US3891357A

US3891357A - Rotary mechanism of the type having a planetating rotor

Info

Publication number: US3891357A
Application number: US466634A
Authority: US
Inventors: Robert C Davis; Winthrop B Pratt
Original assignee: Curtiss Wright Corp
Current assignee: Rotary Power International Inc
Priority date: 1974-05-03
Filing date: 1974-05-03
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24

Abstract

The rotary mechanism has a housing defining a cavity in which a rotor is eccentrically supported for planetary movement in the cavity. The housing is provided with opposite end walls each of which comprise outer portions and separate central portions which are detachably secured to their associated outer wall portions. At least one of the central portions is so formed as to provide at least one axial recess extending from the housing cavity. This recess coacts with an axially extending rotor hub portion to receive the latter therein. The hub portion extension carries an internal ring gear thereby enabling a rotor bearing to have a size substantially equal to that of the rotor or larger. The rotor hub portion also carries in its end faces oil seal rings which bear against the inner surface of the associated central portion, while the side seal strips, carried in each of the rotor faces, bear against the inner surface of the outer housing portions.

Description

Davis et a1.

[ ROTARY MECHANISM OF THE TYPE HAVING A PLANETATING ROTOR [75] Inventors: Robert C. Davis, Ramsey; Winthrop B. Pratt, Haledon, both of NJ. [73] Assignee: Curtiss-Wright Corporation,

Wood-Ridge, NJ.

[22] Filed: May 3, 1974 [21] Appl. No.: 466,634

[52] U.S. Cl 418/61 A; 418/83; 418/142 [51] Int. Cl......F01c 1/02; FOlc 19/00; F040 27/00 [58] Field of Search 418/61 A, 83, 94, 104, 418/142; 123/801 [56] References Cited UNITED STATES PATENTS 2,988,065 6/1961 Wankel et a1 418/61 A 3,112,870 12/1963 Bentele 418/61 A 3,125,996 3/1964 Hoschele... 123/845 3,213,837 10/1965 Keylwert 418/91 3,333,763 8/1967 .lungbluth et a1. 418/61 A 3,369,740 2/1968 Abcrmeth 418/61 A In ury! 1 1 June 24, 1975 Primary E,\'aminer-John J. Vrablik Attorney, Agent, or Firm-Arthur Frederick; Victor D. Behn [5 7] ABSTRACT The rotary mechanism has a housing defining a cavity in which a rotor is eccentrically supported for planetary movement in the cavity. The housing is provided with opposite end walls each of which comprise outer portions and separate central portions which are detachably secured to their associated outer wall portions. At least one of the central portions is so formed as to provide at least one axial recess extending from the housing cavity. This recess coacts with an axially extending rotor hub portion to receive the latter therein. The hub portionextension carries an internal ring gear thereby enabling a rotor bearing to have a size substantially equal to that of the rotor or larger. The rotor hub portion also carries in its end faces oil seal rings which bear against the inner surface of the associated central portion, while the side seal strips, carried in each of the rotor faces, bear against the inner surface of the outer housing portions.

9 Claims, 4 Drawing Figures PATENTEDJUN24 I975 3.891-

SHEET 1 SHEET PATENTED JUN 2 4' I975 F/GZ PATENTEDJUN 24 I975 SHEET W mm ROTARY MECHANISM OF THE TYPE HAVING A PLANETATING ROTOR This invention relates to rotary mechanisms of the type having a rotor supported for planetation in a housing cavity and, more particularly, to rotors and their support for rotary mechanisms of the aforesaid type.

BACKGROUND In rotary mechanisms of the type, such as shown in the U.S. Pat. to Wankel et al., No. 2,988,065; Muller et al., No. 3,165,259; Hoschille, No. 3,125,996; and Pierce et al., No. 3,744,940 when designed to be exposed to very high fluid pressures in the working chambers (such as may occur in an expansion engine) a rotor supporting bearing of relatively large size is required. In providing a large size rotor bearing which is of a size substantially the same as the rotor width or larger than the rotor width (width being measured parallel to the axis of rotor rotation), requires the engine to be shaped to provide a K factor of about 9, which value is derived from the equation K R/e. In this equation R is the radius of the rotor which is measured from the rotor axis to an apex end, while 2 is the eccentricity of the rotor axis as measured from the axis of the mainshaft of the rotor axis (See FIG. I of the drawings). In typical rotating combustion engines the K fac' tor is usually about 7. In many rotary mechanisms of the Wankel type, it is desirable to position the side gas seal strips, in relation to the oil seal rings, so that their paths do not overlap as the rotor rotates within the housing cavity. To provide the space for a rotor support bearing of desired size, the timing gear may be provided in an axially extending hub portion of the housing end wall as is disclosed in the aforesaid Wankel et al. US. Pat. No. 2,988,065. This construction, however, poses oil sealing problems under thermal and pressure distortions to which the housing end walls are subjected during engine operation. It is this oil sealing problem which is solved by the present invention.

Accordingly, it is an object of this invention to provide a rotary mechanisms of the Wankel type, having an axially extending hub portion and a rotor bearing of at least substantially the same size as the rotor width, in which optimum oil sealing is achieved between each of the rotor faces and adjacent housing end wall.

SUMMARY The present invention therefore contemplates, in a rotary mechanism of the Wankel type, a rotor which is eccentrically supported for planetary rotation within a housing cavity defined by two end walls spaced apart by a peripheral wall and having at least one axially extending hub portion, the distal end face of which lies in a plane offset outwardly from the adjacent rotor face. A conventional internal timing gear is carried by the rotor hub portion. The hub portion of the rotor is receivable in an annular space or recess formed by a cen tral portion of the adjacent housing end wall, which central portion is separate from the other portion of the associated end wall, but is fixedly secured to the latter. The central portion has an inner sealing surface adja' cent to the distal end face of the rotor hub portion. The interstices between the sealing surface and distal end face is sealed to prevent the passage of lubricant radially outwardly through such space by an oil seal means carried in the rotor end face. The central portion of the end wall is less affected by the temperature and pressure factors imposed on the mechanism since the cen' tral portion is a separate member from the other portions of the housing end wall. Therefore the sealing surface can be made and maintained flat and smooth. Also, the centul portion may be shimmed so as to present such sealing surface in proper planar relation to the distal end face of the rotor hub portion and the orbital path of the oil seal means.

In another aspect of the invention the chamber formed between the rotor hub extension and the end walls may be provided with means for directing cooling liquid against the rotor face.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view through a rotary mechanism of the Wankel type having a rotor and housing in accordance with the invention;

FIG. 2 is a perspective view of the rotor shown in cross section in FIG. 1;

FIG. 3 is a transverse cross sectional view through the rotary mechanism of FIG. 1 with parts of the rotor removed for illustration purposes; and

FIG. 4 is a fragmentary view similar to FIG. I showing a modified rotary mechanism which provides a rotor hub of larger dimension on one side so as to pro vide adequate space for withdrawal of heated cooling liquid.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to the drawings, the reference number 10 generally identifies a rotary mechanism of the Wankel type such as disclosed in the US Pat. to Wankel et al., No. 2,988,065. The mechanism 10 generally comprises a housing 12 which defines a cavity 14 and within which a rotor 16 is supported for planetary movement on an eccentric 18 of a mainshaft 20.

The housing 112 comprises two

end walls

22 and 24 spaced apart and secured to an intermediate wall 26 by suitable means, such as a plurality of bolts 26 (only one of which is shown). The intermediate wall has an inner peripheral surface 28 of epitrochoidal configuration and so formed that cavity 14 has a two-lobe profile. In accordance with this invention,

end walls

22 and 24 have

outer portions

30 and 32, respectively, and inner central portions 34 and 36, respectively. Also,

outer wall portions

30 and 32 have bores 38 which are aligned and of large size relative to the diameter of mainshaft 20. The bores 38 are closed by central portions 34 and 36 each of which central portions has a peripheral flange portion 40 forming a shoulder 42 dimensioned to abut the peripheral surface of the associated bore 38 with flange portion 40 in abutment against the associated outer surface of

outer portions

30 and 32. Each of the central portions 34 and 36 is secured, at its flange portion 40, to

outer portions

30 and 32, respectively, by a plurality of spaced bolts 44. The central portion 36 is so dimensioned that its inner surface 46 defines, with inner surface 48 of outer portion 32, a recess 50 which constitutes an axial extension of cavity 14. Similarly, central portion 34 may be, as shown, dimensioned such that its inner surface 52 defines in relation to the inner surface 54 of outer portion 30 of end wall 20 a recess 56 which also forms an axial extension of cavity I4.

To support the mainshaft 20 for rotation, a bearing support 58 is secured by bolts 60 or other suitable means to central portion 30 of end wall 22, while a timing gear bearing support member 62, having a pinion gear 63, is secured by bolts 64 or other suitable means to central portion 36 of end wall 24.

Coacting with the housing 12, according to this invention, rotor 16 (best shown in FIG. 2) is provided with an axial, outwardly extending tubular hub portion 66 which is dimensioned in length to project from the face 68 of rotor 16 and into recess 50 of the engine housing 12. The rotor 16, as shown, may be provided with a juxtaposed tubular hub portion 70 of smaller length than hub portion 66, which hub portion 70 extends from the opposite face 72 of rotor 16 into the shallow recess 56. An internal timing ring gear 74 is supported in the distal end portion of hub portion 66. The ring gear 74 may be made integral with rotor 16, as is shown, or be a separate member secured in a suitable manner to hub portion 66. The ring gear 74 is disposed in meshing relationship with pinion gear 63 to thereby maintain, as rotor 16 planetates, the angular relationship of rotor 16, mainshaft 20 and housing 12.

The rotor 16, as is conventional, carries in its

faces

68 and 72 side seal strips 76 and 77 which engage the

inner surfaces

48 and 54 of

outer portions

24 and 22, respectively. The seal strips 76, along with apex seals 78 and seal pins 80, serve to maintain the working chambers, defined by the rotor flanks 82, out of communication with each other and minimize gas leakage from the working chambers. To prevent oil leakage from the mainshaft bearings and timing gear regions to the working chambers, each of the end faces of hub portions 76 and 70 carry a seal ring 84 and 86, respectively. The oil seal rings 84 and 86 respectively bear against the inner surfaces 46 and 52 of the respective central portions 36 and 34. The oil is supplied to or removed from the bearing regions of mainshaft 20 and the region of timing gears 63 and 74 via recesses 41 and ports 45 which form part of a lubrication system which may be of the general type such as disclosed in US. Pats. to Bentele et al., No. 3,176,915 or Jones, No. 3,26l ,542.

By reason of the aforementioned construction of rotor 16 and housing 12, several functional advantages are achieved. First, the bearing 90 surrounding the eccentric 18 which supports rotor 16 is of a size at least corresponding substantially to the width of rotor 16 or can be made larger than the rotor width and thereby capable of withstanding the forces imposed on the rotor by high pressure gases in the working chambers. Secondly, to meet a specific design requirement, the rotor and housing width can be reduced without reducing bearing sizes so that the bearing can accept the anticipated loadings. Thirdly, oil leakage is minimized because surfaces 46 and 52 of central portions 36 and 34, respectively, can be made flat and smooth so that seal rings 84 and 86, which bear against such surfaces, will maintain an effective seal. This effective oil seal is also insured since surfaces 46 and 52 are independent of

surfaces

48 and 54 against which the seal strips 76 and 77 bear. Manifestly, if necessary, central portions 34 and 36 when secured to their respective outer portions and 32 may be shimmed and thereby positioned in planes independent of

surfaces

48 and 54 to insure optimum and continuous contact of seal rings 84 and 86 as they planetate against their respective surfaces 46 and 52. Also, this optimum sealing effectiveness can be maintained since surfaces 46 and 52 are less affected by the thermal and pressure distortions of

outer portions

30 and 32.

To avoid the overlapping of the orbital paths of oil seals 84 and 86 and their associated side seal strips 76 and 77, the mechanism 10 is proportioned by a K factor of about 9, which K factor is derived from the equation K R/e. In this equation, as shown in FIG. 1, R is the radius of rotor 16 measured from the rotor axis X to the apex end of the rotor while 2 is the eccentricity of the rotor axis X measured from the mainshaft axis Y on the housing cavity 14.

As best shown in FIG. 3, rotor 16 may be cooled by mounting one or more nozzles 92 in

end walls

22 and 24 to direct streams of cooling liquid, e.g. water from a suitable source thereof such as the water jackets, against one or both rotor faces 68 and 72. As shown each of two nozzles 92 for each rotor face is positioned to discharge cooling liquid through its associated surfaces 48 and '54 of

outer wall portions

32 and 30 and is located in the area not swep or encroached by seal rings 84 and 86 and their associated seal strips 76 and 77 (hereinafter referred to as the no-wear triangle" zones). As fully disclosed in the US. Pat. to Bentele No. 3,1 12,870, in a two-lobe trochoidal housing configuration, such as shown, there are on each side of the rotor two no-wear triangle zones. With each of the nozzles 92 positioned in the no-wear triangle zone, cooling liquid is trapped between the seal rings and associated seal strips and is prevented from entering the oil system or the working chambers.

In the rotary mechanism of the expander type having, as shown in FIG. 3, two high pressure gas inlets 100 and exhaust ports 102 in

end walls

22 and 24 so located as to communicate with the space between the paths of seal rings 84 and 86, and their associated seal strips 76 and 77 as rotor 16 rotates, heated cooling liquid collected in

recesses

50 and 56 is discharged therefrom through exhaust ports 102. In other rotary mechanisms, where discharge of heated cooling fluid through the working chamber discharge port is undesirable, then, as shown in FIG. 4, discharge passageways 104 may be provided in

end walls

22 and 24 to conduct the heated cooling fluid from

recesses

50 and 56. To provide sufficient space for a discharge passageway 104 where cooling is desired along both faces of rotor 16, hub portion and central portion 34 may be dimensioned to increase the size of recess 56 and thus provide the room for a discharge passageway 104. Since the rotary mechanism in FIG. 4 essentially only differs from the rotary mechanism shown in FIGS. 1 and 2 in dimensions, the same reference numbers for like parts are employed in both rotary mechanisms.

The leakage of cooling liquid from

recesses

50 and 56 may be prevented by suitable seals or gaskets, such as O-ring seals carried in shoulders 42 of central portions 34 and 36.

It is believed now readily apparent that the present invention provides a rotary mechanism having an increased bearing load capacity and, therefore, capable of operation with relatively high gaseous pressures in the working chambers and, at the same time, provides optimum oil sealing, rotor cooling being also provided, if necessary.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention, as the same will now be under stood by those skilled in the art.

What is claimed is:

1. An improved rotary mechanism of the type having a housing comprising two end walls spaced in substantial parallelism by an intermediate peripheral wall to define therebetween a cavity and having a rotor supported for planetary movement within said cavity on an eccentric portion of a mainshaft supported for rotation in said two end walls, the improvement comprising a. at least one of said end walls consisting of an outer portion and a separate central portion detachably secured to said outer portion;

b. said outer portion having a first inner sealing surface partly defining said cavity;

c. said central portion having a second inner sealing surface located radially inwardly of said first inner sealing surface and being so dimensioned and secured to said outer portion that the second inner sealing surface is in a plane substantially parallel to and axially outwardly offset from the plane of said first inner sealing surface to thereby define an axial recess communicating with said cavity;

d. the rotor having a face portion disposed in close spaced substantially parallel relation to said first sealing surface and having a tubular hub portion extending into said axial recess and with an end face in close spaced substantially parallel relation with said second inner sealing surface;

e. side gas seal means disposed to seal the interstices between said rotor face and said first seal surface as the rotor orbits within said cavity;

f. lubricant passageway means disposed radially inwardly of said end face of the tubular hub portion and said second inner surface for conducting oil to or from the eccentric portion of the mainshaft; and

g. side oil seal means disposed to seal the interstices between said end face of said tubular hub portion of the rotor and said second inner sealing surface as the rotor orbits within said cavity and thereby prevent the escape of oil from said lubricant passageway means.

2. The mechanism of claim 1 wherein said oil seal means is carried in the end face of said tubular hub portion of the rotor.

3. The mechanism of claim 1 wherein said side gas seal means and said oil seal means are carried by said rotor.

4. The mechanism of claim 1 wherein said gas seal means includes a plurality of side seal strips disposed adjacent the periphery of the rotor and said oil seal means is a ring means.

5. The mechanism of claim 1 wherein said tubular hub portion rides on a bearing of a width at least substantially that of the space between said two end walls.

6. The mechanism of claim 1 wherein each of said end walls consist of an outer portion and a separate central portion detachably secured to the associated outer portion.

7. The mechanism of claim 6 wherein each of said central portions are each dimensioned and secured to the associated outer portions so as to define with the latter an axial recess communicating with the cavity and wherein said rotor has two juxtaposed tubular hub portions each of which extends into an adjacent recess.

8. The mechanism of claim 1 wherein cooling means separate from said lubricant means is provided in said one end wall to discharge cooling liquid into said axial recess and for impingement against said rotor. I

9. The mechanism of claim 8 wherein said cooling means is a nozzle disposed to direct a stream of cooling

Claims

1. An improved rotary mechanism of the type having a housing comprising two end walls spaced in substantial parallelism by an intermediate peripheral wall to define therebetween a cavity and having a rotor supported for planetary movement within said cavity on an eccentric portion of a mainshaft supported for rotation in said two end walls, the improvement comprising a. at least one of saId end walls consisting of an outer portion and a separate central portion detachably secured to said outer portion; b. said outer portion having a first inner sealing surface partly defining said cavity; c. said central portion having a second inner sealing surface located radially inwardly of said first inner sealing surface and being so dimensioned and secured to said outer portion that the second inner sealing surface is in a plane substantially parallel to and axially outwardly offset from the plane of said first inner sealing surface to thereby define an axial recess communicating with said cavity; d. the rotor having a face portion disposed in close spaced substantially parallel relation to said first sealing surface and having a tubular hub portion extending into said axial recess and with an end face in close spaced substantially parallel relation with said second inner sealing surface; e. side gas seal means disposed to seal the interstices between said rotor face and said first seal surface as the rotor orbits within said cavity; f. lubricant passageway means disposed radially inwardly of said end face of the tubular hub portion and said second inner surface for conducting oil to or from the eccentric portion of the mainshaft; and g. side oil seal means disposed to seal the interstices between said end face of said tubular hub portion of the rotor and said second inner sealing surface as the rotor orbits within said cavity and thereby prevent the escape of oil from said lubricant passageway means.

8. The mechanism of claim 1 wherein cooling means separate from said lubricant means is provided in said one end wall to discharge cooling liquid into said axial recess and for impingement against said rotor.

9. The mechanism of claim 8 wherein said cooling means is a nozzle disposed to direct a stream of cooling liquid against said rotor.