Measuring and testing – Internal combustion engine or related engine system or... – Compression
Patent
1981-03-03
1983-11-29
Myracle, Jerry W.
Measuring and testing
Internal combustion engine or related engine system or...
Compression
731173, G01M 1500
Patent
active
044174691
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
This invention relates generally to internal combustion engines and more particularly, to apparatus for determining the actual speed and timing advance angle of such engines.
Background Art
Basic control of the operation of an internal combustion engine is accomplished by varying the amount of fuel delivered to the engine cylinders by the fuel pump and by controlling the time that the fuel in the cylinder ignites as the pistons approach top dead center on the compression stroke. In general, the amount of fuel delivered to the cylinders will control the speed of the engine while the timing of ignition will control the efficiency of fuel combustion.
In a typical four-stroke-cycle diesel engine a timing shaft is gear driven by the engine crank shaft at half engine speed, with the timing shaft being coupled to the fuel camshaft of a fuel pump by a timing mechanism so that the fuel pump will deliver fuel to half of the engine cylinders during one engine revolution and to the other half of the cylinders during the next revolution. A controllable fuel rack will vary the amount of fuel that the fuel pump delivers to the engine cylinders and the timing mechanism will vary the angular relation between the timing shaft and the fuel camshaft so that fuel is injected into the cylinders at the proper time in engine operation relative to the pistons reaching top dead center in their compression strokes.
In order to provide an electronic engine control system which will function to maintain engine performance at maximum efficiency under varying operating conditions, it is necessary to obtain precise information as to the actual engine speed and the magnitude of the timing advance angle.
Furthermore, for an engine control system to be effective, the system must have a rapid response time, with speed and timing advance angle information being updated many successive times during a single revolution of the engine.
There are a number of problems involved in providing suitable apparatus for obtaining the desired engine speed and timing advance information.
First, the apparatus should have a life which meets or exceeds engine overhaul time to prevent premature failure and loss of control. To meet this requirement, the components utilized for detection of speed and angular displacement of the fuel camshaft should be simple, rugged and non-contacting.
The presence of engine torsionals presents a significant problem in providing accurate information as to engine speed and timing advance angle. Briefly, internal combustion engines have inherent imbalances causing the instantaneous speed of the engine to vary sinusoidally during a sequential operation of the pistons, with the engine being accelerated during operation of one half of the pistons and decelerated during the successive operation of the other half of the pistons. If the engine is operating at a given average speed, and if the instantaneous engine speed is determined once for, and at the same time during, each full cycle of sinusoidal operation, each successive instantaneous speed determination will be the same as before. Likewise, if the average engine speed should vary, the instantaneous speed determination will vary directly therewith.
However, if a speed determination is made more frequently than once during a full cycle of sinusoidal operation, as is desired in the present invention, the successive instantaneous speed determinations will vary from one another even though the average engine speed remains the same. Thus, in order to obtain useful speed information many times successively during a full sinusoidal cycle of engine operation, the effect of the engine torsionals must be cancelled out so that each successive bit of information will have the same relationship to the average engine speed.
Measurements of the timing advance angle have been made by a first sensor operable to detect movement of a fixed point on the timing shaft therepast and a second sensor operable to detect movement of a fixed point on the fuel camshaft therepa
REFERENCES:
patent: 2145347 (1939-01-01), Everitt
patent: 3964443 (1976-06-01), Hartford
patent: 4205377 (1980-05-01), Oyama et al.
patent: 4323976 (1982-04-01), Radaelli et al.
Stevenson Thomas T.
Zenios Marios C.
Caterpillar Tractor Co.
Myracle Jerry W.
Noe Stephen L.
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