Crash Test Carriage Pressure Control for Accurate Simulation
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Solution Overview
Problem
Conventional test devices for simulating motor vehicle crashes face challenges in accurately and reproducibly simulating deceleration forces due to the need for high-flow rate and quick-reacting hydraulic valves, leading to costly calibration processes and reduced simulation accuracy.
Innovation Solution
The implementation of a test device with measuring pickups to sense pressures in the piston-side and piston-rod regions of the drive cylinder, coupled with a control device that adjusts hydraulic fluid flow to maintain a predefined acceleration force, utilizing quickly reacting control valves such as 2-edge or 1-edge valve designs to achieve precise acceleration profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydraulic valves are used to control the drive cylinder, then the system can achieve basic acceleration control, but the simulation accuracy and reproducibility deteriorate due to the inability to respond quickly enough to the high acceleration requirements
Solution Approach 1:
The patent changes the control parameter from direct force control to pressure difference control. By measuring and controlling the difference between piston-side pressure and piston-rod-side pressure, the system achieves more precise and responsive control of the acceleration force, improving simulation accuracy while maintaining compatibility with standard hydraulic valve response times.
Solution Approach 2:
The patent implements a feedback control mechanism where measuring pickups continuously monitor the pressures in both cylinder regions, and the control device adjusts the hydraulic fluid distribution based on the measured pressure difference to maintain the desired acceleration profile. This closed-loop control improves reproducibility and compensates for valve response limitations.
2Reliability
If high-flow rate and quick-reacting hydraulic valves are used to achieve accurate deceleration simulation, then the simulation accuracy improves, but the device complexity and cost increase significantly
Solution Approach 1:
The patent introduces pressure measurement and control as an intermediary mechanism between the hydraulic valve and the acceleration output. By measuring pressures in both cylinder regions and controlling their difference, the system achieves accurate deceleration simulation using standard hydraulic valves rather than requiring specialized high-performance valves, thereby reducing device complexity and cost.
Solution Approach 2:
The patent replaces direct mechanical force control with hydraulic pressure control. By using fluid pressure as the control medium and measuring/controlling pressure differences rather than direct forces, the system achieves more precise control with simpler components, avoiding the need for complex high-speed mechanical valve systems.
3Reliability
If multiple calibration attempts are carried out to adapt the hydraulic valve to the real deceleration curve, then the simulation accuracy can be achieved, but the time consumption and productivity decrease
Solution Approach 1:
The patent performs preliminary action by pre-defining the desired acceleration force values and using them to directly control the hydraulic fluid quantity distribution. The control device is configured to set the hydraulic fluid quantity to be fed in or discharged per time unit based on the pre-defined acceleration profile, eliminating the need for repeated calibration attempts and significantly improving setup efficiency.
Solution Approach 2:
The patent changes from empirical calibration to calculated control by using the relationship between pressure difference and acceleration force. By controlling the pressure difference between the two cylinder regions according to pre-defined acceleration requirements, the system achieves accurate deceleration simulation without time-consuming iterative calibration, improving productivity while maintaining accuracy.
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 enhances the reproducibility and accuracy of crash simulations by allowing precise control of acceleration forces, reducing the number of calibration iterations and improving the consistency of test results without wear, thereby improving the simulation's reliability and efficiency.
Implementation Method 1
a first measuring pickup (126) for sensing a first pressure (P1) which acts in a piston-side region (128) of the drive cylinder (122), and a second measuring pickup (127) for sensing a second pressure (P2) which acts in a piston-rod-side region (129) of the drive cylinder (122), wherein the control device (150) is configured to set a quantity of hydraulic fluid which is fed into the piston-side region (128) of the drive cylinder (122) per time unit, in such a way that a difference between the first pressure (P1) and the second pressure (P2) assumes a value which corresponds to an acceleration force
Implementation Method 2
the control device (150) is configured to set the quantity of hydraulic fluid which is fed into the piston-side region (128) of the drive cylinder (122) per time unit, in such a way that the difference between the first pressure (P1) and the second pressure (P2) assumes a value which corresponds to an acceleration force which is transmitted to the carriage arrangement (110)
Data Source
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AI summary
The invention relates to a method for operating a test device (100) and to a test device (100) for simulating motor vehicle crashes, wherein the test device (100) has a carriage arrangement (110) which is arranged so as to be displaceable along a rail arrangement; a test setup which is arranged on the carriage arrangement (110) and has at least one motor vehicle component to be tested; and an acceleration unit (120) by means of which a force can be transmitted to the carriage arrangement (110) in order to accelerate the carriage arrangement (110). The acceleration unit (120) has a hydraulic drive cylinder (122) with a piston (123) and a piston rod (121) which is connected to the carriage arrangement (110). In order to ensure that a simulation of accident situations can be improved in a way which is easy to implement but nevertheless reproducible, according to the invention, at least one measuring pickup (126, 127) is provided for sensing a pressure (P1, P2) which acts in the piston-side region (128) and/or in the piston-rod-side region (129) of the drive cylinder (122), and further that a control device (150) is provided which is configured to set a quantity of hydraulic fluid which is fed into the piston-side region (128) of the drive cylinder (122), per time unit, as a function of the pressure sensed in the drive cylinder (122), and/or which is fed into the piston-rod-side region (129) of the drive cylinder (122), or discharged therefrom, per time unit, as a function of the pressure sensed in the drive cylinder (122), in such a way that an acceleration force which is transmitted to the carriage arrangement (110) assumes a value which is defined or can be defined in advance.