Pipeline vibration monitoring device

Abstract

The utility model discloses a pipeline vibration monitoring device, which comprises a first vibration measurement unit, a signal transmission optical cable and an optical fiber regulator, the first vibration measurement unit comprises a clamping assembly, a supporting assembly arranged in the clamping assembly, an elastic assembly arranged in the clamping assembly, a fixing assembly arranged in the clamping assembly and a sensitization assembly. Optical fiber vibration sensors are arranged in the fixing assembly and the sensitization assembly; and the signal transmission optical cable is connected between the first vibration measurement unit and the optical fiber regulator. The optical fiber vibration sensor at the outer bend is subjected to sensitization treatment through the sensitization assembly, vibration of the pipeline is transmitted to the sensitization spring through the elastic assembly, and after being amplified by the sensitization spring, the vibration is monitored by the optical fiber vibration sensor, so that the device is not affected by the inner side and the outer side of the bend, and the purpose that in the bend, the pipeline is not damaged is achieved. The two optical fiber vibration sensors synchronously monitor vibration at the bend, so that the vibration sensing capacity of the two optical fiber vibration sensors is enhanced, and the overall accuracy of the monitoring device is ensured.

Description

TECHNICAL FIELD

[0001] The embodiment of the utility model belongs to the technical field of pipeline vibration monitoring, more particularly, relates to a pipeline vibration monitoring device. BACKGROUND

[0002] The pipeline in the range of power station boiler includes main feed water pipeline, main steam pipeline, reheated steam pipeline and the like. The pipeline in the range of boiler often leads to abnormal vibration due to fast internal working medium flow rate, high pressure, unreasonable pipeline structure arrangement and the like factors. Due to the dramatic increase of new energy installed capacity, the coal-fired unit of power generation boiler will undertake more and more electric power regulation responsibility, leading to the boiler often being in deep peak regulation operation, the pipe medium working condition changing dramatically, the temperature fluctuating dramatically, thereby leading to the pipeline in the range of boiler vibrating dramatically, the pipeline shape deforming, the position moving greatly and the pipeline structure being unstable seriously, finally leading to the pipeline breaking or pipe explosion, which seriously affects the safe operation of unit. It is needed to monitor the vibration of the pipeline in the range of boiler to find the vibration abnormal condition in time, providing safety guarantee for the safe operation of boiler.

[0003] The pipeline vibration signal monitoring method in prior art comprises: obtaining a noisy signal containing pipeline background noise, establishing a deep belief network reflecting the nonlinear mapping relationship of signal parameters and time-frequency mask according to the noisy signal; obtaining an optical signal containing pipeline vibration information, inputting the optical signal into the deep belief network to obtain a sample signal; labeling the sample signal to form a sample data set, establishing a convolutional neural network for fault diagnosis according to the sample data set; collecting an optical signal containing the vibration information of the pipeline to be tested, inputting the optical signal into the deep belief network to obtain a target output result; obtaining a time domain waveform signal corresponding to the target output result, inputting the time domain waveform signal into the convolutional neural network to obtain a target monitoring result, and completing the pipeline vibration signal monitoring. The vibration of the pipeline is monitored.

[0004] However, since there is an elbow in the pipeline, the speed of the fluid in the inner side of the elbow is usually high, and the fluid flows along the inner wall to form a large shear force and turbulence, so that the vibration intensity generated at the inner bend and the outer bend is inconsistent, which leads to that it is difficult to effectively analyze the vibration condition monitored by the sensor when monitoring the same, and the monitoring data at the elbow is particularly important. Therefore, a pipeline vibration monitoring device is needed to monitor the elbow of the pipeline and provide effective monitoring data. UTILITY MODEL CONTENT

[0005] In view of the above defects or improvement needs of the prior art, the pipeline vibration monitoring device sensitizes the optical fiber vibration sensor at the outer bend through a sensitizing assembly, transmits the vibration of the pipeline to the sensitizing spring through an elastic assembly, and is monitored by the optical fiber vibration sensor after being amplified by the sensitizing spring, so that the device is not affected by the inner and outer sides of the bend, the two optical fiber vibration sensors are used to synchronously monitor the vibration at the bend in the inner bend and the outer bend, the vibration sensing capability is enhanced, and the accuracy of the whole monitoring device is ensured.

[0006] In order to achieve the above purpose, the pipeline vibration monitoring device provided by the embodiments of the utility model comprises a first vibration measuring unit, a signal transmission optical cable and an optical fiber adjusting instrument.

[0007] The first vibration measuring unit comprises a clamping assembly, a supporting assembly arranged in the clamping assembly, an elastic assembly arranged in the clamping assembly, a fixing assembly arranged in the clamping assembly and a sensitizing assembly.

[0008] The fixing assembly and the sensitizing assembly are provided with an optical fiber vibration sensor.

[0009] The signal transmission optical cable is connected between the first vibration measuring unit and the optical fiber adjusting instrument.

[0010] Further, the clamping assembly comprises a clamping upper plate and a clamping lower plate, and the pipeline bend is wrapped therebetween through a bolt.

[0011] Further, a plurality of elastic assemblies are arranged between the clamping assembly and the pipeline, so that the clamping assembly and the pipeline are connected.

[0012] The elastic assembly comprises an inner elastic base in contact with the pipeline, an outer elastic base arranged on the inner wall of the clamping upper plate and the clamping lower plate, and an air spring arranged between the inner elastic base and the outer elastic base.

[0013] The outer elastic base is fixedly connected between the clamping upper plate and the clamping lower plate, and the inner elastic base is pushed on the outer wall of the pipeline through the air spring.

[0014] Further, the supporting assembly is arranged on the inner wall of the clamping upper plate and located directly above the clamping upper plate, and comprises an inner arc plate in contact with the pipeline, an outer arc plate arranged on the inner wall of the clamping upper plate, and a supporting rod arranged between the inner arc plate and the outer arc plate.

[0015] Further, one side of the inner arc plate close to the pipeline is an arc surface, which is attached to and fixed on the outer wall of the pipeline, and one side of the outer arc plate close to the clamping upper plate is also an arc surface, which is attached to and fixed on the inner wall of the clamping upper plate.

[0016] The side of the outer arc plate close to the pipeline is also arc, and a groove is arranged in the arc, and a sliding plate is fixed in the groove, and the outer arc plate extends downward around the sliding plate to form a baffle;

[0017] The support rod is fixed at one end to the inner arc plate, and a wear plate is fixed at the other end.

[0018] Further, the fixing assembly is arranged close to the inner side of the pipeline, and comprises a fixing rod arranged on the clamping upper plate and the clamping lower plate.

[0019] Further, the front end of the fixing rod is an arc plate, and the arc plates of the two fixing rods are folded after being spliced with the clamping upper plate and the clamping lower plate to form a fixing groove with a circular inner space.

[0020] The fixing assembly is arranged along the inner side of the pipeline, and a plurality of fixing assemblies are arranged along the curvature of the pipeline at equal intervals, and the fiber vibration sensor is arranged in the fixing groove of the plurality of fixing assemblies after being slightly bent.

[0021] Further, the sensitizing assembly is arranged close to the outer side of the pipeline, and comprises a sensitizing seat and a sensitizing plate arranged at the joint of the clamping upper plate and the clamping lower plate, a sensitizing groove arranged on the sensitizing seat, and a sensitizing spring arranged between the sensitizing seat and the sensitizing groove.

[0022] Further, the sensitizing seat is arranged on the clamping upper plate close to the outer side, and extends downward to a position at which the sensitizing groove and the fixing groove are at the same height.

[0023] The sensitizing plate is arranged on the clamping lower plate close to the outer side, and a reinforcing plate is further arranged between the sensitizing plate and the clamping lower plate to provide support for the sensitizing seat.

[0024] The sensitizing assembly is arranged along the outer side of the pipeline, and a plurality of fixing assemblies are arranged along the curvature of the pipeline at equal intervals, and the fiber vibration sensor is arranged in the sensitizing groove of the plurality of sensitizing assemblies after being slightly bent.

[0025] Further, the sensitizing groove is further provided with an adjusting rope, one end of the adjusting rope passes through the sensitizing seat, and a rope clamp is arranged at the end passing through the sensitizing seat, the length of the sensitizing spring is changed by pulling the adjusting rope, and the rope clamp is used to maintain the length.

[0026] Overall, compared with the prior art, the above technical scheme of the utility model can achieve the following beneficial effects:

[0027] 1.The monitoring device of the utility model, the fiber optic vibration sensor of outer bending place carries out sensitization treatment through the sensitization component, the vibration of pipeline is transmitted to the sensitization spring through the elastic component, after being amplified by the sensitization spring, is monitored to the fiber optic vibration sensor, makes the device not to be influenced by the two sides of the inside and outside of the curve, realizes in the inside and outside of the curve, two fiber optic vibration sensors carry out synchronous monitoring to the vibration of the curve, makes its inductive vibration ability enhance, ensures the accuracy of monitoring device whole.

[0028] 2.The monitoring device of the utility model, the vibration condition of pipe elbow is monitored by using the first vibration measuring unit, the vibration condition of pipe support is monitored by the second vibration measuring unit, the actual situation of pipeline vibration is obtained through the analysis of the monitoring results of two vibration measuring units, to remind the manager pipeline vibration state, thereby reducing the operation risk of depth peak shaving.

[0029] 3.The monitoring device of the utility model, the elasticity of air spring can be fully contacted with the pipeline of different pipe diameter, and when the pipeline vibrates, the clamping assembly is vibrated under the action of air spring, so that it is monitored by the fiber optic vibration sensor, and the monitoring of pipeline vibration is realized.

[0030] 4.The monitoring device of the utility model, the first vibration measuring unit is supported on the pipeline by the supporting assembly, prevents its from falling due to its own gravity, causes the weakening of the effect of elastic component, and the sliding connection between the supporting rod and the outer arc plate is realized, when the pipeline vibrates, the clamping assembly is not constrained, and the monitoring effect of pipeline vibration is ensured. DRAWINGS

[0031] Figure 1 It is the overall structure schematic view of a pipeline vibration monitoring device of the utility model embodiment;

[0032] Figure 2 It is the structure schematic view of the first vibration measuring unit of a pipeline vibration monitoring device of the utility model embodiment;

[0033] Figure 3 It is the structure schematic view of the first vibration measuring unit of a pipeline vibration monitoring device of the utility model embodiment; Figure 2

[0034] Figure 4 It is the structure schematic view of the first vibration measuring unit of a pipeline vibration monitoring device of the utility model embodiment; Figure 3

[0035] Figure 5 It is the structure schematic view of the first vibration measuring unit of a pipeline vibration monitoring device of the utility model embodiment; Figure 3

[0036] Figure 6 It is the structure schematic view of the second vibration measuring unit of a pipeline vibration monitoring device of the utility model embodiment.

[0037] ​​​In all the drawings, the same reference signs represent the same technical features, specifically: 1 - first vibration measuring unit, 11 - clamping assembly, 111 - clamping upper plate, 112 - clamping lower plate, 12 - support assembly, 121 - inner arc plate, 122 - outer arc plate, 123 - support rod, 124 - sliding plate, 13 - fixing assembly, 131 - fixing rod, 132 - fixing groove, 14 - elastic assembly, 141 - inner elastic base, 142 - outer elastic base, 143 - air spring, 15 - sensitization assembly, 151 - sensitization seat, 152 - sensitization plate, 153 - sensitization spring, 154 - adjusting rope, 155 - sensitization groove, 2 - second vibration measuring unit, 21 - support plate, 22 - longitudinal support rod, 23 - transverse support rod, 24 - support groove, 3 - signal transmission optical cable, 4 - optical fiber adjusting instrument. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model and not to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0039] As shown in Figure 1 , the utility model embodiment provides a pipeline vibration monitoring device, which comprises a first vibration measuring unit 1 arranged at a pipeline bend, a second vibration measuring unit 2 arranged at a pipeline support, a signal transmission optical cable 3 and an optical fiber adjusting instrument 4. The first vibration measuring unit 1 is used for monitoring the vibration condition at the pipeline bend, and the second vibration measuring unit 2 is used for monitoring the vibration condition at the pipeline support. By analyzing the monitoring results of the two vibration measuring units, the actual condition of pipeline vibration can be obtained to remind the manager of the pipeline vibration state, thereby reducing the operation risk of deep peak shaving.

[0040] As shown in Figure 2 , 3 , the first vibration measuring unit 1 comprises a clamping assembly 11, a support assembly 12 arranged in the clamping assembly 11, an elastic assembly 14 arranged in the clamping assembly 11, a fixing assembly 13 arranged in the clamping assembly 11 and a sensitization assembly 15. The fixing assembly 13 and the sensitization assembly 15 are provided with optical fiber vibration sensors for real-time monitoring of the vibration of the pipeline.

[0041] The clamping assembly 11 has the same curvature as the pipe bend, and the entire first vibration measuring unit 1 is fixed to the pipe bend through the clamping assembly 11. The clamping assembly 11 includes a clamping upper plate 111 and a clamping lower plate 112, and the clamping upper plate 111 and the clamping lower plate 112 are fixed by bolts to wrap the pipe therebetween, thereby realizing the connection between the first vibration measuring unit 1 and the pipe.

[0042] The elastic assembly 14 is provided between the clamping assembly 11 and the pipe, and the clamping assembly 11 is connected to the pipe, including an inner elastic base 141 in contact with the pipe, an outer elastic base 142 provided on the inner wall of the clamping upper plate 111 and the clamping lower plate 112, and an air spring 143 provided between the inner elastic base 141 and the outer elastic base 142. The outer elastic base 142 is fixedly connected between the clamping upper plate 111 and the clamping lower plate 112, and the inner elastic base 141 is pushed against the outer wall of the pipe through the air spring 143. The air spring 143 can be in complete contact with pipes of different diameters through the elastic force, and when the pipe vibrates, the clamping assembly 11 vibrates under the action of the air spring 143, which is monitored by the fiber optic vibration sensor, thereby realizing the monitoring of the pipe vibration.

[0043] As shown in Figure 4 The support assembly 12 is provided on the inner wall of the clamping upper plate 111 and located directly above the clamping upper plate 111, and includes an inner arc plate 121 in contact with the pipe, an outer arc plate 122 provided on the inner wall of the clamping upper plate 111, and a support rod 123 provided between the inner arc plate 121 and the outer arc plate 122. The side of the inner arc plate 121 close to the pipe is arc-shaped, which is fitted and fixed to the outer wall of the pipe. The side of the outer arc plate 122 close to the clamping upper plate 111 is also arc-shaped, which is fitted and fixed to the inner wall of the clamping upper plate 111. The side of the outer arc plate 122 close to the pipe is also arc-shaped, and a groove is provided in the arc-shaped surface, and a sliding plate 124 is fixed in the groove. The outer arc plate 122 extends downward around the sliding plate 124 and is provided with a baffle. The support rod 123 is provided with a wear-resistant plate on the end, and the wear-resistant plate slides and rubs between the sliding plate 124. The first vibration measuring unit 1 is supported on the pipe by the support assembly 12 to prevent it from falling due to its own gravity, which weakens the effect of the elastic assembly 14. At the same time, the support rod 123 and the outer arc plate 122 are connected by sliding, and when the pipe vibrates, the clamping assembly 11 is not constrained, thereby ensuring the monitoring effect of the pipe vibration.

[0044] The fixing assembly 13 is arranged near one side of the inner side bend of the pipeline, and includes fixing rods 131 arranged on the clamping upper plate 111 and the clamping lower plate 112. The front ends of the fixing rods 131 are arc-shaped plates, and the arc-shaped plates of the two fixing rods 131 are folded after being spliced with the clamping upper plate 111 and the clamping lower plate 112, to form a fixing groove 132 with a circular inner space. The fixing assembly 13 is arranged in plurality along the inner side bend, and the plurality of fixing assemblies 13 are arranged equidistantly along the curvature of the bend. The fiber optic vibration sensor is arranged in the fixing groove 132 of the plurality of fixing assemblies 13 after being slightly bent.

[0045] Since the speed of the fluid in the pipeline is usually high on the inner side of the bend, the fluid flows along the inner wall to form a large shear force and a turbulent flow, so that the vibration intensities generated at the inner bend and the outer bend are inconsistent. In this case, monitoring the vibration at the bend will produce a certain error, and therefore the fiber optic vibration sensor at the outer bend needs to be sensitized by the sensitizing assembly 15 to enhance the sensing capability, so as to ensure the accuracy of the monitoring device as a whole.

[0046] As shown in Figure 5 The sensitizing assembly 15 is arranged near one side of the outer side bend of the pipeline, and includes a sensitizing seat 151 and a sensitizing plate 152 arranged at the connection between the clamping upper plate 111 and the clamping lower plate 112, a sensitizing groove 155 arranged on the sensitizing seat 151, and a sensitizing spring 153 arranged between the sensitizing seat 151 and the sensitizing groove 155. The sensitizing seat 151 is arranged on one side of the clamping upper plate 111 near the outer bend, and extends downward to a position at which the sensitizing groove 155 is at the same height as the fixing groove 132, so as to ensure that the sensitizing seat 151 is located on the front side of the bend, and facilitate the analysis of the monitored data. The sensitizing plate 152 is arranged on one side of the clamping lower plate 112 near the outer bend, and a reinforcing plate is further arranged between the sensitizing plate 152 and the clamping lower plate 112, to provide support for the sensitizing seat 151, so as to prevent the sensitizing seat 151 from shaking due to its own material and affecting the monitoring result. The sensitizing assembly 15 is arranged in plurality along the outer side bend, and the plurality of fixing assemblies 13 are arranged equidistantly along the curvature of the bend. The fiber optic vibration sensor is arranged in the sensitizing groove 155 of the plurality of sensitizing assemblies 15 after being slightly bent.

[0047] The vibration of the pipeline is transmitted to the sensitizing spring 153 through the elastic assembly 14, and is amplified by the sensitizing spring 153, so as to be monitored by the fiber optic vibration sensor. In this way, the device is not affected by the inner side and the outer side of the bend, and the two fiber optic vibration sensors can synchronously monitor the vibration at the bend.

[0048] The bottom of the sensitizing groove 155 is also provided with an adjusting rope 154, one end of which passes through the sensitizing seat 151 and is provided with a rope clamp at the end passing through the sensitizing seat 151. The length of the sensitizing spring 153 is changed by pulling the adjusting rope 154, and the rope clamp is used to maintain the length. By changing the compression degree of the sensitizing spring 153, the sensitivity is adjusted, so that the sensitizing performance of the sensitizing assembly 15 meets the actual requirements.

[0049] As shown in Figure 6 The second vibration measuring unit 2 comprises a support plate 21 arranged on a pipeline support, longitudinal support rods 22 and horizontal support rods 23 arranged in the support plate 21, and support grooves 24 arranged at the front ends of the longitudinal support rods 22 and the horizontal support rods 23. The support grooves 24 are also provided with optical fiber vibration sensors.

[0050] The signal transmission optical cable 3 connects the first vibration measuring unit 1 and the second vibration measuring unit 2 with the optical fiber adjusting instrument 4 respectively, and transmits the collected vibration signals to the optical fiber adjusting instrument 4.

[0051] The optical fiber adjusting instrument 4 is used for exciting the light source of the optical fiber vibration sensor, simultaneously receiving the broadcast signal with vibration information, and realizing the analysis and display of the signal.

[0052] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pipeline vibration monitoring device, characterized in that: include: A first vibration measuring unit (1), a signal transmission optical cable (3), and an optical fiber adjuster (4); The first vibration measuring unit (1) comprises a clamping assembly (11), a supporting assembly (12) provided in the clamping assembly (11), an elastic assembly (14) provided in the clamping assembly (11), a fixing assembly (13) provided in the clamping assembly (11), and a sensitivity enhancement assembly (15); Optical fiber vibration sensors are provided in the fixing component (13) and the sensitivity enhancement component (15); The signal transmission optical cable (3) is connected between the first vibration measuring unit (1) and the optical fiber regulator (4).

2. A pipeline vibration monitoring device according to claim 1, characterized in that: The clamping assembly (11) comprises a clamping upper plate (111) and a clamping lower plate (112), which are fixed by bolts to wrap the bend of the pipeline.

3. A pipeline vibration monitoring device according to claim 2, characterized in that: A plurality of elastic components (14) are provided between the clamping component (11) and the pipeline, so as to realize connection between the clamping component (11) and the pipeline; It comprises an inner elastic base (141) in contact with the pipeline, an outer elastic base (142) provided on the inner walls of the clamping upper plate (111) and the clamping lower plate (112), and an air spring (143) provided between the inner elastic base (141) and the outer elastic base (142); The outer elastic base (142) is fixedly connected to the clamping upper plate (111) and the clamping lower plate (112), and the inner elastic base (141) is pushed against the outer wall of the pipeline via an air spring (143).

4. A pipeline vibration monitoring device according to claim 3, characterized in that: The support assembly (12) is arranged on the inner wall of the clamping upper plate (111) and is located directly above the clamping upper plate (111). The support assembly (12) includes an inner arc plate (121) in contact with the pipeline, an outer arc plate (122) arranged on the inner wall of the clamping upper plate (111), and a support rod (123) arranged between the inner arc plate (121) and the outer arc plate (122).

5. A pipeline vibration monitoring device according to claim 4, characterized in that: The side of the inner arc plate (121) close to the pipe is a curved surface, which fits the outer wall of the pipe and is fixed thereon; the side of the outer arc plate (122) close to the clamping upper plate (111) is also a curved surface, which fits the inner wall of the clamping upper plate (111) and is fixed thereon; The side of the outer arc plate (122) close to the pipe is also an arc surface, and a groove is provided in the arc surface, and a slide plate (124) is fixed in the groove. The outer arc plate (122) is provided with a baffle extending downward around the slide plate (124); There are multiple support rods (123), one end of which is fixed on the inner arc plate (121), and a wear-resistant plate is fixed on the end of the other end, and there is sliding friction between the wear-resistant plate and the slide plate (124).

6. A pipeline vibration monitoring device according to any one of claims 2 to 5, characterized in that: The fixing assembly (13) is arranged on a side close to the inner bend of the pipeline, and comprises a fixing rod (131) arranged on the clamping upper plate (111) and the clamping lower plate (112).

7. A pipeline vibration monitoring device according to claim 6, characterized in that: The front end of the fixing rod (131) is an arc-shaped plate. The arc-shaped plates of the two fixing rods (131) are joined together with the clamping upper plate (111) and the clamping lower plate (112) to form a fixing groove (132) with a circular internal space. A plurality of the fixing components (13) are arranged along the inner curve, and the plurality of fixing components (13) are arranged equidistantly along the curvature of the curve. The optical fiber vibration sensor is arranged in the fixing grooves (132) of the plurality of fixing components (13) after being slightly bent.

8. A pipeline vibration monitoring device according to any one of claims 2 to 5, characterized in that: The sensitivity enhancement component (15) is arranged on a side close to the outer bend of the pipeline, and comprises a sensitivity enhancement seat (151) and a sensitivity enhancement plate (152) arranged at the connection between the clamping upper plate (111) and the clamping lower plate (112), a sensitivity enhancement groove (155) arranged on the sensitivity enhancement seat (151), and a sensitivity enhancement spring (153) arranged between the sensitivity enhancement seat (151) and the sensitivity enhancement groove (155).

9. The pipeline vibration monitoring device according to claim 8, characterized in that: The sensitivity enhancement seat (151) is arranged on a side of the clamping upper plate (111) close to the outer bend, and extends downward to a position where the sensitivity enhancement groove (155) and the fixing groove (132) are at the same height; The sensitivity enhancement plate (152) is arranged on the side of the clamping lower plate (112) close to the outer bend, and a reinforcement plate is provided between the sensitivity enhancement plate (152) and the clamping lower plate (112) to provide support for the sensitivity enhancement seat (151); The sensitivity enhancement components (15) are arranged in plurality along the outer bend, and the plurality of fixed components (13) are arranged equidistantly along the curvature of the bend. The optical fiber vibration sensor is arranged in the sensitivity enhancement grooves (155) of the plurality of sensitivity enhancement components (15) after being slightly bent.

10. The pipeline vibration monitoring device according to claim 9, characterized in that: An adjusting rope (154) is further provided at the bottom of the sensitivity enhancement groove (155). One end of the adjusting rope (154) passes through the sensitivity enhancement seat (151), and a rope clamp is provided at the other end passing through the sensitivity enhancement seat (151). The length of the sensitivity enhancement spring (153) is changed by pulling the adjusting rope (154), and the rope clamp is used to maintain the length.

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