Hydraulic Accumulator Charging Control for Cyclic Molding Machines
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Solution Overview
Problem
Existing hydraulic systems for cyclically operating shaping machines, such as injection molding machines, face inefficiencies in energy use, reduced pump service life, and increased noise due to discontinuous pump operation at maximum delivery output, leading to energy loss and maintenance challenges.
Innovation Solution
Implementing a continuous operation of the pump with open-loop or closed-loop control to charge the hydraulic accumulator just before the start time of the hydraulic drive unit, reducing the need for maximum delivery output and minimizing leakage losses, thereby enhancing energy efficiency, pump longevity, and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the pump is operated discontinuously at maximum delivery output to charge the hydraulic accumulator quickly, then the charging time is reduced, but the pump service life is reduced and energy consumption increases
Solution Approach 1:
The pump is operated periodically rather than continuously, with multiple charging phases distributed throughout the cycle time. The control unit activates the pump at several intermediate times before the hydraulic drive unit starts, allowing the accumulator to be charged in stages rather than requiring a single continuous charging period at maximum pump output.
Solution Approach 2:
The hydraulic accumulator is charged in advance during intermediate phases before the actual need for hydraulic power. By distributing charging operations throughout the cycle time, the system prepares the accumulator progressively, eliminating the need for last-minute maximum-power charging that stresses the pump.
2Speed
If the pump is operated discontinuously at maximum delivery output, then the charging speed is increased, but the noise level increases due to constant acceleration and deceleration
Solution Approach 1:
The pump operates in periodic intervals rather than continuous maximum-power mode. By distributing charging operations throughout the cycle, the pump reaches steady-state operation more frequently, reducing the noise associated with repeated acceleration and deceleration from standstill.
3Power
If the hydraulic accumulator is charged to maximum pressure and maintained there, then the energy storage is maximized, but energy is lost through leaks reducing energy efficiency
Solution Approach 1:
Instead of maintaining static maximum pressure in the accumulator, the system dynamically adjusts the charging schedule based on when the hydraulic drive unit will operate. The accumulator is charged to the necessary level at appropriate times and then allowed to discharge, avoiding prolonged periods at maximum pressure where leakage losses would accumulate.
Solution Approach 2:
The accumulator is charged to the required level in advance of the hydraulic drive unit operation and then discharged when needed, rather than being maintained at maximum pressure continuously. This dynamic approach minimizes the time the accumulator spends at high pressure, reducing leakage losses while still ensuring adequate energy storage when required.
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 increases energy efficiency, extends pump service life, and decreases noise levels by optimizing pump operation and reducing energy consumption, while maintaining the hydraulic system's performance.
Implementation Method 1
at least one pump (4) and at least one hydraulic accumulator (5), wherein the at least one hydraulic accumulator (5) can be discharged for driving the at least one hydraulic drive unit (2) and can be charged up by operation of the at least one pump (4)
Data Source
AI summary
A hydraulic system for a cyclically operating shaping machine includes at least one hydraulic drive unit for cyclically driving a component of the shaping machine at a start time; at least one pump; and at least one hydraulic accumulator which can be discharged for driving the at least one hydraulic drive unit and which can be charged up by operation of the at least one pump. An open-loop or closed-loop control unit is also provided for control of the at least one pump. The open-loop or closed-loop control unit is adapted to operate the at least one pump continuously until the start time of the at least one hydraulic drive unit to charge up the at least one hydraulic accumulator until the start time of the hydraulic drive unit.