Hydraulic Selector Valve Control for Combined Travel and Work Operation
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Solution Overview
Problem
Conventional hydraulic control apparatuses experience a sudden drop in traveling speed when shifting from a single operation state to a combined operation state, and fail to secure necessary driving pressure for work actuators while preventing excessive increase in traveling speed.
Innovation Solution
A hydraulic control apparatus with a flow-path selector valve and a flow-path switching control unit that adjusts the communication flow path's opening area based on the detected driving state of the work actuator, ensuring necessary driving pressure and controlling traveling speed during combined operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the communication flow path is opened when working pressure is higher than traveling pressure, then traveling speed sudden decrease is prevented, but hydraulic fluid flows excessively into the traveling motor causing work actuator pressure insufficiency and excessive traveling speed increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the opening area of the communication flow path based on the detected driving state of the work actuator. Instead of simply opening or closing the communication flow path, the system varies the opening area to a predetermined value that maintains stable traveling speed while ensuring sufficient driving pressure for the work actuator. This resolves the contradiction by transforming a binary state (open/closed) into a continuous adjustable parameter (opening area), allowing optimization of both traveling speed stability and work actuator pressure.
2Stability of the object's composition
If the communication flow path is opened to prevent sudden deceleration, then traveling speed stability improves, but the flow rate to traveling motor increases excessively causing work pressure loss
Solution Approach 1:
The system changes the parameter of the communication flow path from a binary open/closed state to a continuously adjustable opening area. By setting the opening area to a predetermined value based on the work actuator's driving state, the system maintains stable traveling speed while preventing excessive flow rate to the traveling motor, thus preserving work actuator operating efficiency.
Solution Approach 2:
The patent implements feedback control by detecting the driving state of the work actuator and using this information to adjust the communication flow path opening area. The flow-path switching control unit continuously monitors the work actuator's state and adjusts the communication flow path accordingly, creating a closed-loop control system that maintains both traveling speed stability and work actuator productivity.
3Speed
If hydraulic fluid flows freely through the communication flow path, then traveling speed sudden drop is prevented, but work actuator pressure is not secured
Solution Approach 1:
The patent transforms the communication flow path from a fully open state to a controlled state with a predetermined opening area. This parameter change allows hydraulic fluid to flow smoothly enough to prevent sudden traveling speed drop, while the restricted opening area ensures sufficient pressure is maintained for the work actuator. The predetermined opening area is specifically designed to balance these two competing requirements.
Data Source
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AI summary
Provided is a hydraulic drive apparatus (20) for a work machine, capable of suitably shifting from a single operation state to a combined operation state while securing the driving pressure of a work actuator in the combined operation state and reducing an increase in the speed of a traveling motor. The hydraulic drive apparatus (20) includes a flow-path selector valve (70) and a flow-path switching control unit that operates the valve. The supply selector valve (70) has a first position (71) for the single operation state and a second position (73) for the combined operation state, being capable of, at the first position (71), forming a first flow path (73a) connected to a first pump (21), a second flow path (73b) connected to a second pump (22), and a connecting flow path (73c) providing communication between the first flow path (73a) and the second flow path (73b). When the driving state of a work actuator (45) is deviated from an allowable range in the combined operation state, the flow-path switching control unit reduces the opening area of the connecting flow path (73c) as compared with that when the driving state is within the allowable range.