There are many different kinds of displacement sensor and application field expands unceasingly in recent years, more and more innovative technology has been applied to the sensor, we through several typical applications in industrial production, to learn more about different kinds of displacement sensor.
1, The linear displacement sensor can be used to measure the displacement of the shield machines cylinder
In tunnel construction equipment, the structure characteristics and supporting facilities of shield machines are different. In some complex shield machine whose functions are systematic and diverse, including mechanical, hydraulic, measurement, control and so on. For example, some kinds of composite shield machines, there are many functions including excavation system, main drive system, propulsion system, grouting system and hydraulic system, etc.
As a kind of linear sensor, displacement sensor is mainly used to measure the mechanical displacement, every group of the propulsion system of shield machine oil cylinder, all are equipped with a displacement sensor, is used to measure the displacement of oil cylinder propelling.
In advance, propulsion oil cylinder sticking out, gripper would provide the anti-force of the shield machine on the pipe. The pressure of the cylinder can be independent adjustment, by looking at the each group of oil cylinder propulsion data detecting by displacement sensor, construction personnel in the control room can be real-time monitoring of each group of oil cylinder stroke and pressure. By adjusting the push pressure and speed of each cylinder, the correction and adjustment of the shield machine can be realized.
2. Application of static magnetic grating displacement sensor in elevator control system
Elevator in the modern building is related to people's life and property safety of important traffic tools, is a floor to improve complete sets of equipment, it composed by traction system, guidance system, safety device and electric control system. How to improve the efficiency of the elevator, reduce the energy consumption and the mechanical wear, prolong the service life, are very important research topics.
At present the elevator control widely adopted two ways, one is using microcomputer as signal control unit, achieve automatic scheduling and collect operation function of the lift, drag the control are done by frequency converter; The second control mode is to replace the microcomputer with programmable controller (PLC) to control the signal set.
Static magnetic grating displacement sensor in the elevator control system is the role of the leveling control adjustment, the elevator electric control system is "central nervous", in order to make the elevator has high efficiency, acceleration and deceleration should have a suitable speed limit, and changes should be smooth, that’s all need to have a reasonable design of electric control system.
Static magnetic grating sources installed in the elevator shaft and parallel to the outdoor layer, each layer has one, static magnetic grating scale installed on capsules, length of 1.2 meters, underground installed two static magnetic grating sources, used to test whether capsules is at the end place and movement direction. The static magnetic gate displacement sensor is used to control the elevator level, which can realize the intellectualization of elevator control, the elevator ride is comfortable, and the feeling of flat layer does not change as load variation when start or decelerate.
3. LVDT linear displacement sensor ensures efficient operation of gas turbineA gas turbine contains various control valves, such as regulating air flow or preventing air flow. The precise monitoring and control of the flow from the control valve allows the gas turbine to operate efficiently while minimizing energy waste. The brake will move the control valve, and the feedback device will send the valve position information back to the gas turbine control system, indicating the opening or closing status and degree of the valve.
Although other technologies are considered as feedback devices, the power generation industry has standardized LVDT linear displacement technology. The LVDT displacement sensor is a simple device consisting of only a few coils and a ferrous conductor, which can withstand high impact and vibration, which can meet specifications even in extremely dirty environment. The laser can't work with dirt and dust, and capacitors and eddy current sensors can't measure long strokes. The potentiometer, magnetic resistance displacement sensor and the rope displacement sensor cannot meet the temperature, vibration and intrinsic safety requirements well.
In the use of sensors to monitor gas turbine valves, the normal operation condition or the environment, can achieve + 250 ° C temperature. These sensors can separate the LVDT electronics from the LVDT coil in the gas turbine control system. The modern LVDT dimensions have been reduced by as much as 80%, which is applicable to any given stroke, and the LVDT displacement sensor can achieve high accuracy and durability.
An LVDT linear displacement sensor performance is reliable, reusable, high accuracy, and low cost, both in the gas turbine running and can play an important role in plant renovation project, the maximum advancing efficiency.
4. Precision control of displacement sensor in quantitative filling machine
Rotary automatic quantitative filling machine is advanced production equipment which is widely purchased by beverage and liquor manufacturers. Using quantitative filling form, is every electrical spreading filling valve is equipped with a measuring cylinder, controlled by the liquid level sensor (float type) its quantitative replenishment and filling, liquid is transferred from material cylinder to measuring cylinder, and then filling to packaging container.
This is a dynamic measurement quantitative form, how to realize the high speed operation of the equipment while accurate measurement and control is a big challenge. The key technical difficulties is the detection precision of the measuring cylinder level, magnetostrictive displacement sensor for its reliability, high resolution, small temperature drift value and rich interface signals perfectly fit the technical requirements for accurate quantitative filling, become the standard component of mainstream rotary automatic quantitative filling machine.
5. The application of displacement sensor in the entertainment kinetic instrument
The demand for displacement sensor is also very high on the entertainment dynamic stage of simulation. At present, large entertainment venues in many cities can be seen everywhere, from small motorized vehicles that can only accommodate two to three people, to large dynamic cinema with dozens or even hundreds of people. Especially in large theme parks such as the Disney World, large studios and other places. In order to achieve the safety and stability of mechanical devices, these systems are basically hydraulic driven. They are generally used some long-stroke hydraulic cylinder with displacement sensors, as scheduled program to make a variety of different types and the direction of movement, as the audience's body to move, let them feel the sense of reality as it were.
Displacement sensor is usually installed long stroke of the hydraulic cylinder, mainly in order to achieve the accurate displacement of the piston rod so as to ensure that on the basis of the measurement to the position of the piston, and to realize the remote control.
6. The application of linear displacement sensor on the injection molding machine
For precision injection molding machine, the displacement control is the most important part, which directly affects the quality of the plastic products, and the speed of its manifestation is the intrinsic relationship between the products quality and production efficiency.
The displacement of the injection screw is used to control the amount of the melt material, so as to ensure accurate injection molding. Accurate control of locking mould is also necessary condition for precision injection molding, otherwise, it can produce incomplete mold and cannot complete injection molding. Therefore, the effective control of injection position and the speed of its characterization are very important for precision injection molding.
In this cycle engineering, the locking mould, injection table movement, injection molding and ejection are required to be accurately controlled. Early applications, the potentiometer ruler is widely used in injection molding machine, but because of this products both in the accuracy, reliability, travel and life are far less magnetostrictive displacement sensor, because contact, carbon brush after repeated use for a long time cannot avoid wear and tear, eventually lead to failure. However, the accuracy of the magnetostrictive displacement sensor can meet the requirements, but the anti-vibration ability is poor, and the blind area at both ends of the installation is large and not suitable for use in the limited space.
Now, therefore, the position control system technically needs non-contact, no wear, and durable, easy installation, compact appearance, connected to fieldbus displacement sensor. Inductive linear displacement sensor is a new detection principle, not only inherited the many advantages of magnetostrictive linear displacement sensor and magnetic field interference resistance, vibration resistance, compact appearance has better performance. Due to the design of signal acquisition and processing in two circuit boards, the flexibility of the sensor output type is greatly increased; only need to change different signal processing circuit boards can change the sensor output type.
7. The application of displacement sensor in laser cutting
In the shape change and has surface uneven obstacle, displacement sensor can automatically detect the changes, and according to the change automatically adjust the laser cutting head height, make it always keep up with distance on the surface of the workpiece. This can increase the processing speed without constant supervision. The displacement sensor adopted at domestic and abroad market is basically capacitive, and its structure and shape are suitable for processing head, and equipped with detecting signal processing unit.The laser head is composed of displacement capacitance sensor and nozzle body. The sensor is composed of two different metal conical shells. The inner shell is ceramic insulated medium, the shell layer is chosen to be grounded and insulated with the inner layer, and the sensor will be shielded when working. The lower part of the inner shell of the conical tip is connected to a ring of metal that is insulated from the outer layer; this ring of metal is the two poles that make up a capacitive sensor. From the inner shell, there is a channel in the signal acquisition system connect the sensor to work through, in turn metal inner shell to launch pad (annular sheet metal) charged, the probe upper in laser processing machine, laser beam through the inner metal casing wear while working out.