Skip bucket hook detection device

Abstract

The utility model relates to a skip bucket hook detection device which comprises a magnetic switch, a magnet, at least one pair of iron wire brushes, at least one pair of iron brush plates, a tension detection assembly sensor, a relay, an alarm and a PCL control facility. The magnet is arranged on the lower side of the hook elbow, the magnetic switch is arranged on the bottom plate, and the maximum conduction distance of the magnetic switch is the distance between the magnet and the magnetic switch when the roller is separated from the straight rail; iron brush plates are arranged on the side parts of the skip buckets; iron wire brushes are arranged beside the skip buckets at the lower ends of the straight rails; the tension detection assembly is arranged between the hook and the bottom plate and comprises a contact probe, and the contact probe detects whether acting force of the cross bar on the hook exists on the hook or not; the magnetic switch, the contact probe, the iron wire brush, the iron brush plate and the relay are located in the same loop, the relay is connected with the input end of the PLC control facility, the skip bucket hanging detection device is reliable in detection structure, the situation that a skip bucket is not hung can be accurately judged, a correct response is made, and accidents are avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of hoists, and particularly relates to a skip hook detection device. Background Art

[0002] A skip is a container directly used for loading useful minerals, waste rocks, coal or gangue in a mine. In mine exploitation, two main shaft skips are repeatedly lifted up and down to realize underground loading and surface unloading of minerals. After the skip unloads at the unloading station at the top of the shaft and turns to move downward, the roller moves in a straight track. When the roller descends and disengages from the straight track, the skip hook catches on a round steel, which is a cross bar welded to the lower part of the frame. If the hook does not catch firmly, it will cause the skip bin door not to close, resulting in problems of equipment and facility losses, greatly improving the equipment working efficiency and safe operation.

[0003] The Chinese utility model patent application No. 201911297126.9, with a publication date of February 28, 2020, discloses a skip box hook monitoring device for monitoring whether the hook is hooked in place. It includes a flat steel arranged at the hook head position cooperating with a limit switch arranged beside a groove, and an elastic contact arranged on the shaft wall cooperating with a metal plate on the skip box. When both are connected to the circuit, it is judged that the hook is hooked in place. In this scheme, the limit switch uses a rocker type micro switch, which emits a signal through the physical contact between the flat steel and the rocker. In the construction of mine loading, the internal environment of the hoist is very bad. Mine slag and coal blocks often get stuck in the corners and gaps of the equipment, and wet coal slag adheres to a large number of internal components of the hoist. A large amount of coal gangue slag and powder is easily adhered to the flat steel, forming foreign matter accumulation. When the hook actually does not enter the groove, the extrusion of the foreign matter on the rocker generates a wrong signal, and even causes extrusion damage to the rocker; the flat steel has a large volume and is arranged at the top of the hook, and is easily impacted and deformed by external objects, resulting in inability to contact the rocker at a fixed position.

[0004] If a skip fails due to the hook not being firmly attached, it will increase the labor intensity of workers, invisibly increasing the labor cost. Each time the skip runs, personnel need to check it, which brings great difficulties to both the skip operation and the personnel. Content of the Utility Model

[0005] The technical problem to be solved by the utility model is that the existing skip hook monitoring device is easily damaged and loses the monitoring function under harsh working conditions, and the components are easily deformed and the detection signal is inaccurate.

[0006] The technical solution adopted by the utility model to solve the above problems is as follows:

[0007] A skip hook detection device includes a relay, an alarm, and a PLC control facility. It also includes a detection component installed on the skip. The skip includes a steel frame formed by integrally fixing a side wing plate and a bottom plate. A hopper box is provided at the upper part of the steel frame, a box door is provided at the lower side of the hopper box, skip rollers are provided at the lower part of the steel frame, the rollers are slidably connected to a straight rail located in the unloading station, a hook is provided on the back side of the rollers. The hook is composed of an upper swing arm, a lower swing arm, and a connecting shaft. Both ends of the connecting shaft are connected to the side wing plate of the steel frame through bearing seats. The upper end of the lower swing arm is fixedly connected to the connecting shaft, and the roller is installed at the lower end. The lower end of the upper swing arm is fixedly connected to the connecting shaft, and an elbow is provided at the upper end. A support is fixedly connected to the bottom plate, a cross bar is fixedly connected to the top of the support. A first spring is installed on one side of the upper swing arm close to the connecting shaft, and the lower end of the first spring is connected to the bottom plate. The detection component includes a magnetic switch and a magnet. The magnet is provided below the elbow of the hook, and the magnetic switch is provided on the bottom plate below the magnet. The maximum conduction distance of the magnetic switch is the distance between the magnet and the magnetic switch when the roller is separated from the straight rail. The detection component also includes an iron brush plate and a wire brush. An insulating plate is provided on the side of the skip, the iron brush plate is provided outside the insulating plate, and the wire brush is provided beside the skip at the elevation height of the lower end of the straight rail. The detection component also includes a tensile force detection component, which is provided between the hook and the bottom plate. The tensile force detection component includes a contact probe, and the contact probe detects whether there is a force on the hook from the cross bar. The magnetic switch, the contact probe, the wire brush, the iron brush plate, and the relay are in the same circuit. The relay is connected to the input end of the PLC control facility, and the output end of the PLC control facility is connected to the alarm and the hoist motor.

[0008] The beneficial effects of the present invention with the above structure compared with the prior art are as follows:

[0009] This solution is used for the bottom-dumping skip of the hoist, and the skip detection is involved in the automatic control, improving the intelligent control means. 1) The present invention uses a magnetic switch to detect the height action change of the elbow, and judges the height when the hook hangs down to grasp the cross bar. The magnetic switch is not easily damaged, and the attached dirt does not affect the signal generation, making the judgment signal of the detection device more accurate. 2) The present invention uses a tensile force detection component to detect the horizontal position of the hook. When the contact probe detects that the hook is resisted by the cross bar when it hangs down, it cooperates with the magnetic switch to judge the situation of the hook grasping the cross bar from two dimensions of vertical and horizontal, and can more accurately judge the authenticity and firmness of the hook grasping, can accurately judge the situation that the skip is not hung and make a correct response, avoiding the occurrence of accidents.

[0010] As a preference, a further technical solution of the above structure is as follows:

[0011] Optionally, a maintenance platform is provided beside the unloading station of the hoist. The iron brush plate is provided at one side edge of the bottom plate close to the maintenance platform. The iron brush plate includes a conductive plate with an arc-shaped outer surface. Fixed ears are fixed on both sides of the conductive plate, and the two fixed ears are fixed to the bottom plate through bolts.

[0012] The iron wire brush is a cylindrical brush with 360-degree bristles. Its two ends are fixedly connected to the bracket, and the bracket is fixedly installed on the maintenance platform.

[0013] The magnet is installed on the hook through the fixing seat. The upper side of the fixing seat is welded and fixed to the hook, and a groove is provided on the lower side. The magnet is a round button-shaped magnetic block, and the magnet is embedded in the groove.

[0014] The tensile force detection component includes a housing, a core column, a second spring, and a contact probe. The housing includes a sleeve. The upper end of the sleeve is fixedly connected with an upper connecting ear, and the lower end of the sleeve is coaxially fixedly connected with a sliding sleeve. The inner wall of the central hole of the sliding sleeve is fixedly embedded with the contact probe. The core column has a diameter matching the central hole of the sliding sleeve and its upper end penetrates through the sliding sleeve. The upper end of the core column is fixedly connected with a baffle, and the lower end is fixedly connected with a lower connecting ear. Measuring points are embedded on the outer wall of the core column. The second spring is sleeved on the core column, with the upper end abutting against the baffle and the lower end abutting against the top surface of the sliding sleeve. The contact probe contacts the measuring points to conduct the circuit. Description of the Drawings

[0015] Figure 1 is a schematic diagram of the overall structure of the present utility model;

[0016] Figure 2 is a schematic diagram of the circuit layout of the detection device of the present utility model;

[0017] Figure 3 is a schematic diagram of the hook linkage component of the present utility model;

[0018] Figure 4 is a perspective view of the structure of the tensile force detection component of the present utility model;

[0019] Figure 5 is an exploded view of the tensile force detection component of the present utility model;

[0020] Figure 6 is a schematic diagram of the magnet installation structure of the present utility model;

[0021] Figure 7 is a schematic diagram of the magnetic switch installation structure of the present utility model;

[0022] Figure 8 is a schematic diagram of the iron brush plate installation structure of the present utility model;

[0023] Figure 9 is a schematic diagram of the wire brush installation structure of the present utility model.

[0024] In the figure: 1, hopper box; 2, side wing plate; 3, bottom plate; 4, support; 5, cross bar; 6, roller; 7, hook; 701, lower swing arm; 702, connecting shaft; 703, upper swing arm; 704, elbow; 8, straight rail; 9, wire brush; 901, support; 902, maintenance platform; 10, iron brush plate; 101, fixed ear; 11, magnet; 1101, fixed seat; 12, magnetic switch; 1201, mounting seat; 13, insulating plate; 14, relay; 15, PLC control facility; 16, alarm; 17, hoist motor; 18, contact probe; 1801, measuring point; 19, first spring; 20, tensile force detection component; 2001, upper connecting ear; 2002, sleeve; 2003, second spring; 2004, sliding sleeve; 2005, core column; 2006, baffle; 2007, lower connecting ear. Detailed implementation mode

[0025] The following further illustrates the present utility model in conjunction with embodiments. The purpose is only to better understand the content of the present utility model. Therefore, the examples given do not limit the protection scope of the present utility model.

[0026] See Figure 1 , the present utility model relates to a detection device for a skip hook 7, including a corresponding magnetic switch 12 and magnet 11, at least a pair of wire brushes 9 and iron brush plates 10 arranged correspondingly, a tensile force detection component 20 sensor, as well as a relay 14, an alarm 16 and a PCL control facility, etc.

[0027] This skip hook 7 detection device is applied to the bottom-dumping skip of a hoist and is installed at the ground unloading station, connecting the skip detection to the automatic control to improve the intelligent control means of the equipment.

[0028] The skip includes a steel frame fixedly connected by a side wing plate 2 and a bottom plate 3. A hopper box 1 is arranged on the upper part of the steel frame. A box door is arranged on the lower side of the hopper box 1. Skip rollers 6 are arranged on the lower part of the steel frame. The rollers 6 are slidably connected with a straight rail 8 located in the unloading station. A hook 7 is arranged on the back side of the roller 6. The hook is composed of an upper swing arm 703, a lower swing arm 701 and a connecting shaft 702. Both ends of the connecting shaft 702 are connected to the side wing plate 2 of the steel frame through bearing seats. The upper end of the lower swing arm 701 is fixedly connected to the connecting shaft 702, and the lower end installs the roller 6. The lower end of the upper swing arm 703 is fixedly connected to the connecting shaft 702, and the upper end is provided with an elbow 704. A support 4 is fixedly connected to the bottom plate 3, and a cross bar 5 is fixedly connected to the top of the support 4. A first spring 19 is installed on the side of the upper swing arm 703 close to the connecting shaft 702. The lower end of the first spring 19 is connected to the bottom plate 3.

[0029] The magnet 11 is arranged on the lower side of the elbow 704 of the hook 7, and the magnetic switch 12 is arranged on the bottom plate 3 below the magnet 11. The maximum conduction distance of the magnetic switch 12 is the distance between the magnet 11 and the magnetic switch 12 when the roller 6 is separated from the straight rail 8.

[0030] An insulating plate 13 is provided on the side of the skip. An iron brush plate 10 is arranged outside the insulating plate 13, and a wire brush 9 is arranged beside the skip at the elevation height of the lower end of the straight rail 8.

[0031] The tension detection assembly 20 is arranged between the hook 7 and the bottom plate 3. The tension detection assembly 20 includes a contact probe 18, and the contact probe 18 detects whether there is a force exerted on the hook 7 by the cross bar 5 on the hook 7.

[0032] The magnetic switch 12, the contact probe 18, the wire brush 9, the iron brush plate 10 and the relay 14 are in the same circuit. The relay 14 is connected to the input end of the PLC control facility 15, and the output end of the PLC control facility 15 is connected to the alarm 16 and the hoist motor 17.

[0033] See Figure 2 , in the utility model, the magnetic switch 12 and the iron brush plate 10 are arranged on the skip, and the wire brush 9 is arranged on the wellbore side to contact the iron brush plate 10 to close the circuit. The power supply of the utility model adopts a 24V engineering power supply to replace the commonly used 24V output storage battery; in the utility model, the installation position of the relay 14 is moved from the skip to the management station, and the way of controlling the single-side coil of the relay 14 is adopted, which is more convenient for daily maintenance and inspection. After the magnetic switch 12 acts, the normally open point of the relay 14 is disconnected and the normally closed point is closed, and the electrical signal is transmitted to the signal system PLC control facility 15. The PLC detects whether the grab hook is firmly grasped according to the set logical relationship, controls the connection point of the hoisting signal system through the program logic, and changes from the moving point to the stop point to stop the vehicle.

[0034] See Figure 3 , Figure 4 and Figure 5 , the tension detection assembly 20 includes a housing, a core column 2005, a second spring 2003 and a contact probe 18. The housing includes a sleeve 2002. The upper end of the sleeve 2002 is fixedly connected with an upper connecting ear 2001, and the lower end of the sleeve 2002 is coaxially and fixedly connected with a sliding sleeve 2004. The inner wall of the central hole of the sliding sleeve 2004 is fixedly embedded with the contact probe 18; the core column 2005, the diameter of which matches the central hole of the sliding sleeve 2004 and the upper end of which penetrates through the sliding sleeve 2004. The upper end of the core column 2005 is fixedly connected with a baffle 2006, and the lower end is fixedly connected with a lower connecting ear 2007. A measuring point 1801 is embedded on the outer wall of the core column 2005; the second spring 2003 is sleeved on the core column 2005, the upper end of which abuts against the baffle 2006, and the lower end abuts against the top surface of the sliding sleeve 2004; the contact probe 18 contacts the measuring point 1801 to conduct the circuit.

[0035] Principle of the setting of the pulling force detection component 20 of the present utility model: When the skip is at the unloading station, the roller 6 at the lower end of the hook 7 is in the straight rail 8. The straight rail 8 exerts a downward pressure on the hook 7, so that the elbow 704 end of the hook 7 is in an upward rotation state at this time, the elevation angle of the hook 7 is large, and the first spring 19 is subjected to a large pulling force; when the skip runs downward from the unloading station, when the roller 6 leaves the straight rail 8, the hook 7 is released, and the first spring 19 immediately recovers the pulling force, causing the elbow 704 to rotate downward. If the elbow 704 can catch on the cross bar 5, the recovery of the pulling force of the first spring 19 stops; if the equipment is abnormal and the horizontal position of the hook 7 is behind, the elbow 704 cannot catch the cross bar 5, and the first spring 19 will completely recover the pulling force.

[0036] The contact probe 18 is in contact with the measuring point 1801 and closes. The measuring point 1801 is designed to have a certain width to avoid point position deviation caused by a small amount of foreign matter on the elbow 704 or the cross bar 5 that does not affect catching, and to avoid point position deviation caused by deformation efficiency differences caused by spring loss. When the hook 7 rotates upward, the hook 7 pulls the outer shell upward, the second spring 2003 is compressed, and the measuring point 1801 is located below the contact probe 18; when the hook 7 rotates downward but does not catch on the cross bar 5, the tension of the second spring 2003 causes the core column 2005 to shrink inward, and the measuring point 1801 is pushed to the upper side of the contact probe 18; only when the elbow 704 of the hook 7 catches the cross bar 5, the contact probe 18 is in contact with the measuring point 1801.

[0037] The second spring 2003 of the present utility model also plays a role in pulling the hook 7 downward. Therefore, the embodiment of the pulling force detection component 20 not only has the function of detecting the position of the elbow 704, but also has the function of assisting the first spring 19 to increase the grasping force of the elbow 704 on the cross bar 5.

[0038] Since the skip is always in operation during the ore loading and unloading process, and considering the presence of water spray in the on-site environment, insulating materials are installed at the wiring points of the explosion-proof magnetic switch 12 and the wire brush 9 installed on the skip to isolate them, and 24V safety voltage is used as the control power supply to ensure the safety of electricity use and the conductivity of the control circuit.

[0039] The present utility model consists of an explosion-proof magnetic switch 12 and a magnet 11 to form a hook detection facility. The magnetic switch 12 serves as a fixed detection point 1801, and the magnet 11 moves integrally with the hook to detect the up and down movement of the hook 7. The magnetic switch 12 is not easily damaged, and the attached dirt does not affect the signal generation.

[0040] Installation embodiment of the magnet 11: Refer to Figure 6 , the magnet 11 is installed on the hook 7 through a fixing seat 1101. The upper side of the fixing seat 1101 is welded and fixed to the hook 7, and a groove is provided on the lower side. The magnet 11 is a round button-shaped magnetic block, and the magnet 11 is embedded in the groove.

[0041] Installation embodiment of the magnetic switch 12, see Figure 7 , the magnetic switch 12 is installed on the bottom plate 3 through the mounting seat 1201. The mounting seat 1201 is a short angle steel, which is vertically welded to the bottom plate 3. Bolt holes are provided on one side plate surface. The magnetic probe of the magnetic switch 12 is set upward and fixed to the short angle steel through bolts.

[0042] Installation embodiment of the iron brush plate 10, see Figure 8 , there is a maintenance platform 902 beside the discharge station of the hoist. The iron brush plate 10 is arranged on one side edge of the bottom plate 3 close to the maintenance platform 902. The iron brush plate 10 includes a conductive plate with an arc-shaped outer surface. Fixed ears 101 are fixed on both sides of the conductive plate, and the two fixed ears 101 are fixed to the bottom plate 3 through bolts.

[0043] Installation embodiment of the wire brush 9, see Figure 9 , the wire brush 9 is a cylindrical brush with 360-degree bristles. Its two ends are fixedly connected to the bracket 901, and the bracket 901 is fixedly installed on the maintenance platform 902.

[0044] Circuit principle of the present utility model:

[0045] 1) Magnetic switch 12: When the hook 7 rotates downward, the magnet 11 approaches the magnetic switch 12. The magnetic contact of the magnetic switch 12 and the magnet 11 makes the contact closed, and the circuit is conducted; 2) Contact probe 18: When the hook 7 rotates downward, the second spring 2003 releases force, pushing the contact probe 18 to move downward. When the hook 7 catches on the crossbar 5, the force release of the spring stops, and the contact probe 18 contacts the measuring point 1801 to close the circuit; 3) Wire brush 9 and iron brush plate 10: When the skip descends to make the iron brush plate 10 contact the wire brush 9, the circuit is closed; When all the above three points are met, the relay 14 is electrically conducted, and the auxiliary contact of the relay 14 is closed, sending a signal to the PCL control facility. The PLC receives the detection signal for the internal logic program and processes it. At this time, the buzzer indicator light on the unloading station operation console lights up and beeps. After the detection is correct, the hoist continues to run. If any one of the three conditions is not met, the 24V relay 14 does not act, the PLC digital input module channel does not receive the switch quantity signal, the PLC does not detect the switch quantity signal, the PLC internal logic program delays to disconnect the signal contact point, and changes the signal moving skip point to the stop skip point. At this time, the buzzer indicator light on the unloading station operation console will not light up and will not beep, the signal system and the electric control system interlock point are disconnected, and the hoist stops running.

[0046] The utility model has the following advantages: The magnetic switch 12 and the magnet 11 are in magnetic contact and closed. The magnetic switch 12 is not easily deprived of signals due to physical contamination or blockage. Both the magnetic switch 12 and the magnet 11 are located on the back of the falling object and are not easily damaged, making the signals of the detection device more reliable. The contact probe 18 of the utility model is inside the sliding sleeve 2004, avoiding signal loss due to contamination. The structure of the skip enables the hook 7 to move in the same plane. If the vertical and horizontal positions in this plane are both determined at the position of the cross bar 5, it can undoubtedly be determined that the cross bar 5 has been caught. The wire brush 9 of the utility model uses 360-degree bristles. When the side that has long-term collision contact with the iron brush plate 10 is worn out, the angle can be directly rotated so that new bristles are in contact with the iron brush plate 10, and the service life is longer.

[0047] The above are only the preferred and feasible embodiments of the utility model, and do not limit the scope of rights of the utility model. Any equivalent changes made by using the content of the specification and drawings of the utility model are included in the scope of rights of the utility model.

Claims

1. A skip hook detection device, comprising a relay (14), an alarm (16) and a PLC control facility (15), and further comprising a detection component mounted on the skip. The skip includes a steel frame integrally formed by a side wing plate (2) and a bottom plate (3). A skip box (1) is provided at the upper part of the steel frame. A box door is provided at the lower side of the skip box (1). Skip rollers (6) are provided at the lower part of the steel frame. The rollers (6) are slidably connected to a straight rail (8) located in the unloading station. A hook (7) is provided on the back side of the roller (6). The hook (7) is composed of an upper swing arm (703), a lower swing arm (701) and a connecting shaft (702). Both ends of the connecting shaft (702) are connected to the side wing plate (2) of the steel frame through bearing seats. The upper end of the lower swing arm (701) is fixedly connected to the connecting shaft (702), and the lower end is provided with the roller (6). The lower end of the upper swing arm (703) is fixedly connected to the connecting shaft (702), and the upper end is provided with an elbow (704). A support (4) is fixedly connected to the bottom plate (3), and a cross bar (5) is fixedly connected to the top of the support (4). A first spring (19) is installed on one side of the upper swing arm (703) close to the connecting shaft (702). The lower end of the first spring (19) is connected to the bottom plate (3). It is characterized in that: The detection component includes a magnetic switch (12) and a magnet (11). The magnet (11) is provided on the lower side of the elbow (704) of the hook (7). The magnetic switch (12) is provided on the bottom plate (3) below the magnet (11). The maximum conduction distance of the magnetic switch (12) is the distance between the magnet (11) and the magnetic switch (12) when the roller (6) is separated from the straight rail (8). The detection component further includes an iron brush plate (10) and an iron wire brush (9). An insulating plate (13) is provided on the side of the skip. The iron brush plate (10) is provided on the outer side of the insulating plate (13). The iron wire brush (9) is provided beside the skip at the elevation height of the lower end of the straight rail (8). The detection component further includes a tensile force detection component (20). The tensile force detection component (20) is provided between the hook (7) and the bottom plate (3). The tensile force detection component (20) includes a contact probe (18). The contact probe (18) detects whether there is a force exerted on the hook (7) by the cross bar (5) on the hook (7). The magnetic switch (12), the contact probe (18), the iron wire brush (9), the iron brush plate (10) and the relay (14) are in the same circuit. The relay (14) is connected to the input end of the PLC control facility (15). The output end of the PLC control facility (15) is connected to the alarm (16) and the hoist motor (17).

2. The skip hook detection device according to claim 1, characterized in that: There is a maintenance platform (902) beside the hoist unloading station. The iron brush plate (10) is provided at one side edge of the bottom plate (3) close to the maintenance platform (902). The iron brush plate (10) includes a conductive plate with an arc-shaped outer surface. Fixed ears (101) are fixed on both sides of the conductive plate. The two fixed ears (101) are fixed to the bottom plate (3) by bolts.

3. The skip hook detection device according to claim 2, wherein: The iron wire brush (9) is a cylindrical brush with 360-degree bristles. Its two ends are fixedly connected to a bracket (901). The bracket (901) is fixedly installed on the maintenance platform (902).

4. The skip hook detection device according to claim 1, wherein: The magnet (11) is mounted on the hook (7) through the fixing base (1101). The upper side of the fixing base (1101) is fixedly welded to the hook (7), and a groove is provided on the lower side. The magnet (11) is a round button-shaped magnetic block, and the magnet (11) is embedded in the groove.

5. The skip hook detection device according to claim 1, characterized in that: The magnetic switch (12) is mounted on the bottom plate (3) through the mounting base (1201). The mounting base (1201) is a short angle steel, and the short angle steel is vertically welded to the bottom plate (3). Bolt holes are provided on one side plate surface. The magnetic probe of the magnetic switch (12) is arranged upward and is fixed to the short angle steel by bolts.

6. The skip hook detection device according to claim 1, characterized in that: The tensile force detection component (20) includes a housing, a core column (2005), a second spring (2003), and a contact probe (18). The housing includes a sleeve (2002). The upper end of the sleeve (2002) is fixedly connected with an upper connecting ear (2001). The lower end of the sleeve (2002) is coaxially fixedly connected with a sliding sleeve (2004). The contact probe (18) is embedded and fixed on the inner wall of the central hole of the sliding sleeve (2004). The core column (2005) has a diameter matching the central hole of the sliding sleeve (2004), and its upper end penetrates through the sliding sleeve (2004). The upper end of the core column (2005) is fixedly connected with a baffle plate (2006), and the lower end is fixedly connected with a lower connecting ear (2007). Measuring points (1801) are embedded on the outer wall of the core column (2005). The second spring (2003) is sleeved on the core column (2005), with its upper end abutting against the baffle plate (2006) and its lower end abutting against the top surface of the sliding sleeve (2004). The contact probe (18) contacts the measuring point (1801) to conduct the circuit.

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