Rim Brake Slave Device Automatic Pad Wear Compensation
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Solution Overview
Problem
Hydraulic bicycle rim brakes require frequent manual adjustment due to pad wear, which is inconvenient for users.
Innovation Solution
A rim brake slave device with an adjustable piston and pressure chamber that automatically adjusts the rest position by changing the volume of the pressure chamber, allowing hydraulic fluid to flow in and compensate for pad wear without driver intervention, using a friction device and restoring spring for self-adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual adjustment mechanism is provided at master cylinder, then pad wear compensation is possible, but frequent rider intervention is required
Solution Approach 1:
The invention implements self-adjustment mechanism where the slave device automatically compensates for pad wear through its own components (threaded bushing, friction device, return spring) without requiring rider intervention. The system uses the braking force itself to drive the adjustment process, making the device service itself automatically.
Solution Approach 2:
The invention creates a feedback loop where the piston position, pad wear status, and braking force are continuously monitored and used to automatically adjust the rest position. The threaded bushing rotates in response to pad wear detection, and the return spring provides continuous feedback to maintain proper clearance, forming a closed-loop self-regulating system.
2Extent of automation
If automatic adjusting device is implemented, then rider intervention is eliminated, but device complexity increases
Solution Approach 1:
The return spring serves multiple functions: it provides the force to rotate the threaded bushing for adjustment, maintains the friction device in contact with the brake cylinder wall, and resets the piston to its initial position after braking. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The invention combines the adjustment mechanism and the return mechanism into a single integrated system within the slave device. The threaded bushing, friction device, and return spring work together as a unified assembly that performs both automatic adjustment and reset functions, rather than requiring separate adjustment and return mechanisms.
3Extent of automation
If friction device is used for self-adjustment, then automatic operation is achieved, but static friction must be overcome during adjustment
Solution Approach 1:
The system dynamically transitions between static and kinetic friction states. During normal operation, static friction holds the threaded bushing in place. During adjustment, the return spring overcomes static friction to rotate the bushing, then kinetic friction maintains rotation until the adjustment is complete, at which point static friction engages again to hold the new position.
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 automatic and reliable adjustment of the brake pads, reducing the need for frequent servicing and ensuring consistent braking performance.
Implementation Method 1
a return spring mechanism that forces the piston into a predefined rest position
Implementation Method 2
the adjusting device has a friction device which is arranged to be displaceable in the axial direction with respect to the brake cylinder relative to the brake cylinder and which generates static friction between the brake cylinder and the friction device
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
The invention relates to a rim brake actuator (1) for a hydraulic bicycle rim brake with a brake cylinder (10) in which a piston (20, 90) is arranged to be displaceable in the axial direction of the cylinder, a pressure chamber (5) in which hydraulic fluid is pressurized to actuate the brake and the piston (20, 90) is displaced, thereby increasing the volume of the pressure chamber (5), and an adjusting device for adjusting the rest position of the piston in the axial direction with respect to the brake cylinder (10), wherein the adjusting device (100) changes the volume of the pressure chamber (5) when adjusting the rest position of the piston in the axial direction with respect to the brake cylinder (10).