Electric working machine
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Solution Overview
Problem
Manufacturing variations in electric working machines cause inconsistencies in the timing of signal transmission by switches, leading to performance variations across different units.
Innovation Solution
The use of two distinct switches that transmit signals based on predefined positions, rather than the operation member's position, to stabilize signal transmission timing and reduce performance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single switch changes signal type based on operation member position, then the structure is simple, but manufacturing variations cause timing variations in signal transmission
Solution Approach 1:
The single switch that changes signal type is divided into two separate switches: a first switch that always outputs a first signal and a second switch that always outputs a second signal. This segmentation eliminates the need for the switch to change signal types based on position, thereby reducing timing variations caused by manufacturing tolerances while maintaining structural simplicity through the use of standard switch components.
2Device complexity
If a single switch changes signal type based on operation member position, then the component count is low, but performance variations occur across different machines
Solution Approach 1:
By dividing the single position-dependent switch into two position-independent switches, each switch maintains consistent signal output characteristics across all machines. The first switch consistently outputs the first signal and the second switch consistently outputs the second signal, eliminating performance variations caused by manufacturing tolerances in position-dependent switches.
Solution Approach 2:
The control unit acts as an intermediary that receives signals from both switches and determines the operation member position based on the combination of first and second signals. This mediator approach allows the use of reliable, position-independent switches while still achieving position-based control functionality.
3Ease of operation
If position-dependent switches are used, then the control logic is simple, but the switching position varies due to manufacturing tolerances
Solution Approach 1:
The position-dependent switching mechanism is segmented into two position-independent switches. The first switch and second switch each have fixed, stable switching positions that do not vary with manufacturing tolerances. The control logic remains simple as it only needs to interpret the combination of signals from these two stable switches to determine position.
Data Source
AI summary
An electric working machine may include a control device configured to control an electric unit, an operation member, a first switch configured to be operated by the operation member, and a second switch configured to be operated by the operation member. The operation member may pass a second position and a third position while the operation member moves to the first position. The first switch may be configured to transmit a first signal which changes as the operation member moves from the second position to the first position to the control device when the operation member moves between the second position and the first position. The second switch may be configured to transmit a second signal to the control device when the operation member passes the third position. The control device may be configured to control the electric unit based on the first signal and the second signal.