US3884600A

US3884600A - Guidance means for a rotary engine or pump

Info

Publication number: US3884600A
Application number: US414000A
Authority: US
Inventors: Herbert Lewis Gray
Original assignee: Gray and Bensley Research Corp
Current assignee: Gray and Bensley Research Corp
Priority date: 1973-11-08
Filing date: 1973-11-08
Publication date: 1975-05-20
Anticipated expiration: 1992-05-20
Also published as: DE2450418A1; SE7414088L; IT1023096B; CA1016870A; JPS5821082B2; BR7408956D0; DD117510A5; JPS5074009A; ES431762A1; GB1486947A; IN142894B; FR2250892B3; CS193508B2; FR2250892A1; CH583847A5; GB1486946A; AU7438674A

Abstract

The invention provides a rotary engine or pump of the type comprising a body with an internal epitrochoidal cross-section chamber and a triangular cross-section rotor rotatable in the body chamber so as to form a plurality of working chambers that vary in volume upon relative rotation of the rotor and the body. A new guidance means for guiding the rotor in the required motion relative to the body comprise a first planar guide surface of essentially triangular shape movable with the rotor and a second planar guide surface movable with the body, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being of oval shape generated by the said first surface in their required relative motion. A seal for use between each rotor apex and the chamber wall comprises two co-operating seal members urged radially outwards by operating fluid of the mechanism.

Description

[4 1 May 20, 1975 GUIDANCE MEANS FOR A ROTARY ENGlNE OR PUMP Herbert Lewis Gray, Milton, Ontario, Canada [75] Inventor:

[73] Assignee: Gray & Bensley Research Corporation, Milton, Ontario, Canada 22 Filed: Nov. 8, 1973 [21] Appl. No.: 414,000

Primary ExaminerJohn J. Vrablik Attorney, Agent, or Firm-Stanley J. Rogers [57] ABSTRACT The invention provides a rotary engine or pump of the type comprising a body with an internal epitrochoidal cross-section chamber and a triangular cross-section rotor rotatable in the body chamber 50 as to form a plurality of working chambers that vary in volume upon relative rotation of the rotor and the body. A new guidance means for guiding the rotor in the required motion relative to the body comprise a first planar guide surface of essentially triangular shape movable with the rotor and a second planar guide surface movable with the body, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being of oval shape generated by the said first surface in their required relative motion. A seal for use between each rotor apex and the chamber wall comprises two co-operating seal members urged radially outwards by operating fluid of the mechanism.

6 Claims, 16 Drawing Figures PATENTEU HAY20 197s 8 84, 6 O 0 sum 10F 4 PATENTEU MAY 2 01975 SHEET 3 [)F 4 FIELD OF THE IN VENTION The present invention is concerned with improvements in rotary mechanisms of the type operable as an engine or as a pump or compressor.

REVIEW OF THEPRIOR ART Of the very large number of rotary engines that have been proposed hitherto only one has at this time achieved any substantial commercial success, namely that known as the Wankel rotary engine, as described, for example, in US. Pat. Ser, No: 2,988,065, issued June 13, 1961 to N.S.U. Motorenwerke AC. and Wankel G.m.b.H., and also in the book The Wankel Engine by Jan P. Norbye, published 1971 by Chelton Book Co., Library of Congress Cataloque Card No: 73-161624.

The most usual form of Wankel engine consists of one or more three-lobed hypotrochoidal cross-section rotors mounted for orbital motion within a two-lobed epitrochoidal cross-section chamber in the engine casing. The rotor rotates freely by means of an interposed bearing upon an eccentric portion of a main output shaft, this eccentric mounting being essential so that the rotor can exert the necessary torque on the mainshaft. Other lobe combinations can theoretically be used, but the one outlined appears to have been universally adopted.

Because of this eccentric mounting the rotor moves within the chamber in what is usually described as an orbital motion, which may be regarded as a combination of circular and pulsating motions of the rotor.

The rotation of the rotor on its bearing must be phased accurately with its motion in the chamber in order to provide a plurality of working chambers that vary in volume in the required manner upon relative rotation of the rotor and chamber. The current practice with the Wankel-type engine as described in the Wankel specification, the disclosure of which is incorporated herein by reference, is to provide the necessary phasing by means of an internal-toothed ring gear rigidly attached to the rotor meshing with a pinion reaction gear rigidly attached to the casing. With said universally adopted lobe configuration if the ring gear has 72 teeth then the reaction gear must have 48 teeth to produce a 3:2 ratio between them.

One of the problems encountered with the Wankel engine has been cooling of the rotor, and the solution often adopted has been to provide heat transferr to an external radiator by means of controlled pressure circulation of oil to and from the rotor. An arrangement for circulating cooling oil within the rotor interior is described and claimed in US. Pat. Ser. No: 3,102,683, issued Sept. 3, 1963 to N.S.U. Moterenwerke AG. and Wankel G.m.b.H. 1n the disclosed arrangement oil is fed to a chamber within the rotor interior where it performs its intended cooling function. The oil is distributed by centrifugal forces around the interior surface of this chamber in the form of a film thereof, and the oil is removed from the chamber while the thickness of this film is maintained at a constant value by the provision of a stationary disc which extends into the chamber. The shape of the disc periphery corresponds to the figure swept by the oil-receiving rotor internal chamber with provisions for maintaining the said oil film thickness, the disc having radially extending channels with openings that intercept the oil, so that it is forced through the openings into the channels and conveyed to another part of the engine (e.g., the casing and/or a cooler).

DEFINITION OF THE INVENTION It is an object of the invention to provide a new rotaty mechanism of the type comprising a three-lobed rotor of triangular crosssection operative within a two-lobed chamber of epitrochoidal cross-section.

It is a more specific object to provide a new rotaty mechanism of the type specified in the preceding paragraph, and comprising a new means for maintaining the rotor in correctly phased orbital motion within its chamber. It is a further object of the invention to provide a new rotary engine having an internal chamber of K value about 5.

In accordance with the present invention there is provided a rotary mechanism comprising a body, a shaft mounted by the body for rotation about a corresponding axis, the body providing an internal chamber having an internal peripheral surface of two-lobed epitrochoidal cross-section perpendicular to and symmetrical about the said shaft axis, a threelobed rotor of triangular cross-section mounted within the chamber for rotation about an axis displaced from and parallel to the said shaft axis, eccentric means connecting the shaft and the rotor for transmission of rotation between them, the rotor being symmetrical about its own axis and having a plurality of three circumferentiallyshaped apex portions in sealing engagement with the said chamber internal peripheral surface to form a plurality of three working chambers between the rotor external peripheral surface and the chamber surface that vary in volume upon relative rotation of the rotor and the chamber, and guidance means for guiding the rotor in the required motion relaive to the casing comprising a first essentially triangular guide surface movable with the rotor, symmetric about the rotor axis, and parallel to the rotor axis, and a second guide surface movable with the body, symmetric about the shaft axis, and parallel to the shaft axis, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being the oval shape generated by the said first surface in their required relative motion and having its major and minor axes parallel respectively to the minor and major axes of the internal body surface.

Preferably in a rotary engine the said internal chamber has a K value of 5.

DESCRIPTION OF THE DRAWINGS Particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:

FIG. 1 is an exploded view of one rotary mechanism operable as a motor or pump, the mechanism being shown exploded along the axis of rotation of the mainshaft thereof.

FIGS. 2 to 5 are schematic cross-section views on the line 2-2 of FIG. 1 to show the different positions that can be taken by the rotor relative to the chamber in which it is located, and the corresponding positions relative to the members constituting the guidance means,

FIG. 6 is a cross-section view on the line 6-6 of FIG.

2 and showing the mechanism in assembled condition,

FIG. 7 is a cross-sectional view through one of the rotor apices, perpendicular to the axis of rotation thereof, in order to show detail of the construction of the apex seals employed with the rotor,

FIGS. 8 and 9 are schematics of internal epitrochoidal paths in order to show certain limits in the geometry of the path that can be used, and

FIGS. 10 to 16 are graphs comparing the characteristics of known rotary engines with those that can be produced employing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As indicated above the rotary mechanism illustrated herein very schematically as a particular preferred embodiment may be employed as an engine or a compressor and, depending upon the particular application, will require certain additional equipment (such as a carburettor, oil-cooler, etc.) whose description is omitted since it is not essential for full ilustration and understanding of the present invention. The nature and characteristics of such additional equipment required will be apparent to those skilled in the art.

The mechanism consists of an outer casing indicated generally by the reference 10 and constituted by a pcripheral part 12 and two

end plates

14 and 16 fastened thereto by any suitable means, for example, by through-bolts 17. The casing provides an internal chamber 18 whose internal periphery 20 is symmetrical about a central longitudinal axis 22, the said periphery being of two-lobed epitrochoidal cross-section perpendicular to the axis 22. Bearings 24 in the end plates support a mainshaft 26 for rotation about an axis coincident with the axis 22. The shaft is provided with an eccentric portion 28 which is integral therewith or rigidly attached thereto, the eccentric portion being of circular cross-section perpendicular to a longitudinal axis 30, which is parallel to the axis 22 and spaced a distance r (FIG. 6) therefrom. This distance r is the effective eccentricity of the mechanism.

A three-lobed rotor indicated generally by the reference 32 is mounted by bearing part 34 for free rotation on the shaft eccentric portion 28, so that it can move in the so-called orbital or planetary motion within the chamber 18 as the shaft rotates. In this embodiment the rotor 32 has an external periphery constituted by three side walls 36 meeting at three corresponding apices 38, each apex being provided with a corresponding apex seal indicated generally by the reference 40. These seals are omitted from FIGS. 2 to 6 for simplicity of illustration. The external periphery of the rotor is of general equilateral triangle cross-section perpendicular to its axis and symmetrical about that axis, the sidewalls 36 being however slightly arcuate radially outwards and not straight. Working fluid can be introduced into the part of the chamber 18 not occupied by the rotor via an inlet 42 in the end plate 14 and removed via an outlet 43 in the member 12. The mechanism is also illustrated as comprising an ignition device 44 mounted in a corresponding opening 45, although other forms of device, or other ignition means (e.g., when the mechanism is a diesel engine) can be employed. Such a device is of course not required when the mechanism is a pump.

The structure so far described is also the basic structure of the Wankel rotary engine. As the rotor moves in its orbital motion a plurality of working chambers are formed between the

walls

20 and 36 that vary cyclically in volume. The operation of the device either as an engine or as a compressor is now so well known as not to require further description. In the Wankel engine however the rotor and main shaft are provided respectively with an'internally-toothed ring gear and an externally-toothed pinion gearthat mesh with one another, the pinion gear being fixed to the end plate coaxially with and surrounding the mainshaft, and thereby serve to phase or register the position of the rotor with respect to the inner peripheral surface 20 as the rotor moves in its orbital motion. This gearing has the function of rotating the centre of mass of the rotor in a circular path of radius r and at twice the mean angular velocity of the rotor apices, reacting against the inertial forces of the rotor and thereby taking the positioning load that would otherwise be applied to the apex portions of the rotor.

In a mechanism in accordance with the invention the necessary guide connection between the rotor and the casing 10, in order to ensure that the rotor is guided in the required motion relative to the casing, is produced by two freely relatively-sliding

bearing guide surfaces

46 and 48 provided respectively on the casing and rotor. In this particular embodiment the rotor guide surface 48 is constituted by the inner periphery of a recess 50 in one side wall of the rotor, while the casing guide surface 46 is provided by the external periphery of a core guide member 52 fixed to the end plate 14 and protruding into the recess 50. The

surfaces

46 and 48 are symmetrical about their respective axes and one of them must be the minimum boundary figure that is circumscribed by the other in the required orbital motion of the rotor within the casing. It is also an essential condition for this embodiment that one of the surfaces shall be shaped to conform to a specific mathematical curve which will result in a two-lobed oval-like form for that surface, so that the two co-operating guide surfaces will be operative to provide the necessary restraint and guidance between the relatively movable parts.

The rotor internal guide surface 48 has the form of an equilateral triangle contained within the shape of the rotor external periphery. It is then found that the corresponding casing guide surface 46 of the core guide member is an oval with major and minor axes parallel respectively to the minor and major axes of the casing epitrochoidal surface 20. Side seals (not shown) will be provided which co-operate with the apex seals to seal off the variable-volume working chambers from one another and from the remainder of the chamber 18. The construction of such side seals will be known to those skilled in the art.

A recess 51 similar to the recess 50 is provided in the other rotor side wall for balance, but may instead or in addition provide a guide connection surface.

One of the essential parameters to be considered for rotary mechanism of the type to which this invention applies is known as the K factor, which is the ratio 2r,/r where 2r, is the maximum rotor .radius and r is the eccentricity thereof. .I will show that rotary engines previously proposed have operated with K values for the chamber of greater than 6, usually about 7, while I am able with my invention to provide a K value preferably of 5, which will be shown to have very substantial design advantages.

FIGS. 2 to 5 show some of the different relative positions that are occupied by the rotor in the chamber 18 (one of the lobes being indicated by a dot so that its movements are more easily followed) and the corresponding relative positions occupied by the core guide surface 46 in engagement with rotor guide surface 48. It is difficult to make drawings at this small scale which will allow illustration of the exact relation of the guide surfaces 46 and 48 to be visually observed, since the clearances obtained frequently are very small. To facilitate explanation of the actual sequence of events, I use the term indexing to indicate that three places on surface 48 are in contact with surface 46, while I use the term guiding to imply that only two places of contact exist. Small circles shown on the rotor face are indicators of contact place locations when K=5. Thus in the relative positions illustrated by FIGS. 2 and 5 the rotor is indexing, while in all other positions the rotor is controlled by guiding in its dynamic motion. On the other hand if K=6 or any larger value the rotor is indexing in all positions. In both control modes rotor stability is preserved. Since the shape of the surface 46 is that generated by the movement of the surface 48 in the required motion, then the rotor is constrained to follow only that motion, resulting in an ordered sequence of relative sliding motion in which Zero sliding or even some retrogression is possible during the operation of the engine or compressor.

The apex seals 40 are required to provide the necessary sealing under the extremely arduous conditions encountered in a rotary engine, and the development of such seals has been crucial in the production of a commercially acceptable engine. FIG. 7 shows in crosssection a particularly advantageous seal structure wherein two axially-extending seal members 54, of what can be described as of boomerang transverse cross-section, have their two convex faces abutting one another, with corresponding outer end parts extending radially from the rotor and with corresponding inner end parts thereof engaged in a respective axiallyextending longitudinal slot 56. The innermost edge of each member 54 is provided with a suitable gas seal 57 and gas-conveying passages 58 lead from an opening 59 in a respective rotor face 36 to the bottom of the opposite slot.

If it is assumed for example that the rotor is rotating clockwise as seen in FIG. 2, then the surface 36a is the leading surface with respect to its associated seal. The pressurised gas in the respective working chamber will flow through the respective passage 58a to the connected slot 560 and force the seal member 54a radially outwards in its slot in the direction to reduce, or at least maintain, the leaning angle (i.e., the angle of inclination of the seal to the stator wall) at a predetermined value. Assuming that the gases at the face 36a are the expanded igniting gases then as the seal passes over the cusp of the casing epitrochoidal inner wall, the gasses will now be exhausted from the passage 58a by the engine exhaust action while pressurised gas will be applied through the passage 58b, reversing the direction of the gas action on the seal.

It can be shown that a single vertical seal would have a maximum leaning angle of 37, whereas an angle of less than 30 is desired; a seal in accordance with the invention is operable with angles no greater than 22.

The seal is lubricated automatically by means of a ball valve 60 operative in a radial bore 62 and connecting a space 64 between the abutting seal member faces with the interior space 66 of the rotor. During portions of the rotor motion centrifugal force will be effective to force oil through the passage 62 past the open ball valve to the space 64 and thence between the seal members 54; upon reversal of the force during other parts of the motion the ball valve closes to prevent drainage of oil from the space 64.

In the interest of establishing a valid basis for comparison of my guidance means with existing means it is necessary to consider the mathematical foundation which supports each of them.

It is possible to avoid misunderstanding which may occur when different K factors are used for designing the guidance means and fixing the size of the rotor. The analysis is no less general in its conclusion by applying the simplifying condition that the same K factor is assumed to apply.

The geometry of the epitrochoid is elaborated in Norbyes book, and his statement of the necessary ratio of the annular ring gear to the reaction pinion gear of 3:2, has also been mentioned earlier. By geometeric construction the annular gear has a radius r and the reaction gear radius r r and their necessary relation results in the equality:

In a three-lobed rotor based on an equilateral triangle the length of the longest radius must always be twice that of the shortest radius r and since K 2r /r the above result is that k 6.

A requirement I believe that must be met in practice is illustrated by FIGS. 8 and 9, which show the internal epitrochoidal paths generated by the short radius of the rotor triangle at is point of intersection with the midpoint of one side of the rotor triangle for two different ratios of a and b, where a is the major axis and b is the minor axis. The reversal of motion indicated by FIG. 8 cannot take place, since it would involve retrogression of the pinion in its engagement with the ring gear, and would result in jamming or even stripping thereof. The motion illustrated by FIG. 9 is therefore a limiting condition for a Wankel type engine, establishing the relation tha must be satisfied in the design of this ring gear and pinion, since (1) (n e)/( 1 H) 2 in which again the value of r r /3 as stated above.

The epitrochoidial path of the generating point on the periphery of the annular ring is illustrated by FIG. 9, in which a simple cusp occurs at each end of the short axis and represents an angular change in motion but not a retrogade motion. Thus the mathematical solution is confimed by the physical impossibility of such reversal occurring at place of engagement of the gear teeth. Having obtained the actual K factor for conventional guidance means it is possible to find solutions for all proposed design applications. For example the present generation of rotary engines is operative with a k factor that usually is about 7 in respect to the epitrochoidal body, while the guidance system is diminished in size to make its effective K factor equal to 6.

This problem does not arise with the guidance system of this invention, since the engagement between the guidance members is by sliding engaging surfaces, which will permit some retrograde motion, as illustrated by the curve of FIG. 8. It is thereforee possible to construct a mechanism in accordance with the invention with a K value lower than ,6, which is in itself a substantial design advantage.

An analysis of the rotary engines at-presentfcorhmercially available shows that all of 'them-thave anepitrochoidal chamber of K-factor much greater than 6, and the figures which I have been able to obtain appear to show a range of K-factor' from about 6.73 to about 7.14. It is at present believed that a probable reason for this is that, as is illustrated by FIG. 9, a K factor of 6 represents a unique value for the universally used three-lobed rotor and two-lobed stator, which involves stationary or almost stationary relative motion between the rotor and stator twice for each of three points on the rotor midway between the apices, making a total of six occasions in each rotation of the rotor. This theoretical observation correlates with the practical observation that as the K factor decreases toward the value 6 there is a tendency for the rotor to flutter" or chatter, indicating severe instability in its motion. It can be shown that for a k value of 6 the period of stationary or near stationary motion can extend over an angle as great as ten degrees on each occasion. A practical result of this particular flutter or chatter instability, besides the objectionable noise, vibration and possible damage to the bearings, is a breakdown of the lubricating oil film on the stator surface and consequent scoring and severe damage thereto.

An examination of FIG. 8 will show that, although there are six reversals of motion in each rotor revolution, these do not involve intermediate instable unique locations, but instead take place smoothly and progressively. As explained above the gear type guidance means used hitherto cannot function at a K value other than 6, and therefore it has never been possible with suchengines to pass beyond this highly unstable value to the more stable and preferred value of 5.

The mechanism illustrated by FIGS. 2 to has a K value of 5 and, as described, the small circles show the contact locations for the guidance surfaces for this value. As explained, although the rotor only is ben'g indexed at two locations, being the two locations at which reversal of motion takes place, and is being guided at all other locations, rotor stability is assured during the entire cycle of each rotation.

In general mechanism in accordance with this invention may employ any value of K factor contained within the range K at infinity to K equal 5 avoiding the apparently uniquely unstable value 6. As a practical matter useful power is concentrated in a limited range where k is not greater than 10. Also in practical terms the preservation of a stable pattern of motion must be sustained. By referring to FIGS. 2 and 5 it can be seen that there are a maximum of three points of contact betweeen the rotating and the fixed surfaces. The positions of the rotor show that the extreme end points of the fixed guide surface as well as one point on its short axis are in simultaneous contact with surfaces on the rotor. It can be inferred that this condition confers an exact indexing function on the guidance system which is necessary to preserve stability. A limit value for k for mechanisms of this invention can be obtained by solving the general equation for the core guide surface with the rotor in the position of FIGS. 2 or 5. The known relations are that when qb 17/ 3 the valueof x 0, where x is the abscissa. The equation is x [(K -4)+2 cos 2 4)] (r cos 4)) (l/K) and O K4-l therefore K 5 Likewise it can be deduced that stability is also preserved for all other positions, in view of the nature of the general equation, within the limits specified, namely that (l) the curve is a continuous function between the ends of its major axis; (2) it has no singular points or inflections between these limits; and (3) it is symmetrical about its major axis. The rotor can be shown to have balanced relationship of dynamic and mechanical stability, since the path of the rotors centre of gravity is in uniform circular motion under continuous surveillence of two opposed surfaces providing guidance with mechanical exactitude.

The effect of this possible reduction in K factor is illustrated by FIGS. 10 and 16, which show graphs of computations involving four cycle internal combustion engines of K factors from 5 to 7. In each case the following limits are used to permit direct comparison:

a. Compression ratio is 10 and is constant b. Rotor is measured as an equilateral triangle with c. The rotor short radius is r d. The rotor long radius is 2r e. The radius of eccentricity r in terms of K is 2r,/K

f. Rotor width is subject to designers choice, but for these examples its specific value is fixed as 3r l/K g. Displacement volume V h. Volume of chamber 18 absolute volume V i. The equation for V 241rr /K (K +3) j. The equation for V 80 fin /K FIG. 10 shows the increase in rotor surface area and working stroke, both of which are functions of K, with decrease of K, while FIG. 11 shows the increase in displacement volume V of the rotor (equivalent to piston displacement in a pistion engine) compared to the increase in total available volume in the epitrochoidal chamber 18. FIG. 12 combines the results of FIGS. 10 and 11 and shows that three rotors of K 5 should be capable of the same output as four rotors of K 7.

FIGS. l3to 16 show the expected performace of engines of the same size, but having differing K factors. FIG. 13 plots the value of V which is in this example a constant, the load factors causing friction (which are found to correspond to V and the relative radii of the rotating parts. FIG. 14 is a plot of the gross power factor and the value of V is a measure of this, since the compression ratio is constant. FIG. 15 shows the friction power loss computed using the factors of FIG. 11, and the net power factor N which is the result of subtracting friction power loss from gross power. It will be seen than N at K 7 has the relative value 1.0, while at K 5 it has become 1.6, so that on this basis two rotors of K 5 should have the net power output of three rotors of K 7. The efficiency factor of an engine is an indication of the power to be obtained from a unit quantity of fuel, and is expressed by the relation N/V A plot of this factor is shown in FIG. 16. The increasing factor shows that increased power is obtained per unit size of engine as K is decreased from 7 to 5.

At this time I am not aware of any discussion of the problem of an adequate performance rating formula which would serve as a standard of comparison between different rotary mechanisms. This problem differs from the subject of the comparison of rotary mechanisms with piston type mechanisms, which has been treated in detail. The increased scope for improvement in rotary mechanism design has disclosed the need for a standard rating formula, which will be adequate as a guide to and a measure of the progress in rotary mechanism development.

A formula is required to measure the efficiency with which the available volume is utilized for useful work. It is a noteworthy feature of a mechanism in accordance with the invention that substantially all its internal volume appears to be available for the work cycle, as though its moving parts had vanished. This entire internal volume is called Absolute Volume for that reason and is denoted as VT. The displacement volume must take into account the compression ratio, (denoted by the letter n) and is termed V,, The number of power impulses is three per rotor revolution. Then Absolute Volumeteric Efficiency Ratio is given by:

Using the convention set out above and with n=l0, the tabulation of the ratio as a percentage is:

K=7 K=6 K=5 s, 74.0% 84.8% 98.5%

If a compression ratio of 8.8 is employed when the K factor is 5, then 6 100 percent, showing that such a ratio theoretically is obtainable in a practical mechanism.

The invention is applicable to mechanisms which are engines or pumps or compressors, and the engines may be of any known cycle, such as 2 or 4 cycle, with or without compound cycles or supercharging. More than one rotor may be mounted on a single shaft and units may be employed in multiples. The engine may be of internal or external combustion type.

I claim:

1. A rotary mechanism comprising a body, a shaft mounted by the body for rotation about a corresponding axis, the body providing an internal chamber having an internal peripheral surface of two-lobed epitrochoidal crosssection perpendicular to and symmetrical about the said shaft axis, a three-lobed rotor of triangular cross-section mounted within the chamber for rotation about an axis displaced from and parallel to the said shaft axis, eccentric means connecting the shaft and the rotor for transmission of rotation between them, the rotor being symmetrical about its own axis and having three circumferentially-spaced apex portions in sealing engagement with the said chamber internal peripheral surface to form three working chambers between the rotor external peripheral surface and the chamber surface that vary in volume upon relative rotation of the rotor and the chamber, and guidance means for guiding the rotor in the required motion relative to the casing comprising a first essentially triangular guide surface movable with the rotor, symmetric about the rotor axis, and parallel to the rotor axis and a second guide surface movable with the body, symmetric about the shaft axis, and parallel to the shaft axis, the guide surfaces being in relatively-sliding en gagement with one another, the said second surface being of the oval shape generated by the said first surface in their required relative motion and having its major and minor axes parallel respectively to the minor and major axes of the internal body surface.

2. A rotary mechanism as claimed in claim 1, wherein the first surface is provided by a recess in the rotor and the second surface is provided by a member extending into the said recess.

3. A rotary mechanism as claimed in claim 2, wherein the said guidance means has a K value of about 5.

4. A rotary mechanism as claimed in claim 3, and comprising a rotary engine wherein the said internal chamber of the body and the rotor have a K value of 5.

5. A rotary mechanism as claimed in claim 1, wherein the said guidance means has a K value of about 5.

6. A rotary mechanism as claimed in claim 5, and comprising a rotary engine wherein the said internal chamber of the body and the rotor have a K value of 5.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,600 Dated May 20, 1975 Inventor s Herbert Lewis Gray It is certified that error appears in the ab0veidentified patent and that said Letters Patent are hereby corrected as shown below:

In the drawings, Sheet 1, Fig. 1, reference lines 22 should be applied to indicate vertical section through peripheral part 12.

Column 6, line 26, the formula "3r 2 (r r should read l l e --2r 3 (r r Column 8, line 29 the portion of the formula reading "247Tr K (K 3)" should read --24'rfr (K 3)/K Change the title from "GUIDANCE MEANS FOR A ROTARY ENGINE OR PUMP" t0 -'ROTARY ENGINES AND PUMPS WITH GEARLESS ROTOR GUIDANCE MEANS- Signed and Scaled this Thirty-first Day of May 1977 [SEAL] RUTH c. MASON c. MARSHALL DANN AN J IX Office Commissioner oflarents and Trademarks

Claims

1. A rotary mechanism comprising a body, a shaft mounted by the body for rotation about a corresponding axis, the body providing an internal chamber having an internal peripheral surface of twolobed epitrochoidal cross-section perpendicUlar to and symmetrical about the said shaft axis, a three-lobed rotor of triangular cross-section mounted within the chamber for rotation about an axis displaced from and parallel to the said shaft axis, eccentric means connecting the shaft and the rotor for transmission of rotation between them, the rotor being symmetrical about its own axis and having three circumferentially-spaced apex portions in sealing engagement with the said chamber internal peripheral surface to form three working chambers between the rotor external peripheral surface and the chamber surface that vary in volume upon relative rotation of the rotor and the chamber, and guidance means for guiding the rotor in the required motion relative to the casing comprising a first essentially triangular guide surface movable with the rotor, symmetric about the rotor axis, and parallel to the rotor axis and a second guide surface movable with the body, symmetric about the shaft axis, and parallel to the shaft axis, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being of the oval shape generated by the said first surface in their required relative motion and having its major and minor axes parallel respectively to the minor and major axes of the internal body surface.