Hybrid Vehicle Clutch Torque Gradient Control
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Solution Overview
Problem
Conventional hybrid vehicle control systems experience a delay in acceleration due to the limited transmitted torque capacity of the second clutch during engine start, leading to reduced vehicle performance.
Innovation Solution
A hybrid vehicle control apparatus that includes an engine start control part to manage the slipping state of the second clutch by setting its torque capacity below a set limit and gradually increasing it using a first and second increase gradient, allowing the first clutch to engage and the second clutch to reach full engagement, thereby delaying the torque limit and reducing acceleration delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmitted torque capacity of the second clutch is limited to the cranking-condition torque limit value to maintain the second clutch in slip state, then the engine start control is stable, but the vehicle acceleration becomes zero and acceleration is delayed
Solution Approach 1:
The patent applies dynamics by making the torque capacity of the second clutch variable rather than fixed. The torque capacity is dynamically adjusted based on the operational phase: during the cranking operation, it is limited to maintain slip state stability, but during the subsequent engagement operation, it is increased to enable acceleration. This temporal dynamic adjustment resolves the contradiction between maintaining stable slip state and achieving vehicle acceleration.
Solution Approach 2:
The patent applies preliminary action by first establishing the slip state with limited torque capacity to ensure stable engine start, and then preparing for the next phase by increasing the torque capacity. The control device preliminarily sets the torque capacity to the limit value during cranking, and after engine start is confirmed, it prepares for acceleration by increasing the torque capacity in the engagement operation, thus resolving the acceleration delay issue.
2Speed
If the transmitted torque capacity of the second clutch is increased rapidly to improve vehicle acceleration, then the acceleration performance improves, but the second clutch cannot be maintained in slip state and engine start control becomes unstable
Solution Approach 1:
The patent applies dynamics by implementing phase-based torque capacity adjustment. During the cranking operation phase, the torque capacity is dynamically limited to maintain slip state stability. During the engagement operation phase after engine start, the torque capacity is dynamically increased to improve acceleration. This temporal differentiation resolves the contradiction between acceleration performance and control stability.
Solution Approach 2:
The patent applies segmentation by dividing the engine start control into two distinct operations: cranking operation and engagement operation. Each operation has different torque capacity requirements. The cranking operation uses limited torque capacity for stability, while the engagement operation uses increased torque capacity for acceleration. This segmentation allows each phase to optimize for its specific requirement without compromising the other.
Data Source
AI summary
A hybrid vehicle control device includes an engine start control unit which, at engine start, starts slipping a second clutch, sets a first clutch to a slip-engaged state, and sets the second clutch transmission torque capacity to less than or equal to a set torque limit value during cranking, maintains the slip state and cranks the engine, and when the engine is put in a drive state, controls the first clutch and the second clutch towards a fully engaged state. The engine start control unit is provided with a second clutch torque increase gradient control unit which, when performing cranking processing, performs first increasing processing for increasing the second clutch transmission torque capacity command value at a first increase gradient, and second increasing processing for increasing said value at a second increase gradient more gradual that the first increase gradient.