Joystick Steering Linkage Layout Without Pilot Valve Constraints
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Solution Overview
Problem
The existing steering systems for articulated work vehicles, such as those described in Japanese Patent Laid-open No. H11-321664, face limitations in layout flexibility due to the presence of a pilot valve in the link mechanism, which restricts the installation space and requires a sturdy link mechanism to handle the counterforces applied by biasing members and stroke end stops.
Innovation Solution
A steering device comprising a support part, a base member, a lever, a biasing member, and a transmission mechanism connecting part, where the base member is rotatably supported, the lever is rotatably supported by the support or base member, and the biasing member biases the lever to a predetermined position. This configuration allows for improved layout flexibility by eliminating the need for a mechanical transmission mechanism between the joystick lever and the electromagnetic pilot valve, thereby reducing the structural constraints on the link mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pilot valve is interposed in the link mechanism between the joystick lever and the front frame, then the steering control function is achieved, but the layout flexibility is restricted and the link mechanism requires increased structural strength
Solution Approach 1:
The patent extracts the pilot valve from the mechanical link mechanism between the joystick lever and front frame. The pilot valve is repositioned to be driven directly by the joystick lever without being part of the load-bearing link mechanism, thereby removing the conflicting requirement for both steering control and layout flexibility
Solution Approach 2:
The patent segments the steering control system into two independent parts: the mechanical link mechanism for position feedback and the pilot valve system for hydraulic control. This allows the link mechanism to be optimized for layout flexibility while the pilot valve is positioned separately to avoid structural constraints
2Ease of operation
If a pilot valve with biasing member and stroke end stop part is used to apply counterforce to the joystick lever, then the steering feedback is achieved, but the link mechanism layout is restricted
Solution Approach 1:
The patent extracts the counterforce generation function from the link mechanism by positioning the pilot valve separately. The biasing member and stroke end stop part are configured to act on the pilot valve body directly, allowing the joystick lever to receive feedback without requiring the link mechanism to accommodate these components
Solution Approach 2:
The patent introduces the pilot valve body as an intermediary element that receives mechanical input from the joystick lever and converts it to hydraulic control signals. This intermediary allows the decoupling of the feedback mechanism from the link mechanism layout constraints
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 enhances the flexibility of the steering system layout, reduces the structural requirements of the link mechanism, and allows for more efficient operation by applying counterforces based on the rotation state of the coupling shaft, improving the overall operational flexibility and reducing the need for a sturdy mechanical connection between the joystick lever and the pilot valve.
Implementation Method 1
The biasing member is interposed between the lever and the base member and biases the lever to a predetermined position with respect to the base member
Data Source
AI summary
A steering device for operating a work vehicle includes a support part, a base member rotatably supported by the support part, a lever rotatably supported by the support part or the base member, a biasing member and a transmission mechanism connecting part. The biasing member is interposed between the lever and the base member to bias the lever to a predetermined position with respect to the base member. The transmission mechanism connecting part configured to be connected to a transmission mechanism configured to transmit rotation based on a rotation angle of a steering shaft of the work vehicle to the base member. A restriction part may restrict rotation of the lever when an angle of the lever with respect to the base member reaches a predetermined angle.