Articulated Wheel Loader Joystick Link Mechanism
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Solution Overview
Problem
Conventional articulated work vehicles face challenges in installing the pilot valve due to limited space under the driver's seat, restricting the flexibility in choosing the valve's location.
Innovation Solution
The work vehicle design includes a joystick lever in the cab with a link mechanism that transmits its operation to a control valve on the front frame or at the center of articulation, allowing the pilot valve to be positioned away from the driver's seat, including on the front frame, with an assisting force or counterforce mechanism to adjust the operation feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pilot valve is disposed directly under the driver's seat to transmit joystick operation with a simple configuration, then the ease of operation is improved, but the adaptability of valve placement is worsened due to limited space under the seat
Solution Approach 1:
A link mechanism is introduced as an intermediary component to transmit the operation of the joystick lever to the control valve. This mediator allows the control valve to be positioned at locations other than directly under the driver's seat, such as on the front frame or center of articulation, thereby resolving the spatial conflict while maintaining operational connectivity.
Solution Approach 2:
The link mechanism extends the transmission path from the joystick lever to the control valve in a spatial dimension that bypasses the constrained area under the driver's seat. By utilizing the available space in other regions of the vehicle (front frame, center of articulation), the system achieves flexible valve placement without compromising the directness of operation transmission.
2Adaptability or versatility
If the control valve is positioned away from the driver's seat to increase installation flexibility, then the adaptability is improved, but the ease of operation is worsened due to longer transmission distance
Solution Approach 1:
The link mechanism serves as an efficient intermediary that maintains direct and reliable transmission of operational forces over the extended distance between the joystick lever and the remotely positioned control valve. This mechanical intermediary ensures that operational responsiveness is preserved despite the increased spatial separation.
Solution Approach 2:
The transmission system is segmented into distinct components: the joystick lever, the link mechanism, and the control valve. This segmentation allows each component to be optimized independently, with the link mechanism specifically designed to bridge the gap between the operator interface and the valve actuation point, maintaining operational efficiency across the distributed architecture.
3Adaptability or versatility
If a link mechanism is added to transmit joystick operation to remotely positioned control valve, then the adaptability of valve placement is improved, but the device complexity is worsened
Solution Approach 1:
The link mechanism is designed as a straightforward mechanical intermediary consisting of basic linkages and connection points. By using simple, well-understood mechanical components rather than complex electronic or hydraulic transmission systems, the added complexity is minimized while achieving the goal of flexible valve placement.
Solution Approach 2:
The link mechanism utilizes the natural movement and forces already present in the steering system. The joystick lever's operation naturally generates the forces needed to actuate the control valve through the link mechanism, eliminating the need for additional power sources or complex control systems. The system essentially uses its own operational forces to drive the transmission mechanism.
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
This configuration provides greater flexibility in valve placement and improves operational feel by varying the force required to operate the joystick lever based on the vehicle's state, enhancing both installation options and operator experience.
Implementation Method 1
a hydraulic actuator which is driven by hydraulic pressure to change the steering angle of the front frame with respect to the rear frame
Implementation Method 2
a first link mechanism which is disposed on the lower side of the cab and transmits the operation of the joystick lever to the control valve
Data Source
Figure 1
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Figure 3
AI summary
A wheel loader (1) is an articulated type in which a front frame (11) and a rear frame (12) are linked. The wheel loader (1) comprises steering cylinders (21 and 22), a pilot valve (42), a joystick lever (24), and a link mechanism (90). The steering cylinders (21 and 22) are driven by hydraulic pressure to vary the steering angle (θs) of the front frame (11) with respect to the rear frame (12). The pilot valve (42) is configured to control the flow of fluid supplied to the steering cylinders (21 and 22). The joystick lever (24) is disposed in a cab (5) provided on the rear frame (12) and is operated by an operator. The link mechanism (90) is disposed on the lower side of the cab (5) and is configured to transmit the operation of the joystick lever (24) to the pilot valve (42).