In an era of deep integration of industrial automation and intelligent operation and maintenance, real-time and accurate monitoring of equipment operating status is a core requirement for improving production efficiency and ensuring system safety. Vibration, as the most direct and sensitive signal reflecting the health of machinery, has become a key indicator in industrial monitoring systems. Vibration sensors are the core devices for capturing this crucial signal. With its high precision and high reliability, it has been widely used in various industrial scenarios, providing solid data support for predictive maintenance of equipment and powerfully promoting the improvement of industrial intelligence.
What is a vibration sensor?
A vibration sensor is a precision sensing device that can detect the vibration state of an object and convert mechanical vibration signals into electrical signals. Its core function is to capture the subtle vibration characteristics generated during equipment operation and transmit these characteristic signals to the data acquisition and analysis system, thereby revealing the equipment's operating status, potential faults or performance changes, and providing key evidence for equipment condition monitoring, fault diagnosis and health management.
Based on the different physical quantities measured, vibration sensors can generally be divided into the following three categories:
1. Displacement vibration sensor
Its core function is to measure the displacement of an object's vibration. It is suitable for low-frequency, high-amplitude vibration scenarios and can accurately capture the displacement changes of an object's vibration. It is widely used in the foundation vibration monitoring of large mechanical equipment and the low-frequency vibration detection of building structures.
2. Velocity vibration sensor
With the measurement of object vibration velocity as its core, the output signal is proportional to the vibration velocity, focusing on the overall vibration evaluation of the equipment. It can quickly determine the overall stability of equipment operation and is commonly used for routine vibration monitoring of general mechanical equipment such as motors and fans.
3. Accelerometer vibration sensor
It focuses on measuring the acceleration of object vibration, and features high sensitivity and fast response speed. It is suitable for high-frequency vibration and fault diagnosis analysis, and can capture subtle vibration anomalies in equipment operation. It is a core sensor type for fault diagnosis of industrial equipment.
How do vibration sensors work?
The core principle of vibration sensors is to convert mechanical signals into electrical signals based on specific physical effects or structural changes. Their operation mainly depends on the coordinated operation of the mechanical receiving unit and the electromechanical conversion unit.
Specifically, the sensor does not directly convert the original mechanical quantities of the object being measured (such as vibration velocity, frequency, acceleration, etc.) into detectable and processable electrical signals. Instead, it first senses and receives the vibration of the object being measured through a mechanical receiving unit, converts the original vibration signal into a measurable intermediate mechanical quantity, and then the electromechanical conversion unit converts the mechanical quantity into a corresponding electrical signal, thereby realizing the effective monitoring and measurement of the vibration state and ensuring the efficient and accurate transmission of vibration information.
1. Mechanical receiving principle
The function of the mechanical receiving unit is to capture the vibration signal of the object being measured. Depending on the measurement method, it can be divided into the following two types：
a. Relative type
The sensor is fixed on a stationary reference support and makes contact with the object being measured via a contact rod. When the object vibrates, the contact rod moves synchronously with the object and drives the recording device, thereby acquiring the relative vibration of the object relative to the reference body. The measured value can only be equivalent to absolute vibration when the reference body is absolutely stationary. This method is suitable for scenarios with stable reference points, such as fixedly installed equipment or structural testing platforms.
b. Inertial type
The sensor is directly fixed to the vibrating object being measured. Internally, it typically consists of an inertial mass block, an elastic support system, and a housing. When the housing vibrates with the object being measured, the mass undergoes relative motion due to inertia. By recording the relative displacement, velocity, or acceleration between the mass block and the shell, and combining this with a dynamic model, the absolute vibration of the measured object can be calculated. This method does not require a fixed reference point and is suitable for scenarios where it is difficult to establish an absolute reference, such as driving vehicles, ships, and earthquake monitoring.
2. Electromechanical conversion principle
After acquiring the vibration signal, the mechanical receiving unit needs to convert it into an electrical signal through an electromechanical conversion unit for subsequent processing. Commonly used electromechanical conversion principles include:
a. Piezoelectric type
Based on the piezoelectric effect, when a crystal (such as quartz or ceramic) is subjected to mechanical stress or vibration, the material deforms, causing the internal charge centers to shift. This generates a charge on the crystal surface that is proportional to the intensity of the vibration; the stronger the vibration, the greater the charge generated. This voltage signal, after amplification and filtering, can be used to measure the vibration amplitude and frequency. These sensors are characterized by fast response, wide frequency range, and high temperature resistance, and are commonly used for fault diagnosis and structural health monitoring of mechanical equipment.
b. Capacitive type
Vibration is sensed by detecting changes in capacitance. The sensor consists of fixed electrodes and movable electrodes. When vibration causes the movable electrodes to shift, the distance or relative area between the two electrodes changes, resulting in a change in capacitance. The circuit converts changes in capacitance into voltage signals, thereby reflecting vibration intensity or displacement characteristics. These sensors are highly sensitive and suitable for measuring low-frequency, minute vibrations. They can be used for vibration monitoring in precision instruments and electronic equipment.
c. Magnetoelectric type
Based on Faraday's principle of electromagnetic induction, vibration causes relative motion between the coil and the permanent magnet, resulting in a change in the magnetic flux passing through the coil, which in turn generates an induced electromotive force. The output electrical signal is proportional to the vibration velocity. These sensors are characterized by simple structure and strong anti-interference capabilities, and are suitable for velocity-type vibration monitoring of large rotating machinery, such as motors, fans and turbines.
d. Resistance strain type
This method utilizes the property that the resistance of a metal or semiconductor strain gauge changes with mechanical deformation. Vibration or strain is reflected by measuring the change in the strain gauge's resistance. This type of sensor has a simple structure, low cost, and is suitable for detecting static or low-frequency vibrations.
e. Eddy current type
Based on the electromagnetic eddy current effect, the sensor probe generates a high-frequency alternating magnetic field. When a conductive object being measured approaches, eddy currents are generated. These eddy currents react with the magnetic field, changing the impedance or inductance of the probe coil. By detecting changes in the distance between the probe and the object being measured, non-contact measurement of vibration displacement can be achieved, which is particularly suitable for monitoring the radial vibration and axis trajectory of rotating shafts.
Why monitor vibration?
During the operation of mechanical equipment, most early failures (such as component wear, loosening, imbalance, and misalignment) usually manifest in advance through abnormal changes in vibration characteristics. Therefore, vibration monitoring is widely recognized as one of the core technologies for predictive maintenance.
The specific value of vibration monitoring is reflected in the following four aspects：
1. Early warning of faults
Predictive maintenance is an advanced maintenance strategy based on the actual operating status of equipment and data analysis.Effective predictive maintenance relies on the quality of raw data. While industry giants like SKF and Fluke offer comprehensive ecosystem solutions, manufacturers like Renkeer are specialized in high-durability sensing for extreme environments like mining and metallurgy.By continuously monitoring the vibration characteristics of equipment, early warnings of potential faults can be achieved, guiding maintenance personnel to intervene at the optimal time.
Renkeer’s vibration and temperature sensors stand out by addressing the common issue of signal noise. By utilizing high-performance MEMS chips and chip-level digital filtering, these sensors effectively eliminate electromagnetic interference. This ensures that even the slightest mechanical shifts are captured accurately, preventing the false alarms that often lead to unplanned downtime.In the long run, it can significantly reduce maintenance costs.
2. Extending equipment lifespan
Developing a scientific and reasonable maintenance plan based on vibration data analysis can reduce unnecessary over-maintenance and avoid equipment damage caused by untimely fault handling, thereby significantly extending the mean time between failures and service life of the equipment.
3. Safety and management optimization
Vibration monitoring can promptly detect potential safety hazards, ensuring the safety and stability of the production process. Simultaneously, data-driven management decisions optimize management decisions, promoting the transformation of equipment management towards refinement and intelligence.
4. Optimizing design and process
During the product design phase, vibration testing can identify structural weaknesses and optimize the design to reduce vibration risks. In the manufacturing process, vibration monitoring can monitor the stability of the processing in real time, guide the adjustment of process parameters, and improve product quality and consistency.
From sensing equipment operating status to predictive maintenance decisions, vibration sensors are present throughout the entire process of industrial equipment health management. It is not only a tool for collecting vibration signals, but also an important data entry point connecting equipment operation and intelligent operation and maintenance systems.
With the deep integration of the Internet of Things, edge computing, artificial intelligence and wireless transmission technologies, vibration sensors are rapidly developing towards miniaturization, wireless connectivity, intelligence and multi-sensor fusion.
In the future, vibration sensors will play an even more critical and fundamental role in intelligent manufacturing systems, injecting stronger momentum into the digital transformation of the industrial sector.
