Hydraulic fluid wear resistance testing unit

Abstract

The invention discloses a hydraulic fluid anti-wear performance test unit, and relates to the technical field of hydraulic fluid performance testing, the hydraulic fluid anti-wear performance test unit comprises a shell, a stator, a rotor, a large blade, a small blade, an upper oil distribution disc and a lower oil distribution disc, the shell is internally provided with a hollow cavity, and the upper oil distribution disc, the stator and the lower oil distribution disc form a pump body; the rotor is rotatably connected in the pump body around a first rotating shaft, an oil cavity in the pump body forms an oil pumping area, and an oil cavity outside the pump body forms an oil outlet area; a first type of groove and a second type of groove are formed in the rotor, the large blades are arranged in the first type of groove and can slide in the radial direction of the rotor along with rotation of the rotor, the small blades are detachably connected in the second type of groove, and the bottoms of the small blades make contact with the lower oil distribution disc. The hydraulic fluid anti-wear performance test unit can truly simulate the working state of a vane pump and the working environment of vanes, and the hydraulic fluid performance can be well evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic fluid performance testing, in particular to a hydraulic fluid anti-wear performance testing unit. Background Art

[0002] The vane pump is an important hydraulic power component with a complex internal structure and multiple pairs of friction pairs working simultaneously during operation. Hydraulic fluid can lubricate the friction pairs and extend the service life of the vane pump. However, if the hydraulic fluid has weak anti-wear performance, the blades will be severely worn, the movement law of the blades will change, and then cause vibration and noise of the pump, and affect the volumetric efficiency of the pump, and finally lead to pump failure. Therefore, it is very important to test the anti-wear performance of the hydraulic fluid. Traditional standard friction testers such as four-ball friction testers, SRV friction and wear testers and other general testing equipment cannot simulate the actual environment inside the vane pump, and their test results are poorly correlated with the vane pump. Therefore, there is an urgent need for a hydraulic fluid anti-wear performance test unit that has a stronger correlation with the vane pump, can truly simulate the working state of the vane pump and the working environment of the blades, and can well evaluate the performance of the hydraulic fluid. Summary of the invention

[0003] The purpose of the present invention is to provide a hydraulic fluid anti-wear performance test unit to solve the problems existing in the above-mentioned prior art, which has a stronger relevance to the vane pump, can truly simulate the working state of the vane pump and the working environment of the blades, and well evaluate the performance of the hydraulic fluid.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a hydraulic fluid anti-wear performance test unit, comprising: a housing, a stator, a rotor, a large blade, a small blade, an upper oil distribution plate and a lower oil distribution plate, wherein the housing has a hollow cavity, the lower oil distribution plate is fixedly connected to the bottom of the cavity, the stator is annular, the stator is fixedly connected to the upper end of the lower oil distribution plate, the upper oil distribution plate is fixedly connected to the upper end of the stator, the upper oil distribution plate, the stator and the lower oil distribution plate form a pump body, the rotor is rotatably connected to the pump body around a first rotating shaft, the first rotating shaft coincides with the central axis of the rotor, there is a distance between the central axis of the rotor and the central axis of the stator, and the lower oil distribution plate divides the cavity into an oil suction area and an oil cavity, The oil cavity in the pump body forms an oil pumping area, and the oil cavity outside the pump body forms an oil outlet area. The lower oil distribution plate is provided with an oil inlet groove connecting the oil suction area and the oil pumping area; the upper oil distribution plate is provided with an oil outlet groove connecting the oil pumping area and the oil outlet area. The outer shell is provided with an oil inlet connecting the oil inlet area with the outside world and an oil outlet connecting the oil outlet with the outside world. The rotor is used to connect an external power source; the rotor is provided with a first type of groove and a second type of groove, the large blade is provided in the first type of groove and can slide along the radial direction of the rotor as the rotor rotates, the small blade is detachably connected in the second type of groove, and the bottom of the small blade is in contact with the lower oil distribution plate.

[0006] In some embodiments, a fixing bolt is also included, and a fixing screw hole connecting the second type of groove with the outside is provided on the side of the rotor. The fixing bolt is screwed into the fixing screw hole and rests against the side of the small blade; the assembly method between the large blade and the first type of groove is clearance fit.

[0007] In some embodiments, an axial fixing member is further included, which is fixedly installed in the second type of groove and located at the top of the small blade. The assembly method between the small blade and the second type of groove is interference fit, and the bottom of the axial fixing member is in contact with the top of the small blade.

[0008] In some embodiments, the first type grooves and the second type grooves are evenly spaced along the circumference of the rotor and the number of the first type grooves and the second type grooves is equal, each of the first type grooves is provided with the large blade, and each of the second type grooves is provided with the small blade.

[0009] In some embodiments, a tenon bolt is further included, which passes through the upper oil distribution plate, the stator and the lower oil distribution plate and fixes the upper oil distribution plate, the stator and the lower oil distribution plate together.

[0010] In some embodiments, the shell includes an upper cover and a bottom support, the lower end of the upper cover is detachably connected to the upper end of the bottom support, the oil inlet is arranged on the bottom support, the oil outlet is arranged on the upper cover, and the lower end of the bottom support is used to be connected to a hydraulic lifting platform.

[0011] In some embodiments, a drive shaft is also included, and mounting holes are provided on the upper cover and the upper oil distribution plate. One end of the drive shaft passes through two mounting holes and is detachably fixed to the rotor through a driving positioning pin. The drive shaft is coaxially arranged with the rotor, and the drive shaft is used to connect to a power device.

[0012] In some embodiments, a mounting groove is provided on the upper side of the base, the lower oil distribution plate is detachably fixedly connected in the mounting groove, the side wall of the lower oil distribution plate is fitted with the side wall of the mounting groove, there is a gap between the bottom of the lower oil distribution plate and the inner bottom surface of the mounting groove, and the oil absorption area is formed between the lower oil distribution plate and the inner bottom surface of the mounting groove.

[0013] In some embodiments, a lower positioning pin is further included, a vertical first socket is provided on the lower oil distribution plate, an axis of the first socket is spaced apart from a center axis of the lower oil distribution plate, a second socket connected to the first socket is provided on the base support, and the lower positioning pin is inserted into the first socket and the second socket.

[0014] In some embodiments, a connecting bolt is further included, the base bracket is provided with a connecting through hole connecting the two sides of the base bracket, the lower end surface of the upper cover is provided with a mounting screw hole corresponding to the position of the connecting through hole, the connecting bolt passes through the connecting through hole and is threadedly connected in the mounting screw hole.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The hydraulic fluid anti-wear performance test unit provided by the present invention has a rotor that rotates eccentrically relative to a stator during operation, and a large blade moves radially along the mover as the rotor rotates, thereby pumping hydraulic fluid. The hydraulic fluid enters the oil suction area from the oil inlet, passes through the oil inlet groove and is sucked into the oil pumping area, then passes through the oil outlet groove and enters the oil outlet area, and is finally discharged from the oil outlet. The hydraulic fluid circulates in the test unit, truly simulating the working state of the vane pump and the working environment of the blades. At the same time, during the rotation of the rotor, the end face of the large blade forms a friction pair with the inner wall of the stator, simulating the friction between the blade and the inner wall of the stator in the vane pump. After weighing the weight of the large blade before and after work, the staff can simultaneously evaluate the lubrication of the hydraulic fluid between the blade and the inner wall of the stator and between the blade and the lower oil distribution plate in the vane pump; the small blade is fixedly connected in the second type of groove, and the bottom of the small blade forms a friction pair with the lower oil distribution plate, simulating the friction between the blade and the lower oil distribution plate in the vane pump. After weighing the weight of the second blade before and after work, the staff can evaluate the lubrication of the hydraulic fluid between the blade and the lower oil distribution plate in the vane pump. Therefore, the hydraulic fluid anti-wear performance test unit in the present invention can truly simulate the working state of the vane pump and the working environment of the blade, and well evaluate the wear of the blade in the vane pump, and then well evaluate the anti-wear performance of the hydraulic fluid, so as to quickly and effectively pre-screen and sort the hydraulic fluid in the oil product development stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 paying creative work.

[0018] Figure 1 It is a three-dimensional structural diagram of a hydraulic fluid anti-wear performance testing unit in some embodiments of the present invention;

[0019] Figure 2 for Figure 1 Exploded view of the hydraulic fluid anti-wear performance test unit;

[0020] Figure 3 for Figure 1 A cross-sectional view of a hydraulic fluid anti-wear performance test unit;

[0021] Figure 4 A three-dimensional structural diagram of a rotor and a lower oil distribution plate in some embodiments of the present invention;

[0022] Figure 5 for Figure 4 A cross-sectional view of the middle mover along a horizontal plane;

[0023] Figure 6 for Figure 4 a cross-sectional view of the middle mover along another horizontal plane;

[0024] In the figure: 1. upper cover; 2. bottom support; 3. stator; 4. rotor; 5. large blades; 6. small blades; 7. lower oil distribution plate; 8. upper oil distribution plate; 9. drive shaft; 10. oil chamber; 11. oil suction area; 12. oil outlet area; 13. oil pumping area; 14. oil inlet; 15. oil outlet; 16. oil inlet groove; 17. oil outlet groove; 18. first type groove; 19. second type groove; 20. bolt with tenon; 21. axial fixing piece; 22. lower positioning pin; 23. connecting bolt; 24. driving positioning pin; 25. fixing bolt. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The purpose of the present invention is to provide a hydraulic fluid anti-wear performance test unit to solve the problems existing in the above-mentioned prior art, which has a stronger relevance to the vane pump, can truly simulate the working state of the vane pump and the working environment of the blades, and well evaluate the performance of the hydraulic fluid.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention provides a hydraulic fluid anti-wear performance testing unit, such as Figure 1-6As shown, it includes: a housing, a stator 3, a rotor 4, a large blade 5, a small blade 6, an upper oil distribution plate 8 and a lower oil distribution plate 7. The housing has a hollow cavity. The lower oil distribution plate 7 is fixedly connected to the bottom of the cavity. The stator 3 is annular. The stator 3 is fixedly connected to the upper end of the lower oil distribution plate 7. The upper oil distribution plate 8 is fixedly connected to the upper end of the stator 3. The upper oil distribution plate 8, the stator 3 and the lower oil distribution plate 7 form a pump body. The rotor 4 rotates around a first rotating shaft and is connected to the pump body. The first rotating shaft coincides with the central axis of the rotor 4. There is a distance between the central axis of the rotor 4 and the central axis of the stator 3. The lower oil distribution plate 7 divides the cavity into an oil suction area 11 and an oil cavity 10. The oil cavity 10 in the pump body forms an oil pumping area 13. The oil cavity 10 outside the pump body forms an oil outlet area 12, and the lower oil distribution plate 7 is provided with an oil inlet groove 16 connecting the oil suction area 11 and the oil pumping area 13; the upper oil distribution plate 8 is provided with an oil outlet groove 17 connecting the oil pumping area 13 and the oil outlet area 12, and the outer shell is provided with an oil inlet 14 connecting the oil inlet area with the outside world and an oil outlet 15 connecting the oil outlet with the outside world. The rotor 4 is used to connect an external power source; the rotor 4 is provided with a first type of groove 18 and a second type of groove 19, the large blade 5 is arranged in the first type of groove 18 and can slide along the radial direction of the rotor 4 as the rotor 4 rotates, and the small blade 6 is detachably connected in the second type of groove 19, and the bottom of the small blade 6 is in contact with the lower oil distribution plate 7.

[0029] In the hydraulic fluid anti-wear performance test unit provided by the present invention, large blades 5 and small blades 6 of equal number are spaced apart on the rotor 4. During operation, the rotor 4 rotates eccentrically relative to the stator 3, and the large blades 5 move along the radial direction of the mover with the rotation of the rotor 4, thereby pumping the hydraulic fluid, and the hydraulic fluid enters the oil suction area 11 from the oil inlet 14, passes through the oil inlet groove 16 and is sucked into the oil pumping area 13, then passes through the oil outlet groove 17 and enters the oil outlet area 12, and is finally discharged from the oil outlet 15. The hydraulic fluid circulates in the test unit, truly simulating the working state of the vane pump and the working environment of the vane. At the same time, during the rotation of the rotor 4, the end face of the large blade 5 forms a friction pair with the inner side wall of the stator 3, simulating the friction between the blade and the inner side wall of the stator 3 in the vane pump. After weighing the weight of the large blade 5 before and after work, the staff can simultaneously evaluate the lubrication of the hydraulic fluid between the blade and the inner side wall of the stator 3 and between the blade and the lower oil distribution plate 7 in the vane pump; the small blade 6 is fixedly connected in the second type of groove 19, and the bottom of the small blade 6 forms a friction pair with the lower oil distribution plate 7, simulating the friction between the blade and the lower oil distribution plate 7 in the vane pump. After weighing the weight of the second blade before and after work, the staff can evaluate the lubrication of the hydraulic fluid between the blade and the lower oil distribution plate 7 in the vane pump. Therefore, the hydraulic fluid anti-wear performance test unit in the present invention can truly simulate the working state of the vane pump and the working environment of the blade, and well evaluate the wear of the blade in the vane pump, and then well evaluate the anti-wear performance of the hydraulic fluid, so as to quickly and effectively pre-screen and sort the hydraulic fluid in the oil product development stage.

[0030] In one implementation of this embodiment, the hydraulic fluid anti-wear performance test unit provided by the present invention further includes a fixing bolt 25. A fixing screw hole connecting the second type groove 19 and the outside is provided on the side of the rotor 4. The fixing bolt 25 is screwed into the fixing screw hole and abuts against the side of the small blade 6. The fixing bolt 25 can prevent the small blade 6 from sliding radially due to the centrifugal force of the rotation of the rotor 4, and ensure that the small blade 6 remains stationary during the rotation of the rotor 4; the large blade 5 and the first type groove 18 are assembled in a clearance fit, and the large blade 5 can slide in the first type groove 18.

[0031] In one embodiment of the present invention, the hydraulic fluid anti-wear performance test unit provided by the present invention further includes an axial fixing member 21, which is fixedly installed in the second type groove 19 and is located at the top of the small blade 6. The assembly method between the small blade 6 and the second type groove 19 is an interference fit, and the bottom of the axial fixing member 21 contacts the top of the small blade 6. The axial fixing member 21 can limit the small blade 6 from the axial direction of the rotor 4, so that the bottom surface of the small blade 6 fits with the upper surface of the lower oil distribution plate 7. Among them, the axial fixing member 21 is preferably spherical, and the axial fixing member 21 and the second type groove 19 are transitionally matched. As long as the position along the axial and radial directions of the rotor 4 is determined, the second blade can be limited without changing the axial fixing angle, which is more convenient to install. At the same time, the fit between the end face of the small blade 6 and the upper end face of the lower oil distribution plate 7 when under pressure can be guaranteed to the greatest extent.

[0032] In one implementation of this embodiment, the first type grooves 18 and the second type grooves 19 are evenly arranged along the circumferential interval of the rotor 4 and the number of the first type grooves 18 and the second type grooves 19 are equal. A large blade 5 is provided in each first type groove 18, and a small blade 6 is provided in each second type groove 19.

[0033] In one implementation of this embodiment, the hydraulic fluid anti-wear performance test unit provided by the present invention further includes a tenon bolt 20, which passes through the upper oil distribution plate 8, the stator 3 and the lower oil distribution plate 7 and fixes the upper oil distribution plate 8, the stator 3 and the lower oil distribution plate 7 together. The tenon bolt 20 can firmly fix the upper oil distribution plate 8, the stator 3 and the lower oil distribution plate 7 together, thereby improving the reliability of the connection.

[0034] In one embodiment of the present invention, the housing includes an upper cover 1 and a bottom bracket 2. The lower end of the upper cover 1 is detachably connected to the upper end of the bottom bracket 2. The oil inlet 14 is arranged on the bottom bracket 2, and the oil outlet 15 is arranged on the upper cover 1. The lower end of the bottom bracket 2 is used to be connected to the hydraulic lifting platform. During the test, the upper end of the upper cover 1 can be limited in the vertical direction, and the bottom bracket 2 can be forced from the vertical direction by the hydraulic test bench, so that the entire hydraulic fluid anti-wear performance test unit can be operated under a harsh environment under pressure, simulating the working environment of the vane pump under harsh working conditions. The test results can provide technical support for the research and development and application of high-performance hydraulic fluid under harsh working conditions. Moreover, by pressurizing the bottom bracket 2, the friction between the small blades 6 and the lower oil distribution plate 7 can be increased, and the wear rate of the small blades 6 can be accelerated, thereby increasing the test speed and shortening the test cycle.

[0035] In one embodiment of the present invention, the hydraulic fluid anti-wear performance test unit provided by the present invention further includes a drive shaft 9. The upper cover 1 and the upper oil distribution plate 8 are both provided with mounting through holes. One end of the drive shaft 9 passes through the two mounting through holes and is detachably fixedly connected to the rotor 4 through the driving positioning pin 24. The drive shaft 9 is coaxially arranged with the rotor 4 and is used to connect to the power equipment. The drive shaft 9 can be connected to the power source and transmit torque to the rotor 4, so that the rotor 4 rotates.

[0036] In one embodiment of the present embodiment, a mounting groove is provided on the upper side of the base 2, and the lower oil distribution plate 7 is detachably fixedly connected in the mounting groove, the side wall of the lower oil distribution plate 7 is fitted with the side wall of the mounting groove, and there is a gap between the bottom of the lower oil distribution plate 7 and the inner bottom surface of the mounting groove, and an oil suction area 11 is formed between the lower oil distribution plate 7 and the inner bottom surface of the mounting groove. When the mover rotates, the hydraulic fluid enters from the oil inlet 14, then enters the oil suction area 11, and then enters the pump through the oil inlet groove 16, and is pumped out through the oil outlet groove 17 under the pumping of the large blade 5, and finally flows out from the oil outlet 15.

[0037] In one embodiment of the present invention, the hydraulic fluid anti-wear performance test unit provided by the present invention further includes a lower positioning pin 22, a vertical first plug hole is provided on the lower oil distribution plate 7, the axis of the first plug hole is spaced from the central axis of the lower oil distribution plate 7, a second plug hole connected to the first plug hole is provided on the bottom bracket 2, and the lower positioning pin 22 is inserted into the first plug hole and the second plug hole. The lower positioning pin 22 can limit the lower oil distribution plate 77 in the circumferential direction of the lower oil distribution plate 7, thereby preventing the lower oil distribution plate 77 from rotating due to the friction of the second blade.

[0038] In one embodiment of the present embodiment, a connecting bolt 23 is further included. A connecting through hole connecting the two sides of the bottom bracket 2 is provided on the bottom bracket 2. A mounting screw hole corresponding to the position of the connecting through hole is provided on the lower end surface of the upper cover 1. The connecting bolt 23 passes through the connecting through hole and is threadedly connected in the mounting screw hole. Connecting the bottom bracket 2 and the upper cover 1 by the connecting bolt 23 can make it easier to disassemble and install the housing.

[0039] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A hydraulic fluid anti-wear performance testing unit, characterized in that: include: The outer shell comprises a hollow cavity, a stator, a rotor, a large blade, a small blade, an upper oil distribution plate and a lower oil distribution plate. The inner shell comprises a hollow cavity. The lower oil distribution plate is fixedly connected to the bottom of the cavity. The stator is annular. The stator is fixedly connected to the upper end of the lower oil distribution plate. The upper oil distribution plate is fixedly connected to the upper end of the stator. The upper oil distribution plate, the stator and the lower oil distribution plate form a pump body. The rotor rotates around a first rotating shaft and is connected to the pump body. The first rotating shaft coincides with the central axis of the rotor. There is a distance between the central axis of the rotor and the central axis of the stator. The lower oil distribution plate divides the cavity into an oil suction area and an oil cavity. The oil cavity in the pump body forms an oil suction area. The oil pumping area, the oil cavity outside the pump body forms an oil outlet area, the lower oil distribution plate is provided with an oil inlet groove connecting the oil suction area and the oil pumping area; the upper oil distribution plate is provided with an oil outlet groove connecting the oil pumping area and the oil outlet area, the outer shell is provided with an oil inlet connecting the oil inlet area with the outside world and an oil outlet connecting the oil outlet with the outside world, the rotor is used to connect an external power source; the rotor is provided with a first type of groove and a second type of groove, the large blade is arranged in the first type of groove and can slide along the radial direction of the rotor as the rotor rotates, the small blade is detachably connected in the second type of groove, and the bottom of the small blade is in contact with the lower oil distribution plate.

2. The hydraulic fluid anti-wear performance testing unit according to claim 1, characterized in that: It also includes a fixing bolt, and the side of the rotor is provided with a fixing screw hole connecting the second type of groove with the outside world. The fixing bolt is screwed into the fixing screw hole and rests on the side of the small blade; the assembly method between the large blade and the first type of groove is clearance fit.

3. The hydraulic fluid anti-wear performance testing unit according to claim 1, characterized in that: It also includes an axial fixing member, which is fixedly installed in the second type of groove and located at the top of the small blade. The assembly method between the small blade and the second type of groove is interference fit, and the bottom of the axial fixing member contacts the top of the small blade.

4. The hydraulic fluid anti-wear performance testing unit according to claim 1, characterized in that: The first type grooves and the second type grooves are evenly spaced along the circumference of the rotor and the number of the first type grooves and the second type grooves is equal. Each of the first type grooves is provided with the large blade, and each of the second type grooves is provided with the small blade.

5. The hydraulic fluid anti-wear performance testing unit according to claim 1, characterized in that: It also includes a tenon bolt, which passes through the upper oil distribution plate, the stator and the lower oil distribution plate and fixes the upper oil distribution plate, the stator and the lower oil distribution plate together.

6. The hydraulic fluid anti-wear performance testing unit according to claim 1, characterized in that: The shell includes an upper cover and a bottom bracket, the lower end of the upper cover is detachably connected to the upper end of the bottom bracket, the oil inlet is arranged on the bottom bracket, the oil outlet is arranged on the upper cover, and the lower end of the bottom bracket is used to be connected to the hydraulic lifting platform.

7. The hydraulic fluid anti-wear performance testing unit according to claim 6, characterized in that: It also includes a drive shaft, and the upper cover and the upper oil distribution plate are both provided with mounting through holes. One end of the drive shaft passes through two of the mounting through holes and is detachably fixedly connected to the rotor through a driving positioning pin. The drive shaft is coaxially arranged with the rotor, and the drive shaft is used to connect to a power device.

8. The hydraulic fluid anti-wear performance testing unit according to claim 6, characterized in that: A mounting groove is provided on the upper side of the base, and the lower oil distribution plate is detachably fixedly connected in the mounting groove, the side wall of the lower oil distribution plate is fitted with the side wall of the mounting groove, and there is a gap between the bottom of the lower oil distribution plate and the inner bottom surface of the mounting groove, and the oil suction area is formed between the lower oil distribution plate and the inner bottom surface of the mounting groove.

9. The hydraulic fluid anti-wear performance testing unit according to claim 6, characterized in that: It also includes a lower positioning pin, a vertical first socket is arranged on the lower oil distribution plate, the axis of the first socket is spaced apart from the center axis of the lower oil distribution plate, a second socket connected to the first socket is arranged on the base, and the lower positioning pin is inserted into the first socket and the second socket.

10. The hydraulic fluid anti-wear performance testing unit according to claim 6, characterized in that: It also includes a connecting bolt. The base is provided with a connecting through hole connecting the two sides of the base, and the lower end surface of the upper cover is provided with a mounting screw hole corresponding to the position of the connecting through hole. The connecting bolt passes through the connecting through hole and is threadedly connected in the mounting screw hole.

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