Actuator Unit Transmission Mechanism for Door Lock Downsizing
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Solution Overview
Problem
Conventional actuator units for shifting a vehicle door lock device between locked and unlocked positions require a larger electric motor to resist the elasticity of a return spring, which is not desirable for downsizing and results in unnecessary operation burden.
Innovation Solution
The actuator unit allows the output shaft to rotate between two angular positions without rotating the drive gear, eliminating the need for a return spring by using a transmission mechanism that enables rotation between these positions without gear rotation and stops gear rotation when the output shaft reaches the new position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return spring is arranged to restore the worm wheel to the neutral angular position, then the drive gear can be kept in the neutral angular position, but a larger electric motor is needed to resist the elasticity of the return spring
Solution Approach 1:
The invention extracts and eliminates the return spring from the system by redesigning the transmission mechanism. The new mechanism uses a ratchet and pawl system to maintain the drive gear in the neutral angular position without requiring elastic restoration, thereby removing the need for a large motor to counteract spring elasticity.
Solution Approach 2:
The invention introduces a ratchet and pawl mechanism as an intermediary between the drive gear and the neutral position requirement. This intermediary mechanism maintains positional control through mechanical engagement rather than elastic restoration, allowing the motor to operate without continuously resisting spring force.
2Ease of operation
If the drive gear is always kept in the neutral angular position using a return spring, then the transmission mechanism can prevent extra operation burden, but the actuator unit size increases
Solution Approach 1:
The invention removes the return spring component that was causing the actuator unit to increase in size. By replacing the spring-based neutral position maintenance with a ratchet and pawl mechanism, the overall volume of the actuator unit is reduced while preserving manual operability.
3Reliability
If the electric motor continuously resists the return spring elasticity, then the worm wheel can be restored to neutral position, but energy consumption increases
Solution Approach 1:
The invention transforms the continuous energy consumption required to resist spring elasticity into periodic action. The motor only needs to overcome friction and inertia during actual position changes, while the ratchet and pawl mechanism maintains position passively without continuous energy input, significantly reducing overall energy consumption.
Data Source
AI summary
When an output shaft is positioned in a first angular position or a second angular position, the output shaft is allowed to rotate from one angular position to the other angular position without rotating a worm wheel. When the worm wheel is rotated to rotate the output shaft from one angular position to the other angular position, the rotation of the worm wheel is transmitted to the output shaft. When the output shaft is placed in the other angular position, driving-force transmission to the output shaft is released, and at the same time, rotation of the worm wheel is stopped.