Internal-combustion engines – Igniters – Incandescent
Reexamination Certificate
1999-05-10
2001-05-08
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Igniters
Incandescent
Reexamination Certificate
active
06227157
ABSTRACT:
TECHNICAL FIELD
This invention relates to glow plug systems for internal combustion engines, and particularly to power sources for glow plugs and operating methods for glow plugs.
BACKGROUND ART
Glow plugs have been used to help initiate combustion in diesel engines. At one time, glow plugs, if used at all, were included just to minimize cold starting problems. Other uses were limited by concerns about the operating life of the glow plugs. Glow plug life was improved by making them with durable ceramic material such as silicon nitride. However, such materials are subject to an ion migration characteristic that can also limit operating life. An option to increase lifetime and allow more frequent operation than just cold starting was recognized to be applying alternating current (AC) to the glow plugs, in contrast to direct current (DC) power sources, as disclosed in U.S. Pat. No. 5,724,932, Mar. 10, 1998, and U.S. Pat. No. 5,809,957, Sep. 22, 1998. The patents disclose glow plug systems with AC power sources that include an alternator dependent on engine operation, such as one driven by a hydraulic pump system operated from the engine power train.
The above mentioned patents also are representative of art relating to controllers for modifying power applied to glow plugs according to certain conditions throughout operation of the engine. The controllers can comprise programmable microprocessors utilizing sensors and electronic signal technology of a general nature like that of widely used engine control systems, sometimes referred to as engine control modules (ECMs).
By way of further background, various different diesel engine fuel systems are known. They include some in which fuel is directly injected into the engine cylinders, without premixing with air in a manifold. In some advanced systems, the fuel is directly injected at or near the end of the compression stroke at pressures up to a maximum that is in excess of 20,000 psi. One type of direct injection system, referred to as a hydraulically actuated electronic unit injection (HEUI) fuel system creates the needed pressure hydraulically by a high pressure oil pump driven by the engine, so upon starting the engine is cold-cranked to get the pump pressure to a proper level. General background on such systems is contained in an article by M. Osenga,
Diesel Progress
, August 1998, pp. 82, 84, and 86.
Another aspect of current diesel technology is the interest in a capability of operating on different fuels besides common diesel fuel. Different fuels have different combustion characteristics that have been addressed in various ways, such as those described in a paper by R. L. Miller, et al., titled “Development of a Heavy-Duty, Flexible Fuel (Methanol-Diesel) Engine System”, ASME, ICE-Vol. 27-3, Book No. 1011C, 1996, pp. 47-55.
SUMMARY OF THE INVENTION
The invention, in one aspect, provides an AC power source for glow plugs without requiring an electromechanical alternator and related elements driven by the engine.
A static (i.e., comprising solid state or other non-mechanical elements) power converter is provided for converting DC power, e.g. from a battery, to AC power. The static power converter, independent of engine operation, develops an AC output that is governed by a controller, such as one including a microprocessor, responsive to any of a variety of inputs to control the duty cycle of the converter and, thus to control the glow plug temperature.
Having a glow plug power source independent of the immediate engine operation opens up a wide range of available operating methods to enable smooth, reliable, and efficient starting and running.
Among the systems provided by the invention is one in which glow plug resistance, related to its temperature, is monitored by sensing glow plug voltage and current and determining in the controller if the resistance satisfies a pre-set range of operating conditions. A transformer can be provided to modify the AC voltage produced by the converter, if desired.
Operating methods provided by the invention include sensing, or calculating from other sensed parameters, engine temperature as well as glow plug temperature. A desired glow plug temperature can be maintained substantially continuously during and after starting including applying power to glow plugs when the engine has cooled due to light loading (e.g., coasting down hill). That helps insure a smooth continuous efficient combustion and a smooth transition when the load increases.
Also, utilizing this invention can improve cold starting operation. During a cold starting event, the controller can sense, while the engine is cranking, both the glow plug temperature and the pressure of the oil that actuates direct fuel injection. The controller can be programmed to allow fuel injection when the oil pressure has reached a high enough level for proper fuel injection and when the glow plug temperature is high enough to ensure fuel combustion. This will reduce white smoke emissions (emissions containing unburned fuel).
The improved glow plug systems and methods of the invention avoid the need for an alternator system or other engine dependent power source and they allow operating glow plugs sufficiently for smooth, efficient fuel combustion while the glow plugs get a moderate, or optimum, power that achieves relatively long operating lives. The glow plug systems of the invention can be advantageously used in a variety of diesel engines and with any of a variety of fuels by tailoring the glow plug system to a particular type of engine, fuel system and fuel composition, including systems with changes in fuel composition.
These and other aspects of the present invention will become more apparent from the following description.
REFERENCES:
patent: 4307689 (1981-12-01), Raeske et al.
patent: 4359643 (1982-11-01), Tada et al.
patent: 4399781 (1983-08-01), Tsukasaki
patent: 4483284 (1984-11-01), Andreasson
patent: 4658772 (1987-04-01), Auth et al.
patent: 4710681 (1987-12-01), Zivkovich
patent: 4820957 (1989-04-01), Zivkovich
patent: 5144922 (1992-09-01), Kong
patent: 5287831 (1994-02-01), Andersen et al.
patent: 5367994 (1994-11-01), Hinkle
patent: 5413072 (1995-05-01), Anderson et al.
patent: 5568801 (1996-10-01), Paterson et al.
patent: 5570666 (1996-11-01), Rymut et al.
patent: 5724932 (1998-03-01), Antone
patent: 5809957 (1998-09-01), Antone et al.
M. Osenga, “Diesel Progress”, Aug. 1998, pp. 82, 84, and 86.
R. L. Miller, et al., Development of a Heavy-Duty, Flexible Fuel (Methanol-Diesel) . . . , ASME, ICE-vol. 27-3,Book No. 1011C, 1996, 47-55.
Baumgartner Kenneth A.
Caruthers Michael A.
Gallmeyer Christopher F.
Miller Robert L.
Suda Kenneth J.
Caterpillar Inc.
Telfer Gordon H.
Vo Hieu T.
Yuen Henry C.
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