Electricity: measuring and testing – Internal-combustion engine ignition system or device
Reexamination Certificate
1999-06-18
2001-04-10
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Internal-combustion engine ignition system or device
C324S537000
Reexamination Certificate
active
06215310
ABSTRACT:
BACKGROUND
The US Army, like many other military organizations, is interested in lengthening the life of its vehicles and vehicle components. Doing so not only reduces the need to purchase new equipment but also reduces the logistical effort needed to sustain vehicles in the field or in forward combat areas. A case in point is the ignition system for the Army's High Mobility Multipurpose Wheeled Vehicle, or HMMWV. Recently, the Army developed a control circuit that increases the life of glow plugs in the HMMWV's diesel engine. Very basically, the circuit operates by imposing a duty cycle on the glow plugs. The cycle controls the level and duration of electrical power sent to the glow plugs to effect engine ignition and provides for controlled delays between applications of electrical power to the plugs. In order to test glow plug life through repetitions of the duty cycle, it was necessary to develop a test mechanism that emulated the environment of the glow plugs, that allowed sensors to be easily mounted on the test apparatus, and that provided a quick, simple way to immediately detect a plug's failure to glow at the appropriate point in the duty cycle. That testing mechanism was developed and is the subject of this patent application.
The mechanism is also useful for testing diesel ignition systems on fielded vehicles generally to determine whether the system is functioning properly. The mechanism is easily built from commonly available materials and requires very little in terms of instrumentation. Also, the source of electrical power and pressurized water needed by the mechanism can be provided by the battery and water pump of an automotive vehicle. Consequently, the mechanism can be used in the field, and particularly can be used under conditions typical of those behind the lines in a combat zone.
SUMMARY
The mechanism comprises an electrical power source and a source of fluid under pressure, the fluid normally being water. The mechanism includes glow plugs receiving power from the electrical power source and a control circuit connected to the electrical power source and the plugs. As mentioned above, the control circuit governs the duty cycle during which the plugs are heated by electricity and allowed cool. The mechanism includes an elongate jacket constructed of thin walls of material conductive of heat and electricity, the jacket having a fluid inlet port at one end and having a fluid outlet port at the other end. The jacket is provided with receptacles which accept the glow plugs, the receptacles being passages that extend all the way through the jacket and seal the plugs from the fluid. The receptacles conduct heat and electricity and provide a link in the electrical path by which the glow plugs are grounded. The tips of the plugs extend out of the receptacle and beyond the jacket and these tips glow when the plugs are energized, whereby the success or failure of the plug to function during energization is immediately apparent to a human viewer. The glowing tips show that there is no break in the electrical path from the power source to the control circuit, or through lines from this circuit to the plugs or in the plugs themselves. Thus, the entire circuit of which the glow plugs are part is visually tested for electrical continuity. The testing mechanism also includes means to control the rate of flow of the fluid through the jacket, and the flow control means can be governed as a function of the jacket's temperature by means of a flow control circuit.
REFERENCES:
patent: 4862370 (1989-08-01), Arnold et al.
Petrovich Paul A.
Schmitz John J.
Stormer A. David
Kuhn David L.
Leroux E P
Metjahic Safet
Taucher Peter A.
The United States of America as represented by the Secretary of
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