Education and demonstration – Vehicle movement or traffic accident or condition
Patent
1991-11-08
1994-06-07
Apley, Richard J.
Education and demonstration
Vehicle movement or traffic accident or condition
434219, 731172, 36442403, 36443104, 340517, 123480, G09B 1914
Patent
active
053184491
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a computerised diagnostic system for internal combustion engines. In particular, the invention is directed to a method of, an apparatus for, computer aided diagnosis of electronically fuel injected (EFI) internal combustion engines.
BACKGROUND ART
EFI engines in automobiles are commonly controlled by an on-board computer, typically a microprocessor-based device, which controls the timing and duration of the fuel injection in response to operational parameters sensed by a number of sensors on the engine, e.g. temperature, engine speed, throttle position, air flow, etc. These operational parameters can be measured many times per second so that the engine is continually operated at optimum efficiency.
Many microprocessor or micro-computer based control circuits for EFI engines are programmed to accept measured values of sensed operational parameters only when such values fall within a predetermined range e.g. to avoid responding to spurious signals or to avoid acting on faulty measurements. If the value of an operational parameter as measured by a particular sensor is outside the predetermined range, the sensor may be judged by the computer control system to have failed (whether this is, in fact, correct or not), and the actual output signal of the sensor may be replaced by a standard value (as described, for example, in U.S. Pat. No. 4,780,826) . The use of a default value enables the engine to keep operating despite the failure of a sensor. However, although the engine will still operate, it will not perform as efficiently as it should. Since the fault in the engine may be masked by the default value inserted by the computerised electronic control system, it IS difficult, if not impossible, for mechanics to locate and correct the fault using conventional tools.
Complex and expensive diagnostic equipment is PG,3 normally required to locate the fault. Such equipment is often computer-based, requiring a computer device manufactured specifically for that particular application. The use of such complex and specialized diagnostic equipment and the need for trained technicians result in increased costs for motor vehicle repair.
It is the object of the present invention to provide apparatus for computer-aided diagnosis of EFI engines which is within the economic and technical reach of most motor mechanics.
It is a further object of the invention to provide a method of computer-aided diagnosis of EFI engines wherein a diagnostic computer program includes tutorial information to enable such diagnosis to be performed by most motor mechanics.
SUMMARY OF THE INVENTION
In one broad form, the present invention provides apparatus for diagnosing an internal combustion engine, the apparatus comprising computer means having an associated display; input means for connection to the engine under test; and an interface device operatively connected between the computer means and the input means; wherein the interface device comprises:
multiple mode measurement means connected to the input means, the measurement means being responsive to control data received from the computer means to switch to a selected measurement mode,
analog-to-digital converter means for converting a measured value of a selected operational parameter to digital form, and
output means for outputting the digitized measured
value to the computer means; comparison of the measured value with a predetermined operating range and to display the result of such diagnostic comparison.
In the event that the measured value of the operational parameter is outside the predetermined operating range, the computer means is preferably programmed to provide tutorial or similar information to assist the operator in locating and rectifying the possible fault. This procedure is repeated sequentially for all selected operational parameters.
Typically, the engine is an EFI engine and the operational parameters to be tested include battery voltage, ignition pulse, starter signal, throttle position sensor, air temperature sensor, air flow meter, coolant
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patent: 4267569 (1981-05-01), Baumann et al.
patent: 4375672 (1983-03-01), Kato et al.
patent: 4470016 (1984-08-01), Palmer
patent: 4532593 (1985-07-01), Mouri et al.
patent: 4747301 (1988-05-01), Bellanger
patent: 4821217 (1989-04-01), Jackson et al.
patent: 4975846 (1990-12-01), Abe et al.
Andrewes Carl D.
McLeish Gary I.
Schoell Edwin T.
Apley Richard J.
Cheng Joe H.
Electra International Pty. Ltd.
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