Fluid Parking Brake Actuator Without Springs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vehicle braking systems with spring-actuated/fluid released parking brake actuators face issues such as unintended actuation due to fluid pressure loss, high maintenance costs, and safety risks due to heavy springs that corrode and fatigue over time, leading to potential immobilization of vehicles in undesirable locations.
Innovation Solution
A braking system that applies and releases the parking brake using fluid control without mechanical springs, utilizing a single fluid control conduit and a relay valve system to maintain brake application during fluid pressure loss, featuring a diaphragm and pushrod mechanism with a clutch to prevent release, allowing selective release and reducing the need for constant fluid pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring-actuated parking brake actuators are used, then the parking brake can be applied with mechanical force, but the actuator becomes heavy and requires constant fluid pressure to maintain release position
Solution Approach 1:
The patent removes the heavy mechanical spring from the actuator design. Instead of using a spring to apply the parking brake, the system uses fluid pressure applied to a diaphragm to move a pushrod that applies the brake. This extraction of the spring component directly reduces actuator weight while maintaining braking capability through fluid pressure actuation.
Solution Approach 2:
The patent employs fluid pressure (pneumatics) to actuate the parking brake mechanism. A diaphragm responds to fluid pressure changes, converting pneumatic energy into mechanical motion of the pushrod. This pneumatic actuation system replaces the mechanical spring system, achieving both weight reduction and reliable brake application through controlled fluid pressure.
2Reliability
If spring-actuated parking brake actuators are used, then the parking brake can be applied with mechanical force, but the spring corrodes and fatigues over time requiring maintenance
Solution Approach 1:
The patent replaces the mechanical spring system with a fluid-based diaphragm and pushrod system. The diaphragm responds to fluid pressure rather than relying on mechanical spring force. This substitution eliminates the spring component that is prone to corrosion and fatigue, thereby improving ease of repair and reducing maintenance requirements while maintaining reliable brake application through the fluid-actuated mechanism.
Solution Approach 2:
By using pneumatic fluid pressure to actuate the diaphragm and pushrod, the system replaces the mechanical spring with a cleaner, more maintainable fluid-based system. The diaphragm and pushrod components are less susceptible to corrosion and fatigue compared to high-stress springs, making the system easier to repair and maintain over time.
3Reliability
If fluid pressure is lost in the fluid control system, then the parking brake is automatically applied for safety, but the vehicle becomes immobilized in undesirable locations
Solution Approach 1:
The patent inverts the conventional spring-actuated system logic. Instead of using spring force to apply the brake and fluid pressure to release it, the system uses fluid pressure to apply the brake and allows spring force (or lack of opposing force) to release it. This inversion enables the parking brake to be released even when fluid pressure is lost, as the diaphragm can return to its neutral position without requiring maintained fluid pressure, thus maintaining vehicle mobility while preserving safety functionality.
Solution Approach 2:
The system dynamically responds to fluid pressure changes. The diaphragm and pushrod mechanism can transition between applied and released states based on fluid pressure conditions. When fluid pressure is lost, the system dynamically adapts by allowing the brake to release through the return spring or neutral position mechanism, enabling vehicle movement while still providing safety when needed through controlled fluid pressure application.
4Reliability
If a separate fluid control line is used to maintain parking brake application during fluid pressure loss, then the brake can be held applied, but the system complexity and cost increase
Solution Approach 1:
The patent makes the single fluid control line perform multiple functions: it controls both service brake application and parking brake application through the relay valve. The same fluid pressure line that actuates the service brake also, through the relay valve mechanism, controls parking brake application. This multi-functionality eliminates the need for a separate dedicated fluid control line for the parking brake, reducing system complexity while maintaining the capability to hold the brake applied during fluid pressure loss conditions.
Solution Approach 2:
The relay valve acts as an intermediary device that translates fluid pressure signals into appropriate brake chamber pressure levels. It mediates between the single fluid control line and the parking brake mechanism, enabling the system to maintain parking brake application during fluid pressure loss without requiring additional fluid control lines. The relay valve intermediate mechanism allows one fluid line to effectively control multiple brake functions.
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 system reduces the weight and maintenance complexity of the actuator, allows selective release of the parking brake, and prevents vehicle immobilization, enabling safer and easier movement of vehicles even with fluid leaks or ruptures, while using a conventional two-line fluid control system.
Implementation Method 1
Introduction of fluid on a second side of the service diaphragm urges the service pushrod away from a service release position towards a service apply position
Implementation Method 2
Introduction of fluid on a second side of the parking diaphragm urging the service pushrod to the service apply position
Data Source
AI summary
A braking system is provided that enables application and release of a parking brake with fluid control and that also maintains application of the brake during a loss of fluid pressure—all without using springs and using only a single fluid control conduit. The brake actuator for the system includes a housing defining service and parking chambers. A pushrod in the parking chamber is configured for movement with a diaphragm in the chamber. The parking brake is applied by introducing fluid on one side of the diaphragm. A clutch surrounds the pushrod and includes a tooth configured to engage corresponding teeth on the pushrod to hold the position of the pushrod even during a loss of fluid pressure. The clutch is rotated under fluid control to move the clutch tooth into and out of alignment with the teeth on the pushrod to hold and release the parking brake.