Bicycle Hydraulic Brake Lever with Roller Cam Mechanism
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Solution Overview
Problem
Conventional bicycle hydraulic brake actuation devices require excessive lever arm travel for brake pads to engage with the rotor, leading to delayed braking response.
Innovation Solution
A hydraulic brake actuation device featuring a push rod with rollers that interact with a cam surface on the lever, allowing for a variable lever-to-piston movement ratio, enabling quicker brake pad engagement with the rotor by altering the mechanical advantage during lever movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional hydraulic brake actuation devices use a direct lever-to-piston connection, then the structure is simple, but the brake pads require excessive lever arm travel to engage with the rotor, resulting in delayed braking response
Solution Approach 1:
The patent applies the dynamics principle by implementing a variable ratio mechanism where the lever arm connects to the master piston through a linkage system that changes the mechanical advantage ratio during lever travel. This allows the system to provide higher mechanical advantage during the initial phase of lever movement to quickly close the gap between brake pads and rotor, then transition to a different ratio for sustained braking pressure, thereby reducing overall lever arm travel required for brake engagement.
Solution Approach 2:
The patent employs parameter changes by varying the mechanical advantage ratio as a function of lever arm position. The linkage system is designed so that the ratio of lever arm movement to master piston movement is not constant but changes dynamically during the braking operation, optimizing the relationship between lever travel distance and brake pad displacement to achieve faster response with reduced travel.
2Speed
If the lever arm travel is reduced for faster brake engagement, then braking response improves, but the mechanical advantage and braking force may be compromised
Solution Approach 1:
The variable ratio linkage system dynamically adjusts the mechanical advantage during lever travel. During the initial phase when the brake pads need to close the gap to the rotor, the linkage provides a higher mechanical advantage ratio that amplifies the lever arm force more significantly, enabling faster pad engagement with sufficient force. As the braking operation progresses and the desired pressure is reached, the ratio transitions to maintain adequate braking force with reduced lever travel.
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
This configuration enhances braking response by reducing the required lever travel for brake pad engagement, providing improved braking performance and responsiveness.
Implementation Method 1
The push rod includes at least one roller configured to contact to the contact surface of the lever. The contact surface is configured and arranged to move the push rod as the lever is pivoted
Implementation Method 2
Pivoting movement of the lever arm provides leverage for moving the master piston causing changes in the hydraulic pressure and movement of a slave piston in the caliper
Data Source
AI summary
A bicycle hydraulic brake actuation device includes a hydraulic master cylinder housing having a bore, a master piston and a radial seal received in the bore a push rod and a lever. The push rod is configured to move the master piston and the radial seal between a neutral position and a braking position. The lever is pivotally attached to the housing for pivotal movement between an at rest position and a brake actuation position. The lever includes a contact surface configured and arranged to move the push rod as the lever is pivoted between the at rest position and the brake actuation position. Further, the push rod includes at least one roller configured to contact to the contact surface of the lever.