Actuator Unit Vibration Suppression Neutral Position Control
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Solution Overview
Problem
Existing actuator units for railway vehicles face challenges in stabilizing vibration suppression, particularly in curved sections where noise and drift inputs lead to excessive thrust, causing the vehicle body to overshoot the neutral position and fail to converge vibrations effectively.
Innovation Solution
The actuator unit incorporates a cylinder, piston, tank, pump, and directional control valves with a variable relief valve system, allowing selective communication between chambers and the tank, and a center passage to control thrust direction and magnitude, preventing excessive pressure and thrust generation when the vehicle body passes the neutral position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator unit generates large thrust to counterbalance vehicle body acceleration detected by the acceleration sensor, then vibration suppression is improved, but the vehicle body may overshoot the neutral position and fail to converge due to noise and drift effects
Solution Approach 1:
The patent implements feedback control by detecting piston position and using this information to control the variable relief valve. The valve opening pressure is adjusted based on piston position feedback, allowing the system to reduce thrust when the piston approaches the neutral position and prevent overshooting, while maintaining effective vibration suppression during actual vibration events.
Solution Approach 2:
The variable relief valve dynamically adjusts its valve opening pressure based on piston position. As the piston approaches the neutral position, the valve opening pressure is reduced, allowing excess thrust to be released. This dynamic adjustment enables the system to adapt thrust magnitude to the current state, preventing overshoot while maintaining suppression capability.
2Measurement precision
If dual pumps and variable relief valves are used to control thrust in both directions, then thrust control precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of dual pumps and dual variable relief valves into a single pump and a single variable relief valve. The single pump alternately supplies working fluid to different chambers based on piston position, while the single variable relief valve adjusts valve opening pressure according to piston position to control thrust in both directions. This integration maintains thrust control precision while significantly reducing system complexity.
Solution Approach 2:
The single pump and single variable relief valve are designed to perform multiple functions: the pump supplies working fluid to either the first or second chamber as needed, and the variable relief valve controls thrust magnitude in both expansion and contraction directions. This multi-functionality eliminates the need for separate components for each direction, reducing complexity while maintaining control precision.
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 configuration enables stable vibration suppression by preventing thrust assistance when the vehicle body passes the neutral position, absorbing vibrations effectively and improving passenger comfort without relying on sensor outputs, and simplifies the actuator unit's configuration by eliminating the need for dual pumps and variable relief valves.
Implementation Method 1
a pump (8)
Implementation Method 2
a variable relief valve (15) provided on midway of the control passage (26), the variable relief valve (15) being configured so that the valve opening pressure can be varied, to allow the working fluid to flow from the supply passage (24) toward the tank (7) when a pressure in the supply passage (24) reaches the valve opening pressure
Implementation Method 3
The vehicle body of the railway vehicle is supported by a bogie using an air spring or the like. In a bolsterless truck, when the vehicle body swings in the lateral direction relative to the bogie, the air spring generates a reaction force for returning the vehicle body to the center.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An actuator unit includes two chambers defined in the cylinder; a supply passage allowing a working fluid discharged from the pump to be supplied to the two chambers; a discharge passage allowing the two chambers to communicate with the tank; a direction control valve configured to selectively communicate each of the two chambers with one of the pump and the tank; a control passage that branches from the supply passage on a side of the pump rather than the direction control valve so as to communicate the pump with the tank; a variable relief valve provided on the control passage, the variable relief valve opening so as to allow the working fluid to flow from the supply passage toward the tank when a pressure in the supply passage reaches the valve opening pressure; and a center passage that communicates the tank with an interior of the cylinder.