Kickdown Power Control Under Active Vehicle Speed Limiting
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Solution Overview
Problem
Speed limiters in motor vehicles restrict vehicle speed, making requests for increased power from the powertrain unnecessary and inefficient, leading to increased noise and reduced fuel efficiency when attempting to exceed the speed limit.
Innovation Solution
A method and apparatus that recognize the active speed limiter and compare the current vehicle speed to a predefined threshold; if above the threshold, an altered action is triggered in response to the kickdown switch activation, avoiding unnecessary power increases and allowing tailored responses based on specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the kickdown switch is activated to increase maximum power available from the powertrain, then the vehicle can be accelerated faster, but when the vehicle speed is limited by a speed limiter, this leads to additional noise and reduced fuel efficiency
Solution Approach 1:
The control device receives signals from both the kickdown switch and the speed limiter, and uses this feedback to determine whether to activate the power increase. When the speed limiter is active and the vehicle speed is close to the speed limit, the control device prevents the powertrain from increasing maximum power, thereby avoiding unnecessary fuel consumption and noise while still responding to the driver's kickdown input.
Solution Approach 2:
The system changes the operational parameters of the powertrain based on the combined state of the kickdown switch and speed limiter. When the speed limiter is active and vehicle speed approaches the speed limit, the system modifies the powertrain's maximum power parameter to prevent increase, even though the kickdown switch is activated, thus resolving the contradiction between acceleration capability and fuel efficiency.
2Power
If the kickdown switch is activated to request increased power, then the engine torque limit can be temporarily increased, but this results in additional noise when the speed limiter is active
Solution Approach 1:
The control device monitors the state of both the kickdown switch and the speed limiter simultaneously. When the speed limiter is active and the vehicle speed is close to the speed limit, the control device uses this feedback information to prevent the engine torque from increasing, thereby eliminating the source of additional noise that would otherwise be generated by the powertrain's response to the kickdown switch.
Solution Approach 2:
The system performs a preliminary check of the speed limiter status before allowing the kickdown switch to trigger a power increase. By checking the speed limiter state in advance, the system can prevent the torque increase and associated noise before it occurs, rather than allowing the noise-generating action to happen and then correcting it.
Data Source
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AI summary
A method and an apparatus for controlling driving power from a powertrain of a motor vehicle comprising a kickdown switch, wherein an activation of the kickdown switch triggers a default action of temporarily requesting an increase of a maximum power available from the powertrain, the method comprising: ‐ recognizing (101) that a speed limiter, setting an upper speed limit for the vehicle speed, is active, ‐ comparing (102) a current vehicle speed to a predefined speed threshold, which is below the upper speed limit, ‐ if the current vehicle speed is above the speed threshold and the speed limiter is active, triggering (103) an altered action in response to the activation of the kickdown switch.