Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
1999-04-26
2001-05-01
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
Reexamination Certificate
active
06223723
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a control system for an engine of a small watercraft, such as a personal watercraft, and more particularly to an engine ignition control system for such a watercraft.
2. Description of the Related Art
Internal combustion engines commonly include a spark advance system to control the time of initiating combustion in response to engine running conditions. The optimum time of spark plug firing for a given running condition enhances engine performance.
Optimum spark timing for an engine depends upon a variety of factors and primarily upon the load on the engine and the engine speed. Some spark advance systems also vary spark timing when sensing engine acceleration. Many types of conventional engine ignition systems include a spark advance mechanism that interrelates with the throttle valve of the engine so as to adjust spark timing in response to throttle valve position. The throttle valve position is directly related to the engine load. In some cases, the spark advance mechanisms are mechanical and include a linkage system that directly interconnects a throttle mechanism of the engine and the spark advance mechanism. U.S. Pat. No. 5,653,208 discloses an example of such a mechanical ignition control system. More advanced engines often employ electronic control systems that employ sensors to determine the running condition of the engine, and produce a firing signal to time the firing of the spark plugs in accordance with an ignition timing map stored in the memory of the control system. U.S. Pat. No. 5,775,297 discloses an example of an electronic ignition control system. In such a system, ignition timing varies upon whether rapid acceleration from idle to a high engine speed is detected.
SUMMARY OF THE INVENTION
The present invention involves the recognition that the optimum spark timing varies with acceleration rates. An ignition control system thus desirably senses engine acceleration and controls ignition timing depending upon the acceleration rate. The control system of the present invention differentiates between at least three acceleration conditions and preferably more. For instance, in one mode, the ignition control system employs differing ignition timing maps depending upon whether the acceleration is rapid, moderate, gradual or de minimis (i.e., a generally constant engine speed).
Thus, in accordance with one aspect of the present invention, a watercraft is provided including a hull defining an engine compartment and an internal combustion engine located within the engine compartment. The engine includes at least one variable-volume chamber defined by at least first and second components. One of the components is movably contained within the other component and is connected to an output shaft of the engine so as to drive the output shaft in a rotational manner as a result of combustion within the chamber. An ignition system includes an ignition element that initiates combustion of a fuel/air mixture in the chamber, and a sensory system, which is responsive to at least engine speed, provides an engine speed signal. A controller communicating with the sensory system and with the ignition system. The controller is responsive to the engine speed signal to periodically determine whether engine acceleration is in one of at least three preset ranges of acceleration and to adjust ignition timing in response to the determine acceleration range.
In one mode, the preset ranges of acceleration correspond to substantially no acceleration, in which spark timing is adjusted in accordance with a normal ignition timing map, to rapid acceleration range, in which ignition timing is advanced relative to the normal ignition timing, and to at least one intermediate acceleration range, in which through at least some range of engine speeds the ignition timing is less advanced relative to the ignition timing for the rapid acceleration range. The controller can also further quantify the intermediate acceleration range into additional ranges to correspond to gradual acceleration and moderate acceleration. By quantifying acceleration into at least three and preferably more ranges, the ignition timing can be better tailored to optimize engine performance and provide smoother acceleration, regardless of the degree of acceleration. The ride of the watercraft during accelerations consequently improves.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiment which follows.
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patent: 5722370 (1998-03-01), Koike et al.
patent: 5738073 (1998-04-01), Koike et al.
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Dolinar Andrew M.
Knobbe Martens Olson & Bear LLP
Yamaha Hatsudoki Kabushiki Kaisha
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