Power Regeneration Device for Work Machine
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Solution Overview
Problem
The existing power regeneration devices for working machines with hydraulic actuators suffer from poor responsiveness and inefficient energy recovery due to the large moment of inertia of hydraulic and electric motors, and excessive flow rate distribution to the control valve side, leading to suboptimal performance.
Innovation Solution
The power regeneration device controls the target flow rate and rotation speed of the electric motor based on the operator's control lever input, using a proportional solenoid valve to adjust the control valve opening area and minimize unnecessary hydraulic fluid flow, ensuring smooth actuator movement and high energy recovery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If return oil is branched to the control valve side in fixed proportions, then operability of hydraulic actuators is improved, but energy recovery efficiency deteriorates due to excessive flow to control valve
Solution Approach 1:
The patent applies dynamics by making the flow rate distribution to the control valve side dynamically adjustable rather than fixed. The control valve opening area is varied in real-time based on the deviation between target and actual rotation speeds of the electric motor, allowing the system to optimize the balance between actuator operability and energy recovery efficiency under different operating conditions.
Solution Approach 2:
The patent changes the parameter of control valve opening area to resolve the contradiction. By adjusting the opening area based on rotation speed deviation, the system dynamically modifies the flow rate distribution ratio, enabling it to minimize unnecessary flow to the control valve side while maintaining sufficient operability of hydraulic actuators.
2Device complexity
If fixed displacement hydraulic motor is used for power regeneration, then structure is simplified, but responsiveness deteriorates due to large moment of inertia
Solution Approach 1:
The patent applies feedback control by continuously detecting the actual rotation speed of the electric motor and comparing it with the target rotation speed. The control device uses this feedback to adjust the control valve opening area, which in turn regulates the flow rate to the hydraulic motor, enabling the system to achieve responsive actuator movement despite using a fixed displacement motor with large moment of inertia.
3Ease of operation
If more return oil flows to control valve side, then actuator operability is improved, but energy recovery amount decreases
Solution Approach 1:
The patent changes the parameter of control valve opening area to dynamically regulate the flow rate distribution. By adjusting this parameter based on rotation speed deviation, the system minimizes the flow rate to the control valve side to only what is necessary for maintaining actuator operability, thereby maximizing the amount of return oil available for energy recovery.
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 enhances the responsiveness of hydraulic actuators and maximizes energy recovery by optimizing the flow rate and rotation speed, maintaining high efficiency and responsiveness during operator operations.
Implementation Method 1
a hydraulic motor driven by return oil from the hydraulic actuator
Implementation Method 2
an electric motor connected mechanically to the hydraulic motor and driven thereby to generate electric power
Implementation Method 3
a proportional solenoid valve which adjusts the opening area of the control valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a lowering operation of a boom 111, the amount of operation of a control lever 4a is detected by a pressure sensor 16 and input to a controller 9. Based on the input operation amount, the controller 9 obtains a target flow rate Q0 of return oil discharged from a boom cylinder 3, calculates a deviation ΔQ between the target flow rate Q0 and an actual flow rate Q obtained from an actual rotation speed N of an electric motor 12 acquired by a rotation speed sensor 17, calculates a signal Sm for controlling the opening area of a proportional solenoid valve 7 in a manner allowing hydraulic fluid to flow to a control valve 2 in just as much as ΔQ, and controls an operation pilot pressure of the control valve 2 supplied from a sub-pump 8 in accordance with the signal Sm so that the hydraulic fluid will flow to the control valve 2 exactly in the amount of ΔQ. This ensures responsiveness of a hydraulic actuator when it starts to move and permits more energy to be recovered by the power regeneration device and a working machine furnished with the power regeneration device.