A cantilever beam type optical MEMS pressure sensor

Abstract

The present invention discloses a cantilever beam type optical MEMS pressure sensor, which includes a cantilever beam structure and a sensor protective housing. Above the cantilever beam structure, there is a U-shaped bracket composed of two pantograph carbon slide brackets. There is a certain gap between the beam arm and the base of the cantilever beam structure. The gap is 1 mm from the position near the root of the cantilever beam structure until before the U-shaped bracket, and the gap remains 1.5 mm from the U-shaped bracket to the position far from the root of the cantilever beam structure. An MEMS optical pressure sensitive chip is also installed on the cantilever beam structure. The sensor protective housing is fixed on the cantilever beam structure by screws. The sensor device of the present invention is installed on the basis of not changing the mechanical structure of the pantograph itself, and is conducive to assembly and disassembly. Therefore, it can be mass-installed on the pantographs of operating trains to monitor the working state between the pantograph and the catenary in real time and ensure safe operation.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, in particular to a cantilever beam optical MEMS pressure sensor. Background Art

[0002] Optical MEMS sensing technology is a technology that gradually emerged, developed and matured in the first decade of the 21st century. It integrates optical technology and MEMS (micro-electromechanical) technology, upgrading traditional optical sensing to "dynamic low-light sensing" technology with adjustable parameters. Sensors with this technology have the advantages of small size, light weight, easy installation, high sensitivity, dynamic response, passive measurement, and anti-electromagnetic interference.

[0003] Rail transit, such as high-speed rail and urban subway, has become the main means of transportation for people. Crowded travel has brought serious challenges to the operational safety of the rail transit industry. Among them, a good current collection relationship between the contact network and the pantograph is of utmost importance. If the pressure between the contact network and the pantograph is too high, the bow will break the network or the network will hit the bow. If the pressure is too low, the pantograph will have poor current collection and arcing between the pantograph and the network. Therefore, during the movement of the train, there must be a reasonable contact force between the pantograph and the contact network, so that the pantograph can safely introduce the current from the contact network into the traction converter system in the car body, thereby providing continuous and effective power for the train.

[0004] However, the high-voltage current collection technology in the rail transit industry has resulted in traditional electronic and electrical sensors being unable to measure the dynamic bow-catcher pressure during train operation due to limitations in electromagnetic interference. Therefore, only contact optical waveguide sensing technology can be used to measure the bow-catcher pressure value in real time online.

[0005] Currently, there is a technology that uses FBG (Fiber Bragg Grating) sensors to measure the pressure between the bow and the catenary during driving. However, since the carbon slide is a wearing part, it is necessary to remove the carbon slide from its bracket and pre-embed the sensor each time the slide is installed or replaced. This process takes a long time, is costly, and cannot be mass-produced.

[0006] In addition, since the heat energy generated by the friction between the contact network and the pantograph is simultaneously transferred to the FBG sensor, the irregular temperature signal of the return light is superimposed on the pressure signal, resulting in inaccurate and imprecise measured pressure. Therefore, this measurement technology is not suitable for online measurement of the pressure value between the pantograph and the catenary of operating vehicles.

[0007] In addition, different pantograph manufacturers produce different types of pantographs, such as spring box pantographs, leaf spring pantographs, shrapnel pantographs and tension spring pantographs. Given that each type of pantograph has a different force transmission mechanism, the mode of measuring the pressure between the contact network and the pantograph is different.

[0008] Therefore, a contact optical waveguide sensor technology based on pre-embedded non-wear parts is needed as a replacement, and optical MEMS sensing technology has well solved the above objective problems. Summary of the invention

[0009] The object of the present invention is to provide a cantilever beam optical MEMS pressure sensor to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A cantilever beam optical MEMS pressure sensor comprises a cantilever beam structure and a sensor protective shell, wherein a U-shaped bracket composed of two pantograph carbon skateboard brackets is arranged above the cantilever beam structure, a certain gap is provided between the beam arm of the cantilever beam structure and the base, the gap is 1 mm from the position close to the root of the cantilever beam structure to before the U-shaped bracket, and the gap from the U-shaped bracket to the position away from the root of the cantilever beam structure is maintained at 1.5 mm, a MEMS optical pressure sensitive chip is also installed on the cantilever beam structure, the sensor protective shell is fixed to the cantilever beam structure by screws, and its position is above the MEMS optical pressure sensitive chip, a waveguide fiber is connected to the MEMS optical pressure sensitive chip, there are two MEMS optical pressure sensitive chips, and the two MEMS pressure sensitive chips are arranged by orthogonal bonding.

[0012] As a further technical solution of the present invention: a leaf spring fixing hole is also provided on the cantilever beam structure.

[0013] As a further technical solution of the present invention: the cantilever beam structure is further provided with four limiting holes for fixing screws.

[0014] As a further technical solution of the present invention: a cantilever beam structure fixing hole is provided on the sensor protective shell.

[0015] As a further technical solution of the present invention: the gap between the cantilever beam structure and the sensor protective shell is sealed with foam.

[0016] As a further technical solution of the present invention: the pantograph carbon slide bracket is provided with carbon slide fixing holes.

[0017] As a further technical solution of the present invention: the cantilever beam structure is provided with a sensor protection shell fixing hole, and the sensor protection shell fixing hole corresponds to the position of the cantilever beam structure fixing hole.

[0018] As a further technical solution of the present invention: the pressure sensitive chip at the root of the cantilever beam structure is replaced by a temperature sensing chip.

[0019] As a further technical solution of the present invention: the MEMS pressure sensitive chip and the temperature sensing chip for temperature compensation are replaced by a fiber Bragg grating, a fiber F-P cavity or a sensitive element for electronic strain measurement.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This sensor is a passive device and is completely immune to the relatively high current receiving voltage on rail transit, such as 35 kV AC for high-speed railways and 1.5 kV DC for subways, and is not affected by electromagnetic interference; 2. This sensor can be directly installed on the leaf spring of the pantograph, and the carbon sliding plate is placed in its U-shaped bracket. Due to the good design structure and mechanical transmission effect, it can withstand a force of 300 N, and its designed measurement range is much larger than the pressure of 70 - 120 N between the pantograph and the catenary during normal train operation, effectively monitoring the dynamic pressure value between the pantograph and the catenary; 3. This sensor uses optical MEMS technology and is very sensitive to the transformation of deformation caused by force. Therefore, the accuracy of the pressure value can reach three thousandths, and the resolution can reach 0.1 N / pm; 4. This sensor device is installed on the basis of not changing the mechanical structure of the pantograph itself, and is conducive to assembly and disassembly. Therefore, it can be mass-installed on the pantographs of operating trains to monitor the working state between the pantograph and the catenary in real time and ensure safe operation. Description of the Drawings

[0021] Figure 1 It is the internal structure diagram of the cantilever beam type optical MEMS pressure sensor.

[0022] Figure 2 It is the external view of the cantilever beam type optical MEMS pressure sensor.

[0023] Figure 3 It is the side view of the cantilever beam type optical MEMS pressure sensor.

[0024] Figure 4 It is the combined side view of the cantilever beam structure and the protective shell of the sensor.

[0025] In the figure: 1. Cantilever beam structure; 2. Sensor protective shell; 3. MEMS optical pressure sensitive chip; 4. Limit hole; 5. Leaf spring fixing hole position; 6. Pantograph carbon sliding plate bracket; 7. Carbon sliding plate fixing hole position; 8. Sensor protective shell fixing hole position; 9. Cantilever beam structure fixing hole position; 10. Optical waveguide fiber. Detailed Embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Please refer to Figure 1-2 Example 1: A cantilever beam type optical MEMS pressure sensor, comprising a cantilever beam structure 1 and a sensor protective housing 2. Above the cantilever beam structure 1, there is a U-shaped bracket composed of two pantograph carbon slide bracket 6. There is a certain gap between the beam arm and the base of the cantilever beam structure 1. The gap is 1 mm from the position near the root of the cantilever beam structure 1 until before the U-shaped bracket, and the gap remains 1.5 mm from the U-shaped bracket to the position far from the root of the cantilever beam structure 1. An MEMS optical pressure sensitive chip 3 is also installed on the cantilever beam structure 1. The sensor protective housing 2 is fixed to the cantilever beam structure 1 by screws, and its position is above the MEMS optical pressure sensitive chip 3. A waveguide optical fiber 10 is connected to the MEMS optical pressure sensitive chip 3.

[0028] There are also leaf spring fixing holes 5 on the cantilever beam structure 1. There are also limit holes 4 for fixing screws on the cantilever beam structure 1. There are cantilever beam structure fixing holes 9 on the sensor protective housing 2. There are multiple MEMS optical pressure sensitive chips 3. There are carbon slide fixing holes 7 on the pantograph carbon slide bracket. There are sensor protective housing fixing holes 8 on the cantilever beam structure 1, and the sensor protective housing fixing holes 8 correspond to the cantilever beam structure fixing holes 9 in position.

[0029] After the U-shaped bracket transmits the dynamic pressure between the catenary and the pantograph through the carbon slide, the U-shaped bracket generates a displacement in the vertical direction, causing the bending of the beam arm of the cantilever beam structure 1. The MEMS optical pressure sensitive chip 3 pasted on the beam arm generates a corresponding deformation, resulting in the offset of the modulated resonant wavelength to measure the deformation value, and the corresponding pressure value can be calculated from the deformation value. The purpose of using two optical MEMS fiber F-P pressure sensitive chips with an orthogonal structure is to make the pressure value demodulated by the modulation and demodulation instrument more accurate through the mutual compensation of strains.

[0030] The specific structures and functions of each component are as follows:

[0031] Cantilever beam structure 1: There is a certain gap between the beam arm and the base of this cantilever beam structure. The gap is 1 mm from the position near the root of the cantilever beam structure until before the U-shaped bracket. This is the stress concentration area of the cantilever beam structure and can bear the deformation of the beam arm caused by a force of 300 N. The gap remains 1.5 mm from the U-shaped bracket to the position far from the root of the cantilever beam structure. This is used to generate a certain displacement for the U-shaped bracket after bearing the self-weight of the carbon slide and the pressure between the pantograph and the catenary, causing the beam arm to generate a bending deformation;

[0032] Sensor protective housing 2: This protective housing protects the MEMS optical pressure sensitive chip adhered to the cantilever beam structure. After fixing the sensor protective housing and the cantilever beam structure with screws, the gap is sealed with foam, which can prevent the MEMS optical pressure sensitive chip from being contaminated by carbon powder and copper shavings generated by the movement friction between the carbon slide plate and the catenary.

[0033] MEMS optical pressure sensitive chip 3: A pressure sensitive chip manufactured by optical microelectromechanical technology, which belongs to a passive device and is not immune to electromagnetic interference, and can measure the real-time pressure when the pantograph conducts current through the carbon slide plate.

[0034] Limit holes 4: Screws of a certain length are fixed in the 4 limit holes of the sensor. There is a certain gap between the screw cap and the upper surface of the beam arm of the cantilever beam structure. This limit can not only allow the beam arm to displace only in the vertical direction, but also keep the stroke from shortening.

[0035] Leaf spring fixing hole positions 5: The cantilever beam sensor and the leaf spring of the pantograph are fixedly connected with bolts;

[0036] Pantograph carbon slide plate bracket 6: The carbon slide plate is placed on this U-shaped bracket;

[0037] Carbon slide plate fixing hole positions 7: The carbon slide plate and this U-shaped bracket are fixedly connected with bolts;

[0038] Sensor protective housing fixing hole positions 8: Used for fixed connection with the cantilever beam structure;

[0039] Cantilever beam structure fixing hole positions 9:; Used for fixed connection with the sensor protective housing;

[0040] Waveguide optical fiber 10: The pigtail of the MEMS optical pressure sensitive chip, used to connect the fiber optic sensing modulation and demodulation instrument.

[0041] Example 2, on the basis of Example 1, the waveguide optical fiber 10 is connected to the fiber optic sensing modulation and demodulation instrument, and the results can be viewed intuitively.

[0042] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0043] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A cantilever beam type optical MEMS pressure sensor, comprising a cantilever beam structure (1) and a sensor protective housing (2), characterized in that, The cantilever beam structure (1) consists of a beam arm and a base. The beam arm and the base are integrally structured at the root position of the cantilever beam. There is a certain gap between the beam arm and the base at a position far from the root. At one end of the beam arm far from the root position, there is a U-shaped bracket composed of two pantograph carbon slide brackets. The pantograph carbon slide brackets are provided with carbon slide fixing holes. At one end of the base far from the root position, there is a leaf spring fixing hole. The gap is 1 mm from the position close to the root of the cantilever beam structure (1) until before the U-shaped bracket, and the gap remains 1.5 mm from the U-shaped bracket to the position far from the root of the cantilever beam structure (1). An MEMS optical pressure sensitive chip (3) is also installed on the cantilever beam structure (1). The sensor protective shell (2) is fixed to the cantilever beam structure (1) by screws, and its position is above the MEMS optical pressure sensitive chip (3). A waveguide optical fiber (10) is connected to the MEMS optical pressure sensitive chip (3). There are two MEMS optical pressure sensitive chips (3), and the two MEMS optical pressure sensitive chips (3) are arranged in an orthogonal bonding manner.

2. The cantilever optical MEMS pressure sensor according to claim 1, wherein Four limit holes (4) for fixing screws are also provided on the cantilever beam structure (1).

3. The cantilever optical MEMS pressure sensor according to claim 1, wherein The sensor protective shell (2) is provided with a cantilever beam structure fixing hole position (9).

4. A cantilever beam type optical MEMS pressure sensor according to claim 1, characterized in that, The gap between the cantilever beam structure (1) and the sensor protective shell (2) is sealed with foam.

5. The cantilever beam type optical MEMS pressure sensor according to claim 3, wherein, The cantilever beam structure (1) is provided with a sensor protective shell fixing hole position (8), and the sensor protective shell fixing hole position (8) corresponds to the cantilever beam structure fixing hole position (9).

6. An optical MEMS pressure sensor of a cantilever beam type according to claim 1, characterized in that, One of the MEMS optical pressure sensitive chips (3) at the root position of the cantilever beam structure (1) is replaced with a temperature sensing chip.

7. An optical MEMS pressure sensor of a cantilever beam type according to claim 6, characterized in that, The MEMS optical pressure sensitive chip (3) and the temperature sensing chip for temperature compensation are replaced with a fiber grating, a fiber F-P cavity or a sensitive element for electronic strain measurement.

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