Vehicle Torque Control for Acceleration Feel
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Solution Overview
Problem
Existing vehicle systems experience poor acceleration feel due to the decrease in torque command with increasing vehicle speed, leading to inefficient engine operation and the need for high-performance power sources, which increase vehicle size and manufacturing costs.
Innovation Solution
A vehicle control method that adjusts driving power demand based on vehicle speed and accelerator pedal depression, using a first and second reduction rate to maintain optimal power output within the power source's capabilities, ensuring better acceleration feel without excess power source performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the torque command is decreased with an increase in vehicle speed to ensure constant power output, then the power output remains constant, but the acceleration feel deteriorates
Solution Approach 1:
The patent applies dynamics by making the torque command reduction rate variable rather than fixed. The control system dynamically adjusts the reduction rate based on vehicle speed conditions: using a first reduction rate at lower speeds and a second reduction rate at higher speeds. This dynamic adjustment optimizes both constant power output and acceleration feel across different operating conditions.
Solution Approach 2:
The patent changes the parameter of torque command reduction rate based on vehicle speed. By switching between different reduction rates (first reduction rate vs. second reduction rate) according to speed thresholds, the system maintains constant power output while improving acceleration feel in specific speed ranges without requiring excess power source performance.
2Ease of operation
If high-performance power sources are used to improve acceleration feel, then the acceleration feel improves, but the vehicle size and manufacturing cost increase
Solution Approach 1:
The patent changes operational parameters (torque command reduction rates) to optimize acceleration feel without hardware upgrades. By carefully controlling how torque command decreases with speed, the system achieves better acceleration perception using the existing power source capabilities, avoiding the need for larger or more powerful engines and motors.
Solution Approach 2:
The patent creates a virtual enhancement of power source performance through control strategies. Instead of physically upgrading to high-performance power sources, the system uses software-based torque management to simulate improved acceleration characteristics, effectively 'copying' the behavior of a more powerful system without the associated weight and cost penalties.
3Power
If the torque command is decreased with an increase in vehicle speed, then the power output remains constant, but the engine operation efficiency deteriorates
Solution Approach 1:
The patent makes the torque command adjustment dynamic by using different reduction rates at different speed ranges. This allows the engine to operate more efficiently at higher speeds by reducing torque command less aggressively (second reduction rate), while still maintaining constant power output, thereby improving overall energy efficiency compared to a fixed reduction rate approach.
Data Source
AI summary
A vehicle having a sun gear, a carrier, and a ring gear of a planetary gear mechanism respectively connected to a first motor, an engine, and a drive shaft and second motor. When the combination of measured accelerator opening and measured vehicle speed is in an ordinary acceleration area, the vehicle sets a torque demand to decrease with an increase in measured vehicle speed at a specific reduction rate that ensures substantially constant output power to the drive shaft corresponding to the accelerator opening. When the combination of the measured accelerator opening and the measured vehicle speed is in an acceleration feel improvement area, on the other hand, the vehicle sets the torque demand to an extent of or below a maximum allowable value of the torque demand to decrease with an increase in measured vehicle speed at a lower reduction rate than the specific reduction rate.