Hydraulic Flow Combiner Control for Shock-Free Work Machines
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Solution Overview
Problem
Existing hydraulic systems in work machines like excavators experience operational shocks and inefficiencies due to frequent switching between flow-combining and non-flow-combining states of pressure oil from multiple pumps, leading to discomfort and unstable control, especially during operations requiring combined actuator movements.
Innovation Solution
A hydraulic drive system with a controller that manages the flow combiner valves to smoothly transition between single-pump and dual-pump operation based on the operator's lever position, maintaining a stable flow state by adjusting the suppliable flow rates of the primary and secondary pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the controller controls the flow combiner valve to combine pressure oil from both hydraulic pumps when drive pressure is equal to or less than a specified value, then operational shock is suppressed, but throttling losses increase and fuel efficiency deteriorates
Solution Approach 1:
The patent changes the control parameter from drive pressure to operation amount (lever displacement). By detecting the operation amount of the operation lever and comparing it with threshold values, the system determines when to switch between flow-combining and non-flow-combining states, eliminating the repeated switching caused by pressure fluctuations around a fixed pressure threshold.
2Object-affected harmful factors
If the controller switches between flow-combining and non-flow-combining states based on drive pressure threshold, then operational shock is reduced, but repeated switching occurs causing discomfort and unstable control
Solution Approach 1:
The control parameter is changed from drive pressure to operation amount. The controller compares the operation amount with predetermined threshold values to determine switching points between flow-combining and non-flow-combining states. This eliminates the repeated switching phenomenon that occurs when pressure fluctuates around a fixed threshold, providing stable and comfortable control.
3Loss of energy
If the primary pump supplies pressure oil alone when target flow rate is within primary pump capacity, then throttling losses are reduced, but flow rate insufficiency occurs when target flow rate exceeds primary pump capacity
Solution Approach 1:
The system dynamically switches between single-pump operation and dual-pump operation based on the operation amount. When the operation amount is small (within threshold), only the primary pump operates to reduce throttling losses. When the operation amount exceeds the threshold, both pumps operate in parallel to provide sufficient flow rate, ensuring the system can meet varying flow rate demands efficiently.
Data Source
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AI summary
To suppress shock caused by frequent switching of pressure oil, in a work machine comprising: a hydraulic drive device; an operation member; and a controller, the controller is configured to: until the operation member reaches a first position from an initial position, control a flow combiner valve so as to supply the pressure oil from a first hydraulic pump to a first hydraulic actuator; in a case where the operation member is operated in a direction of increasing the operation amount beyond the first position, control the flow combiner valve so as to supply the combined pressure oil to the first hydraulic actuator; and in a case where the operation member reaches a second position closer to the initial position than the first position from any position beyond the first position, control the flow combiner valve so as to supply the pressure oil from the first hydraulic pump to the first hydraulic actuator.