US3671154A - Epitrochoidal compressor - Google Patents

Abstract

A COMPRESSOR OF THE EPITROCHOIDAL ROTOR TYPE HAS A ROTOR WITH N HOLLOW LOBES AND A STATOR HOUSING WITH N+1 LOBES, A COMMON DISCHARGE AND INLE SIDE PLATE ON ONE SIDE OF THE ROTOR AND AN INLET SIDE PLATE ON THE OPPOSITE SIDE OF THE ROTOR LOADED AGAINST THE ROTOR BY FLUID PRESSURE LED FROM THE DISCHARGE CAVITY OF THE COMPRESSOR.

Description

June 20, 1972 w. H. KOLBE ET L EPITROCHOIDAL COMPRESSOR 3 Sheets-Sheet 1 Filed Oct. 8, 1970 BY (/Zzro 511211 1' 9 ATTORNEY June 20, 1972 w, KQLBE ET AL EPITROCHOIDAL COMPRESSOR 3 Sheets-Sheet 2 Filed Oct. 8, 1970 ATTORNEY June 20, 1972 w, KQLBE ET AL EPITROCHOIDAL COMPRESSOR 3 Sheets-Sheet 5 Filed Oct. 8, 1970 BY Taro 5 ATTORNEY United States Patent US. Cl. 41861 6 Claims ABSTRACT OF THE DISCLOSURE A compressor of the epitrochoidal rotor type has a rotor with N hollow lobes and a stator housing with N +1 lobes, a common discharge and inlet side plate on one side of the rotor and an inlet side plate on the opposite side of the rotor loaded against the rotor by fluid pressure led from the discharge cavity of the compressor.

This invention relates to an epitrochoidal compressor, and more particularly to an epitrochoidal rotor type refrigerant compressor for use in automobile air conditioning systems and the like.

A large number of problems present themselves in the design and construction of refrigerant compressors of the type which are adapted to be driven by a car engine either continuously or intermittently through a clutch. These problems result from the fact that the compressor is required to operate throughout a very wide speed range while requiring a low drive input torque throunghout this speed range. The problems are multiplied by the fact that the amount of space available for the compressor is very limited and all of the parts must be of lightweight construction and arranged in a small casing.

It is, therefore, the principal object of this invention to improve such as refrigerant compressor for use in air conditioning automobiles wherein the compressor is lightweight and occupies a minimum amount of space.

A further object of the invention is to improve such a refrigerant compressor whereby the compressor has an improved refrigerant inlet and discharge arrangement and an improved seal arrangement for the working chambers of the compressor.

These and other objects of the invention are obtained by means of an epitrochoidal compressor, the compression chamber of which consists of a five-lobed epitrochoidal rotor, a stationary housing with six-lobed inner contours, stationary vanes held in the slot in the housing and spring loaded against the rotor, and side plates on both sides of the rotor. The rotor turns on the eccentric of a drive shaft, and its angular location relative to the vanes is determined by an internal-external timing gear set; the inner gear with external teeth is attached to the rotor, and the outer gear with inner teeth is part of one of the stationary side plates of the compressor. To insure a tight seal on both sides of the rotor, the side plates are loaded against the sides of the rotor by fluid pressure led from the discharge cavity of the compressor. The suction fluid enters into the compression chambers through the inlet port openings provided in the side plates on opposite sides of the rotor with communication through the hollow lobes of the rotor itself.

For a better under standing of the invention, as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a view in vertical section of the compressor of the invention;

FIG. 2 is a view in vertical section taken along line 2-2 of FIG. 1;

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FIG. 3 is a view in vertical section taken along line 33 of FIG. 1;

2 FIG. 4 is a sectional view taken along line 44 of FIG.

FIG. 5 is a view in vertical section taken along line 5-5 of FIG. 1;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5; and

FIG. 7 is a view in vertical section taken along line 77 of FIG. 1.

Referring now to the drawings, in which a preferred embodiment of the invention is shown, the compressor includes a stationary housing consisting of a central cylinder housing or stator 10, side plates 11 and 12, rear head or casing 13 and front head or casing 14, the rear head and front head being secured to the stator by band clamps 15. A rotor, generally indicated 16, is mounted in the stator, as described in detail hereinafter, to form with it a number of working or compression chambers.

The rotor 16 has an epitrochoidal profile with N lobes and rotates eccentrically in the stator 10 having N+1 lobed inner contours. Although the number of lobes on the epitrochoidal rotor, which determines the number of compression chambers, can be chosen at will, in the preferred embodiment of the compressor disclosed, six working chambers are used to provide for low drive torque variation during each shaft revolution.

Thus, the rotor 16 is in the form of a five-lobed epitrochoidal rotor while the stator 10 has a six-lobed inner contour with the shape relationship of the rotor and stator being such as to provide facing surfaces that define upon relative movement of the rotor with respect to the stator, six variable volume working chambers. Sealing vanes 17 are positioned in longitudinal grooves in the stator 10 and are biased into engagement with the peripheral surface of the rotor 16 by vane springs 18 to provide seals between the working chambers. Although the vanes 17 are biased radially inward by spring 18 there is little or no movement of the vanes in and out of the slots as the rotor 16 rotates due to the geometric configuration of the epitrochoidal rotor. The compressor can thus be operated over a broad operating speed range because of little or no vane movement and no centrifugal force on the vanes to effect contact load.

As shown, rotor 16 includes a rotor body 20, with a gear hub 21 secured by one or more pins 22 to one side thereof a rotor hub 23 secured to the opposite side by a retaining ring 24 positioned in suitable external and internal annular grooves formed in the rotor hub 23 and rotor body 20, respectively. This rotor structure is mounted by bearings 25 on the spaced eccentric portion 26 of the shaft 27 which in turn is journaled by bearings 28 housed in the rear head 13 and front head 14, a thrust washer 30 being positioned in the rear head 13 to butt against the left-hand end of the shaft 27, as seen in FIG. 1. Intermediate the spaced eccentric portions 26, a counterweight 31 is secured to the shaft 27 as by being electron beam welded thereon.

Shaft 27 is suitably sealed in front head 14 by a conventional shaft seal 32 and is driven by a conventional magnetically operated pulley and clutch assembly 33 connected by belt 34 to, for example, a drive pulley on an automobile engine, not shown.

As the shaft 27 is rotated in the direction of the arrow, as shown in FIG. 2, the rotor 16 turns in the opposite direction on eccentric portions 26 thereof and its angular velocity relative to the vanes 17 is determined by an inner gear with external gear teeth 35 provided on gear hub 21 and an outer gear with inner gear teeth 36 provided on side plate 11. The side plate 11 is fixed to stator 10 and rear head 13 by dowel pins 37 as seen in FIGS. 3 and 5.

In the embodiment shown, shaft 27 rotates at five times the speed of the rotor 16.

Ingress and egress of fluid to and from the working chambers s controlled by movement of the rotor 16. relative to the stator 10 and to the end plates 11 and 12, the latter being in contact with the side faces of the rotor, being made slightly wider than stator 10 to insure sealing contact between the rotor 16 and side plates 11 and 12. Both the side plates 11 and 12 are provided with suitable inlet ports adapted to be placed in communication with the working chambers, as described in detail hereinafter, and side plate 11 is provided with discharge ports in its outer periphery for the discharge of fluid from the working chamber during the compression cycle.

Both the rear head and the front head are provided with annular inlet chambers 40 and 41, respectively, the chamber 40 being in communication with a common inlet 42 in the rear head 13 having a suction screen 43 positioned therein. Fluid from the inlet chambers 40 and 41 can enter the working chambers during the suction stroke through curved inlet ports 44 and 45 in side plates 11 and 12, respectively. As seen in FIGS. 1 and 2, the inlet ports 44 on the rotor side of side plate 11, of suitable configuration as described hereinafter, merge into elongated arcuate apertures positioned circumferentially the gear teeth 36 on the outboard or left-hand face of the side plate 11 as seen in FIG. 1. Side plate 12, which is centrally apertured, has its inlet ports 45 formed as a continuation of this central aperture. Inlet fluid can flow from inlet chamber 40 to inlet chamber 41 through the inlet ports 44 and 45 which are adapted to be in communication with each other through channels 46 provided in each of the lobes of the rotor 16. As seen most clearly in FIGS. 2 and 3, the contour of the inlet ports 44 and 45 is such as to effect proper inlet port closing timing while maintaining maximum mean port opening area, as these inlet ports are opened and closed by the side walls of the lobes of the rotor 16. With this arrangement each working chamber is provided with a double inlet port, one on each side of the working chamber through side plates 11 and 12 from opposed inlet chambers 40 and 41, respectively, continually in communication with each other by means of the channels 46 in the lobes of rotor 16.

As fluid is compressed in each working chamber, it is discharged therefrom through the discharge ports 47 in side plate 11. As seen in FIGS. 1 and 5, the discharge ports 47 are positioned to receive fluid from each working chamber as a lobe of the rotor is at top dead center therein, with the discharge ports normally closed by reed valve 48 seating against the outboard or left-hand face of the side plate as seen in FIG. 1. As shown in FIGS. and 6, each reed valve serves two discharge ports 47, the reed valve being secured intermediate its ends by a rivet stud 51 to the side plate 11, with a curved retainer 52 positioned over the reed valve to limit outward deflection of the ends of the reed valve. Alignment of these assemblies is maintained by bent-over tabs 53 of the retainer 52 being engaged in suitable apertured slots 54 formed in the side plate 11.

Fluid discharged through the discharge ports 47 enters an annular discharge chamber 55 in rear head 13 which is in communication with a common discharge conduit 56 therein, as seen in FIG. 4. Discharge chamber 55 is effectively sealed from inlet chamber 40 by means of O- ring seal 57 positioned in a suitable annular groove in the rear head, the seal 57 being sandwiched between the side plate 11 and rear head 13. A second annular seal 58 is positioned against the chamfered outer peripheral edge of side plate 11 to be in sealing engagement with side plate 11, rear head 13 and stator 10.

As previously mentioned rotor 16 is made wider than stator so that the sides of the rotor can be effectively sealed by the side plates 11 and 12. To effect this seal control, side plate 12, although fixed against rotation relative to stator 10 and front head 14 by dowel pins 37,

4 as seen in FIGS. 2 and 7, is moveable axially with respect to the axis of rotation of shaft 27. Side plate 12 is loaded against the side of rotor 16 to place the rotor in sealing engagement between the side plates 11 and 12 by fluid pressure led from the discharge chamber 55 to act against side plate 12 to force it to the left, as seen in FIG. 1, against the right-hand side of rotor 16, as seen in the same figure.

As shown in FIGS. 1 and 4, the side plate 12 is received within a counterbored end wall of front head 14 and is sealed at its outer periphery by seal 58 on the chamfered edge of side plate 12 and by an annular seal ring 60 to form an annular pressure chamber 61 which, as seen in FIG. 4, is placed in communication via duct 62 in side plate 12, channel 63 in stator 10 and duct 64 in side plate 11 with the discharge chamber 55. An 0- ring seal 65, positioned in a counterbored portion of channel 63, is compressed between the stator 10 and side plate 12 to prevent flowback of fluid under pressure into the adjacent working chambers. During operation of the compressor, as fluid pressure is built up in discharge chamber 55 this fluid pressure will be transmitted through the above described passages to force the side plate 12 into sealing engagement with the side surface of rotor 16. The diameter of the seal 60 is chosen to provide suflicient surface area between it and the outer periphery of the side plate 12 to obtain the desired sealing force of the side plate against the rotor 16. Any axial displacement of the shaft 27 is compensated for by the thrust washer 30, previously described, and the thrust washer arrangement 66 encircling shaft 27 adjacent to the right-hand eccentric portion 26, as seen in FIG. 1, and the front head 14.

It can be seen from the arrangement of the parts described and by the preferred arrangement for connecting the rear and front heads to the stator 10, by the band clamps 15, that there is provided a low cost lightweight compressor that is readily serviceable and adaptable for use in an automobile air conditioning system.

What is claimed is:

1. A compressor comprising a stator having an inner peripheral wall with N+1 lobes disposed about an axis, first casing means and second casing means on the axial sides of said stator, an epitrochoidal rotor with N lobes, a shaft rotatably mounted in said casing means along said stator axis, eccentric means carried by said shaft for supporting said rotor for rotation within said stator to form therewith variable volume working chambers, a first side plate and a second side plate positioned on opposite sides of said rotor for sealing engagement with the lateral faces of said rotor, means for pressure loading said second side plate against said rotor, and means in said first casing means and said first side plate for the controlled ingress and egress of fluid into and out of said working chambers and means in said second casing means and said second side plate for the controlled ingress of fluid into said working chambers, said lobes of said rotor having fluid channels therein for communication with the means in said first side plate and said second side plate for the ingress of fluid into said working chamber.

2. A compressor according to claim 1 including gear means comprising an internal gear on said rotor and an external gear on said first side plate to effect, together with said eccentric means on said shaft, planetary rotation of said rotor within said stator.

3. A compressor including a housing having a stator having N +1 lobed inner contours, a rotor having N hollow lobes journaled for planetary rotation in said stator to form therewith variable volume working chambers, a first head and a second head disposed on opposite sides of said stator, a first side plate disposed between said first head and said stator, said first head and said first side plate having inlet and discharge passages therein for providing communication to and from said working chambers, a second side plate disposed between said second head and said stator and axially moveable with respect to said rotor, said second head and said second side plate having inlet passages therein for providing communication to said working chambers and interconnected to said inlet passages in said first side plate by said hollow lobes of said rotor, seal means positioned between said second head and said second side plate to form therewith a pressure chamber, passage means connecting said pressure chamber to said discharge chamber whereby said second side plate is pressure loaded into sealing engagement with said'1o tor.

4. A compressor according to claim 3 including a drive shaft journaled in said housing and having eccentric means thereon, said rotor being drivingly connected to said eccentric means, and gear means comprising an internal gear on said rotor and an external gear fixed relative to said stator to effect planetary rotation of said rotor.

5. A compressor according to claim 3 wherein the width of said rotor is greater than the width of said stator so that the side surfaces of said rotor are in sealing engagement with said first side plate and said second side plate.

6. A compressor comprising a housing having opposed end casings with a stator therebetween, one of said end casings having an annular inlet chamber connected to an inlet, and an annular discharge chamber connected to a discharge outlet, said other end casing having an annular inlet chamber, said stator having an inwardly facing peripheral wall With N-I-l number of lobed inner contours, side plates positioned in said housing on opposite sides of said stator and secured against relative rotational movement with respect to said stator, with at least one of said side plates being moveable axially with respect to said stator and connected to said discharge chamber, a drive shaft journaled in said housing for rotary motion and having eccentric means thereon, a rotor having N num- 6 ber of lobes drivingly connected to said eccentric means on said shaft, each of said lobes having a fluid channel therethrough and each of said lobes having side wall surface portions engaging said side plates, internal gear means associated with said rotor and external gear means fixed with respect to said stator, said internal gear means cooperating with said external gear means to eifect planetary rotation of said rotor as it is driven by said eccentric means on said drive shaft, said rotor, said stator and said side walls forming variable volume working chambers, inlet passage mean in each of said side plates in communication with said annular inlet chambers in said'side walls and adapted to be sequentially in communication with said working chambers as controlled by said wall surface portions of said lobes of said rotor, and valved discharge ports in one of said side plates in communication with said working chambers and with said annular discharge chamber.

References Cited UNITED STATES PATENTS 3,221,664 12/1965 Jernaes 41861 3,289,601 12/1966 Compton 418-61 3,547,565 12/1970 Eddy 418-61 3,390,667 7/1968 Beurtheret 418-61 3,240,158 3 1966 Brundage 418- 133 3,512,905 5/ 1970 Waldorif 418-61 CORNELIUS I. HUSAR, Primary Examiner J. I. VRABLIK, Assistant Examiner US. 01. X.R. 418-131, 183

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