Compact Power Transmission Layout With Integrated Park Lock
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Solution Overview
Problem
There is a desire for further miniaturization of power transmission devices in electric automobiles.
Innovation Solution
A power transmission device is designed with a compact configuration that includes a planetary reduction gear, differential mechanism, and park-locking mechanism, utilizing a stepped pinion gear and integrated cooling and lubrication systems to optimize space and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional planetary gear mechanism with stepped pinion gear is used, then torque transmission is achieved, but the device size is large
Solution Approach 1:
The patent implements nesting by placing the park-locking mechanism inside the planetary gear mechanism's central space. The locking pin and locking groove are positioned within the existing gear structure, allowing the locking function to be integrated without increasing overall device volume. This nested arrangement enables torque transmission while maintaining compact dimensions.
Solution Approach 2:
The patent merges the park-locking mechanism with the planetary gear mechanism into a single integrated structure. The locking pin is positioned to engage with the carrier, and the locking groove is formed on the ring gear, combining two functional systems (power transmission and locking) into one compact unit. This merging eliminates the need for separate locking components, reducing overall device size while maintaining torque transmission capability.
2Reliability
If the park-locking mechanism is added to the planetary gear system, then locking function is achieved, but torque load on locking mechanism increases
Solution Approach 1:
The patent introduces a torque reduction gear mechanism as an intermediary between the output shaft and the park-locking mechanism. This intermediate gearing system reduces the torque that reaches the locking pin and locking groove, allowing the locking function to be achieved with lower forces on the locking components themselves, thereby improving reliability without requiring oversized locking elements.
3Productivity
If multiple gear mechanisms are integrated, then power transmission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the planetary gear mechanism to serve dual purposes: power transmission and park locking. The carrier and ring gear components perform both their primary power transmission function and serve as integral parts of the locking mechanism. This universal design allows two functions to be achieved with a single mechanism structure, improving productivity while minimizing the increase in device complexity.
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 design achieves a more compact size while maintaining effective torque transmission and lubrication, enhancing the overall performance and efficiency of the power transmission system.
Implementation Method 1
a planetary reduction gear (4) that reduces the output rotation of the motor (2)
Implementation Method 2
a differential mechanism (5) that is connected downstream of the planetary reduction gear (4)
Data Source
Figure 1
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AI summary
[Problem] To reduce the size of a power transmission device. [Solution] This power transmission device has: a bearing; a differential mechanism; a case accommodating the differential mechanism; a pinion gear supported on the case; a wall part axially overlapping with the case; a plate which is disposed between the wall part and the case in the axial direction and supports the case with the bearing therebetween; and a parking pole rotatably fixed to the plate at a position axially overlapping with the plate.