US2979042A

US2979042A - Seal vent arrangement for rotating combustion engines

Info

Publication number: US2979042A
Application number: US6968A
Authority: US
Inventors: Bentele Max
Original assignee: Curtiss Wright Corp
Current assignee: Curtiss Wright Corp
Priority date: 1960-02-05
Filing date: 1960-02-05
Publication date: 1961-04-11
Anticipated expiration: 1978-04-11
Also published as: BE599739A; GB906387A; CH391378A

Description

April 11, 1961 M. BENTELE 2,979,042

SEAL VENT ARRANGEMENT FOR ROTATING COMBUSTIQN ENGINES Filed Feb. 5, 1960 2 Sheets-Sheet 1 INVENTOR. MAX EIENTELE.

ATTDRNEY April 11, 1961 M. BENTELE 9,0

SEAL VENT ARRANGEMENT FOR ROTATING COMBUSTION ENGINES Filed Feb. 5, 1960 2 Sheets-Sheet 2 INVENTOR. MAX EE N T E. LE

BYZZZ'D FIX ATTURNEY SEAL VENT ARRANGEMENT FOR ROTATING COMBUSTION ENGINES Max Eentele, Ridgewood, N.J., assignor to (Zurtiss-Wright Corporation, a corporation of Delaware Filed Feb. 5, 1960, Ser. No. 6,968

12 Claims. (Cl. 123-8) The invention relates to rotary mechanisms of the type illustrated in copending application Serial No. 774,517 filed November 17, 1958 and is particularly directed to a seal vent arrangement for such mechanisms.

Such rotary mechanisms comprise an outer body having axially-spaced end walls interconnected by a peripher- 211 wall to form a cavity therebetween and an inner body or rotor is received within said cavity between the cavity end walls. The inner surface of said peripheral Wall preferably is parallel to the axis of said cavity and, as viewed in a plane transverse to said axis, said inner surface has a multi-lobed profile which preferably is an epitrochoid. The axis of said rotor is parallel to but spaced from the axis of the outer body cavity and said rotor has anally-spaced end faces disposed adjacent to said outer body end walls and also has a plurality of circumferentially-spaced apex portions. The rotor is rotatable relative to the outer body such that said apex portions continuously engage the inner surface of said peripheral Wall to form a plurality of Working chambers between said rotor and peripheral wall which vary in volume, during engine operation, as a result of relative rotation of said rotor and outer body.

By suitable arrangement of porting such rotary mechanisms may be used as fluid motors, compressors and combustion engines. The invention will be described in connection with a combustion engine although as will be apparent the invention is not so limited. Such rotary mechanisms when used as combustion engines include an intake port for admitting a fuel-air mixture to said chambers, an exhaust port for said chambers and suitable ignition means such that during engine operation the working chambers of the engine have a cycle of operation which includes the four phases of intake, compression, expansion and exhaust. As described in said copending application this cycle of operation is achieved as a result of the relative rotation of said inner rotor and outer body and for this purpose both said inner body and outer body may rotate or one, preferably the inner body, may rotate while the outer body is stationary.

For efficient operation the engine working chambers should be sealed. For this purpose an effective apex seal means is provided along each apex portion of the rotor for engagement with the peripheral wall of the outer body. In addition, end face seal means for the combustion gases are carried by the rotor, preferably at each end face and preferably adjacent to the periphery of the rotor end face, said end face or peripheral seal means providing a substantially continuous contact area in sealing engagement with the adjacent end wall of the outer body adjacent to the rotor periphery so as to encircle the rotor axis. Also an oil seal ring means is carried by each rotor end face radially inwardly of said rotor peripheral seal means and adjacent to and radially outwardly of the rotor journal bearing, for sealing engagement with the adjacent end wall of the outer body.

The peripheral seal means at an end face of the rotor is a face-type seal and therefore is not 100% effective so that during operation of the rotary mechanism some gas flow will take place across this seal from the working chambers and into the space between said peripheral seal means and the adjacent oil seal ring. Accordingly, a gas pressure will tend to build up between said periphera1 seal means and the oil seal ring means. If this pressure becomes excessive at one end face of the rotor it will produce an axial thrust on the rotor which may cause excessive seal pressures and friction losses at the other end face of the rotor. Also if this pressure becomes excessive at one rotor end face it might cause the gases to blow by the oil seal ring means at said end face. This is particularly objectionable in the case of a combustion engine type of rotary mechanism in that any blow by of the combustion gases causes oxidation and other deterioration of the engine lubricating oil as well as heating of said oil. Blow by of combustion gases past the rotor oil seals is also objectionable because provision of suitable breather apparatus for the escape of such gases and/ or provision of a suitable gas-oil separator then becomes necesasry. Furthermore, it is known that blow by of combustion gases in present day automotive combustion engines is a major factor in producing smog in the surrounding atmosphere.

7 An object of the present invention resides in a novel. arrangement for periodically venting, to the engine intake port, the space between the peripheral seal means and oil seal ring means at 'each rotor end face. This arrangement avoids blow by of the combustion gases into the lubricating oil and also avoids any excessive pressure, build up at the rotor end faces. In addition, by venting this space to the intake port, any unburnt exhaust products escaping from the working chambers past the peripheral seal means at the rotor end face are automatically returned to the engine intake for combustion in the engine. This latter feature makes for cleaner engine operation.

In one form of the rotary combustion engine, the engine has one intake port which communicates with the engine working chambers through an end wall of the engine outer body. In this form of the engine, the space between the peripheral seal means and oil seal ring means at the rotor end face adjacent to said intake port is periodically vented to said intake port as a result of the relative rotation of the engine rotor and outer body during engine operation. In accordance with the invention the rotor is provided with one or more passages passing axially therethrough and interconnecting the space between the peripheral seal means and oil seal ring means at one rotor end face with the corresponding space at the other rotor end face. With this construction each said space is periodically and simultaneously vented to the intake port during engine operation.

The engine intake port instead of opening through an end wall of the engine outer body mayopen through the peripheral wall of said outer body. In accordance with the invention, in this latter form of the engine each end wall of the engine outer body is provided with a groove so that during engine operation the space between the rotor peripheral seal means and oil seal ring means at the adjacent rotor end face is periodically vented to a working chamber while said chamber is open to the intake port whereby in this form as in the first described form of the invention said space is periodically vented tothe intake port.

7 .Other objects of the invention will become apparent upon reading the annexed detail description in connec 7 Fig. 2 is a transverse sectional view taken along line 2-2 of Fig. 1;

Fig. 3 is an enlarged perspective view of a portion of the rotor incorporated in the engine of Fig. 1;

Fig.4 is aviewsimilarto'Figsl of a-rotary combustion engine embodyingza modified form of the invention; and

Fig.5 is a fragmentary sectional view taken along line 5-5 of Fig.4.

Referring first to. Figs. 1-3 of the drawing, a rotary internal combustion engine is schematically indicated by reference numeral 10. Said engine comprises an outer body 12 having axially-spaced.

endwalls

14 and 16 with a peripheral wall 18 connected therebetween to form a cavity 20- As viewed in a planetFig. 1) transverse to the axis 22 of the cavity 20; the inner surfaceof the pe-: ripheralwall 13 of 'said cavity :having'amulti-lobed profile-which preferably is an epitrochoid. In .the specific embodiment illustratedsaid cavity'profilehas two lobes although the engine is not limited to this specific number with outwardlyarched sides. As hereinafter more fully explained," said apex portions are in sealing engagement with the inner surface of peripheral wall 18 to form a plurality .'(three as illustrated) of working chambers 32 between the inner rotor 24 and outer body 12. Each working chamber 32 includes a trough 31 formed in the adjacent peripheral face of the rotor 24. each of said troughs forming a substantial-part of the combustion space during combustion in said chamber. The geometrical axis 34 of the rotor 24-is offset from and is disposedparallel to the axis 22 of the outer body;

In the engine 10 illustrated the outer body 12 is stationary while the rotor 24 is journaled on an eccentric portion 36 of a shaft 38,-said shaft being co-axial with the geometrical axis 22 of the cavity 20--in said outer body. Upon rotation of the rotor 24 relative'to-the outer body 12 the working chambers 32 vary in volume. An

intake port 30 is provided in only one of the end walls 14 or 16 -(16 as illustrated) for admitting air and fuel into the working chambers, a spark plug 42 is provided for igniting the combustion mixture and an exhaust port 44 is provided in the peripheral wall for discharge of the exhaust gases from the working chambers 32. As more fully explained in the aforementionedcopending application, during engine operation the working chambers 32' have a cycle of-operation including the four phases of intake, compression, expansion and exhaust; said phases being similar to the strokes in a reciprocating-type internal combustion engine'having a four-stroke'cycle. In order to maintain the relative motion of the inner' rotor 24 relative to the stationary outer body an internal gear 46 is, as illustrated, secured to theinner rotor co-axially with the rotor axis 34 and is disposed in mesh with a inwardly, preferably radially, from its apex and running.

from one end face 26 to the other end face 28 in a direction parallel to the rotor. axis. Seal strip means 52 are received within each of said apex grooves 50 and "a spring 54 under each seal means 52 urges it radially outwardly so that'each said seal strip means projects beyond its groove 50 into sealing engagement with the inner surface of the peripheral wall 18.

The bottom of each apex grove 30 has an enlarged cylindrical portion at each end of the groove and an intermediate seal member 56 is slidably fitted within each such cylindrical portion. Each intermediate seal member 56 has a slot 58 for receiving the radially inner edge of the adjacent end of a seal strip means52 for sealing cooperation therewith.

Each end face 26 and 28of the inner rotor 24 has a plurality of grooves 60 therein running from one apex portion of the rotor to the adjacent apex portion and a one-piece seal strip 62 is received within each such groove. A spring 64 behind'each end face seal strip 62 urges it axially outwardly so that said strip 62 projects axially beyond the adjacent rotor end face into sealing engagement with the adjacent housingend wall. As illustrated, each end face seal strip 62 has an L-shaped crosssection with onelegbeingreceived within its groove 60 and with its oth'erdeg being parallel to the adjacent end walls i i-and i the outer body. Also each end face seal strip 62 preferably is shaped as a circular arc and is disposed adjacent to but inwardly of the rotor periphery throughout its length. The apex seal strip means 52, intermedia e seal member 56 and end face seal strips 62 preferably have a construction similar to that more fully described in applicants copending application, Serial No. 5,497, filed January. 29, 1960, and entitled Rotating Combustion Engine Seal Construction. For the purpose ofthe present invention it should be noted that the seal strips 62 and the adjacent end portions of the intermediate-seal members 56 cooperate to provide a continuous contact area in sealing engagement with the adjacent end wall of the outer body 12. This seal contact area encircles the rotor axis and provides a seal adjacent to the rotor periphery against inward flow of combustion gases between'the rotor end faces 26 and 28 and the

end walls

14 and 16.

A seal ring 66 is also disposed in a circular groove 68 ineach end face of the rotor radially outwardly of and coaxial with the journal bearing 70 for said rotor on the shaft eccentric 36'and radially inwardly of the end face seal strips 62. 'The seal rings 66 function as oil seals to prevent leakage flowof lubricating oil radially outwardly beyond said seal-rings 66 between their associated rotor Suitable spring rotor end faceto the other. The holes 74 preferably are disposed adjacentto the rotor apex portions andeach hole 74 is arranged so that each of its ends opens through a the adjacent rotor end face between'the circular seal ring 66 and'peripheral seal means provided by the seal elements-56 and 62 atsaid rotor end face.-

With this construction, as the rotor rotates during engine operation the'space' at the rotor end face 28 adjacent to the end wall 16and disposed between the seal ring 66 and the rotor end face or peripheral seal means provided by the

seal elements

56 and 62 is periodically vented to the intake port 40. In addition, since the holes 74 interconnect said space at one rotor end face with the corresponding space at the other rotor end face both said spaces are periodically vented to the intake port. This periodic venting of the space at each rotor end face between the seal ring 66 and the rotor end face periphery seal as provided by the

seal elements

56 and 62 is clearly shown by the two rotor positions illustrated in Fig. l and results from the eccentricity of the axis of the rotor' 24 relative to'the axis of the cavity 20 of the outer body 12.

As described in applicants aforementioned copending application, the total clearance between the two rotor end faces 26 and 28 and the

adjacent end walls

14 and 16 when the engine is operating preferably is quite small and for example may be of the order of one quarter of one percent of the axial width of the rotor 24. Accordingly, although the space at each rotor end face between the seal ring 66 and the seal strips 62 is continuous about the rotor axis, said space nevertheless is quite restricted. For this reason it is preferable that a plurality of circumferentially-spaced passages be provided through the rotor and in addition the end of each passage 74 at the rotor end face 28 preferably should be disposed so that as the rotor rotates said passage end periodically becomes aligned with at least a portion of the rotor intake port to communicate directly therewith. For these reasons at least one passage 74 preferably is provided at each apex portion 30 of the rotor.

The end face seals 56 and 62 obviously are not 100% effective. Accordingly, in the absence of the passages 74 combustion gas pressure might build up in the space between the end face seals 62 and the seal ring 66 at the rotor end face 26 adjacent the end wall 14 since this end wall has no intake port. If this pressure at the rotor end face 26 becomes excessive, it will produce an axial thrust on the rotor which may cause excessive seal pressures and friction losses at the other end face. Also any such excessive pressure at the rotor end face 26 might cause the combustion gases to blow by the oil seal ring 66 at said end face. Any such blow by is objectionable because it causes oxidation and other deterioration of the engine lubricating oil and also causes heating of said oil. Furthermore, excessive pressure at the rotor end face 26 may actually cause the oil seal ring 66 to lift olf the adjacent end wall 14 whereupon oil may leak into the space between said oil seal ring 66 and the adjacent seal strips 62. In addition, as previously mentioned, blow by of combustion gases past the rotor oil seals is also objectionable because such blow by necessitates the provision of breather apparatus and/or a gas-oil separator and such blow by in present day automotive engine is a major factor in producing smog.

As described in said first mentioned copending application, the engine intake port may open into the engine through the peripheral wall of outer body instead of through an end wall. Such an engine is illustrated in Figs. 4-5. For ease of understanding the parts of Figs. 45 corresponding to the parts of Figs. 1-3 have been designated by the same reference numerals but with a subscript a added thereto.

Except for the change in the location of the intake port 40a from an end wall 14a or 16a to the peripheral wall 18a the basic engine structure of Fig. 4-5 is like that of Figs. 1-3. As shown in Figs. 4-5 the end wall 16a of the outer body is provided with a groove 80 in the region of the intake port 40a. The groove 80 is disposed so that when the rotor 24a is in its position of Fig. 4 in which the intake port 40a is open to a working chamber 32a said groove 80 provides a passage in the end wall 16a which extends across an end face seal strip 62a. Hence, with the rotor 24a in the position of Fig. 4 the space adjacent to the end wall 16a between the oil seal ring 66a and the rotor

periphery seal elements

56a and 62a is vented through said groove 80 to the working chamber 32:: which is then in communication with the intake port 40a. It is apparent therefore that the groove 80 provides a passage in the outer body end wall 16a which periodically vents, to theintake port 40a, the

space between the seal ring 66a and the rotor periphery seal provided by the

elements

62a and 56a engageable with the end wall 16a. A similar groove 80 (not shown) is provided in the other end wall, corresponding to the wall 14 of Figs. 1-3, for venting to the intake port 4011 the space between the seal ring 66a and seal

elements

56a and 62a at said other end wall.

Holes 74a, corresponding to the holes 74 in the rotor 24, preferably are also provided in the rotor 24a although such holes are not needed in Fig. 4 for the aforedescribed venting purposes. However, the provision of the holes 74a insures equalization of pressure at the two end faces of the rotor 24a.

Obviously grooves, equivalent to the grooves of Fig. 4-5, 'could be provided in the end wall 14 of Fig.

1-3 in addition to or in lieu of the holes 74 for periodtake port as described, said space obviously could be vented for this purpose to the exhaust port preferably when the exhaust port pressure is a minimum. Venting to the intake port is preferred, however, for example because of its eifect on smog reduction.

While I have described my invention in detail in its present preferred embodiment it will be obvious to, those skilled in the art after understanding my invention that various changes and modifications may be made therein without departing from the spirit or scope thereof.

I claim as my invention:

1. A rotary mechanism comprising an outer body having axially-spaced end walls and a peripheral wall interconnecting said end walls to form a cavity therebetween;

having axially-spaced end faces disposed adjacent to said end walls and also having a plurality of circumferentiallyspaced apex portions for engagement with the inner surface of said peripheral wall to form a plurality of working chambers between said inner body and wall which vary in volume, during operation, as a result of relative rotation of said inner body and outer body, said outer body having an intake port and an outlet port for said chambers controlled by relative rotation of said bodies; and first and second radially-spaced seal means carried by an end face of said inner body for engagement with the adjacent end wall of the outer body with both said seal means encircling the axis of said inner body, one of said bodies having passage means other than said ports for periodically venting the space between said first and second seal means to one of said ports upon relative rotation of said bodies.

2. A rotary mechanism as recited in claim 1 in which said space is vented to the intake port.

3. A rotary mechanism as recited in claim 1 in which said space is vented to the intake port and said passage means constitutes a plurality of passages passing axially through the inner body, there being at least one such passage at each apex portion.

4. A rotary mechanism as recited in claim 1 in which said space is vented to the intake port and in which said intake port opens into said working chambers through an end wall of said outer body and said first and second seal means are carried by the end of the inner body adjacent to the other end Wall and in which said passage means constitutes at least one passage passing axially through said inner body from a point between said first and second seal means at one end face of the inner body to its other end face such that during rotation of said inner body the one end of said passage periodically communicates directly with said intake port.

5. A rotary mechanism as recited in claim 4 and including corresponding first and second seal means at the other end face of the inner body, and said inner body having at least one said passage passing axially therethrough from a point between the first and second seal means at one end face of the inner body to a corresponding point at the other end face.

6. A rotary mechanism as recited in claim 1 in which said space is vented to the intake port and in which the 7? radially." outer of-said se'al -means isdisposed adjacent and substantially-parallel to -th periphery of said rotor whereby: it extends from each-rotorapex portion to the adjacent apex-portions and the radially inner of sai'd seal means is circular and concentric with the/axis of the inner b'ody;

7. A- rotary mechanism as recited in claim 6 in which the radially outer of said seal means comprises a plurality of seal members, one at each apex portion of the inner body, and an equal numberof seal strips each extending from one seal member to an adjacent seal member, said seal members and seal strips having cooperating surfacesto providea substantially continuous seal adjacent to'the peripheryof'the inner body and encircling the axis-of said inner body.

8. A' rotary mechanism asrecited in claim-'1 in which said passage means comprises a'groove" in atleast one end wall-disposed so'that the space between' the first and second seal means 'engageable with said end walls is -periodically connected to a working chamber while said chamber'is in communication with said'one port.

9. A rotary mechanism comprising an outer body having axially spaced end walls and-'a'peripheral wall in terconnectingsaid end' walls'to form a cavity thereb'e tween; a rotatable inner body received within said cavity with its axis parallel to'butoffset from the axis of the cavity and having axially-spaced end faces disposed 'adjaof said bodieswithsaid intake port opening through I second'seal means carried by the inner body'end face remote from said intake port.

10; A rotary mechanism as recited in claim 9 in which saidpasSage'means comprises at least one passage passingaxially through the'inner body'from a point between the'firstand' second seal means 'on one end face of the innef body"toa point between the corresponding seal means on the'other end'face.

11."A rotary'mechanism as recited in claim 9 in which the radially inner of said seal'means is circular and concentric with the axis of theinner body andthe radially' outer of 'said seal means comprises a plurality of seal members, one at each apex portion of the inner body, and antequalnumber'of' seal stripseach extending'from one seal member to an adjacent seal member, said seal members and seal strips having cooperating surfaces toprovide'asubstantially continuous seal adjacent to theperiph'ery of "the inner body and encircling the axis of said'inner body.-

12; A rotary mechanism as recited inclaim'9 in which said passage means comprises a plurality of passagespassing axially through'the inner body "from a point between the first'and second seal means on one'end face'of the inner body' to a 'pointbetw'een the corresponding