Travel Straight Spool Control for Smooth Hydraulic Mode Switching
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Solution Overview
Problem
Construction machinery experiences travel shock when transitioning from travel-only operation to combined travel-work operation due to sudden changes in hydraulic fluid supply during the switching process.
Innovation Solution
A hydraulic system with a travel straight spool valve and control unit that gradually adjusts the flow rates of hydraulic pumps to minimize shock during transitions, using a switching flow rate calculation unit and limiting maximum supply flow rates to match combined travel-work operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hydraulic system switches from travel-only operation to combined travel-work operation, then the machine can perform both traveling and working functions, but travel shock occurs due to sudden changes in hydraulic fluid supply
Solution Approach 1:
The control unit calculates the target flow rate in advance before switching operation modes and gradually adjusts the actual flow rate to match the target flow rate over time. This preliminary calculation and gradual adjustment approach prevents sudden changes in hydraulic fluid supply that would otherwise cause travel shock when transitioning from travel-only to combined travel-work operation.
Solution Approach 2:
The system dynamically adjusts the flow rate of hydraulic pumps based on the current operation mode and transition state. During mode switching, the control unit continuously modifies the flow rate from the initial state to the target state, enabling smooth transition without abrupt changes. This dynamic adjustment mechanism eliminates travel shock while maintaining adaptability between different operation modes.
2Speed
If the flow rate of hydraulic pumps is suddenly changed during mode switching, then the response time is reduced, but travel shock increases
Solution Approach 1:
The control unit calculates the target flow rate in advance before switching operation modes and gradually adjusts the actual flow rate to match the target flow rate over time. This preliminary calculation and gradual adjustment approach prevents sudden changes in hydraulic fluid supply that would otherwise cause travel shock when transitioning from travel-only to combined travel-work operation.
Solution Approach 2:
The system implements periodic adjustment of the flow rate during mode transition, continuously updating the actual flow rate toward the target flow rate in controlled intervals. This periodic adjustment mechanism ensures that the flow rate changes smoothly over time rather than abruptly, reducing travel shock while maintaining adequate response speed for operation mode changes.
Data Source
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AI summary
One aspect of the present disclosure provides a hydraulic system for a construction machine, comprising: a traveling straight spool, comprising: first and second hydraulic pumps; first and second traveling motors operable by hydraulic fluid discharged from the first and second hydraulic pumps; a front work device operable by hydraulic fluid discharged from the first and second hydraulic pumps; a first section wherein, during traveling single operation, hydraulic fluid discharged from the first hydraulic pump is supplied to the first traveling motor, and hydraulic fluid discharged from the second hydraulic pump is supplied to the second traveling motor; and a second section wherein, during traveling combined operation, hydraulic fluid discharged from the first hydraulic pump is supplied to the first and second traveling motors, and hydraulic fluid discharged from the second hydraulic pump is supplied to the front work device; and a control unit which controls the supply flow rate of the first and second hydraulic pumps to change gradually in accordance with a section change rate during section change of the traveling straight spool.