阅读说明：本技术 一种基于飞秒光纤光栅的加速度传感器 (Acceleration sensor based on femtosecond fiber bragg grating ) 是由 赵德春 于 2021-08-18 设计创作，主要内容包括：本发明提供了一种基于飞秒光纤光栅的加速度传感器,其包括：悬浮系统、质量块、传输支撑臂、柔性铰链、杠杆支撑臂、光纤光栅和框架。本发明实现了光纤光栅加速度传感器的工业化生产,将工作频率提高到2000Hz以上,灵敏度提高到80pm/g。本发明采用一种U型结构的悬浮系统,让质量块悬浮在中央。U型结构的悬浮系统可确保其运动方向与测试方向相同,杜绝其他方向的振动对测试方向的影响。本发明采用杠杆原理,将质量块的移动通过杠杆来放大,提高了加速度传感器的灵敏度。本发明采用可调整质量的杠杆支撑臂来提高加速度传感器的本征频率,提高了传感器的工作频率。(The invention provides an acceleration sensor based on a femtosecond fiber grating, which comprises: the device comprises a suspension system, a mass block, a transmission supporting arm, a flexible hinge, a lever supporting arm, a fiber grating and a frame. The invention realizes the industrial production of the fiber grating acceleration sensor, improves the working frequency to more than 2000Hz and improves the sensitivity to 80 pm/g. The invention adopts a suspension system with a U-shaped structure, so that the mass block is suspended in the center. The suspension system with the U-shaped structure can ensure that the motion direction of the suspension system is the same as the test direction, and the influence of vibration in other directions on the test direction is avoided. The invention adopts the lever principle, amplifies the movement of the mass block through the lever, and improves the sensitivity of the acceleration sensor. The invention adopts the lever supporting arm with adjustable mass to improve the eigenfrequency of the acceleration sensor and improve the working frequency of the sensor.)

1. The utility model provides an acceleration sensor based on femto second fiber grating which characterized in that:

it includes: the device comprises a suspension system (1), a mass block (2), a transmission supporting arm (3), a flexible hinge (4), a lever supporting arm (5), a fiber grating (8) and a frame (9);

the suspension system (1) comprises two pairs of U-shaped leaf springs and a horizontal leaf spring (101), the two pairs of U-shaped leaf springs are respectively a first pair of U-shaped leaf springs (102) and a second pair of U-shaped leaf springs (103), the mass block (2) is connected to two pins of the central U-shaped leaf spring, and the central U-shaped leaf spring is the first pair of U-shaped leaf springs (102); the central U-shaped leaf spring is connected with the outer U-shaped leaf springs through the horizontal leaf springs, and the outer U-shaped leaf springs are the second pair of U-shaped leaf springs (103); two feet of an external U-shaped leaf spring are connected to the frame (9); all the leaf springs are designed to have the same elastic coefficient;

the mass block (2) is positioned in the center of the suspension system (1), and two pairs of U-shaped leaf springs and one pair of horizontal leaf springs in the suspension system (1) ensure that the mass block (2) only moves along the measuring direction;

the transmission supporting arm (3) connects the suspension system (1) with the lever supporting arm (5), one end of the fiber grating (8) is fixed on the frame (9), the other end of the fiber grating (8) is fixed on the lever supporting arm (5), and pretension force of not less than 2nm is applied to the fiber grating (8); when the mass block (2) moves in the measuring direction under the action of inertia force, the flexible hinge (4) is used as a lever supporting point, and the movement of the mass block (2) is transmitted to the lever supporting arm (5).

2. The femtosecond fiber grating-based acceleration sensor according to claim 1, wherein: the fiber grating (8) is a II-type fiber grating engraved by femtosecond laser.

3. The femtosecond fiber grating-based acceleration sensor according to claim 1, wherein: further comprising a first fibre attachment point (6) and a second fibre attachment point (7); one end of the fiber grating (8) is fixed on the frame (9) through a second fiber connection point (7), and the other end of the fiber grating (8) is fixed on the lever support arm (5) through a first fiber connection point (6).

4. The femtosecond fiber grating-based acceleration sensor according to claim 1, wherein: a plurality of inner holes are formed in the lever supporting arm (5), the mass of the lever supporting arm (5) is adjusted, and the eigenfrequency of the acceleration sensor is freely controlled.

5. The femtosecond fiber grating-based acceleration sensor according to claim 4, wherein: three inner holes are arranged in the lever supporting arm (5).

Technical Field

The invention relates to a sensor, in particular to an acceleration sensor.

Background

Conventional electronic accelerometers are susceptible to electromagnetic interference, generate noise, and inherently cause measurement inaccuracies. The fiber bragg grating acceleration transducer based on femtosecond laser writing is essentially explosion-proof and electromagnetic interference resistant, and is very suitable for being applied to vibration monitoring.

The acceleration sensor can be applied to various occasions, such as: vibration measurement, amplitude measurement, transportation monitoring, vibration compensation of load cells, preventive maintenance on wind turbines, and maximum vibration monitoring.

All current acceleration sensors based on fiber bragg gratings use type I gratings.

The mechanisms of the current acceleration sensor based on the fiber bragg grating are divided into two major categories:

2.1 the first type consists of cantilever beam and mass block. The fiber grating is attached to the surface of the cantilever beam. When the sensor vibrates, the mass block can cause the cantilever beam to deform under the action of the inertia force, so that the central wavelength of the fiber bragg grating is changed.

2.2 the second category is based on flexible hinge technology. The mass block is fixed on the flexible hinge and generates micro-amplitude vibration along with the flexible hinge, so that the change of the central wavelength of the fiber grating is caused.

The prior art has the following problems:

the reliability is poor. The I-type fiber grating needs to peel off a coating layer of the optical fiber at first and then write the grating through ultraviolet light, so that the tensile resistance of the optical fiber is damaged. This I-grating is inherently not suitable for high intensity, high frequency vibrations.

The acceleration sensor based on the cantilever beam and the mass block structure has low response frequency, low sensitivity and unevenness.

The acceleration sensor based on the flexible hinge technology cannot obtain frequency response of kilohertz level and large sensitivity because the mass blocks directly act on the hinge structure.

The acceleration sensors with the above two structures can generate reverse crosstalk due to the structural defects. When measuring vibrations in one direction, vibrations in other directions may cause inaccuracies in the measurement.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an acceleration sensor based on a femtosecond fiber grating, which comprises: the device comprises a suspension system, a mass block, a transmission supporting arm, a flexible hinge, a lever supporting arm, a fiber grating and a frame;

the suspension system comprises two pairs of U-shaped leaf springs and a horizontal leaf spring, the two pairs of U-shaped leaf springs are respectively a first pair of U-shaped leaf springs and a second pair of U-shaped leaf springs, the mass block is connected to two pins of the central U-shaped leaf spring, and the central U-shaped leaf spring is the first pair of U-shaped leaf springs; the central U-shaped leaf spring is connected with the outer U-shaped leaf springs through the horizontal leaf springs, and the outer U-shaped leaf springs are the second pair of U-shaped leaf springs; two feet of an external U-shaped leaf spring are connected to the frame; all the leaf springs are designed to have the same elastic coefficient;

the mass block is positioned in the center of the suspension system, and two pairs of U-shaped leaf springs and one pair of horizontal leaf springs in the suspension system ensure that the mass block only moves along the measuring direction;

the transmission supporting arm connects the suspension system with the lever supporting arm, one end of the fiber grating is fixed on the frame, the other end of the fiber grating is fixed on the lever supporting arm, and pretension of which the length is not less than 2nm is applied to the fiber grating; when the mass block moves in the measuring direction under the action of inertia force, the flexible hinge is used as a lever supporting point to transmit the movement of the mass block to the lever supporting arm.

As a further improvement of the invention, the fiber grating is a II-type fiber grating inscribed by femtosecond laser.

As a further improvement of the present invention, the optical fiber connector further comprises a first optical fiber connection point and a second optical fiber connection point; one end of the fiber grating is fixed on the frame through the second fiber connection point, and the other end of the fiber grating is fixed on the lever support arm through the first fiber connection point.

As a further improvement of the invention, a plurality of inner holes are arranged in the lever supporting arm, the mass of the lever supporting arm is adjusted, and the eigenfrequency of the acceleration sensor is freely controlled.

As a further improvement of the invention, three inner holes are arranged in the lever supporting arm.

The invention has the beneficial effects that:

the invention realizes the industrial production of the fiber grating acceleration sensor, improves the working frequency to more than 2000Hz and improves the sensitivity to 80 pm/g.

The invention adopts a suspension system with a U-shaped structure, so that a mass block is suspended in the center. The suspension system with the U-shaped structure can ensure that the motion direction of the suspension system is the same as the test direction, and the influence of vibration in other directions on the test direction is avoided.

2, the invention adopts the lever principle, amplifies the movement of the mass block through the lever, and improves the sensitivity of the acceleration sensor.

3, the invention adopts the lever supporting arm with adjustable mass to improve the eigenfrequency of the acceleration sensor and improve the working frequency of the sensor.

4, the invention adopts the fiber grating which is inscribed by the femtosecond laser as the sensing element, has extremely high strength and extremely high fatigue resistance, and is very suitable for industrialized use.

Drawings

Fig. 1 to 6 are schematic perspective views of different angles of an acceleration sensor based on a femtosecond fiber grating according to the present invention;

FIG. 7 is a front view of an acceleration sensor based on femtosecond fiber gratings according to the present invention;

FIG. 8 is a side view of an acceleration sensor based on femtosecond fiber gratings according to the invention;

fig. 9 is a view of the B-B interface of fig. 8.

The names of the components in the figure are as follows:

the device comprises a suspension system 1, a mass block 2, a transmission supporting arm 3, a flexible hinge 4, a lever supporting arm 5, a first optical fiber connecting point 6, a second optical fiber connecting point 7, an optical fiber grating 8 and a frame 9;

a horizontal flat spring 101, a first pair of U-shaped flat springs 102, and a second pair of U-shaped flat springs 103.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

An acceleration sensor based on femtosecond fiber gratings, comprising: the device comprises a suspension system 1, a mass block 2, a transmission supporting arm 3, a flexible hinge 4, a lever supporting arm 5, a first optical fiber connecting point 6, a second optical fiber connecting point 7, an optical fiber grating 8 and a frame 9; the fiber grating 8 is a type II fiber grating engraved by femtosecond laser.

The suspension system 1 is composed of two pairs of U-shaped leaf springs 102 and a horizontal leaf spring 101, and the two pairs of U-shaped leaf springs are a first pair of U-shaped leaf springs 102 and a second pair of U-shaped leaf springs 103. The mass 2 is connected to the two legs of the central U-shaped leaf spring (first pair of U-shaped leaf springs 102). The central U-shaped leaf spring is connected to the outer U-shaped leaf springs by means of horizontal leaf springs (second pair of U-shaped leaf springs 103). Two legs of the outer U-shaped leaf spring are connected to the outer frame. All leaf springs are designed to have the same spring constant.

The mass 2 is located in the center of the suspension system 1. Two pairs of U-shaped leaf springs and a pair of horizontal leaf springs in the suspension system 1 ensure that the mass block 2 only moves along the measuring direction, thereby fundamentally avoiding the occurrence of crosstalk.

The transport support arm 3 connects the suspension system 1 with the lever support arm 5. One end of the fiber grating 8 with the II type femtosecond grating is fixed on the frame 9 through the second fiber connection point 7, and the other end of the fiber grating 8 is fixed on the lever supporting arm 5 through the first fiber connection point 6 and applies pretension force of not less than 2nm to the fiber grating 8. When the mass 2 moves in the measuring direction under the action of inertia force, the flexible hinge 4 is used as a lever supporting point to transmit the movement of the mass 2 to the lever supporting arm 5. The mass block 2 slightly moves, and the lever support arm can be greatly moved under the amplification effect of the lever, so that the end of the optical fiber 8 connected with the lever support arm 5 is greatly moved, the central wavelength of the optical fiber grating 8 is greatly changed, and the sensitivity of the acceleration sensor is improved.

Three or more inner holes are arranged in the lever supporting arm 5, so that the mass of the lever supporting arm 5 can be adjusted, the eigenfrequency of the acceleration sensor can be freely controlled, and the working frequency and the resonant frequency of the acceleration sensor can be infinitely improved.

The invention adopts a suspension system with a U-shaped structure, so that the mass block is suspended in the center. The suspension system with the U-shaped structure can ensure that the motion direction of the suspension system is the same as the test direction, and the influence of vibration in other directions on the test direction is avoided.

The invention adopts the lever principle, amplifies the movement of the mass block through the lever, and improves the sensitivity of the acceleration sensor.

The invention adopts the lever supporting arm with adjustable mass to improve the eigenfrequency of the acceleration sensor and improve the working frequency of the sensor.

The invention adopts the fiber grating engraved by the femtosecond laser as the sensing element, has extremely high strength and extremely high fatigue resistance, and is very suitable for industrial use.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.