US3300127A

US3300127A - Rotary piston and seal therefor

Info

Publication number: US3300127A
Application number: US433584A
Authority: US
Inventors: Yamamoto Kenichi; Osakada Sunao
Original assignee: Toyo Kogyo Co Ltd
Current assignee: Mazda Motor Corp
Priority date: 1964-02-26
Filing date: 1965-02-18
Publication date: 1967-01-24
Anticipated expiration: 1984-01-24

Description

1967 KENICHI YAMAMOTO ET AL ROTARY PISTON AND SEAL THEREFOR 3 Sheets-Sheet '1 Filed Feb. 18, 1965 Ken/chi Yamamafo Sunao Osakada MM, M z/WM ATTORN Evs Jan. 24, 1967 KENICHI YAMAMOTO ET 3,300,127

ROTARY PISTON AND SEAL THEREFOR Filed Feb. 18, 1965 3 Sheets-Sheet 2 Ken/chi Yamamoro .Sunao Osakaa'a INVENTORS ATTORNEYS 1967 KENICHI YAMAMOTO ET AL 3,300,127

ROTARY PISTON AND SEAL THEREFOR Filed Feb. 18, 1965 3 Sheets-Sheet 5 Ken/chi Yamamoro Sunao Osakada INVENTORS BY M MMZ, ZMWA ATTORNEYS United States Patent O 3,300,127 ROTARY PESTON AND SEAL THEREFOR Keniciii Yamamoto and Sunao Osakada, both of Hiroshirna-shi, Japan, assignors to Toyo Kogyo Company Limited, Hiroshima-ken, Japan Filed Feb. 18. 1965, Ser. No. 433,584 (Ilaims priority, application Japan Feb. 26. 1964, 39/1 1,814, 3/14.815; Feb. 28, 1964, 39/10,930 9 Claims. (Cl. 230-145) The present invention relates to a rotary piston internal combustion engine and particularly to a sealing device for forming a seal between a rotary piston and the end walls of the casing of the engine.

A rotary piston internal combustion engine generally consists of an annular casing having a trochoid-shaped internal peripheral wall and end walls on the opposite ends of the annular casing, which end walls have flat internal faces. A triangular rotary piston is rotatably mounted on a crank pin which is eccentrically mounted on a crankshaft which extends through the center of the combustion chamber defined by the annular casing and the two end Walls. At each apex of the rotary piston is a sealing member which forms a sealbetween the rotary piston and the annular casing and defining combustion chambers between the triangular piston and the trochoidshaped internal Wall of the annular casing. On the fiat end face of the triangular piston adjacent the outer edge of the piston is also a sealing member forming a seal between the rotary piston and the end walls of the casing. Cooling of the rotary piston during the operation of the above described engine is carried out by supplying cooling oil through apertures provided around the crank pin within the rotary piston. On the flat faces of the opposite sides of the piston, the apertures through which the cooling oil is supplied, open in the axial direction and surrounding each of the said apertures is an internal sealing ring which also forms a seal between the piston and the side walls of the casing'and maintains the cooling oil sealed within the apertures.

The problem in the engine of the above described type is that the leakage of explosive gas past the side seals at the outer edge of the end faces of the rotary piston is inevitable during the operation of the engine, and the inner seal ring surrounding the said cooling oil apertures is affected by the pressure of the leaking explosive gas and deteriorates in its effectiveness as an oil seal. There have been suggestions to install the inner sealing ring around the said cooling oil apertures with a spring means positioned behind the sealing ring within a circular groove on the piston end face to force the sealing ring outwardly against the inner surface of the end walls of the casing, but this arrangement has proved defective for sealing off the cooling oil apertures tightly because the pressure of the leaking gas is very high and the effect of the spring means behind the sealing ring is defeated by the effect of the pressure of the leaking gas during the operation of the engine.

It is an object of the present invention to provide a sealing device for a rotary piston engine which effects an air and oil-tight seal between a rotary piston and the end walls of the casing by utilizing either gas or oil pressure applied thereto.

Another object of the present invention is to form an oil-tight seal between the rotary piston and the end walls of the casing by applying the pressure of the cooling oil for the piston which is due to centrifugal force to the sealing ring, whereby the sealing effect is automatically increased in proportion to the amount of the said.

centrifugal force.

and 2'.

ice

Other and further objects of the invention will become apparent from the following specification and claims, taken together with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a rotary piston engine showing a rotary piston provided with a sealing device according to the present invention;

FIG. 2 is a longitudinal sectional view taken on the line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional view of a portion of FIG. 2 on an enlarged scale and showing the details of the sealing unit;

FIG. 4 is a fragmentary sectional view taken on line 4-4 of FIG. 3;

FIGS. 5 and 6 are cross-sectional views similar to FIG. 3 and showing modified forms of the sealing device of FIG. 3;

FIG. 7 is a fragmentary sectional view taken on line 7-7 of FIG. 6;

FIGS. 8 and 9 are cross-sectional and longitudinal sectional views, respectively, similar to FIGS. 1 and 2 of a rotary piston engine with a modified sealing device according to the invention;

FIGS. 10, 12 and 13 are fragmentary sectional views similar to FIG. 3 and showing details of modified forms of the sealing unit of FIGS. 8 and 9; and

FIGS. 11 and 14 are fragmentary sectional views taken on the lines 11-11 and 1414 of FIGS. 10 and 13, respectively.

Referring first to FIGS. 1, 2, 3 and 4, a combustion chamber a is defined within an annular casing 1 having 'an internal peripheral wall which is trochoid-shaped and two

end walls

2 and 2 at the opposite ends of the annular casing. Positioned-within the combustion chamber a is a triangular rotary piston 3 having a plurality of apexes which are moved along the internal peripheral wall of the center casing 1 during rotation of the piston. At the apexes and along the peripheral side edge between each pair of apexes of the piston are sealing

members

4 and 5. which form seals between the piston 3 and internal walls of the annular casing 1 and the end walls 2 and 2'.

Extending through the center of the combustion chamber a is a crankshaft 6 which is rotatably mounted in cylindrical crankshaft bushings 7 fixed in the end walls. Integral with the crankshaft 6 is a crank pin 8 which is eccentrically positioned with respect to the axis of the crankshaft 6, and which is rotatably positioned within a central axial bore in the piston 3 in a bushing 9 fitted within the said central axial bore of the piston. Extending in opposite directions from the said axial central bore of the piston are circular apertures 10, which may be somewhat larger in diameter than the said axial central bore and which open against the end walls- 2 Extending axially through the crankshaft 6 is a longitudinal bore 11 which is connected with a source of rotary piston cooling oil (not shown) by conventional means, and

branch holes

12 and 13 connect the longitudinal bore 11 with apertures 10 within the piston 3 to supply the cooling oil for apertures 10. Fixed in one circular aperture 10 is an internal gear 14 which meshes with an external gear 15 fixed on the crankshaft bushing 7.

Surrounding apertures 10 on each end face of the piston 3 are circular grooves 16 within which sealing rings 17 are inserted. Sealing rings 17 are axially slidable within but are fixed against rotation with, respect to the circular grooves 16. Behind the sealing rings 17 within the grooves 16 are circular recesses 19 within which are positioned circular springs 18 urging the sealing rings 17 outwardly against the internal faces of the

end walls

2 and 2. Between ther adially inwardly facing wall of the grooves 16 and the radially outwardly facing surfaces of the sealing rings 17 are circular passages 29 through which the recesses 19 behind the sealing rings are in communication with the combustion chamber a when the outer sealing members 5 permit the combustion gas to leak past the sealing members 5. In the radially outwardly facing surface of the groove is a circular groove 21 within which is an auxiliary sealing ring 22 in tight sealing engagement between the radially inwardly facing surface of the sealing ring 17 and the bottom of the groove 21. Numeral 23 designates drain ports in the

end walls

2 and 2 to exhaust cooling oil from the aperture 10.

The engine is operated in the conventional manner by firing the compressed gas compressed within the chamber a by rotation of the triangular piston 3. Intake of combustible gas and exhausting of the products of combustion is carried out by means of conventional intake and exhaust ports (not shown). Leakage of the compressed gas and products of combustion past the side sealing member 5 causes gas to flow along the gap between the end face of the rotary piston 3 and end walls 2 and 2' and into the circular passages 20', and thus into the circular recesses 19. The pressure of the gas which has thus leaked past the sealing member 5 and reached the recess 19 forces the sealing rings 17 against the internal face of the

end walls

2 and 2, and increases the sealing effect between the rotary piston and the end walls in proportion to the pressure of the thus leaked gas. Accordingly the sealing rings 17 automatically adjust the sealing effect in proportion to the pressure of the leaking gas which is applied thereto. And because the leaked gas is led along the passage 20 into the recess 19, concentrated action of the pressure against the contact area between the sealing ring and the end wall, which-causes deterioration of the sealing effect, is avoided.

During the operation of the engine, cooling of the rotary piston is carried out by supplying cooling oil to the space within the apertures provided in the rotary piston, from a source of cooling oil (not shown) through the longitudinal bore 11 and the

branch holes

12 and 13 in the crankshaft 6. Depending on the speed of rotation of the rotary piston, the cooling oil supplied to the apertures 10 is affected by the centrifugal force, due to the revolution of the piston 3, and is forced radially against the circular wall of the apertures 10. This causes, during the operation of the engine, leaking of the cooling oil past the sealing rings 17. According to the present invention, the sealing effect between the sealing rings 17 and the end Walls of the casing is increased in proportion to the pressure of the gas leaking from the combustion chamber a, and the auxiliary sealing ring 22 maintains a tight seal between the radially outwardly facing wall of the grooves 16 and the radially inwardly facing surface of the sealing rings 17. Thus the leaking of the cooling oil past the sealing ring 17 from the apertures 19 is also entirely prevented.

The springs 18 behind the rings 17 act to compensate the positioning of the rings 17 when wear occurs at the contact face between the rings 17 and the end walls 2 and 2'.

FIG. 5 shows a modified form of sealing ring 17a which is similar to the sealing ring 17 of FIGS. 1-4 in that it is similarly mounted in a circular groove 16 in the end face of a rotary piston 3 such that a space 20 is left between the radially outwardly facing face of the sealing ring 17a and the radially inwardly facing surface of the groove 16 and a recess 19 is left behind the sealing ring. However, it differs from the sealing ring 17 in that a projecting circular lip 24 is provided on the face of the sealing ring opposed to the internal face of the end walls 2 and 2' which wipes the oil leaking along the inner face of the end wall off said face of the end wall. In addition, instead of having a circular groove 21 in the radially outwardly facing surface of the groove 16, a circular groove 21;; is provided in the radially inwardly facing surface of the sealing ring 17a in which is positioned an auxiliary sealing ring 22 identical to the sealing ring 22 of the embodiments of FlGS. l-4, and which functions in the same way. The function of the embodiment of FlG. 5 is the same as that of FIGS, 1-4.

FIGS. 6 and 7 show a modified form of the invention in which structure of the casing, rotor, etc., are the same as in the embodiment of FIGS. 14, but in which the sealing ring is modified so that the circular passages 29 are provided between the radially outwardly facing wall of the grooves 16 and the radially inwardly facing surface of the sealing rings 171 so that the circular recesses 19 are in communication with the apertures 10. The cooling oil under the effect of centrifugal force, which is due to the rotation of the piston 3, is led along the passages 20 and received within the recesses 1?, and the sealing rings 17]) are forced outwardly against the inner face of the end walls by the pressure of the cooling oil, and increase the sealing effect in proportion to the amount of centrifugal force. The auxiliary sealing rings 22b in this modified form are positioned within circular grooves 21b provided on the radially outwardly facing circumferential surf-ace of the sealing rings 17b and maintain a tight seal between the sealing rings 17b and the radially inwardly facing circular wall of the grooves 16. The groove and auxiliary sealing ring can also be provided in the radially inwardly facing wall of the groove 16.

FIGS. 8, 9, 10 and 11 show a further modified form of the invention, in which the piston 3 in a motor the same as that shown in FIGS. 1 and 2 has, in addition to the inner circular grooves 16 which surround the apertures 1t} and which are provided on both end faces of the piston 3, additional outer circular grooves 16 which are positioned radially outwardly of grooves 16 surround the grooves 16. The sealing ring is provided in the radially inwardly positioned groove and is ar ranged in a manner similar to the embodiment of FIGS. 6 and 7 so that a circular passage 20 is left between radially outwardly facing wall of the grooves 16 and the radially inwardly facing surface of the sealing rings 17c, and the sealing ring 17c is provided in the outer groove and is arranged in a manner similar to embodiment of FIGS. 3 and 4 so that a passage 2% is left between the radially inwardly facing wall of the groove 16 and the radially outwardly facing surface of the sealing ring 17c. Thus the recesses 19 behind the sealing rings 170 are connected with the apertures 10 in the piston 3, and the recesses 19 behind the sealing rings 170 are connected with the combustion chamber a through the gap between the outer sealing members 5 and the inner surface of

walls

2 and 2 during operation of the engine. During the operation of this modified embodi ment, the cooling oil under the effect of centrifugal force is led along the circular passages 21) from the apertures 10 in the piston 3 and into the recesses 19, and at the same time the gas leaking from the combustion chamber past the outer sealing member 5 is led along the circular passages 20 and into the recesses 19, and the sealing effect of sealing

rings

17c and 170 is increased with the increasing pressure applied thereto as the speed of the engine increases. If the cooling oil should leak past the rings 17c, it will be blocked by the outer sealing rings 17c, and if the gas from the chamber a should leak past the outer sealing ring 17c, it will be blocked by the inner sealing ring 17c, so that the seal between the piston and the end walls is complete. The auxiliary seal rings 22 are positioned within the grooves 21c provided on the radially outwardly facing circumferential face of the inner sealing rings 17c and effect sealing between the inner sealing rings 17c and the radially inwardly facing circular wall of the grooves 16 similar to the embodiment of FIG. 6. Additional auxiliary sealing rings 22 are positioned within the grooves 210' provided on the radially inwardly facing circumferential face of the outer sealing rings 17c and likewise effect sealing between the outer sealing ring 170' and the radially outwardly facing circular wall of the grooves 16. The sealing rings 17c and 170 are maintained in contact with the inner face of the end walls by means of springs 18 and 18' installed behind the sealing rings.

FIG. 12 shows a modified form of the sealing rings 17d and 17d which are each provided with a projecting

circular lip

24d and 24d respectively at the point Where they contact the inner face of the end wall, whereby the oil leaking along the inner face of the end walls is scraped off by the projecting

lips

24d and 24d. FIGS. 13 and 14 also show a modified form of the sealing unit similar to the embodiment of FIG. 4 and in which the auxiliary seal rings 22 and 22' are installed within circular grooves 212 and 21e' which are provided in the walls of the grooves 16 and 16' and form a seal between the wall of the grooves and the sealing rings.

What is claimed is:

1. A rotary piston and sealing means for a rotary piston internal combustion engine having an annular casing with a trochoidal shaped internal peripheral wall and a crankshaft within said casing for eccentrically rotating a rotary piston Within the casing, and the crankshaft having cooling oil bores therethrough for supplying cooling oil to a rotary piston, and the casing having end walls on the ends thereof with substantially flat internal faces, said rotary piston and sealing means comprising a triangular shaped rotary piston having substantially flat end faces adapted to be eccentrically mounted on the crankshaft for rotation within the annular casing, sealing means at the apexes of said rotary piston and along the outer edges of the piston end faces adapted to seal against the internal peripheral wall of the annular casing and the flat internal face-s of the end walls for sealing off the combustion chambers and compressing chambers from the space between the end faces of the piston and the end walls, said piston having annular chambers around the crankshaft and opening out of each of the end faces of the piston and adapted to receive cooling oil from the bores in the crankshaft, and said piston having two circular grooves in each end face intermediate the annular oil chamber and the sealing means, said grooves each being defined by opposed radially facing surfaces and a laterally facing bottom surface, a sealing ring in each said circular groove, the sealing ring in the outermost circular groove being in sealing engagement with the outwardly radially facing surface of said groove and being spaced from the inwardly radially facing surface and bottom surface of said outermost groove, and the sealing ring in the innermost circular groove being in sealing engagement with the inwardly radially facing surface of said groove and being spaced from the outwardly radially facing surface and bottom surface of said innermost groove, and spring means in each of the spaces between the circular sealing rings and the bottom surfaces of said grooves and urging said rings out of said grooves against the internal face of the end wall adjacent the end face of the piston.

2. A rotary piston and sealing means as claimed in claim 1 in which there is an auxiliary groove in one of the radially facing surfaces of each of the sealing rings and grooves which are in sealing engagement, and an auxiliary sealing ring in each auxiliary groove for providing the sealing engagement between the groove face and the sealing ring face.

3. A rotary piston and sealing means as claimed in claim 2 in which the auxiliary grooves are in the sealing r1ngs.

4. A rotary piston and sealing means as claimed in claim 2 in which the auxiliary grooves are in the radially facing surfaces of the grooves.

5. A rotary piston and sealing means as claimed in claim 1 in which each sealing ring has a projection on the face thereof opposed to the internal face of the end wall for engagement With the end wall.

6. A rotary piston and oil sealing means for a rotary piston internal combustion engine having an annular casing with a tro'choidal shaped internal peripheral wall; a crankshaft rotatably supported within said casing and having a crank pin portion located in the said casing; said crankshaft having cooling oil bores therethrough for supplying cooling oil to a rotary piston; a triangular rotary piston having substantially fiat end faces and eccentrically rotatably journaled on the said crank pin portion; sealing means at the apexes of said rotary piston and along the outer edges of the piston end faces sealingly defining working chambers between the casing and the rotary piston; and said rotary piston having annular chambers around the crankshaft and opening out of each of the end faces of the piston and into which said oil bores open to receive cooling oil from said bores; said rotary piston and oil seal means comprising at least one circular groove in each end face of the rotary piston intermediate the annular cooling oil chamber and the sealing means; each circular groove being defined by spaced opposed radial/1y facing surfaces which are parallel and coaxial and a laterally facing bottom surface; a wear-resistant and substantially rectangular cross-section metal oil seal ring axially slidably inserted within each of the said circular grooves; a wave spring means disposed in the space between each sealing ring and the bottom face of the groove so that the said sealing ring is urged axially out of the groove and resiliently and sealingly engaged with the internal face of the end wall; and said sealing ring being in sealing engagement with the radially inwardly facing surface of said circular groove and spaced from the radially outwardly facing surface of said groove and from the bottom surface of the groove, whereby cooling oil under pressure can pass between the sealing ring and the radially outwardly facing surface of said circular groove and act on the sealing ring in combination with the said wave spring to urge it against the inner face of the end wall so that the sealing effect is increased responsive to the oil pressure applied thereto; one of the radially facing surfaces of the sealing ring and theg roove which are in sealing engagement having an auxiliary annular groove therein; and an auxiliary sealing ring in each auxiliary annular groove for assuring sealing engagement of the radially inwardly facing surface of the circular groove with the sealing ring.

7. A rotary piston and oil sealing means as claimed in claim 6 in which the auxiliary annular groove is in the radially outwardly facing surface of the sealing ring.

8. A rotary piston and oil sealing means as claimed in claim 6 in which the auxiiiary annular groove is in the radially inwardly facing surface of the groove.

9. A rotary piston and oil sealing means as claimed in claim 6 in which the sealing ring has a projection on the face thereof opposed to the internal face of the end wall for engagement wit-h the end wall.

References Cited by the Examiner UNITED STATES PATENTS 3,134,600 5/1964 Fisch 1238 3,165,259 1/1965 Muller et al 1238 3,171,590 3/1965 Bente le et al 123-8 3,179,331 4/1965 Paschke et a1. t230- 3,180,563 4/1965 Jones et a1 23O145 FOREIGN PATENTS 939,189 10/1963 Great Britain.

DONLEY J. STOCKING, Primary Exa miner.

WILBUR J. GOODLIN, Examiner.

Claims

1. A ROTARY PISTON AND SEALING MEANS FOR A ROTARY PISTON INTERNAL COMBUSTION ENGINE HAVING AN ANNULAR CASING WITH A TROCHOIDAL SHAPED INTERNAL PERIPHERAL WALL AND A CRANKSHAFT WITHIN SAID CASING FOR ECCENTRICALLY ROTATING A ROTARY PISTON WITHIN THE CASING, AND THE CRANKSHAFT HAVING COOLING OIL BORES THERETHROUGH FOR SUPPLYING COOLING OIL TO A ROTARY PISTON, AND THE CASING HAVING END WALLS ON THE ENDS THEREOF WITH SUBSTANTIALLY FLAT INTERNAL FACES, SAID ROTARY PISTON AND SEALING MEANS COMPRISING A TRIANGULAR SHAPED ROTARY PISTON HAVING SUBSTANTIALLY FLAT END FACES ADAPTED TO BE ECCENTRICALLY MOUNTED ON THE CRANKSHAFT FOR ROTATION WITHIN THE ANNULAR CASING, SEALING MEANS AT THE APEXES OF SAID ROTARY PISTON AND ALONG THE OUTER EDGES OF THE PISTON END FACES ADAPTED TO SEAL AGAINST THE INTERNAL PERIPHERAL WALL OF THE ANNULAR CASING AND THE FLAT INTERNAL FACES OF THE END WALLS FOR SEALING OFF THE COMBUSTION CHAMBERS AND COMPRESSING CHAMBERS FROM THE SPACE BETWEEN THE END FACES OF THE PISTON AND THE END WALLS, SAID PISTON HAVING ANNULAR CHAMBERS AROUND THE CRANKSHAFT AND OPENING OUT OF EACH OF THE END FACES OF THE PISTON AND ADAPTED TO RECEIVE COOLING OIL FROM THE BORES IN THE CRANKSHAFT, AND SAID PISTON HAVING TWO CIRCULAR GROOVES IN END FACE INTERMEDIATE THE ANNULAR OIL CHAMBER AND THE SEALING MEANS, SAID GROOVES EACH BEING DEFINED BY OPPOSED RADIALLY FACING SURFACES AND LATERALLY FACING BOTTOM SURFACE, A SEALING RING IN EACH SAID CIRCULAR GROOVE, THE SEALING RING IN THE OUTERMOST CIRCULAR GROOVE BEING IN SEALING ENGAGEMENT WITH THE OUTWARDLY RADIALLY FACING SURFACE OF SAID GROOVE AND BEING SPACED FROM THE INWARDLY RADIALLY FACING SURFACE AND BOTTOM SURFACE OF SAID OUTERMOST GROOVE, AND THE SEALING RING IN THE INNERMOST CIRCULAR GROOVE BEING IN SEALING ENGAGEMENT WITH THE INWARDLY RADIALLY FACING SURFACE OF SAID GROOVE AND BEING SPACED FROM THE OUTWARDLY RADIALLY FACING SURFACE AND BOTTOM SURFACE OF SAID INNERMOST GROOVE, AND SPRING MEANS IN EACH OF THE SPACES BETWEEN THE CIRCULAR SEALING RINGS AND THE BOTTOM SURFACES OF SAID GROOVES AND URGING SAID RINGS OUT OF SAID GROOVES AGAINST THE INTERNAL FACE OF THE END WALL ADJACENT THE END FACE OF THE PISTON.