GB2099081A

GB2099081A - Sliding-vane rotary compressor

Info

Publication number: GB2099081A
Application number: GB8113680A
Authority: GB
Original assignee: DENCO AGR Ltd
Current assignee: DENCO AGR Ltd
Priority date: 1981-05-05
Filing date: 1981-05-05
Publication date: 1982-12-01

Abstract

In a compressor for e.g. a refrigerant, an end plate (5) of a stator cavity accommodating the rotor (1) is deflectable away from the rotor to allow any liquid, such as lubricating oil, trapped on the high-pressure side of the rotor to escape and thereby obviate damage to the rotor vanes (3). The end plate is biassed towards the rotor by e.g. springs (6) and the pressure of fluid which escapes from the high pressure side of the rotor and collects under a cover (7) fixed to the stator (2). <IMAGE>

Description

SPECIFICATION Rotary vane compressor This invention relates to rotary vane compressors.

The invention provides a rotary vane compressor comprising a rotor rotatable in a cavity, an end of which perpendicular to the axis of the rotor is defined by a member biassed towards the rotor but deflectable away from the rotor to allow any liquid trapped on the high pressure side of the compressor to escape.

The liquid may escape from the cavity or may escape to the low pressure side of the compressor.

The fact that the end of the cavity is formed by a deflectable member tends to prevent breakage of the vanes and/or of the discharge valve which was hitherto prone to occur. Such liquid could form in the spaces between the vanes by migrating from an evaporator downstream of the compressor and going into solution with oil lubricating the compressor. Alternatively, such liquid could simply be lubricating oil.

There may be provided resilient means for biassing the deflectable member towards the rotor, to maintain the cavity closed. Alternatively, or in addition, the arrangement may be such that leakage pressure from the high pressure side of the compressor is used to bias the deflectable member towards the rotor. Thus, the deflectable member may have an aperture through which a shaft of the rotor passes and through which the gas to be compressed can flow. A high pressure zone may thus be maintained on the side of the deflectable member remote from the rotor. A cover may be provided on the side of the deflectable member remote from the rotor, which cover forms a seal with the member that defines the rotor cavity. if resilient means are provided, they may be located between the deflectable member and the cover.

A rotary vane compressor constructed in accordance with the invention will now be described, by way of example, with refere ,e to the accompanying drawing, which is an axial sectional view of the compressor.

Referring to the drawing, the compressor comprises a rotor 1, a stator 2 and vanes 3. The rotor is cylindrical and is mounted off-centre in the stator. As the rotor rotates about its shaft 4, (rotatable in roller bearings 4a and 4b) the compartments defined between adjacent vanes become progressively smaller and larger to give smooth compression and expansion during one revolution. An inlet 2a and an outlet 2b are provided at appropriate positions.

The compressor is driven by a motor (not shown) which may be of the form shown in US Patent No. 4 049 410.

The top end of the rotor cavity is defined by a deflectable plate 5 which is urged against the stator 2 to close the cavity by means of springs 6 (at least three such springs are provided) which bear against a cover 7 which is spaced from the plate 5 and which is secured to the stator 2. There is a slight clearance between the shaft 4 and an aperture 8 in the plate 5 so that the gas being compressed can pass through the aperture. There is also a slight clearance between the rotor 1 and the plate 5 (the stator 2 against which the plate 5 seats being marginally thicker than the rotor). The cover 7 is secured to the stator 2 in a gas-tight fashion.

In operation, when the compressor starts up, the springs 6 maintain the rotor cavity closed so that the gas is compressed in the compressor compartments in the usual way. When the compressor is working, the high pressure generated on one side of the compressor leaks via the aperture 8 to the space between the plate 5 and the cover 7. Since the pressure above the plate 5 is now high, but that below is not, since the high pressure is exhausted directly to the low pressure side, the plate 5 is now urged towards the rotor by the leakage pressure from the high pressure side as well as by means of the springs 6.

If any liquid becomes trapped between the vanes, instead of the vanes or the discharge valve being broken (as hitherto sometimes happened), the plate 5 simply lifts and the liquid vents to the other side of the plate 5, or to the low pressure side of the compressor.

If desired, a similar pressure relief mechanism may be employed at the bottom end of the rotor cavity as well as at the top.

If desired, the cover 7 may be provided with an outlet to vent any liquid escaping to the upper side of the plate 5. In this case, high pressure must be maintained above the cover 7.

The compressor may be a refrigeration compressor.

1. A rotary vane compressor comprising a rotor rotatable in a cavity, an end of which perpendicular to the axis of the rotor is defined by a member biassed towards the rotor but deflectable away from the rotor to allow any liquid trapped on the high pressure side of the compressor to escape.

2. A rotary vane compressor as claimed in Claim 1, wherein resilient means is provided for biassing the deflectable member towards the rotor.

3. A rotary vane compressor as claimed in Claim 1 or 2, wherein the arrangement is such that leakage pressure from the high pressure side of the compressor is used to bias the deflectable member towards the rotor.

4. A rotary vane compressor as claimed in Claim 3, wherein the deflectable member has an aperture through which the shaft of the rotor passes and through which the gas to be compressed can flow.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rotary vane compressor This invention relates to rotary vane compressors. The invention provides a rotary vane compressor comprising a rotor rotatable in a cavity, an end of which perpendicular to the axis of the rotor is defined by a member biassed towards the rotor but deflectable away from the rotor to allow any liquid trapped on the high pressure side of the compressor to escape. The liquid may escape from the cavity or may escape to the low pressure side of the compressor. The fact that the end of the cavity is formed by a deflectable member tends to prevent breakage of the vanes and/or of the discharge valve which was hitherto prone to occur. Such liquid could form in the spaces between the vanes by migrating from an evaporator downstream of the compressor and going into solution with oil lubricating the compressor. Alternatively, such liquid could simply be lubricating oil. There may be provided resilient means for biassing the deflectable member towards the rotor, to maintain the cavity closed. Alternatively, or in addition, the arrangement may be such that leakage pressure from the high pressure side of the compressor is used to bias the deflectable member towards the rotor. Thus, the deflectable member may have an aperture through which a shaft of the rotor passes and through which the gas to be compressed can flow. A high pressure zone may thus be maintained on the side of the deflectable member remote from the rotor. A cover may be provided on the side of the deflectable member remote from the rotor, which cover forms a seal with the member that defines the rotor cavity. if resilient means are provided, they may be located between the deflectable member and the cover. A rotary vane compressor constructed in accordance with the invention will now be described, by way of example, with refere ,e to the accompanying drawing, which is an axial sectional view of the compressor. Referring to the drawing, the compressor comprises a rotor 1, a stator 2 and vanes 3. The rotor is cylindrical and is mounted off-centre in the stator. As the rotor rotates about its shaft 4, (rotatable in roller bearings 4a and 4b) the compartments defined between adjacent vanes become progressively smaller and larger to give smooth compression and expansion during one revolution. An inlet 2a and an outlet 2b are provided at appropriate positions. The compressor is driven by a motor (not shown) which may be of the form shown in US Patent No. 4 049 410. The top end of the rotor cavity is defined by a deflectable plate 5 which is urged against the stator 2 to close the cavity by means of springs 6 (at least three such springs are provided) which bear against a cover 7 which is spaced from the plate 5 and which is secured to the stator 2. There is a slight clearance between the shaft 4 and an aperture 8 in the plate 5 so that the gas being compressed can pass through the aperture. There is also a slight clearance between the rotor 1 and the plate 5 (the stator 2 against which the plate 5 seats being marginally thicker than the rotor). The cover 7 is secured to the stator 2 in a gas-tight fashion. In operation, when the compressor starts up, the springs 6 maintain the rotor cavity closed so that the gas is compressed in the compressor compartments in the usual way. When the compressor is working, the high pressure generated on one side of the compressor leaks via the aperture 8 to the space between the plate 5 and the cover 7. Since the pressure above the plate 5 is now high, but that below is not, since the high pressure is exhausted directly to the low pressure side, the plate 5 is now urged towards the rotor by the leakage pressure from the high pressure side as well as by means of the springs 6. If any liquid becomes trapped between the vanes, instead of the vanes or the discharge valve being broken (as hitherto sometimes happened), the plate 5 simply lifts and the liquid vents to the other side of the plate 5, or to the low pressure side of the compressor. If desired, a similar pressure relief mechanism may be employed at the bottom end of the rotor cavity as well as at the top. If desired, the cover 7 may be provided with an outlet to vent any liquid escaping to the upper side of the plate 5. In this case, high pressure must be maintained above the cover 7. The compressor may be a refrigeration compressor. CLAIMS

5. A rotary vane compressor as claimed in Claim 3 or 4, wherein a cover is provided on the side of the deflectable member remote from the rotor, which cover forms a seal with the member that defines the rotor cavity.

6. A rotary vane compressor according to Claim 1, substantially as herein described with reference to, and as shown in, the accompanying drawing.