WO2002023045A1

WO2002023045A1 - Rotary compressor with supercharge port

Info

Publication number: WO2002023045A1
Application number: PCT/US2001/024636
Authority: WO
Inventors: David H. Walker; Daniel Fischbach; Andrew C. Harvey; William D. Leary, Jr.
Original assignee: Foster-Miller, Inc.
Priority date: 2000-09-13
Filing date: 2001-08-06
Publication date: 2002-03-21
Also published as: AU2001279206A1

Abstract

A rotary compressor (10) with a supercharge port including a compressor cylinder (12); a housing (14, 16) for forming a compression chamber (18) with said compressor cylinder; an eccentric rotarymember (20) in the chamber for defining a compression volume and for drawing in to the volume through a suction port (30) a fluid to be compressed and discharging from the volume through a discharge port (32) the compressed fluid; an oscillating vane (34) extending into the chamber and bearing on the rotary member between the suction and discharge ports for separating the volume into intake (38) and compression (40) zones; and a supercharge port (50) in the compression zone for injecting at an intermediate pressure between that of the fluid at the suction port and the fluid at the discharge port a second charge of fluid to be compressed together with the fluid received from the suction port.

Description

ROTARY COMPRESSOR WITH SUPERCHARGE PORT

FIELD OF THE INVENTION This invention relates to a rotary compressor with a supercharge port.

GOVERNMENT RIGHTS This invention was made with U.S. Government support under Contract No. NAS 5-32761 awarded as an SBIR grant by NASA. The Government may have certain rights in the subject invention.

BACKGROUND OF THE INVENTION In conventional refrigeration systems involving evaporation, compression and condensation it is often desirable to improve the cooling ability by subcooling the refrigerant after condensation in order to promote a greater range of cooling during evaporation. There is shown in Fig. 1 the components of a conventional refrigeration system 100 that has been equipped with refrigerant subcooling. The subcooling is done by using a portion of the condensed refrigerant to subcool the remainder of the fluid before it undergoes evaporation. The refrigerant leaving the condenser 102 at 104 is split into two flows at 106. Most of the liquid is passed through the subcooler heat exchanger 108 where it is subcooled. The smaller portion of refrigerant flows through an expansion valve 110 that drops the pressure of the liquid and causes the liquid to flash. Any remaining liquid is evaporated as it passes through the subcooler heat exchanger. This evaporation removes heat from the refrigerant liquid, subcooling the liquid. Expansion of the small portion of refrigerant flow in the subcooler heat exchanger must be maintained at an intermediate pressure (between the condenser and evaporator pressures) by providing an intermediate pressure supercharge port 112 at the compressor; expansion valve 114, evaporator 116 and compressor 118 operate in a conventional manner. Supercharging has been demonstrated in certain types of compressors such as scroll or piston. Rotary compressors having an eccentric rotary member, such as rolling piston compressors lend themselves well to small and efficient applications but do not have supercharge ports.

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide an improved rotary compressor with a supercharge port.

It is a further object of this invention to provide an improved rotary compressor which uses a rolling piston.

It is a further object of this invention to provide an improved rotary compressor which provides greater cooling ability and efficiency.

It is a further object of this invention to provide an improved rotary compressor which is simple, more compact and efficient.

The invention results from the realization that a truly simple and effective supercharged rotary compressor can be achieved by employing a supercharge port in the housing of the compressor which is opened and closed by the movement of the rotary member, such as a rolling piston, to provide an input for fluid at pressures intermediate those at the suction and discharge ports for providing subcooling in a refrigeration system.

This invention features a rotary compressor with a supercharge port including a compressor cylinder and a housing for forming a compression chamber with the compressor cylinder. There is an eccentric rotary member in the chamber for defining a compression volume and for drawing into the volume through a suction port a fluid to be compressed and discharging from the volume through a discharge port the compressed fluid. An oscillating vane extends into the chamber and bears on the rotary member between the suction and discharge ports for separating the volume into intake and compression zones. A supercharge port in the compression zone injects at an intermediate pressure between that of the fluid at the suction port and the fluid at the discharge port a second charge of fluid to be compressed together with the fluid received from the suction port.

In a preferred embodiment the housing may include a front wall and a back wall for forming the chamber. The supercharge port may be in one of the walls. The supercharge port may be opened and closed by the rotary member. The supercharge port may be crescent shaped. The rotary member may be a rolling piston. The supercharge port may be opened by the rotary member as it closes the suction port.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

Fig. 1 is a schematic diagram of a conventional refrigeration system with refrigerant subcooling;

Fig 2 is a front elevational schematic diagram with portions removed of a rotary compressor with a supercharged port according to this invention embodied in a rolling piston compressor;

Fig. 3 is a more simplified schematic diagram showing the operation of the rotary compressor of Fig. 2 according to this invention; and

Fig. 4 is a more detailed side elevational sectional schematic diagram of the compressor of Fig. 2 according to this invention combined with a drive motor.

PREFERRED EMBODIMENT There is shown in Fig. 2 a rotary compressor 10 in the form of a rolling piston compressor which includes a compressor cylinder 12 sandwiched between a compressor backplate 14 and front plate 16, not shown in Fig. 2 but visible in Fig. 4. Compressor cylinder 12 sandwiched between the plates 14 and 16 defines a chamber 18 in which rolling piston 20 is driven eccentrically on bearing 22 mounted on eccentric shaft 24 driven by motor 26, not visible in Fig. 2 but shown in Fig. 4. The working volume or compression volume 28 is formed between the walls of chamber 18 and rolling piston 20. Fluid, such as refrigerant vapor is drawn in through suction port 30 and after compression pressurized refrigerant is discharged through discharge port 32. An oscillating vane 34 biased by axial wire spring 36 moves up and down in cavity 37 to maintain sealing engagement with rolling piston 20 and separates suction port 30 and discharge port 32 into two zones, an intake zone 38 and a discharge zone 40. There is a supercharge port 50, Fig. 3, in one of the walls or plates 14 and 16, not visible in Fig. 2 but shown clearly in Fig. 3. As rolling piston 20 moves eccentrically inside of chamber 18, it first draws in refrigerant through suction port 30, then compresses it as it rotates in the direction of arrow 52 and expels the compressed pressurized fluid at discharge port 32. During this action the piston also simultaneously covers, then uncovers, and once again covers discharge port 50. For example, in the first position piston 20-1 covers supercharge port 50. At this point suction port 30 is also closed by piston 20 in the 20-1 position. As piston 20 moves further to the position shown at 20-2, it begins to uncover suction port 30 for the next intake cycle while it now fully uncovers or opens supercharge port 50 for the introduction of the subcooling refrigerant at an intermediate pressure. Finally, in the third position 20-3, rolling piston 20 has once again covered supercharge port 50 and now the supercharged fluid is combined and compressed with the fluid originally introduced through suction port 30 in the last cycle and the combined pressurized fluid is discharged through discharge port 32.

In Fig. 3, using a refrigerant such as R-134a, a chamber of 1.22 in. diameter and a piston of 1.0 in diameter with a working volume of 0.061 in³ in a chamber and a desired intermediate pressure of 53.9 psia, the supercharge port with an area of 0.0019 in² has a dwell or opening period of 80° from the time it starts to open at 60 through the time when it is fully open 62, until it is closed 64. In these circumstances supercharge port 50 is set diametrically along the diameter 62 representing the fully opened position. The supercharge port is located at the position in the stroke of the rolling piston such that the port is opened when the suction intake port is closed and gas flow from the evaporator has ceased. The supercharge port is sized to remain open long enough to pass the amount of supercharge gas into the compressor needed to raise the pressure of the chamber from the evaporator pressure to the supercharge pressure. The value of the supercharge pressure is found by taking mass and energy balances at the subcooler heat exchanger and the compressor at the design evaporator and condenser pressures. One unique value of supercharge pressure will be found at these conditions that will satisfy the mass and energy balances. At this particular value of the supercharge pressure, maximum increase in cooling capacity will be obtained through refrigerant subcooling.

Rotary compressor 10 may be combined with drive motor 26, Fig. 4, whose housing 70 is fastened by means of bolts 72 to suction buffer manifold 74 which secures compressor 10 in place against motor 26. Rotor 26 includes a motor rotor/stator set 76 and shaft 78 which carries eccentric portion 24 that engages bearings 22 to drive rolling piston 20. Balance weights 80 are provided for shaft 78 along with suitable bearings 82, 84, and electrical connections 86. hi operation, refrigerant is drawn in through suction buffer plenum 74 and then through suction port 30 into chamber 18. It is discharged after compression through discharge port 14 into discharge pressure space 92 within motor housing 26; here it crosses through into discharge pipe 94.

Supercharge port 50, Fig. 3, is positioned so that when rolling piston 20 is in the position 20-1 where it is closing suction port 30, it is also closing supercharge port 50, but just barely. As soon as rolling piston 20 begins to rotate in the direction of arrow 52, rolling piston 20 begins moving toward position 20-2 which uncovers suction port 30 to begin the next cycle of intake as vane 34 descends to engage and seal rolling piston 20 in the position 20-1. As the piston moves to this position it also uncovers supercharge port 50 so that when it fully reaches the position of 20-2 supercharge port 50 is fully open at the center of its 80° period. Then as piston 20 continues to move, enlarging the intake zone 38 and decreasing the compression zone 40, rolling piston 20 begins to cover or close supercharge port 50 and by the time it fully reaches position 20-3 rolling piston has completely covered or closed supercharge port 50. The particular open area of the supercharge port 50 is determined by the mass flow rate of supercharge gas that must flow into the compressor chamber and the average pressure difference between the subcooler heat exchanger and the compressor chamber. The value of this pressure difference is largest at the opening of the supercharge port. The value of the pressure difference decreases as the pressure in the compressor chamber increases; the difference is zero when the supercharge port is closed.

Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words "including", "comprising", "having", and "with" as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.

Other embodiments will occur to those skilled in the art and are within the following claims:

What is claimed is:

Claims

CLAIMS A rotary compressor with a supercharge port comprising: a compressor cylinder a housing for forming a compression chamber with said compressor cylinder; an eccentric rotary member in said chamber for defining a compression volume and for drawing into said volume through a suction port a fluid to be compressed and discharging from said volume through a discharge port the compressed fluid; an oscillating vane extending into said chamber and bearing on said rotary member between said suction and discharge ports for separating said volume into intake and compression zones; and a supercharge port in said compression zone for injecting at an intermediate pressure between that of the fluid at the suction port and the fluid at the discharge port a second charge of fluid to be compressed together with the fluid received from said suction port.

2. The rotary compressor of claim 1 in which said housing includes a front wall and a back wall forming said chamber.

3. The rotary compressor of claim 2 in which said supercharge port is in one of said walls.

4. The rotary compressor of claim 3 in which said supercharge port is opened and closed by said rotary member.

5. The rotary compressor of claim 1 in which said supercharge port is crescent shaped.

6. The rotary compressor of claim 1 in which said rotary member is a rolling piston.

7. The rotary compressor of claim 1 in which said supercharge port is opened by said rotary member as it closes said suction port.