Electro-hydraulic Control Arrangement for Injection Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrohydraulic control arrangements for injection molding machines require powerful and expensive servomotors for low-speed high-torque operations and involve complex precalculation of speed values, leading to energy losses and complicated sequence programming.
Innovation Solution
An electrohydraulic control arrangement with an adjustable fluid pump and a variable-speed electric drive, featuring a pressure detector and a main control circuit that adjusts speed and displacement volume based on detected fluid pressure, allowing direct specification of manipulated variables and automatic optimization for energy efficiency, low noise, and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed displacement pump is directly connected to a hydraulic consumer and actuated by a variable-speed electric servo drive, then precise control of the consumer is achieved, but a powerful and expensive servomotor is required to generate sufficient torque at low speeds
Solution Approach 1:
The control system is segmented into two independent parts: a variable displacement pump for flow control and a proportional valve for pressure control. This divides the control functions so that the electric motor only needs to drive the pump at variable speeds without requiring high torque at low speeds, while the proportional valve handles the pressure regulation that would otherwise demand high motor torque.
Solution Approach 2:
A proportional valve is introduced as an intermediary between the hydraulic pump and the hydraulic consumer. This valve acts as a mediator that controls the flow to the consumer based on pressure feedback, allowing the electric motor to operate at higher speeds with lower torque requirements while still achieving precise consumer control through the valve's flow modulation.
2Productivity
If a variable displacement pump is operated with precalculated speed values stored in a sequence control device, then the injection molding process is controlled, but the precalculation becomes complicated and energy losses occur due to reserved conveying capacity
Solution Approach 1:
A pressure sensor provides continuous feedback on the actual pressure in the hydraulic system, and this feedback signal is fed to the controller. The controller uses this real-time pressure information to dynamically adjust the displacement volume of the pump via the proportional valve, eliminating the need for complex precalculation of speed values and allowing adaptive optimization of energy consumption during operation.
Solution Approach 2:
The system transitions from static precalculated speed values to dynamic real-time control. The displacement volume of the pump is continuously adjusted based on actual pressure conditions detected during operation, allowing the system to adapt to varying load conditions and eliminate the need for conservative speed reservations that cause energy losses.
3Speed
If the speed of an electric motor is set downstream depending on the deflection of a swash plate with fast dynamic response, then rapid response is achieved, but energy efficiency is reduced due to high speed operation below pressure threshold
Solution Approach 1:
The pressure sensor provides continuous feedback on actual system pressure, enabling the controller to make real-time decisions about pump operation. This feedback allows the system to maintain fast dynamic response by quickly adjusting displacement volume when pressure changes occur, while simultaneously optimizing energy efficiency by reducing or stopping pump operation when high pressure is not required, eliminating the need to maintain high speeds during low-pressure periods.
Data Source
Figure 1~2
Figure 3~4
AI summary
An electro-hydraulic control arrangement is equipped with an adjustable fluid pump and with a variable speed electric drive. A pressure detecting unit allows the detection of the fluid pressure. The main control circuit of said electro-hydraulic control arrangement comprises a rotational speed adjusting element of the electric drive as the adjusting element. The fluid pressure, and thus, for example, a force exerted by a cylinder, or a downstream adjusting variable, such as a position or a speed, can be controlled by means of the main control circuit. A displacement volume adjusting element of the fluid pump is actuated by means of a secondary adjusting chain as a function of the fluid pressure detected.