Footboard Detection via Mechanical Tilt and Elastic Restoring Force
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Solution Overview
Problem
Existing solutions for detecting the presence of operators on waste collection vehicles are either overly complex, inconvenient, prone to mechanical failure, or suffer from sensor adjustment and interference issues, leading to unreliable safety stoppages.
Innovation Solution
A step device with a mobile support mechanism that connects the step to a fixed support via a substantially horizontal and vertical section, using a spring-loaded hinge and elastic forces to detect occupation by operators, allowing for stable and reversible positioning of the step, and integrating a detector to ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photoelectric cells or ultrasonic sensors are used to detect operator presence, then detection capability is provided, but the sensors are quickly out of service due to shocks and deformations from repeated exposure at the rear of vehicles
Solution Approach 1:
The patent replaces fragile optical and ultrasonic sensors with a mechanical detection system using a mobile support that tilts in response to operator weight. This mechanical approach eliminates the reliability issues of electronic sensors exposed to shocks and deformations at the rear of vehicles, while maintaining detection capability through the tilt mechanism's response to load.
2Ease of operation
If the step is made retractable by means of a parallelogram linkage provided with a hydraulic jack, then the step can be positioned, but the solution is disproportionately complex in relation to the functionality sought
Solution Approach 1:
The patent extracts the essential function of step positioning from the complex parallelogram linkage and hydraulic jack system. It retains only the mobile support that tilts to indicate occupation, eliminating the unnecessary complexity of retractable mechanisms while maintaining the ability to position and detect step occupation.
Solution Approach 2:
The mobile support automatically tilts to the appropriate position based on the operator's weight, eliminating the need for complex hydraulic control systems. The system self-adjusts through the mechanical tilt mechanism, providing simple and reliable step positioning without disproportionate complexity.
3Device complexity
If the inactive position of the step is used as an indication of the absence of an operator, then the solution is quite simple, but the step must be raised and lowered at each collection point which is inconvenient for operators
Solution Approach 1:
The patent introduces a mobile support as an intermediary element between the step and the detection system. This mobile support tilts to indicate occupation, providing a simple detection mechanism that does not require raising and lowering the step at each collection point, thereby maintaining operator convenience while achieving reliable detection.
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 provides reliable and convenient detection of operator presence, ensuring safety compliance by preventing vehicle movement above 30 km/h in reverse, while minimizing mechanical stress and operator inconvenience.
Implementation Method 1
an antagonistic elastic force tending to raise the distal end of the movable support and sized to be both non-zero and overcome by a load of minimum value
Data Source
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AI summary
The device has a movable support (4) supporting a stair (2) and mounted tilting, with a mechanically controlled amplitude displacement, on a fixed support (1) around an axis (Y), under the effect of weight of an occupant (P) of the stair and an elastic antagonistic force developed by a Belleville type elastic washer stack (6). A detector is placed in a mutual support zone (Z2) to detect the rotation of the support (4) between two limited angular displacement positions. The stair is rotatably mounted on the support (4) between an inactive dressed position and a horizontal operational position.