Industrial Vehicle Hydraulic Interlock With Throttled Cargo Handling
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Solution Overview
Problem
Conventional hydraulic drive apparatuses for industrial vehicles lack an effective interlocking feature that restricts cargo handling operations when the switching member is turned to the interlock releasing side, leading to ineffective interlocking as drivers often keep the switch on to avoid frequent switching, thereby eliminating the interlocking functionality.
Innovation Solution
A hydraulic drive apparatus with a lock valve and logic valve system that controls the flow of hydraulic oil based on the switch's state, allowing cargo handling by one operation while restricting the other operation when the switch is on, ensuring the interlocking feature functions effectively by only releasing the interlock during the intended operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a switch is used to control interlocking for cargo handling operations, then cargo handling can be restricted when the switch is off, but the driver may keep the switch on all the time to avoid frequent switching, which eliminates the interlocking functionality
Solution Approach 1:
A logic valve is introduced as an intermediary between the switch and the lock valve. The logic valve receives pilot pressure from the switch and controls the lock valve's state based on this pilot pressure. When the switch is on, the logic valve applies pilot pressure to the lock valve, causing it to lock (restrict cargo handling). When the switch is off, the logic valve releases pilot pressure, allowing the lock valve to unlock (allow cargo handling). This intermediary mechanism ensures the interlocking function works as intended while maintaining ease of operation.
2Device complexity
If the lock valve is controlled directly by the switch, then the structure is simple, but the interlocking feature becomes ineffective when the driver keeps the switch on
Solution Approach 1:
The logic valve serves as a mediator that translates the switch's on/off state into the appropriate lock valve state. Instead of direct control, the logic valve uses hydraulic pilot pressure to control the lock valve. This adds one component but ensures reliable interlocking functionality while maintaining operational simplicity.
Solution Approach 2:
The system uses hydraulic pilot pressure control to manage the lock valve state. The logic valve controls the flow of pilot pressure to the lock valve based on the switch position, using hydraulic principles to achieve reliable control without complex mechanical or electrical systems.
3Reliability
If cargo handling is restricted by keeping the lock valve locked, then safety is improved, but the operational flexibility is reduced when the driver needs to perform cargo handling
Solution Approach 1:
The lock valve state is made dynamic and controllable through the logic valve and switch mechanism. The system can switch between locked (safe) and unlocked (operational) states based on the driver's needs. The logic valve dynamically adjusts the lock valve state using pilot pressure, allowing the system to adapt between safety and operational flexibility as required.
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
The apparatus ensures the interlocking feature is secured by only releasing the interlock during the specific operation, preventing unintended cargo handling and maintaining effective interlocking functionality by restricting the other operation when the switch is turned on.
Implementation Method 1
a logic valve (12) that controls a flow route of pilot pressure to the lock valve (13) according to a state of the switch (4)
Implementation Method 2
a lock valve (13) that is locked or unlocked according to a state of the switch (4)
Data Source
Figure 1
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Figure 3
AI summary
A hydraulic drive apparatus (100, 200) for an industrial vehicle includes a cargo-handling device (2), a hydraulic control device (1, 201, 203), a cargo-handling-device operating member (3), and a switching member (4). When a first operation of the cargo-handling-device operating member (3) is performed, an open-close valve (20) is opened to hydraulic oil flowing in a first direction to cause the hydraulic oil to bypass a throttle (23). When a second operation of the cargo-handling-device operating member (3) is performed while the switching member (4) is in a first state, the open-close valve (20) is closed against hydraulic oil flowing in a second direction to cause the hydraulic oil to flow through the throttle (23). The throttle (23) provided in a flow route of the hydraulic oil between a main control valve (11) and the cargo-handling device (2) reduces a flow rate of the hydraulic oil to restrict cargo handling.