Exhaust timing control for a planing-type boat

Abstract

A two-cycle internal combustion engine for a watercraft that includes a cylinder block having a cylinder bore, a piston reciprocating in the cylinder bore and an exhaust port formed in the cylinder block. An exhaust path extends from the cylinder bore for exhausting combustion products from the cylinder bore. An exhaust control valve cooperates with the exhaust port and is movable between at least a first position for advancing the closing of the exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of the exhaust port so as to decrease the compression ratio in the engine. Means for controlling the exhaust control valve between the first and second position are provided and are controlled in response to a watercraft condition.

What is claimed is:  
     
       1. A two-cycle internal combustion engine for a watercraft, said engine comprising a cylinder block having a cylinder bore, a piston reciprocating in said cylinder bore, an exhaust port formed in said cylinder block extending from said cylinder bore for exhausting combustion products from said cylinder bore, an exhaust control valve cooperable with said exhaust port and movable between at least a first position for advancing the closing of said exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of said exhaust port so as to decrease the compression ratio in the engine, and means for controlling the position of said exhaust control valve dependent upon a water  watercraft condition. 
     
     
       2. The two-cycle engine in accordance with  claim 1 , wherein the watercraft condition is a planing condition of the watercraft. 
     
     
       3. The two-cycle engine in accordance with  claim 2 , wherein said exhaust valve control valve controlling means moves said valve to a first position when said watercraft is not planed, and moves said valve to a second position subsequent to said watercraft reaching a planing velocity. 
     
     
       4. The two-cycle internal combustion engine of  claim 1 , wherein the watercraft condition is watercraft velocity. 
     
     
       5. The two-cycle internal combustion engine of  claim 4 , wherein said exhaust control valve controlling means moves said valve to a first position prior to the watercraft reaching a planing transition velocity and moves said valve to a second position subsequent to said watercraft reaching a planing transition velocity. 
     
     
       6. A two-cycle internal combustion engine for a watercraft, said engine comprising a cylinder block having a cylinder bore, a piston reciprocating in said cylinder bore, an exhaust port formed in said cylinder block extending from said cylinder bore for exhausting combustion products from said cylinder bore, an exhaust control valve cooperable with said exhaust port and movable between at least a first position for advancing the closing of said exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of said exhaust port so as to decrease the compression ratio in the engine, and means for controlling said exhaust control valve between said first and second position dependent upon a planing condition of said watercraft. 
     
     
       7. The two-cycle engine in accordance with  claim 6 , wherein said means controls said valve to be in said first position when said watercraft is not in a planed condition and to be in said second position when said watercraft is in a planed condition. 
     
     
       8. A two-cycle internal combustion engine for a watercraft, said engine comprising a cylinder block having a cylinder bore, a piston reciprocating in said cylinder bore, an exhaust port formed in said cylinder block extending from said cylinder bore for exhausting combustion products from said cylinder bore, an exhaust control valve cooperable with said exhaust port and movable between at least a first position for advancing the closing of said exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of said exhaust port so as to decrease the compression ratio in the engine, and means for electrically controlling said exhaust control valve between said first and second position based on a condition of said watercraft. 
     
     
       9. A two- cycle internal combustion engine for a watercraft, said engine comprising a cylinder block, a cylinder bore formed in said cylinder block, a piston disposed within said cylinder bore, an exhaust port formed in said cylinder block extending from said cylinder bore through which combustion products are exhausted from said cylinder bore, an exhaust control valve cooperable with said exhaust port and moveable between at least a first position for advancing the closing of said exhaust port so as to increase the compression ratio of the engine and a second position for delaying the closing of said exhaust port so as to decrease the compression ratio of the engine, and an actuator system being operably connected to the exhaust control valve, the actuator system being capable of moving the exhaust control valve based upon at least one watercraft condition.   
     
     
       10. The engine of  claim 9 , wherein said actuator system comprises a control unit. 
     
     
       11. The engine of  claim 10 , wherein said watercraft condition is a watercraft planing condition. 
     
     
       12. The engine of  claim 11 , wherein said actuator system is adapted to move said exhaust control valve to said first position when said watercraft is not planing and said actuator system is adapted to move said exhaust control valve to said second position when said watercraft is planing. 
     
     
       13. The engine of  claim 11 , wherein said planing condition is indicated, at least in part, by a preset velocity of said watercraft and said control unit receives an input velocity signal from a watercraft velocity sensor. 
     
     
       14. The engine of  claim 13 , wherein said actuator system is adapted to move the exhaust control valve based at least in part upon said input velocity signal from said watercraft velocity sensor. 
     
     
       15. The engine of  claim 13 , wherein said actuator system is adapted to move said exhaust control valve to said first position when said watercraft is not planing and said actuator system is adapted to move said exhaust control valve to said second position subsequent to said watercraft reaching a planing velocity. 
     
     
       16. The engine of  claim 10 , wherein said watercraft condition is watercraft velocity. 
     
     
       17. The engine of  claim 16 , wherein said actuator system is adapted to move said exhaust control valve to said first position prior to said watercraft reaching a planing transition velocity and said actuator system is adapted to move said exhaust control valve to said second position subsequent to said watercraft reaching said planing transition velocity. 
     
     
       18. The engine of  claim 9 , wherein said exhaust control valve is rotatably mounted in said cylinder block. 
     
     
       19. The engine of  claim 9 , wherein said actuator system further comprises a motor connected to said exhaust control valve, said motor being capable of moving said exhaust control valve. 
     
     
       20. The engine of  claim 19 , wherein said actuator system further comprises a flexible loop that connects said motor to said exhaust control valve. 
     
     
       21. The engine of  claim 20 , wherein said actuator system comprises a pulley connected to said exhaust control valve and said flexible loop wraps around at least a portion of said pulley. 
     
     
       22. The engine of  claim 19 , wherein said motor is a stepper motor. 
     
     
       23. An internal combustion engine for a watercraft, said engine comprising a cylinder block having a cylinder bore, a piston reciprocating in said cylinder bore, an exhaust port formed in said cylinder block extending from said cylinder bore for exhausting combustion products from said cylinder bore, an exhaust control valve cooperable with said exhaust port and movable between at least a first position for advancing the closing of said exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of said exhaust port so as to decrease the compression ratio in the engine, and an actuator system adapted to control the position of said exhaust control valve dependent upon at least one watercraft condition. 
     
     
       24. The engine of  claim 23 , wherein said actuator system comprises a control unit. 
     
     
       25. The engine of  claim 24 , wherein said watercraft condition is a watercraft planing condition. 
     
     
       26. The engine of  claim 25 , wherein said actuator system is adapted to move said exhaust control valve to said first position when said watercraft is not planing and said actuator system is adapted to move said exhaust control valve to said second position when said watercraft is planing. 
     
     
       27. The engine of  claim 25 , wherein said planing condition is indicated, at least in part, by a preset velocity of said watercraft and said control unit receives an input velocity signal from a watercraft velocity sensor. 
     
     
       28. The engine of  claim 27 , wherein said actuator system is adapted to move the exhaust control valve based at least in part upon said input velocity signal from said watercraft velocity sensor. 
     
     
       29. The engine of  claim 27 , wherein said actuator system is adapted to move said exhaust control valve to said first position when said watercraft is not planing and said actuator system is adapted to move said exhaust control valve to said second position subsequent to said watercraft reaching a planing velocity. 
     
     
       30. The engine of  claim 24 , wherein said watercraft condition is watercraft velocity. 
     
     
       31. The engine of  claim 23 , wherein said actuator system is adapted to move said exhaust control valve to said first position prior to said watercraft reaching a planing transition velocity and said actuator system is adapted to move said exhaust control valve to said second position subsequent to said watercraft reaching said planing transition velocity. 
     
     
       32. The engine of  claim 23 , wherein said exhaust control valve is rotatably mounted in said cylinder block. 
     
     
       33. The engine of  claim 23 , wherein said actuator system further comprises a motor connected to said exhaust control valve, said motor being capable of moving said exhaust control valve. 
     
     
       34. The engine of  claim 33 , wherein said actuator system further comprises a flexible loop that connects said motor to said exhaust control valve. 
     
     
       35. The engine of  claim 34 , wherein said actuator system comprises a pulley connected to said exhaust control valve and said flexible loop wraps around at least a portion of said pulley. 
     
     
       36. The engine of  claim 33 , wherein said motor is a stepper motor.