Hybrid Vehicle Start Control Device Downshift Torque Management
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Solution Overview
Problem
Existing control devices face challenges in starting an internal combustion engine while a downshift is being performed in an electric drive state, as the rotating electrical machine may not have sufficient torque to output both starting torque and inertia torque, leading to a shortage of output torque and potential disruption of the downshift operation.
Innovation Solution
A control device that delays the start control of the internal combustion engine until the downshift is completed, ensuring the rotating electrical machine only needs to output inertia torque, thereby allowing the downshift operation to proceed without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control to start the internal combustion engine is performed in parallel with downshift control in the electric drive state, then the engine can be started quickly, but the rotating electrical machine experiences torque shortage and downshift operation is disrupted
Solution Approach 1:
The control device determines whether to perform start control before downshift control based on the current drive state. By performing start control in advance when the vehicle is in engine drive state or hybrid drive state (before downshift is needed), the engine is started while the rotating electrical machine does not need to simultaneously provide inertia torque for downshift, avoiding torque shortage and ensuring reliable downshift operation.
2Productivity
If the rotating electrical machine outputs both starting torque and inertia torque simultaneously, then the engine can be started during downshift, but the total torque requirement exceeds maximum available torque
Solution Approach 1:
The control device performs start control in advance when the vehicle is in engine drive state or hybrid drive state, before downshift control is activated. This timing ensures that the rotating electrical machine only needs to provide starting torque without simultaneously providing inertia torque for downshift, keeping the total torque requirement within the maximum available torque capability.
Solution Approach 2:
The control device segments the torque requirements by separating start control and downshift control into different time periods. Start control is performed when downshift is not yet required, and downshift control is performed after engine start is complete or in progress, avoiding the need to simultaneously satisfy both torque demands.
3Reliability
If the control device waits for downshift completion before performing start control, then torque shortage is avoided, but the engine start time is delayed
Solution Approach 1:
The control device performs start control in advance when the vehicle is in engine drive state or hybrid drive state, before downshift control is activated. This early execution of start control eliminates the need to wait for downshift completion, as the engine is already started or in the process of starting when downshift is initiated, thus avoiding both torque shortage and unnecessary delays.
Data Source
AI summary
A control device that includes an electronic control unit that is configured to, in a case where a request to start the internal combustion engine is made while a downshift for changing a speed ratio of the speed change device so that the speed ratio after shifting is higher than the speed ratio before shifting is being performed in the electric drive state, perform the first start control after the downshift is completed.