Hybrid Vehicle Control Device Torque Variation
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Solution Overview
Problem
The torque upper limit value of a motor in hybrid vehicles decreases with increasing rotation speed during engine start, leading to a reduction in drive torque, as the conventional method sets the torque upper limit independently for EV mode and engine start, causing a decrease in drive torque during engine start control.
Innovation Solution
A control device for hybrid vehicles that includes an engine start control part to start the engine from EV mode by increasing the motor's rotation speed while allowing slippage of the second clutch and bringing the first clutch into slip engagement, and a drive torque upper limit setting part that sets the drive torque upper limit value based on an added motor rotation speed, preventing a decrease in drive torque during engine start.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque upper limit value of the motor is set based on the rotation speed of the motor during engine start, then the motor can be protected from excessive torque, but the drive torque decreases as the rotation speed increases
Solution Approach 1:
The patent changes the parameter used for setting the torque upper limit from the actual motor rotation speed to an added motor rotation speed (which is a lower reference value). This parameter substitution allows the torque upper limit to be maintained at a higher level during engine start, preventing the drive torque decrease that would otherwise occur as the motor rotation speed increases.
2Adaptability or versatility
If the torque upper limit value is set independently for EV mode and engine start mode, then each mode can be optimized separately, but the drive torque varies during engine start control
Solution Approach 1:
The patent applies a universal torque upper limit setting method that uses the added motor rotation speed as the basis for determining the torque upper limit in both EV mode and engine start mode. This unified approach ensures that the drive torque remains consistent across different operating modes, eliminating the torque variation that occurs when independent setting methods are used.
Data Source
AI summary
Provided is a control device for a hybrid vehicle, capable of suppressing a drive torque variation during engine start control. The hybrid vehicle has an engine (Eng) and a motor/generator (MG). The control device has: an engine start control part that performs engine start control to start the engine (Eng) from an EV mode by increasing a motor rotation speed of the motor/generator (MG), while allowing slippage of a second clutch (CL2), and bringing a first clutch (CL1) into slip engagement; and a drive torque upper limit setting part (600) that sets a drive torque upper limit value (Tdrlim) in the EV mode based on an added motor rotation speed (Nad), which is given by adding an additional rotation speed (N+) to the motor rotation speed (Nmot), as an upper limit of a drive torque transmitted to drive wheels through the second clutch CL2.