Patent Publication Number: US-3876346-A

Title: Rotary engine with sealing means

Description:
United States Patent 1 m1 3,876,346  
 Kokochak Apr. 8, 1975 [54] ROTARY ENGINE WITH SEALING MEANS 3,196.84; 7/1965 Paschke i. l /I23 743 2 2 [75] Inventor: David G. Kokochak, Royal Oak. is 33 kil d] g I g H Mich v 4 4 i 4 [73] Assignee: General Motors Corporation, Primary Examiner-C. J. Husar Detroit, Mich. Attorney, Agent, or Firm-Robert M. Sigler [22] Filed: Oct. 18, 1973 [2i] Appl. No: 407,615 [57] ABSTRACT In a rotary engine, a portion of the corner seal adjacent to the forward side of the apex seal in the direc- 418mm; gf fig gi tion of rotor rotation is cut away to allow the flow of Fie&#39;ld 124 gases under pressure from the adjacent working cham.  
 her to the groove beneath the apex seal to assist the apex seal spring in biasing the apex seal outward and reduce the possibility of pop-back.&#34; A portion of the [56] References cued housing adjacent the corner seal may be cut away to UNITED STATES PATENTS further assist gas flow. 356.384 ll/l887 Verstruelc 418/267 unmso 5/I962 Benlclc 418/123 2 Clam, 5 Drawing figures T i-l== I a r ROTARY ENGINE WITI-I SEALING MEANS BACKGROUND OF THE INVENTION My invention relates to rotary engines. and particularly to means for sealing the working chambers of such engines. Such engines for generally have a rotor with a plurality of axially extending apexes, each apex having an axially extending groove therein. An apex seal member extending the axial length of the rotor is placed in each groove over a spring which biases it outward from the groove against the engine peripheral wall. These apex seal members projecting from the rotor against the peripheral wall isolate the engines working chambers from each other.  
  The pressure of gases in the working chamber, however, sometimes becomes so great that they seep through between the apex seal member and the periph eral wall into an adjacent working chamber in the phenomenon known as pop-back. If the spring means is increased in strength to reduce or eliminate this problem, the wear of the apex seal member against the peripheral wall can be accelerated to an unacceptable degree. However, an elimination of pop-back is desirable to improve the efficiency of rotary engines.  
  One method of reducing or eliminating pop-back is to provide means for the flow of gases under pressure into the groove underneath the apex seal member. The pressure of these gases exerts a force on an apex seal member which aids the spring bias. However, this force varies with gas pressure so that it is large only when a large force is needed and thus does not shorten apex sea] life as much as would a stronger apex seal spring.  
 A number of means have been suggested for providing the pressure gas passage. but these have involved problems of their own. Some have suggested providing pas sages through the rotor but these would involve expensive tooling operations. Others have suggested cutting away portions of the apex seal member. but this method results in continually decreasing resistance to gas flow under the apex seal member as the apex seal member wears with consequent accelerating wear.  
 SUMMARY OF THE INVENTION My invention provides for flow of pressure gases beneath the apex seal member by cutting away a portion of the corner seal member. A corner seal member modified according to my invention can be easily substituted for a convention] rotary engine corner seal member and, in operation, will not greatly change its resistance to gas flow therethrough since it does not wear as quickly as the apex seal member. In some cases my invention will require no changes to the rotor itself. Further details and advantages of my invention will be apparent from the following drawings and description of a preferred embodiment.  
 SUMMARY OF THE DRAWINGS FIG. 1 is a cutaway view ofa portion of an engine according to my invention.  
 FIG. 2 is a section view along line 2-2 in FIG. 1.  
 FIG. 3 is a section view along line 33 in FIG. 1.  
 FIG. 4 is a section view along line 44 in FIG. 2.  
  FIG. 5 shows a corner seal for use in the engine shown in FIGS. l4.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a rotary engine has a housing 10 forming an epitrochoidal peripheral wall 12 between a pair of parallel side walls, one of which is shown at 14. A rotor 16 is rotatably disposed within the housing 10. The rotor 16 has a plurality of apexes, one of which is shown at 18. The rotor 16 rotates eccentrically within the housing 10 in the direction indicated in FIG. 1 in a manner well known and described in the prior art. The rotor 16 forms a plurality of chambers 20. one between each pair of adjacent apexes 18, the volumes of which chambers 20 continuously change during rotor rotation.  
  The chambers 20 are sealed to hold gases under pressure by a plurality of seals carried by the rotor 16. A cylindrical plug is removed from each side of the rotor 16 near each apex 18&#39;, and a cylindrical corner seal 22 is inserted therein. The corner seal 22 is biased outward by a corner seal spring 24, a portion of which is shown in FIG. 2, into sealing engagement with the side wall 14.  
  An axially extending groove 26 is formed at each apex 18 in the rotor 16 and carried through as a groove 27 in each corner seal 22. An apex seal member 28 in each groove 26 is biased radially outward by an apex seal spring 30, a portion of which is shown in FIG. 2, into engagement with the peripheral wall 12. The apex seal member 28 and corner seal members 22. along with other seal members not shown, create seals between the rotor 16 and the peripheral wall l2 and side walls 14 to retain gases under varying pressures within the chambers 20 during engine operation.  
  In FIGS. 1 and 4, the spaces between the apex seal member 28 and the side walls of the grooves 26 and 27 are greatly exaggerated for purposes of illustration and explanation. The fit of apex seal member 28 in grooves 26 and 27 is actually quite snug, although not so tight as to not be slidable therein. In prior art devices only a comparatively small flow of gases occurs between the apex seal members 28 and the side wall of the groove 26 to the area underneath the apex seal member 28.  
  A corner seal 22 of my invention is shown in detail in FIG. 5. A portion of the groove 27 adjacent the inner axial end 32 on the forward side of the corner seal in the direction of rotor rotation is cut away to form a corner seal space 34. As seen in FIG. 4, the corner seal space 34 provides a wider conduit between the corner seal 22 and the apex seal member 28 to increase the flow of gases under pressure from the chamber 20 to the area of the groove 26 beneath the apex seal member 28. The pressure of gases underneath, and consequently the force on, the apex seal member 28 will thus vary with the pressure of the gases in chamber 20 attempting to push between the apex seal member 28 and the peripheral wall 12. As the pressure of the gases increases, so will force on the apex seal member 28, and vice versa.  
  Of course, whenever one of the chambers 20 has an increase in gas pressure therein there are actually two apex seal members that are affected. So far it has been shown how gases are admitted under the apex seal member 28 trailing the chamber 20 in the direction of rotor rotation. However, the same gas under pressure is retained under the apex seal member 28 for a portion of a rotor revolution to bias the apex seal member 28 leading the chamber in rotation. This occurs as a natural result of the operation of a rotary engine as described below,  
  It will be noted that, as the rotor 16 rotates, the apex seal member 28 on the trailing side of a chamber 20 that contains gases undergoing compression and detonation becomes the apex seal member on the leading side of the next chamber 20 to pass through this stage in the cycle. While the gases in the former chamber 20 were increasing in pressure, some of them flowed be tween the apex seal member 28 on its leading side and the adjacent side walls grooves 26 and 27 as described above. However, before all these gases can be ex hausted through this chamber 20 and the engine exhaust port, the building gas pressure in the following chamber 20 causes the apex seal member 28 to bear against the leading side wall of the groove 26 and temporarily prevent or reduce the escape of gases from under the apex seal member 28 into the chamber 20 now decreasing in pressure. The building gas pressure in the trailing chamber 20 prevents their escape in that direction, so they remain under the apex seal member 28 to bias it outward against peripheral wall 12 during the pressure peak of the following chamber 20 and escape only after the threat of pop back is over.  
  If, in the design of a particular rotary engine, it is found that more gas flow is required into the groove beneath the apex seal member 28 than can be 34 with the corner seal space 34 alone, a portion of the rotor radially outward from the corner seal space 4 can be re moved to form a rotor space 36, shown in FIG, 4, in communication with the corner seal space 34. This will have the effect of shortening the distance D that gases must flow in the narrow space between the apex seal member 28 and the wall of the groove 26 and thus of reducing resistance to flow through this space.  
  The rotary engine described above is more efficient than one which allows its compressed gases to popback over the apex seals; but it accomplishes this improvement in efficiency without greatly shortening apex seal life or greatly changing its characteristics as the apex seals wear.  
  The embodiment shown and described is for pur poses of disclosure and illustration only, and should not be considered as limiting my invention, since different but equivalent structures will occur to those skilled in the art.  
 i claim:  
 I. A rotary engine comprising, in combination: a  
 housing having an internal peripheral wall and a pair of internal end walls; a rotor in said housing for rotation about an axis extending between said end walls, said rotor having a pair of side walls adjacent said housing end walls and a plurality of axially extending apex portions, said rotor forming with said housing a plurality of working chambers, each apex portion having formed therein an axial groove, each apex portion further having formed therein on at least one axial end thereof a cylindrical bore, said cylindrical bore extending into said rotor from one of said side walls and being open to said groove, said cylindrical bore further being spaced from the radially outer surface of said rotor; an apex sealing member in each of said grooves; apex spring means in each of said grooves to bias said apex sealing member outward against said internal peripheral wall; a cylindrical corner seal in each cylindrical bore, each said cylindrical corner seal having a groove formed therein for continuing said axial groove there through and receiving an end of said apex sealing member therein, a portion of said corner seal groove adjacent the axially inner end of said cylindrical corner seal being wider to the forward side in the direction of rotor rotation than the remainder of said groove to form a corner seal space between said corner seal groove wall and said apex seal member, whereby the flow of pressure gases from the working chamber between said apex seal member, rotor and corner seal groove wall into said groove radially beneath said apex seal member to assist said apex spring means in biasing said apex seal member against said peripheral wall is increased.  
  2. A rotary engine comprising, in combination: a housing having an internal peripheral wall and a pair of internal end walls; a rotor in said housing for rotation about an axis extending between said end walls, said rotor having a pair of side walls adjacent said housing end walls and a plurality of axially extending apex portions, said rotor forming with said housing a plurality of working chambers, each apex portion having formed therein an axial groove, each apex portion further having formed therein on at least one axial end thereof a cylindrical bore, said cylindrical bore extending into said rotor from one of said side walls and being open to said groove, said cylindrical bore further being spaced from the radially outer surface of said rotor; an apex sealing member in each of said grooves; apex spring means in each of said grooves to bias said apex sealing member outward against said internal peripheral wall; a cylindrical corner seal in each cylindrical bore, each said cylindrical corner seal having a groove formed therein for continuing said axial groove therethrough and receiving an end of said apex sealing member therein, a portion of said corner seal groove adjacent the axially inner end of said cylindrical corner seal being wider to the forward side in the direction of rotor rotation than the remainder of said groove to form a corner seal space between said corner seal groove wall and said apex seal member, a portion of said rotor adjacent each corner seal space being cut away on the forward side of said rotor groove in the direction of rotor rotation to form a rotor space being open to said corner seal space, whereby pressure gases in the working chamber on the forward side of said rotor groove in the direction of rotor rotation may flow between said groove wall and said axial seal member, through said rotor space and through said corner seal space to said groove radially beneath said apex seal member to assist said apex spring means in biasing said apex seal member against said peripheral wall.