficiency.

The volume of gas in the line 30 between the check valve 36 and the solenoid valve 38 is of no great concern since this gas will be at discharge pressure when the solenoid valve 38 is closed, and cannot flow back into the cylinder and expand during the suction stroke due to the check valve 36.

In the arrangement shown, the conduit 30 is shown connected to the top of the cylinder, but other locatfons and dispositions of the unloading conduit are of course possible. Because the check valve 36 is located at the discharge valve assembly in plate 20 and closely adjacent the chamber 31, solenoid valve 38 can be located in any of a variety of locations in conduit 30, the check valve acting to prevent re-expansion back into the cylinder of the gas that is trapped beyond the check valve.

When it is desired to unload the cylinder chamber 31,

the valve 38 is opened and the upward movement of taking place and no gas entering the discharge chamber a during unloading, thereby the capacity compression is reduced and power is also reduced in approximately direct proportion to the reduction in capacity.

It will also be noted that a similar unloading conduit a extends from the other cylinder shown and has a similar solenoid operated valve 38a and also communicates with the suction chamber 3. Valves 38 and 38a may be operated independently to unload the cylinders selectively as desired.

The present unloading arrangement is simple with a minimum number of required parts. Complicated internal unloading mechanism, as for example shown in the prior art patent devices previously referred to, have been eliminated. As a result, wear and replacement of parts and service are reduced to a minimum.

I claim:

1. A reciprocating type, refrigerant compressor of the type having a suction chamber, a cylinder and reciprocating piston which form a compression chamber for receiving low pressure gas from said suction chamber, and a discharge outlet which receives compressed gas from said compression chamber, and cylinder unloading means for said compressor comprising conduit means between said compression chamber and said suction chamber, said conduit means having a one-way check valve affording substantially unrestrained gas flow from said compression chamber into a closely adjacent end portion of said conduit means and preventing return flow of gas from said conduit means into said compression chamber; and an actuatable valve downstream from said check valve whereby when said actuatable valve is open, gas from said compression chamber can pass through said one-way check valve into said suction chamber, thereby unloading said compression chamber, said compressor including a closure plate mounted across the compression chamber, and a threadable member extending through said closure plate and having a central passage therein in communication with said compression chamber, and wherein said one-way check valve includes a coupling fixed to said threadable member and having a valve seat formed therein and a shiftable ball in said coupling and abuttable on said seat.

2. A reciprocating type, refrigerant compressor of the type having a suction chamber, a cylinder and reciprocating piston which form a compression chamber for receiving low pressure gas from said suction chamber, a closure plate mounted across the compression chamber, resilient means for resiliently biasing said closure plate on said cylinder, said plate having discharge valve means, and a discharge outlet which receives compressed gas from said compression chamber, conduit means extending between said compression chamber and said suction chamber, said conduit means including a threadable member extending through said closure plate and having a central passage therein, a one-way check valve affording substantially unrestrained gas flow from aportion of said threadable member closely adjacent to said closure plate and preventing return flow of gas from said conduit means into said compression chamber; said check valve including a coupling fixed to said threadable member and having a valve seat formed therein and a shiftable ball in said coupling and abuttable on said seat, and said conduit means also having a solenoid operated valve downstream from said check valve whereby when said solenoid operated valve is open, gas from said compression chamber can pass through said one-way check valve into said suction chamber, thereby unloading said compression chamber.

Claims

2. A reciprocating type, refrigerant compressor of the type having a suction chamber, a cylinder and reciprocating piston which form a compression chamber for receiving low pressure gas from said suction chamber, a closure plate mounted across the compression chamber, resilient means for resiliently biasing said closure plate on said cylinder, said plate having discharge valve means, and a discharge outlet which receives compressed gas from said compression chamber, conduit means extending between said compression chamber and said suction chamber, said conduit means including a threadable member extending through said closure plate and having a central passage therein, a one-way check valve affording substantially unrestrained gas flow from a portion of said threadable member closely adjacent to said closure plate and preventing return flow of gas from said conduit means into said compression chamber; said check valve including a coupling fixed to said threadablE member and having a valve seat formed therein and a shiftable ball in said coupling and abuttable on said seat, and said conduit means also having a solenoid operated valve downstream from said check valve whereby when said solenoid operated valve is open, gas from said compression chamber can pass through said one-way check valve into said suction chamber, thereby unloading said compression chamber.