Screw-type magnetoresistive sensor for main coolant pump and measurement method thereof

Abstract

It includes a sensor body, which includes a connector and a probe. The sensor body is fixed on a bracket located on a pump housing through a nut. The connector includes a protective tube, a locking sleeve, a rubber ring and a clamping cap. The clamping cap is embedded in the locking sleeve, and the rubber ring is embedded in the tail of the protective tube. The clamping cap is connected to the tail of the protective tube through a thread. The connecting sleeve is inserted into the protective tube and connected to the housing through a thread. The housing is provided with a probe, a connecting wire, a socket and an insulator. One end of the connecting wire is connected to the probe, and the other end of the connecting wire is connected to the socket. The insulator is connected to the housing through a thread. The socket is connected to the insulator through a screw. The probe, the connecting wire, the socket and the insulator are epoxy-encapsulated in the housing. The present invention adopts an end-mounted screw-type magnetoresistive speed sensor to ensure the safe operation of the main coolant pump. A signal enhancement block is added at the end of the signal transmitting tooth to ensure that the sensor can accurately receive the speed signal of the speed transmitting tooth.

Description

Technical Field

[0001] The invention relates to the technical field of rotating machine speed measurement, and in particular to a screw-type magnetic resistance sensor for a main coolant pump and a measurement method thereof. Background Art

[0002] Rotating machinery speed measurement is a conventional monitoring and protection instrument for rotating machinery. The speed measurement and control of rotating machinery is one of the necessary monitoring parameters to ensure the safe operation of rotating machinery. If the speed parameter monitoring fails, it may cause the speed of the rotating machinery to lose control, resulting in the unit stalling, overspeeding or even running away, causing major equipment damage accidents. Therefore, large rotating machinery is usually equipped with a speed measuring device to monitor the speed of the rotating machinery. When the speed of the unit exceeds a certain set speed value, the speed monitoring instrument will send an overspeed signal to force the unit to stop to ensure the safety of the unit. The usual speed measurement method: install a speed measuring gear plate (or groove, convex key) on the main shaft of the rotating machinery, install a speed sensor in the radial direction of the speed gear plate, and fix the speed sensor on the bearing seat of the rotating machinery. The speed sensors that can be selected are: eddy current displacement sensor, magnetoresistive speed sensor, Hall sensor, inductive sensor, proximity switch, etc. The sensor senses the speed electrical signal of the rotating machinery, and after the signal processing of the tachometer, the speed measurement and control are realized.

[0003] A large number of rotating machinery are also used in nuclear power plants, such as various pump shafts and pump groups, various large motors, etc., so their speed parameters must also be monitored to ensure the safe operation of the rotating machinery and prevent the rotating machinery from overspeeding, thereby causing damage to the unit.

[0004] The speed measurement of rotating machinery used in nuclear power plants is very different from that of ordinary rotating machinery. Since these rotating machinery are installed in the containment of nuclear power plants, their geographical location is in an environment with long-term radiation exposure, and there are external radiation such as gamma rays, beta rays, and x-rays, and internal radiation of radioactive floating objects such as protium, deuterium, and tritium, and there are many very complex radioactive isotopes. When ordinary sensors work in a radiation environment, it will accelerate the aging of components in the sensor and cause early damage to the sensor. Therefore, sensors used in a radiation environment need to be specially designed and must have radiation resistance. In the reactor main coolant pump of a pressurized water reactor nuclear power plant, due to the structural reasons of the equipment itself, a speed measuring gear plate, groove, convex key and other measuring accessories are not allowed to be installed on the main shaft of the pump shaft. Only a mechanical connecting rod type metal sheet can be installed on the main shaft of the main coolant pump as the transmitting tooth of the main coolant pump speed transmitting device. The speed sensor receives the position signal of the transmitting tooth, and the speed sensor converts the physical quantity of the position of the main coolant pump speed transmitting tooth into an electrical signal output. The output signal of the sensor is a pulse signal, and the frequency of the pulse signal reflects the speed of the main coolant pump. The speed measuring device measures the signal from the speed sensor through signal filtering and amplification, Schmidt trigger shaping, pulse counting and other signal measurements to accurately measure the speed of the main coolant pump.

[0005] The main coolant pump is a vertical pump. The commonly used measurement diagram for its speed measurement is as follows: Figure 1 As shown in the figure, the size of the signaling tooth is: width × thickness × length = 4 × 2.5 × 20mm. When the main coolant pump rotates, it drives a mechanical connecting rod type main coolant pump speed signaling tooth fixed on the pump shaft to rotate. When the signaling tooth passes through the groove of the horseshoe-shaped speed sensor, the internal magnetic resistance of the sensor changes, so that the sensor outputs a speed signal. For its principle diagram, see Figure 2 , the magnetoresistive sensor is composed of a permanent magnet (i.e., magnetic steel), pure iron, an induction coil, etc. The permanent magnet establishes a constant magnetic field, and the magnetic field passes through the induction coil through pure iron (extended magnetic circuit) to form a closed magnetic circuit. The speed sensor must be installed radially, facing a speed measuring gear, which is fixed on the main shaft of the pump shaft. When the pump shaft rotates, when the speed measuring gear passes through the sensor surface, it will change the spatial distribution density of the magnetic lines of force. When the speed sensor faces the tooth valley of the gear, the speed sensor is in a high magnetic resistance state at this time, and the pump shaft rotation drives the gear to rotate. When the speed sensor faces the tooth top of the gear, the speed sensor is in a low magnetic resistance state at this time. The change in the spatial distribution density of the magnetic lines of force will change the magnetic flux in the sensor, and an induced alternating voltage can be generated in the measuring coil. The voltage amplitude is a single-valued function of the installation gap and the linear speed, and the frequency of the induced alternating signal is synchronized with the speed of the gear.

[0006] At present, in my country's nuclear power plants, the speed measurement of the main coolant pump uses imported products. The width of the horseshoe-shaped speed sensor groove is 6.5mm. Figure 1 As shown, in static installation, the installation clearance is: (6.5-2.5) / 2=2mm. Considering the installation error, the installation clearance of the sensor is based on the installation requirements of the product manufacturer. The allowable static installation clearance is: 2±0.5mm. In actual use, although the installation and commissioning are strictly carried out according to the installation manufacturer's requirements, the vertical pump has axial stringing of the pump shaft during operation, and there are multiple dynamic and static frictions between the signaling teeth and the sensor, causing damage to the signaling teeth or the sensor, which seriously affects the safe operation of the main coolant pump. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a screw-type magnetoresistive sensor for a main coolant pump and a measurement method thereof to solve the speed measurement of the main coolant pump of a pressurized water reactor nuclear power plant reactor and ensure the safe operation of the main coolant pump main equipment.

[0008] The object of the present invention is achieved in that:

[0009] A screw-type magnetic resistance sensor for a main coolant pump, comprising a sensor body, the sensor body comprising a connector and a probe, the sensor body being fixed on a bracket located on a pump housing through a nut, the connector comprising a protective tube, a locking sleeve, a rubber ring and a clamping cap; the clamping cap is embedded in the locking sleeve, the rubber ring is embedded in the tail of the protective tube, the clamping cap is connected to the tail of the protective tube through a thread, the connecting sleeve is inserted into the protective tube, and is connected to the housing through a thread;

[0010] The shell is provided with a probe, a connecting wire, a socket and an insulator, one end of the connecting wire is connected to the probe, the other end of the connecting wire is connected to the socket, the insulator is connected to the shell through a thread, the socket is connected to the insulator through a screw, and the probe, connecting wire, socket and insulator are epoxy-encapsulated in the shell.

[0011] Furthermore, the socket is a BNC socket.

[0012] Furthermore, the sensor housing is made of 304 stainless steel.

[0013] Furthermore, the insulator used is made of PEEK material.

[0014] Furthermore, the outer shell is connected to the protective tube via a connecting sleeve.

[0015] A method for measuring a screw-type magnetoresistive sensor for a main coolant pump uses the screw-type magnetoresistive sensor as described above and radially installs it on the main shaft of the main cooling pump of a rotating machine, that is, the sensor installation direction is perpendicular to the main shaft of the main cooling pump and is installed parallel to the installation sleeve of the pump shaft. A signal transmitting tooth is arranged on the pump shaft in a direction perpendicular to the main axis.

[0016] Furthermore, a signal enhancement block is provided at the end of the signal transmitting tooth.

[0017] Furthermore, the signal enhancement block is a 20 mm measurement block.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention adopts an end-mounted screw-type magnetoresistive speed sensor with good radiation resistance. The sensor housing is made of 304 stainless steel, the insulator is made of PEEK material, and the socket is a BNC socket. The assembled parts are sealed in the housing by epoxy resin. The overall mechanical strength is high and the sealing performance is reliable. The protection level is IP56. After adopting this installation method, the axial stringing of the main coolant pump will not occur. Figure 1 The dynamic and static friction between the signal transmitting teeth and the sensor caused by the installation method will not cause damage to the signal transmitting teeth or the sensor, thus ensuring the safe operation of the main coolant pump.

[0020] (2) The present invention adds a signal enhancement block at the end of the signal-transmitting tooth, and increases the local thickness of the end of the signal-transmitting tooth from 2.5 mm to 20 mm, so as to prevent the speed signal-transmitting tooth from deviating from the original installation position along with the pump shaft, so that the speed sensor cannot sense the signal of the speed signal-transmitting tooth, thereby causing inaccurate measurement or failure to measure the speed signal. Since the probe diameter of the screw-type magnetic resistance speed sensor is Φ16 mm, it is aimed at the 20 mm measuring block, ensuring that when the main coolant pump undergoes axial stringing, the speed sensor can also accurately receive the speed signal of the speed signal-transmitting tooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The schematic diagram of the speed measurement installation of the main coolant pump of the reactor in an existing pressurized water reactor nuclear power plant is shown in FIG.

[0022] Figure 2 It is a schematic diagram of the principle of an existing magnetoresistive speed sensor.

[0023] Figure 3 It is a structural schematic diagram of the screw-type magnetoresistive speed sensor of the present invention.

[0024] Figure 4 This is a schematic diagram of the rotation speed measurement installation of Example 1 of the present invention.

[0025] Figure 5This is a schematic diagram of the rotation speed measurement installation of Example 2 of the present invention.

[0026] Figure 6 This is a schematic diagram of the principle of the rotation speed sensor according to Embodiment 2 of the present invention.

[0027] in:

[0028] Main cooling pump main shaft 1, signal transmitting tooth 2, sensor body 3, connector 31, protection tube 311, locking sleeve 312, rubber ring 313, compression cap 314, probe 32, epoxy 33, connecting wire 34, housing 35, insulator 36, screw 37, socket 38, connecting sleeve 39. DETAILED DESCRIPTION

[0029] In order to better understand the technical solution of the present invention, the following will be described in detail in conjunction with the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention, and are only implementations that can be adopted by the technical solution of the present invention. It should be noted that the description of the positional relationship of each component in this article, such as component A being located above component B, is based on the description of the relative positions of the components in the illustration, and is not intended to limit the actual positional relationship of the components.

[0030] Example 1

[0031] See also Figure 3 The present invention relates to a screw-type magnetoresistive sensor for a main coolant pump, which includes a sensor body 3, the sensor body 3 includes a connector 31 and a probe 32, the connector 31 includes a protection tube 311, a locking sleeve 312, a rubber ring 313 and a clamping cap 314; the clamping cap 314 is embedded in the locking sleeve 312, the rubber ring 313 is embedded in the tail of the protection tube 311, the clamping cap 314 is connected to the tail of the protection tube 311 through a thread, and the connecting sleeve 39 is inserted into the protection tube 311 and connected to the housing 35 through a thread;

[0032] The housing 35 is provided with a probe 32, a connecting wire 34, a socket 38 and an insulator 36. One end of the connecting wire 34 is connected to the probe 32, and the other end of the connecting wire 34 is connected to the socket 38. The insulator 36 is connected to the housing 35 via a thread, and the socket 38 is connected to the insulator 36 via a screw 37. The probe 32, the connecting wire 34, the socket 38 and the insulator 36 are encapsulated in the housing 35 with epoxy 33.

[0033] The sensor housing 35 is made of 304 stainless steel, the connector 38 is a BNC connector, and the assembled parts are sealed in the housing 35 by epoxy 33 glue. The overall mechanical strength is high, the sealing performance is reliable, and the protection level is IP56.

[0034] See also Figure 4 , Figure 4The figure shows a schematic diagram of the rotation speed measurement installation of the sensor of this embodiment. As shown in the figure, the present invention relates to a measurement method of a screw-type magnetic resistance sensor for a main coolant pump, which includes the following contents:

[0035] The screw-type magnetoresistive sensor as described above is radially installed on the main cooling pump main shaft 1 of the rotating machinery, that is, the sensor installation direction is perpendicular to the main cooling pump main shaft 1, and a signal transmitting tooth 2 is arranged on the pump shaft 1 in a direction perpendicular to the main axis.

[0036] Example 2

[0037] See also Figure 5 The present invention relates to a method for measuring a screw-type magnetoresistive sensor for a main coolant pump. The difference from the first embodiment is that the second embodiment is provided with a signal enhancement block 4 at the end of the signal transmitting tooth 2, and the signal enhancement block 4 is a 20 mm measuring block. Since the probe diameter of the screw-type magnetoresistive speed sensor is Φ16 mm, the 20 mm measuring block ensures that when the main coolant pump is axially skewing, the speed sensor can also accurately receive the speed signal of the speed transmitting tooth.

[0038] Working principle:

[0039] See also Figure 6 When the speed sensor is not facing the speed signaling tooth, the speed sensor is in a high magnetic resistance state, and the pump shaft rotation drives the signaling tooth to rotate. When the speed sensor faces the improved signaling tooth, the speed sensor is in a low magnetic resistance state. The change in the spatial distribution density of magnetic lines of force will change the magnetic flux in the sensor, and an induced alternating voltage can be generated in the measuring coil. The voltage amplitude is a single-valued function of the installation gap and the linear speed, and the induced alternating signal frequency is synchronized with the speed of the gear.

[0040] The above are only specific application examples of the present invention and do not constitute any limitation on the protection scope of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. A screw-type magnetoresistive sensor for a main coolant pump, characterized in that: The screw-type magnetoresistive sensor is radially mounted on a main cooling pump main shaft (1) of a rotating machine, the mounting direction of the screw-type magnetoresistive sensor being perpendicular to the main axis of the main cooling pump main shaft (1), and a signal transmitting tooth (2) is provided on the main cooling pump main shaft (1) in a direction perpendicular to the main axis; The screw-type magnetoresistive sensor comprises a sensor body (3), the sensor body (3) comprises a connector (31) and a probe (32), the connector (31) comprises a protective tube (311), a locking sleeve (312), a rubber ring (313) and a clamping cap (314); the clamping cap (314) is embedded in the locking sleeve (312), the rubber ring (313) is embedded in the rear end of the protective tube (311), the clamping cap (314) is connected to the rear end of the protective tube (311) via a thread, and the connecting sleeve (39) is inserted into the protective tube (311) and connected to the housing (35); The housing (35) is provided with a probe (32), a connecting wire (34), a socket (38) and an insulator (36); one end of the connecting wire (34) is connected to the probe (32); the other end of the connecting wire (34) is connected to the socket (38); the insulator (36) is connected to the housing (35); the socket (38) is connected to the insulator (36) via a screw (37); the probe (32), the connecting wire (34), the socket (38) and the insulator (36) are encapsulated in the housing (35) by epoxy (33); A signal enhancement block (4) is provided at the end of the signal transmitting tooth (2) facing the sensor body (3); Along the vertical direction of the main axis of the main cooling pump main shaft (1), there is a gap between the signal enhancement block (4) and the sensor body (3); Along the vertical direction of the main axis of the main cooling pump main shaft (1), the signal enhancement block (4) is arranged opposite to the sensor body (3); Along the direction of the main axis of the main cooling pump main shaft (1), the end surface dimension of the signal enhancement block (4) facing the sensor body (3) is larger than the end surface dimension of the sensor body (3) facing the signal enhancement block (4).

2. A screw-type magnetoresistive sensor for a main coolant pump according to claim 1, characterized in that: The socket (38) is a BNC socket.

3. A screw-type magnetoresistive sensor for a main coolant pump according to claim 1, characterized in that: The sensor housing (35) is made of 304 stainless steel.

4. A screw-type magnetoresistive sensor for a main coolant pump according to claim 1, characterized in that: The insulator is made of PEEK material.

5. The screw-type magnetoresistive sensor for a main coolant pump according to claim 1, characterized in that: The housing (35) is connected to the protection tube (311) via a connecting sleeve (39).

6. A method for measuring a screw-type magnetoresistive sensor for a main coolant pump, characterized in that: A screw-type magnetoresistive sensor as described in any one of claims 1 to 5 is used, and the screw-type magnetoresistive sensor is radially installed on the main cooling pump main shaft (1) of the rotating machinery. The installation direction of the screw-type magnetoresistive sensor is perpendicular to the main axis of the main cooling pump main shaft (1), and the main cooling pump main shaft (1) is provided with a signal transmitting tooth (2) in the vertical direction along the main axis.

7. The method for measuring a screw-type magnetoresistive sensor for a main coolant pump according to claim 6, characterized in that: A signal enhancement block (4) is provided at the end of the signal transmitting tooth (2).

8. The method for measuring a screw-type magnetoresistive sensor for a main coolant pump according to claim 7, characterized in that: The signal enhancement block (4) is a 20 mm measuring block.

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