Patent Application
20050092290
1. Field of the Invention
The present invention relates to an internal combustion engine revolution limiting apparatus, and in particular to a system and method for limiting maximum engine revolutions during a break-in period.
2. Description of the Prior Art
It is often recommended with internal combustion engines to limit the engine operating speed during an initial break-in period. Limiting the operating speed places less stress on the engine initially and allows components to seat relative to one another. Engine components operate without undue stress that might otherwise damage some of the components.
In the past, such limiting of engine speed was accomplished by simply informing operators that the engine should be operated at or below certain engine speed limits for specified initial time periods. However, an owner of a new vehicle often wants to test its speed and acceleration. The recommendations are ignored and damage to the engine may occur.
Devices and systems have been utilized that limit the engine operating speed during an initial break-in period and at other times when engine operating speed should be limited. For some applications, as the break-in period proceeds, it is desirable to increase the engine speed limit. Existing devices that limit revolutions during break-in do not provide for increasing the revolution limit.
Devices have been developed that provide for revolution limiting during a break-in period. U.S. Pat. No. 4,067,303 to Aoki shows a fuel injection pump governor. Although the device provides for limiting engine RPMs during a break-in period, the system uses a spring type governor that is mechanically actuated. The device must be manually reset after the break-in period. U.S. Pat. No. 6,044,822 to Daniels shows a programmed break-in mode in a two cycle engine. The Daniels patent teaches only control of an oil pump at two modes in a two cycle engine and does not provide variability and utilization with multiple different engines or multiple settings.
It can be seen that a new system and method for limiting engine speed during a break-in period is needed. Such a system should provide for variability of the break-in period and the engine limits. Moreover, the revolution limiting should utilize methods that provide for safe operation of the vehicle if the limit is reached during the break-in period. Multiple different time break-in periods and maximum engine speeds should be possible for gradual break-in. The present invention addresses these problems, as well as others associated with limiting engine speed during a break-in period.
The present invention is directed to an engine control system and in particular to an engine control system that limits engine speed during a break-in period. The engine control system provides for limiting or stopping firing of the ignition if selectable engine speed levels are exceeded during an initial, selectable break-in period. For example, during an initial eight hour break-in period, if an engine speed exceeds 4,000 RPM, ignition firing is limited. The control system provides for selecting one or more break in periods and associated engine speed limits. In addition, an over-revolution limit, which is greater than the revolution limit may also be selected wherein further engine controls are implemented.
The control system is programmed by setting an initial break-in period and an associated engine maximum speed level. In addition, an over-revolution speed level may also be selected that is higher than the maximum speed level in case of emergencies wherein limiting engine speed by limiting firing of the ignition is not sufficient. In addition to selecting an initial break-in period, multiple time periods with associated engine limits and over-revolution limits may also be preset and programmed into the control system. For example, an initial break-in period may last for eight hours with a first maximum engine speed of 4,000 RPM. However, a second period extending through sixteen hours of engine operating time may raise the limit to 5,000 RPM. It can be appreciated that any number of break-in periods and associated engine speeds may be utilized with the present system, as explained hereinafter. Such a system provides for allowing the engine speed to be increased as additional hours of operation allow for increasing stress on the engine as the likelihood of damage from the increased speed diminishes. When all of the preset operating break-in periods have expired, the engine is in normal operation mode with no revolution limits, or a normal operational rev limit that remains during all further engine operation.
In operation, when the engine has been started, a run-time monitor compares the accumulated engine run time to the predetermined break-in period. If the break-in period has not been exceeded, engine speed is compared to the associated revolution limit. This monitoring is continuous until the break-in period is completed. If the engine speed exceeds the revolution limit, ignition firing is limited. In a preferred embodiment, a “stuttering” type ignition firing method is used. Such a stuttering firing sequence may be firing the spark plugs twice in their normal sequence, then preventing them from firing twice from the normal sequence, or “missing,” in alternating steps. Other stuttering firing sequences that skip firings may also be utilized. This has advantages over methods that simply stop firing the ignition. The engine still has power, but with stuttering, tends to slow down from the limited firing of the ignition. The stuttering type engine firing continues as long as the engine speed is above the revolution limit. When the engine speed has gone below the revolution limit, normal continuous firing resumes.
In addition, the revolution limiter system may be modified so that the controller has an over-revolution limit that is greater than the revolution limit. A typical over-revolution limit might be approximately 256 RPM higher than the associated revolution limit. If the system's engine speed monitor determines that the revolution limit has been exceeded, it compares engine speed to the over-revolution limit, to determine whether it has been exceeded. If the over-revolution limit is exceeded, the firing to the ignition stops altogether until it is determined by the engine speed monitor that the engine speed is below the over-revolution limit. It can be appreciated that in some circumstances such as a vehicle going down hill, that limiting ignition firing may not slow down the engine sufficiently and engine speed may remain at an increased level. Therefore, the additional over-revolution limit is added. The system has advantages in that the engine operator will notice when the revolution limit is exceeded by the stuttering noise of the engine and will usually make manual adjustments to lower engine speed. This also provides for power from the engine for longer periods, giving the operator better control. However, if the revolution limiting is not sufficient to slow the engine, then the ignition firing stops. It is foreseen that if the operator is correctly operating the engine, the over-revolution limit should rarely be exceeded as the operator may manually limit operating speed once stuttering is detected.
It can also be appreciated that multiple break-in periods may be programmed. In operation, if the system's operating time monitor determines that an initial break-in period has expired, the monitor then determines whether there are two or more break-in periods. If the first break-in period has expired, but still other break-in periods have not expired, the associated revolution limit for the second and succeeding break-in periods will be compared to the engine speed. The additional break-in periods may also have associated over-revolution limits. With multiple break-in periods, the revolution limit is gradually increased as more operating time passes. When the monitoring system determines that all break-in periods have expired, the revolution limits are removed and the engine operates in a normal mode, which may or may not have a rev limit.
These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings that form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
Referring now to the drawings wherein like reference numerals and letters indicate corresponding structure throughout the several views:
Referring now to the drawings and in particular to
Referring now to
In addition, the present system also provides for inputting multiple break-in periods, each having an associated engine speed limit. For example, an initial break-in period of eight hours may be input with an associated engine maximum revolution limit of 4224 RPMs. This is represented by T1 and L1 in
Referring now to
In a preferred embodiment, once the revolution limit is exceeded and firing of the ignition is limited as at step 24, a particular firing sequence is engaged. In one embodiment, the engine ignition is fired twice as in a normal sequence and then the ignition skips two firings, or misses twice, as compared to the normal sequence when the revolution limiter detects that the over-revolution limit has been exceeded. In this mode, the engine will make a “stuttering” sound that is easily recognized and alerts the operator that the engine 10 is in a limiting mode and that the break-in revolution limit has been exceeded. Other stuttering firing sequences wherein the ignition skips firing in predetermined patterns may also be utilized. Engines having greater numbers of cylinders, such as 4, 6 or 8, may require particular stuttering firing sequences to reduce engine speed and power without damaging the engine. Such a firing sequence provides advantages over systems wherein the ignition is simply turned off. As the ignition fires spark plugs and then skips firing them in an alternating fashion, the engine continues to have power, although less power than in normal operating mode. In systems wherein the ignition is simply stopped once the engine revolution limit has been exceeded, the spark is simply turned off. The operator enjoys improved control and continued power with the present system while still achieving the advantages of limiting engine speed during the break-in period.
Referring now to
Referring to
If the first and second break-in periods have expired, the control system 14 checks to see whether a third break-in period, or additional periods as represented by TN, have been set. If the engine run time is less than the break-in period TN, the monitoring system 14 compares engine speed to the corresponding revolution limit as represented at 222. If it has been exceeded, firing of the ignition is limited as shown at step 224. Although three break-in periods and corresponding revolution limits are shown in
Referring to
In addition, in a manner similar to
If the engine run time is greater than the second time limit T2, the control system 14 checks for a third break-in period T3 as represented by step 220. If the engine run time is less than the break-in period, the engine ignition may be limited if the rev limit is exceeded, as at step 224. The monitoring system 14 then compares the engine speed to the over revolution limit O3 at 226 and, if the over revolution limit is exceeded, firing by the ignition is stopped at step 228. Such monitoring continues through the last of the programmed break-in periods, represented by TN and the corresponding revolution limits LN and over revolution limits ON. When the final break-in period TN has expired, the engine control system disengages and allows the engine to operate in normal operating mode. In normal operating mode, there may be no speed limits on the engine or an ongoing rev limit, depending on the engine and the application. However, should there be a need to reset the revolutions limits, such as may occur if the engine is rebuilt for example, new break-in periods and corresponding engine rev limits and over-revolution limits may be re-input, as shown in
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
