Electric Work Vehicle Motor Restraint for Low-Speed Shift Errors
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Solution Overview
Problem
Electric work vehicles face issues where sudden movement or inappropriate operation can occur when the motor is at a rotation speed of 0 rpm or rotates minutely, due to incorrect procedural operation of shift and accelerator tools.
Innovation Solution
The electric work vehicle is equipped with a motor controller that performs a motor restraining control, restricting the motor's output when the shift and accelerator tools are operated inappropriately, ensuring the vehicle starts traveling or working appropriately even at low motor speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor is operated at low rotation speed (0 rpm or minimal rotation), then the vehicle can be started or work devices can be operated, but sudden movement or inappropriate operation may occur due to incorrect procedural operation of shift and accelerator tools
Solution Approach 1:
The motor controller performs a motor restraining control as a preliminary action before normal operation. When the motor rotation speed is at or below a predetermined first rotation speed (0 rpm or minimal rotation), the controller restricts motor output even if the accelerator operation tool is operated, preventing sudden movement before the operator can properly engage the shift operation tool.
Solution Approach 2:
The motor controller continuously monitors the motor rotation speed and the operational states of both the shift operation tool and accelerator operation tool. Based on this feedback, the controller dynamically adjusts motor output restriction, releasing the restraint when appropriate conditions are met (shift tool engaged and motor speed exceeds first rotation speed) while maintaining safety during low-speed operations.
2Object-affected harmful factors
If the motor output is restricted during low rotation speed operation, then sudden movement is prevented, but the motor rotation speed increase may be limited
Solution Approach 1:
The motor restraining control is designed to be dynamic rather than static. The control state changes based on real-time conditions: when the motor rotation speed exceeds the first rotation speed and the shift operation tool is properly engaged, the restraining control is released or relaxed, allowing normal motor acceleration. This dynamic adjustment ensures speed restriction only when necessary for safety.
3Reliability
If the motor restraining control is applied when accelerator operation tool is operated after shift operation tool at low rotation speed, then inappropriate work device operation is prevented, but the operational responsiveness is reduced
Solution Approach 1:
The motor restraining control acts as a preliminary safety measure that is automatically released when proper operational conditions are established. Once the motor rotation speed exceeds the first rotation speed and the shift operation tool engagement is confirmed, the restraining control is lifted, allowing immediate responsive operation without prolonged delay.
Data Source
AI summary
An electric work vehicle includes a motor to drive at least either a travel device or a work device, a shift operation tool to shift a rotational power to drive the travel device or the work device, an accelerator operation tool to raise and lower a motor rotation speed of the motor, and a motor controller configured or programmed to control the motor rotation speed in response to an operation on the accelerator operation tool and to perform a motor restraining control to restrict an output from the motor in response to the shift operation tool and the accelerator operation tool being operated in an inappropriate procedure with the motor rotation speed being equal to or less than a predetermined first rotation speed.