Desensitization type load grating sensor

Abstract

The utility model provides a desensitization type load grating sensor, which comprises a protective shell consisting of a sensor bottom plate and a sensor cover plate, an elastic body and a grating protective cover are arranged in the protective shell, the elastic body is connected with an optical fiber leading to the outside of the protective shell, and a grating area of the optical fiber is fixed on the elastic body. The elastomer is fixed on the sensor base plate, and the deformation direction of the elastomer is opposite to the grating deformation direction. The optical grating is simple in structure, has the function of protecting the optical grating when the load is stretched, and can be compatible with desensitization and temperature compensation at the same time.

Description

Technical Field

[0001] The utility model relates to the field of wind power, in particular to a desensitization type load grating sensor. Background Art

[0002] With the rapid development of wind power, the power generation capacity of wind turbines is getting larger and larger, which causes the blades of wind turbines to become longer and heavier. As an important component of the operation status of wind turbines, load sensors need to have more stable detection capabilities.

[0003] A common grating load sensor consists of a base plate, an elastomer, a grating and a protective shell. The elastomer has many structural types and is also the most important structural component of the sensor. It can serve as a fixing part of the grating, provide a certain amount of deformation for the sensor, and also provide temperature compensation for the sensor.

[0004] Existing grating load sensors are often difficult to be compatible with both desensitization and temperature compensation, and the structural design is relatively complex. For example, the Chinese patent with publication number CN109900218A provides a fiber grating load sensor with temperature compensation for wind turbine blade monitoring, in which the desensitization structure has no temperature compensation measures. In practical applications, a temperature sensor is usually added next to the load sensor. There is also a way to add double gratings to the structure, which makes the structure more complicated. Utility Model Content

[0005] In order to solve the problems of the prior art, the utility model provides a desensitization load grating sensor, which has a simple structure and has the function of protecting the grating under tensile load, and is compatible with desensitization and temperature compensation.

[0006] The utility model comprises a protective shell composed of a sensor base plate and a sensor cover plate, wherein an elastomer and a grating protective cover are arranged in the protective shell, the elastomer is connected with an optical fiber leading to the outside of the protective shell, the grating area of ​​the optical fiber is fixed on the elastomer, the elastomer is fixed on the sensor base plate, and the deformation direction of the elastomer is opposite to the deformation of the grating.

[0007] As a further improvement, the elastic body is a pair of L-shaped structures connected end to end, the optical fiber passes through the center of the pair of L-shaped structures, the end of the L-shaped structure and the optical fiber parallel section is the elastic body fixing point, and the end of the L-shaped structure and the grating perpendicular section is the optical fiber fixing point.

[0008] As a further improvement, a fiber coiling area is left on the right side of the elastic body.

[0009] Further improvement, assuming that the linear expansion coefficient of the sensor is known k, and the linear expansion coefficient of the sensor base is known K 1 , then the linear expansion coefficient of the elastic body is k 2 Materials,

[0010] The beneficial effects of the utility model are:

[0011] 1. The structural deformation direction of the elastic body in the grating sensor is opposite to the deformation of the grating. This structural design can realize that when the sensor is stretched, the grating is in a compressed state, which has the advantage of protecting the grating under large loads.

[0012] 2. By simultaneously changing the ratio of the grating fixed point distance Lf and the elastic body fixed point distance L, the sensor desensitization ratio can be achieved.

[0013] 3. The overall structure of the sensor is designed in such a way that a fiber coiling area is left on the right side of the elastic body, which can effectively adjust the grating position or serve as a fiber coiling space for optical fiber fusion splicing.

[0014] 4. When the temperature of the sensor rises, the distance between the fixed points of the elastomer increases, and the distance between the fixed points of the elastomer and the fixed points of the grating on a single elastomer also increases. By selecting the temperature expansion coefficient of the elastomer material, the distance between the fixed points of the grating at both ends can be ensured to remain unchanged, thereby achieving the effect of temperature compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0017] Figure 2 This is a cross-sectional view of the internal structure of the utility model;

[0018] Figure 3 This is a working principle diagram of the utility model.

[0019] In the figure, 1 is the sensor base plate, 2 is the elastomer, 3 is the optical fiber, 4 is the grating protection cover, 5 is the sensor cover plate, 6 is the elastomer fixing point, and 7 is the optical fiber fixing point. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] The utility model aims to design a grating load sensor which takes into account both desensitization and temperature compensation. The grating load sensor has a simple structure and can protect the grating under tensile load. A method for designing desensitization and temperature compensation is also provided.

[0022] Utility model principle:

[0023] The sensor elastic body fixing point is glued to the bottom plate, and the optical fiber engraved with the grating is fixed in the optical fiber groove of the elastic body with glue. When the sensor is subjected to tensile load, the distance of the optical fiber fixing point is reduced, thereby effectively protecting the grating. Because the length of the optical fiber fixing point is greater than the length of the elastic body fixing point, under the same deformation, the strain value detected by the grating is less than the actual strain value of the sensor, so the sensor has the effect of reducing the sensitivity. When the temperature of the sensor rises, the distance between the fixing points of the elastic body increases, and the distance from the fixing point of the elastic body to the fixing point of the grating on a single elastic body also increases. By selecting the temperature expansion coefficient of the material, the distance between the grating fixing points at both ends can be guaranteed to remain unchanged, thereby achieving the effect of temperature compensation.

[0024] Core Program:

[0025] A grating load sensor comprises a sensor base plate, an elastic body, an optical fiber (optical cable), a grating protection cover and a sensor cover plate, wherein the grating area of ​​the optical fiber is fixed on the elastic body, and the elastic body is fixed on the sensor base plate.

[0026] as follows Figure 1 As shown, it is a structural diagram of a sensor of the utility model, wherein 1 is a sensor base plate, 2 is an elastic body, 3 is an optical fiber, 4 is a grating protection cover, and 5 is a sensor cover plate.

[0027] as follows Figure 2 The figure shows the internal structure of the sensor, where 6 is the fixing point of the elastic body and 7 is the fixing point of the optical fiber.

[0028] as follows Figure 3 As shown, it is the principle diagram of the sensor, and the distance of the grating fixed point is defined as L f , the distance between the fixed points of the elastic body is L f .

[0029] The principle of desensitization:

[0030] Because the working principle of the sensor is that when the substrate is stretched or compressed by external force, the L-segment substrate undergoes a deformation of ΔL, and the sensor transmits the deformation to the optical fiber, so the optical fiber in the Lf segment also has a deformation of ΔL. The strain of the substrate and the grating can be calculated as follows:

[0031] Substrate strain

[0032] Grating strain

[0033] Because the new structure L<L f , so ε 1 >ε 2 , that is, the strain value detected by the grating of the new structure is smaller than the actual strain value of the substrate, so the structural type of the current sensor is a desensitized sensor.

[0034] The principle of warming:

[0035] Assume that the temperature rise of the structure is ΔC and the linear expansion coefficient of the substrate is K 1 , the linear expansion coefficient of the elastic body is K 2 , the length of a single elastic body is L s . Available,

[0036] The expansion of the substrate is, Δl 1 =L·K 1 ·ΔC

[0037] The expansion of a single elastic body is Δl 2 =L s ·K 2 ·ΔC

[0038] If the grating is to be free of strain when the temperature rises, it is necessary to ensure that L f unchanged. The following equation can be obtained

[0039] 2×(L s +Δl 2 )-(L+Δl 1 )=L f

[0040] Because in the structure,

[0041] Δl 1 , Δl 2 and L s Substituting into the above equation, we can get the following equation

[0042] L.K 1 =(L+L f )·K 2

[0043] make Then there is

[0044]

[0045] If the sensor's k is known and the base material is determined (i.e. K 1 If known), then K can be calculated 2 , thereby confirming the range of elastomer material selection.

[0046] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, the above is only a preferred implementation of the utility model. Since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this. Any technician familiar with the technical field is within the technical scope disclosed by the utility model. For ordinary technicians in the technical field, changes or replacements that can be easily thought of should be included in the protection scope of the utility model without departing from the principle of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A desensitized load grating sensor, comprising a protective housing composed of a sensor base plate and a sensor cover plate, an elastic body and a grating protective cover are arranged in the protective housing, and the elastic body is connected to an optical fiber leading to the outside of the protective housing, characterized in that: The grating region of the optical fiber is fixed on an elastic body, the elastic body is fixed on a sensor bottom plate, and the deformation direction of the elastic body is opposite to the deformation of the grating.

2. The desensitized load grating sensor according to claim 1, characterized in that: The elastic body is a pair of L-shaped structures connected end to end, the optical fiber passes through the center of the pair of L-shaped structures, the end of the L-shaped structure and the optical fiber parallel section is the elastic body fixing point, and the end of the L-shaped structure and the grating perpendicular section is the optical fiber fixing point.

3. The desensitized load grating sensor according to claim 1, characterized in that: A fiber coiling area is left on the right side of the elastic body.

4. The desensitized load grating sensor according to claim 1, characterized in that: Assuming that the linear expansion coefficient of the sensor is known as k, and the linear expansion coefficient of the sensor base is known as K1, the elastic body is selected from a material with a linear expansion coefficient of k2. .

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