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An engine has a lubrication system that lubricates the engine with lubricant. The lubrication system incorporates a lubrication pump that periodically pressurizes the lubricant toward the engine. An engine speed sensor and a throttle valve position sensor are provided to sense an engine speed and a

An engine has a lubrication system that lubricates the engine with lubricant. The lubrication system incorporates a lubrication pump that periodically pressurizes the lubricant toward the engine. An engine speed sensor and a throttle valve position sensor are provided to sense an engine speed and a throttle valve position (i.e., engine load), respectively. A control device controls the lubrication pump. The control device determines a frequency of the periodic pressurization based upon signals from the sensors. The control device sets a pressurizing time of the lubrication pump to a period of time shorter than the maximum period of time that can be set for the lubrication pump at the determined frequency, when the signals from the sensors indicate that the engine speed is less than a preset engine speed and the engine load is less than a preset engine load.

대표청구항 ▼

What is claimed is: 1. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, at least one sen

What is claimed is: 1. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, at least one sensor configured to sense either an engine speed or an engine load of the engine, and a control device configured to control the lubrication pump, the control device is also configured to determine a frequency of periodic pressurization based upon a signal from the sensor, the control device configured to set a pressurizing time of the lubrication pump to a period of time shorter than the maximum period of time that is capable to be set for the lubrication pump at the determined frequency, when the signal from the sensor indicates that the engine speed is within a range of engine speeds less than a preset engine speed or the engine load is within a range of engine loads less than a preset engine load. 2. The engine as set forth in claim 1, wherein the control device has a control reference correlating frequency and engine speed or engine load, the control device being configured to determine the frequency by referring the control reference. 3. The engine as set forth in claim 1, wherein the control device is configured to set the pressurizing time to a maximum period of time when the signal from the sensor indicates that the engine speed or the engine load is greater than a preset engine speed or engine load. 4. The engine as set forth in claim 1 comprising an engine speed sensor and an engine load sensor, the control device being configured to set the pressurizing time to the shorter time when a signal from the engine speed sensor indicates that the engine speed is less than a preset engine speed and a signal from the engine load sensor indicates that the engine load is less than a preset engine load. 5. The engine as set forth in claim 4, wherein the control device is configured to set the pressurizing time generally to the maximum period of time when either a signal from the engine speed sensor indicates that the engine speed is greater than a preset engine speed or a signal from the engine load sensor indicates that the engine load is greater than a preset engine load. 6. The engine as set forth in claim 4 additionally comprising an engine body, and a movable member movable relative to the engine body, the engine speed sensor senses a moving speed of the movable member. 7. The engine as set forth in claim 6, wherein the movable member is a crankshaft of the engine. 8. The engine as set forth in claim 4 additionally comprising an engine body, a movable member movable relative to the engine body, the engine body and the movable member defining a combustion chamber, and an air intake system arranged to introduce air into the combustion chamber, the air intake system comprising a throttle valve configured to regulate an amount of the air, the engine load sensor being configured to sense a position of the throttle valve. 9. The engine as set forth in claim 8, wherein the movable member is a piston of the engine. 10. The engine as set forth in claim 1, wherein the lubrication pump comprises a pumping piston, a plunger coupled with the pumping piston, and an electromagnetic solenoid configured to actuate the plunger, the control device being configured to control the solenoid to selectively actuate or release the plunger such that the pumping piston periodically pressurizes the lubricant, and wherein the pressurizing time of the lubrication pump is a time period in which the solenoid actuates the plunger. 11. The engine as set forth in claim 10, wherein the maximum period of time is a time period in which the pumping piston moves over a maximum stroke. 12. The engine as set forth in claim 1, wherein the control device includes a control reference correlating a pressurizing time of the lubrication pump and the engine speed less than the preset engine speed or the engine load less than the preset engine load, the control device being configured to set the pressurizing time based upon the signal from the sensor by referring the control reference. 13. The engine as set forth in claim 1, wherein the control device is configured to adjust the frequency such that the adjusted frequency is higher than the determined frequency, when the signal from the sensor indicates that the engine speed is less than the preset speed or the engine load is less than the preset engine load. 14. The engine as set forth in claim 13, wherein the control device includes a control reference correlating a frequency of the periodic pressurization and an engine speed less than the preset engine speed or an engine load less than the preset engine load, the control device being configured to determine the frequency based upon a signal from the sensor by referring the control reference when the signal from the sensor indicates that the engine speed is less than the preset speed or the engine load is less than the preset engine load. 15. The engine as set forth in claim 1 additionally comprising an engine body, a movable member movable relative to the engine body, the engine body and the movable member defining a combustion chamber, and an air intake system arranged to introduce air into the combustion chamber, the lubrication pump being configured to inject the lubricant into the air intake system. 16. The engine as set forth in claim 1, wherein the engine is configured to operate on a two-cycle combustion principle. 17. The engine as set forth in claim 1, wherein the maximum period of time is a minimum amount of time required for the lubrication pump to complete one stroke. 18. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump configured to periodically pressurize the lubricant toward the portion of the engine, a sensor configured to sense either an engine speed or an engine load of the engine, and a control device configured to control the lubrication pump, the control device configured to determine a first frequency of a periodic pressurization based upon a signal from the sensor, the control device configured to adjust the frequency such that the adjusted frequency is higher than the first frequency, when a signal from the sensor indicates that the engine speed is within a range of engine speeds less than a preset engine speed or the engine load is within a range of engine loads less than a preset engine load. 19. The engine as set forth in claim 18, wherein the control device has a control reference correlating frequency and engine speed or the engine load, the control device being configured to determine the first frequency by referring the control reference. 20. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump that periodically pressurizes lubricant toward the portion of the engine, a first sensor configured to sense an operational condition of the engine, a second sensor configured to sense a temperature of the lubricant, and a control device configured to control the lubrication pump, the control device configured to determine a first frequency based upon a signal from the first sensor, the control device determining a second frequency of the periodic pressurization that is higher than the first frequency when a signal from the second sensor indicates that the temperature of the lubricant is less than a preset temperature, wherein the control device is configured to set a pressurizing time of the lubrication pump to a period of time shorter than the maximum period of time that can be set for the lubrication pump at the frequency determined in referring to the control reference, when the signal from the second sensor indicates that the temperature of the lubricant is less than the preset temperature. 21. The engine as set forth in claim 20, wherein the control device includes a control reference correlating frequency and the operational condition of the engine, the control device being configured to determine at least one of ihe first and second frequencies by referring the control reference. 22. The engine as set forth in claim 20, wherein the control device is configured to set the pressuring time to the maximum period of time when the signal from the second sensor indicates that the temperature of the lubricant is greater than the preset temperature, wherein the maximum period of time corresponds to a time sufficient for causing a piston of the lubrication pump to complete an entire stroke. 23. The engine as set forth in claim 20, wherein the maximum period of time is a minimum amount of time required for the lubrication pump to complete one stroke. 24. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, a first sensor configured to sense either an engine speed or an engine load of the engine, a second sensor configured to sense a temperature of the lubricant, and a control device configured to control the lubrication pump, the control device configured to determine a first frequency of periodic pressurization based upon a signal from the first sensor, the control device also being configured to adjust the first frequency such that the adjusted first frequency is higher than the first frequency and to adjust a periodic pressurization time of the lubricant pump to a period of time shorter than that required for the pump to complete a full stroke when the control device receives a signal from at least one of the first sensor indicating that the engine speed is less than a preset engine speed or the engine load is less than a preset engine load, and the second sensor indicating that the temperature of the lubricant is less than a preset temperature. 25. The engine as set forth in claim 24, wherein the control device includes a control reference correlating frequency and the engine speed or the engine load, the control device being configured to determine the first frequency by referring the control reference. 26. An internal combustion engine comprising a lubrication system arranged to lubricate at least a portion of the engine with lubricant, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, a first sensor configured to sense an operational condition of the engine, a second sensor configured to sense an amount of lubricant delivered by the lubrication pump, and a control device configured to control the lubrication pump, the control device being configured to determine a frequency of periodic pressurization based upon a signal from the first sensor, wherein higher frequencies correspond to greater amounts of lubricant, the control device also being configured to determine a target amount of lubricant to be delivered by the lubricant pump based upon a signal from the first sensor, the control device further being configured to adjust the frequency with a first adjustment value when the sensed amount differs from the target amount, the control device being configured to adjust the frequency with a second adjustment value when the sensed amount differs from the target amount after the frequency has been adjusted by the first value, the first adjustment amount being greater than the second adjustment amount. 27. The engine as set forth in claim 26, wherein the control device is configured to determine whether a difference between the target amount and the sensed amount is greater than a preset difference, the control device being configured to store the difference when the control device determines that the difference between the target amount and the actual amount is greater than the preset difference. 28. The engine as set forth in claim 26 additionally comprising a warning device that configured to output a warning, the control device being configured to determine whether a difference between the target amount and the sensed amount is greater than a preset difference, the control device being configured to actuate the warning device when the control device determines that the difference between the target amount and the sensed amount is greater than the preset difference. 29. The engine as set forth in claim 26, wherein the control devices has a control reference correlating target amounts of lubricant and operational condition of the engine, the control device being configured to determine the target amount by referring to the control reference. 30. The engine as set forth in claim 26, wherein the control device has a control reference correlating frequencies and the operational conditions of the engine, the control device being configured to determine the frequency of the periodic pressurization by referring the control reference. 31. A method for controlling a lubrication system that lubricates at least a portion of an engine, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, the method comprising sensing at least one of an engine speed and an engine load of the engine, determining a frequency of the periodic pressurization based upon the engine speed or the engine load, determining whether the engine speed is within a range of engine speeds less than a preset engine speed or the engine load is within a range of engine loads less than a preset engine load, and setting a pressurizing time of the lubrication pump to a period of time shorter than the maximum period of time that is capable to be set for the lubrication pump, when the determination of the engine speed or the engine load is affirmative. 32. The method as set forth in claim 31 additionally comprising setting the pressurizing time generally to the maximum period of time when the determination of the engine speed or the engine load is negative, wherein the maximum period of time is a time sufficient for a piston of the lubrication pump to move over an entire stoke. 33. The method as set forth in claim 31 additionally comprising adjusting the frequency to a higher frequency than the determined frequency. 34. The method as set forth in claim 31, wherein the maximum period of time is a minimum amount of time required for the lubrication pump to complete one stroke. 35. A method for controlling a lubrication system that lubricates at least a portion of an engine, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, the method comprising sensing at least one of an engine speed and an engine load of the engine, determining a frequency of the periodic pressurization based upon at least one of the engine speed and the engine load, determining whether the engine speed is within a range of engine speeds less than a preset engine speed or the engine load is within a range of engine loads less than a preset engine load, and increasing the frequency when the determination of the engine speed or the engine load is affirmative. 36. A method for controlling a lubrication system that lubricates at least a portion of an engine, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, the method comprising sensing an operational condition of the engine, sensing a temperature of the lubricant, determining a frequency of periodic pressurization based upon the operational condition of the engine, determining whether the temperature of the lubricant is less than a preset temperature, increasing the frequency when the determination of the temperature is affirmative, and decreasing a duration of the periodic pressurization of the lubricant pump to a time period less than a minimum time reciuired for the pump to complete one stroke. 37. A method for controlling a lubrication system that lubricates at least a portion of an engine, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, the method comprising sensing at least one of an engine speed and an engine load of the engine, sensing a temperature of the lubricant, determining a frequency of periodic pressurization based upon the engine speed or the engine load, determining whether the engine speed is less than a preset engine speed or the engine load is less than the preset engine load, determining whether the temperature of the lubricant is less than a preset temperature, increasing the frequency when the determination of at least one of the engine speed, the engine load, and the temperature is affirmative, and decreasing a duration of the periodic pressurization of the lubricant pump to a time period less than a minimum time required for the pump to complete one stroke. 38. A method for controlling a lubrication system that lubricates at least a portion of an engine, the lubrication system having a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine, the method comprising sensing an operational condition of the engine, sensing an amount of the lubricant discharged from the lubrication pump, determining a frequency of periodic pressurization based upon the operational condition of the engine, wherein higher frequencies correspond to greater amounts of lubricant, determining a target amount of the lubricant based upon the operational condition of the engine, determining whether the sensed amount differs from the target amount, adjusting the frequency with a first adjustment value when the determination of the difference is affirmative, determining whether the actual amount differs from the target amount after the frequency has been adjusted with the first adjustment value, and adjusting the frequency with a second adjustment value when the second determination of the difference is affirmative, the first adjustment amount being greater than the second adjustment amount. 39. The method as set forth in claim 38 additionally comprising determining whether a difference between the target amount and the sensed amount is greater than a preset difference, and storing the difference when the determination of the difference magnitude is affirmative. 40. The method as set forth in claim 38 additionally comprising determining whether a difference between the target amount and the sensed amount is greater than a preset difference, and actuating a warning device when the determination of the difference magnitude is affirmative. 41. An internal combustion engine comprising: a lubrication system configured to lubricate at least a portion of the engine with a lubricant, the lubrication system including a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine; at least one sensor configured to sense at least one operational condition of the engine, the at least one operational condition of the engine comprising a speed of the engine, a load on the engine, a temperature of the lubricant, and an actual flow amount of the lubricant; and a control device configured to control the lubrication pump, to determine a frequency of the periodic pressurization based upon a signal from the at least one sensor, and configured to set a pressurizing time of the lubrication pump to a period of time shorter than a maximum period of time to be set for the lubrication pump at the determined frequency of the periodic pressurization when the at least one sensor indicates that the at least one operational condition of the engine is less than a preset operational condition of the engine. 42. The engine of claim 41, wherein the at least one sensor comprises a first sensor configured to detect the speed of the engine, the engine additionally comprising a second sensor configured to sense the load on the engine. 43. The engine of claim 41, wherein the at least one sensor comprises a first sensor configured to detect the speed of the engine or the load on the engine, the engine additionally comprising a second sensor configured to detect the temperature of the lubricant. 44. The engine of claim 41, wherein the at least one sensor comprises a first sensor configured to detect the speed of the engine or the load on the engine, the engine additionally comprising a second sensor configured to detect an actual flow of the lubricant. 45. The engine of claim 41, wherein the maximum period of time is a minimum amount of time required for the lubrication pump to complete one stroke.