Hybrid Vehicle Clutch Engagement Control for Shock-Free Mode Switching
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Solution Overview
Problem
Conventional hybrid vehicles experience vehicle shock when switching from electric vehicle mode to engine mode due to torque differences between the engine and motor, which can cause discomfort and compromise engine startup response.
Innovation Solution
A method of controlling the hybrid vehicle by temporarily reducing the engaging torque of the friction engagement element between the engine and motor during engine startup, allowing the engine speed to synchronize with the motor speed before fully engaging, thereby reducing torque differences and minimizing vehicle shock while maintaining engine startup responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch is controlled to fully transmit torque between engine and motor during engine startup, then the engine startup response is improved, but a large vehicle shock occurs due to torque difference between engine and motor
Solution Approach 1:
The clutch engagement torque is dynamically adjusted during the engine startup process. The control device temporarily reduces the engaging torque of the clutch when the engine speed approaches the motor rotational speed, then raises it to fully engaged state after synchronization. This dynamic adjustment suppresses vehicle shock while maintaining startup response.
Solution Approach 2:
The engaging torque parameter of the clutch is temporarily changed (reduced) during the critical synchronization phase, then restored to normal after the engine speed coincides with motor rotational speed. This parameter change eliminates the torque difference shock while preserving the ability to fully transmit torque when needed.
2Object-affected harmful factors
If the clutch engaging torque is reduced to suppress vehicle shock, then the comfort is improved, but the engine startup response is deteriorated
Solution Approach 1:
The clutch engaging torque is periodically adjusted during the engine startup sequence: initially raised to ensure rapid startup response, then temporarily reduced when synchronization is approached to suppress shock, and finally raised again to fully engaged state. This periodic adjustment resolves the contradiction between shock suppression and startup response.
Solution Approach 2:
The control device preliminarily raises the engaging torque before engine startup to ensure rapid response, then temporarily reduces it at the critical moment when engine speed approaches motor speed to prevent shock. This preliminary and subsequent adjustment sequence optimizes both startup response and comfort.
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
Effectively suppresses vehicle shock during mode switching by compensating torque differences through temporary torque reduction, ensuring smooth engine startup and reduced discomfort for passengers.
Implementation Method 1
a friction engagement element (clutch) which switches between transmission and interception of torque between the engine and the motor
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method of controlling a hybrid vehicle including an engine, a motor, and a friction engagement element provided between the engine and the motor so as to be engageable and disengageable, is provided. An engine startup control for starting the engine stopped is performed to switch a traveling mode. The method includes raising an engine speed by cranking of the motor, while transiting the friction engagement element in a disengaged state to an engaged state, when the engine startup control is started, temporarily reducing an engaging torque of the friction engagement element, after the engine speed is raised by the cranking of the motor and before the engine speed coincides with a motor rotational speed, and raising the engaging torque to set the friction engagement element to a fully engaged state, after the temporarily reducing the engaging torque and the engine speed coincides with the motor rotational speed.