Hydraulic Drive Device Back Pressure Control Circuit
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Solution Overview
Problem
Conventional hydraulic drive devices for injection molding machines face challenges in accurately and stably controlling back pressure due to potential differences between the electrical systems of the molding machine controller and the pressure control valve, especially at low pressures, leading to errors in pressure control.
Innovation Solution
A hydraulic drive device with a pressure control valve incorporating a pressure sensor and a feedback control circuit that corrects the pressure instruction value based on the detected pressure value, using a second feedback control circuit in the molding machine controller to eliminate errors and ensure accurate pressure control, even at low pressures, and incorporating a temperature sensor to account for temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure control valve with feedback control circuit is used to control back pressure, then pressure control accuracy is improved, but measurement precision deteriorates at low pressure levels due to potential difference between controller and valve electrical systems
Solution Approach 1:
A potential difference elimination circuit is introduced as an intermediary component between the molding machine controller and the pressure control valve. This circuit actively compensates for the potential difference that arises when the controller and valve are located in different environments, thereby maintaining signal accuracy at low pressure levels where the potential difference would otherwise cause significant measurement errors.
Solution Approach 2:
The system employs a feedback control mechanism where the pressure sensor detects the actual back pressure, and this detection value is fed back to the controller. The controller compares the actual value with the target value and adjusts the pressure control valve accordingly. This closed-loop feedback ensures that measurement precision is maintained despite environmental potential differences.
2Adaptability or versatility
If the pressure control valve and molding machine controller are located away from each other in different environments, then system flexibility is improved, but measurement precision deteriorates due to potential difference between electrical systems
Solution Approach 1:
The potential difference elimination circuit serves as a mediator that allows the controller and valve to be positioned in different locations while maintaining electrical signal accuracy. This intermediary device compensates for the potential difference caused by different environmental conditions, enabling flexible system configuration without sacrificing measurement precision.
3Productivity
If feedback control circuit is integrated into pressure control valve, then device complexity is reduced and response speed is improved, but measurement precision deteriorates due to uncorrected potential difference errors
Solution Approach 1:
The potential difference elimination circuit is integrated into the feedback control system as an intermediary component. This allows the system to maintain high-speed response characteristics while simultaneously correcting for potential difference errors, thereby achieving both fast response and high measurement precision without compromising either aspect.
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 accurate and stable pressure control across various pressure levels, including low back pressures, reduces the number of pressure sensors needed, and simplifies the system configuration, while also enhancing energy efficiency and responsiveness of the hydraulic drive device.
Implementation Method 1
a pressure sensor 2 for detecting a hydraulic pressure
Implementation Method 2
an oil immersion electromagnetic solenoid plunger device that produces a mechanical output proportional to an excitation current
Implementation Method 3
a fluid control valve device that controls the pressure or the amount of fluid by being displaced by the mechanical output through a spring force
Data Source
AI summary
In a hydraulic drive device (1) for an injection molding machine (M) that has a pressure control valve (Vs) incorporating a pressure sensor (2) for detecting a hydraulic pressure and a feedback control circuit (Cs) for controlling the hydraulic pressure by feedback based on a pressure detection value (Spd) obtained from the pressure sensor (2) and a pressure instruction value (Spc) fed from a molding machine controller (3), the molding machine controller (3) includes a second feedback control circuit (Cm) for correcting the pressure instruction value (Spc) that is fed to the pressure control valve (Vs) based on the pressure detection value (Spd) fed from the pressure control valve (Vs) and the pressure instruction value (Spci) obtained from the interior of the molding machine controller (3).