Hybrid Vehicle Clutch Sequencing for Smooth Engine Start Transitions
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Solution Overview
Problem
The rapid increase in engine torque during engine start in hybrid vehicles can cause a rapid increase in rotational speed of the transmission shaft, hindering smooth transition from the first travel mode to the second travel mode, particularly in vehicles with small inertia such as motorcycles, and existing control methods are insufficient to prevent this issue.
Innovation Solution
A hybrid vehicle controller that includes a mode switching controller, clutch controller, and throttle opening degree controller to manage the transition by bringing the clutch into a half-clutch state to start the engine using transmission shaft rotation, then shifting to a stand-by state and finally an engaged state, while adjusting actuator pressure and throttle opening degree to prevent rotational speed increases and facilitate smooth mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch is merely shifted from disengaged to engaged state to start the engine, then the engine start is achieved, but the rotational speed of the transmission shaft rapidly increases, hindering smooth mode transition
Solution Approach 1:
The clutch control system dynamically adjusts the clutch engagement state through multiple intermediate states (half-clutch state with first engagement degree, second half-clutch state with second engagement degree higher than the first) rather than a simple binary engaged/disengaged transition. This dynamic progression allows the system to gradually transmit engine torque to the transmission shaft, preventing rapid speed increases and ensuring smooth mode transition while achieving reliable engine start.
2Stability of the object's composition
If the clutch is brought into half-clutch state to start the engine using transmission shaft rotation, then smooth mode transition is achieved, but the engine start process becomes more complex
Solution Approach 1:
The clutch engagement process is segmented into distinct phases: disengaged state, half-clutch state with first engagement degree, second half-clutch state with second engagement degree, and fully engaged state. Each phase has specific control parameters and duration, transforming a complex continuous control problem into manageable discrete stages that can be systematically executed and controlled.
3Loss of time
If the clutch is shifted to engaged state immediately after engine start, then the transition to second travel mode is completed, but torque fluctuations occur due to rapid engine torque increase
Solution Approach 1:
The system performs preliminary actions by first bringing the clutch to a half-clutch state to start the engine using transmission shaft rotation, then transitioning to a second half-clutch state with higher engagement degree before final engagement. This preliminary progressive engagement prepares the system for smooth torque transfer, preventing torque fluctuations when the clutch is finally shifted to the engaged state while maintaining efficient mode transition timing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for smooth and quick transition between travel modes by preventing rapid rotational speed increases and reducing torque fluctuations, thereby enhancing the stability and efficiency of engine start in hybrid vehicles.
Implementation Method 1
a clutch actuator (6) operable to bring the clutch (5) from the disengaged state to the engaged state
Implementation Method 2
an engine (2) serving as a drive source
Implementation Method 3
an electric motor (3) serving as a drive source
Data Source
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AI summary
Provided is a hybrid vehicle controller (20) that enables a hybrid vehicle (1) to smoothly achieve travel mode switching involving engine (2) start. The hybrid vehicle controller (20) includes a mode switching controller (25) configured to, in response to a predetermined mode switching request, perform mode switching control for switching from a first travel mode where an engine (2) is stopped and a drive wheel (8) is driven by drive power generated by an electric motor (3) to a second travel mode where the drive wheel (8) is driven by drive power generated by the engine (2) and drive power generated by the electric motor (3). The mode switching controller (25) includes a clutch controller (30), and the clutch controller (30) is configured to: upon receiving the mode switching request, bring a clutch (5) into a half-clutch state to start the engine (2) using rotation of a transmission shaft (4a); and upon determining that the engine (2) has started, shift the clutch (5) from the half-clutch state to a stand-by state and subsequently shift the clutch (5) to an engaged state, the stand-by state being a state which is intermediate between the half-clutch state and a disengaged state and in which the drive power of the engine (2) is not transmitted to the transmission shaft (4a).