Microcomputer electronic control system for automatic transmission of motor vehicle
AssigneeRegie Nationale des Usines Renault
InventorsGerard Pannier, Jean C. Roumy
Life of this patent
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Abstract
An electronic system for controlling the drive ratio changes in an automatic transmission of a motor vehicle having solenoid valves for actuating the gear changes. A microcomputer selectively governs the solenoid valves through power amplifiers, in such a way that when the solenoid valves are not energized the highest drive ratio is engaged. The ratio of the power amplifiers to the corresponding output signals of the microcomputer is such that the solenoid valves are not energized when the supply voltage is zero or when the microcomputer voltage drops below the threshold value necessary for its proper operation.
Claims13
A system for controlling the drive ratio changes in a motor vehicle automatic transmission having solenoid valves for changing the drive ratio, said valves being responsive to their solenoids and the solenoids being responsive to said system, the de-energized condition of said solenoid valves corresponding to the highest drive ratio, said vehicle having a source of energizing current, said system comprising:
- power amplifiers, each connected to the solenoid of a said solenoid valve for energizing it,
- a reset circuit,
- programmed microcomputer means connected to said power amplifiers and to said source for selectively governing the supply of energizing current to said solenoids through said power amplifiers, said microcomputer means also having resetting means connected to said reset circuit for re-initializing the program of said microcomputer means whenever the supply voltage drops to zero or whenever the microcomputer supply voltage drops below the value necessary for its proper operation, so that upon re-initialization of the program of said microcomputer, said solenoid valves are in their de-energized condition, thus assuring that the transmission will then be in its highest drive ratio when the program begins running.
A system for controlling the drive ratio changes in a motor vehicle automatic transmission comprising
- solenoid valves for changing the drive ratio of said transmission,
- power amplifiers connected to and controlling said solenoid valves, the solenoids of said valves being responsive to said electronic control system, the de-energized condition of said solenoid valves corresponding to the highest drive ratio,
- a microcomputer connected to a supply voltage and having
- (a) a reset input pin,
- (b) a random access memory,
- (c) a read only memory, and
- (d) output pins connected separately to the windings of said solenoid valves through said power amplifiers, and
- an external reset circuit connected to said reset input pin for energizing that pin during a said resetting cycle starting at each come-up of said supply voltage,
- each said power amplifier having a reversing function, so that a high level on one of said output pins leads to a de-energized state of the corresponding solenoid valve,
- said microcomputer having logic means for causing said solenoid valves to effect said highest drive ratio upon starting a said resetting cycle,
- whereby after any drop below a minimum voltage value and the resultant imposition of said highest drive ratio to said automatic transmission, then when the supply voltage reaches again the minimum value necessary for normal operation of said microprocessor, said system keeps said highest ratio, due both to the normal resetting to highest level of said output pins during said resetting cycle, and the state of said logic means thereafter until the end of calculation of the appropriate said gear ratio.
Dependencies are inferred from the claim text.