GB2233713A

GB2233713A - Rotary compressor

Info

Publication number: GB2233713A
Application number: GB9012761A
Authority: GB
Inventors: Wah Kai Lam
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-06-08
Filing date: 1990-06-08
Publication date: 1991-01-16
Also published as: GB9012761D0

Abstract

A compressor in which one or more vanes sweep through an annular chamber circumferentially divided by an abutment. The vane(s) rotate about an axis coincident with the longitudinal axis of the annular chamber. The vane(s) rotate(s) either unidirectionally or in angular oscillations, in which case the abutment is either movable or fixed respectively. Flow of working fluid into and out of the compressor is controlled by one-way inlet and outlet valves. The outlet valve(s) may be combined with an adjustable pressure regulator (Figs. 4 to 6). The working fluid may be a compressible gas, eg. air, or an incompressible liquid, eg. oil or water. A rotary abutment compressor is described with reference to Figs. 1 to 3 and an oscillating vane compressor is described with reference to Figs. 7 to 13.

Description

ROTARY-VANE COMPRESSORS This invention relates to rotary-vane compressors for handling air, liquids, and gases other than air.

The art of rotary-vane compression or pumping is well documented. The engineering principle is well-established. However, most previously known rotary-vane air compressors have multiple sliding vanes mounted on an eccentric rotor. As the number of vanes increases, the contact surface area between vanes and the stator increases. Also, the choice of the number of vanes is strongly determined by the fluid to be pumped or compressed. Once fabricated, flexibility in handling different fluids is limited. Also, in conventional rotary-vane compressors, the reduction in volume between vanes is fixed and the air cannot be delivered at intermediate pressures.

It is a primary object of this invention to provide a new form of rotary-vane compressor for compressing air or another working fluid. Subsidiary objects of this invention are: (i) To reduce friction by use of one or two rotating vanes.

(ii) To reduce vibration by use of a centred compressor shaft.

(iii) To have the ability to handle different types of fluids in one single machine.

(iv) To have the ability to deliver air (or other fluids) at intermediate pressures.

According to the present invention there is provided a rotary-vane compressor for compressing a working fluid, said compressor comprising a stator having an annular chamber with a longitudinal axis, a vane means rotatably mounted for circumferential movement in said annular chamber about a rotation axis coincident with the longitudinal axis of said annular chamber, an abutment means circumferentially dividing said annular chamber, an inlet valve means for admitting working fluid to said annular chamber, an outlet valve means for discharging working fluid from said annular chamber, and vane drive means for rotatably driving said vane means in said annular chamber such that the vane means undergoes cyclic variation of its circumferential separation from the abutment means whereby working fluid is cyclically drawn through the inlet valve means into said annular chamber between the vane means and the abutment means, compressed, and discharged through the outlet valve means from said annular chamber.

Said abutment means may be either a fixed abutment means or a movable abutment means. In the case where said abutment means is a movable abutment means, the abutment means may be a rotary abutment rotatable about an axis parallel to and offset from the the rotation axis of the vane means, the rotary abutment being coupled to said vane drive means to be rotatably driven synchronously with the vane means, the rotary abutment having a peripheral abutment surface which is cylindrical between one or more peripheral cut-outs, the axial offset of the rotary abutment and its phase angle with respect to the vane means being such that in operation of the compressor, said peripheral abutment surface divides the annular chamber and said one or more peripheral cut-outs permit circumferential passage of the vane means during unidirectional rotation thereof.

In the alternative case where said abutment means is a fixed abutment means, said vane drive means is preferably such that the vane means is rotably driven in angular oscillations which are preferably substantially less than a complete revolution in magnitude.

The compressor may have a single movable abutment co-operating with a single radially projecting vane, the vane drive means causing unidirectional rotation of the vane in operation of the compressor.

Alternatively, the compressor may have a single fixed abutment co-operating with a diametrically opposed pair of radially mounted vanes, the vane drive means angularly oscillating the vanes through a rotational angle of less than half of a complete revolution in operation of the compressor, said vane drive means preferably comprising a crank drive mechanism having a driven crank arm rotationally secured to the vane means and linked by a pivotally coupled connecting rod to a unidirectionally rotatable drive crank arm, said driven crank arm having a radius more than twice as great as the radius of the drive crank arm.

Whether said abutment means is fixed or movable, at least the inner wall of the annular chamber is preferably formed by the cylindrical periphery of a rotatable hub on which the rotatable vane means is mounted.

Said inlet valve means and said outlet valve means preferably each comprise a spring-biassed poppet valve.

Alternatively, said inlet valve means and said outlet valve means may each comprise a respective cam-operated valve, the cam or cams which operate said valves being driven synchronously with the rotating vane means in operation of the compressor for operation of the respective valves at predetermined angular positions of the vane means.

Said working fluid may comprise a compressible gas such as air, or said working fluid may comprise an incompressible liquid such as oil or water.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings wherein Fig. 1 is an angled elevation from the front and to the left of a first embodiment of rotary-vane air compressor in accordance with the invention; Fig. 2 is a rear elevation of the compressor of Fig. 1; Fig. 3 is a vertical sectional elevation of the compressor of Fig. 1, taken in a mid-plane orthogonal to the rotational axes thereof and looking from rear to front in correspondence with Fig. 2; Fig. 4 is a perspective view to an enlarged scale of an adjustable pressure-regulating outlet valve employed with the compressor of Fig. 1; Fig. 5 is a perspective view of two internal components of the valve of Fig. 4; Fig. 6 is a sectional elevation of the valve of Fig. 4;; Fig. 7 is a right-side elevation of a second embodiment of rotary-vane air compressor in accordance with the invention; Fig. 8 is a plan view of the compressor of Fig. 7; Fig. 9 is a perspective view of the compressor of Fig. 7 showing mainly the front or drive end thereof; Fig. 10 is a rear or non-drive end elevation of the compressor of Fig. 7; Fig. 11 is a vertical sectional elevation of the compressor of Fig. 7, taken in a plane through the rotational axes thereof; Fig. 12 is a vertical part-sectional elevation of the compressor of Fig. 7 viewed from the drive end thereof; and, Fig. 13 is a group of perspective or sectional views of various components and sub-assemblies of the compressor of Fig. 7.

Referring to Figs. 1 to 3 of the drawings, there is shown an air compressor 1 of the rotary-vane type.

The compressor 1 comprises a compressor stator body 5, which is cast as a single block, housing a compressor shaft 3 and secondary shaft 6. Fins 13 are cast on the outer surface of the compressor 1 to promote cooling by heat transfer to the ambient atmosphere.

A single vane 2 is mounted onto the compressor shaft 3 of the compressor 1. The central axis of the compressor shaft 3 is also its centre of rotation.

This shaft 3 can be either directly coupled to or belt-driven by an electric motor or combustion engine (not shown). As the compressor shaft 3 rotates, the vane 2 sweeps through 360 within the annular compression chamber 4 (Fig. 3) formed by the compressor stator body 5, the compressor shaft 3, and compressor end-covers 11, 12. As the compressor shaft 3 rotates, it also drives, through external gears 31, 61, a secondary shaft 6 mounted parallel to and above the shaft 3. The purpose of the secondary shaft 6 is to act as a movable abutment which circumferentially divides the annular compression chamber 4. The secondary shaft or rotatable abutment 6 has a cylindrical periphery with a cut-out 7 which allows the rotating vane 2 to pass in contact with it as shown in Fig. 3.

On the opposite side of the meshed gears 31, 61 is a pulley (not shown) to be belt-driven by a motor (not shown).

The actions of air intake and compression are simultaneous. As the vane 2 rotates clockwise (as viewed in Fig. 3), its trailing or anti-clockwise side faces the intake volume while the leading or clockwise side faces the outlet volume under compression. The inlet volume (closed to outlet) grows with rotation as the vane 2 passes the inlet 8. On the leading (clockwise) side of the vane 2, the outlet volume is simultaneously reduced, causing compression to take place. This outlet volume is open to the outlet 9 (and closed to the inlet 8) until the vane 2 passes the outlet 9 as it moves across through the cut-out 7 in the secondary shaft or movable abutment 6. The equal-tooth-numbered external gears 31, 61 (Fig. 1) ensure both the counter rotation of the shafts 3, 6 and the timing for the rotation vane 2 to pass through the cut-out 7 in the secondary shaft 6.

When the vane 2 is between the outlet 9 and the inlet 8 and in contact with the cut-out 7 in the secondary shaft 6 (as shown in Fig. 3), the chamber 4 is filled with air and is open to both outlet 9 and inlet 8.

During this period, a one-way outlet valve 91 prevents compressed air from backflowing into the chamber 4.

Compression of the working volume in the chamber 4 is repeated as the rotating vane 2 passes the inlet 8 around the major quadrant of the chamber 4 toward the outlet 9. The pressure of delivered air is determined by the setting of the outlet valve 91 and the speed of compressor shaft rotation.

This is to be compared with the gradually reducing volume in an eccentrically rotating vane compressor.

The rotating vane 2 is mounted into the rotating compressor shaft 3 along the shaft axis and between the end-covers 11, 12 of the compressor 1. The vane 2 has sufficient height in the radial direction to ensure contact with the inner wall of the compressor stator body 5. The vane 2 is a composite construction comprising a rigid rectangular holder with slots for springs and pressure plates. When installed and during operation, the springs bear on the ends of the pressure plates thus bringing the plates in contact with the stator 5 and the end-covers 11, 12.

The outlet valve 91 is specially designed; it is constructed to allow the air delivery pressure to be adjusted (see Fig. 6). The outlet valve 91 also acts as a check valve preventing back-flow into the compression.

The compressor 1 of the present invention may be considered to be of the "rotary positive-displacement" type. However, it differs from a conventional rotary positive-displacement machine in that it does not have a "closed-to-outlet, closed-to-inlet" volume which remains constant during rotation. Also, during a part of the rotation, when the vane 2 is in the minor quadrant of the chamber 4 between the outlet 9 and the inlet 8, as particularly shown in Fig. 3, the compression chamber 4 is open to both the outlet 9 and inlet 8. A one-way inlet valve 81 ensures that air induced into the compression chamber 4 cannot leave by the inlet 8, and the one-way outlet valve 91 ensures that there is no back flow of previously compressed air into the compression chamber 4.

Referring now to Figs. 4 to 6, Fig. 4 is a perspective external view to an enlarged scale of the outlet valve 91, detached from the compressor 1 to which it was previously shown operatively connected in Figs. 1 and 2.

Fig. 5 is a perspective view of two internal components of the valve 91, namely an internally-ported shuttle 92 and a ported sleeve 93 which is static in use.

Fig. 6 is a longitudinal median section of the valve 91 showing how the shuttle 92 is slidably mounted within the sleeve 93, the shuttle 92 being loaded by a coiled compression spring 94 so that the valve 91 functions as a combined one-way check valve and pressure regulator.

The compressive force exerted by the spring 94 on the shuttle 92 is adjustable by a screw 95 to vary the setting of the valve 91.

The invention reduces friction and wear between the rotating vane 2 and the stator 5. The compressor 1 is also able to handle a range of fluids besides air.

Because of the nature of the intake and compression stage, it is possible to vary the delivery pressure over a wider desired range by varying the setting of the outlet valve 91.

Important advantages of this invention are therefore: 1. Reduction of mechanical friction by using single vane 2.

2. Centrally rotating shaft 3 instead of eccentrically rotating shaft.

3. Compression of air occurs over a major portion of the shaft's rotation, This makes it possible to obtain a wider range of delivery pressure by changing the setting of the outlet valve 91.

4. This invention is more versatile as it is readily able to handle different types of fluids.

In alternative embodiments (not shown): i A cam shaft with cam lobes and timing gear may be used to time the opening and closing of the inlet and delivery vanes. This cam shaft can be driven by the compressor shaft 3.

ii A sliding vane which is not spring loaded can be used.

iii The vane can be constructed with internal passages for passing a cooling fluid through the compressor shaft.

iv The compressor can be directly coupled to a motor without having to be belt driven.

v A fly-wheel mounted on one end of the compressor shaft may be employed as a means to smooth out energy pulsations.

vi External embodiments can be in the form of closer-spaced, more slender cooling fins on the surface of the compressor body.

Referring now to Figs. 7 to 13, these show a second embodiment of rotary-vane air compressor 100 in accordance with the invention. Figs. 7 to 10 show various external views, respectively right side, top, front and right perspective from above, and rear. Fig.

11 is a vertical section in a plane including both rotational axes (detailed below) to show the internal layout, while Fig. 12 is a part-section in a transverse vertical plane showing further internal details with the vane drive mechanism superimposed. Fig. 13 is a collection of perspective and sectional views of various individual and mutually separated components and sub-assemblies of the compressor 100.

The compressor 100 comprises an assembly of a stator body 102, a sump 104, and end plates 106, topped by a horizontally-divided two-piece manifold block 108. The end plates 106 support a drive shaft 110 on ball bearings, with the shaft 110 extending horizontally through the sump 104 to protrude at either end of the compressor 100. A pulley 112 is mounted on the rear end of the shaft 110 for the compressor 100 to be belt-driven.

Above and axially parallel to the drive shaft 110, the stator 102 defines the radially outer wall of an annular chamber 114 (see Fig. 12). End walls of the annular chamber 114 are defined by the end plates 106, while the inner wall of the chamber 114 is defined by the cylindrical periphery of a rotor hub 116. A fixed abutment 118 depends from the stator 102 into slidingly sealed contact with the rotor hub 116 so as circumferentially to divide the chamber 114.

The rotor hub 116 mounts a diametrally-opposed pair of vanes 120 and 122 which sweep through the annular chamber 114 in a manner detailed below. The hub 116 is an integral part of a rotor shaft 124 which is mounted on ball-bearings in the end plates 106 for rotation about an axis coincident with the longitudinal axis of the annular chamber 114 and parallel to but fixedly offset from the rotational axis of the drive shaft 110.

The construction of each of the vanes 120 and 122 is similar to the construction of the vane 2 in the first embodiment of the present invention.

The forward end of the rotor shaft 124 has a crank arm 126 secured thereto as part of a crank mechanism which is particularly illustrated in Figs. 9, 11 and 12. The forward end of the drive shaft 110 also has a crank arm 128 secured thereto as a further part of the crank mechanism. The crank arms 126 and 128 are coupled by a pivotally-linked connecting rod 130. Although not clearly shown in the drawings (which are schematic), the crank arm 126 has an effective radius from the rotor shaft 124 to its pivotal link with the connecting rod 130 which is just over twice the effective radius of the crank arm 128 from the drive shaft 110 to its pivotal link with the connecting rod 130.Thus the crank mechanism comprising the crank arms 126 and 128 together with the connecting rod 130 functions during sustained unidirectional rotation of the drive shaft 110 to cause the rotor shaft 124 to undergo angular oscillations with an angular magnitude of somewhat less than half of a complete revolution. This angular oscillation of the rotor shaft 124 and of the rotor hub 116 integral therewith causes the vanes 120 and 122 thereon to sweep angularly back and forth in the annular chamber 114 on either side of the fixed abutment 118.

The manifold block 108 contains a pair of spring-loaded one-way poppet inlet valves 132 (only one being visible in Fig. 11 and none being visible in Fig. 12) which allow atmospheric air to be drawn through an inlet filter 134 and admitted to the annular chamber 114, respectively between the anti-clockwise side of the fixed abutment 118 (as viewed in Fig. 12) and the clockwise side of the rotary vane 120, and between the clockwise side of the fixed abutment 118 and the anticlockwise face of the rotary vane 122. Such admission of air occurs alternatively through one of the inlet valves 132 and then through the other inlet valve 132 as the rotary vane 120 circumferentially advances towards the fixed abutment 118 while the other rotary vane 122 simultaneously circumferentially retreats from the fixed abutment 118, and vice versa.

The manifold block 108 further contains a pair of spring-loaded one-way poppet outlet valves 136 (only one being visible in Fig. 11 while both are visible in Fig. 12) which are connected to the annular chamber 114 on either side of the fixed abutment 118 so as alternately to allow air compressed within the annular chamber 114 between either side of the fixed abutment 118 and the two rotary vanes 120 and 122 to be discharged to a common compressor outlet 138.

A force pump 140 is mounted on the side of the sump 104 to have its spring-biassed plunger reciprocated by a cam or eccentric 142 mounted on the drive shaft 110.

In operation, the force pump 140 draws lubricating oil in the sump 104 through its depending inlet 144 and delivers the oil under pressure through a branched lubricant delivery pipe 146 to the non-drive or rear end of the rotor shaft 124 (see Fig. 11) and to the manifold block 108 (see Figs. 7, 8, 9 and 10). Surplus oil in the annular chamber 114 drains back into the sump 102 through a drain channel 148 (see Fig. 12).

The compressor 100 may be fitted with an adjustable pressure-regulating outlet valve in the form of the combined one-way check valve and pressure regulator 91 described above with reference and as shown in Figs. 4 to 6.

Modifications and variations in the above-described arrangements can be adopted without departing from the scope of the invention as defined in the appended claims.

Claims

1. A rotary-vane compressor for compressing a working fluid, said compressor comprising a stator having an annular chamber with a longitudinal axis, a vane means rotatably mounted for circumferential movement in said annular chamber about a rotation axis coincident with the longitudinal axis of said annular chamber, an abutment means circumferentially dividing said annular chamber, an inlet valve means for admitting working fluid to said annular chamber, an outlet valve means for discharging working fluid from said annular chamber, and vane drive means for rotatably driving said vane means in said annular chamber such that the vane means undergoes cyclic variation of its circumferential separation from the abutment means whereby working fluid is cyclically drawn through the inlet valve means into said annular chamber between the vane means and the abutment means, compressed, and discharged through the outlet valve means from said annular chamber.

2. A compressor as claimed in Claim 1 wherein said abutment means is a movable abutment means, the abutment means being a rotary abutment rotatable about an axis parallel to and offset from the the rotation axis of the vane means, the rotary abutment being coupled to said vane drive means to be rotatably driven synchronously with the vane means, the rotary abutment having a peripheral abutment surface which is cylindrical between one or more peripheral cut-outs, and the axial offset of the rotary abutment and its phase angle with respect to the vane means being such that in operation of the compressor, said peripheral abutment surface divides the annular chamber and said one or more peripheral cut-outs permit circumferential passage of the vane means during unidirectional rotation thereof.

3. A compressor as claimed in Claim 2 wherein the compressor has a single movable abutment co-operating with a single radially projecting vane, the vane drive means causing unidirectional rotation of the vane in operation of the compressor.

4. A compressor as claimed in Claim 1 wherein said abutment means is a fixed abutment means, and said vane drive means is such that the vane means is rotably driven in angular oscillations.

5. A compressor as claimed in Claim 4 wherein said angular oscillations are substantially less than a complete revolution in magnitude.

6. A compressor as claimed in Claim 5 wherein the compressor has a single fixed abutment co-operating with a diametrically opposed pair of radially mounted vanes, the vane drive means angularly oscillating the vanes through a rotational angle of less than half of a complete revolution in operation of the compressor.

7. A compressor as claimed in Claim 6 wherein said vane drive means comprises a crank drive mechanism having a driven crank arm rotationally secured to the vane means and linked by a pivotally coupled connecting rod to a unidirectionally rotatable drive crank arm, said driven crank arm having a radius more than twice as great as the radius of the drive crank arm.

8. A compressor as claimed in any preceding claim, wherein at least the inner wall of the annular chamber is formed by the cylindrical periphery of a rotatable hub on which the rotatable vane means is mounted.

9. A compressor as claimed in any preceding claim, wherein said inlet valve means and said outlet valve means each comprise a spring-biassed poppet valve.

10. A compressor as claimed in any of Claims 1 to 8, wherein said inlet valve means and said outlet valve means each comprise a respective cam-operated valve, the cam or cams which operate said valves being driven synchronously with the rotating vane means in operation of the compressor for operation of the respective valves at predetermined angular positions of the vane means.

11. A compressor as claimed in any preceding claim, wherein said working fluid comprises a compressible gas.

12. A compressor as claimed in Claim 11, wherein said compressible gas is air.

13. A compressor as claimed in any of Claims 1 to 10, wherein said working fluid comprises an incompressible liquid.

14. A compressor as claimed in Claim 13, wherein said incompressible liquid is oil.

15. A compressor as claimed in Claim 13, wherein said incompressible liquid is water.

16. A rotary-vane compressor substantially as hereinbefore described with reference to Figs. 1, 2 and 3 of the accompanying drawings.

17. A rotary-vane compressor substantially as hereinbefore described with reference to Figs. 7 to 13 of the accompanying drawings.

18. A rotary-vane compressor as claimed in Claim 16 or Claim 17, in combination with an adjustable pressure regulating outlet valve substantially as hereinbefore described with reference to Figs. 4, 5 and 6 of the accompanying drawings.