Motor Transmission Unit Axial Guide for EPB Seal Protection
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Solution Overview
Problem
Conventional motor transmission units for electronic parking brake devices experience seal ring deformation due to eccentric shaft movement, leading to brake oil leakage, as the eccentric rod shakes and swings, reducing its lifespan.
Innovation Solution
A motor transmission unit comprising a case, driving member, board, rod, and push unit, where the board moves axially along the driving member without rotating, directly pushing a push unit to move a piston and contact a brake disk lining plate, eliminating rotational and swinging motion that deforms the seal ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the eccentric shaft is driven by the transmission shaft to ensure linear movement without rotation, then the electronic parking brake function is achieved, but the eccentric shaft shakes and swings during action, causing the seal ring to deform quickly and reducing its lifespan
Solution Approach 1:
The patent introduces a guide hole in the clamp and a guide boss on the push rod that fit together to form a guiding mechanism. This intermediary guiding structure constrains the push rod's movement path, preventing shaking and swinging during operation. The guide boss is restricted within the guide hole, ensuring stable linear motion without compromising the seal ring.
2Reliability
If the eccentric shaft continuously contacts the recess of the push rod to prevent rotation, then the linear movement is maintained, but the shaking and swinging action applies force to the seal ring, causing deformation and brake oil leakage
Solution Approach 1:
The guiding mechanism consisting of the guide hole and guide boss acts as an intermediary that separates the functional movement from the harmful shaking. The guide boss fits within the guide hole to provide precise linear guidance, eliminating the shaking and swinging that previously caused seal ring deformation and brake oil leakage.
3Reliability
If the push rod moves axially without rotation to directly push the lining plate, then the seal ring is protected from deformation, but the structure requires a guide mechanism to constrain the movement
Solution Approach 1:
The guiding function is segmented into two parts: the guide hole formed in the clamp and the guide boss formed on the push rod. This segmentation allows the guiding mechanism to be distributed across existing components rather than requiring a separate complex guide structure. The guide hole and guide boss work together to constrain movement while utilizing the existing structural elements of the brake assembly.
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
Prevents seal ring deformation and brake oil leakage by ensuring the push unit moves axially without rotation, thereby extending its lifespan and maintaining the brake's functionality.
Implementation Method 1
The board is threadedly mounted to the driving member and located in the passage
Data Source
AI summary
A motor transmission unit for an electronic parking brake device includes a case, a driving member, a board, a rod and a push unit. The case is slidably mounted to a cap of a clamp. The driving member is partially inserted into the case. The board is threadedly mounted to the driving member. The rod is located between inner periphery of the passage and the board. The push unit has a first end thereof contacting the first end face, and a second end of the push unit is inserted in the clamp. A portion of the second end of the push unit contacts a piston. When the driving member is driven, the board moves axially. The board is restricted by the rod and does not rotate. The board pushes the push unit axially which moves the piston to push a lining plate of the clamp to contact a brake disk.