Lubrication system for two-cycle engine Number:7,150,249 from the United States Patent and Trademark Office (PTO) owispatent 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.<H Lubrication, engine, Lubrication, sys, 7150249.html, Patent, pto, 7150249

Title: Lubrication system for two-cycle engine

Abstract: 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.

Patent Number: 7,150,249 Issued on 12/19/2006 to Kato

Inventors: Kato; Masahiko (Shizuoka, JP)
Assignee: Yamaha Marine Kabushiki Kaisha (Shizuoka, JP)

Appl. No.: 10/439,049

Filed: May 15, 2003

Foreign Application Priority Data


May 20, 2002 [JP]			2002-144658

Current U.S. Class: 123/73AD ; 123/196R

Current International Class: F01M 1/16 (20060101)

Field of Search: 123/196R,73AD

References Cited [Referenced By]

U.S. Patent Documents


4726330	February 1988	Shiga
4967700	November 1990	Torigai
4989555	February 1991	Matsuo et al.
5062399	November 1991	Nagakura et al.
5067454	November 1991	Waddington et al.
5287833	February 1994	Yashiro
5353759	October 1994	Abe et al.
5355851	October 1994	Kamiya
5370089	December 1994	Harada
5390635	February 1995	Kidera et al.
5511524	April 1996	Kidera et al.
5522370	June 1996	Katoh et al.
5526783	June 1996	Ito et al.
5597051	January 1997	Moriya et al.
5630383	May 1997	Kidera et al.
5787847	August 1998	Ozawa et al.
5829401	November 1998	Masuda
5934242	August 1999	Anamoto
6516756	February 2003	Kato et al.

Foreign Patent Documents


10-37730	Feb., 1998	JP

Primary Examiner: Solis; Erick R
Attorney, Agent or Firm: Knobbe, Martens, Olson & Bear, LLP

Claims

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.

Description

PRIORITY INFORMATION

This application is based on and claims priority under 35 U.S.C. .sctn.119 to Japanese Patent Application Nos. 2002-144658, filed on May 20, 2002, the entire contents of which is hereby expressly incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to a lubrication system for a two-cycle engine, and more particularly a lubrication system that incorporates a lubrication pump that periodically pressurizes lubricant to a portion of a two-cycle engine.

2. Description of Related Art

In all fields of engine design, there is an increasing emphasis on obtaining more effective emission control. Recent two-cycle engines, therefore, incorporate a lubricant pump to deliver a desired amount of lubricant to lubricate internal portions of the engines. Mechanically operated pumps can be used as the lubricant pump. Such mechanical pumps, however, are not easily controlled to provide highly precise amounts of lubricant in response to engine operations. Electrically operable pumps tend to replace the mechanical pumps because higher precision controls are more widely available with such electrical pumps.

The electrical pumps can periodically pressurize lubricant under control of a control device such as, for example, an electronic control unit (ECU). The ECU can control a frequency of the periodic pressurization with, for example, an electronic control signal configured to operate the pump in accordance with a desired duty cycle. The higher the frequency, the greater the amount of the lubricant.

An electromagnetic solenoid pump is one type of such electrical pump. Japanese Laid Open Patent Publication 10-37730 discloses a lubrication system incorporating such an electromagnetic solenoid pump. The solenoid pump has a pumping piston reciprocally disposed in a pump housing. A plunger is coupled with the pumping piston. An electromagnetic solenoid can actuate the plunger. A control device controls the solenoid to selectively actuate or release the plunger such that the pumping piston periodically pressurizes the lubricant.

The control device has a control map including an amount of lubricant required by the engine versus an engine speed and determines a frequency of energization of the solenoid using the control map.

SUMMARY OF THE INVENTION

One aspect of at least one of the inventions disclosed herein includes the realization that the frequency and/or the ON-time of a lubrication pump can be adjusted to overcome problems associated with low speed, low load, and low temperature operation. During normal operation, e.g., operation at normal lubricant temperatures, above-idle engine speeds or higher engine loads, the frequency of pump actuation can be determined such that an ON-time of the solenoid is fixed to a constant period of time that is the maximum period of time in which the pumping piston can fully move. In other words, the maximum period of time corresponds to an ON-time sufficient to move the piston of the lubrication pump over a full stroke.

Although the ON-time can be set longer than the "maximum time", no further movement of the piston will result because the piston will have reached a limit of travel. Additionally, if the ON-time is set longer than the time sufficient to cause the piston to move over an entire stroke, there will be less time to allow the piston to return to its initial position and begin the next stroke. Thus, the maximum ON-time used will generally be that time sufficient to cause the piston to move from one to another extreme position, i.e., a "full stroke". Additionally, the phrase "maximum time" could also be expressed as a minimum time required for a piston of the lubrication pump to move over a full stroke.

An OFF-time of the solenoid typically will include a sufficient period of time in which the pumping piston can return to an initial position. In determining the frequency, the control device can take account of an engine load alternatively or in addition to the engine speed.

Under normal operation, the determination of the frequency based on engine speed or load works satisfactorily when the engine speed is greater than a preset speed, e.g., the engine speed is in a middle or high speed range, or the engine load is greater than a preset load, e.g., the engine load is in a middle or high load range. This is because the engine requires a larger amount of lubricant in those ranges, causing the pump to operate almost continuously. However, is has been discovered that the lubricant can be insufficient, particularly at the end of the OFF-time of the solenoid when the engine speed is less than the preset speed and the engine load is less than the preset engine load, i.e., in a low speed and low load range because the engine requires a small amount of lubricant and the lubrication pump intermittently delivers the lubricant. This problem is more significant where a large size pump is used, that has a large dynamic range.

Generally, a pump with a longer piston stoke is more efficient for delivering lubricant, i.e., a greater volume per piston stroke. However, a longer stroke can cause a problem such that the pumping piston cannot complete a full stroke at an acceptable speed in low temperature due to the high viscosity of the lubricant. The pumping efficiency thus falls in low temperature accordingly.

The control device can apply a feed-back control (PI control) to control the lubricant pump because the feed-back control is particularly suitable for an engine assembled with various components and members that have tolerances, for an engine lubricated by an unspecified lubricant (e.g., having different viscosity) and for an engine used under unspecified conditions (e.g., under a different lubricant temperature).

In accordance with another aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. At least one sensor senses either an engine speed or an engine load of the engine. A control device controls the lubrication pump. The control device determines a frequency of the periodic pressurization based upon a signal from the sensor. 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 signal from the sensor indicates that the engine speed is less than a preset engine speed or the engine load is less than a preset engine load.

In accordance with a further aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. A sensor senses either an engine speed or an engine load of the engine. A control device controls the lubrication pump. The control device primarily determines a frequency of the periodic pressurization based upon a signal from the sensor. The control device adjusts the frequency such that the adjusted frequency is higher than the primarily determined frequency, when a signal from the sensor indicates that the engine speed is less than a preset engine speed or the engine load is less than a preset engine load.

In accordance with another aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. A sensor senses either an engine speed or an engine load of the engine. A control device controls the lubrication pump. The control device primarily determines a frequency of the periodic pressurization based upon a signal from the sensor. The control device adjusts the frequency such that the adjusted frequency is higher than the primarily determined frequency, when a signal from the sensor indicates that the engine speed is less than a preset engine speed or the engine load is less than a preset engine load.

In accordance with another aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system configured to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. A first sensor senses an operational condition of the engine. A second sensor senses a temperature of the lubricant. A control device controls the lubrication pump. The control device is configured to determine a first frequency of periodic pressurization based upon a signal from the first sensor. The control device is also configured to adjust the frequency such that the adjusted frequency 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.

In accordance with a further aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. A first sensor senses either an engine speed or an engine load of the engine. A second sensor senses a temperature of the lubricant. A control device controls the lubrication pump. The control device is configured to determine a first frequency of the periodic pressurization based upon a signal from the first sensor. The control device is also configured to adjust the frequency such that the adjusted frequency is higher than the first frequency 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 from the second sensor indicating that the temperature of the lubricant is less than a preset temperature.

In accordance with a yet another aspect of at least one of the inventions disclosed herein, an internal combustion engine has a lubrication system to lubricate at least a portion of the engine with lubricant. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. A first sensor senses an operational condition of the engine. A second sensor senses an actual amount of the lubricant delivered to the lubrication pump. A control device controls the lubrication pump. The control device determines a frequency of the periodic pressurization based upon a signal from the first sensor. The higher the frequency the more the actual amount of the lubricant. The control device determines a target amount of the lubricant based upon a signal from the first sensor. The control device adjusts the frequency with a first adjustment amount of the lubricant when the actual amount differs from the target amount. The control device further adjusts the frequency with a second adjustment amount of the lubricant when the actual amount still differs from the target amount. The first adjustment amount is greater than the second adjustment amount.

In accordance with a further aspect of at least one of the inventions disclosed herein, a method is provided for controlling a lubrication system that lubricates at least a portion of an engine. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. The method includes 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 less than a preset engine speed or the engine load is 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.

In accordance with a further aspect of at least one of the inventions disclosed herein, a method is provided for controlling a lubrication system that lubricates at least a portion of an engine. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. The method includes 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 less than a preset engine speed or the engine load is less than a preset engine load, and adjusting the frequency such that the adjusted frequency is higher than the determined frequency when the determination of the engine speed or the engine load is affirmative.

In accordance with a still further aspect of at least one of the inventions disclosed herein, a method is provided for controlling a lubrication system that lubricates at least a portion of an engine. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. The method includes sensing an operational condition of the engine, sensing a temperature of the lubricant, determining a frequency of the periodic pressurization based upon the operational condition of the engine, determining whether the temperature of the lubricant is less than a preset temperature, and adjusting the frequency such that the adjusted frequency is higher than the determined frequency when the determination of the temperature is affirmative.

In accordance with a still further aspect of at least one of the inventions disclosed herein, a method is provided for controlling a lubrication system that lubricates at least a portion of an engine. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. The method includes sensing either an engine speed or an engine load of the engine, sensing a temperature of the lubricant, determining a frequency of the 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, and adjusting the frequency such that the adjusted frequency is higher than the determined frequency when the determination of the engine speed or the engine load is affirmative or the determination of the temperature is affirmative.

In accordance with a still further aspect of at least one of the inventions disclosed herein, a method is provided for controlling a lubrication system that lubricates at least a portion of an engine. The lubrication system has a lubrication pump that periodically pressurizes the lubricant toward the portion of the engine. The method includes sensing an operational condition of the engine, sensing an actual amount of the lubricant to the lubrication pump, determining a frequency of the periodic pressurization based upon the operational condition of the engine, the higher the frequency the more the actual amount of the lubricant, determining a target amount of the lubricant based upon the operational condition of the engine, determining whether the actual amount differs from the target amount, adjusting the frequency with a first adjustment amount of the lubricant when the determination of the difference is affirmative, determining whether the actual amount still differs from the target amount, and adjusting the frequency with a second adjustment amount of the lubricant when the second determination of the difference is affirmative. The first adjustment amount is greater than the second adjustment amount.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the inventions disclosed herein are described below with reference to the drawings of preferred embodiments, which are intended to illustrate and not to limit the inventions. The drawings comprise 17 figures in which:

FIG. 1 is a multi-part view showing in the lower right-hand portion, an outboard motor that employs an engine having a lubrication system which relates to the present inventions; in the upper view, a partially schematic cross-sectional view of the engine of the outboard motor with the lubrication system, an air induction system and a fuel injection system shown in part schematically; and in the lower left-hand portion, a rear elevational view of the outboard motor with portions removed and other portions broken away and shown in cross section of the upper view so as to more clearly illustrate the construction of the engine, with the fuel injection system shown schematically in part, wherein an ECU for the motor links the three views together;

FIGS. 2(A), (B) and (C) are schematic views of a lubrication pump applied in the lubrication system of FIG. 1; FIG. 2(A) illustrates a position in which the lubrication pump does not operate and all the members are in stationary positions thereof, FIG. 2(B) illustrates an electromagnetic solenoid of the lubrication pump actuating a plunger thereof under control of the ECU and a pumping piston of the pump pressurizing lubricant; and FIG. 2(C) illustrates a position in which the solenoid releases the plunger and the pumping piston returns to an initial position;

FIG. 3 is a flow chart illustrating a control routine for operating a lubrication pump in accordance with one embodiment of at least one of the inventions disclosed herein;

FIG. 4 is a chart illustrating an operational range of the engine in which an engine speed and a throttle valve opening (i.e., an indication of engine load) are parameters to determine the operational range, wherein the hatched area of the figure illustrates a range of a low engine speed and low load range;

FIG. 5 is a control map including a frequency of periodic pressurization of the lubrication pump versus the engine speed and the engine load of the engine, wherein the hatched area of the figure illustrates a frequency range corresponding to the low engine speed low load of the engine;

FIG. 6 is a control map including a period of ON-time of the solenoid versus engine speed and the engine load of the engine in a low engine speed and low engine load range of the engine;

FIG. 7 is a control map including the frequency versus the engine speed and the engine load of the engine in the low engine speed and low load range of the engine;

FIG. 8 is a flow chart illustrating a modified control routine for operating a lubrication pump in accordance with another embodiment of at least one of the inventions disclosed herein;

FIG. 9 is a chart illustrating a relationship between a temperature and a viscosity of the lubricant and also a relationship between a temperature of lubricant and an adjustment coefficient;

FIG. 10 is a control map including adjustment coefficients correlated with temperatures;

FIG. 11 is a flow chart illustrating another modified control routine for operating a lubrication pump in accordance with a further embodiment of at least one of the inventions disclosed herein;

FIG. 12 is a chart illustrating relationships between the temperature of the lubricant and an output efficiency of the lubrication pump when the ON-time of the solenoid is changed with several coefficients;

FIG. 13 is a flow chart illustrating a further modified control routine for operating a lubrication pump in accordance with a still further embodiment of at least one of inventions disclosed herein;

FIG. 14 is a flow chart illustrating a still further modified control routine for operating a lubrication pump in accordance with an yet further embodiment of at least one of inventions disclosed herein;

FIG. 15 is a chart illustrating a change in a flow amount of the lubricant versus time and a change of a control amount in a feed-back control that converges an actual amount to a target amount.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Overall Construction of Outboard Motor and a Two-Cycle Engine

With reference to FIG. 1, an exemplifying environment in which the present inventions can be practiced are described below. The present lubrication system described below has particular utility in the context of a two-cycle engine for an outboard motor, and thus, is described in the context of such an outboard motor. The lubrication system, however, can be used with other types of two-cycle engines employed by any machines whatsoever using engine power such as, for example, watercrafts, land vehicles and utility machines.

With particular reference to the lower-right hand view of FIG. 1, an outboard motor 30 is depicted in a left side elevational view. The outboard motor 30 has a bracket assembly 31 comprising a swivel bracket and a clamping bracket which are typically associated with a driveshaft housing 32.

The outboard motor 30 includes a power head 34 that is positioned above the driveshaft housing 32. The power head 34 comprises a protective cowling assembly and an internal combustion engine 36. This engine 36 is illustrated in greater detail in the remaining two views of this figure, and is described in greater detail below.

The protective cowling assembly includes a top cowling member 38 and a bottom cowling member 40. The top and bottom cowling members 38, 40 together define a closed cavity in which the engine 36 is housed. The top cowling member 38 is detachably affixed to the bottom cowling member 40 such that a user or service person can access the engine 36 for maintenance service or other purposes. The top cowling member 38 preferably defines air intake openings on a rear, upper end surface. Air thus can be drawn into the cavity.

An engine support or exhaust guide 42 is unitarily or separately formed atop the driveshaft housing 32 and forms a tray together with the bottom cowling member 40. The tray can hold a bottom of the engine 36 and the engine 36 is affixed to the engine support 42.

The engine 36 comprises an engine body 45 (the upper and the lower-left hand views of FIG. 1) and a movable member which is movable relative to the engine body 45. The movable member in the illustrated engine 36 is a crankshaft 46 (the upper view of FIG. 1) that is rotatably journaled on the engine body 45. The crankshaft 46 rotates about a generally vertically extending axis. This facilitates the connection of the crankshaft 46 to a driveshaft (not shown) which depends into the driveshaft housing 32.

A lower unit 48 depends from the driveshaft housing 32. The propulsion device is mounted on the lower unit 48 and the driveshaft drives the propulsion device. The illustrated propulsion device is a propeller 49. The driveshaft drives the propeller 49 through a transmission disposed within the lower unit 48. The transmission includes a changeover mechanism that can change a rotational direction of the propeller 49 among forward, neutral and reverse. The propulsion device can take the form of a dual counter-rotating system, a hydrodynamic jet, or any of a number of other suitable propulsion devices.

With particular reference to the upper view and the lower left-hand view of FIG. 1, the engine 36 operates on a two-cycle, crankcase compression principle. The illustrated engine 36 is generally configured in a V-shape, with a pair of cylinder banks 50 extending generally rearwardly. Each bank 50 defines three cylinder bores 51. The cylinder bores 51 extend generally horizontally and are vertically spaced apart from each other in each bank 50. As used in this description, the term "horizontally" means that the subject portions, members or components extend generally in parallel to the water line where the associated watercraft is resting when the outboard motor 30 is not tilted. The term "vertically" in turn means that portions, members or components extend generally normal to those that extend horizontally. Although the invention is described in conjunction with the engine 36, the inventions disclosed herein can be utilized with an engine having other cylinder numbers and other cylinder configurations.

The engine body 45 includes a cylinder block 52. The cylinder block 52 forms the cylinder banks 50 in the illustrated arrangement. Other movable members are movable relative to the engine body 45. For example, other movable members in the illustrated engine 36 are pistons that are reciprocally disposed within the cylinder bores 51. The crankshaft 46 is journaled for rotation within a crankcase chamber defined in part by a crankcase member 60 that is affixed to the cylinder block 50 in a suitable manner. The pistons are coupled with the crankshaft 46 through connecting rods. The crankshaft 46 thus rotates with the reciprocal movement of the pistons.

Cylinder head assemblies 66 are affixed to each cylinder banks 50 to close open ends of the respective cylinder bores 51. Each cylinder head assembly 66 comprises a cylinder head member that defines a plurality of recesses (not shown) on its inner surface corresponding to the cylinder bores 51. Each of these recesses defines a combustion chamber together with the cylinder bore 51 and the piston. Cylinder head cover members complete the cylinder head assemblies 66. The cylinder head members and cylinder head cover members are affixed to each other and to the respective cylinder banks 50 in a suitable known manner.

The engine 36 preferably is provided with an air induction system 80 that delivers air to each section of the crankcase chamber associated with each cylinder bore 51. The induction system 80 comprises an air inlet device 82, an air intake manifold and a plurality of air intake conduits 84. The air inlet device 82 defines a plenum chamber through which the air is drawn into the induction system 80. The intake manifold is coupled with the inlet device 82. Each air intake conduit 84 is branched off from the intake manifold and defines an air intake passage connecting the plenum chamber and each section of the crankcase chamber associated with each combustion chamber. The air drawn into the plenum chamber thus is delivered to the sections of the crankcase chamber through the intake conduits 84.

Each intake conduit 84 preferably incorporates a reed valve 88 that allows the air to flow into the section of the crankcase chamber 60 and prevents the air in the section of the crankcase member 60 from flowing back to the plenum chamber. Each intake conduit 84 also incorporates a throttle valve 90 between the plenum chamber and the reed valve 88. Each throttle valve 90 is pivotally journaled on each intake conduit 84 to regulate an amount of flowing therethrough. The operator can change the pivotal position, i.e., throttle position, through a suitable control mechanism (not shown).

The air drawn into the respective sections of the crankcase chamber is preliminary compressed by the pistons, during their movement toward the crankshaft. The air, then, moves into the combustion chambers through a scavenge system. The scavenge system preferably is formed as a Schnurle-type system that comprises a pair of main scavenge passages connected to each cylinder bore 51 and positioned on diametrically opposite sides. These main scavenge passages terminate in main scavenge ports so as to direct scavenge air flows into the combustion chamber.

In addition, an auxiliary scavenging passage is formed between the main scavenge passages and terminates in an auxiliary scavenging port which also provides a scavenge air flow. Thus, at the scavenge stroke, the air in the crankcase chamber is transferred to the combustion chambers to be further compressed by the pistons during their movement toward the head member. The scavenge ports are selectively opened and closed as the piston reciprocates.

The engine 36 preferably is provided with a fuel supply system 94 that delivers fuel to the combustion chambers. The illustrated fuel supply system 94 is configured to operate under a direct fuel injection principle in which the fuel is directly sprayed into the combustion chambers.

The fuel supply system 94 comprises fuel injectors 98 allotted to the respective combustion chambers. The fuel injectors 98 preferably are mounted on the cylinder head assemblies 66. An electronic control unit (ECU) 100 controls the fuel injectors 98 to inject fuel. The ECU 100 preferably controls the duration of each injection.

The ECU 100 comprises at least a central pressing unit (CPU) and at least one memory portion. The ECU 100 controls engine components such as, for example, the fuel injectors 98, in response to conditions collected by sensors. The memories store control programs and control references.

In the illustrated ECU 100, the memories store control maps, described below, as the control references. The CPU executes the control routines with reference to the control maps based upon signals from the sensors and sends control signals to the engine components. The sensors are described in greater detail below.

The fuel supply system 94 additionally comprises a fuel supply tank 104 that preferably is placed in the hull of the watercraft. A first low pressure pump 106 and one or a plurality of second low pressure pumps 108 draw the fuel from the tank 104 into a vapor separator 110. The first low pressure pump 106 can be a manually operated pump. The second low pressure pumps 108 preferably are diaphragm-type pumps operated by pulsation that occur in the sections of the crankcase chamber.

A quick disconnect coupling is provided in a conduit that connects the first low pressure pump 106 to the second low pressure pumps 108 to detachably connect the watercraft side of the conduit with the outboard side thereof. A fuel filter 112 is positioned between the first low pressure pump 106 and the second lower pressure pumps 108. The fuel filter 112 removes foreign substances such as, for example, particles and water in the fuel.

The illustrated vapor separator 110 is a fuel reservoir in which the fuel can be reserved. The vapor separator 110 has an inner construction that can separate vapor from the fuel to prevent the vapor lock from occurring in the fuel supply system 94.

An electric pump 116 preferably is disposed in the cavity of the vapor separator 110. The electric pump 116 pressurizes the fuel in the vapor separator 110 to a high pressure pump unit 118 through a preload (or pre-pressure) fuel passage 120. The pressure developed by the electric pump 116 is greater than the pressure developed by the low pressure pumps 108; however, is less than a pressure developed by the high pressure pump unit 118. In other words, the electric pump 116 develops a pressure to a certain level and the high pressure pump unit 130 raises the pressure to a higher level.

A preload regulator 124 is provided in a return passage 126 connecting the preload fuel passage 120 with the vapor separator 110 to return excessive fuel to the vapor separator 110. As such, the preload regulator 124 limits the pressure that is delivered to the high pressure fuel pump unit 118 by dumping fuel back to the vapor separator 110, and thereby bleeding pressure in excess of the pressure at which the regulator 124 is configured to open.

The high pressure pump unit 118 preferably comprises a pair of high pressure pumps 130. The illustrated preload passage 120 is bifurcated into two sections and is connected to the pumps 130. High pressure fuel passages 132 extend from the respective pumps 130. Flexible conduits preferably define the fuel passages 132. High pressure regulators 134 are disposed in the respective fuel passages 132 to regulate the high pressure at a fixed or constant high pressure. Excessive fuel returns back to the vapor separator 110 through return passages 134.

The high pressure pump unit 118 preferably is disposed atop and at the rear of the cylinder block 52. More specifically, the illustrated pump unit 118 is generally positioned between both of the banks 50. The pump unit 118 is affixed to the cylinder block 52 so as to overhang between the two banks 52 of the V arrangement. In the illustrated arrangement, the high pressure pump unit 118 comprises a pump drive 138. The high pressure fuel pumps 130 are disposed on both sides of the pump drive 138 and affixed thereto.

The pump drive 138 has a driveshaft. A cam disc is affixed onto the driveshaft and is engaged with plungers of the respective high pressure pumps 130. The high pressure fuel pumps 130 pressurize the fuel with the plungers when the cam disc pushes the plungers when the driveshaft rotates. A driven pulley preferably is affixed atop of the driveshaft. Also, a drive pulley is affixed atop of the crankshaft 46. An endless drive belt is wound around the driven and drive pulleys. The crankshaft 46 thus drives the driveshaft of the pump drive 138.

The high pressure fuel passages 132 are connected to respective fuel rails 142. The fuel rails 142 couple the fuel passages 132 with the respective fuel injectors 98. The fuel rails 142 are affixed to the respective cylinder head assemblies 66 so as to extend generally vertically. Preferably, the fuel injectors 98 are coupled to the fuel rails 142 with the respective internal fuel paths of the injectors 98 connected with the internal passages of the fuel rails 142. Additionally, the fuel injectors 98 preferably are affixed to each cy