Railway Vibration Damping Device Pump Speed Control
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Solution Overview
Problem
Existing vibration damping devices for railway vehicles experience hunting and excessive thrust when the temperature of the hydraulic fluid is low, leading to instability and aggravated vibration due to high kinematic viscosity, which increases pressure loss and deviates control commands from intended thrust.
Innovation Solution
The vibration damping device employs a controller to adjust the rotational speed of the pump based on the temperature of the hydraulic fluid, reducing the rotational speed when kinematic viscosity exceeds 50 mm^2/s to maintain stable thrust and prevent hunting, using a hydraulic fluid with viscosity ranging from 7 mm^2/s to 50 mm^2/s to ensure effective damping and actuation within a temperature range of -20°C to 60°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pump is driven at constant rotational speed, then the actuator can exert thrust, but when hydraulic fluid temperature is low and kinematic viscosity is high, pressure loss increases causing excessive thrust and hunting
Solution Approach 1:
The pump rotational speed is made variable instead of constant. The control device adjusts the pump's rotational speed based on hydraulic fluid temperature and kinematic viscosity conditions, allowing the system to adapt to changing viscosity conditions and prevent excessive thrust and hunting while maintaining effective damping when viscosity is high
Solution Approach 2:
The system changes the operational parameters of the pump based on hydraulic fluid conditions. When kinematic viscosity exceeds the threshold, the pump speed is reduced to compensate for increased pressure loss, thereby maintaining stable thrust output and preventing control instability
2Reliability
If the pump rotational speed is reduced when kinematic viscosity is high, then pressure loss is compensated and thrust becomes stable, but the system complexity increases
Solution Approach 1:
The control device continuously monitors the kinematic viscosity of the hydraulic fluid and adjusts the pump rotational speed accordingly. This feedback mechanism ensures that the pump speed is optimized based on real-time viscosity conditions, maintaining stable thrust while preventing hunting and control instability
Solution Approach 2:
The system replaces complex mechanical viscosity compensation mechanisms with an electronic control system that monitors kinematic viscosity and adjusts pump speed electronically. This substitution simplifies the overall system while achieving the desired thrust stability
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 prevents hunting and ensures stable thrust, effectively suppressing vibrations in railway vehicles by adjusting the pump speed according to hydraulic fluid temperature, maintaining optimal viscosity for both actuation and damping functions across varying temperatures.
Implementation Method 1
a pump (12) for supplying a hydraulic fluid into the rod-side chamber (5)
Implementation Method 2
when a temperature of the hydraulic fluid in the circuit is low, a kinematic viscosity of the hydraulic fluid is high
Implementation Method 3
a variable relief valve (22) provided in a middle of the discharge passage (21) and capable of varying a valve opening pressure
Implementation Method 4
obtain the thrust that suppresses vibration of the body using a hydraulic pressure
Data Source
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AI summary
A vibration damping device for railway vehicle includes an actuator and a damper circuit that causes the actuator to function as a damper. The actuator includes a cylinder coupled to a truck of a railway vehicle, a piston, a rod coupled to the piston and a body, a rod-side chamber and a piston-side chamber inside the cylinder, a first on-off valve for a first passage that communicates between a rod-side chamber and a piston-side chamber, a second on-off valve for a second passage that communicates between the piston-side chamber and a tank, and a pump that supplies a hydraulic fluid into the rod-side chamber. The hydraulic fluid has such kinematic viscosity-temperature characteristics that a kinematic viscosity of the hydraulic fluid ranges from 7 mm2/s to 50 mm2/s in a temperature range of from 20°C to 60°C.