Vehicle Drive Control Device for Consistent Shift Feel
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Solution Overview
Problem
Drivers experience a difference in shift feel when a vehicle's speed ratio is changed stepwise by a stepped shift device and steplessly by a differential gear unit, leading to an unpleasant impression due to varying rotational speed changes and shift shocks.
Innovation Solution
A control device that coordinates the shift device and differential gear unit to change the speed ratio by adjusting the shift speed established by the shift device and the rotational speeds of the differential gear unit's elements, ensuring that the controlled parameters, such as rotational speed and torque, undergo similar changes during both shift device and differential gear shift control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the speed ratio is changed stepwise by the differential gear unit that can steplessly change the speed ratio, then the shift feel difference becomes noticeable to the driver, but the complexity of the control system increases
Solution Approach 1:
The control device uses feedback control to monitor the rotational speed of the internal combustion engine and the torque transmitted through the shift device. Based on this feedback, the controller adjusts the output torques of the first and second rotating electrical machines to reproduce the same controlled parameter changes whether the speed ratio is changed by the stepped shift device or the differential gear unit, ensuring consistent shift feel.
Solution Approach 2:
The control device is designed to handle both shift device shift control and differential gear shift control through a single unified control system. The controller can manage speed ratio changes from either the stepped shift device or the differential gear unit by controlling the rotating electrical machines, making the system versatile in handling different shift control modes while maintaining consistent shift feel.
2Adaptability or versatility
If the speed ratio is changed by combining stepped shift device and differential gear unit, then the speed ratio can be adjusted flexibly, but the driver perceives different shift feels between the two methods
Solution Approach 1:
The control device changes the output torques of the first and second rotating electrical machines as control parameters to ensure that the controlled parameters (rotational speed of internal combustion engine and torque transmitted to output member) undergo similar changes regardless of whether the speed ratio is changed by the stepped shift device or the differential gear unit. This parameter control approach maintains consistent shift feel while allowing flexible speed ratio adjustment.
3Ease of operation
If the controlled parameters are made to change similarly during both shift device and differential gear shift control, then the shift feel consistency is improved, but the control complexity increases
Solution Approach 1:
The control system uses the existing rotational speed and torque sensors already present in the vehicle drive system to obtain feedback signals. The controller processes these signals and automatically adjusts the output torques of the rotating electrical machines without requiring additional complex measurement systems, allowing the system to self-regulate for consistent shift feel using available resources.
Data Source
AI summary
A control device that includes an electronic control unit that is programmed to: perform shift device shift control in order to change a speed ratio, which is a ratio of a rotational speed of the internal combustion engine to a rotational speed of the output member, by changing at least the shift speed that is established by the shift device; and perform differential gear shift control in in order to change the speed ratio by changing rotational speeds of the first rotary element and the second rotary element of the differential gear unit without changing the shift speed that is established by the shift device.