Servo Motor Hydraulic Control for Injection Molding Energy Efficiency
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Solution Overview
Problem
Existing hydraulic source control systems for injection molding machines face challenges in energy efficiency due to constant flow rate issues with three-phase induction motors and instability in fluid pressure control, leading to increased energy loss and complexity in control systems.
Innovation Solution
A hydraulic source control device using a servo motor with a motor section and amplifier, where a control device computes and outputs torque limitation values to maintain constant torque, reducing fluid pressure and flow rate, and includes a backflow prevention mechanism to stabilize fluid supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a three-phase induction motor is used to drive the hydraulic pump, then the motor structure is simple and cost is low, but the rotational speed is constant causing excessive working fluid discharge and energy loss
Solution Approach 1:
The patent applies dynamics by transitioning from a constant-speed induction motor to a variable-speed servo motor system. The servo motor dynamically adjusts rotational speed based on actual working fluid discharge requirements, enabling the hydraulic pump to operate at optimal speeds and reduce energy loss from excessive fluid discharge through relief valves.
Solution Approach 2:
The patent changes the operational parameters by controlling the servo motor to vary rotational speed according to demand. The control device adjusts motor speed parameters in real-time to match the actual flow rate requirements of the hydraulic system, preventing the constant high-speed operation that causes energy waste.
2Reliability
If feedback control using a fluid pressure sensor is implemented, then fluid pressure stability is improved, but the number of parts increases and control complexity increases
Solution Approach 1:
The patent replaces the mechanical feedback control system (fluid pressure sensor and feedback control circuit) with a simplified control approach. Instead of using pressure feedback, the system uses the servo motor's inherent ability to precisely control rotational speed and flow rate, substituting mechanical pressure sensing with electronic motor control.
Solution Approach 2:
The servo motor system performs self-regulation by automatically adjusting its rotational speed based on commanded values from the control device. The system monitors its own operational state through the servo control loop and makes necessary adjustments without requiring external pressure sensors or complex feedback mechanisms.
3Loss of energy
If the servo motor rotational speed is reduced to reduce working fluid discharge, then energy loss is reduced, but fluid pressure becomes unstable and control oscillates
Solution Approach 1:
The patent implements feedback control through the servo motor system, where the control device continuously monitors the motor's rotational speed and adjusts it to maintain stability. The servo control loop provides real-time feedback on motor performance, enabling the system to stabilize fluid pressure while operating at reduced speeds that minimize energy loss from excessive fluid discharge.
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 enables energy savings without increasing the number of parts or complicating control, stabilizes fluid pressure, and prevents backflow, resulting in efficient operation of injection molding apparatuses.
Implementation Method 1
a servo motor (53) including a motor section that drives the hydraulic pump (42)
Data Source
AI summary
The hydraulic source control device includes an operation input device capable of inputting operation conditions regarding the driving force of a fluid pressure control element, a servo motor including a motor section that drives a hydraulic pump and an amplifier that drives the motor section, and a controller that outputs a control command to the servo motor based on an input result to the operation input device. The controller obtains the fluid pressure of a working fluid based on the operation conditions regarding the input driving force, computes the output torque of the motor section based on the relationship between the fluid pressure and the output torque that are stored in advance, and outputs the computed output torque to the amplifier as a control command of the torque limitation value of the servo motor.