Vehicle Tachometer Display Control During Upshift
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Solution Overview
Problem
Conventional display control devices for vehicles with automatic transmissions fail to provide a sense of engine performance to the limit for drivers during upshifts, as the meter-displayed rotational speed does not reach the upper limit, causing a sense of incongruity due to mismatched decrease timings between actual and displayed engine rotational speeds.
Innovation Solution
A display control device with an electronic control unit that sets a maximum display rotational speed higher than the actual engine speed, especially during upshifts, and adjusts this value based on vehicle acceleration and engine rotational speed gradient to ensure the display rotational speed feels the engine performance limit and matches the actual rotational speed decrease timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the meter displays the actual engine rotational speed during upshift, then the display is accurate and reliable, but the driver cannot feel the engine performance to the limit and experiences a sense of incongruity when the displayed speed does not reach the upper limit
Solution Approach 1:
The system performs preliminary action by setting a predetermined maximum display rotational speed before the actual engine speed reaches it. During upshift, the display shows this predetermined maximum value instead of the actual speed, allowing the driver to perceive engine performance to the limit while the actual speed is being reduced due to the upshift. This resolves the contradiction by preparing the display behavior in advance to maintain driver engagement despite the upcoming speed reduction.
Solution Approach 2:
The system changes the display parameter from showing actual engine rotational speed to showing a predetermined maximum display rotational speed during specific conditions (upshift). This parameter change allows the display to maintain a sense of high performance (at the maximum value) even when the actual physical parameter (engine speed) is decreasing, thereby resolving the contradiction between accuracy and driver perception.
2Reliability
If rotational speed decrease is started before the engine reaches upper limit speed to protect the engine, then engine protection is ensured, but the driver cannot feel use of engine performance to the limit
Solution Approach 1:
The system applies preliminary action by establishing a predetermined maximum display rotational speed that is set before the actual engine speed reaches the upper limit. During upshift, even though the actual speed is reduced for engine protection, the display maintains this predetermined maximum value, allowing the driver to perceive that the engine is operating at its limit while the actual protection mechanism is active.
Solution Approach 2:
The display system acts as an intermediary between the actual engine state and the driver's perception. It mediates by showing a predetermined maximum value that represents engine performance capability rather than the instantaneous actual speed, thereby protecting the engine while maintaining driver confidence in engine performance.
3Ease of operation
If the maximum display rotational speed is set higher than actual speed during upshift, then the driver feels engine performance to the limit, but there may be deviation between displayed and actual speed
Solution Approach 1:
The system applies local quality by making the display behavior context-dependent. The predetermined maximum display rotational speed is used specifically during upshift conditions, while other display modes may show actual speed. This localized application resolves the contradiction by limiting the discrepancy to specific situations where engine protection is active, maintaining accuracy in other contexts.
Solution Approach 2:
The system dynamically changes the display parameter based on operating conditions. During upshift, it switches from displaying actual speed to displaying a predetermined maximum value. This conditional parameter change resolves the contradiction by allowing inaccuracy only when necessary for driver perception during specific protective operations.
Data Source
AI summary
A target reaching rotational speed set during a torque phase is set to a value higher than an actual engine rotational speed, the value being higher as one of a vehicle acceleration and an engine rotational speed gradient is larger. That is, as the acceleration is steeper, the target reaching rotational speed is set to a value closer to an upper limit rotational speed or rotational speeds proximate thereto. Thus, a display rotational speed displayed on a tachometer at the end of the torque phase becomes high rotational speed. Accordingly, there is provided a display control device for a vehicle that enables a driver to feel the use of engine performance to the limit.