Vehicle Tachometer Display Control for Acceleration Response
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Solution Overview
Problem
In vehicles with automatic transmissions and continuously variable transmissions, the delayed response of the tachometer display during acceleration can lead to an unsatisfactory visually-sensible acceleration feeling for drivers, as the actual engine rotation changes do not provide immediate feedback.
Innovation Solution
A control apparatus that determines when the torque converter is in a lock-up state and the vehicle is accelerating, and displays a calculated 'acting number of rotations' on the tachometer, with a rate of change greater than the actual engine rotations, simulating a stepped shift for improved responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the tachometer displays the actual number of rotations of the engine, then the display reflects the true engine state, but the response is delayed during acceleration in vehicles with continuously variable transmissions
Solution Approach 1:
The patent creates a virtual copy of the tachometer display called the 'acting number of rotations' that mimics the behavior of traditional stepped automatic transmissions. This virtual display copies the essential characteristics of desired tachometer response (immediate reaction to acceleration requests) while being independent of the actual continuous rotation changes in CVT vehicles, thereby resolving the contradiction between accuracy and response speed.
Solution Approach 2:
The patent changes the parameter being displayed from the actual engine rotation number to a calculated 'acting number of rotations' that is derived from the target input rotation number. This parameter transformation allows the display to reflect desired acceleration behavior rather than actual physical state, improving response speed while maintaining relevance to driver expectations.
2Measurement precision
If the tachometer displays actual engine rotations continuously, then the display is always accurate, but the driver cannot perceive stepped shift characteristics in a continuously variable transmission
Solution Approach 1:
The patent makes the tachometer display dynamic by switching between displaying actual rotations and acting rotations based on vehicle state. The system dynamically adjusts the display characteristics to match driving conditions and transmission state, enabling the same physical display to adapt to different transmission modes (CVT continuous operation vs. simulated stepped shifts).
Solution Approach 2:
The patent transforms the display parameter from a direct measurement of engine rotation to a calculated value that can simulate different transmission characteristics. This parameter change enables the display to adapt to various driving scenarios and transmission modes, providing versatility while maintaining accuracy when needed.
3Speed
If the tachometer response is made more responsive during acceleration, then the driver gets better visual feedback, but the display may become disconnected from the actual engine state
Solution Approach 1:
The patent implements a feedback mechanism where the determination unit continuously monitors actual vehicle state (acceleration requests, transmission ratio changes) and uses this information to control when and how the acting number of rotations is displayed. This feedback loop ensures the virtual display remains synchronized with actual engine behavior when appropriate, preventing complete disconnection from reality while providing enhanced responsiveness.
Solution Approach 2:
The patent applies partial action by displaying the acting number of rotations only during specific conditions (acceleration requests in CVT vehicles) rather than continuously. This selective application provides enhanced responsiveness when needed while maintaining accuracy during normal operation, avoiding excessive disconnection from actual engine state.
Data Source
AI summary
The control apparatus for a vehicle includes a determination unit that determines whether or not a start condition is established, the start condition including when a torque converter is in a lockup state, and when the vehicle is in an accelerating state; and a display control unit that causes an acting number of rotations to be displayed on a tachometer instead of an actual number of rotations when it is determined by the determination unit that the start condition is established. The display control unit calculates the acting number of rotations based on a target value of an input number of rotations of a continuously variable transmission, and varies the acting number of rotations with a rate of change having an absolute value that is greater than an absolute value of a rate of change of the actual number of rotations upon an abrupt change in the target value.