Work Machine Forward Reverse Control System with Automatic Cancellation
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Solution Overview
Problem
Conventional forward/reverse control systems for work machines, such as wheeled excavators or wheel loaders, do not allow for automatic cancellation of the second control state without operating the first forward/reverse control means, leading to unintended travel if the second control state is left active.
Innovation Solution
A forward/reverse control system with a cancellation instructing means that allows the second control state to be cancelled and returned to the first control state through operation of the first forward/reverse control means, without requiring an operation of the first control means, using a switching instruction means and a use determination means, including a seat occupancy detection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a second forward/reverse control means is added to allow forward/reverse switching without letting go of the steering wheel, then ease of operation is improved, but device complexity increases and risk of unintended travel increases if the second control state is not properly cancelled
Solution Approach 1:
The control system is segmented into two distinct control states: a first control state where the F-N-R lever unit controls forward/reverse switching, and a second control state where a separate forward/reverse switch unit controls switching. This segmentation allows each control means to operate independently without interfering with the steering wheel operation, while the control means integrates and manages both states to prevent unintended travel
Solution Approach 2:
The control means monitors the operational state of both the F-N-R lever unit and the forward/reverse switch unit, and automatically manages transitions between control states. When the forward/reverse switch unit is operated, the control means detects this input and switches from the first control state to the second control state, ensuring that the operator's intent is recognized and the appropriate control mode is activated without requiring additional manual steps
2Reliability
If the second control state is maintained without automatic cancellation, then reliability is improved by allowing continuous use of the second control means, but harmful factors increase due to risk of unintended travel if the operator leaves the seat
Solution Approach 1:
The control means is configured to automatically cancel the second control state and return to the first control state when the operator's seat is detected to be unoccupied. This preliminary anti-action prevents unintended travel by proactively switching to the F-N-R lever unit control mode before any accidental operation can occur, counteracting the potential harmful effect of leaving the second control state active
Solution Approach 2:
The control system performs self-monitoring through the seat occupancy detection means and automatically manages the transition between control states without requiring manual intervention from the operator. When the seat becomes unoccupied, the system autonomously detects this condition and switches from the second control state back to the first control state, ensuring safety without adding operational burden to the operator
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
Enables automatic return to the first control state when the second control state is left active, preventing unintended travel and ensuring safe operation by allowing cancellation of the second control state without relying on the first control means operation.
Implementation Method 1
the second forward/reverse control means is determined to be not in use when no occupancy of an operator's seat is detected by a seat occupancy detection means
Data Source
AI summary
A forward/reverse control system for a work machine cancels a second control state, in which forward/reverse switching control is performed by a second forward/reverse control means, by an operation of a first forward/reverse control means to return to a first control state in which forward/reverse switching control is performed by the first forward/reverse control means. The system is provided with a F-N-R lever unit 30 (the first forward/reverse control means) and F-N-R switch unit 40 (the second forward/reverse control means) that instruct forward, reverse or neutral, a controller 42 which performs forward/reverse switching control by giving priority to an instruction from the F-N-R lever unit 30 over an instruction from the F-N-R switch unit 40, and a selector switch 41 which by an operation of a switching control member 41a, instructs the controller 42 to switch to the second control state or to cancel the second control state. As a consequence, the system has made it possible to return to the first control state without an operation of the first forward/reverse control means.