Engine brake control system for vehicle
AssigneeNissan Motor Co., Ltd.
InventorsTomohiro Fukumura, Hajime Kosaka
Life of this patent
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Abstract
A control system for controlling engine braking effect of a vehicle includes a sensor section, an actuator section and a controller section at least. The sensor section includes sensors, such as longitudinal and lateral acceleration sensors or wheel speed sensors, for determining a vehicle operating variable indicative of slipperiness of a road surface. The actuator section varies a manipulated variable, such as a throttle opening degree, an air fuel ratio or a gear ratio, of an engine and transmission system to control the engine braking torque in response to a control signal. The controller section decreases the engine braking torque by varying the manipulated variable as the road surface becomes more slippery.
Claims23
An engine brake control system in a vehicle in which fuel supply to a cylinder of an engine is cut off when a driver applies engine brake by releasing an accelerator pedal and thereby decreasing an engine throttle opening degree, the engine brake control system comprising:
- an actuator section capable of varying an engine braking torque during execution of fuel cutoff;
- and
- a controller section monitoring a degree of slipperiness of a road surface, calculating, from the degree of slipperiness, a limit engine braking torque which decreases as the degree of slipperiness increases, and decreasing the engine braking torque with increase in the degree of slipperiness by controlling the engine braking torque to a value corresponding to the limit engine braking torque by controlling the actuator.
An engine brake controlling process in a vehicle in which fuel supply to a cylinder of an engine is cut off when a driver applies engine brake by releasing an accelerator pedal and thereby decreasing an engine throttle opening degree, the engine brake controlling process comprising:
- a first step for estimating a degree of slipperiness of a road surface;
- a second step for decreasing an engine braking torque during deceleration with increase in the degree of slipperiness;
- and
- a third step for performing a fuel cutoff operation during an engine braking operation in a predetermined engine operating region:
- wherein the first step comprises a first sub-step of determining an engine speed of the engine of the vehicle, a second sub-step of producing an accelerator release detection signal when an accelerator releasing operation is detected, a third sub-step of calculating a vehicle operating variable indicative of the degree of slipperiness and a fourth sub-step of calculating a limit decelerating torque in accordance with the vehicle operating variable, and the second step comprises a first sub-step of determining a gear ratio of a transmission of the vehicle, a second sub-step of calculating a limit engine braking torque in accordance with the limit decelerating torque and the gear ratio, a third sub-step of calculating a desired value of a manipulated variable in accordance with the limit engine braking torque and the engine speed, and a fourth sub-step of producing a control signal to control the manipulated variable to the desired value, the manipulated variable being a condition of an engine and transmission system of the vehicle.
A control system in a motor vehicle, comprising:
- a sensor section sensing vehicle operating conditions and collecting information on an engine speed of the vehicle, an accelerator position of an accelerator of the vehicle, a gear ratio of a transmission of the vehicle, and a vehicle operating variable indicative of a frictional road surface condition;
- an actuator section varying a manipulated variable to control an engine braking torque of the vehicle in response to a control signal;
- and
- a controller section receiving the information from the sensor section, determining a limit engine braking torque in accordance with the vehicle operating variable and the gear ratio, producing an accelerator release detection signal when the accelerator is released, determining a desired value of the manipulated variable in accordance with the limit engine braking torque and the engine speed, and controlling the engine braking torque during deceleration by producing the control signal representing the desired value of the manipulated variable when the accelerator release detection signal is present.
Dependencies are inferred from the claim text.