Hybrid Vehicle Tachometer Speed Display Control
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Solution Overview
Problem
Conventional vehicle control apparatuses for hybrid vehicles with continuously variable transmissions (CVTs) cause unnatural rotation speed displays to drivers during simulated stepwise shift modes due to variations in engine speed, leading to discomfort during acceleration.
Innovation Solution
A displayed rotation speed control apparatus that displays a target primary rotation speed as the driving source speed in the simulated stepwise shift mode, and retards the actual engine speed when switching from EV to HEV mode or continuous shift to simulated stepwise shift mode, ensuring a smoother transition and reducing unnatural feelings for the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actual engine speed is displayed in the tachometer during simulated stepwise shift mode, then the rotation speed display reflects the true engine state, but the driver experiences unnatural feeling due to sudden speed variations
Solution Approach 1:
The patent introduces a displayed engine speed that acts as an intermediary between the actual engine speed and the tachometer display. During simulated stepwise shift mode, instead of directly displaying the actual engine speed which causes unnatural fluctuations, the system displays a smoothed or interpolated speed value that mediates between the actual variations and the driver's perception, thereby maintaining measurement accuracy while improving driver comfort
Solution Approach 2:
The patent changes the parameter being displayed from the actual engine speed to a displayed engine speed that is modified according to the operating mode. During simulated stepwise shift mode, the displayed speed parameter is adjusted to reflect target primary rotation speed rather than actual speed, transforming the display parameter to eliminate unnatural fluctuations while preserving the information needed for driver awareness
2Adaptability or versatility
If the transmission gear ratio is stepwisely varied during acceleration, then the vehicle provides simulated stepwise shift feeling, but the rotation speed display becomes unnatural due to repeated gradual increase and sudden decrease of input rotation speed
Solution Approach 1:
The patent applies dynamics by making the display parameter adaptive to the operating mode. The system dynamically switches between displaying actual engine speed and displayed engine speed based on whether the vehicle is in continuous shift mode or simulated stepwise shift mode. This dynamic adaptation allows the system to maintain display stability during simulated shifts while preserving the ability to show real speed during normal operation
Solution Approach 2:
The patent uses preliminary action by pre-calculating or pre-setting the displayed engine speed based on target primary rotation speed before actual speed variations occur. During simulated stepwise shift mode, the system prepares the display value in advance to follow the target speed profile, preventing the unnatural fluctuations that would otherwise appear when the actual speed suddenly decreases during gear ratio changes
Data Source
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AI summary
In a displayed rotation speed control apparatus for a vehicle, a hybrid vehicle includes a transverse engine (2) and a motor generator (4) which are driving sources, and a belt type continuously variable transmission (6) disposed between the motor generator (4) and front wheels (10R, 10L). The hybrid vehicle has an EV mode, an HEV mode, a continuous shift mode in which a transmission gear ratio of the belt type continuously variable transmission (6) is continuously varied, and a simulated stepwise shift mode in which the belt type transmission gear ratio of the continuously variable transmission (6) is stepwisely varied. This displayed rotation speed control apparatus for the vehicle includes a display control unit (87) which is configured to produce a displayed rotation speed signal to a tachometer (102a) disposed within a vehicle interior, and which has a display mode in which a target primary rotation speed (Npri*) stepwisely set is displayed as a driving source rotation speed in the tachometer (102a) in the simulated stepwise shift mode.