Vehicle Control Unit Gear Ratio Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle control technologies do not accurately reflect a driver's intention to decelerate when switching from automatic to temporary manual mode through downshift operations, leading to imprecise gear ratio adjustments.
Innovation Solution
A vehicle control unit that adjusts gear ratios based on engine speed and vehicle speed, selecting a gear ratio that ensures engine speed is equal to or greater than a reference rotational speed set according to vehicle speed, and varying this reference speed based on road gradient and accelerator pedal operation to enable precise deceleration through engine braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gear ratio is changed to a lower gear ratio through downshift operation when switching from automatic mode to temporary manual mode, then the transmission ratio is reduced, but the engine speed becomes lower than the reference rotational speed, failing to accurately reflect driver's deceleration intention
Solution Approach 1:
The control unit changes the gear ratio parameter based on the engine speed parameter. When engine speed is below the reference rotational speed after downshift operation, the control unit adjusts the gear ratio to a lower value (higher transmission ratio) to increase engine speed, ensuring it reaches or exceeds the reference rotational speed. This dynamic parameter adjustment resolves the contradiction by automatically optimizing gear ratio selection to accurately reflect driver deceleration intention.
2Speed
If the gear ratio is set to a lower gear ratio immediately after switching to manual mode, then the transmission ratio is reduced for faster response, but the engine speed drops below the reference rotational speed, causing imprecise control
Solution Approach 1:
The control unit continuously monitors engine speed and compares it with the reference rotational speed. After downshift operation, if engine speed is detected to be below the reference value, the control unit provides feedback by adjusting the gear ratio to a lower value (higher transmission ratio) to increase engine speed back to or above the reference level. This closed-loop feedback mechanism ensures both rapid response and reliable engine speed control accuracy.
3Device complexity
If a predetermined gear ratio is selected without considering engine speed, then the gear ratio selection is simplified, but the engine speed may fall below the reference rotational speed, failing to provide appropriate engine braking
Solution Approach 1:
The control unit dynamically changes the gear ratio parameter based on real-time engine speed parameter. When engine speed falls below the reference rotational speed after downshift, the system automatically adjusts to a lower gear ratio (higher transmission ratio) to increase engine speed and provide appropriate engine braking. This parameter-based control eliminates the need for complex multi-factor selection logic while preventing harmful effects of improper gear ratio selection.
Data Source
AI summary
There is provided a vehicle control unit. The vehicle control unit provides an automatic mode that automatically determines a gear ratio in accordance with an operational status of a vehicle and a temporary manual mode that, with a driver's operation, selects any one predetermined gear ratio from among predetermined gear ratios set in advance and automatically switches a mode of operation to the automatic mode according to the operational status of the vehicle. When switching a mode of operation from the automatic mode to the temporary manual mode through a downshift operation that changes a gear ratio to a lower one in a transmission and an engine speed is lower than a reference rotational speed set in accordance with a vehicle speed, the vehicle control unit selects any one of the predetermined gear ratios such that the engine speed is equal to or more than the reference rotational speed.