GB2188678A - Rotary compressor - Google Patents

Description

GB2188678A 1 SPECIFICATION According to one aspect of this invention a

rotary compressor comprising: a stator defin "Commapressor" rotary compressor ing a generally cylindrical compression cham ber, an inlet zone into said chamber and an THIS INVENTION relates to rotary compresoutlet zone from said chamber; a plurality of sors and more particularly provides a com- substantially indentically shaped intermeshing pressor in which elements slide against one elements, said elements being fully intermesh another during a compression cycle and form able to form a generally cylindrical rotor and a rotor assembly. being movable with respect to one another Numerous configurations exist for rotary 75 upon rotation within said chamber to form an type compressors. A common configuration is enlarged working volume adjacent said inlet referred to as a rotary vane type compressor zone and a reduced working volume adjacent and includes a stator defining a chamber said outlet zone, and means for rotating said within which a rotar rotates. The rotor is elements within said chamber.

affixed to a shaft driven by. a motor. The rotor 80 According to a second aspect of this inven- and the chamber walls are generally cylindri- tion a rotary compressor comprising: a plural cal, the chamber being larger than the rotor, ity of similarly shaped elements meshable to and the rotor rotates eccentric to and against form a generally cylindrical rotor and alter the chamber wall. The rotor in such machines nately extendable to define an enlarged work- includes blades of rods which extend out- 85 ing volume and a reduced working volume; a wardiy from and retract against the rotor to stator defining a generally cylindrical compres form variable volume compression zones. sion chamber having an inlet zone and an out Typical of such designs is that disclosed in let zone, said elements being rotatable within U.S. Patent No. 4,118,160 which includes a said chamber and cooperable with an inside rotor having rectractable blades at its peri- 90 cylindrical wall of said chamber and said inlet phery mounted to pivot about pins. The rotor zone and outlet zone to receive a working is mounted on a drive shaft in an eccentric fluid from said inlet zone upon said elements relation to the axis of a surrounding stator. defining said enlarged working volume and to Upon rotation of the rotor the blades extend discharge said working fluid to said outlet outwardly from, and then retract into, the 95 zone upon said elements defining said reduced body of the rotor. Generally similar configura- working volume.

tions are shown in U.S. Patent Nos. According to a third aspect of this invention 4,415,322 and 1,995,755. a rotary compressor comprising: a stator de U.S. Patent No. 4,396,365 discloses a ro- fining an annular chamber having a radius of tary vane type compressor having a rotor with 100 curvature and having a radially positioned per generally radially extending liners housing ipheral inlet zone and a radially positioned per vanes which extend into and out of the liners ipheral outlet zone; a plurality of identically upon rotation of the rotor within a cam housshaped elements, said elements being mesha ing or stator. Similar rotary sliding vane confi- ble to form a generally cylindrical rotor having gurations are disclosed in U.S. Patent No. 105 a radius smaller than said radius of curvature 3,917,438. and being slidable with respect to one another Such structures can be improved upon. For to define an enlarged working volume adjacent example, the number and type of components said inlet zone and a reduced working volume affixed to the rotor can be reduced. Addition- adjacent said outlet zone; and means for ro ally, the unloaded horsepower and startup tor- 110 tating said elements within said chamber.

que of such machines tends to be relatively According to a fourth aspect of this inven high, and can be lowered. The relatively high tion, a rotary compressor comprising: a rotata unloaded power requirements and startup tor- ble shaft; a plate affixed to rotate with said ques result from compression continuing dur- shaft; a plurality of commonly shaped ele ing the unloaded cycle as such structures have 115 ments contiguously arranged and intermesha fixed, built in compression ratios which are a ble to form a generally cylindrical rotor confi function of the relationship of the inlet and guration, said elements being pivotably affixed discharge ports. with respect to said plate to slidably reposi Some of the existing configurations can also tion and cycle between a reduced configura cause a high degree of wear between the ex- 120 tion and an expanded configuration; a stator tensions from the rotor and the stator due to surrounding said elements and defining a frictional forces, whch can be reduced. Radial generally cylindrical compression chamber ec vane type units also are limited in the amount centric with respect to said shaft, said cham of vane extension beyond the basic rotor cir- ber having an inlet zone adjacent said ele cumference because of bending moments inments in said expanded configuration and an duced on the vanes. This limits the stator outlet zone adjacent said elements in said re bore size and displacement for a given rotor duced configuration.

and stator size. According to a fifth aspect of this invention It is desirable to improve upon these rotary an element of a rotor for use in a rotary com compressor structures. 130 pressor, said element comprising an axially ex- 2 GB2188678A 2 tending body having in cross section in series which:

a first convex section of radius r, a second Figure 1 is an end view of rotary compres concave section also of radius r, and a third sor elements in accordance with an embodi convex section of radius R, R being greater ment of the invention arranged in an inter than r. 70 meshed configuration; In summary, therefore, this invention pro- Figure 2 is a perspective view of a rotary vides a rotary type compressor including a compressor element in accordance with an stator defining a compression chamber. The embodiment of the invention; compression chamber is generally cylindrical, Figure 3 is a cross sectional view of a ro and includes an inlet and an outlet. The inlet 75 tary compressor in accordance with the inven and outlet can be positioned radially at the tion, with compressor elements in an inward, circumferential periphery of the chamber, or closed configuration; axially at the ends of the chamber. Figure 4 is a cross sectional view, similar to In specific embodiments of the invention the Fig. 3, but without a central protrusion, show following features may be incorporated. 80 ing the compressor elements in an outward, A plurality of elements are positioned and open configuration; configured to rotate eccentrically within the Figure 5 is a longitudinal cross sectional chamber. The elements are identical in periph- view of an embodiment of a rotary compres eral cross section and are similar in shape to sor in accordance with the invention; a comma. Each element includes an enlarged 85 Figure 6 is a cross sectional view of a ro end or head portion that tapers to a reduced tary compressor having an actuator to inter end or tail portion. The enlarged end is a con- mesh the compressor elements; and vex section sized as a radius r, which con- Figure 7 is a perspective view of a com nects to a concave section also of radius r. pressor element having a camming slot inter- The sections are joined by a convex section 90 acting with an actuator.

of radius R which is larger than the radius r. Referring to Fig. 1 there is shown an end In preferred form the relationship between the view of four compressor elements 10 inter radii is defined by R=r+r/sin(180/n), where n meshed to form a cylindrical configuration.

is the number of elements. The assembly of elements is herein referred to The elements are intermeshable so as to 95 as a rotor assembly 12. The formed generally form a rotor assembly having a generally cylindrical rotor assembly is of radius R (Figs.

cylindrical cross section and a radius equal to 2 and 3), taken from a centerpoint 8. The R. The elements are pivotable as they rotate elements 10 define a central opening 14. The within the chamber. During normal operation elements are part of a rotary compressor adjacent elements cycle between an inward 100 designated generally by reference numeral 6.

position in which the elements are substan- Apertures 16 which extend partially into each tially intermeshed and an outward position element 10 are shown. In Fig. 1, and aper where the adjacent elements are pivoted far- tures 16 which extend fully through each ele ther out of the intermeshed configuration. In ment 10 are shown in Fig. 2 and 3.

the region of the outward positioning an en- 105 Fig. 2 shows a single element 10. The aper larged working volume is defined which re- ture 16 provides a region about which the ceives working fluid from the chamber inlet. element 10 pivots during operation. The per As the rotation and pivoting of the elements ipheral cross section of each element 10 is continue, the elements move toward the in- shaped as a comma, having an enlarged head ward position, defining a reduced working vol- 110 portion 18 which tapers to a reduced tail por ume which communicates with the chamber tion 20. The element is defined by three radii.

outlet. The first, a radius of length r, defines the In a preferred form the compressor includes head portion 18 and extends from a center an actuator to intermesh all of the elements point 22. It defines the head portion by a into the substantially cylindrical configuration. 115 convex arc between a point -a- and a point In that configuration the closely assembled ---b-. The second, a radius also of length r, elements rotate within the chamber without extends between point -b- and a point "c" creating any significant compression of work- and defines a concave segment. Point b is a ing fluid. This allows unloaded operation with smooth inflection point between the first con a low power requirement, and also provides a 120 vex segment ab and the second concave seg configuration allowing a low torque startup. ment bc. Thus, point b geometrically repre In preferred form the elements are identical sents the point of touching of two adjacent, in cross section and can thus be extruded or nonintersecting cicles of equal radius. For fab otherwise formed in axial bars which can be ricction purposes there will be a small radi cut to required lengths. 125 used edge at point "c". The third, a radius R, The advantages, nature and additional fea- extends between point "c" and point -a- and tures of the invention will become more ap- defines another convex segment ca. There is parent from the following description, (which a smooth transition from radius R to radius r is by way of example only) taken in connec- at point "a". Thus, geometrically a tangent tion with the accompanying drawings, in 130 line to the circle of radius r at point -a- is 3 GB2188678A 3 the same as a tangent line to the circle of as the elements 10 rotate about within the radius R at point---a-. R is greater than r. compression chamber 26, and pivot about Preferably the relationship between R and r is their center points 22, an enlarged working defined by the equation: volume 36 (Fig. 4) is formed in the region 70 adjacent the inlet zone 32 and a reduced r working volume 38 is formed in the region R=r+ adjacent the outlet zone 34. The working vol ume is defined among two adjacent elements SIN - 10 and a wall 40 of the compression chamber n 75 26. The working volume cycles between a maximum adjacent the inlet zone 32 and a where n is the number of commonly shaped minimum adjacent the outlet zone 34.

elements forming a rotor assembly. The num- In Fig. 5 there is shown one preferred ar ber of elements 10 forming the rotor as- rangement for positioning and rotating the ele- sembly 12 can vary from a minimum of two, 80 ments within the compression chamber. Aper upwardly. However, the size of an inlet 32 tures 16 of the elements 10 extend t ' he full and a discharge 34 port and the amount of axial length of the elements. Positioned internal compression desired of a given com- through the apertures 16 are pivot pins 42.

pressor suggest that a compressor of the The pivot pins 42 are affixed between a rear type disclosed have between four and eight 85 end plate 44 and a front end plate 46, each elements 10. Six elements are preferred. The having containing cavities 48. The pivot pins greater the number of elements 10, the smal- 42 preferably are fixed relative to the end ler is the size of each and the smaller is the plates 44, 46. Many alternative attachment displacement for a given rotor assembly and configurations will be readily apparent. For stator diameter, and the greater is the central 90 example, the pivot pins may only extend par nonworking area 14. In the case of a six ele- tially into the elements 10 and can be used at ment rotor assembly, a central circular bar one or both ends. The pivot pins 42 can also touching each element 10 will have the same be integrally affixed at one or both ends to radius r as each element 10. the elements 10, and rotate in a correspond- As shown in Figs. 1 and 3, the center point 95 ing end plate cavity 48.

22 of the convex head portion 18 of each In the configuration shown in Fig. 5, the element 10 lies at the intersection of two ad- rear end plate 44 is affixed to a shaft 50 jacent sides of a regular polygon 24 having which comprises a portion of the structure for the same number of sides as the number of rotating the elements 10. The shaft 50 is elements 10 forming the rotor assembly 12. 100 aligned along the longitudinal axis 52. The The inflection point -b- lies at the point of shaft 50 is driven by a motor (not shown).

intersection of the regular polygon 24 with the The end plate 44 includes a cylindrical protru periphery of an element 10 when the ele- sion 54 contiguous with or closely spaced ments 10 are fully intermeshed to form the from the surrounding elements 10 to reduce a generally cylindrical configuration. 105 potential leakage path. The front end plate 46 As shown in Fig. 3, the elements 10 are includes a passage 56 through which an actu housed within a compression chamber 26 of a ator 58 passes. The actuator 58 includes ex stator 28. The compression chamber 26 is tensions 60 and the compressor 6 includes preferably of cylindrical configuration defined means for axially moving the actuator 58 such in cross section by a circle of radius S having 110 as a pneumatic, hydraulic or electric actuating a center point 30. The radius S of the stator controller 62.

compression chamber 26 is larger than the As shown best in Figs. 6 and 7 the exten radius R of the cylindrical rotor assembly 12. sions 60 are positioned within grooved sec The center point 8 of the rotor assembly 12 tions 64 of the elements 10 which sections is eccentric with respect to the center point 115 64 have a camming surface 66. The exten of the compression chamber 26. The cen- sions 60 and camming surface 66 interact ter point 8 lies along a longitudinal axis 52 of such that upon axial movement of the actuator the assembled elements and the center point 58, the extensions 60 are forced against the lies along a longitudinal axis 53 of the camming surfaces 66 causing the elements 10 stator compression chamber 26. 120 to mesh into the configuration of the generally The stator 28 also defines the inlet zone 32 cylindrical rotor 12. Other means for inter and the outlet zone 34 is fluid communication meshing the elements 10 are equally possible.

with the compression chamber 26. The zones Referring particularly to Figs. 4 and 6, dur can be radially or axially oriented, and many ing operation the elements 10 are rotated differing port configurations are equally pos125 within the compression chamber 26, the pre sible. Fig. 3 shows the extent of an axial inlet ferred direction being indicated in Fig. 1. Typi zone 32 through which working fluid is suc- cal operating speeds are 1800 or 3600 rpm.

tioned into the compression chamber 26 and At this rotational velocity a centrifugal force at an axial outlet zone 34 through which corn- the tail portion 20 tends to pivot the elements pressed fluid is discharged. During operation, 130 10 outwardly and out of the intermeshed 4 GB2188678A 4 cylindrical configuration. The axis of rotation a cycle is smooth.

52 of the elements 10 is positioned within the With particular reference to Fig. 6, it will chamber 26 such that the elements 10 are now be apparent that a compressor in accor allowed to pivot outwardly a greater distance dance with the invention allows unloading adjacent the inlet zone 32 and are more re- 70 merely by placing the elements 10' in the strained by the wall 40 of the chamber 26 generally cylindrical, fully intermeshed configu adjacent the outlet zone 34. Thus, while the ration, in which no compression takes place.

centrifugal forces tend to drive the elements A check valve (not shown) is preferably incor outwardly, their position is restrained by porated acting in communication with either the chamber wall, or an extension of the wall 75 the inlet zone 32 or outlet zone 34 to prevent or some other mechanical restraint such as back flow through the compression chamber those acting as a camming surface against the when operating in the unloaded configuration. f elements 10. Other cam or gear structures for In this configuration only enough driving restraining or guiding the elements during rota- horsepower to overcome frictional restraints is tion can also be used. 80 required. This configuration is also preferred As rotation passed the inlet zone 32 contin- during startup, requiring a relatively low star ues, the forces tending to drive the elements tup torque.

outwardly are also counteracted by the in- The parts of a compressor in accordance creasing pressure differential across the ele- with the invention can be composed of num ment. A compressible working fluid enters the 85 erous materials including those typically uti enlarged working volume 36 from the inlet lized on sliding vane and rotary screw com zone 32 and is compressed into a smaller pressors. Particularly for oil free operation, the volume and a higher pressure as the elements elements 10 may be comprised of self lubri rotate through the compression cycle. cating types of materials. It will be recognized There is a higher pressure acting on the ex- 90 that since the cross sectional peripheral shape posed convex surface ca than on the exposed of each of the elements 10 of a compressor and smaller concave surface bc. This counter- of the type disclosed is identical, fabrication acting force tends to offset a portion of the can include an elongated structure cut to the centrifugal force and reduces possible wear desired axial length of each element 10. Man from the frictional interaction of the tail of the 95 ufacture by extrusion or plastic injection mold elements 10 and the compression chamber ing is possible, as is consideration of lami wall 40. nates, sintered metals and ceramics. The den In addition, an incompressible fluid may be sity of the material selected for manufacture present as in, for example, start up or other of the elements 10 will have an affect upon conditions of oil injected compressors or refri- 100 the centrifugal force exerted upon the tail por geration compressors. The presence of an intion 20 of each element. It may therefore be compressible liquid in the volume between ad- desirable in certain designs, considered in con jacent elements 10 will create forces tending junction with, for example, rotor assembly size to cause the elements to pivot against the and rotational speed, to vary the material den rotational direction to relieve the pressure 105 sity across the cross section of the element without detriment to the compressor. or its to enhance or retard the outward force.

operation. Many rotary vane compressor systems uti Operation in the opposite direction from that lize a stator chamber shaped somewhat differ noted as preferred is also possible. In this ently than a cylindrical configuration. It will be case the force from the pressure differential 110 apparent that the compressor structures dis across an element 10 will be added to the closed herein are compatible with such confi centrifugal force acting on the element, but gurations. Many other modifications are self-reHeving action as noted above will not be equally possible without departing from the obtained with the presence of a liquid. spirit of the disclosure. It therefore is intended

The compressed working fluid is discharged 115 that within the scope of the appended claims, to the outlet zone 34. The axis of rotation 52 the description and Figures be taken as illus is positioned so that a portion 40' of the trative, and not in a limiting sense.

chamber wall is at the radius R, the radius of

Claims (1)

1. the cylindrical rotor configuration, to maintain CLAIMS a portion of an

   element 10 adjacent the wall 120 1. A rotary compressor comprising: a sta as a separation between the outlet zone tor defining a generally cylindrical compression 34 and the inlet zone 32. A segment of the chamber, an inlet zone into said chamber and compression chamber wall between the inlet an outlet zone from said chamber; a plurality zone and outlet zone can be contoured to the of substantially indentically shaped intermesh- radius R to enhance the segregation. 125 ing elements, said elements being fully inter It can be seen from the Figures that the meshable to form a generally cylindrical rotor elements nest or intermesh along the surfaces and being movable with respect to one defined by the convex and concave portions another upon rotation within said chamber to of the same radius r. The sliding and pivoting form an enlarged working volume adjacent movement between adjacent elements during 130 said inlet zone and a reduced working volume GB2188678A 5, adjacent said outlet zone, and means for ro- wherein each said element includes an axially tating said elements within said chamber. extending slot and wherein said meshing 2. The rotary compressor of claim 1 means comprise a plurality of extensions, said wherein said elements are fully intermeshable extension each being engageable with a re to form a generally cylindrical rotor of a radius 70 spective slot.

   R, said radius R being smaller than a radius S 15. The rotary compressor of claim 14, of said generally cylindrical compression cham- wherein each said extension is affixed to an ber. axially movable actuator, and wherein each 3. The rotary compressor of claim 1 or 2, said slot is shaped as a camming surface such wherein each said substantially identically 75 that upon axial motion of said actuator said shaped element is shaped in cross section as elements are forced to mesh into the configu a comma. ration of said generally cylindrical rotor.

   4. The rotary compressor of claim 1, 2 or 16. A rotary compressor comprising: a plu- 3, wherein the cross sectional shape of each rality of similarly shaped elements meshable to said shaped element comprises in series a 80 form a generally cylindrical rotor and alter first convex section of radius r, a second con- nately extendable to define an enlarged work cave section also of radius r, and a third con- ing volume and a reduced working volume; a vex section of radius R, R being greater than stator defining a generally cylindrical compres r. sion chamber having an inlet zone and an out- 5. The rotary compressor of claim 4, 85 let zone, said elements being rotatable within wherein said shaped elements are intermesha- said chamber and cooperable with an inside ble to form a generally cylindrical rotor of ra- cylindrical wall of said chamber and said inlet dius R. zone and outlet zone to receive a working 6. The rotary compressor of claim 4 or 5, fluid from said inlet zone upon said elements wherein said first convex section defines an 90 defining said enlarged working volume and to enlarged head portion which tapers to a redischarge said working fluid to said outlet duced tail portion defined by said second con- zone upon said elements defining said reduced cave section and said third convex section. working volume.

   7. The rotary compressor of claims 4 to 6, 17. The rotary compressor of claim 16, wherein n is the number of said shaped ele- 95 wherein each said similarly shaped element is ments and wherein shaped in peripheral cross section as a comma.

   r 18. The rotary compressor of claim 16 or R=r+ 17, wherein each said similarly shaped ele 180 100 ment comprises in series a first convex sec SIN - tion of radius r, a second concave section n also of radius r, and a third convex section of radius R, R being greater than r.

   8. The rotary compressor according to any 19. The rotary compressor of claim 17, one of the preceding claims, wherein each 105 wherein n is the number of said similarly said element is pivotably mounted to a re- shaped elements and wherein spective pivot pin.

   9. The rotary compressor according to any r one of the preceding claims, wherein said ro- R=r+ tating means comprises a rotatable back end 110 180 plate affixed to said pivot pins. SIN - 10. The rotary compressor of claim 9, n wherein each said pivot pin extends axially through its respective element and wherein 20. A rotary compressor comprising: a said rotating means comprise a rotatable front 115 stator defining an annular chamber having a end plate engaging one extent of each said radius of curvature and having a radially posi pivot pin and wherein said rotatable back end tioned peripheral inlet zone and a radially posi plate engages the other extent of each said tioned peripheral outlet zone; a plurality of pivot pin. identically shaped elements, said elements be- 11. The rotary compressor of claim 10 120 ing meshable to form a generally cylindrical wherein at least one of said plates is affixed rotor having a radius smaller than said radius to a rotatable shaft. of curvature and being slidable with respect to 12. The rotary compressor of claim 11 one another to define an enlarged working wherein said shaft is concentric with said volume adjacent said inlet zone and a reduced formed generally cylindrical rotor. 125 working volume adjacent said outlet zone; and 13. The rotary compressor according to means for rotating said elements within said any one of the preceding claims, further com- chamber.

   prising means for meshing said elements to 21. The rotary compressor of claim 20, form said generally cylindrical rotor. wherein the cross sectional shape of each 14. The rotary compressor of claim 13, 130said similarly shaped element comprises in 6 GB2188678A 6 series a first convex section of radius r, a second concave section also of radius r, and r a third convex section of radius R, R being R=r+ greater than r. 180 22. The rotary compressor of claim 20, 70 SIN - wherein n is the number of said identically n shaped elements and wherein 29. The element of claim 28, wherein n r equals 6.

   R=r+ 75 30. Any novel feature or combination of features disclosed herein.

   SIN - n Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd. Dd 8991685, 1987.

   Published at The Patent Office. 25 Southampton Buildings, 23. A rotary compressor comprising: a ro- London, WC2A l AY, from which copies may be obtained.

   tatable shaft; a plate affixed to rotate with said shaft; a plurality of commonly shaped elements contiguously arranged and intermeshable to form a generally cylindrical rotor confi- guration, said elements being pivotable affixed with respect to said plate to slidably reposition and cycle between a reduced configuration and an expanded configuration; a stator surrounding said elements and defining a generally cylindrical compression chamber eccentric with respect to said shaft, said chamber having an inlet zone adjacent said elements in said expanded configuration and an outlet zone adjacent said elements in said re- duced configuration.

   24. The rotary compressor of claim 23, wherein the cross sectional shape of each said similarly shaped element comprises in series a first convex section of radius r, a second concave section also of radius r, and a third convex section of radius R, R being greater than r.

   25. The rotary compressor of claim 23 wherein n is the number of said similarly shaped elements and wherein r R=r+ 180 SIN - n 26. An element of a rotor for use in a rotary compressor, said element. comprising an axially extending body having in cross section in series a first convex section of radius r, a second concave section also of radius r, and a third convex section of radius IR, R being greater than r.

   27. The element of:claim 26, wherein said element is shaped in cross section as a comma.

   28. The element of claim 26, wherein n is an integer between 4 and 8 inclusive and wherein