Hydraulic Pump Motor Energy Regeneration Control
Solution Overview
Problem
In existing hydraulic excavator systems, the swing deceleration regenerative control is inefficient due to the hydraulic fluid being supplied only to one pump/motor, leading to limited regeneration of swing deceleration regenerative energy, and the displacement of the hydraulic pump/motor is controlled minimally, resulting in a poor regenerative ratio.
Innovation Solution
A system with two hydraulic circuits connected through a combining flow path, where a control device detects swing deceleration and adjusts the flow to allow both pumps/motors to operate as motors, increasing suction pressures to regenerate energy from the hydraulic fluid, utilizing both pumps/motors to enhance energy regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hydraulic fluid is supplied only to one pump/motor during swing deceleration, then the system structure remains simple, but the regenerative energy is insufficient
Solution Approach 1:
The patent combines two hydraulic circuits (first hydraulic circuit with swing hydraulic motor and second hydraulic circuit with second pump/motor) through a combining flow path. During swing deceleration, the hydraulic fluid from the swing hydraulic motor is supplied to both the first pump/motor and the second pump/motor simultaneously, merging the regenerative capacity of both pumps/motors to increase the total regenerative energy while maintaining a relatively simple hydraulic circuit structure through the use of a combining flow path and switching devices.
2Loss of energy
If the displacement of the hydraulic pump/motor is controlled minimally, then the control system remains simple, but the regenerative ratio is poor
Solution Approach 1:
The patent employs variable displacement pump/motors (first pump/motor and second pump/motor) that can dynamically adjust their displacement based on operating conditions. During swing deceleration, the control device increases the displacement of both pump/motors to maximize their capacity to regenerate energy from the hydraulic fluid, thereby improving the regenerative ratio. The displacement is controlled through regulators (12a-19a) that adjust the tilt angle of swash plates, enabling dynamic adaptation to different operational requirements while maintaining a manageable control system through centralized control by the control device (57).
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 efficiently regenerates energy from the hydraulic fluid during swing deceleration, reducing fuel consumption by utilizing both pumps/motors to supply energy back to the drive source, thereby lowering fuel costs.
Implementation Method 1
the hydraulic pressure force (brake force) resistant to inertia energy makes a hydraulic pump/motor that is connected to a hydraulic pump in a closed circuit style, operate as a hydraulic motor
Implementation Method 2
controls the displacement of the first pump/motor and the displacement of the second pump/motor to make respective suction pressures higher than respective discharge pressures so that the first pump/motor and the second pump/motor operate as motors
Data Source
AI summary
To provide a work machine capable of efficiently regenerating the energy owned by hydraulic fluid during a swing deceleration. In the present invention, when a swing deceleration detection section 57a detects the state of a revolving upperstructure 102 being decelerated, when an operation judgment section 57c judges the state that a double-tilting pump/motor 14 is not supplying hydraulic fluid to any of a boom cylinder 1 and an arm cylinder 3, and when the number of double-tilting pumps/motors 14, 18 having supplied hydraulic fluid to a swing hydraulic motor 7 in the state before the swing deceleration detection section 57a detects the state of the revolving upperstructure 102 being decelerated is equal to one or more, a pump valve control section 57d controls changeover valves 43a, 45b, 45d, 49d to open and increases the displacements of the double-tilting pumps/motors 14, 18 to the side to make suction pressures become higher than discharge pressures of the double-tilting pumps/motors 14, 18 so that the double-tilting pumps/motors 14, 18 operate as motors.