Electromechanical Brake Parking Gear Locking Against Braking Force Loss
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Solution Overview
Problem
Electromechanical brakes lack self-locking capability, leading to arbitrary loss of braking force when power is cut off due to the structural nature of ball screws, which prevents stable maintenance of a parking braked state.
Innovation Solution
A brake apparatus with a parking gear and restriction unit that engages with the transmission gear, utilizing an electromagnetic force to prevent piston separation from the pad and inhibit braking force loss, even when the drive unit is released, by employing a parking drive unit, restoration unit, and stopper to restrict rotation of the parking gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a ball screw is used in the electromechanical brake to ensure quick responsiveness and high efficiency of the piston, then the piston can move quickly and efficiently, but the brake cannot perform self-locking to restrict rotation of the ball screw, causing braking force to be arbitrarily eliminated when power is cut off
Solution Approach 1:
A one-way clutch mechanism is introduced as an intermediary component between the ball screw and the piston. This clutch allows the piston to move freely during normal braking operation for quick responsiveness, but automatically locks when power is cut off to prevent arbitrary elimination of braking force, thus resolving the contradiction between speed and reliability.
Solution Approach 2:
The one-way clutch mechanism is designed to automatically engage and lock the ball screw rotation when power is cut off, preventing the repulsive force between the pad and piston from causing arbitrary elimination of braking force. This preliminary anti-action ensures the braking force is maintained during parking brake operations.
2Force
If the parking gear is made with a smaller diameter to reduce load on the restriction unit, then the load is reduced, but the gear may interfere with adjacent components such as ECU installed at the periphery
Solution Approach 1:
The parking gear is designed with a non-uniform tooth distribution pattern, having a smaller diameter for reducing load on the restriction unit, while strategically positioning the teeth to avoid interference zones where adjacent components like ECU are installed. This local quality adjustment resolves the contradiction between force reduction and avoiding harmful interference.
3Reliability
If the stopper is inserted into the parking gear to restrict rotation and maintain parking brake state, then the parking brake state is stable, but the insertion structure requires precise alignment and manufacturing
Solution Approach 1:
An insertion guide structure is provided in the parking gear that beforehand cushions and guides the stopper into the correct position. This guide structure compensates for manufacturing tolerances and ensures precise alignment during assembly, reducing the required manufacturing precision while maintaining reliable parking brake stability.
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 effectively maintains a stable parking braked state by preventing piston separation and ensuring consistent braking force, while reducing the load on the restriction unit and preventing interference with adjacent components.
Implementation Method 1
a parking drive unit configured to generate an electromagnetic force
Implementation Method 2
a restoration unit positioned between the rod and the parking drive unit, and configured to move the rod to a second direction when a supply of the electromagnetic force is discontinued
Data Source
AI summary
A brake apparatus for a vehicle may include: a drive unit configured to generate driving power; a transmission gear configured to be rotated by the driving power transmitted from the drive unit; a piston configured to move forward or rearward in conjunction with the rotation of the transmission gear and press or release a pad in a direction in which the piston moves forward or rearward; a parking gear configured to engage with the transmission gear and rotate in conjunction with the rotation of the transmission gear; and a restriction unit installed to be movable toward the parking gear and configured to restrict the rotation of the parking gear by being inserted into the parking gear during parking braking.