Disc Brake Motor Gear Layout to Keep Parking Brake Force
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Solution Overview
Problem
Existing motor gear units for disc brake apparatuses face challenges in maintaining the braking force by the parking brake when the electric motor is not energized, due to lubricant adherence to the non-excited operation type brake.
Innovation Solution
A motor gear unit design that includes a housing with separate compartments for the electric motor, speed reduction mechanism, and non-excited operation type brake, with the non-excited operation type brake positioned above the electric motor to prevent lubricant adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the non-excited operation type brake is positioned in the gear accommodating portion, then the structure is more compact, but lubricant from the speed reduction mechanism adheres to the brake, causing failure to maintain parking brake force
Solution Approach 1:
The housing is divided into functionally independent compartments: a motor accommodating portion for the electric motor, a gear accommodating portion for the speed reduction mechanism, and a brake accommodating portion for the non-excited operation type brake. This segmentation isolates the brake from lubricant contamination while maintaining overall compactness through integrated housing design.
Solution Approach 2:
The non-excited operation type brake is extracted from the gear accommodating portion and placed in a separate brake accommodating portion. This extraction removes the brake from the harmful lubricant environment, preventing adherence and ensuring reliable parking brake force maintenance.
2Reliability
If the worm speed reduction mechanism with self-lock function is used, then the parking brake force can be maintained without additional brake, but the friction loss increases and input-output efficiency decreases
Solution Approach 1:
The patent combines two separate functions into one integrated system: the non-excited operation type brake (providing holding force) and the ordinary worm speed reduction mechanism (providing motion transmission with acceptable efficiency). This merging achieves both reliable parking brake maintenance and reduced friction loss compared to using a self-locking mechanism alone.
Solution Approach 2:
The non-excited operation type brake acts as an intermediary component that takes over the holding function, allowing the worm speed reduction mechanism to operate without the high friction requirements of self-locking. The brake mediates between the motor shaft and the load, providing holding force without compromising the efficiency of the speed reduction mechanism.
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 effectively prevents lubricant from adhering to the non-excited operation type brake, ensuring that the braking force by the parking brake is sufficiently maintained even when the electric motor is not energized.
Implementation Method 1
a non-excited operation type brake... prevents a rotation of the motor shaft during a non-energization period
Implementation Method 2
the speed reduction mechanism includes a worm connected to the first connection portion, a worm wheel meshed with the worm
Implementation Method 3
a rotary-to-linear motion conversion mechanism, disposed in the cylinder, and configured to push out the piston toward the rotor by converting a rotary motion into a linear motion
Data Source
AI summary
A motor gear unit for a disc brake apparatus is provided. A speed reduction mechanism is connected to a first connection portion of a motor shaft of an electric motor. A non-excited operation type brake is connected to a second connection portion of the motor shaft. In a state where the disc brake apparatus is attached to a vehicle body, the motor shaft is disposed so as to be orientated in an upper-lower direction, and the non-excited operation type brake is disposed above the electric motor.