Vehicle Control Device Torque Response in Reduced-Cylinder Operation
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Solution Overview
Problem
In cylinder deactivation engines, the longer combustion interval during reduced-cylinder operation leads to delayed response in torque reduction and cornering force increase, causing discomfort during vehicle turns, especially in low rotation speed regions where combustion frequency is lower.
Innovation Solution
A vehicle control device that permits vehicle posture control when the engine rotation speed is above a first predetermined value and allows reduced-cylinder operation when the rotation speed exceeds a second predetermined value, limiting reduced-cylinder operation in the low rotation speed region to improve response and prevent torque shock during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If reduced-cylinder operation is performed during vehicle posture control in low rotation speed region, then fuel economy is improved, but the response of torque reduction deteriorates due to longer combustion interval
Solution Approach 1:
The system dynamically switches between reduced-cylinder operation and all-cylinder operation based on the vehicle posture control state and engine rotation speed. When vehicle posture control is active in low rotation speed region, the system transitions from reduced-cylinder operation to all-cylinder operation to ensure rapid torque reduction response, thereby resolving the contradiction between fuel economy and response speed.
2Quantity of substance
If reduced-cylinder operation is performed, then the number of combustions per unit time decreases, but the combustion interval becomes longer causing delayed torque response
Solution Approach 1:
The system prepares by monitoring the vehicle posture control state and engine rotation speed in advance. When vehicle posture control becomes active in low rotation speed region, the system proactively switches from reduced-cylinder operation to all-cylinder operation before the torque response delay occurs, ensuring timely cornering force increase and preventing the time delay problem.
3Speed
If all-cylinder operation is performed during vehicle posture control, then torque reduction response is improved, but fuel economy deteriorates
Solution Approach 1:
The system changes the operational parameter of the engine by switching between reduced-cylinder operation and all-cylinder operation based on specific conditions (vehicle posture control state and engine rotation speed). This parameter change allows the system to optimize both fuel economy and torque response performance by selecting the appropriate operation mode for each driving condition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the degradation of vehicle posture control response in low rotation speed regions by executing reduced-cylinder operation during vehicle posture control, ensuring timely torque reduction and cornering force increase, thus enhancing driving stability and comfort.
Implementation Method 1
reduced-cylinder operation that stops combustion in some of the cylinders and all-cylinder operation that performs combustion in all of the cylinders
Data Source
AI summary
A vehicle control device includes an engine 10 capable of switching between reduced-cylinder operation and all-cylinder operation, an engine control mechanism that controls an engine torque, and a PCM 50 that executes vehicle posture control for generating vehicle deceleration by controlling the engine control mechanism to reduce the engine torque upon satisfaction of a condition that a vehicle is travelling and a steering angle-related value related to a steering angle of a steering device increases. In addition, this PCM 50 permits the execution of the vehicle posture control when an engine rotation speed is more than or equal to a first rotation speed Ne1 and permits the execution of the reduced-cylinder operation of the engine 10 when the engine rotation speed is more than or equal to a second rotation speed Ne2 that is more than the first rotation speed Ne1.