Rotary Positive Displacement Device

Technical Field

A trochoidal rotary chamber device which can be used for compression and expansion of fluid, pumping of liquid, or as a hydraulic motor.

Background Art

Trochoidal rotary expansible chamber devices are well known to those skilled in the art. Thus, as is disclosed in United States patent 4,395,206 of Hoffman, these devices generally comprise a housing defining a cavity in which is mounted a rotor rotatable in a planetating fashion.

In the prior art rotary expansible chamber devices, the working chambers are generally sealed with radially extending apex seals positioned along intersection lines between adjoining peripheral faces on the envelope curve surface. A substantial problem with these rotary engine devices was discovered shortly after their introduction. Thus, as early as 1965, in, e.g.. United States patent 3,213,801 of Venygr, it was disclosed that "Efficient opera¬ tion of the afore-described apparatus is predicated on good sealing connections between the sealing members and the inner casing wall, and between the sealing members and the rotor. The sealing members move circumferentially relative to the casing wall during operation of the engine, and they move relative to the rotor in a direction which has a pre¬ dominant radial component as the several compartments are increased and decreased in radial size during relative movement of rotor and stator."

Venygr also disclosed that "It is difficult to main¬ tain the necessary tight sealing engagement under the condi¬ tions of high temperature and high pressure differentials under which the sealing members frequently operate....Seiz¬ ing and wear reduce the useful life of conventional sealing members, and vibration of the members at resonant frequen¬ cies causes grooving of the internal casing walls. When the walls have to be made of case hardened steel or other mate¬ rial resistant to grooving, mass production of the engines becomes difficult."

The problems disclosed by Venygr in his 1965 patent, to the best of applicants' knowledge., have not yet been solved by any prior art device. Consequently, the Wankel engine/compressor, which once held such substantial commer¬ cial promise, now has only very limited commercial use.

It is another object of this invention to provide a rotary mechanism in which the incidence of seizing, wear, and grooving is substantially reduced.

It is yet another object of this invention to provide a rotary mechanism which is substantially more durable, and reliable than prior art rotary mechanisms.

It is yet another object of this invention to provide a rotary mechanism in which the incidence of vibration, impact, and chatter within the device is minimized.

Summary of the invention

In accordance with this invention, there is provided a rotary device comprised of a housing, a shaft disposed within said housing, a rotor mounted on said shaft, and a multiplicity of solid cylindrical rollers disposed on the inner surface of said housing and said rotor and rotatably mounted within an external surface of said rotor.

Brief description of the drawings

The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements, and wherein:

Figure 1 is a perspective view of one preferred rotary mechanism of this invention;

Figure 2 is an axial, cross-sectional view of the mechanism of Figure 1;

Figure 3 is a perspective view of the eccentric crank of the mechanism of Figure 1;

Figure 4 is an axial, cross-sectional view of the eccentric crank of Figure 3;

Figure 4A is a transverse cross-sectional view of the eccentric crank of Figure 3;

Figure 5 is a perspective view of the rotor of the device of Figure 1;

Figure 6 is an axial, cross-sectional view of the rotor of Figure 5;

Figure 7 is a transverse, cross-sectional view of the rotor of Figure 5;

Figure 8 is an exploded, perspective view of the device of Figure 1;

Figure 9 is a perspective view of one of the rollers of the device of Figure 1;

Figure 10 is an axial, cross-sectional view of the roller of Figure 9;

Figure 11 is transverse, cross-sectional view of the roller of Figure 9;

Figures 12 through 17 are are each axial sectional views of the device of Figure 1, showing the rotor disposed within the housing of such device at various times during a

partial cycle cycle;

Figure 18 is a perspective view of another preferred embodiment of a roller which may be used in the device of Figure 1;

Figure 19 is a sectional view of the end of the roller of Figure 18;

Figure 20 is a sectional view of the end of another roller which may be used in the device of Figure 1;

Figure 21 is a perspective view of another preferred embodiment of a roller which may be used in the device of Figure 1;

Figure 22 is a sectional view of the end of the roller of Figure 21;

Figure 23 is a sectional view of the end of another roller which may be used in the device of Figure 1;

Figure 24 is a cross-sectional of a guided rotor mechanism close-coupled in a hermetic fashion to an electric motor;

Figure 25 is a cross-sectional view of a guided rotor mechanism close-coupled to a combustion engine of a recipro¬ cating or guided rotor type;

Figure 26 is a cross-sectional view of a stacked rotor assembly;

Figure 27 is a cross-sectional view of a guided rotor pump and/or motor;

Figure 28 is a cross-sectional view of a guided rotor mechanism arranged as a compression/expansion device;

Figure 29 is a schematic of a means for generating an epictroichoidal curve;

Figure 30 is a partial sectional view of one preferred rotor used in the apparatus of this invention;

Figure 31 is a partial sectional view of another

preferred rotor used in the apparatus of the invention;

Figure 32 is a partial sectional view of the rotor of Figure 30, illustrating the recesses on the sides thereof;

Figure 33 is another partial sectional view of the rotor of Figure 30;

Figure 34 is is a sectional view of the shaft used in the apparatus of Figure 1; and

Figure 35 is a perspective view of a triangular rotor which can be used in the apparatus of the invention.

Description of the preferred embodiments

Rotary piston mechanisms of various types are well known and are disclosed, e.g., in United States patents 2,873,250 of Batten, 2,988,065 of Wankel et al. , 2,866,417 of Nubling, 3,323,498 of Kraic et al, 3,671,154 of Kolbe et al., 3,797,974 of Huf, 3,923,430 of Huf, and the like.

Figure 1 is a perspective view of one preferred rotary mechanism 10. Referring to Figure 1, it will be seen that rotary mechanism 10 is comprised of housing 12, shaft 14, rotor 16, and solid rollers 18, 20, 22, and 24.

Referring again to Figure 1, it will be seen that housing 12 is preferably an integral structure. However, as will be apparent to those skilled in the art, housing 12 may comprise two or more segments joined together by convention¬ al means such as, e.g., bolts.

In one embodiment, housing 12 consists essentially of steel. As is known to those skilled in the art, steel is an alloy of iron and from about 0.02 to about 1.5 weight per¬ cent of carbon; it is made from molten pig iron by oxidiz¬ ing out the excess carbon and other impurities. See, e.g., pages 23-14 to 23-56 (and especially page 23-54) of Robert H. Perry et al. 's "Chemical Engineers' Handbook," Fifth

Edition (McGraw-Hill Book Company, New York, 1973). In this embodiment, it is especially preferred to use low carbon steel.

In another embodiment, housing 12 consists essentially of aluminum. In yet another embodiment, housing 12 consists essentially of bronze. In yet another embodiment, housing 12 consists essentially of plastic. These and other suit¬ able materials are described in George S. Brady et al.'s "Materials Handbook," Thirteenth Edition (McGraw-Hill, Inc., New York, 1991) .

One advantage of applicants' rotary mechanism 10 is that the housing need not be constructed of expensive alloys which are resistant to wear; and the inner surface of the housing need not be treated with one or more special coat¬ ings to minimize such wear. Thus, applicants' device is substantially less expensive to produce than prior art devices.

Housing 12 may be produced from steel stock (such as, e.g., C1040 steel stock) by conventional milling techniques. Thus, by way of illustration and not limitation, one may use a computer numerical controlled milling machine which is adapted to cut a housing 12 with the desired curved surface.

Referring again to Figure 1, it will be seen that housing 12 is comprised of an inner surface 26.

Figure 2 is a view of inner surface 26. Referring to Figure 2, and in the preferred embodiment illustrated there¬ in, it will be seen that surface 26 defines a multiplicity of lobes 28, 30, and 32 which, in combination, define an inner surface 26 which has a continuously changing curva¬ ture.

Referring again to Figure 2, it will be seen that, with regard to lobe 28, the distance from the centerpoint 34

to any one point on lobe 28 will preferably differ from the distance from the centerpoint 34 to an adjacent point on lobe 28; both the curvature and the distance from the centerpoint 34 is preferably continuously varying in this lobe (and the other lobes). Thus, for example, the distance 36 between point 34 and 38 is preferably substantially less than the distance 40 between points 34 and 42; as one progresses from point 38 to point 42 around surface 26, such distance preferably continuously increases as the curvature of lobe 28 continuously changes. Thereafter, as one pro¬ gresses from point 42 to point 44, the distance 46 between point 34 and point 44 preferably continually decreases.

Referring again to Figure 2, it will be apparent to those skilled in the art that, in this preferred embodiment, the same situation also applies with lobes 30 and 32. Each of such lobes is preferably defined by a continuously chang¬ ing curved surface; and the distance from the centerpoint 34 is preferably continuously changing between adjacent points.

In the preferred embodiment illustrated in Figure 2, it is preferred to have at least two of such lobes. It is more preferred to have at least three of such lobes. In another embodiment, at least four of such lobes are present.

It is preferred that each lobe present in the inner ^' surface 26 have substantially the same curvature and shape as each of the other lobes present in inner surface 26. Thus, referring to Figure 2, lobes 28, 30, and 32 are dis¬ placed equidistantly around centerpoint 34 and have substan¬ tially the same curvature as each other.

The curved surface 26 may be generated by conventional machining procedures. Thus, as is disclosed in U.S. patent 4,395,206, the designations "epitrochoid" and "hypo-

trochoid" surfaces refer to the manner in which a trochoid machine's profile curves are generated; see, e.g., United States patent 3,117,561.

An epitrochoidal curve is formed by first selecting a base circle and a generating circle having a diameter great¬ er than that of the base circle. The base circle is placed within the generating circle so that the generating circle is able to roll along the circumference of the base circle. The epitrochoidal curve is defined by the locus f points traced by the tip of radially extending generating or draw¬ ing arm, fixed to the generating circle having its inner end pinned to the generating circle center, as the generating circle is rolled about the circumference of the base circle (which is fixed) .

In one embodiment, the epitrochoidal curve is generat¬ ed in accordance with the manner illustrated in Figure 29. Referring to Figure 29, it will be seen that base circle 110 with radius 112 extending from centerpoint 114 is main¬ tained in a fixed position.

Referring again to Figure 29, a smaller circle 116 with a radius 118 is caused to roll over the perimeter 120 of circle 110. Radius 118 is chosen so that the ratio between radius 112 and radius 118 is equal to an exact integer; thus, when the smaller circle 116 completes one ^' journey around the base circle 110, it will have undergone an integral number of turns.

As smaller circle 116 is rolling aroung the perimeter 120 of base circle 112, any point chosen on the radius 118 of the smaller circle 116 (such as, for example, point 122) will, during the travel of such point, define an epitrochoi¬ dal curve.

The distance between the centerpoint 124 of smaller

circle 116 and point 122 is the eccentricity 58 (see Figure 4). Consequently, the point 122 should be chosen so that the desired eccentricity 58 is present.

As is disclosed on lines 36 to 55 of column 5 of United States patent 4,395,206, it is common practice to recess or carve out the corresponding peripheral profile of the epitrochoid member a distance "x" equal to the outward offset of the apex seal radius (see Figure 4 of such patent). As stated on lines 48 et seq., in "...the case of an inner envelope type device 20', as shown in FIG. 4, such carving out requires that the actual peripheral wall surface profile 33 which defines the cavity 34 of the housing 35 be everywhere radially outwardly recessed from the ideal epi¬ trochoid profile 36. In the case of an outer envelope device 21', as illustrated in FIG. 5, such carving out requires that the actual peripheral face profile of the epitrochoid working member, rotor 38, be everywhere inwardly radially recessed from the ideal epitrochoid profile 39."

Referring again to Figure 2, it will be seen that applicants' inner housing surface profile 26 is generated from ideal epitrochoidal curve 48 and is outwardly recessed from ideal curve 48 by a uniform distance 50. In one pre¬ ferred embodiment, uniform distance 50 is a function of the eccenticity of the eccentric 58 used in device 10 (see Figure 4) .

Referring again to Figure 1, it will be seen that rotary mechanism 10 is comprised of shaft 14 on which eccen¬ tric 52 is mounted. This assembly is also shown in Figures 3, 4, and 4a.

Referring to Figure 3, it will be seen that shaft 14 preferably has circular cross-section and is cylindrical in shape. Shaft 14 is connected to eccentric 52. In one

embodiment illustrated in Figure 3, shaft 14 and eccentric 52 are integrally formed and connected.

In one preferred embodiment, both shaft 14 and eccen¬ tric 52 consist essentially of steel such as, e.g., carbon steel contains from about 0.4 to about 0.6 weight percent of carbon.

Figure 4 is a front view of the shaft/eccentric assem¬ bly of Figure 3. Referring to Figure 4, it will be seen that shaft 14 has a geometric center 54, and eccentric 52 has a geometric center 56. The distance 58 between center 54 and center 56 is the eccentricity of the structure. As is known to those skilled in the art, eccentricity is the distance of the geometeric center of a revolving body (eccentric 52) from the axis of rotation (center 54 of shaft 14).

Referring again to Figure 2, and in the preferred embodiment illustrated therein, it is preferred that the distance 50 be from about 0.5 to about 5.0 times as great as the eccentricity 58 (see Figure 4). In a more preferred embodiment, the distance 50 is from about 1.0 to about 2.0 as great as eccentricity 58. In one embodiment, distance 50 is about 0 times as great as eccentricity 58.

Referring again to Figure 2, in this preferred embodi¬ ment, the distance 50 is equal to the radius of solid roller 24. As will be apparent to those skilled in the art, and referring to Figure 1, each of solid rollers 18, 20, 22, and 24 will preferably have a radius equal to distance 50.

Referring again to Figure 1, rotor 16 is mounted on eccentric 52, which in turn is mounted on shaft 14. Shaft 14 is supported by an external means (not shown), such as an end housing (not shown) with a bearing system. Thus, be¬ cause shaft 14 is supported by an external means, the rotor

16/roller 18 assembly need not be supported by the inner surface 26 of housing 12 during most of the rotation cycle.

Referring to Figure 1, it will be seen that, when rotor 16 is in the position depicted, roller 22 is not necessarily contacting lobe 30, roller 20 is contacting lobe 28, and roller 24 is contacting lobe 32. As will be appar¬ ent to those skilled in the art, this situation changes when the rotor 16 rotates in the direction of arrow 60 and will be affected by, e.g., factors such as gravity, the distance between shaft 14 and the inner surface 26 at any point of rotation, and the like.

One preferred embodiment of rotor 16 is illustrated in Figures 5, 6, and 7, in which a four-sided rotor is il¬ lustrated. Referring to Figure 5, it will be seen that rotor 16 is preferably an integral structure which is comprised of an bore 62 centrally disposed within the body of rotor 16. Bore 62 is adapted to eccentric 52 (not shown in Figure 5). In one embodiment, a bearing is preferably disposed between eccentric 52 and bore 62 (see Figure 8, and refer to bearing 64) .

Referring again to Figure 5, it will be seen that rotor 16 has a number of sides equal to the number of lobes within housing 12 plus one; and the sides of the rotor 16 are disposed equally. Thus, for example, when housing 12 contains two such lobes, rotor 16 will be substantially in the shape of an equilateral triangle. When housing 12 contains three such lobes, rotor 16 will be substantially in the shape of a square. When housing 12 contains four such lobes, rotor 16 will be substantially in the shape of penta¬ gon.

At the intersection of each of the sides of rotor 16, a partial bore is provided to receive a roller (not shown)

and to capture it in the radial direction; see, for example, partial bores 61, 63, 65, and 67. The rollers (not shown) may be loosely disposed within such partial bores (see Figure 1) and are removable in the axial direction.

Referring again to Figure 2, the bore in which roller 24 is disposed is not shown for the sake of simplicity and illustration. However, it will be apparent to those skilled in the art, that the center of the partial bore in which roller 24 is disposed, as such center rotates around points 54 and 56 (as is shown in Figure 4), will move along the ideal epitrochoidal curve.

Referring again to Figure 5, recesses 64, 66, 68, and 70 are provided in side 72 of rotor 16; and these recesses are adapted to communicate with ports (not shown) through which gas or fluid may be introduced and exhausted. In one embodiment (not shown), such ports exist on both sides of the housing 12; and, in such case, it is preferred to have similar recesses on both sides of rotor 16. In another embodiment, not shown, such ports exist on one side of housing 12 and such recesses exist on one side or on both sides of rotor 16.

In the embodiment illustrated in Figure 5, each of recesses 64, 66, 68, and 70 is formed between and communi¬ cates between the front face 72 of rotor 16 and one of sides 300 of such rotor. Although such detail has been omitted for the sake of simplicity in Figure 5, similar recesses are preferably formed between and communicate with the back face 72 74 of rotor 16 and one of sides 300. As will be dis¬ cussed later in this specification, each of such recesses are preferably disposed symmetrically and equidistantly between the ends of sides 300.

In one preferred embodiment, illustrated in the Fig-

ures, each of such recesses has a substantially U-shaped cross-sectional shape defined by a first linear side, a second linear side, and an arcuate section joining said first linear side and said second linear side. In this embodiment the first linear side and the second linear side are disposed with respect to each other at an angle of less than ninety degrees, and the substantially U-shaped cross sectional shape has a depth which is at least equal to its width.

In one embodiment, not shown, one or more of recesses 64, 66, 68, and 70 extend from side 72 of rotor 16 to the opposite side 74 of rotor 16.

Figure 8 is an exploded perspective view of the rotary device 10 of Figure 1. Referring to Figure 8, it will be seen that the rotary device 10 is preferably comprised of a back wall 75 and a corresponding front wall (not shown in Figure 8). In the preferred embodiment illustrated in this Figure, it will be seen that back wall 75 (and the corre¬ sponding front wall) is comprised of a bore 76 which is adapted to receive end 78 of shaft 14. It will also be seen that back wall 75, in this embodiment, is comprised of ports 80, 82, 84, 86, and 88 through which liquid and/or gas may be introduced to or expelled from. As will be apparent by reference to Figures 12 through 17, such gas and/or liquid is preferably introduced to one side of rotor 16, between a lobe of housing 12 and a side of rotor 16.

Referring again to Figure 8, it will be seen that solid rollers 18, 20, 22, and 24 are disposed in partial bores 63, 61, 67, and 65, respectively. A preferred embodi¬ ment of these rollers is illustrated in Figures 9, 10, and 11.

Referring to Figures 9, 10, and 11, it will be seen

that roller 18 is preferably a solid cylindrical structure. Each of the rollers 18, 20, 22, and 24 have a radius 90 which is substantially equal to the radius of each of the other of such rollers and, preferably, is also equal to distance 50 (see Figure 2).

Referring again to Figure 9, 10, and 11, solid rollers 18 et seq. may comprise or consist essentially of any suit¬ able material which will be dimensionally stable at the working temperature, have good impact resistance, have good wear resistance, and be substantially dimensionally stable in the working environment. By way of illustration and not limitation, one may use a metal material, a ceramic materi¬ al, a plastic material, a reinforced plastic matrerial, and a composite material.

In one preferred embodiment, the material making up rollers 18 differs from the material making up the bearing surfaces of the partial recesses of rotor 16. In particu¬ lar, the material making up the bearing surface 59 of par¬ tial recesses 61 et seq. (see Figure 5) preferably differs from the material making up the solid roller 18.

In one preferred embodiment, solid rollers 18 et seq. each consist essentially of bronze, and rotor 16 consists essentially of aluminum. In another embodiment, the solid rollers are made out of bronze, and the rotor is made out ^' of steel.

In one embodiment, each of the rollers 18, 20, 22, and 24 consists essentially of a fiber-reinforced non-metal¬ lic material. In one aspect of this embodiment, the fiber used is an aramid. As is known to those skilled in the art, "aramid" is the generic name for a class of highly aromatic polyamide fibers derived from p-phenylenediamine and ter- ephthaloyl chloride. In this aspect, short lengths of such

aramid fiber are preferably randomly disposed within a matrix of an epoxy resin. This fiber reinforced material is commercially available and may be obtained under the trade- name "HYD AR."

The rollers 18, 20, 22, and 24 are disposed within partial bores 61, 63, 65, and 67 and should be free to rotate therein. Thus, each of such partial bores may be so configured that there is clearance between the roller and the bore and thus the roller is free to rotate. As will be apparent to those skilled in the art, the configurations of such partial bores will preferably be designed so that, even under the conditions of use, which might involve elevated temperature, there will be a sufficient clearance between the rollers and the bores to allow freedom of rotation.

Referring again to Figure 8, it will be seen that rotor 16 is shown with a substantially rectilinear shape and partial bores provided at the apices of such shape. In the preferred embodiment illustrated in Figure 8, the sides of rotor 16 are slightly beveled near each of partial bores 61, 63, 65, and 67 to minimize the opportunity for such sides to contact any portion of the inner surface 26 of housing 12.

Figure 12 is a partial sectional view of the rotor assembly 10 of Figure 1, illustrating the relative positons of rotor 16 and housing 12 at zero degrees of operation. ' In this position, it will be seen that, when roller 20 is at "zero point" 92, port 84 communicates with recess 66, but port 80 does not communicate with any such recess. Thus, in this position, gas and/or fluid may be introduced from port 84, into recess 66, and then flow into space 94 which exists between wall 96 of rotor 16 and inner wall 26 of housing 12. The gas or fluid so introduced into volume 94 will be com¬ pressed once port 84 ceases communicating with recess 66 and

as shaft 14 continues to rotate in the direction of arrow 60.

As the shaft 14 continues to rotate in the direction of arrow 60, it will bring the rotor 16 to the position depicted in Figure 13.

Referring to Figure 13, it will now be seen that roller 20 has advanced to point 98 due to an approximately 60 degree rotation of shaft 14. It will be seen that, in this position, port 84 still communicates with recess 66. However, it should also be noted that the volume 94 between wall 96 and lobe surface 28 is greater than the comparable volume 94 of the position depicted in Figure 12. Thus, this larger volume 94 allow the introduction of more gas or fluid through port 84.

Referring to Figure 14, it will now be seen that roller 20 has advanced to point 100 due to the rotation of shaft 14 an additional 60 degrees in the direction of arrow 60. It will seen that, in this embodiment, the port 84 is no longer communicating with recess 66 but that, in part, it is communicating with space 94. In this position, the volume 94 is yet even larger than the volume 94 of the position of Figure 13; and, thus, more fluid and/or gas may be introduced into the space 94. It will noted that, in the positions depicted in Figures 12, 13, and 14, volume 94 communicates only with port 84.

Referring to Figure 15, which is the position obtained when shaft 14 rotates yet another 60 degrees, it will be seen that, in this position, port 84 no longer communicates with volume 94. In this position, there is no port in communication with the space 94. However, it also should be noted that the volume of space 94 in this position is great¬ er than the comparable volumes of space 94 in the positions

depicted in Figures 12, 13, and 14.

Figure 16 is the position obtained when shaft 14 rotates another 60 degrees. In this position, neither port 82 nor port 84 is communicating with space 94. However, the volume of space 94 is smaller than the volume of the compar¬ able space 94 of the position of Figure 15; and, thus, the gas within such space is being compressed.

Figure 17 is the position obtained when shaft 14 rotates yet another 60 degrees. It will be seen that, in this position, neither port 82 nor port 84 communicates with space 94. Furthermore, the volume of space 94 is still further reduced, thereby further compressing the gas and/or fluid within such space.

Figure 18 is a perspective view of a roller 130 which may be used in rotor 16. Referring to Figure 18, it will be seen that roller 130 is comprised of concentric grooves 132 at either proximal end 134 and/or distal end 136 (grooves not shown). As will be apparent to those skilled in the art, these concentric, circular grooves 132 improve the sealing between the rotor 16 and the sidewalls of the hous¬ ing.

Figure 19 is a sectional view of the end 134 of the roller 130, illustrating one configuration of the grooves 132. Figure 20 illustrates another possible configuration for grooves 132.

Figure 21 is a perspective view of another roller 140 which, in this embodiment, is comprised of phonographic (spiral) grooves 142. As will be apparent to those skilled in the art, such spiral grooves 142 may exist at proximal end 144 and/or distal end 146 (grooves not shown).

Figure 22 is a sectional view of end 44 illustrating one configuration of spiral grooves 142. Figure 23 is

illustrates another possible configuration for either end 144 and/or 146, in which a center relief portion 148 is machined into the end of the roller.

Figure 24 is a sectional view of a hermetic compres¬ sor/electric motor system 150 which is comprised of housing 12 and end plate 152 in which ports 80, 82, 84, and 86 are located. The assembly 150 is comprised of a driving member which itself comprises a rotor 154, a stator assembly 156, a shaft 158, bearings 160, and a housing 162 which, in one preferred embodiment, is a hermetic enclosure with a com¬ pressor.

Figure 25 is a sectional view of a compressor/internal combustion engine system 170. The combustion engine system may comprise a reciprocating engine and/or a Wankel rotary engine; alternatively, it may comprise the guided rotor mechanism utilized as a combustion engine. Referring to Figure 25, it will be seen that the preferred device il¬ lustrated in this Figure is comprised of a housing 172 adapted for use as a combustion engine, end plates 174 comprised of fluid cooling means 176, a shaft 178,. ignition means 180. The center housing 182 separates the pair of rotors illustrated. As will be apparent to those skilled in the art, the device of this Figure may comprise one rotor, two rotors, three rotors, four rotors, etc. The device also is comprised of end plate 188.

Figure 26 is a sectional view of a stacked rotor assembly 190 which is comprised of two substantially similar rotors 16 and 192 and end plate 200. In this embodiment, rotors 16 and 192 are substantially identical, and are housed within body 196. It will be apparent to those skilled in the art, however, that one may use rotors and/or housings with different geometries, and/or dimensions,

and/or portings, and/or materials, and/or other features to achieve a variety of different effects. It will be apparent that more than two rotors may be stacked on the same shaft 198.

In one embodiment, not shown, a series of four rotors are used to compress natural gas. The first two stacked rotors are substantially identical and relatively large; they are 180 degrees out of phase with each other; and they are used to compress natural gas to an intermediate pressure level of from about 150 to about 200 p.s.i.g. The third stacked rotor, which comprises the second stage of the device, is substantially smaller than the first two and com¬ presses the natural gas to a higher pressure of from about 800 to about 1,000 p.s.i.g. The last stacked, which is yet smaller, is the third stage of the device and compresses the natural gas to a pressure of from about 3,600 to about 4,500 p.s.i.g.

It will be apparent to those skilled in the art that, instead of stacking the first two rotors of the first stage, one could construct one rotor adapted to effect the same pressure increase. However, by using two identical stacked rotors, the centrifugal forces of the rotors can be counter¬ balanced, and improved fluid flow can be achieved.

Figure 27 is a sectional view of hydraulic pump/motor assembly 202 in which the inlet ports 204 and outlet ports 206 are configured and disposed so that ports 204 and 206 are never simultaneously in communication with the operating volume of the fluid. Furthermore, at least one of such ports 204 and 206 is always in communication with the work¬ ing volume throughout the period during which the working volume is changing. In the embodiment illustrated, a three- lobe pump is depicted which will contain three pairs of such

ports .

Figure 28 is a sectional view of a close coupled compressor/expander system 210 which contains a guided rotor compressor 10 which, in the preferred embodiment illustrat¬ ed, is integrally connected to a guided rotor expansion device 212 comprised of expansion housing 214, rotor 216, shaft 218, intermediate housing 220, end housing 222, and three pairs of inlet ports 224 and discharge ports 226 (only one of which pairs is illustrated in the Figure). The expansion assembly 212 may utilize the high-pressure working fluid originally compressed by compressor assembly 10. Alternatively, or additionally, it may utilize a different high-pressure process stream.

In one embodiment, not shown, the compressor is com¬ prised of two or more stacked and/or staged rotors. In another embodiment, not shown, the expansion device is com¬ prised of two or more stacked and/or staged rotors.

Figure 30 is a partial sectional view of a preferred embodiment of rotor 16 from which irrelevant detail has been omitted for the sake of clarity. Referring to Figure 30 ,it will be seen that rotor 16 is comprised of a multiplicity of sides such as, e.g., side 300. The rotor depicted in Figure 1 will have four such identical sides 300 corresponding to three lobes of housing 12. By comparison, when housing 12 has two lobes, the rotor 16 will have three such identical sides 300.

Referring to Figure 1, for any given rotor 16, each of the sides 300 will have preferably the same dimen¬ sions and geometry. In Figures 30 and 31, only one of such sides 300 is shown, it being understood that the other sides of rotor 16 not shown are substantially identical.

Referring again to Figure 30, it will be seen that

side 300 has a discontinous shape, i.e., it is not formed of either only one linear side or only one continuous arcuate section with a constant radius. Thus, referring to Figure 30, it will be seen that side 30 has a shape which is formed from at least two sections having different shapes.

If one section of a side is linear, and a second section of a side is arcuate, then the two sections have different shapes. If one section of a side is arcuate, and a second section of a side is also arcuate, the two arcuate sections will have different shapes when they have different radii of curvature. If one section of a side is linear, and a second section of the side also is linear, they will have different shapes if a first centerline constructed perpen¬ dicular to the first linear section is not parallel to a second centerline constructed perpendicular to the second linear section.

Referring to Figure 30, and in the preferred embodi¬ ment illustrated therein, it will be seen that side 300 has a composite shape formed of linear sections 302, 304, and 306. Section 302 is formed between points 308 and 310; section 304 is formed between points 310 and 312; and section 306 is formed between points 312 and 314.

Although the preferred embodiment of Figure 30 depicts a shape comprised of three separate linear poritons 302, 304, and 306, it will be understood that a shape comprised of two separate linear portions also may be used in rotor 16. Such a shape is depicted in Figure 30A, in which linear sections 297 and 299 are illustrated.

Referring again to Figure 30, it will be seen that centerlines 316, 318, and 320 may be constructed for sec¬ tions 302, 304, and 306, respectively, by conventional geometrical means. As is readily known, these centerlines

so constructed are normal to the plane of each respetive linear surface. Because none of these centerlines are parallel to each other, the linear sections 302, 304, and 306 each have different shapes.

The centerline of section 302, centerline 316, is neither coincident with nor parallel to either the center¬ line of section 304 (centerline 318) of the cneterline of section 306 (centerline 320); and the same may be said for each of the centerlines of sections 304 and 306.

Figure 31 is a partial sectional view of another preferred rotor 16, which uses a shape somewhat different than that depicted for side 300.

Referring to Figure 31, it will be seen that side 301 is a composite shape comprising at least two separate ar¬ cuate sections 303, 305, and 303. Section 303 is formed between points 309 and 311; section 305 is formed between points 311 and 313; and section 307 is formed between points 313 and 315. Inasmuch as the radius of curvature for each of arcuate sections 303 and 307 differs from the radius of curvature for section 305, each of sections 303 and 307 has a shape which differs from that of section 305.

Although the preferred embodiment of Figure 31 depicts a shape comprised of three separate arcuate portions 303, 305, and 307, it will be understood that a shape comprised of two separate arcuate portions also may be used in rotor 16. It will also be apparent to those skilled in the art that a combination of arcuate and linear portions also may be used.

In the embodiment depicted in Figure 31, the radius of section 303 is substantially equal to the radius of section 307 but differs from (is smaller than) the radius of sec¬ tion 305.

Referring again to Figure 31, it will be seen that centerlines 317, 319, and 321 may be constructed for sec¬ tions 303, 305, and 307, respectively, by conventional geometrical means. As is readily known, these centerlines so construced are normal to the tangent at the midpoint of each respective arcuate surface.

Figure 32 is a sectional view of a preferred rotor 16 from which irrelevant detail has been omitted for the sake of clarity in order to illustrate and discuss the shape and location of the openings in sides 300, such as recess 64. Although four such recesses are utilized in one of appli¬ cant's preferred rotors (see Figure 5), it will be under¬ stood that the situation for each of the other recesses 66, 68, and 70 is identical to recess 64.

Referring to Figure 32, it will be seen that recess 64 extends from point 322 to point 324 and, thus, has a width 326. A centerline 318 may be constructed across width 326 by conventional means. The distance 330 between centerline 318 and end 308 of side 300 is equal to the distance 332 between centerline 318 and end 314 of side 300; and recess 64 is symmetrical around cetnerline 318. Thus, it will be apparent that recess 64 (and comparable recesses 66, 68, and 70) are both equidistant from the ends of side 300 and symmetrical about their midpoint.

Figure 33 is a partial sectional view of side 300 from which irrelevant detail has been omitted. Referring to Figure 33, it will be seen that width 326 of recess 64 is less than the diameter 91 of roller 18 (see Figure 10).

Figure 34 is a sectional view of shaft 52 (also see Figure 4). Referring to Figure 34, and in the preferred embodiment depicted therein, it will be seen that the eccentric 52 has a diameter 340 which is at least about 0.4

times as great as the height 0.4 times of rotor 16 (see Figure 6) .

In one preferred embodiment, the eccentricity 58 (see Figure 34) is from about 0.05 inches to about 10 inches.