Automotive Drum Brake Electric Wedge Locking Mechanism
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Solution Overview
Problem
Existing drum brakes for motor vehicles require substantial physical effort to activate the handbrake due to mechanical tensioning mechanisms, which can be tiring and inconvenient for users.
Innovation Solution
The drum brake system incorporates a wheel cylinder assisted by a booster to position segments with brake linings, and an electrically controlled wedge to lock the brake in place, reducing the physical effort required to engage the parking brake by using a lever and retaining spring mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical cable tensioning mechanism is used to activate the handbrake, then the brake can be engaged, but substantial physical effort is required from the user
Solution Approach 1:
The patent replaces the traditional mechanical cable tensioning system with a hybrid system combining a wheel cylinder (hydraulic/pneumatic) assisted by a booster and an electrically controlled wedge locking mechanism. The wheel cylinder with booster provides mechanical advantage to move the segments, while the electric wedge provides locking force, eliminating the need for high user force on a cable.
Solution Approach 2:
The patent introduces a lever as an intermediary between the wheel cylinder and the segment. The lever amplifies the force from the wheel cylinder and provides a pivot point that enables the segment to rotate into the braking position more easily, reducing the direct force requirement from the user.
Solution Approach 3:
The electrically controlled wedge performs preliminary action by pre-positioning and pre-loading the locking mechanism before final engagement. The wedge is electrically actuated to engage with the segment and locking arm, creating initial contact and force distribution that reduces the peak force required from the user.
2Ease of operation
If an electrically controlled wedge locking mechanism is implemented, then the physical effort to lock the brake is reduced, but the device complexity increases
Solution Approach 1:
The patent replaces the manual mechanical locking operation with an electrically controlled wedge mechanism. The wedge is actuated by an electric motor or actuator, converting electrical energy to mechanical locking force, thereby eliminating the need for high manual force while accepting increased system complexity.
Solution Approach 2:
The locking mechanism is designed to be self-servicing through the wedge geometry and spring-loaded components. Once electrically actuated, the wedge automatically engages with the locking arm and maintains the locked position through its geometric locking action, reducing the need for continuous control input from the user.
3Ease of operation
If the wheel cylinder acts through a lever on the segment, then the braking position is achieved with reduced force, but the mechanism requires additional components
Solution Approach 1:
The lever serves as a mechanical intermediary between the wheel cylinder and the segment. It provides force amplification through its pivot connection, allowing the wheel cylinder to move the segment into the braking position with reduced force requirement, while accepting the addition of the lever component to the system.
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
Enables the drum brake to be locked in a braking position with minimal force, enhancing user convenience and reducing fatigue during parking brake activation.
Implementation Method 1
a wedge which can be electrically controlled so as to implement a method in accordance with one of the preceding embodiments
Implementation Method 2
the method comprises the step of associating a retaining spring with the lever and with the segment to determine, as a function of the stiffness of the retaining spring, an action threshold of the cylinder on the segment beyond which this action causes the lever to pivot
Implementation Method 3
a drum brake for a motor vehicle comprising a wheel cylinder intended to move a segment and a lever provided with a brake lining in a braking position
Data Source
Figure 1~2
Figure 3a~4
Figure 5a~6
AI summary
The method involves controlling an action of a wheel-brake cylinder (24) on a lever (25) of a drum brake (20) for displacing a segment (23) and the lever in a braking position. The action of the cylinder on an end of the lever is continued for rotating the lever to block a connecting rod (21) in the braking position. Displacement of a wedge is electrically controlled, where the wedge maintains the rod by blocking the lever.