Select-Low Valve Anti-Compound Parking Brake Control
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Solution Overview
Problem
Existing parking brake devices for motor vehicles, particularly those with trailers, face challenges in implementing an anti-compound function that prevents excessive stress on the towing vehicle's parking brake when the service brake is activated simultaneously, and in providing additional switching options without affecting the trailer brake.
Innovation Solution
A parking brake device with a control valve, relay valve, and trailer control module, where a select-low valve is used to prevent compressed air from reaching the trailer control module during the anti-compound function, and additional select-high valves allow independent control of the pneumatic braking device and trailer control module, enabling separate activation and testing functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the service brake is activated simultaneously with the parking brake, then the service brake can be applied, but excessive stress is applied to the parking brake and the trailer control module is incorrectly influenced
Solution Approach 1:
A select-low valve is introduced as an intermediary component between the relay valve and the trailer control module. This valve monitors the control line pressure and selectively blocks or allows air flow to the trailer control module based on whether the service brake is activated, thereby preventing incorrect trailer brake activation and excessive stress on the parking brake system
2Device complexity
If the parking brake device is simplified, then the construction becomes less complex, but additional switching options and anti-compound function may be compromised
Solution Approach 1:
The select-low valve serves multiple functions: it prevents incorrect trailer control module activation during service braking, enables the anti-compound function to protect the parking brake, and allows independent testing of the trailer brake system. This multi-functionality achieves versatility without proportionally increasing device complexity
3Adaptability or versatility
If the trailer control module is connected to both service brake and parking brake lines, then it can be controlled from both systems, but unwanted coupling of control inputs occurs
Solution Approach 1:
The select-low valve acts as a smart intermediary that dynamically controls the connection between the service brake line and the trailer control module. When service brake pressure is detected, the valve blocks the connection to prevent unwanted coupling. When no service brake pressure is present, the valve allows connection for normal trailer brake control operations
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 solution effectively prevents excessive stress on the towing vehicle's parking brake during simultaneous service brake activation and provides additional switching options, ensuring the trailer control module is not influenced by the service brake pressure, while allowing independent control and testing of the trailer brake system.
Implementation Method 1
the pressure present for activating the service brake switches the select-low valve in such a way that the trailer control module is not supplied with compressed air
Implementation Method 2
the relay valve being controllable by means of the control valve device and at least the pneumatic brake device being controllable by means of the relay valve
Implementation Method 3
spring-loaded brake cylinders which, in the released position, apply compressed air to a spring compression chamber and thus keep the spring tensioned
Data Source
Figure 1
AI summary
The present invention relates to a parking brake device (1) for motor vehicles, comprising at least one control valve device (20), at least one relay valve (35), at least one pneumatic brake device (42) and at least one trailer control module (46), wherein the control valve device (20) and the relay valve (36) are connected to each other by means of a connecting line (24, 34), the relay valve (36) being controllable by means of the control valve device (20) and at least the pneumatic brake device being controllable by means of the relay valve (36), wherein at least a first control line (38) of a separate service brake is connected to the relay valve (36), characterized in that a first select-low valve (48) is arranged between the relay valve (36) and the trailer control module (46).