Electrical Parking Brake Valve Control Logic
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Solution Overview
Problem
In commercial or utility vehicles, electrical parking brake systems face safety challenges, particularly with the 'Northland Park Brake Function', where the parking brake may not be released correctly due to inadequate pressure, potentially leading to vehicle rollaway situations when the driver leaves the cab after starting the engine, as existing solutions require complex handbrake valve mechanisms and solenoid valves to manage compressed air supply.
Innovation Solution
An electrical parking brake system with a valve device that connects directly to the spring-type brake cylinder, using a pressure sensor and electronic control unit to ensure the parking brake is only released when both sufficient pressure and the driver's presence are confirmed, eliminating the need for a solenoid valve to shut off the overflow valve, and integrating safety features like seat and pedal sensors to manage the valve's states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a handbrake valve mechanism with solenoid valves is used to manage compressed air supply, then the parking brake can be controlled, but the device complexity increases and safety risks arise from improper pressure management
Solution Approach 1:
The patent extracts the safety control function from the mechanical handbrake valve system and relocates it to the electronic control unit. The ECU monitors pressure sensor signals and driver presence indicators, then electronically controls the valve device to vent compressed air only when safety conditions are met (sufficient pressure and driver present), eliminating the need for complex mechanical safety mechanisms
Solution Approach 2:
The patent replaces the mechanical handbrake valve control system with an electronic control system. Instead of using mechanical solenoid valves and overflow valves, the system uses an electronic control unit that processes electrical signals from pressure sensors and driver presence indicators to control an electrically actuable valve device, substituting mechanical safety mechanisms with electronic control logic
2Ease of operation
If the parking brake is released when pressure is insufficient, then the brake releases easily, but the vehicle may roll away causing harmful effects
Solution Approach 1:
The patent implements preliminary safety checks before allowing parking brake release. The electronic control unit requires that sufficient compressed air pressure be present in the brake system before enabling brake release, and additionally requires detection of driver presence via indicators. This preliminary verification ensures the vehicle will not roll away when the brake is released
Solution Approach 2:
The patent uses feedback from pressure sensors and driver presence indicators to control the parking brake release function. The electronic control unit continuously monitors the pressure signal from the pressure sensor and the driver presence indicator, and only allows the valve device to vent compressed air when both conditions are satisfied, creating a closed-loop safety control system
3Reliability
If a solenoid valve is added to shut off the overflow valve, then pressure control is improved, but the device complexity increases
Solution Approach 1:
The patent makes the electronic control unit multi-functional by having it perform both the driver presence detection logic and the pressure control functions. The same ECU that processes driver presence indicators also monitors pressure sensor signals and controls the valve device, eliminating the need for separate solenoid valves and overflow valves while maintaining comprehensive pressure and safety control
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 simplifies the implementation of the 'Northland Park Brake Function' by ensuring the parking brake is only released when safe conditions are met, enhancing safety by preventing unintended vehicle movement and eliminating the need for complex handbrake valve mechanisms, thereby reducing the risk of rollaway incidents.
Implementation Method 1
A pressure sensor is provided with which a compressed-air-supply-side pressure can be measured
Implementation Method 2
In a first switched state the electrically actuable valve device ventilates (aerates) the spring-type brake cylinder, and in a second switched state the valve device vents (deaerates) the spring-type actuator
Implementation Method 3
a spring-type brake cylinder which can be acted upon by compressed air
Data Source
AI summary
An electrical parking brake system and method for a commercial vehicle includes a valve device, which connects a compressed-air supply with a spring brake cylinder without an intermediate connection of a hand brake valve. The valve device aerates the spring brake cylinder in a first switching state and deaerates the spring brake cylinder in a second switching state. The system further includes a pressure sensor, which measures a pressure on the compressed air supply side, and an electronic control unit for directly or indirectly controlling the valve device, acquiring a signal supplied by the pressure sensor, and acquiring an indicator signal for the presence of an individual in a cab of the vehicle. The valve device can only be transferred to its first switching state by the control unit if the pressure on the compressed air supply side exceeds a pressure threshold value and if the presence of an individual in a cab of the vehicle is indicated.