Excavator Hydraulic Flow Sharing for Boom Raise and Swing
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Solution Overview
Problem
Existing hydraulic drive systems for working machines, such as hydraulic excavators, experience energy wastage when both boom raising and swing operations are performed simultaneously due to independent supply lines for the swing motor and boom cylinder, leading to unnecessary activation of the swing relief valve and hydraulic oil discard.
Innovation Solution
A hydraulic drive system with a controller that manages the flow of hydraulic oil between the first and second pumps, using a third control valve to divert oil from the swing motor to the boom cylinder when the swing motor reaches a steady state, and shutting off this diversion when the swing motor is in a high-load state, thereby optimizing energy usage by connecting and disconnecting the supply lines based on load pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If independent supply lines are used for swing motor and boom cylinder, then energy loss from throttling is reduced, but swing relief valve activates unnecessarily causing hydraulic oil discard
Solution Approach 1:
A third control valve is introduced as an intermediary component between the second hydraulic pump and both the swing motor and boom cylinder. This valve acts as a mediator that dynamically directs hydraulic oil flow based on operational conditions, preventing unnecessary activation of the swing relief valve while maintaining independent control capabilities. The third control valve receives control signals from the controller and adjusts its opening degree to optimize flow distribution, thereby eliminating the technical contradiction between reducing throttling loss and preventing hydraulic oil discard.
2Loss of energy
If third control valve is opened to supply hydraulic oil to boom cylinder from second pump, then energy efficiency improves, but swing motor may not reach steady state
Solution Approach 1:
The controller implements feedback control by monitoring the operational state of the swing motor and dynamically adjusting the opening degree of the third control valve accordingly. When the swing motor reaches a steady state, the controller increases the third control valve's opening to improve energy efficiency by supplying hydraulic oil from the second pump to the boom cylinder. Conversely, when the swing motor is accelerating or under high load, the controller reduces the opening to ensure the swing motor receives sufficient hydraulic oil. This feedback mechanism resolves the contradiction between energy efficiency and swing motor steady state reliability.
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 efficiently uses energy by minimizing wasteful consumption during simultaneous boom raising and swing operations, reducing unnecessary hydraulic oil discard and optimizing hydraulic oil distribution based on load pressures, thus enhancing energy efficiency without requiring new configurations.
Implementation Method 1
an on-off solenoid valve which is disposed between the boom operating device and the third control valve and opens and closes based on a command current from the controller
Implementation Method 2
a first hydraulic pump that supplies the hydraulic oil to the boom cylinder; a second hydraulic pump that supplies the hydraulic oil to the swing motor
Implementation Method 3
a relief valve that is provided between the second hydraulic pump and the swing motor
Data Source
AI summary
In a specific state where the raising operation of a boom 25 and the swing operation of an upperstructure 21 are performed at the same time to supply a hydraulic oil from a first pump 2 to a cylinder 7a through a first valve 6a, and to supply the same from a second pump 3 to a motor 7b through a second valve 6b, a controller 10 outputs the command current for opening a valve 13, and supplies a part of the hydraulic oil supplied to the motor 7b from the second pump 3 to the cylinder 7a through the third valve 6c when the motor 7b does not reach a steady swing state, and outputs a command current for closing the valve 13 when the motor 7b is in the steady swing state.