EP0436331A1

EP0436331A1 - Dual flow single cell rotary compressor

Info

Publication number: EP0436331A1
Application number: EP90313625A
Authority: EP
Inventors: James Day, (Nmn)
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1990-01-02
Filing date: 1990-12-14
Publication date: 1991-07-10
Also published as: CA2030063A1

Abstract

A rotary compressor having a frame defining a cylindrical aperture (11) and a vane slot (13) extending radially outwardly from the cylindrical aperture is provided. The frame also defines a first inlet port (43) extending radially outwardly from said cylindrical aperture through the frame on one side of the vane slot. A second inlet (53) extends radially outwardly from the cylindrical aperture through the frame and is situated substantially diametrically opposite the vane slot. A first check valve (45-51) is situated in the first inlet port for permitting flow only radially inwardly. A vane (33) is slidably mounted in the vane slot. Two journal bearing plates (21 (not in Fig. 1) and 23) each defining a journal bearing extending axially therethrough, are situated on either side of the cylindrical aperture defining a cylindrical chamber. One journal bearing plate (21) further defines an outlet port (55) extending axially through it. The outlet port is situated on the other side of the vane from the first inlet port. A second check valve is situated in the outlet port for permitting flow only from the cylindrical chamber. A shaft (15) extends through the cylindrical chamber and is rotatably mounted in the journal bearings of the first and second journal bearing plates. The portion of the shaft situated in the cylindrical chamber has an eccentrically extending circular lobe (27). A rolling piston (31) surrounds the circular lobe and contacts a portion of the cylindrical chamber periphery and the two journal plates.

Description

This application is related to our co-filed European Application No. (RD-20032) having the same title.
The present invention relates to a two stage compressor and more specifically to a rotary compressor for pumping two separate refrigerant flows to a single higher pressure.
Some refrigerant cycles such as that disclosed in US Patent No. 4910972 entitled "Refrigerator Systems With Dual Evaporators for Household Refrigerators" require two separate compressors or a single two-stage compressor.
It is an object of the present invention to provide a rotary compressor capable of pumping two separate refrigerant flows at different pressures through a single cavity to a single higher pressure.
In one aspect of the present invention a rotary compressor having a frame defining a cylindrical aperture and a vane slot extending radially outwardly from the cylindrical aperture is provided. The frame also defines a first inlet port extending radially outwardly from said cylindrical aperture through the frame on one side of the vane slot. A second inlet valve extends radially outwardly from the cylindrical aperture through the frame and is situated substantially diametrically opposite the vane slot. A first check valve is situated in the first inlet port for permitting flow only radially inwardly. A vane is slidably mounted in the vane slot. Two journal bearing plates each defining a journal bearing extending axially therethrough, are situated on either side of the cylindrical aperture defining a cylindrical chamber. The second journal bearing plate further defines an outlet port extending axially through the journal plate. The outlet port is situated on the other side of the vane from the first inlet port. A second check valve is situated in the outlet port for permitting flow only from the cylindrical chamber. A shaft extends through the cylindrical chamber and is rotatably mounted in the journal bearings of the cover and journal bearing plates. The portion of the shaft situated in the cylindrical chamber has an eccentrically extending circular lobe. A piston surrounds the circular lobe and contacts a portion of the cylindrical chamber periphery and the two journal bearing plates.
The objectives and advantages of the invention can be more readily ascertained from the following description of a preferred embodiment when read in conjunction with the accompanying drawings in which:

Figure 1 is a partially cutaway view of a dual flow rotary compressor out of its hermetically sealed housing in accordance with the present invention;
Figure 2 is a section view taken along the lines II-II in Figure 1; and
Figures 3, 4 and 5 Schematically illustrate the operation of the rotary compressor showing the piston in three sequential positions.

Referring now to the drawing wherein like numerals indicate like elements throughout and particularly Figures 1 and 2 thereof, a dual flow single cell rotary compressor 5 is shown which is typically situated in a hermetically sealed housing (not shown). The rotary compressor has a frame 7 defining a cylindrical aperture 11 and a vane slot 13 extending radially outwardly from the cylindrical aperture. A hollow shaft 15 is situated concentrically in the cylindrical aperture. The shaft is rotatably supported by a journal bearing 17 located in a journal bearing plate 21 on one side and a journal bearing plate 23 having a journal bearing 25 on the other. The frame 7, the journal bearing plate 21 and the journal bearing plate 23 together define a cylindrical chamber. The portion of the shaft situated in the cylindrical chamber has an eccentrically Positioned circular lobe 27 extending therefrom. The circular lobe is surrounded by a close fitting annular member called a rolling piston 31. The rolling piston is in contact with the circular lobe and a portion of the cylindrical wall of the chamber. The piston is free to rotate about the circular lobe. A vane 33 is slidably mounted in the vane slot 13 in the frame biased towards the piston contacting the piston by a spring 35. An electric motor rotor 37 is mounted on the portion of the shaft extending through the journal bearing plate 21. The portion of the shaft extending through the journal bearing plate is closed off by a cap 41 which has a friction fit.
The cylindrical chamber is in flow communication with a first inlet port 43 extending radially outwardly from the cylindrical chamber through the frame 7 situated adjacent to one side of the vane 33. A quick acting check valve which permits gas flow into the chamber but not out is positioned in the port close to the chamber. In a preferred embodiment the check valve comprises a floating hinge check valve. A sleeve 45 is press fit in the first inlet port with a spring 47 having one end wider than the sleeve situated in the port. The spring extends through the sleeve toward the cylindrical chamber and secured to the center of a cover plate 51. The cover plate has a diameter larger than the sleeve but smaller than the port. The spring 47 biases the cover plate towards the polished end of the sleeve. The cover plate 51 is shown by dashed lines in the open position and indicated by reference numeral 51.
A second inlet port 52 extends radially inwardly diametrically across from the vane. Tube 53 is in flow communication with this port. A check valve is not needed in this port.
An outlet port 55 extends from a position near the cylindrical chamber on the opposite side of the vane 33 from the first inlet port axially through the journal bearing plate 21 through a check valve. A reed check valve 57 is shown in the Figures comprising a flexible piece of metal secured to the plate. A portion of the flexible piece 59 covers the outlet port permitting flow only from the cylindrical chamber. The exterior portion of the journal plate 21 is covered by a close fitting housing 61 which serves a muffler.
The vane 33 divides the volume surrounding the piston 31 into a high pressure and a low pressure region. The piston contacts the cylindrical chamber walls in a sweeping circular motion which moves in the same direction and at the same rate as the shaft 17 rotates. The operation of the compressor is shown in the sequence of schematic Figures 3, 4 and 5 showing different positions of the piston. The pressures used in describing the operation are those needed to operate the cycle described in US Patent 4910972, the disclosure in which is incorporated herein by reference. Other pressures of course could be supplied and achieved by the rotary compressor. In the Figures the shaft rotates in the clockwise direction as viewed.
Referring now to Figure 3, low pressure vapor (17 psi) is admitted through the first inlet port 43 when the piston 31 passes the inlet port and until the piston begins to uncover the second inlet port 52, filling the portion of the cylindrical chamber between the vane and the piston on the first inlet port side.
In Figure 4, the second inlet port 52 is uncovered by the piston 31 admitting the higher pressure gas (39 psi) The higher pressure gas fills the chamber mixing with the lower pressure gas closing the first inlet port check valve cover 51.
In Figure 5, the piston 31 has rotated almost 360° from the previous position in Figure 4 compressing the gas before it and out the outlet port at high pressure (150 psi).
The compression ratio is approximately 4:1 in this configuration. Changing the circumferential position of the second inlet port will change the compression ratio.
The shaft is driven by an electric motor the stator of which is not shown. The spring 35 holds the vane 33 against the piston 31 during initial operation. Once the cycle starts the high pressure gas is discharged into the hermetically sealed housing (not shown) surrounding the frame 7. The high pressure gas pushes the vane against the rolling piston. Tubes connected to the two inlet ports pass through the hermetically sealed housing the outlet tube is in flow communication with the housing.
The frame, cover plate and journal plate can be fabricated from cast iron. The piston and vane can be fabricated from steel.
The foregoing has described a rotary compressor capable of pumping two separate refrigerant flows at different pressures through a single cavity to a higher pressure.
While the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention.

Claims

A rotary compressor comprising: a frame defining a cylindrical aperture and a vane slot extending radially outwardly from said cylindrical aperture, said frame also defining a first inlet port extending radially outwardly from said cylindrical aperture through said frame on one side of said vane slot and a second inlet port extending radially outwardly from said cylindrical aperture through said frame, said second inlet port situated substantially diametrically opposite said vane slot;
a first check valve situated in said first inlet port for permitting flow only radially inwardly;
a vane slidably mounted in said vane slot;
a first journal bearing plate defining a journal bearing extending axially therethrough;
a second journal bearing plate defining a journal bearing extending axially therethrough, said first and second journal bearing plates situated on either side of said cylindrical aperture defining a cylindrical chamber, said second journal bearing plate further defining an outlet port extending axially through said second journal bearing plate, said outlet port situated on the other side of said vane from said first inlet port;
a second check valve situated in said outlet port for permitting flow only from said cylindrical chamber;
a shaft extending through said cylindrical chamber and rotatably mounted in the journal bearings of said first journal bearing plate and second journal bearing plate, the portion of said shaft situated in said cylindrical chamber having an eccentrically extending circular lobe; and
a piston comprising an annular ring surrounding said circular lobe and contacting a portion of said cylindrical chamber periphery and said first and second journal bearing plates.