Two-stroke internal combustion engine

1. A two-stroke internal combustion engine comprising a cylinder and a cylinder head releasably secured thereto, the cylinder having a curvature, and a main exhaust port and at least one auxiliary exhaust port coverable at least in part by control slide members actuatable by a slide stem arranged at an angle to a cylinder axis and axially actuated by an actuator, wherein:

the control slide members are configured integrally with a common control slide, the common control slide being coupled to the slide stem; and

the slide stem passes through the cylinder head.

2. The two-stroke engine as set forth in claim 1 , wherein the control slide comprises:

a main member having a center of curvature whereby the main member is configured curved substantially corresponding to the curvature of the cylinder; and

auxiliary members configured integrally with the main member, and having substantially planar faces.

3. The two-stroke engine as set forth in claim 2 , wherein the control slide member has an upright axis, and the main member and auxiliary members have differing respective height dimensions relative to the upright axis.

4. The two-stroke engine as set forth in claim 2 , wherein the main member is between the auxiliary members and wherein each auxiliary member comprises:

a front face;

a rear face; and

a curved surface facing away from the main member and connecting the front face and the rear face, the surface having a center of curvature between the front face and the rear face.

5. The two-stroke engine as set forth in claim 3 , wherein the main member is between the auxiliary members and wherein each auxiliary member comprises:

a front face;

a rear face; and

a curved surface facing away from the main member and connecting the front face and the rear face, the surface having a center of curvature between the front face and the rear face.

6. The two-stroke engine as set forth in claim 2 , wherein an imaginary plane tangential to a front face of at least one auxiliary member located toward the main exhaust port intersects a second imaginary plane containing the center of curvature of the main member and a longitudinal centerline of the slide stem, the planes defining an angle in the range of approximately 55 degrees to approximately 90 degrees.

7. The two-stroke engine as set forth in claim 3 , wherein an imaginary plane tangential to a front face of at least one auxiliary member located toward the main exhaust port intersects a second imaginary plane containing the center of curvature of the main member and a longitudinal centerline of the slide stem, the imaginary planes defining an angle in the range of approximately 55 degrees to approximately 90 degrees.

8. The two-stroke engine as set forth in claim 4 , wherein an imaginary plane tangential to the front face of at least one auxiliary member located toward the main exhaust port intersects a second imaginary plane containing the center of curvature of the main member and a longitudinal centerline of the slide stem, the imaginary planes defining an angle in the range of approximately 55 degrees to approximately 90 degrees.

9. The two-stroke engine as set forth in claim 2 , wherein a longitudinal centerline of the cylinder and a longitudinal centerline of the slide stem intersect to define an angle in the range of approximately 10 degrees to approximately 45 degrees.

10. The two-stroke engine as set forth in claim 9 , wherein the longitudinal centerline of the cylinder and the longitudinal centerline of the slide stem intersect to define an angle in the range of approximately 13 degrees to approximately 16 degrees.

11. The two-stroke engine as set forth in claim 4 , wherein a longitudinal centerline of the cylinder and a longitudinal centerline of the slide stem intersect to define an angle in the range of approximately 10 degrees to approximately 45 degrees.

12. The two-stroke engine as set forth in claim 5 , wherein a longitudinal centerline of the cylinder and a longitudinal centerline of the slide stem intersect to define an angle in the range of approximately 10 degrees to approximately 45 degrees.

13. The two-stroke engine as set forth in claim 2 , wherein the control slide is topped by a male threaded pin-shaped portion engageable with a female threaded shell portion of the slide stem.

14. The two-stroke engine as set forth in claim 4 , wherein the control slide is topped by a male threaded pin-shaped portion engageable with a female threaded shell portion of the slide stem.

15. The two-stroke engine as set forth in claim 5 , wherein the control slide is topped by a male threaded pin-shaped portion engageable with a female threaded shell portion of the slide stem.

16. The two-stroke engine as set forth in claim 2 , wherein a top surface of the main member is upswept from at least one auxiliary member toward the slide stem.

17. The two-stroke engine as set forth in claim 4 , wherein a top surface of the main member is upswept from at least one auxiliary member toward the slide stem.

18. The two-stroke engine as set forth in claim 6 , wherein a top surface of the main member is upswept from at least one auxiliary member toward the slide stem.

19. The two-stroke engine as set forth in claim 2 , wherein the auxiliary members protrude from the main member at any position in relation to the upright axis of the main member.

20. The two-stroke engine as set forth in claim 19 , wherein the auxiliary members protrude below a bottom surface of the main member.

21. The two-stroke engine as set forth in claim 13 , wherein the auxiliary members protrude from the main member at any position in relation to the upright axis of the main member.

22. The two-stroke engine as set forth in claim 16 , wherein the auxiliary members protrude from the main member at any position in relation to the upright axis of the main member.

23. The two-stroke engine as set forth in claim 2 , wherein the slide stem comprises a cylindrical portion slidably seated in a cylindrical recess in the cylinder.

24. The two-stroke engine as set forth in claim 1 , wherein the actuator is disposed proximate to the cylinder head and is adapted for gas pressurization and coupling with the slide stem.

25. The two-stroke engine as set forth in claim 24 , wherein the actuator comprises two pistons, with at least one piston face each, which actuate the slide stem to overcome a spring bias to uncover the exhaust ports, and wherein the piston faces of the two pistons are offset axially in relation to the direction of an actuating force.

26. The two-stroke engine as set forth in claim 24 , wherein the actuator is actuatable by means of exhaust gas, and is in fluid communication with at least one of the exhaust ports.

27. The two-stroke engine as set forth in claim 24 , wherein the actuator comprises a housing having two pressure chambers therein, juxtaposed by expansion chambers for venting or negative pressurizing.

28. The two-stroke engine as set forth in claim 27 , wherein the actuator further comprises flexible pressure diaphragms disposed between pot-shaped housing members and a partition between the pressure chambers, the diaphragms supported by piston faces on a first and a second piston, and wherein the first and second pistons are coupled to move together always to actuate the slide stem.

29. The two-stroke engine as set forth in claim 28 , wherein the pressure diaphragms comprise a methyl vinyl silicone rubber.

30. The two-stroke engine as set forth in claim 29 , wherein the pressure diaphragms comprise fluorosilicone rubber fluoromethyl polysiloxane.

31. The two-stroke engine as set forth in claim 1 , further comprising:

a recess, defined in the cylinder and configured substantially complementary in shape and size to the control slide, for slidably receiving the control slide; and

a hole, with the recess, for slidably receiving the slide stem.

32. The two-stroke engine as set forth in claim 1 , wherein the cylinder has an upright axis, and wherein when the control slide is in a non-actuated position, a lower metering edge of the auxiliary exhaust port is disposed substantially level with a lower metering edge of the main member.

33. The two-stroke engine as set forth in claim 1 , wherein the main member of the control slide comprises, at a lower metering edge thereof, a recess, and the recess defining an upsweep which is reduced in the direction of the main exhaust port such that, when the main exhaust port is uncovered, the lower metering edge is substantially flush with an upper edge of the main exhaust port.

34. The two-stroke engine as set forth in claim 1 , wherein the actuator comprises a gas-pressurized piston which actuates the slide stem, the actuator being actuatable by exhaust gas of the engine.

35. The two-stroke engine as set forth in claim 1 , wherein the actuator comprises a gas-pressurized piston which actuates the slide stem, the actuator being actuatable by a gas pressurized in a crankcase of the engine.

36. The two-stroke engine as set forth in claim 1 , wherein the actuator is electromechanically powered.

37. The two-stroke engine as set forth in claim 1 , wherein the engine is disposed on a motorcycle.