Apex seal arrangement for rotary internal combustion engine

1. A rotor for a Wankel engine comprising:

a body having two axially spaced apart end faces, and a peripheral face extending between the two axially spaced apart end faces and defining three circumferentially spaced apex portions, each of the three circumferentially spaced apex portions having two circumferentially spaced apart grooves extending radially inwardly into the rotor body, each of the two circumferentially spaced apart grooves extending between the two axially spaced apart end faces;

the rotor includes two axially spaced apart end plates each in contact with the peripheral face and extending radially adjacent a respective one of the two axially spaced apart end faces, each of the two axially spaced apart end faces having two slots defined therethrough in alignment with the two the two axially spaced apart end faces grooves; and

two circumferentially spaced apart apex seals at each of the apex portions, said each of the two circumferentially spaced apart apex seals being received in a respective one of the two circumferentially spaced apart grooves, protruding radially from the peripheral face of the body and protruding axially from the two axially spaced apart end faces, and

at least a portion thereof received in the corresponding slot of a respective one of the end plates; and

a spring positioned in said each of the two circumferentially spaced apart apex seals;

wherein the spring further includes:

a respective first biasing member biasing the apex seal radially outwardly away from the peripheral face of the body; and

a respective second biasing member biasing the apex seal axially outwardly away from a respective one of the two axially spaced apart end faces and extending between radial surfaces of the apex seal and of a respective one of the end plates;

wherein the two circumferentially spaced apart apex seals of a same one of the three circumferentially spaced apex portions are biased by the respective second biasing member in opposite axial directions from one another.

2. A rotor for a Wankel engine comprising:

a body having two axially spaced apart end faces, and a peripheral face extending between the two axially spaced apart end faces and defining three circumferentially spaced apex portions, each of the three circumferentially spaced apex portions having two circumferentially spaced apart grooves extending radially inwardly into the rotor body, each of the two circumferentially spaced apart grooves extending between the two axially spaced apart end faces; and

two circumferentially spaced apart apex seals at each of the apex portions, said each of the two circumferentially spaced apart apex seals being received in a respective one of the two circumferentially spaced apart grooves, protruding radially from the peripheral face of the body and protruding axially from the two axially spaced apart end faces, and

a spring positioned in said each of the two circumferentially spaced apart apex seals;

wherein the spring further includes:

a respective first biasing member being a radial action portion which is in contact with a first surface of the apex seal and pushing the apex seal radially outwardly away from the peripheral face of the body; and

a respective second biasing member being an axial action portion which is in contact with a second surface of the apex seal and pushing the apex seal axially outwardly away from a respective one of the end faces;

wherein the respective first biasing member being a radial action portion is distinct from the second biasing member being an axial action portion of the spring; and

wherein the two apex seals of said each of the apex portions are biased by the respective second biasing member being an axial action portion which is in opposite axial directions from one another.

3. The rotor as defined in claim 2 , wherein at said each of the apex portions:

the rotor further includes two axially spaced apart end plates;

wherein each of the two axially spaced apart end plates is in contact with the peripheral face and is extending radially adjacent a respective one of the end faces;

wherein said each of the two axially spaced apart end plates has two slots defined therethrough in alignment with the two circumferentially spaced apart grooves; and

each of the two apex seals has opposed ends;

wherein said each of the two apex seals has at least a portion thereof received in the corresponding slot of said each of the two axially spaced apart end plates respectively;

the second biasing member being a axial action portion of the spring for said each of the two apex seals extending between radial surfaces of said each of the two apex seals and of said each of the two axially spaced apart end plates respectively.

4. The rotor as defined in claim 3 ,

wherein said each of the two apex seals includes an indentation in an end thereof adjacent said each of the two axially spaced apart end plates;

wherein the indentation defines a radially extending surface and an axially protruding finger located radially outwardly from the radially extending surface,

wherein the second biasing member being a axial action portion of the spring extends between the radially extending surface and said each of the two axially spaced apart of the end plates respectively; and

wherein the axially protruding finger is received in the slot of said each of the two axially spaced apart of the end plates respectively.

5. The rotor as defined in claim 2 , wherein the two axially spaced apart end faces include first and second end faces, the rotor including first face seals protruding from the first axially spaced apart end face and second face seals protruding from the second axially spaced apart end face, the first and second face seals being biased axially outwardly away from the first axially spaced apart end face and second axially spaced apart end face, respectively, with one of the first face seals and one of the second face seals extending from said each of the three circumferentially spaced apex portions;

said each of the two apex seals biased radially outwardly away from the first end face extending between curled ends of two adjacent ones of the first face seals and being in direct contact therewith, said each of the two apex seals biased radially outwardly away from the second end face extending between curled ends of two adjacent ones of the second face seals and being in direct contact therewith.

6. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart two-apex seals is made of ceramic.

7. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart apex seals is monolithic.

8. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart apex seals has a substantially rectangular shape.

9. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart apex seals is made of ceramic.

10. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart apex seals is monolithic.

11. The rotor as defined in claim 2 , wherein said each of the two circumferentially spaced apart apex seals has a substantially rectangular shape.

12. A rotary internal combustion engine comprising:

a stator body having an internal cavity defined by two axially spaced apart end walls and a peripheral wall extending between the end walls;

wherein the cavity has an epitrochoid shape defining two lobes; and

wherein the peripheral wall has at least an inlet for supplying air and for injecting fuel, an outlet for discharging exhaust gas, and an ignitor;

a rotor body having two axially spaced apart end faces each extending in proximity of a respective one of the end walls of the stator body, and a peripheral face extending between the two axially spaced apart end faces and defining three circumferentially spaced apex portions, the rotor body being engaged to an eccentric shaft to rotate within the cavity with each of the three circumferentially spaced apex portions remaining adjacent the peripheral wall; and

a spring including a first respective spring member and a second respective spring member;

wherein said each of the three circumferentially spaced apex portions includes a first circumferentially spaced apart apex seal and a second circumferentially spaced apart apex seal protruding radially from the peripheral face of the rotor body and each protruding axially from both the two axially spaced apart end faces;

wherein each of the first circumferentially spaced apart apex seal and the second circumferentially spaced apart apex seal has a respective first surface and being radially biased against the peripheral wall by the respective first spring member in contact with the respective first surface;

wherein the first circumferentially spaced apart apex seal is axially biased against a first one of the end walls;

wherein the second circumferentially spaced apart apex seal is axially biased against a second one of the end walls;

wherein the first circumferentially spaced apart apex seal and the second circumferentially spaced apart apex seal are axially biased independently from one another; and

wherein said each of the first circumferentially spaced apart apex seal and the second circumferentially spaced apart apex seal has a respective second surface and is axially biased by the respective second spring member in contact with the respective second surface.

13. The engine as defined in claim 12 ,

wherein said each of the three circumferentially spaced apex portions of the rotor body further includes

a first end plate abutting the peripheral face and extending radially adjacent the first end wall and having two slots defined therethrough; and

a second end plate abutting the peripheral face and extending radially adjacent the second end wall and having two slots defined therethrough;

wherein each of the two slots of the first end plate and the second end plate is aligned with a corresponding one of two axial grooves defined in the peripheral face receiving a respective one of the first circumferentially spaced apart apex seal and the second circumferentially spaced apart apex seal therein;

wherein the respective second spring member of the first circumferentially spaced apart apex seal extends between the second end plate and the second surface of the first circumferentially spaced apart apex seal; and

wherein the respective second spring member of the second circumferentially spaced apart apex seal extending between the first end plate and the second surface of the second circumferentially spaced apart apex seal.

14. The engine as defined in claim 12 ,

wherein the rotor includes first face seals protruding from one of the two axially spaced apart end faces and second face seals protruding from the other of the two axially spaced apart end faces, the first and second face seals being biased against the first and second end wall, respectively, with one of the first face seals and one of the second face seals extending from said each of the three circumferentially spaced apex portions;

wherein the first circumferentially spaced apart apex seal extends between curled ends of two adjacent ones of the first face seals and is in direct contact therewith; and

wherein the second circumferentially spaced apart apex seal extends between curled ends of two adjacent ones of the second face seals and is in direct contact therewith.

15. The engine as defined in claim 12 , wherein the respective first and second spring members of the spring positioned in said each of the first circumferentially spaced apart apex seal and the second circumferentially spaced apart apex seal have different sections.

16. A method of sealing chambers of a Wankel engine between apex portions of a rotor of the engine, a peripheral wall of a rotor cavity of a body of the engine having at least an inlet for supplying air and for injecting fuel, an outlet for discharging exhaust gas, an ignitor, and an eccentric shaft being engaged to the rotor to rotate within the rotor cavity with three circumferentially spaced apex portions remaining adjacent the peripheral wall, the method comprising:

during an engine operation,

limiting fluid communication across the peripheral wall by radially pushing first and second circumferentially spaced apart apex seals extending from the rotor against the peripheral wall with a respective radial spring member of a spring contacting a respective first surface of each of the first and second apex seals;

limiting fluid communication at a junction between the peripheral wall and a first one of two axially spaced apart end walls of the cavity by contacting one end of the first apex seal with the first end wall and axially pushing the first apex seal against the first end wall with a first axial spring member of the spring contacting a second surface of the first apex seal, and locating one end of the second apex seal in proximity of the first end wall; and

limiting fluid communication at a junction between the peripheral wall and a second one of the two axially spaced apart end walls of the cavity by contacting another end of the second apex seal with the second end wall and axially pushing the second apex seal independently from the first apex seal against the second end wall with a second axial spring member of the spring contacting a second surface of the second apex seal, and locating another end of the first apex seal in proximity of the second end wall.

17. The method as defined in claim 16 , wherein limiting the fluid communication at the junction between the peripheral wall and the first end wall further includes, at said each of the apex portions, axially pushing two first face seals extending from a first end face of the rotor on opposite sides of the first apex seal against the first end wall and abutting a curled end of each of the first face seals with the first apex seal, and limiting the fluid communication at the junction between the peripheral wall and the second end wall further includes, at said each of the apex portions, axially pushing two second face seals extending from a second end face of the rotor on opposite sides of the second apex seal against the second end wall and abutting a curled end of each of the second face seals with the second apex seal.

18. The method as defined in claim 16 , wherein radially pushing and axially pushing the first apex seal are simultaneously performed with the respective radial spring member of the spring at the first apex seal and the first axial spring member of the spring defining distinct sections of a same first spring, and radially pushing and axially pushing the second apex seal are performed simultaneously with the respective radial spring member of the second apex seal and the second axial spring member defining distinct sections of a same second spring.