Automobile differential pressure pipe air tightness test device

Abstract

The invention discloses an automobile differential pressure pipe air tightness test device, which includes a test bench, on which a first clamping mechanism and a second clamping mechanism are provided, a torque detection mechanism, which includes a driving motor connected to the test bench, the rotating shaft of the driving motor is coaxially connected to a closing component, the free end face of the closing component is provided with a concave closing cavity which is threadedly connected to the first end of the differential pressure pipe to be tested, and when the closing component rotates with the rotating shaft of the driving motor, the closing cavity is threadedly connected to the first end of the differential pressure pipe to be tested; a torque sensor, which is used to supply an air source for introducing air flow into the differential pressure pipe to be tested; and a pressure detection sensor, which is used to detect the pressure of the gas in the differential pressure pipe to be tested. The automobile differential pressure pipe air tightness test device can test the influence of the torque of the bolt at the installation end of the differential pressure pipe on the air tightness or leakage of the differential pressure pipe, and has a simple structure, convenient test operation, accurate test, strong versatility and good stability.

Description

Technical Field

[0001] The invention relates to the technical field of automobile component testing, in particular to an automobile differential pressure pipe air tightness testing device. Background Art

[0002] The automobile exhaust system is a system that collects and discharges exhaust gas. It is generally composed of an exhaust manifold, an exhaust pipe, a post-processor, a pressure difference sensor, and an exhaust tail pipe. It mainly plays the role of reducing the exhaust gas discharged by the engine and reducing the engine exhaust noise. With increasingly stringent emission regulations, light gasoline vehicles are generally designed with a particulate filter to control the size and number of particulate matter in the engine exhaust. The automobile's pressure difference pipe is connected to the air inlet and outlet of the particulate filter, and is respectively connected to the pressure difference sensor to detect the pressure difference between the air inlet and outlet of the particulate filter to determine whether the particulate filter can work properly. Due to the limitations of the installation environment, automotive differential pressure tubes are generally bent with multiple corners, and a mounting plate is welded on the differential pressure tube. During the bending process, the inner wall of the tube is likely to shrink or the tube may become partially flattened, which may cause the differential pressure tube to rupture. In the process of welding the mounting plate, the high local temperature may cause the tube wall to expand and contract unevenly due to heat, resulting in shrinkage holes. In addition, the mounting end of the differential pressure tube is generally threaded. At what torque can the threaded connection be used to ensure the airtightness technical requirements of the differential pressure tube or keep the leakage of the differential pressure tube within the set range? Since automobile differential pressure pipe parts have very high requirements for air tightness, the test of the air tightness performance of automobile differential pressure pipes is a necessary test item in the production of automobile differential pressure pipes, which can effectively check the quality of automobile differential pressure pipes and determine the qualified rate of products; and currently, the air tightness of pipe fittings is tested by passing gas, and the test process and items are relatively simple, and it is impossible to test the influence of the torque of the bolts at the installation end of the differential pressure pipe on the air tightness or leakage of the differential pressure pipe. Therefore, the air tightness test device of the pipe fitting in the prior art cannot meet the needs of the air tightness performance test of automobile differential pressure pipes. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide an automobile pressure differential pipe air tightness test device which can not only perform air tightness test on the pipe body of the automobile pressure differential pipe, but also test the influence of the torque of the bolts at the installation end of the pressure differential pipe on the air tightness or leakage of the pressure differential pipe, and has a simple structure, convenient test operation, accurate test, strong versatility and good stability.

[0004] The technical solution of the present invention is to provide an automobile differential pressure pipe air tightness test device having the following structure:

[0005] A test bench, on which a first clamping mechanism and a second clamping mechanism are provided, wherein the first clamping mechanism is used to clamp the first end of the pressure differential tube to be tested, the outer side wall of the first end of the pressure differential tube to be tested having a connected external thread, and the second clamping mechanism is used to clamp the second end of the pressure differential tube to be tested;

[0006] The torque detection mechanism comprises a driving motor connected to the test bench, wherein the rotating shaft of the driving motor is coaxially connected to a sealing component, and a sealing cavity which is concave and threadedly connected to the first end of the pressure differential tube to be tested is provided on the free end surface of the sealing component, and when the sealing component rotates with the rotating shaft of the driving motor, the sealing cavity is threadedly connected to the first end of the pressure differential tube to be tested;

[0007] A torque sensor is used to detect the torque when the drive motor shaft rotates;

[0008] An air source, the air outlet of which is connected to the second end of the pressure differential tube to be tested through a pipeline, and is used to introduce air into the pressure differential tube to be tested;

[0009] The pressure detection sensor is connected to the pipeline between the gas outlet of the gas source and the pressure differential pipe to be tested, and is used to detect the pressure of the gas in the pressure differential pipe to be tested;

[0010] The control box is electrically connected to the torque sensor and the pressure detection sensor, and is used to display the torque data change detected by the torque sensor and the pressure change of the gas in the pressure differential tube detected by the pressure detection sensor.

[0011] Preferably, the sealing component comprises a hollow outer shell which is coaxially arranged with the rotating shaft of the driving motor, a sealing head is movably connected in the inner hole of the outer shell, the sealing cavity is arranged on the outer end surface of the sealing head, and the inner circumferential wall of the sealing cavity is provided with an internal thread which is threadedly connected with the external thread on the outer side wall of the first end of the pressure differential tube to be tested; an elastic member is provided in the inner hole of the outer shell, one end of the elastic member is connected to the tail end of the sealing head, and the other end of the elastic member is connected to the end cover connected to the tail end of the outer shell.

[0012] Preferably, the tail end of the closing head is connected to a positioning plate, the outer circumferential wall of the positioning plate is gap-matched with the inner hole of the shell, and the tail end of the positioning plate is connected to a positioning column for the elastic member to be sleeved.

[0013] Preferably, a plug protruding into the closed cavity is provided at the center of the inner bottom wall of the closed cavity, and the outer circumferential wall of the plug is a cone with a small outside and a large inside. When the internal thread of the closed cavity is threadedly connected to the external thread of the first end of the pressure differential tube to be tested, the plug extends into the inner hole of the first end of the pressure differential tube to be tested, and the outer wall of the plug fits with the inner wall of the inner hole of the first end of the pressure differential tube to be tested.

[0014] Preferably, the first clamping mechanism includes a first clamping cylinder and a first positioning seat installed on the test bench, the first positioning seat is provided with a first positioning groove for placing the first end of the pressure differential tube to be tested, the free end of the piston rod of the first clamping cylinder is connected to a first pressure rod, and the first pressure rod clamps the pressure differential tube to be tested in the first positioning groove under the drive of the piston rod of the first clamping cylinder.

[0015] Preferably, the second clamping mechanism includes a second clamping cylinder, a third clamping cylinder and a second positioning seat installed on the test bench, the second positioning seat is provided with a second positioning groove for placing the second end of the pressure differential tube to be tested, the free end of the piston rod of the second clamping cylinder is connected to a second pressure rod, and the second pressure rod clamps the pressure differential tube to be tested in the second positioning groove under the drive of the piston rod of the second clamping cylinder; the free end of the piston rod of the third clamping cylinder is connected to an air nozzle, and the air nozzle is provided with an air inlet and an air outlet, the air inlet is connected to the air source through a pipeline, and the air outlet is connected to the second end of the pressure differential tube to be tested under the action of the piston rod of the third clamping cylinder.

[0016] Preferably, the torque sensor is connected to a transmission shaft, one end of the transmission shaft is transmission-connected to a rotating shaft of a driving motor via a reducer, and the other end of the transmission shaft is connected to a closed component.

[0017] Preferably, a support plate is connected to the test bench, the second clamping mechanism is detachably connected to the support plate, and the second clamping mechanism can adjust its position in the length direction of the support plate to adjust the distance of the second clamping mechanism relative to the first clamping mechanism.

[0018] Preferably, the support plate is provided with two vertically arranged limit plates, and an installation space for installing a second positioning seat is provided between the two limit plates, and the second positioning seat is slidably fitted in the installation space; an adjusting screw is threadedly connected to the two limit plates, and the free ends of the two adjusting screws are respectively abutted against the two side walls of the second positioning seat, so as to adjust the position of the second positioning seat in the installation space; the second clamping cylinder and the third clamping cylinder are both connected to the second positioning seat.

[0019] Preferably, the test bench is slidably matched with a sliding seat, the test bench is connected to a driving motor that drives the sliding seat to slide, and the torque detection mechanism is connected to the sliding seat and moves synchronously with the sliding seat.

[0020] After adopting the above structure, the automobile differential pressure tube air tightness testing device of the present invention has the following advantages compared with the prior art: when the automobile differential pressure tube air tightness testing device is in use, the two ends of the differential pressure tube to be tested are first clamped on the first clamping mechanism and the second clamping mechanism respectively, and then the driving motor is started, and the driving motor drives the closing component to rotate, so that the closing cavity is threadedly connected with the first end of the differential pressure tube to be tested, and the torque sensor detects the torque when the driving motor shaft rotates, that is, detects the torque when the closing cavity is threadedly connected with the first end of the differential pressure tube to be tested and transmits the torque data to the control box; the air source provides air flow and passes it into the differential pressure tube to be tested, and the pressure detection sensor monitors the pressure change of the gas in the differential pressure tube to be tested in real time and transmits the data of the gas pressure change to the control box; when the pressure of the gas passed into the differential pressure tube to be tested is below the set air pressure value, the air source is stopped from supplying air. , after a certain period of time, according to the change of the air pressure value of the pressure detection sensor, it is determined whether the air tightness of the pressure differential tube to be tested meets the requirements, so as to complete the detection of the air tightness of the pressure differential tube to be tested; the air source can provide different air pressures for testing, and according to the different air pressures introduced into the pressure differential tube to be tested, the closed chamber is controlled by the control box to adjust the torque of the threaded connection between the first ends of the pressure differential tube to be tested, so as to test the influence of the torque when the first end of the pressure differential tube to be tested is threadedly connected on the air tightness of the pressure differential tube to be tested; therefore, the automobile pressure differential tube air tightness test device can not only perform air tightness test on the automobile pressure differential tube body, but also can test the influence of the bolt torque on the air tightness or leakage of the pressure differential tube when the installation end of the pressure differential tube is installed; the automobile pressure differential tube air tightness test device has a simple structure, convenient test operation, accurate test, strong versatility and good stability. Secondly, the arrangement of the closing head and the elastic member in the closing assembly makes the closing head active, so that the threaded connection between the closing chamber and the first end of the pressure differential tube to be tested is more firm and stable during the rotation of the closing assembly with the driving motor shaft, thereby further improving the accuracy of the air tightness test of the pressure differential tube to be tested. Furthermore, the arrangement of the plug at the center of the inner bottom wall of the closing chamber, when the internal thread of the closing chamber is threadedly connected with the external thread of the first end of the pressure differential tube to be tested, the plug extends into the inner hole of the first end of the pressure differential tube to be tested, and the outer side wall of the plug fits the inner wall of the inner hole of the first end of the pressure differential tube to be tested, so as to further improve the accuracy of the air tightness test of the pressure differential tube to be tested, so that the control box can accurately calculate the influence of the threaded connection torque size on the air tightness or leakage of the pressure differential tube when the first end of the pressure differential tube is installed. In addition, the second clamping mechanism can adjust the installation position on the support plate, so as to adjust the distance of the second clamping mechanism relative to the first clamping mechanism, so that the automobile pressure differential tube air tightness test device can be suitable for testing the air tightness of automobile pressure differential tubes of different lengths, and its versatility is good. In addition, the torque detection mechanism can slide on the test bench to adjust the position, so that the automobile differential pressure pipe air tightness testing device can be suitable for testing the air tightness of automobile differential pressure pipes of different lengths and sizes, and has better versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an automobile differential pressure pipe air tightness testing device of the present invention.

[0022] Figure 2 It is a side structural schematic diagram of the air tightness testing device for automobile differential pressure pipe of the present invention.

[0023] Figure 3 The invention is a schematic cross-sectional structural diagram of a sealing component of a device for testing air tightness of a differential pressure pipe for automobiles.

[0024] Figure 4 It is a structural schematic diagram of another angle of the automobile differential pressure pipe air tightness testing device of the present invention.

[0025] As shown in the figure:

[0026] 1. Test bench, 100, slide rail, 101, slide seat, 102, push motor, 2. First clamping mechanism, 200, first clamping cylinder, 201, first positioning seat, 202, first positioning groove, 203, first pressure rod, 3. Second clamping mechanism, 300, second clamping cylinder, 301, third clamping cylinder, 302, second positioning seat, 303, second positioning groove, 304, second pressure rod, 305, air nozzle, 306, air inlet, 3 07. Air outlet, 4. Support plate, 400. Limit plate, 401. Installation space, 402. Adjusting screw, 5. Driving motor, 500. Reducer, 501. Transmission shaft, 6. Torque sensor, 7. Closing assembly, 700. Housing, 701. Closing head, 702. Closing cavity, 703. Internal thread, 704. Plug, 705. Positioning plate, 706. Positioning column, 707. Elastic part, 708. End cover, 8. Pressure differential tube to be tested. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] See also Figure 1 to Figure 4 As shown;

[0029] The present invention discloses an air tightness testing device for automobile differential pressure tubes, which comprises a test bench 1, on which a first clamping mechanism 2 and a second clamping mechanism 3 are provided, wherein the first clamping mechanism 2 is used to clamp the first end of a differential pressure tube 8 to be tested, and the outer side wall of the first end of the differential pressure tube 8 to be tested has a connected external thread, and the second clamping mechanism 3 is used to clamp the second end of the differential pressure tube 8 to be tested; the first clamping mechanism 2 comprises a first clamping cylinder 200 and a first positioning seat 201 installed on the test bench 1, the first positioning seat 201 is provided with a first positioning groove 202 for placing the first end of the differential pressure tube 8 to be tested, the free end of the piston rod of the first clamping cylinder 200 is connected to a first pressing rod 203, and the first pressing rod 203 presses the differential pressure tube 8 to be tested in the first positioning groove 202 under the drive of the piston rod of the first clamping cylinder 200. The second clamping mechanism 3 includes a second clamping cylinder 300, a third clamping cylinder 301 and a second positioning seat 302 installed on the test bench 1. The second positioning seat 302 is provided with a second positioning groove 303 for placing the second end of the pressure differential tube 8 to be tested. The free end of the piston rod of the second clamping cylinder 300 is connected to a second pressing rod 304. The second pressing rod 304 presses the pressure differential tube 8 to be tested in the second positioning groove 303 under the drive of the piston rod of the second clamping cylinder 300; the free end of the piston rod of the third clamping cylinder 301 is connected to an air nozzle 305, and the air nozzle 305 is provided with an air inlet 306 and an air outlet 307. The air inlet 306 is connected to the air source through a pipeline, and the air outlet 307 is connected to the second end of the pressure differential tube 8 to be tested under the action of the piston rod of the third clamping cylinder 301.

[0030] The torque detection mechanism includes a driving motor 5 connected to the test bench 1, the rotating shaft of the driving motor 5 is coaxially connected to a closing component 7, the free end face of the closing component 7 is provided with a concave closing cavity 702 which is threadedly connected to the first end of the pressure differential tube 8 to be tested, when the closing component 7 rotates with the rotating shaft of the driving motor 5, the closing cavity 702 is threadedly connected to the first end of the pressure differential tube 8 to be tested; the torque sensor 6 is connected to the transmission shaft 501, one end of the transmission shaft 501 is connected to the rotating shaft of the driving motor 5 through a reducer 500, and the other end of the transmission shaft 501 is connected to the closing component 7. A torque sensor 6 is used to detect the torque when the shaft of the driving motor 5 rotates; an air source, the air outlet end of which is connected to the second end of the pressure differential tube 8 to be tested through a pipeline, and is used to introduce air flow into the pressure differential tube 8 to be tested; a pressure detection sensor is connected to the pipeline between the air outlet end of the air source and the pressure differential tube 8 to be tested, and is used to detect the pressure of the gas in the pressure differential tube 8 to be tested; a control box is electrically connected to the torque sensor and the pressure detection sensor, and is used to display the torque data changes detected by the torque sensor and the pressure changes of the gas in the pressure differential tube detected by the pressure detection sensor.

[0031] When the automobile differential pressure pipe air tightness test device is in use, the two ends of the differential pressure pipe 8 to be tested are first clamped on the first clamping mechanism 2 and the second clamping mechanism 3 respectively, and then the driving motor 5 is started, and the driving motor 5 drives the sealing component 7 to rotate, so that the sealing cavity 702 is threadedly connected with the first end of the differential pressure pipe 8 to be tested, and the torque sensor 6 detects the torque when the rotating shaft of the driving motor 5 rotates, that is, detects the torque when the sealing cavity 702 is threadedly connected with the first end of the differential pressure pipe 8 to be tested and transmits the torque data to the control box; the air source provides air flow and passes it into the differential pressure pipe 8 to be tested, and the pressure detection sensor monitors the pressure change of the gas in the differential pressure pipe to be tested in real time and transmits the data of the gas pressure change to the control box; when the pressure of the gas passed into the differential pressure pipe to be tested is within the set air pressure value Under the condition that the air supply of the air source is stopped, after a period of time, the air tightness of the pressure differential tube to be tested is determined according to the change of the air pressure value of the pressure detection sensor, thereby completing the detection of the air tightness of the pressure differential tube to be tested; the air source can provide different sizes of air pressure for testing, and according to the different air pressures introduced into the pressure differential tube to be tested, the closed chamber is controlled by the control box to adjust the torque of the threaded connection between the first ends of the pressure differential tube to be tested, so as to test the influence of the torque size when the first end of the pressure differential tube to be tested is threadedly connected on the air tightness of the pressure differential tube to be tested; therefore, the automobile pressure differential tube air tightness test device can not only perform air tightness test on the automobile pressure differential tube body, but also can test the influence of the bolt torque size on the air tightness or leakage of the pressure differential tube when the mounting end of the pressure differential tube is installed.

[0032] See again Figure 1 and Figure 3 As shown, as an embodiment of the present invention; the sealing component 7 comprises a hollow shell 700 coaxially arranged with the rotating shaft of the driving motor 5, a sealing head 701 movably connected in the inner hole of the shell 700, the sealing cavity 702 is arranged on the outer end surface of the sealing head 701, and the inner circumferential wall of the sealing cavity 702 is provided with an internal thread 703 threadedly connected with the external thread on the outer wall of the first end of the pressure differential tube 8 to be tested; an elastic member 707 is arranged in the inner hole of the shell 700, one end of the elastic member 707 is connected to the tail end of the sealing head 701, and the other end of the elastic member 707 is connected to the end cover 708 connected to the tail end of the shell 700. The tail end of the sealing head 701 is connected to a positioning plate 705, the outer circumferential wall of the positioning plate 705 is in gap with the inner hole of the shell 700, and the tail end of the positioning plate 705 is connected to a positioning column 706 for the elastic member 707 to be sleeved. The automobile differential pressure pipe air tightness test device has a simple structure, convenient test operation, accurate test, strong versatility and good stability. Secondly, the arrangement of the closing head and the elastic member in the closing component makes the closing head active, and the threaded connection between the closing cavity and the first end of the differential pressure pipe to be tested is more firm and stable during the rotation of the closing component with the driving motor shaft, thereby further improving the accuracy of the air tightness test of the differential pressure pipe to be tested.

[0033] See again Figure 3 As shown, as an embodiment of the present invention, a plug 704 protruding into the closed cavity 702 is provided at the center of the inner bottom wall of the closed cavity 702, and the outer circumferential wall of the plug 704 is a conical shape with a small outer side and a large inner side. When the inner thread of the closed cavity 702 is threadedly connected with the outer thread of the first end of the pressure differential tube 8 to be tested, the plug 704 extends into the inner hole of the first end of the pressure differential tube 8 to be tested, and the outer side wall of the plug 704 fits with the inner wall of the inner hole of the first end of the pressure differential tube 8 to be tested. The setting of the plug at the center of the inner bottom wall of the closed cavity, when the inner thread of the closed cavity is threadedly connected with the outer thread of the first end of the pressure differential tube to be tested, the plug extends into the inner hole of the first end of the pressure differential tube to be tested, and the outer side wall of the plug fits with the inner wall of the inner hole of the first end of the pressure differential tube to be tested, further improves the accuracy of the air tightness test of the pressure differential tube to be tested, so that the control box can accurately calculate the influence of the threaded connection torque on the air tightness or leakage of the pressure differential tube when the first end of the pressure differential tube is installed.

[0034] See again Figure 1 , Figure 2 and Figure 4 As shown, as an embodiment of the present invention; a support plate 4 is connected to the test bench 1, the second clamping mechanism 3 is detachably connected to the support plate 4, and the second clamping mechanism 3 can adjust the position in the length direction of the support plate 4 to adjust the distance of the second clamping mechanism 3 relative to the first clamping mechanism 2. Specifically, two vertically arranged limit plates 400 are provided on the support plate 4, and an installation space 401 for installing the second positioning seat 302 is provided between the two limit plates 400, and the second positioning seat 302 is slidably matched in the installation space 401; an adjusting screw 402 is threadedly connected to the two limit plates 400, and the free ends of the two adjusting screws 402 are respectively against the two side walls of the second positioning seat 302, which are used to adjust the position of the second positioning seat 302 in the installation space 401; the second clamping cylinder 300 and the third clamping cylinder 301 are both connected to the second positioning seat 302. The test bench 1 is slidably matched with a sliding seat 101, and the sliding seat 101 is slidably matched with the slide rail 100. The test bench 1 is connected with a driving motor 102 for driving the sliding seat 101 to slide. The slide rail 100 is connected with a lead screw, and the lead screw is threadedly connected with the threaded hole on the sliding seat 101. The driving motor 102 drives the lead screw to rotate, so that the sliding seat 101 moves along the length direction of the slide rail 100; the torque detection mechanism is connected to the sliding seat 101 and moves synchronously with the sliding seat 101. The second clamping mechanism can adjust the installation position on the support plate to adjust the distance of the second clamping mechanism relative to the first clamping mechanism, and the torque detection mechanism can slide on the test bench to adjust the position, so that the automobile differential pressure pipe air tightness test device can be suitable for testing the air tightness of automobile differential pressure pipes of different lengths, and its versatility is good.

[0035] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An automobile differential pressure pipe air tightness test device, characterized in that: include A test bench, on which a first clamping mechanism and a second clamping mechanism are provided, wherein the first clamping mechanism is used to clamp the first end of the pressure differential tube to be tested, the outer side wall of the first end of the pressure differential tube to be tested having a connected external thread, and the second clamping mechanism is used to clamp the second end of the pressure differential tube to be tested; The torque detection mechanism comprises a driving motor connected to the test bench, wherein the rotating shaft of the driving motor is coaxially connected to a sealing component, and a sealing cavity which is concave and threadedly connected to the first end of the pressure differential tube to be tested is provided on the free end surface of the sealing component, and when the sealing component rotates with the rotating shaft of the driving motor, the sealing cavity is threadedly connected to the first end of the pressure differential tube to be tested; A torque sensor is used to detect the torque when the shaft of the driving motor rotates; the torque sensor is connected to the transmission shaft, one end of the transmission shaft is connected to the shaft of the driving motor through a reducer, and the other end of the transmission shaft is connected to the closed component; An air source, the air outlet of which is connected to the second end of the pressure differential tube to be tested through a pipeline, and is used to introduce air into the pressure differential tube to be tested; The pressure detection sensor is connected to the pipeline between the gas outlet of the gas source and the pressure differential pipe to be tested, and is used to detect the pressure of the gas in the pressure differential pipe to be tested; A control box, electrically connected to the torque sensor and the pressure detection sensor, for displaying the torque data change detected by the torque sensor and the pressure change of the gas in the pressure differential tube detected by the pressure detection sensor; The test bench is slidably matched with a sliding seat, and a driving motor for driving the sliding seat to slide is connected to the test bench. The torque detection mechanism is connected to the sliding seat and moves synchronously with the sliding seat.

2. The automobile differential pressure pipe air tightness testing device according to claim 1, characterized in that: The sealing component includes a hollow shell which is coaxially arranged with the driving motor shaft, a sealing head is movably connected in the inner hole of the shell, the sealing cavity is arranged on the outer end surface of the sealing head, and the inner circumferential wall of the sealing cavity is provided with an internal thread which is threadedly connected with the external thread on the outer side wall of the first end of the pressure differential tube to be tested; an elastic member is provided in the inner hole of the shell, one end of the elastic member is connected to the rear end of the sealing head, and the other end of the elastic member is connected to the end cover connected to the rear end of the shell.

3. The air tightness testing device for automobile differential pressure pipe according to claim 2, characterized in that: The tail end of the closing head is connected to a positioning plate, the outer circumferential wall of the positioning plate is gap-matched with the inner hole of the shell, and the tail end of the positioning plate is connected to a positioning column for the elastic member to be sleeved.

4. The air tightness testing device for automobile differential pressure pipe according to claim 2, characterized in that: A plug protruding into the closed cavity is provided at the center of the inner bottom wall of the closed cavity. The outer circumferential wall of the plug is a cone with a small outside and a large inside. When the internal thread of the closed cavity is threadedly connected with the external thread of the first end of the pressure differential tube to be tested, the plug extends into the inner hole of the first end of the pressure differential tube to be tested, and the outer wall of the plug fits with the inner wall of the inner hole of the first end of the pressure differential tube to be tested.

5. The air tightness testing device for automobile differential pressure pipe according to claim 1, characterized in that: The first clamping mechanism includes a first clamping cylinder and a first positioning seat installed on the test bench. The first positioning seat is provided with a first positioning groove for placing the first end of the pressure differential tube to be tested. The free end of the piston rod of the first clamping cylinder is connected to a first pressure rod. The first pressure rod clamps the pressure differential tube to be tested in the first positioning groove under the drive of the piston rod of the first clamping cylinder.

6. The air tightness testing device for automobile differential pressure pipe according to claim 5, characterized in that: The second clamping mechanism includes a second clamping cylinder, a third clamping cylinder and a second positioning seat installed on the test bench, the second positioning seat is provided with a second positioning groove for placing the second end of the pressure differential tube to be tested, the free end of the piston rod of the second clamping cylinder is connected with a second pressure rod, and the second pressure rod clamps the pressure differential tube to be tested in the second positioning groove under the drive of the piston rod of the second clamping cylinder; the free end of the piston rod of the third clamping cylinder is connected to an air nozzle, and the air nozzle is provided with an air inlet and an air outlet, the air inlet is connected to the air source through a pipeline, and the air outlet is connected to the second end of the pressure differential tube to be tested under the action of the piston rod of the third clamping cylinder.

7. The air tightness testing device for automobile differential pressure pipe according to claim 6, characterized in that: A support plate is connected to the test bench, and the second clamping mechanism is detachably connected to the support plate. The second clamping mechanism can adjust its position in the length direction of the support plate to adjust the distance of the second clamping mechanism relative to the first clamping mechanism.

8. The air tightness testing device for automobile differential pressure pipe according to claim 7, characterized in that: Two vertically arranged limit plates are provided on the support plate, and an installation space for installing a second positioning seat is provided between the two limit plates, and the second positioning seat is slidably fitted in the installation space; an adjusting screw is threadedly connected to the two limit plates, and the free ends of the two adjusting screws are respectively abutted against the two side walls of the second positioning seat, so as to adjust the position of the second positioning seat in the installation space; the second clamping cylinder and the third clamping cylinder are both connected to the second positioning seat.

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