Engine Speed Display Lock-Up Clutch Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In vehicles with continuously variable transmissions, the engine rotational speed display experiences response delays during gear shifts in manual transmission mode, leading to a sense of incongruity when displaying the actual engine rotational speed, especially in power mode where a sporty response is desired.
Innovation Solution
An engine rotational speed display device that includes an engagement state determination module, a target rotational speed setting module, a rotational speed selection module, and a display limiting module, which selects and limits the rotational speed for display based on the lock-up clutch engagement state and gear shift operation, ensuring a sporty impression without incongruity by adjusting the variation in displayed rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actual engine rotational speed is displayed as it is during gear shift operation, then the display reflects the true engine state, but the needle movement shows a slight delay after the gear shift operation which gives a sense of incongruity to the driver
Solution Approach 1:
The system performs preliminary action by predicting the future engine rotational speed based on the operation state of the continuously variable transmission and the gear shift operation. This prediction is made in advance of the actual speed change, allowing the needle to move proactively rather than reactively, thus eliminating the perceived delay while maintaining accuracy through continuous correction as the actual speed is measured.
2Speed
If the target turbine rotational speed is used for display when lock-up clutch is engaged, then the response is quick and sporty, but the deviation between needle movement and actual engine rotational speed increases which may give sense of incongruity to the driver
Solution Approach 1:
The system uses an intermediary approach by introducing a predicted engine rotational speed that serves as a mediator between the actual engine rotational speed and the target turbine rotational speed. This predicted value incorporates both the current actual speed and the anticipated target speed based on transmission operation state, providing a smooth transition that maintains both responsiveness and accuracy without directly switching between actual and target values.
3Stability of the object's composition
If the determination period is set to be long at low rotation, then the rotational speed display is stable, but the responsiveness to quick change in engine rotational speed at high rotation is reduced
Solution Approach 1:
The system applies dynamics by making the determination period variable rather than fixed. The determination period is dynamically adjusted based on the operation state of the continuously variable transmission and the detected gear shift operation. This allows the system to use longer periods for stability when needed and shorter periods for responsiveness when gear shifts occur, optimizing both stability and responsiveness across different operating conditions.
Data Source
AI summary
An engine rotational speed display device includes: an engagement state determination module that determines an engagement state of a lock-up clutch; a target rotational speed setting module that sets a target turbine rotational speed according to a selected gear stage; a rotational speed for display selection unit that selects an engine rotational speed as a rotational speed for display when the lock-up clutch is not engaged and selects the target turbine rotational speed as the rotational speed for display when the lock-up clutch is engaged; a time measuring module that measures an elapsed time since a gear shift operation is received; and a rotational speed for display limiting module that limits a variation in the rotational speed for display per unit of time according to the elapsed time when the target turbine rotational speed is selected as the rotational speed for display.