US3752607A

US3752607A - Rotary machine apex seal

Info

Publication number: US3752607A
Application number: US00232160A
Authority: US
Inventors: J Bilobran
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1972-03-06
Filing date: 1972-03-06
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14

Abstract

A rotary machine apex seal having passages for directing gas pressure to impinge upon the machine''s internal peripheral wall to provide a cushion of gas between the apex seal and this wall.

Description

United States Patent [191 UNlTED STATES PATENTS 3/1965 Schaller et a1. 418/ 124 X Bilobran Aug. 14, 1973 4] ROTARY MACHINE APEX SEAL 3,182,641 5/1965 Lamm 418/124 X [75] invent '9" Birmingham FOREIGN PATENTS OR APPLICATIONS [73] Assignee: General Motors Corporation, 1,247,094 8/1967 Germany 418/113 Detroit, Mich.

[22] Filed: Mar. 6, 1972 Primary Examiner-Carlton R. Croyle Assistant Examiner-Michae1 Koczo, Jr. [211 App! 232l60 Anomey-J. L. Carpenter et a1.

[52] U.S. Cl 418/124, 277/75, 418/113 I [51] Int. Cl. F01C 19/04 1 1 ABSTRACT [58] new of 2 A rotary machine apex seal having passages for directing gas pressure to impinge upon the machine 's internal [56] References Cited peripheral wall to provide a cushion of gas between the apex seal and this wall.

' 4 Claims, 7 Drawing Figures ROTARY MACHINE APEX SEAL This invention relates to a rotary machine apex seal and more particularly to a rotary machine apex seal running against a rotor housing on a gas cushion.

In rotary machines such as rotary combustion engines, pumps, compressors, and the like, wherein a seal arrangement'is provided at each rotor apex to continuously sealingly engage an internal peripheral wall to separate the machines working chambers which rotate with the rotor, one of the major considerations is the minimization of the wear of these apex seals. There are 1 two primary approaches to this objective, one being the choice of peripheral wall and seal materials for compatibility and wear life and the other being in the area of apex seal design. Up to the present time, the choice of materials has been substantially limited by the sliding friction encountered in conventional seal designs.

The rotary machine apex seal according to the present invention provides for a wider than normal choice of materials by having a surface with a substantial area that is opposite and remains adjacent to the rotor housings internal peripheral wall without radial movement as the rotor rotates. A plurality of orifices extend through this surface and are connected to direct gas flow from at least one of the machines chambers on opposite sides of the seal to impinge upon the internal peripheral wall to provide a cushion of gas between the seal and this wall so that the seal runs on a gas cushion rather than have sliding contact with the wall.

An object of the present invention is to provide a new and improved rotary machine apex seal Another object is to provide in a rotary machine an apex seal that runs against a rotor housing on a cushion of gas derived from the machines chambers.

Another object is to provide in a rotary machine a rotor apex seal that has a passage for delivering gas from at least one of the chambers on opposite'sides of the seal to impinge upon the rotors internal peripheral wall to provide a cushion of gas between the seal and the internal peripheral wall as the rotor rotates.

Another object is to provide an apex seal for a rotary machine wherein chamber gas pressure is utilized to effect a gas cushion between each apex seal and the rotor housings internal peripheral wall to minimize apex seal wear.

become more apparent from the following description and accompanying drawing in which:

FIG. I is a transverse sectional view of a rotary machine having apex seals according to the present invention.

FIG. 2 is an enlarged perspective of one of the apex seals of FIG. 1.

FIG. 3 is an enlarged view taken along the line 33 in FIG. 2.

FIG. 4 is an enlarged partial perspective view of a modification of the apex seal of FIG. 1.

FIG. 5 is an enlarged partial perspective view of anothermodification of the apex seal of FIG. 1.

FIG. 6 is a view similar to FIG. 3 of another embodiment of the apex seal according to the present invention.

FIG. 7 is a perspective view of the apex seal of FIG. 6.

The apex seal according to the present invention is for use in rotary machines including rotary combustion engines, compressors, pumps, and the like. Referring to FIG. 1, the rotary machine may, for example, be an intemal combustion rotary engine of the Wankel type comprising a stationary outer body or housing 10 having a rotor cavity 12 that is defined by an inwardly facing internal peripheral wall 14 and a pair of axially spaced opposed end walls 16, only one of which is shown. In the Wankel engine the peripheral wall 14 is in the shape of a two-lobed epitrochoid or a curve parallel thereto. A rotor 18 having a general shape of a triangle with three intersecting peripheral faces 20 is mounted within the rotor cavity I2 on an eccentric 22 of a crankshaft 24 which is rotatably mounted outboard of the rotor cavity in the end walls 16 and aligned with the cavitys axis. Gearing, not shown, between the housing 10 and the rotor 18 enforces a fixed, cyclic relation between the rotor and the crankshaft and the rotor faces cooperate with the peripheral wall and end walls to define three variable volume combustion or working chambers 26. The chambers 26 are spaced around the rotor and move with the rotor within the housing as the rotor rotates about its axis while planetating with respect to the output axis to rotate the crankshaft 24. A fuel-air inlet passage 28 'whose opening and closing is effected by the rotor 18 provides for periodic admission of fuel-air mixture to each chamber 26, a spark plug30 provides for ignition of the fuel-air mixture and an exhaust passage 31 whose opening and closing is effected by the rotor 18 provides for exhaust of the products of combustion from each chamber as the rotor rotates in the direction indicated by the arrow in FIG. 1 with each chamber undergoing intake, comgine.

Sealing of the chambers 26 is effected by an apex seal 32 and a pair of comer seals 34 at each rotor apex and side seals 36 on each rotor side which extend between adjacent corner seals. At each rotor apex as shown in FIG. 2, the comer seals 34 which are cylindrical in shape are mounted in axially aligned circular apertures 38in opposite sides of the rotor. The side seals 36 are mounted in arcuate grooves in the two sides of the rotorand extend between and sealingly engage the corner seals 34, both the corner seals and the side seals being urged by suitable springs, not shown, to engage the rotor cavity's end walls 16. Each of the apex seal members 32 extends from one end wall to the other and is mounted in an axially extending radially outwardly facing groove 40 at the rotor apex with the corner seals 34 each having a slot 42 providing a continuation of the groove 40 to accommodate the apex seal 32 at its out board ends to effect a sealing link between the side seals and the respective apex seal. L i

In one embodiment of the apex seal according to the present invention shown in FIGS. 2 and 3 there is provided a manifold 44 in the seal member 32 formed by an axially extending groove in one side of the seal 32, this groove being closed at each apex seal end and continuously open to the chamber on this side of the seal which is the leading side as shown in FIG. 3 with the direction of rotor rotation indicated by the arrow. The seal member 32 has a surface 46 that is curved in crosssection and remains close over a substantial area to the internal peripheral wall 14 without radial seal movement as the rotor and crankshaft rotate. This may be effected, for example, as disclosed in Unites States patent to Wankel U.S. Pat. No. 2,988,008 wherein the inner peripheral wall 14 has the form of a curve outward of and parallel to a true epitrochoid and the apex seal surface 46 has a constant radius of curvature equal to the perpendicular distance between the true epitrochoid and the actual inner peripheral wall 14. With such an arrangement and assuming there is line contact between the apex seal surface 46 and the inner peripheral wall 14 such as is forced by a spring bias, this line contact would traverse a substantial portion of the width of the seal without radial seal movement on rotor rotation as compared with when the inner peripheral wall 14 is a true epitrochoid and there is only a single line contact as the rotor rotates. As best shown in FIG. 3, a plurality of orifices 48 are connected at their radially inner ends to the manifold 44 and extend radially outward through the surface 46 in the direction of the inner peripheral wall 14. These orifices 48 are spaced over both the width of the surface 46 as viewed in FIG. 3 and the length thereof as viewed in FIG. 2. The bottom of groove 40 is vented via slots 49 in the corner seals 34 and with the arrangement of manifold 44 the seal member 32 thus presents an effective differential pressure area to gas pressure to force the seal member radially inward.

During engine operation the gas pressure in the chamber 26 on the leading side of each seal member 32 during either compression or combustion is distributed by the manifold 44 to the orifices 48 which then direct the gas to impinge upon the peripheral wall 14. The orifices 48 are sized in relation to this gas pressure to provide a force opposing the centrifugal force on the apex seal which gas force acts to separate the apex seal from the rotor housing by a small distance such as several microns and effect a cushion or blanket of gasbetween the apex seal and the internal peripheral wall and a gas barrier between the adjacent chambers as the rotor rotates instead of sliding contact. Furthermore, with this arrangement of the manifold 44 being open to the chamber only on the leading side of the apex seal, any blowby of gas pressure is always directed toward the trailing side of this apex seal and thus to the trailing chamber. Thus, when the leading chamber is undergoing combustion, the products of this combustion are always directed toward the intake of the engine for recycling of the unburned hydrocarbons by the oncoming chamber which will subsequently undergo the combustion phase. Furthermore, with a small spacing now provided between the apex seal and the internal peripheral wall, the ability to direct lubrication to this area is enhanced, it being understood that lubrication of the apex seals is normally provided by adding oil to the fuel-air mixture.

In the FIG. 3 embodiment of the apex seal the gas cushion is effected by the gas jets from the orifice without subsequent gas flow direction control. To enforce the gas cushion, the apex seal gas distribution network may be modified as shown in FIG. 4 wherein portions similar to those shown in FIGS. l-3 are identified by the same numerals only primed and new portions are identified by new numbers. In the FIG. 4 modification of the apex seal 32' the orifices 48 from the manifold 44' are interconnected by a series of grooves 50 in the surface 46, these connections being such that each orifice 48 is linked by a groove 50 to each adjacent orifice and with the grooves arranged to be at an angle to the direction of apex seal movement. As a result, the gas is directed to impinge upon the inner peripheral wall 14 and then follows the grooves 50 to provide additional support to enforce the cushioning of the apex seal.

In FIG. 5 there is shown another modification to enforce the cushioning with portions of the apex seal similar to those shown in FIGS. 1-4 being identified by the same numerals only double primed. In the FIG. 5 modification there are again provided grooves 50" in the apex seal surface 46" which intersect with orifices 48" but unlike the groove connections in the FIG. 4 modification, the grooves 50" in the FIG. 5 modification also intersect each other in a grid pattern to further enhance distribution to enforce the gas cushion.

In the FIG. l-3 embodiments and the FIG. 4 and 5 modifications the pressure of the gas supplied to effect the gas cushion is from the leading chamber and thus is not always the highest gas pressure then available. To provide the highest available gas pressure to effect the gas cushion, the apex seal is constructed as shown in FIGS. 6 and 7 wherein positions similar to those shown in FIGS. 1-5 are identified by the same numerals only triple primed and new portions are identified by new numerals. In the FIG. 6 and 7 embodiment, the manifold 44" instead of being open on the leading side of the apex seal to the leading chamber is located radially inward of the rotor apex and extends through the seal member 32' from one side to the other. Then when the gas pressure is highest on the trailing side of the apex seal, this gas pressure forces the apex seal against the righthand wall of groove 40" as shown in FIG. 6 whereby the highest gas pressure is then transmitted by clearance 52 to the manifold 44" which then distributes it as before to the orifices 48'" Alternatively, when the gaspressure is highest on the leading side of the apex seal the apex seal 32' is urged against the left-handwall of the groove 40" and this higher gas pressure is then transmitted to manifold 44" through the clearance which is now on the leading side of the seal. Furthermore, it will be understood that there may be provided a series of grooves or a grid pattern as disclosed in the FIG. 4 and 5 modifications to enforce establishment of the gas cushion in the FIG. 6 embodiment. Thus, in the FIG. 6 and 7 embodiment, the flow of gas to the manifold is either from the compression side or the combustion side of the engine whichever gas pressure is the higher to maximize the establishment of the gas cushion for the apex seal.

The above described embodiments are illustrative of the invention which may be modified within the scope of the appended claims.

I claim:

1. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and saidcrankshaft rotate, gas passage means in said seal member for directing gas flow from at least one of the chambers on opposite sides of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and i said internal peripheral wall when said rotor and said crankshaft rotate. 1

2. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices extending through said seal member surface and a plurality of grooves in said seal member surface inter-' secting said orifices for directing gas flow from the chambers on the opposite sides of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wallwhen said rotor and said crankshaft rotate.

3. In a rotary machine, a housinghaving an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having pheripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said carnkshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall and having a leading side and a trailing side with respect to the direction of rotor rotation, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when :said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices connected through said leading side to the adjoining chamber and extending through said seal member surface for directing gas flow only from the chamber on the leading side of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.

4. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall. when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said intemal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall and having a leading side and a trailing side with respect to the direction of rotor rotation, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices extending through said seal member surface and communicating via said leading side of said groove with the leading adjoining chamber when this chamber has the highest gas pressure of the two adjacent chambers and alternately coinmunicating via said trailing side of said groove with the following adjoining chamber when this chamber has separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.

Claims

1. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member for directing gas flow from at least one of the chambers on opposite sides of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.

2. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a Rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices extending through said seal member surface and a plurality of grooves in said seal member surface intersecting said orifices for directing gas flow from the chambers on the opposite sides of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.

3. In a rotary machine, a housing having an internal peripheral wall and opposite internal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having pheripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said carnkshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall and having a leading side and a trailing side with respect to the direction of rotor rotation, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices connected through said leading side to the adjoining chamber and extending through said seal member surface for directing gas flow only from the chamber on the leading side of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.

4. In a rotary machine, a housing having an internal peripheral wall and opposite iNternal end walls cooperatively defining a rotor cavity, a crankshaft rotatably mounted in said housing, a rotor in said rotor cavity eccentrically rotatably mounted on said crankshaft, said rotor having a plurality of apex portions that remain adjacent said internal peripheral wall when said rotor and said crankshaft rotate, said rotor further having peripheral faces extending between adjacent pairs of said apex portions that cooperate with said cavity walls to define a plurality of chambers that vary in volume and move with said rotor as said rotor and said crankshaft rotate, and seal means mounted on each said apex portion of said rotor for continuously providing sealing between said internal peripheral wall and said rotor to sealingly separate adjacent pairs of said chambers as said rotor and said crankshaft rotate, each said seal means comprising an axially extending radially outwardly facing groove in the respective apex portion of said rotor, an elongated apex seal member in said groove radially movable outward toward said internal peripheral wall and having a leading side and a trailing side with respect to the direction of rotor rotation, said seal member at its radially outward end having a surface with a substantial area that is opposite and remains adjacent to said internal peripheral wall without radial seal member movement when said rotor and said crankshaft rotate, gas passage means in said seal member including a plurality of orifices extending through said seal member surface and communicating via said leading side of said groove with the leading adjoining chamber when this chamber has the highest gas pressure of the two adjacent chambers and alternately communicating via said trailing side of said groove with the following adjoining chamber when this chamber has the highest gas pressure of the two adjacent chambers for directing gas flow from the chamber on the leading side of said seal member to impinge upon said internal peripheral wall to provide a gas force opposing centrifugal force on said seal member which gas force acts to separate said seal member and said internal peripheral wall and effect a cushion of gas between said seal member and said internal peripheral wall when said rotor and said crankshaft rotate.