Rotation Transmission Switching for EV Back-EMF and Shock Control
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Solution Overview
Problem
The drive unit for electric automobiles, as described in JP H09-226394 (A), faces issues when the electric motor is stopped, causing excessive reverse electromotive voltage and complicating the structure and control of the clutch, leading to an unpleasant driving experience due to potential shocks and complexity in torque transmission management.
Innovation Solution
A rotation transmission state switching device is introduced, comprising a clutch device and a restriction device, which includes a braking mechanism and engaging elements to control torque transmission between the electric motor and drive wheels, allowing for simplified configuration and reduced complexity by enabling or preventing rotation based on the motor's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a clutch is provided between the electric motor and drive wheels to separate them when the motor is stopped, then the reverse electromotive voltage problem is solved, but the structure and control become complicated
Solution Approach 1:
The patent combines the clutch device and restriction device into a single integrated transmission state switching device. The clutch device (with engaging elements) and restriction device (braking mechanism) work together as one unified system to manage torque transmission, eliminating the need for separate control mechanisms and reducing overall structural complexity.
Solution Approach 2:
The transmission state switching device serves multiple functions: it acts as both a clutch (to disconnect torque transmission) and a restriction device (to control rotation), while also managing the reverse electromotive voltage issue. This multi-functional design reduces the number of separate components needed.
2Duration of action of stationary object
If the electric motor and drive wheels remain rotating during clutch switching, then continuous operation is maintained, but the switching control becomes complex
Solution Approach 1:
The restriction device automatically activates when the clutch engaging elements are engaged, using the existing rotational motion of the drive wheels to engage the braking mechanism. The system leverages the ongoing rotation to control the engagement process without requiring external actuators or complex control systems, simplifying the switching control.
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
The solution provides a simplified structure for the rotation transmission state switching device, reducing manufacturing costs and enhancing the driving experience by effectively managing torque transmission and preventing unwanted shocks, thus improving the overall efficiency and comfort of electric vehicle operation.
Implementation Method 1
a braking device provided between a fixed portion and the first rotating member, and switching between a state in which rotation of the first rotating member with respect to the fixed portion is allowed and a state in which rotation of the first rotating member with respect to the fixed portion is prevented
Implementation Method 2
When the electric motor is electrically energized to rotate an output shaft of the electric motor, rotation torque of the output shaft is increased by the speed-reduction mechanism
Data Source
AI summary
The rotation transmission state switching device comprises a clutch device comprising a first rotating member having a first-rotating-member-side engaging portion, a second rotating member having a second-rotating-member-side engaging portion, a third rotating member having a third-rotating-member-side engaging portion; and an engaging element having an engaging-element-side first engaging portion engaging with the first-rotating-member-side engaging portion, an engaging-element-side second engaging portion engaging with the second-rotating-member-side engaging portion, and an engaging-element-side third engaging portion engaging with the third-rotating-member-side engaging portion; and a restriction device configured to switch between allowing and restricting rotation of the first rotating member, allowing or preventing torque transmission between the second rotating member and the third rotating member.