Electric Linear Actuator Locking Mechanism for Disk Brake
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Solution Overview
Problem
Existing electric linear motion actuators for disk brake systems are large in size, unbalanced in weight, and inefficient in energy usage, as they require continuous motor energization for parking, leading to energy waste and potential brake instability.
Innovation Solution
An electric linear motion actuator with a reduction gear mechanism, a locking mechanism that selectively locks and unlocks the rotor shaft, and a pin-driving actuator to engage and disengage the locking mechanism, allowing the motor to be deactivated during parking, thus saving energy and maintaining brake stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a locking mechanism is mounted around the rotor to enable parking brake function, then the brake system can maintain parking brake capability without continuous motor energization, but the brake system becomes large in diameter and may interfere with the wheel
Solution Approach 1:
The locking mechanism is merged with the reduction gear mechanism by utilizing the gear structure itself as part of the locking system. The locking pin engages with teeth on the gear, combining the gear's rotational function with the locking function, thereby eliminating the need for a separate locking mechanism around the rotor and reducing overall diameter.
Solution Approach 2:
The gear in the reduction gear mechanism serves multiple functions: it provides mechanical advantage for force multiplication and simultaneously serves as the locking structure when the locking pin engages with its teeth. This multi-functionality eliminates the need for dedicated separate components for each function, reducing overall system size.
2Use of energy by moving object
If a locking mechanism is mounted around the rotor, then the parking brake function is achieved, but the weight of the electric motor increases causing weight imbalance and brake squeak
Solution Approach 1:
The locking mechanism components are merged with existing structural elements of the reduction gear mechanism. The locking pin is integrated into the actuator assembly, and the engagement teeth are formed on the gear itself, distributing weight across multiple existing components rather than adding concentrated weight around the rotor.
Solution Approach 2:
The locking mechanism is extracted from the rotor assembly and relocated to the reduction gear mechanism. This separation removes the source of weight imbalance from the rotating mass of the motor, preventing the destabilizing effects and brake squeak while maintaining the parking brake function.
3Reliability
If a rigid protective cover is added to protect the locking mechanism module, then the mechanism is protected against flying stones, but the overall size of the brake system increases
Solution Approach 1:
The protective cover is merged with the existing housing structure of the reduction gear mechanism. The housing serves dual purposes as both the structural enclosure for the gear mechanism and the protective barrier against flying stones, eliminating the need for an additional separate protective cover and associated volume.
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 provides a compact, balanced, and energy-efficient electric linear motion actuator that maintains necessary braking force without continuous motor energization, reducing size and weight imbalances, and stabilizing the braking operation.
Implementation Method 1
the planetary rollers revolve around the rotary shaft while rotating about their respective axes due to contact friction between the planetary rollers and the rotary shaft
Implementation Method 2
A helical rib is formed on the radially inner surface of the outer ring member which is engaged in helical grooves or circumferential grooves formed on the radially outer surfaces of the respective planetary rollers
Implementation Method 3
a locking pin movable toward and away from the engaging portions and configured to be brought into engagement with any one of the engaging portions when moved toward the engaging portions, thereby locking the gears of the reduction gear mechanism
Implementation Method 4
a reduction gear mechanism including an output gear having a center axis for reducing a rotation of the rotor shaft of the electric motor and outputting the thus reduced rotation at the output gear
Data Source
AI summary
A disk brake system includes a disk, brake pads, and a linear motion actuator including an electric motor, a rotary shaft coupled to the motor through a reduction gear mechanism, planetary rollers formed with helical grooves in their outer surfaces, and an outer ring member having a helical rib engaged in the helical grooves. The outer ring is coupled to one of the brake pads. When the rotary shaft is rotated by the motor, the outer ring member is moved axially through the planetary rollers, and the brake pads are pressed against the disk. The linear motion actuator further includes a locking mechanism including engaging holes formed in an intermediate gear of the reduction gear mechanism at equal intervals, a locking pin, and a linear solenoid for moving the locking pin until the pin engages in one of the engaging holes, thus locking the motor.