Clutch Hydraulic Pressure Control to Prevent Engine Stall
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Solution Overview
Problem
In vehicles equipped with internal combustion engines and electric motors, the connection and disconnection clutch can cause the internal combustion engine to stop suddenly when engaged, especially in situations where the electric motor is not operational, due to drag torque and rotation inertia from downstream rotating elements.
Innovation Solution
A control device that performs slip control by supplying an instruction hydraulic pressure to maintain the internal combustion engine's speed above a lower limit speed, and engagement completion control by increasing hydraulic pressure to complete clutch engagement when the speed difference between the engine and electric motor is below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the connection and disconnection clutch is engaged to transmit power from the internal combustion engine to the drive wheels, then the vehicle can travel using the internal combustion engine, but the internal combustion engine may stop suddenly due to drag torque and rotation inertia from downstream rotating elements
Solution Approach 1:
The control device performs preliminary action by gradually increasing the hydraulic pressure to engage the connection and disconnection clutch in a controlled manner, and by pre-accelerating the electric motor before engagement to reduce speed difference. This prevents sudden engagement that would cause engine speed drops and potential stopping, thereby maintaining engine operation stability while enabling vehicle travel.
2Ease of operation
If the rotational torque of the internal combustion engine is increased during clutch engagement, then the engagement control can be performed, but the speed of the internal combustion engine may suddenly decrease and the engine may stop
Solution Approach 1:
The control device uses the electric motor as an intermediary to bridge the speed difference between the internal combustion engine and the downstream rotating elements during clutch engagement. By controlling the electric motor's rotation speed to match or exceed the engine speed before engagement, the mediator prevents sudden speed drops in the engine, allowing smooth engagement control while maintaining engine speed stability.
3Productivity
If the connection and disconnection clutch is gradually engaged to synchronize speeds, then the vehicle can travel with the internal combustion engine, but the engagement process takes time and the engine speed must be carefully controlled
Solution Approach 1:
The control device replaces pure mechanical engagement with a controlled hydraulic pressure system. By using a hydraulic pressure generator to gradually and precisely control the clutch engagement pressure, the system achieves smooth speed synchronization without mechanical shock, enabling vehicle travel while minimizing engagement time and avoiding engine speed instability.
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 solution prevents the internal combustion engine from stopping when the connection and disconnection clutch is engaged, ensuring continuous vehicle operation even when the electric motor is not operational.
Implementation Method 1
a hydraulic control mechanism for controlling a hydraulic pressure supplied to the connection and disconnection clutch
Implementation Method 2
the connection and disconnection clutch is engaged by supplying an instruction hydraulic pressure
Implementation Method 3
a starter for starting the internal combustion engine
Data Source
AI summary
The control device of the vehicle performs slip control for engaging the connection and disconnection clutch as an instruction hydraulic pressure for engaging the connection and disconnection clutch by the hydraulic control mechanism after the internal combustion engine is started by the starter, as an instruction hydraulic pressure for maintaining the speed of the internal combustion engine at a higher speed than a lower limit speed for avoiding the stop of the internal combustion engine. Further, the control device of the vehicle performs engagement completion control of raising an instruction hydraulic pressure for engaging the connection and disconnection clutch from an instruction hydraulic pressure in the slip control to an instruction hydraulic pressure for completing engagement of the connection and disconnection clutch when a difference between the speed of the internal combustion engine and the speed of the electric motor becomes smaller than a preset threshold value.