Relay Valve Pressure Control via 2/2-Way Valves
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Solution Overview
Problem
The existing pressure control device for vehicle brake systems has a sluggish reaction to pneumatic pressure control signals, leading to continued compressed air flow into brake cylinders during intended pressure reduction, which hampers rapid pressure adjustments necessary for brake slip control, traction control, and vehicle dynamics control.
Innovation Solution
The method involves switching the valve device to the pressure reduction position only when the working pressure at the relay valve is lower than the brake cylinder pressure, and to the pressure build-up position when the working pressure is greater, ensuring that the 2/2-way valve is switched immediately if a permissible pressure drop or build-up is detected, and otherwise after a blocking hold time due to inertia, allowing for quicker pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single relay valve is used to control brake pressure, then the device complexity is reduced and manufacturing cost is lowered, but the reaction speed to pressure control signals becomes sluggish
Solution Approach 1:
The system segments the pressure control function by introducing a 2/2-way valve for each working port that operates independently based on pressure comparison, allowing parallel decision-making and faster response without requiring multiple relay valves
Solution Approach 2:
The pressure comparison is performed in advance by the 2/2-way valves before the relay valve needs to act, so that when pressure adjustment is needed, the system is already prepared and can respond immediately without waiting for relay valve reaction
2Productivity
If the relay valve reacts slowly to pressure reduction signals, then compressed air continues to flow into the brake cylinder, but implementing rapid pressure adjustment is necessary for ABS, ASR, and ESP functions
Solution Approach 1:
The system implements feedback by continuously comparing the working pressure at the relay valve with the actual brake cylinder pressure, and only allowing pressure reduction when the working pressure is lower, preventing overshoot and ensuring rapid, accurate pressure control
Solution Approach 2:
The 2/2-way valves act as intermediaries between the relay valve and brake cylinders, providing direct pressure control path that bypasses the slow relay valve reaction, enabling immediate pressure adjustment when needed
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 approach prevents unnecessary air flow into brake cylinders during pressure reduction and enables rapid pressure adjustments, improving the responsiveness of the brake system for ABS, ASR, and ESP functions.
Implementation Method 1
due to the relatively sluggish reaction of the relay valve to pneumatic pressure control signals introduced through its control connection
Implementation Method 2
as long as the working pressure at the working connection of the relay valve assigned to the at least one brake cylinder is greater than or equal to the pressure in the brake cylinder in question
Implementation Method 3
only when the working pressure at the relevant working port of the relay valve is lower than the pressure in the relevant brake cylinder is the 2/2-way valve assigned to the relevant brake cylinder switched to the open position
Data Source
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AI summary
The invention relates to a method for controlling a pressure control device (1) of a pressure-medium brake system of a vehicle for controlling brake pressures in brake cylinders (3, 4) of wheels of an axle individually for each wheel. The pressure control device contains a relay valve (5). According to the invention, in order to compensate the response sluggishness of the relay valve (5), shut-off valves (11, 12) connected between the relay valve (5) and the brake cylinders (3, 4) are not switched into a passage position until there is a permissible pressure gradient between the working pressures of the relay valve (5) and the brake pressures (p3, p4) in the brake cylinders (3, 4).