Wheel Loader Steering Handle Prioritization Valve
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Solution Overview
Problem
The existing control device for wheel loaders with both handle and lever operations for steering has a complex configuration, leading to unstable prioritization of handle operations, resulting in potential unintentional steering due to shared fluid pressure and valve actuation issues.
Innovation Solution
A steering device with a handle prioritization valve that uses differential or absolute pressure to shut off pilot hydraulic pressure from the lever electromagnetic control valve, ensuring handle operations are prioritized by controlling fluid flow through a simplified mechanism, including throttles and check valves to stabilize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sequence valve and electromagnetic control valves are provided separately from the handle control valve and lever control valve to prioritize handle operations, then handle operation prioritization is achieved, but the configuration becomes complex
Solution Approach 1:
The patent combines the handle prioritization function with the existing handle control valve by providing a throttle member and prioritization valve body integrated into the handle control valve assembly. This merging eliminates the need for separate sequence valves and electromagnetic control valves, achieving handle operation prioritization while simplifying the overall valve configuration.
2Reliability
If the sequence valve and electromagnetic control valves are actuated by operating fluid flowing through the handle control valve, then handle operation prioritization is implemented, but the action becomes unstable due to shared fluid pressure
Solution Approach 1:
The patent segments the fluid pressure control by providing a dedicated throttle member that creates a separate pressure control path. The throttle member regulates the operating fluid flow to the prioritization valve body independently from the main handle control valve flow, ensuring stable sequence valve actuation without being affected by fluctuations in the main hydraulic circuit.
Solution Approach 2:
The throttle member acts as an intermediary element between the handle control valve and the prioritization valve body. It mediates the fluid pressure by providing a controlled, stable pressure source that ensures reliable sequence valve operation while isolating the prioritization mechanism from the variability of the main hydraulic system.
3Ease of operation
If the pressure at both ends of the lever control valve is the same, then the lever operation is simplified, but the supply of operating fluid from the lever control valve to the steering cylinder is blocked
Solution Approach 1:
The patent extracts the lever control valve's pressure control function by providing a separate throttle member that regulates fluid flow to the prioritization valve body. This extraction allows the lever control valve to operate with simplified pressure control while ensuring that operating fluid can still be supplied to the steering cylinder through the prioritization valve body when needed.
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 solution effectively prioritizes handle operations, preventing unintentional steering and stabilizing the control mechanism, even when the lever is mistakenly operated during handle use, with a simpler configuration that maintains operational reliability.
Implementation Method 1
a handle prioritization valve that uses differential or absolute pressure to shut off pilot hydraulic pressure from the lever electromagnetic control valve
Implementation Method 2
a pump, a handle control valve, a lever electromagnetic control valve, and a handle prioritization valve. The steering valve uses pilot hydraulic pressure to control the supply direction of operating fluid to the steering cylinder. The pump supplies operating fluid to the steering cylinder via the steering valve.
Implementation Method 3
a steering cylinder for pivoting a front frame in relation to a rear frame by expansion and contraction of the steering cylinder
Data Source
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AI summary
A mechanism for prioritizing a handle operation is achieved with a simple configuration and the mechanism is actuated in a stable manner in a wheel loader in which steering can be operated by a handle operation and a lever operation. The steering device includes a handle (21), a joystick (22), steering cylinders (23L, 23R), a steering valve (25), a pump (30), an orbit roll (26) for supplying pilot pressure to the steering valve (25) according to a handle operation, a lever electromagnetic control valve (27) for supplying pilot pressure to the steering valve (25) according to a joystick operation, and a handle prioritization valve (28). The handle prioritization valve (28) shuts off pilot hydraulic pressure supplied to the steering valve (25) from the lever electromagnetic control valve (27) due to a differential pressure in a hydraulic circuit that is produced by operating fluid flowing through the orbit roll (26) during a handle operation.