Elevator Shaft Door Guard with Force Sensor
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Solution Overview
Problem
Existing elevator door safety systems, particularly those using photoelectric sensors and light curtains, struggle to accurately detect small objects like pet leashes, leading to potential accidents when the elevator door closes.
Innovation Solution
A door guard arrangement featuring a force sensor with a contact element and a spring mechanism that activates a safety switch when an object is clamped by the door, allowing for detection of objects regardless of size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photoelectric sensors or light curtains are used to detect obstacles, then the door safety protection is provided, but small objects like pet leashes cannot be detected accurately
Solution Approach 1:
The patent replaces the optical detection system (light curtains and photodetectors) with a mechanical force sensor system. The force sensor detects obstacles through mechanical contact force when the door attempts to close, converting the optical detection approach into a mechanical one. This substitution enables detection of small objects like pet leashes that cannot be reliably detected by light-based systems, as the mechanical force sensor responds to any physical obstruction regardless of its size or optical properties.
2Area of stationary object
If the light curtain covers a large area to detect obstacles, then the detection coverage is improved, but the complexity and cost of the safety device increases
Solution Approach 1:
The patent extracts the detection function from the complex optical system and concentrates it into a single force sensor located at the door closing path. Instead of using multiple light transmitters and photodetectors distributed across a large area to create comprehensive coverage, the invention uses one force sensor that detects any obstacle in the door's closing path through mechanical contact. This extraction simplifies the system while maintaining effective detection coverage.
Solution Approach 2:
The force sensor serves multiple functions: it detects obstacles of any size, determines the presence of clamped objects, and triggers door reopening or car movement prevention. This single component replaces the need for multiple specialized sensors and control elements, reducing overall system complexity while providing comprehensive safety functionality across the entire door opening area.
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 system effectively prevents elevator door strikes by detecting objects of any size, enhancing safety for both passengers and pets without increasing complexity or cost.
Implementation Method 1
a force sensor with a contact element and a spring mechanism with a spring
Data Source
AI summary
A shaft door for an elevator has a door guard arrangement that includes a force sensor and a safety switch, wherein the force sensor comprises a contact unit and a spring mechanism with a spring. The force sensor senses a presence of an object clamped by the shaft door due to the shaft door closing wherein the contact element contacts the clamped object and transfers a force to the spring. The spring mechanism activates the safety switch to send a door-to-open command to a door operator of the elevator when the force transferred to the spring exceeds a stiffness of the spring.