Portable motor speed test device

Abstract

The invention relates to the technical field of motor detection, and discloses a portable motor speed test device, comprising a mounting seat, a measuring shaft, and an outer tube, wherein the mounting seat is fixedly connected to the outer tube, the measuring shaft is rotatably connected inside the outer tube, a hollow air pipe structure is provided inside the top of the measuring shaft, an air valve is installed inside the air pipe structure, a cavity is provided inside the outer tube, an air outlet is provided on the outer wall of the outer tube, an axial flow fan is coaxially fixed on the measuring shaft, a circulating air hole is provided at the bottom of the air pipe structure, a contact head is fixedly connected to the top of the measuring shaft, and a suction cup is fixed on the side of the contact head; the suction cup in the invention can be tightly attached to the surface of the motor shaft, thereby increasing the adhesion tightness between the suction cup and the motor shaft, and at the same time, the negative pressure is a dynamic adjustment, the higher the motor shaft speed, the stronger the negative pressure between the suction cup and the motor shaft is made by the axial flow fan, thereby avoiding the instability caused by the connection between the contact head and the motor shaft, and the process of connecting with the motor shaft is simple, the volume is small and easy to carry.

Description

Technical Field

[0001] The invention relates to the technical field of motor detection, and in particular to a portable motor speed testing device. Background Art

[0002] The handheld centrifugal tachometer is a commonly used instrument in the machinery industry. It is mainly used to measure the speed, linear speed or frequency of the motor. It is widely used in the manufacturing industries of motors, electric fans, papermaking, plastics, chemical fibers, washing machines, automobiles, aircraft, ships, etc. It works on the principle of the centrifugal force of the rotating mass and the rotation angle or ratio. When the shaft of the tachometer rotates, the weight on the centrifuge leaves the axis under the action of the inertial centrifugal force, and drives the needle to rotate through the transmission device, thereby indicating the speed value. The handheld centrifugal tachometer has the characteristics of simple structure and easy use. It is one of the important tools for measuring the speed of the motor.

[0003] However, during use, the existing handheld centrifugal tachometers have a measuring head that needs to be in direct contact with or installed together with the motor to be measured. For example, Chinese patent CN201540293U discloses a handheld centrifugal tachometer, including a centrifugal speed measuring device, a case, a dial, a pointer, a locking device, and a movement gear for driving the pointer to rotate. The measuring head needs to be in direct contact with the motor to be measured, and the measuring head will be affected by factors such as the material, shape, and vibration of its contact surface. If the motor speed is high, these factors will cause the measuring head to be unable to closely follow the rotation of the shaft, thereby causing slippage. If the measuring head is connected to the motor to be measured using a flexible shaft, the flexible shaft requires an additional fixing device during installation, and secondly, the flexible shaft has a certain volume and weight, which increases the difficulty of carrying and transporting. In situations where the measuring equipment needs to be frequently moved or carried, the flexible shaft is cumbersome to use. At the same time, due to its softness and flexibility, the flexible shaft may be damaged or deformed during carrying and use. Summary of the invention

[0004] (I) Technical problems to be solved: In view of the deficiencies in the prior art, the present invention provides a portable motor speed test device, which has the advantages of being easy to carry and use, and not prone to slipping during the speed test. This solves the problem that the measuring head of the existing tachometer is prone to slipping when testing high-speed motors, and the flexible shaft is not easy to carry.

[0005] (II) Technical solution: In order to achieve the above-mentioned purpose of being easy to carry and use, and not easy to slip during the speed test, the present invention provides the following technical solution: a portable motor speed test device, comprising a mounting seat, a measuring shaft, and an outer tube, the mounting seat is fixedly connected to the outer tube, the measuring shaft is rotatably connected to the outer tube, a hollow air pipe structure is opened in the top of the measuring shaft, an air valve is installed in the air pipe structure, a cavity is opened in the outer tube, and a plurality of air outlet holes connected to the cavity are opened on the outer wall of the outer tube, an axial flow fan is coaxially fixedly connected to the measuring shaft at the position of the cavity, a plurality of circulating air holes connected to the top of the cavity are opened at the bottom of the air pipe structure, an annular contact head is fixedly connected to the top of the measuring shaft, and an annular suction cup is fixedly installed on the side of the contact head, when the measuring shaft rotates, the axial flow fan is driven to rotate and extract the gas in the cavity and the air pipe structure, so that negative pressure is generated between the suction cup and the contact head and the object to be measured.

[0006] Preferably, the air valve comprises a cylindrical fixed shell, wherein the upper and lower ends of the fixed shell are fixedly provided with limiting disks, the limiting disk is coaxially slidably installed with a valve stem, the valve stem is fixedly installed with a valve plate, an annular baffle is fixedly provided between the upper and lower limiting disks, the inner diameter of the annular baffle is smaller than the diameter of the valve plate, the lower surface of the annular baffle is in contact with the upper surface of the valve plate, and a spring is provided between the valve plate and the limiting disk at the lower end, the valve plate is also provided with a plurality of groups of sliding baffles that can slide along the radial direction of the valve plate along its circumferential direction, an elastic component is provided between the sliding baffle and the valve plate, a plurality of through holes penetrating the annular baffle are opened on the annular baffle along its circumferential direction, and the sliding baffle closes the through hole when it slides out; when the air valve rotates following the measuring shaft, the sliding baffle slides out due to the centrifugal force and closes the through hole; when the measuring shaft stops rotating, the sliding baffle is pulled back by the elastic component, and the through hole opens.

[0007] Preferably, a rubber ring is fixedly mounted on the top of the contact head, and a plurality of ventilation grooves are provided on the rubber ring, one end of the ventilation groove is connected to the air pipe structure, and the other end of the ventilation groove is connected to the suction cup position.

[0008] Preferably, a gap is left between the upper end surface and the lower end surface of the axial flow fan and the cavity.

[0009] Preferably, a plurality of limiting protrusions are arranged on the side surface of the valve stem, and a limiting groove matching the limiting protrusions is arranged on the limiting disk.

[0010] Preferably, the upper surfaces of the valve plate and the sliding baffle are both provided with rubber material, and the lower surface of the annular baffle is provided with rubber material.

[0011] Preferably, the suction cup is connected to the contact head via a snap-fit.

[0012] Preferably, an annular raised layer is provided on the lower surface of the annular baffle at a position larger than the diameter of the valve plate, and the raised layer is in contact with the upper surface of the sliding baffle that slides out.

[0013] (III) Beneficial effects: Compared with the prior art, the present invention provides a portable motor speed test device, which has the following beneficial effects: 1. The portable motor speed test device, through the coordinated use of the axial flow fan structure and the suction cup structure, enables the measuring shaft to rotate during its rotation, and the axial flow fan will rotate together and extract the air in the top gap, so that negative pressure is formed between the trachea structure and the suction cup and the motor shaft, so that the suction cup is tightly attached to the surface of the motor shaft, thereby increasing the adhesion between the suction cup and the motor shaft, and at the same time, this negative pressure will increase with the increase of the speed of the motor shaft, which makes the connection between the contact head and the motor shaft a dynamic adjustment, and the tightness of the connection between the contact head and the motor shaft changes with the change of the motor shaft speed, that is, the higher the motor shaft speed, the stronger the negative pressure between the suction cup and the motor shaft made by the axial flow fan, and the tighter and more stable the connection between the contact head and the motor shaft, thereby avoiding the test error caused by the unstable slippage of the connection between the contact head and the motor shaft; and this structure is simple in the process of connecting with the motor shaft, and at the same time, it is small in size, not easy to bend, and easy to carry.

[0014] 2. The portable motor speed test device, through the coordinated use of the annular baffle structure and the valve plate structure, can prevent the air pressure inside the suction cup from rising when the axial flow fan can no longer maintain the negative pressure of the suction cup, and ensure that when the motor switches from high-speed rotation to low-speed rotation, the contact head is also tightly attached to the motor shaft. Only when the centrifugal force generated by the sliding baffle when the measuring shaft rotates is less than the elastic force of the elastic component, the contact head can be removed from the motor shaft. This design not only makes it easier to remove the contact head from the motor shaft when the motor stops testing, but also ensures that in the test of motors with frequently changing speeds, the dynamic adjustment function of the air valve can ensure that the connection between the contact head and the motor shaft remains tight and stable at different speeds, thereby improving the accuracy and reliability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the three-dimensional structure of the portable motor speed test device in the present invention.

[0016] Figure 2 It is a structural front view of the portable motor speed test device in the present invention.

[0017] Figure 3 It is a top view of the structure of the portable motor speed test device in the present invention.

[0018] Figure 4 for Figure 3 AA section view.

[0019] Figure 5 for Figure 4 Middle BB section view.

[0020] Figure 6 It is a schematic diagram of the valve plate structure of the portable motor speed testing device in the present invention.

[0021] Figure 7 for Figure 4 Partially enlarged view N.

[0022] Figure 8 for Figure 4 Partially enlarged view M.

[0023] Fig. 9 It is a schematic diagram of the structure of the sliding baffle of the portable motor speed test device in the present invention.

[0024] Fig.10 This is a schematic diagram of the air valve structure of the portable motor speed test device in the present invention when it is open.

[0025] Fig.11 It is a schematic diagram of the three-dimensional structure of the axial flow fan of the portable motor speed test device in the present invention.

[0026] Fig.12 This is a sectional view of the three-dimensional structure of the contact head of the portable motor speed test device in the present invention.

[0027] Fig.13 It is a three-dimensional structural cross-sectional view of the axial flow fan of the portable motor speed test device in the present invention.

[0028] In the figure: 1. mounting base; 2. outer tube; 21. cavity; 22. air outlet; 3. measuring axis; 31. axial flow fan; 32. air pipe structure; 33. circulation air hole; 4. contact head; 41. rubber ring; 42. ventilation groove; 43. suction cup; 5. air valve; 51. fixed shell; 52. limiting disk; 53. valve stem; 54. annular baffle; 55. spring; 56. through hole; 57. limiting protrusion; 6. valve plate; 61. sliding baffle; 62. elastic component. DETAILED DESCRIPTION

[0029] 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.

[0030] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 7 , Figure 8 , Fig.11 , Fig.12 , Fig.13 , a portable motor speed test device comprises a mounting base 1, a measuring shaft 3, and an outer tube 2, wherein the mounting base 1 is fixedly connected to the outer tube 2, and the measuring shaft 3 is rotatably connected inside the outer tube 2, the fixed mounting base 1 and the outer tube 2 ensure the stability of the entire device, and the measuring shaft 3 can rotate freely, thereby effectively transmitting the speed of the motor being tested. A hollow air pipe structure 32 is provided in the top of the measuring shaft 3, and the hollow air pipe structure 32 is used for the passage of air flow so as to control the internal air pressure during the measurement process. This helps to form a negative pressure between the suction cup 43 and the motor shaft, thereby enhancing the adhesion. An air valve 5 is installed in the air pipe structure 32, and the air valve 5 is designed to dynamically adjust the air flow and air pressure in the air pipe. By controlling the on and off of the air flow, the air valve 5 can maintain the negative pressure of the suction cup 43 under different operating conditions to ensure a stable connection. A cavity 21 is provided in the outer tube 2, and the cavity 21 provides a space for the circulation and regulation of the air flow, helping to form the required negative pressure conditions. The outer wall of the outer tube 2 is provided with a plurality of air outlet holes 22 connected to the cavity 21. The air outlet holes 22 allow the extracted air to be discharged, thereby helping to form a negative pressure between the cavity 21 and the suction cup 43. An axial flow fan 31 is coaxially fixedly connected to the measuring shaft 3 at the position of the cavity 21. The function of the axial flow fan 31 is to extract the air in the cavity 21 and promote the formation of negative pressure. It works together with the rotation of the measuring shaft 3 to adapt to different speed conditions. The bottom of the air pipe structure 32 is provided with a plurality of circulation air holes 33 connected to the top of the cavity 21. These circulation air holes 33 allow the air flow to circulate between the air pipe and the cavity 21 to maintain and adjust the negative pressure. An annular contact head 4 is fixedly connected to the top of the measuring shaft 3. An annular suction cup 43 is fixedly installed on the side of the contact head 4. The annular contact head 4 provides a uniform contact surface that can better fit the surface of the object to be measured, especially in the case of a circular shaft. In addition, the design of the annular suction cup 43 utilizes the negative pressure principle, so that the suction cup 43 can be firmly attached to the surface of the object to be measured. The negative pressure enhances the adsorption force, ensuring that the connection between the contact head 4 and the motor shaft remains stable when the motor speed changes. When the measuring shaft 3 rotates, the axial flow fan 31 is driven to rotate and extract the gas in the cavity 21 and the air pipe structure 32, so that negative pressure is generated between the suction cup 43 and the contact head 4 and the object to be measured.

[0031] See also Figure 4 , Figure 5 , Figure 7 , Fig. 9 , Fig.11 and Fig.12The air valve 5 includes a cylindrical fixed shell 51, and a limiting disk 52 is fixedly provided at the upper and lower ends of the fixed shell 51. The cylindrical fixed shell 51 provides a structural frame of the air valve 5, and the limiting disk 52 is used to limit the movement range of the valve stem 53, ensuring that the valve stem 53 and the valve plate 6 can slide on the designed trajectory, thereby effectively opening or closing the airflow channel. A valve stem 53 is coaxially slidably installed in the limiting disk 52. The valve stem 53 is a driving component for the movement of the valve plate 6. By sliding in the limiting disk 52, the valve stem 53 can drive the valve plate 6 to open and close operations to control the passage of airflow. A valve plate 6 is fixedly installed on the valve stem 53. The valve plate 6 is a key component for controlling the opening or closing of the airflow channel. By connecting with the valve stem 53, the valve plate 6 can effectively open or close the airflow when the valve stem 53 moves. When the air valve 5 is opened, Fig.10 As shown, an annular baffle 54 is fixedly arranged between the upper and lower limiting disks 52. The inner diameter of the annular baffle 54 is smaller than the diameter of the valve disc 6. The design purpose of the annular baffle 54 is to limit the maximum range of motion of the valve disc 6. The inner diameter is smaller than the diameter of the valve disc 6 to ensure that when the valve disc 6 is fully closed, the airflow can be effectively blocked. The lower surface of the annular baffle 54 contacts the upper surface of the valve disc 6. This contact design ensures that when the valve disc 6 is closed, an effective seal can be formed to prevent airflow leakage, thereby maintaining negative pressure. A spring 55 is arranged between the valve disc 6 and the lower limiting disk 52. The spring 55 provides a reverse force. When the external suction force decreases, the spring 55 force causes the valve disc 6 to return to the closed position to prevent the air pressure from rising and ensure that the adsorption force continues. The valve disc 6 is also provided with a plurality of groups of sliding baffles 61 that can slide along the radial direction of the valve disc 6 along its circumferential direction. An elastic component 62 is arranged between the sliding baffle 61 and the valve disc 6. The sliding baffle 61 can slide under the action of centrifugal force to close or open the through hole 56. The elastic component 62 ensures that when there is no centrifugal force, the sliding baffle 61 can be reset to maintain the open or closed state of the through hole 56. The annular baffle 54 is provided with a plurality of through holes 56 penetrating the annular baffle 54 along its circumferential direction. When the sliding baffle 61 slides out, the through holes 56 are closed. Fig. 9 As shown; when the air valve 5 rotates with the measuring shaft 3, the sliding baffle 61 slides out due to the centrifugal force and closes the through hole 56; when the measuring shaft 3 stops rotating, the sliding baffle 61 is pulled back by the elastic component 62, and the through hole 56 is opened.

[0032] See also Figure 4 , Figure 7 and Fig.13A rubber ring 41 is fixedly installed on the top of the contact head 4. Installing the rubber ring 41 on the top of the contact head 4 helps to increase the friction between the contact head 4 and the motor shaft. It prevents the contact head 4 from sliding when the motor shaft rotates at high speed. At the same time, the rubber ring 41 can also play a certain buffering role and reduce vibration and wear. A number of ventilation grooves 42 are provided on the rubber ring 41. One end of the ventilation groove 42 is connected to the air pipe structure 32, and the other end of the ventilation groove 42 is connected to the position of the suction cup 43. The ventilation grooves 42 are provided on the rubber ring 41 to ensure gas circulation between the suction cup 43 and the air pipe structure 32. This design allows air to flow through the ventilation grooves 42 when the axial flow fan 31 is running, thereby effectively forming a negative pressure. At the same time, a number of ventilation grooves 42 also help to increase the surface roughness of the rubber ring 41, thereby increasing the friction between the rubber ring 41 and the motor shaft. Please refer to Figure 8 and Fig.13 , the upper and lower end surfaces of the axial flow fan 31 are both spaced apart from the cavity 21. This ensures that the air can flow smoothly, thereby improving the exhaust efficiency of the fan. The suction cup 43 is connected to the contact head 4 by a snap. The snap connection between the suction cup 43 and the contact head 4 is a design that is easy to disassemble. This connection method allows the user to replace the suction cup 43 of different sizes according to different motor shaft diameters to meet different measurement requirements.

[0033] See also Figure 6 , Fig. 9 and Fig.10 , a plurality of limiting protrusions 57 are arranged on the side of the valve stem 53, and a limiting groove matching the limiting protrusion 57 is arranged on the limiting disk 52. This is to prevent the valve stem 53 and the valve plate 6 from rotating together when the gas valve 5 rotates with the measuring shaft 3. This design can ensure that the valve stem 53 only slides in the axial direction and does not deviate during the rotation process. The upper surfaces of the valve plate 6 and the sliding baffle 61 are both provided with rubber material, and the lower surface of the annular baffle 54 is provided with rubber material. The rubber material can enhance the sealing effect. The rubber material has good elasticity and sealing performance, and can form a tight seal between the contact surfaces to prevent gas leakage and improve the negative pressure holding capacity of the entire device. An annular protrusion layer is arranged on the lower surface of the annular baffle 54 at a position larger than the diameter of the valve plate 6, and the protrusion layer contacts the upper surface of the sliding baffle 61 that slides out. In this way, it can be ensured that the sliding baffle 61 and the annular baffle 54 can fit tightly and improve the sealing performance.

[0034] Working principle: The device is installed on a centrifugal tachometer, wherein the measuring shaft 3 is connected to the transmission of the centrifugal tachometer. When in use, the contact head 4 is connected to the motor shaft of the motor to be measured, and the suction cup 43 is attached to the surface of the motor shaft. During the rotation of the motor shaft, the measuring shaft 3 is driven to rotate together through the contact head 4, and the axial flow fan 31 rotates together with the measuring shaft 3. During the rotation of the axial flow fan 31, the air between the top and the cavity 21 is extracted and discharged from the air outlet 22 around the bottom gap. When the air in the top gap is extracted, a negative pressure is formed between the trachea structure 32 and the suction cup 43 and the motor shaft, that is, the air pressure inside the suction cup 43 is lower than the external atmospheric pressure, and the external atmospheric pressure will produce an inward pressure on the suction cup 43. This inward pressure acts on the suction cup 43, so that the suction cup 43 is closely attached to the surface of the motor shaft, thereby increasing the adhesion tightness between the suction cup 43 and the motor shaft. At the same time, the negative pressure will increase with the increase of the rotation speed of the motor shaft, which makes the connection between the contact head 4 and the motor shaft a dynamic adjustment. The tightness of the connection between the contact head 4 and the motor shaft changes with the change of the motor shaft rotation speed. When the motor shaft rotation speed is high, the axial flow fan 31 increases the negative pressure between the suction cup 43 and the motor shaft, and the connection between the contact head 4 and the motor shaft is tighter and more stable, avoiding the test error caused by the unstable slippage of the contact head 4 and the motor shaft during the high-speed rotation of the motor shaft.

[0035] The air valve 5 structure provided in the air pipe structure 32 can prevent the air pressure inside the suction cup 43 from rising when the axial flow fan 31 can no longer maintain the negative pressure of the suction cup 43, thereby maintaining the adsorption force between the suction cup 43 and the motor shaft. When the suction force generated by the axial flow fan 31 is greater than the elastic force of the spring 55, the air valve 5 will open and connect the air pipe structure 32 with the suction cup 43; and when the suction force generated by the axial flow fan 31 is less than the elastic force of the spring 55, the air valve 5 will close and form a relatively closed cavity between the suction cup 43 and the motor shaft to maintain the adsorption force, ensuring that when the motor switches from high-speed rotation to low-speed rotation, the contact head 4 is also tightly attached to the motor shaft, and during the rotation, the sliding baffle 61 will be subjected to centrifugal force. The valve plate 6 slides outward in the circumferential direction. If the suction force generated by the axial fan 31 is less than the elastic force of the spring 55, the valve plate 6 contacts the annular baffle 54, and the sliding baffle 61 sliding outward will close the through hole 56 to prevent the suction cup 43 from releasing pressure. Only when the centrifugal force generated by the sliding baffle 61 is less than the elastic force of the elastic component 62 when the measuring shaft 3 rotates, the elastic component 62 will pull the sliding baffle 61 back, so that the suction cup 43 releases pressure, and the contact head 4 can be removed from the motor shaft. This design not only makes it easier to remove the contact head 4 from the motor shaft when the motor stops testing, but also ensures that in the motor test with frequent changes in speed, the dynamic adjustment function of the air valve 5 can ensure that the connection between the contact head 4 and the motor shaft remains tight and stable at different speeds, thereby improving the accuracy and reliability of the test.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A portable motor speed test device, comprising a mounting base (1), a measuring shaft (3), and an outer tube (2), wherein the mounting base (1) is fixedly connected to the outer tube (2), and the measuring shaft (3) is rotatably connected inside the outer tube (2), characterized in that: A hollow air pipe structure (32) is provided in the top of the measuring shaft (3), an air valve (5) is installed in the air pipe structure (32), a cavity (21) is provided in the outer tube (2), a plurality of air outlet holes (22) in communication with the cavity (21) are provided on the outer wall of the outer tube (2), an axial flow fan (31) is coaxially fixedly connected to the measuring shaft (3) at the position of the cavity (21), a plurality of circulation air holes (33) in communication with the top of the cavity (21) are provided at the bottom of the air pipe structure (32), an annular contact head (4) is fixedly connected to the top of the measuring shaft (3), an annular suction cup (43) is fixedly installed on the side of the contact head (4), and when the measuring shaft (3) rotates, the axial flow fan (31) is driven to rotate and extract gas in the cavity (21) and the air pipe structure (32), so that negative pressure is generated between the suction cup (43) and the contact head (4) and the object to be measured.

2. The portable motor speed test device according to claim 1, characterized in that: The air valve (5) comprises a cylindrical fixed shell (51), wherein the upper and lower ends of the fixed shell (51) are fixedly provided with limiting disks (52), wherein a valve stem (53) is coaxially slidably mounted in the limiting disk (52), wherein a valve plate (6) is fixedly mounted on the valve stem (53), and an annular baffle (54) is fixedly mounted between the limiting disks (52) at the upper and lower ends, wherein the inner diameter of the annular baffle (54) is smaller than the diameter of the valve plate (6), wherein the lower surface of the annular baffle (54) is in contact with the upper surface of the valve plate (6), and a spring (55) is arranged between the valve plate (6) and the limiting disk (52) at the lower end, and wherein the valve plate (6) is also provided with a spring (55) along its circumferential direction which can move along the valve plate (6) There are a plurality of groups of sliding baffles (61) sliding in the radial direction, an elastic component (62) is arranged between the sliding baffle (61) and the valve plate (6), and a plurality of through holes (56) penetrating the annular baffle (54) are provided on the annular baffle (54) along its circumferential direction, and the through holes (56) are closed when the sliding baffle (61) slides out; when the air valve (5) rotates following the measuring shaft (3), the sliding baffle (61) slides out due to the centrifugal force and closes the through holes (56); when the measuring shaft (3) stops rotating, the sliding baffle (61) is pulled back by the elastic component (62), and the through holes (56) are opened.

3. The portable motor speed test device according to claim 1, characterized in that: A rubber ring (41) is fixedly mounted on the top of the contact head (4), and a plurality of ventilation grooves (42) are provided on the rubber ring (41), one end of the ventilation groove (42) is connected to the air pipe structure (32), and the other end of the ventilation groove (42) is connected to the position of the suction cup (43).

4. The portable motor speed test device according to claim 1, characterized in that: A gap is left between the upper end surface and the lower end surface of the axial flow fan (31) and the cavity (21).

5. The portable motor speed test device according to claim 2, characterized in that: A plurality of limiting protrusions (57) are provided on the side of the valve stem (53), and a limiting groove matching the limiting protrusions (57) is provided on the limiting disk (52).

6. The portable motor speed test device according to claim 2, characterized in that: The upper surfaces of the valve plate (6) and the sliding baffle plate (61) are both provided with rubber material, and the lower surface of the annular baffle plate (54) is provided with rubber material.

7. The portable motor speed test device according to claim 1, characterized in that: The suction cup (43) and the contact head (4) are connected via a buckle.

8. The portable motor speed test device according to claim 2, characterized in that: An annular raised layer is provided on the lower surface of the annular baffle (54) at a position larger than the diameter of the valve plate (6), and the raised layer is in contact with the upper surface of the sliding baffle (61) that has slid out.

Images