Variable Clearance Braking System for Earthmoving Equipment
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Solution Overview
Problem
In braking systems for machines like earthmoving or load handling equipment, large running clearances between discs are required at high speeds to reduce parasitic losses, but this increases hydraulic fluid demand, necessitating greater manual brake operation, which is undesirable.
Innovation Solution
A braking system with a charging valve that adjusts the clearance between brake applying and brake discs by controlling the flow of pressurized hydraulic fluid, reducing clearance for normal operation and increasing it at high speeds to minimize parasitic losses, using a conventional or modified master valve and electrically operated charging valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large running clearance is provided between the discs when the brake is not applied, then parasitic losses are reduced, but greater movements of the foot pedal or other manual brake operating member are required
Solution Approach 1:
The patent applies dynamics by making the running clearance between brake discs variable rather than fixed. The system automatically adjusts the clearance based on operating conditions: maintaining small clearance during normal operation for ease of braking, and increasing clearance at high speeds to reduce parasitic losses. This is achieved through a slave piston that responds to hydraulic pressure changes, dynamically optimizing the balance between energy efficiency and operational ease.
2Loss of energy
If large running clearances are provided between the discs, then parasitic drag losses are reduced, but more hydraulic fluid is required from the master valve to apply the brake
Solution Approach 1:
The patent introduces a slave piston as an intermediary device between the master valve and the brake discs. This slave piston accumulates hydraulic fluid and uses its own movement to adjust the running clearance independently of the master valve. By this intermediary mechanism, the system can increase clearance to reduce parasitic drag without requiring additional hydraulic fluid from the master valve, thus resolving the contradiction between energy loss reduction and hydraulic fluid consumption.
3Device complexity
If a conventional master valve is used, then the system is simple, but it cannot dynamically adjust running clearance based on operating conditions
Solution Approach 1:
The patent enhances the conventional master valve system by adding a slave piston that performs multiple functions: it acts as a hydraulic accumulator, a clearance adjustment mechanism, and an automatic control element. This multi-functional addition allows the simple conventional master valve to gain dynamic adaptability, automatically adjusting running clearance based on operating conditions without requiring a completely new complex valve design.
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 solution allows for effective braking with minimal manual effort during normal operation while reducing parasitic losses at high speeds by dynamically adjusting the disc clearance, thus optimizing energy efficiency and operational ease.
Implementation Method 1
A braking system with a charging valve that adjusts the clearance between brake applying and brake discs by controlling the flow of pressurized hydraulic fluid
Implementation Method 2
the operating piston, when the charging valve is deactivated, being moveable in the operating cylinder to allow hydraulic fluid to pass from the transmission line thus to permit the brake actuator to move in a second direction
Implementation Method 3
The brake fluid which moves the brake applying member is typically supplied by a master valve, commonly referred to as a master cylinder, which includes a piston assembly which is manually moveable, e.g. by a brake pedal, to provide pressurised brake fluid to the brake actuator
Data Source
AI summary
A braking system includes a brake actuator which is moveable by pressurised hydraulic fluid fed to the actuator along a transmission line, in a first direction, to move a brake applying member to apply a braking force to a member to be braked, a master valve including an operating piston which upon operation of a brake operating member, moves in an operating cylinder, to direct the hydraulic fluid under pressure to the transmission line to apply the brake, the system further including a charging valve, the charging valve being operable when activated, to deliver a predetermined volume of pressurised hydraulic fluid to the master valve to move the brake applying member in the first direction towards the member to be braked to reduce the clearance between them, and the operating piston, when the charging valve is deactivated, being moveable in the operating cylinder to allow hydraulic fluid to pass from the transmission line thus to permit the brake actuator to move in a second direction opposite to the first direction to increase the running clearance between the brake applying member and the member to be braked.