Ultrasonic gas meter pulsating flow detection device

Abstract

The utility model discloses a pulsating flow detection device for an ultrasonic gas meter, which belongs to the technical field of ultrasonic gas meters and comprises a fan and a test tube fixedly arranged at the output end of the fan, a flow test device is mounted on the test tube, and two sliding sleeves are slidably arranged on the test tube on the right of the flow test device along the left-right direction. The outer surface of the sliding sleeve is rotationally connected with a mounting sleeve. When the ultrasonic gas meter testing device is used for testing an ultrasonic gas meter, the sensors are fixed through the sensor fixing devices, then the two sensors are located on the same side of the testing pipe through rotation of the mounting sleeve, then the distance between the two sensors is adjusted through the sliding sleeve, then the fan blows air into the testing pipe for testing, and after testing is completed, the testing efficiency is greatly improved. And one sensor is driven to rotate by 180 degrees by rotating the mounting sleeve, so that a second mounting mode of the sensor is realized, and then the test is performed, thereby achieving the purposes of conveniently fixing the sensor and debugging the position of the sensor.

Description

Technical Field

[0001] The utility model relates to the technical field of ultrasonic gas meters, in particular to a pulsating flow detection device for ultrasonic gas meters. Background Art

[0002] An ultrasonic gas meter is a gas meter that uses the propagation characteristics of ultrasound for measurement. Its working principle is to measure the time difference when the gas is transmitted in the pipeline, thereby calculating the flow rate of the gas. Specifically, when ultrasound propagates in the fluid, it is accelerated when it is downstream and decelerated when it is upstream. The time difference measured by the sensor is proportional to the flow rate of the fluid, so the flow rate of the fluid can be calculated. The flow rate is combined with the known cross-sectional area of ​​the pipeline to calculate the volume flow rate over time.

[0003] After searching, the patent number is: CN113267239A, which provides a pulsation detection device for an ultrasonic gas meter and discloses the following technical solutions, including a workbench, on which a fan, a support frame, a pipeline, a control display, a solenoid valve, an ultrasonic gas meter standard part, and an ultrasonic gas meter to be tested are placed. Mounting frames are provided on both sides of the workbench, and a fixing frame is connected between the tops of the two mounting frames. A driving device is installed on one side of the fixing frame, and a driving screw is connected to the output end of the driving device. A mounting seat is connected to the driving screw, and the bottom of the mounting seat extends to the top of the fixing frame and is connected to a heat dissipation fan. During detection, the present invention can allow the heat dissipation fan to dissipate heat from the fan and the pipeline, avoid hot air passing through the pipeline where the detection gas flows, and increase the accuracy of detection. The fan works and inhales air through the air inlet for detection, which reduces the power generated by blowing, thereby saving losses.

[0004] The existing ultrasonic gas meter generally has at least two sensors that can emit and receive ultrasonic waves. In the production of ultrasonic gas meters, it is necessary to perform pulsation detection on the ultrasonic gas meter to improve the qualified rate. The existing detection method is to fix the sensor on the test tube, then blow air into the test tube, test the flow of the gas in the test tube through the sensor, and then compare it with the flow tested by the standard measuring device set on the test tube. If the error exceeds the set range, it is unqualified, and if the error is within the set range, it is qualified. When fixing the sensor, the distance between the two sensors needs to be adjusted so that the ultrasonic waves emitted by the two sensors can be received by the other party. The sensors are usually fixed with cable ties. Although the fixing method is simple, the distance between the two sensors is not easy to adjust. It is necessary to continuously verify whether the distance between the two sensors is appropriate. At the same time, there are two installation methods for the two sensors when they are working. The first is to install the two sensors on the same side of the test tube, and the second is to install the two sensors on both sides of the test tube. The existing fixing method is not convenient for switching between the two fixing methods, which affects the efficiency of the test. Utility Model Content

[0005] The purpose of the utility model is to provide an ultrasonic gas meter pulsation flow detection device, which can conveniently fix the sensor and adjust the distance between two sensors, and solve the problem of mutual conversion between two fixing modes of the sensor.

[0006] The utility model adopts the following technical scheme: an ultrasonic gas meter pulsation flow detection device, including a fan, and a test tube fixedly arranged at the output end of the fan, a flow test device installed on the test tube, two sliding sleeves are slidably arranged on the right side of the flow test device along the left and right directions on the test tube, the outer surface of the sliding sleeve is rotatably connected with a mounting sleeve, a sensor fixing device is arranged on the mounting sleeve, and the sensor fixing device is used to fix the ultrasonic sensor so that the bottom end of the sensor fits with the outer surface of the test tube.

[0007] Furthermore, the sensor fixing device includes a base plate fixed to the outer surface of the mounting sleeve, the upper end surface of the base plate is provided with a slide groove along the front-to-back direction, two L-clamps are slidably arranged in the slide groove, a transmission chamber is provided on the inner bottom wall of the slide groove along the front-to-back direction, and a driving device is arranged in the transmission chamber.

[0008] Furthermore, the driving device includes a bidirectional threaded rod located in the transmission chamber and rotatably connected to the base plate, and transmission blocks are respectively threadedly connected to the two threads of the bidirectional threaded rod, and each transmission block is fixedly arranged with a corresponding L-clamp.

[0009] Furthermore, the outer surface of the mounting sleeve is provided with a guide groove along the left and right directions, and a locking pin is provided on the mounting sleeve for sliding through the guide groove. The right side surface of the sliding sleeve extends to the right side of the mounting sleeve and is coaxially fixed with a locking ring, and a plurality of locking grooves matching the locking pin are evenly provided on the locking ring along the circumference.

[0010] Furthermore, a locking bolt is threadedly connected between two adjacent locking grooves on the locking ring, and the bottom end of the locking bolt contacts the outer surface of the test tube.

[0011] Furthermore, the front end of the bidirectional threaded rod extends to the outside of the bottom plate and is fixedly provided with a rotating portion, and a locking nut is threadedly connected to the bidirectional threaded rod located on the outside of the bottom plate.

[0012] Furthermore, a fixing plate is rotatably connected to the junction of the two sections of the thread of the bidirectional threaded rod, and the fixing plate is fixed to the inner bottom wall of the transmission chamber.

[0013] Furthermore, a locking spring is arranged in the guide groove, the left end of the locking spring is fixed to the inner wall of the locking groove, the right end of the locking spring is fixed to the left side of the locking pin, and the locking spring pushes the locking pin to always move to the right.

[0014] Furthermore, a slide rail is fixedly arranged on the test tube in the left and right directions, and the two sliding sleeves are slidably arranged with the test tube left and right through the limiting grooves and the slide rails provided on the inner wall.

[0015] Furthermore, the middle section of the test tube is provided with a bracket and a base of the fan, which are fixedly arranged on the base plate below.

[0016] 1. The utility model sets a sliding sleeve, a mounting sleeve and a sensor fixing device. When testing the ultrasonic gas meter, the sensor is fixed by the sensor fixing device, and then the mounting sleeve is rotated so that the two sensors are located on the same side of the test tube. Then the distance between the two sensors is adjusted by the sliding sleeve, and then the fan is used to blow air into the test tube for testing. After the test is completed, one of the sensors is driven to rotate 180 degrees by rotating the mounting sleeve, thereby realizing the second installation method of the sensor. Then the test is carried out, thereby achieving the purpose of conveniently fixing the sensor and adjusting the position of the sensor.

[0017] 2. The utility model sets an L-clamp and a bidirectional threaded rod. When fixing the sensor, the mounting plate of the sensor is placed between the two L-clamps, and then the two-way threaded rod drives the two L-clamps to move closer, so that the two L-clamps clamp the mounting plate, thereby fixing the sensor and achieving the purpose of conveniently fixing the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the utility model;

[0019] Figure 2 This is a schematic diagram of the front view structure of the utility model;

[0020] Figure 3 It is a schematic diagram of the three-dimensional structure of the test tube in the utility model;

[0021] Figure 4 It is a schematic diagram of the three-dimensional structure of the sensor in the utility model;

[0022] Figure 5 It is a schematic diagram of the three-dimensional structure of the installation sleeve in the utility model;

[0023] Figure 6 It is a schematic diagram of the three-dimensional structure of the bottom plate in the utility model;

[0024] Figure 7 For the utility model Figure 6 A schematic diagram of the structure enlargement at point A;

[0025] Figure 8 It is a schematic diagram of the three-dimensional structure of the sliding sleeve in the utility model;

[0026] Fig. 9 It is a schematic diagram of the internal three-dimensional structure of the sensor in the utility model;

[0027] Fig.10 This is a schematic diagram of the second installation method of the two sensors in the utility model;

[0028] Fig.11 This is a schematic diagram of the structure of the first installation method of the two sensors in the utility model.

[0029] In the figure, 1, sensor; 2, operation box; 3, mounting plate; 4, transmitter; 5, fan; 6, test tube; 7, flow test device; 8, sliding sleeve; 9, mounting sleeve; 10, bottom plate; 11, slide groove; 12, L clamping plate; 13, transmission chamber; 14, two-way threaded rod; 15, transmission block; 16, rotating part; 17, locking nut; 18, fixing plate; 19, guide groove; 20, locking pin; 21, locking ring; 22, locking groove; 23, locking spring; 24, locking bolt; 25, slide rail; 26, bracket; 27, base plate. DETAILED DESCRIPTION

[0030] The present invention is described in detail below with reference to the accompanying drawings and embodiments:

[0031] See also Figure 1-11 The ultrasonic gas meter pulsation flow detection device described in the utility model, the existing ultrasonic gas meter includes two sensors 1 and an operation box 2, the sensor 1 is electrically connected to the operation box 2 through a wire, a mounting plate 3 is fixedly arranged at the bottom end of the sensor 1, and an ultrasonic transmitter 4 is arranged inside the sensor 1, and the transmitter 4 can receive ultrasonic waves while transmitting ultrasonic waves. When in use, the sensor 1 is installed on the pipeline of the fluid, and the distance between the two sensors 1 is adjusted so that the ultrasonic wave emitted by the transmitter 4 of the upstream sensor 1 enters the pipeline, passes through the fluid, and is reflected by the inner wall of the pipeline to the transmitter 4 of the downstream sensor 1, and the ultrasonic wave emitted by the transmitter 4 of the downstream sensor 1 can also be reflected to the transmitter 4 of the upstream sensor 1. When the fluid in the pipeline does not flow, the bidirectional transmission time of the ultrasonic wave between the upstream and downstream is the same. Once the fluid flows in the pipeline, the ultrasonic wave is accelerated in the downstream and decelerated in the reverse flow, so that the ultrasonic wave has different transmission times. The time difference measured by the sensor 1 is proportional to the fluid flow rate in the pipeline. Together with the known pipeline cross section, the actual volume flow rate can be calculated and output on the display screen on the operation box 2.

[0032] See also Figure 1-11The ultrasonic gas meter pulsation flow detection device described in the utility model includes a fan 5 and a test tube 6 fixedly arranged at the output end of the fan 5. A flow test device 7 is installed on the test tube 6. The flow test device 7 is a standard part that has been calibrated. The flow tested by the flow test device 7 is used as a standard. Two sliding sleeves 8 are slidingly arranged on the right side of the flow test device 7 along the left and right directions on the test tube 6. The outer surface of the sliding sleeve 8 is rotatably connected with a mounting sleeve 9. A sensor fixing device is arranged on the mounting sleeve 9. The sensor fixing device is used to fix the ultrasonic sensor 1 so that the bottom end of the sensor 1 fits with the outer surface of the test tube 6.

[0033] When in use, the two sensors 1 of the ultrasonic gas meter are respectively fixed on the sensor fixing devices, and the two sensor 1 fixing devices are located on the same side of the test tube 6 by rotating the installation sleeve 9. Then, the distance between the two ultrasonic sensors 1 is adjusted by the sliding sleeve 8, so that the ultrasonic wave emitted by the transmitter 4 of the upstream sensor 1 enters the pipeline, passes through the fluid, and is reflected by the inner wall of the pipeline to the transmitter 4 of the downstream sensor 1. The ultrasonic wave emitted by the transmitter 4 of the downstream sensor 1 can also be reflected to the transmitter 4 of the upstream sensor 1. Then, the fan 5 is started to blow air into the test tube 6. By comparing the time for the ultrasonic wave to be transmitted from the upstream sensor 1 to the downstream sensor 1 and the time for the ultrasonic wave to be transmitted from the downstream sensor 1 to the upstream sensor 1, the flow rate of the fluid in the pipeline can be calculated. The flow rate can be calculated based on the inner diameter of the pipeline and output on the display screen on the operating box 2, and then compared with the flow rate tested by the flow test device 7, if the error is within the set range, it is qualified, and if the error exceeds the set range, it is unqualified; then by rotating the installation sleeve 9, the installation sleeve 9 drives the sensor 1 fixing device to rotate 180 degrees, and then the corresponding sensor 1 rotates 180 degrees. At this time, the ultrasonic wave emitted by the transmitter 4 of one of the sensors 1 passes through the wall of the test tube 6, passes through the fluid, and then passes through the wall of the test tube 6 again to the transmitter 4 of the other sensor 1. After comparing the two-way transmission time of the transmitters 4 of the two sensors 1, the flow rate is calculated in combination with the known cross-sectional area of ​​the test tube 6, and compared with the flow rate tested by the flow test device 7, if the error is within the set range, it is qualified, and if the error exceeds the set range, it is unqualified.

[0034] In this embodiment, the sensor 1 fixing device includes a base plate 10 fixed to the outer surface of the mounting sleeve 9, and a slide groove 11 is provided on the upper end surface of the base plate 10 along the front-to-back direction. Two L-clamps 12 are slidably arranged in the slide groove 11. A transmission chamber 13 is provided on the inner bottom wall of the slide groove 11 along the front-to-back direction. A driving device is arranged in the transmission chamber 13. The driving device is used to drive the two L-clamps 12 to move closer or farther, so as to achieve the purpose of clamping and loosening the mounting plate 3 of the sensor 1 by the two L-clamps 12, thereby achieving the purpose of fixing and removing the sensor 1 from the test tube 6.

[0035] In this embodiment, the driving device includes a bidirectional threaded rod 14 located in the transmission chamber 13 and rotatably connected to the base plate 10. Transmission blocks 15 are respectively threadedly connected to the two threaded sections of the bidirectional threaded rod 14. Each transmission block 15 is fixedly arranged with a corresponding L-clamp 12. By rotating the bidirectional threaded rod 14, the two transmission blocks 15 can be driven to move closer or farther away, thereby causing the two L-clamps 12 to move closer or farther away to clamp and release the mounting plate 3 of the sensor 1.

[0036] In order to facilitate the rotation and locking of the bidirectional threaded rod 14, in this embodiment, the front end of the bidirectional threaded rod 14 extends to the outside of the base plate 10 and is fixedly provided with a rotating portion 16, and a locking nut 17 is threadedly connected to the bidirectional threaded rod 14 located on the outside of the base plate 10; in a normal state, the locking nut 17 is in conflict with the base plate 10 to lock the bidirectional threaded rod 14 and prevent the bidirectional threaded rod 14 from rotating. When the bidirectional threaded rod 14 needs to be rotated, the locking nut 17 is screwed to make the locking nut 17 away from the base plate 10, and then the bidirectional threaded rod 14 can be conveniently rotated through the rotating portion 16.

[0037] In order to increase the stability of the rotation of the bidirectional threaded rod 14 , in this embodiment, a fixing plate 18 is rotatably connected to the junction of the two threads of the bidirectional threaded rod 14 , and the fixing plate 18 is fixed to the inner bottom wall of the transmission chamber 13 .

[0038] In order to achieve the purpose of locking the relative positions of the mounting sleeve 9 and the sliding sleeve 8, in this embodiment, a guide groove 19 is opened on the outer surface of the mounting sleeve 9 along the left and right directions, and a locking pin 20 is slidably arranged on the mounting sleeve 9 through the guide groove 19. The right side surface of the sliding sleeve 8 extends to the right to the right side of the mounting sleeve 9 and is coaxially fixed with a locking ring 21. A plurality of locking grooves 22 that are compatible with the locking pin 20 are evenly opened on the locking ring 21 along the circumference; the locking pin 20 slides to the right into the corresponding locking groove 22 to achieve the fixing of the relative positions of the mounting sleeve 9 and the sliding sleeve 8. When the mounting sleeve 9 needs to be rotated, the locking pin 20 is slid to the left so that the locking pin 20 is disengaged from the corresponding locking groove 22, and then the mounting sleeve 9 is rotated. The mounting sleeve 9 rotates 180 degrees, and the sensor 1 is driven to rotate 180 degrees through the sensor fixing device, and then the locking pin 20 is slid to the right into the corresponding locking groove 22 on the locking ring 21 to achieve the fixing of the relative positions of the mounting sleeve 9 and the sliding sleeve 8.

[0039] In order to prevent the locking pin 20 from accidentally disengaging from the locking groove 22, in this embodiment, a locking spring 23 is arranged in the guide groove 19, and the left end of the locking spring 23 is fixed to the inner wall of the locking groove 22, and the right end of the locking spring 23 is fixed to the left side surface of the locking pin 20. The locking spring 23 pushes the locking pin 20 to move to the right all the time to prevent the locking pin 20 from disengaging from the locking groove 22.

[0040] In order to achieve locking of the relative position of the sliding sleeve 8 and the test tube 6, in the present embodiment, a locking bolt 24 is threadedly connected between two adjacent locking grooves 22 on the locking ring 21, and the bottom end of the locking bolt 24 is in contact with the outer surface of the test tube 6; by screwing the locking bolt 24, the bottom end of the locking bolt 24 is moved radially toward the center of the test tube 6, so that the bottom end of the locking bolt 24 is in contact with the outer surface of the test tube 6, so that the relative position of the sliding sleeve 8 and the test tube 6 is locked. When the sliding sleeve 8 needs to be moved, the locking bolt 24 is screwed so that the bottom end of the locking bolt 24 is out of contact with the outer surface of the test tube 6, and the sliding sleeve 8 can be slid left and right to move.

[0041] To increase the stability of the left-right movement of the sliding sleeve 8, in this embodiment, a sliding rail 25 is fixedly provided on the test tube 6 along the left-right direction, and the two sliding sleeves 8 are slidably arranged with the test tube 6 left-right through the limiting grooves and the sliding rails 25 opened on the inner wall.

[0042] In this embodiment, the middle section of the test tube 6 is provided with a bracket 26 and a base of the fan 5 which are fixedly arranged with a base plate 27 below.

[0043] The working principle of the utility model is as follows: during the test, the mounting plates 3 of the two sensors 1 of the ultrasonic gas meter are respectively placed between the corresponding two L clamping plates 12, and then the bidirectional threaded rod 14 is rotated so that the bidirectional threaded rod 14 drives the two L clamping plates 12 to move close to each other through the transmission block 15, and the mounting plate 3 is clamped to fix the sensor 1. By rotating the mounting sleeve 9, the mounting sleeve 9 drives the sensor 1 to rotate through the bottom plate 10, the two L clamping plates 12 and the mounting plate 3 in turn, so that the two sensors 1 are located on the same side of the test tube 6, and the locking pin 20 is inserted into the corresponding locking groove 22, so that the relative position of the mounting sleeve 9 and the sliding sleeve 8 is fixed, and then the sliding sleeve 8 is moved to adjust the distance between the two sensors 1, so that the ultrasonic wave emitted by the transmitter 4 of the upstream sensor 1 enters the pipeline, passes through the fluid, and is reflected by the inner wall of the pipeline to the transmitter 4 of the downstream sensor 1, and the ultrasonic wave emitted by the transmitter 4 of the downstream sensor 1 can also be reflected to the transmitter 4 of the upstream sensor 1, and then the knob locking bolt 24 is turned so that the bottom end of the locking bolt 24 abuts against the outer surface of the test tube 6. Touch to fix the relative position of the sliding sleeve 8 and the test tube 6, then start the fan 5 to blow air into the test tube 6, and by comparing the time for the ultrasonic wave to be transmitted from the upstream sensor 1 to the downstream sensor 1 and the time for the ultrasonic wave to be transmitted from the downstream sensor 1 to the upstream sensor 1, the flow rate of the fluid in the pipeline can be calculated, and then the flow rate can be calculated in combination with the inner diameter of the pipeline, and output on the display screen on the operation box 2, and then compared with the flow rate tested by the flow test device 7, if the error is within the set range, it is qualified, and if the error exceeds the set range, it is unqualified; then by rotating the installation sleeve 9, the installation sleeve 9 drives the sensor 1 to rotate 180 degrees, at this time, the ultrasonic wave emitted by the transmitter 4 of one of the sensors 1 passes through the wall of the test tube 6, passes through the fluid, and then passes through the wall of the test tube 6 again to the transmitter 4 of the other sensor 1, and the transmitters 4 of the two sensors 1 compare the two-way transmission time, and the flow rate is calculated in combination with the known cross-sectional area of ​​the test tube 6, and compared with the flow rate tested by the flow test device 7, if the error is within the set range, it is qualified, and if the error exceeds the set range, it is unqualified; Fig.10 and Fig.11 The dotted line in the figure is the ultrasonic wave propagation path.

Claims

1. An ultrasonic gas meter pulsation flow detection device, characterized in that: The invention comprises a fan (5), and a test tube (6) fixedly arranged at the output end of the fan (5), a flow test device (7) being installed on the test tube (6), two sliding sleeves (8) being slidably arranged on the test tube (6) on the right side of the flow test device (7) in the left-right direction, the outer surface of the sliding sleeve (8) being rotatably connected to a mounting sleeve (9), the mounting sleeve (9) being provided with a sensor fixing device, the sensor fixing device being used to fix an ultrasonic sensor (1) so that the bottom end of the sensor (1) is in contact with the outer surface of the test tube (6).

2. The ultrasonic gas meter pulsation flow detection device according to claim 1, characterized in that: The sensor (1) fixing device comprises a base plate (10) fixedly arranged on the outer surface of the mounting sleeve (9), the upper end surface of the base plate (10) is provided with a slide groove (11) along the front-back direction, two L-shaped clamping plates (12) are slidably arranged in the slide groove (11), a transmission chamber (13) is provided on the inner bottom wall of the slide groove (11) along the front-back direction, and a driving device is arranged in the transmission chamber (13).

3. The ultrasonic gas meter pulsation flow detection device according to claim 2, characterized in that: The driving device comprises a bidirectional threaded rod (14) located in a transmission chamber (13) and rotatably connected to the base plate (10), wherein two threads of the bidirectional threaded rod (14) are respectively threadedly connected to transmission blocks (15), and each transmission block (15) is fixedly arranged on a corresponding L-shaped clamping plate (12).

4. The ultrasonic gas meter pulsation flow detection device according to claim 1, characterized in that: The outer surface of the installation sleeve (9) is provided with a guide groove (19) in the left-right direction, and the installation sleeve (9) is slidably provided with a locking pin (20) through the guide groove (19). The right side surface of the sliding sleeve (8) extends rightward to the right side of the installation sleeve (9) and is coaxially fixed with a locking ring (21). The locking ring (21) is evenly provided with a plurality of locking grooves (22) that match the locking pin (20) along the circumference.

5. The ultrasonic gas meter pulsation flow detection device according to claim 4, characterized in that: A plurality of locking bolts (24) are threadedly connected to the locking ring (21), and the bottom ends of the locking bolts (24) are in contact with the outer surface of the test tube (6).

6. The ultrasonic gas meter pulsation flow detection device according to claim 3, characterized in that: The front end of the bidirectional threaded rod (14) extends to the outside of the bottom plate (10) and is fixedly provided with a rotating portion (16), and a locking nut (17) is threadedly connected to the bidirectional threaded rod (14) located outside the bottom plate (10).

7. The ultrasonic gas meter pulsation flow detection device according to claim 6, characterized in that: A fixing plate (18) is rotatably connected to the joint of the two threads of the bidirectional threaded rod (14), and the fixing plate (18) is fixedly arranged on the inner bottom wall of the transmission chamber (13).

8. The ultrasonic gas meter pulsation flow detection device according to claim 4, characterized in that: A locking spring (23) is arranged in the guide groove (19), the left end of the locking spring (23) is fixedly arranged on the inner wall of the locking groove (22), and the right end of the locking spring (23) is fixedly arranged on the left side of the locking pin (20), and the locking spring (23) pushes the locking pin (20) to always move rightward.

9. The ultrasonic gas meter pulsation flow detection device according to claim 1, characterized in that: A slide rail (25) is fixedly arranged on the test tube (6) in the left-right direction, and the two sliding sleeves (8) are slidably arranged with the test tube (6) in the left-right direction through the limit grooves provided on the inner wall and the slide rail (25).

10. The ultrasonic gas meter pulsation flow detection device according to claim 1, characterized in that: A bracket (26) is provided in the middle section of the test tube (6), and the bracket (26) and the base of the fan (5) are fixedly arranged on a base plate (27) below.

Images