Elevator Brake Proximity Sensor Mounting for Thermal Drift Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Temperature changes affect the position of switching points in inductive proximity sensors used in elevator machinery brakes, leading to design tolerance issues and inaccuracies due to thermal expansion and resistance changes, especially in applications with small target movement and significant temperature fluctuations.
Innovation Solution
A temperature change compensation device is introduced between the inductive proximity sensor and its mounting parts, made of materials like polyphenylene sulfide doped with graphene, which expands oppositely to counteract switching point changes, maintaining sensor accuracy by adjusting the air gap between the sensor and target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an inductive proximity sensor is used in an elevator machinery brake, then the sensor can detect the presence or absence of the target (actuator), but temperature changes cause the switching point to move, leading to measurement inaccuracies
Solution Approach 1:
The patent applies thermal expansion by selecting mounting structure materials with specific thermal expansion coefficients that compensate for the sensor's temperature-induced switching point drift. The mounting structure expands or contracts with temperature changes in a way that counteracts the sensor's internal temperature effects, keeping the switching point stable relative to the target.
Solution Approach 2:
The patent changes physical parameters of the mounting structure, specifically the thermal expansion coefficient, to match or compensate for the sensor's temperature characteristics. By carefully selecting materials and designing the mounting structure's geometry, the system adjusts its thermal response to maintain measurement accuracy across temperature variations.
2Ease of manufacture
If the proximity sensor is mounted directly to the frame or armature part, then the mounting is simple, but thermal expansion of mounting parts causes additional switching point position changes
Solution Approach 1:
The patent introduces a temperature change compensation device as an intermediary element between the proximity sensor and the mounting structure. This compensation device acts as a mediator that absorbs or counteracts thermal expansion effects, isolating the sensor from temperature-induced position changes while maintaining a relatively simple mounting arrangement.
Solution Approach 2:
The compensation device utilizes controlled thermal expansion of its material to offset the thermal expansion effects on the sensor mounting. By selecting materials with appropriate thermal expansion coefficients and designing the compensation device's geometry, the system creates a balanced thermal response that maintains switching point stability.
3Length of moving object
If the target movement distance is small in the elevator brake application, then the brake response is precise, but the temperature-induced switching point movement becomes significant relative to the total movement range
Solution Approach 1:
The patent uses thermal expansion compensation to counteract the temperature-induced switching point movement that becomes significant when the target movement range is small. The compensation device's thermal expansion is designed to match and offset the sensor's temperature drift, ensuring that the switching point remains stable even when the actuator moves only small distances.
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the mounting structure and compensation device to counteract temperature effects before they affect the measurement. The compensation device is designed in advance with specific material properties and geometry that will automatically offset thermal drift during operation, maintaining accuracy without requiring active correction.
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 effectively mitigates temperature-induced switching point changes, ensuring precise monitoring and operation of elevator machinery brakes by compensating for thermal expansion and resistance drifts within the operating temperature range.
Implementation Method 1
the material of the temperature change compensation device is such that it expands to an opposite direction with respect to a change in a position of a switching point of the inductive proximity sensor in response to a temperature change
Implementation Method 2
An input current is provided to an oscillator that generates an alternating current to the coil, which, in turn, generates a magnetic field in front of the proximity sensor
Implementation Method 3
when a target made of conductive metal is brought in a zone defined by boundaries of the magnetic field, some of the energy is transferred into the target causing eddy currents flowing in the target surface
Data Source
AI summary
A machinery brake of an elevator includes a frame part including an electromagnet, an armature part, an inductive proximity sensor indirectly mounted to one of the following: the frame part, the armature part, and a target mounted to another of the following: the frame part, armature part. The machinery brake further includes, for establishing the indirect mounting: a temperature change compensation device mounted between the inductive proximity sensor and one of the following: the frame part, the armature part. Some aspects relate to a method for compensating a change in switching point of an inductive proximity sensor.