Travel Control Device for Working Vehicles
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Solution Overview
Problem
Conventional travel control devices for working vehicles, such as wheel loaders, require a new speed change lever when transitioning from a four-speed to a five-speed transmission, increasing component complexity and cost.
Innovation Solution
A travel control device with a switching device for manual or automatic speed change, a speed stage selecting device for selecting speed stages excluding the first speed, and a control device that sets the selected speed stage as an upper limit, allowing manual speed change to the first speed and assigning other speed stages to a common selecting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a new speed change lever is prepared for five-speed transmission, then the transmission can support additional speed stages, but the device complexity and component count increase
Solution Approach 1:
The speed change lever is designed to perform multiple functions: it can select speed stages 2-5 through the speed stage selecting device, and it can also select speed stage 1 through the first speed selecting device. This universal design allows the same lever to work with both four-speed and five-speed transmissions without requiring different hardware configurations.
Solution Approach 2:
The speed selection function is segmented into two independent devices: the speed stage selecting device for selecting speed stages 2-5, and the first speed selecting device for selecting speed stage 1. This segmentation allows each device to be optimized for its specific function while together they provide complete speed stage selection capability.
2Extent of automation
If automatic speed change range includes all speed stages, then complete automatic control is achieved, but manual control flexibility is reduced
Solution Approach 1:
The system dynamically adapts the automatic speed change range based on the selection of the first speed stage. When speed stage 1 is selected via the first speed selecting device, the automatic speed change range is set to exclude stage 1, ensuring that manual selection takes precedence and the system operates in a hybrid mode respecting both automatic control capabilities and manual operator intent.
Data Source
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AI summary
To provide a travel control device for a working vehicle, including a speed change lever that is applicable even when a transmission in which speed stages are set to be larger by one stage is applied, the travel control device comprises a switching device (41) that switches speed changed by a transmission (3) either manually or automatically, a speed stage selecting device (30b) that selects a speed stage out of a plurality of speed stages of the transmission (3), and a first speed selecting device (40) that changes the speed stage manually down to a first speed separately from the speed stage selecting device (30b), regardless of a switching state of the switching device (41), wherein the speed stage selecting device (30b) selects the speed stages including a second speed or more but excluding the first speed, and a control device (10) is further provided, which controls the transmission (3) based on instructions sent from the switching device (41), the speed stage selecting device (30b), and the first speed selecting device (40).