Tank truck, safety valve and airtightness test method for tank truck

Abstract

The present invention relates to a tank truck, a safety valve and an air tightness test method for the tank truck. The safety valve includes a valve body, a valve core and a limit assembly. A channel is provided in the valve body, and the channel is used to connect the inside and outside of the storage tank; the valve core is provided in the channel for opening and closing the channel; the limit assembly is detachably provided on the valve body, and the limit assembly extends into the channel and abuts against the valve core to prevent the valve core from opening the channel. The present invention utilizes the detachable structure of the limit assembly and the valve body to install the limit assembly on the valve body, and allows the limit assembly to extend into the channel and support the valve core to prevent the valve core from jumping. Therefore, in the air tightness test, even if the air tightness pressure in the storage tank is greater than the jumping pressure of the valve core, the valve core will not jump because it is supported by the limit assembly, which can effectively prevent the safety hazards caused by the safety valve jumping to discharge the medium, and enable the air tightness test of the storage tank to proceed smoothly; at the same time, after the air tightness test is completed, the limit assembly is disassembled to restore the normal opening and closing function of the valve core.

Description

Technical Field

[0001] The present invention relates to the technical field of storage tanks, and particularly to a tank truck, a safety valve and a method for airtightness testing of a tank truck. Background Art

[0002] The safety valve is an important safety component of a tank truck with a pump, and is used for overpressure protection of the storage tank on the tank truck to ensure the safety of storage and transportation of the storage tank. When the pressure in the storage tank is greater than the set opening pressure of the safety valve, the valve core in the safety valve will open, and the storage tank discharges pressure externally through the outlet of the safety valve. When the pressure in the storage tank is lower than the opening pressure, the safety valve closes again.

[0003] During the airtightness test of the storage tank of the tank truck, the opening pressure of the safety valve of the storage tank is usually less than the airtightness test pressure of the storage tank, that is, the design pressure. Therefore, during the airtightness test, due to the premature opening of the safety valve, it is easy to cause leakage of the medium in the storage tank, resulting in the inability to reach the design pressure of the airtightness test pressure of the storage tank on site, and further making the airtightness test unable to proceed smoothly. At the same time, the opening of the safety valve during the test will bring certain safety hazards and cause waste of resources. Summary of the Invention

[0004] An object of the present invention is to provide a safety valve, and an airtightness test structure is added to the existing safety valve to enable the airtightness test of the storage tank of the tank truck to proceed smoothly.

[0005] Another object of the present invention is to provide a tank truck, and an airtightness test structure is added to the safety valve of the existing tank truck to enable the airtightness test of the storage tank of the tank truck to proceed smoothly.

[0006] Still another object of the present invention is to provide a method for airtightness testing of a tank truck to enable the airtightness test of the storage tank of the tank truck to proceed smoothly, simplify the test process, and reduce the test cost.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] According to one aspect of the present invention, the present invention provides a safety valve, which includes: a valve body for being installed on the tank wall of the storage tank, having a channel therein, one end of the channel being used for communicating with the inside of the storage tank, and the other end being used for communicating with the outside of the storage tank; a valve core disposed in the channel of the valve body for opening and closing the channel; and a limiting component detachably disposed on the valve body, and at least part of the limiting component extends into the channel to abut against the valve core to prevent the valve core from opening the channel.

[0009] According to some embodiments of the present application, the limit assembly includes: a limit member, which is detachably provided on the valve body; and a push rod, one end of which is connected to the limit member, and the other end extends into the channel to abut against the valve core.

[0010] According to some embodiments of the present application, the push rod is adjustably disposed on the limit member, and the position of the push rod on the limit member can be adjusted along the extension direction of the channel to make the push rod approach or move away from the valve core.

[0011] According to some embodiments of the present application, the limiting member is provided with a threaded hole parallel to the extension direction of the channel; the push rod is provided with an external thread, and the push rod is threadedly connected to the threaded hole of the limiting member.

[0012] According to some embodiments of the present application, the limiting assembly further includes a locking nut, and the locking nut is threadedly sleeved on the push rod to lock the push rod on the limiting member.

[0013] According to some embodiments of the present application, the limiting member includes an integrally formed cover plate and a surrounding wall extending from the periphery of the cover plate; the cover plate is arranged in the channel; the outer peripheral wall of the surrounding wall is attached to the inner wall of the channel; a latching protrusion is protruding from the outer peripheral wall of the surrounding wall; a latching groove corresponding to the latching protrusion is provided on the inner wall of the channel, and the latching protrusion can be detachably latched in the latching groove; the push rod is connected to the cover plate.

[0014] According to some embodiments of the present application, a slide groove matching with the latching protrusion is recessed on the inner wall of the channel, and the latching groove is arranged at the bottom of the slide groove.

[0015] According to some embodiments of the present application, the latching protrusion is an elastic telescopic structure, and the latching protrusion can be elastically telescoped along the radial direction of the cover plate; the latching groove is formed by the bottom of the slide groove being recessed radially outward along the surrounding wall; the latching protrusion elastically abuts against the inside of the latching groove.

[0016] According to some embodiments of the present application, the latching protrusion is a fixed structure; the latching slot is formed by the bottom of the slide slot being recessed along the circumference of the surrounding wall toward one side of the slide slot; the latching protrusion is latched in the latching slot after rotating at the bottom of the slide slot.

[0017] According to some embodiments of the present application, a plurality of the latching protrusions are provided, and the plurality of the latching protrusions are circumferentially distributed on the outer peripheral wall of the surrounding wall.

[0018] According to some embodiments of the present application, the safety valve also includes a valve seat, which is used to be embedded in the tank wall of the storage tank, and the valve seat is provided with a threaded hole; the end of the valve body close to the outside of the storage tank is provided with an external thread, and is threadedly connected to the threaded hole of the valve seat.

[0019] According to another aspect of the present invention, the present invention provides a tanker truck, which includes a vehicle body, a storage tank provided on the vehicle body, and a safety valve provided on the storage tank, and the safety valve adopts the above-mentioned safety valve.

[0020] According to still another aspect of the present invention, the present invention provides a method for airtightness test of a tanker truck, and the method for airtightness test includes:

[0021] Install the limit component on the valve body so that the limit component extends into the channel of the valve body and abuts against the valve core;

[0022] Conduct an airtightness test on the storage tank;

[0023] After the airtightness test is completed, remove the limit component from the valve body to restore the opening and closing function of the valve core.

[0024] It can be seen from the above technical solutions that the embodiments of the present invention have at least the following advantages and positive effects:

[0025] The safety valve of the embodiment of the present invention can be applied to a tanker truck. When it is necessary to conduct an airtightness test on the storage tank of the tanker truck, by using the detachable structure cooperation between the limit component and the valve body, the limit component is installed on the valve body, and the limit component extends into the channel of the valve body to cooperate with the valve core and abut against the valve core to hold the valve core and prevent the valve core from popping up. Therefore, during the airtightness test, when the airtightness pressure in the storage tank is greater than the popping pressure of the valve core, the valve core will not pop up because it is held by the limit component, which can effectively prevent potential safety hazards caused by the discharge of the medium due to the popping of the safety valve and enable the smooth progress of the airtightness test of the storage tank; at the same time, after the airtightness test is completed, the limit component is removed, and the normal opening and closing function of the valve core can be restored. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of a tanker truck in an embodiment of the present invention.

[0027] Figure 2 is Figure 1 an enlarged structural schematic diagram of area A in

[0028] Figure 3 is Figure 2 a schematic structural diagram of the valve body and the valve core in

[0029] Figure 4 is Figure 2 a schematic structural diagram of the limit component installed on the valve body in

[0030] Figure 5 is Figure 4 a schematic structural diagram of the limit component in

[0031] Figure 6 is Figure 5Schematic structural diagram of the limiting component in the top view state.

[0032] Figure 7 is Figure 3 A schematic structural diagram of a part of the channel inside the valve body in [].

[0033] Figure 8 is Figure 3 Another schematic structural diagram of a part of the channel inside the valve body in [].

[0034] Explanation of the reference numerals is as follows:

[0035] 1, vehicle body; 2, storage tank; 3, safety valve; 31, valve body; 311, channel; 312, card slot; 313, sliding groove; 32, valve core; 33, spring; 34, limiting component; 341, limiting part; 3411, cover plate; 3412, surrounding wall; 3413, clamping protrusion; 342, ejector rod; 343, locking nut; 35, valve seat. Detailed implementation manners

[0036] Typical implementation manners reflecting the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different implementation manners, all of which do not depart from the scope of the present invention, and the descriptions and illustrations therein are essentially for illustrative purposes and not for limiting the present invention.

[0037] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0039] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0040] Please refer to Figure 1 and in combination with Figure 2 As shown, the tanker provided by the embodiment of the present invention can be applied to the transportation of liquefied gas. The tanker includes a vehicle body 1, a storage tank 2 provided on the vehicle body 1, and a safety valve 3 provided on the storage tank 2.

[0041] Please refer to Figure 2 , the safety valve 3 includes a valve body 31, a valve core 32, a spring 33, and a limiting component 34.

[0042] The valve body 31 is installed on the tank wall of the storage tank 2. A channel 311 is provided inside the valve body 31. One end of the channel 311 extends into the storage tank 2 along with one end of the valve body 31 and is in communication with the inside of the storage tank 2; the other end of the channel 311 extends out of or is exposed outside the storage tank 2 along with the other end of the valve body 31 to be in communication with the outside of the storage tank 2.

[0043] Please refer to Figure 2 , in some embodiments, the safety valve 3 may further include a valve seat 35. The valve seat 35 can be embedded in the tank wall of the storage tank 2, and a threaded hole is provided on the valve seat 35. One end of the valve body 31 close to the outside of the storage tank 2 is provided with an external thread and is threadedly connected to the threaded hole of the valve seat 35. The threaded connection and cooperation between the valve body 31 and the valve seat 35 can facilitate the installation of the valve body 31 on the storage tank 2 and at the same time facilitate the disassembly of the valve body 31 and the valve core 32 from the storage tank 2 for maintenance and replacement.

[0044] Please refer to Figure 3 and in combination with Figure 2 , the valve core 32 is movably provided in the channel 311 of the valve body 31 for opening and closing the channel 311. For example, the valve core 32 can form a sealing fit with the inner wall of the channel 311 to close the channel 311 inside the valve body 31.

[0045] Please refer to Figure 3 and in combination with Figure 4, a spring 33 is provided on the valve body 31, and one end of the spring 33 is connected to the valve core 32. The spring 33 is used to provide elastic force for the valve core 32 to drive the valve core 32 to close the channel 311 in the valve body 31. For example, when the storage tank 2 is filled with liquefied gas, the spring 33 can overcome a certain gas pressure to keep the valve core 32 in a state of closing the channel 311. Only when the gas pressure in the storage tank 2 is greater than a certain pressure threshold, the gas pressure will overcome the elastic force of the spring 33, forcing the valve core 32 to open the channel 311 in the valve body 31, so that the gas medium in the storage tank 2 is discharged to the outside of the storage tank 2 through the channel 311 of the valve body 31. The pressure threshold can be called the tripping pressure of the safety valve 3.

[0046] The channel 311 in the valve body 31 , the valve core 32 and the spring 33 cooperate to enable the storage tank 2 to have an overpressure protection function, which can effectively ensure the safety of storage and transportation of the storage tank 2 .

[0047] It should be noted that during the air tightness test of the tank 2 of the tank truck, the tripping pressure of the safety valve 3 of the tank 2 is usually lower than the air tightness test pressure of the tank 2, i.e., the design pressure. Therefore, during the air tightness test, the safety valve 3 trips too early, which may easily cause leakage of the medium in the tank 2, resulting in the on-site air tightness test pressure of the tank 2 failing to reach the design pressure, and thus preventing the air tightness test from being carried out smoothly.

[0048] See also Figure 4 Combined with Figure 2 The limiting assembly 34 is detachably disposed on the valve body 31 .

[0049] When it is necessary to conduct an air tightness test on the storage tank 2 of the tank truck, the limit assembly 34 can be installed on the valve body 31, and at least part of the limit assembly 34 will extend into the channel 311 and abut against the valve core 32, so that the valve core 32 remains in a closed state with the channel 311, thereby preventing the valve core 32 from opening the channel 311. The force exerted by the limit assembly 34 on the valve core 32 can be achieved through the connection structure between the limit assembly 34 and the valve body 31, and the force is greater than the difference between the design pressure of the air tightness test and the trip pressure of the valve core 32. That is, the limit assembly 34 can provide sufficient force for the valve core 32, so that when the design pressure is reached in the storage tank 2, the valve core 32 will not trip, thereby allowing the air tightness test of the storage tank 2 to be carried out smoothly.

[0050] When the air tightness test is completed, the limit assembly 34 is removed from the valve body 31 to restore the starting function (ie, the opening and closing function) of the valve core 32, thereby restoring the safety performance of the safety valve 3.

[0051] The detachable structure between the limit assembly 34 and the valve body 31 requires little structural change to the valve body 31 itself, is flexible and convenient to use, and is easy to operate, which is beneficial to improving the efficiency of the air tightness test and reducing the cost of the air tightness test.

[0052] Please refer to Figure 4 , in some embodiments, the limiting assembly 34 may include a limiting member 341 and a push rod 342. The limiting member 341 is detachably installed on the valve body 31. For example, the limiting member 341 is fixed to the end face of the valve body 31 near the outside of the storage tank 2 by bolts. One end of the push rod 342 is connected to the limiting member 341, and the other end of the push rod 342 extends into the channel 311 and abuts against the valve core 32.

[0053] Still referring to Figure 4 , in some embodiments, the push rod 342 is movably and adjustably arranged on the limiting member 341. The push rod 342 can adjust the position of the push rod 342 on the limiting member 341 along the extending direction of the channel 311, and further adjust the length of the part of the push rod 342 extending into the channel 311, so that the push rod 342 can approach or move away from the valve core 32. During use, the limiting member 341 can be first installed on the valve body 31, and then the push rod 342 is adjusted to gradually abut against the valve core 32 to ensure that the valve core 32 is pressed by the push rod 342 to prevent the valve core 32 from opening the channel 311. By using the adjustable fit between the push rod 342 and the limiting member 341 in the limiting assembly 34, it can be applied to valve cores 32 of different models. The push rod 342 can be a bolt and is threadedly connected to the limiting member 341 to achieve the adjustment function between the push rod 342 and the limiting member 341.

[0054] Please refer to Figure 4 and in combination with Figure 5 , in some embodiments, the limiting member 341 may include a cover plate 3411, a surrounding wall 3412 extending from the periphery of the cover plate 3411, and a clamping convex 3413 protruding from the outer peripheral wall of the surrounding wall 3412. The cover plate 3411 and the surrounding wall 3412 are integrally formed structures.

[0055] The cover plate 3411 is arranged in the channel 311. The cover plate 3411 can be distributed perpendicular to the channel 311 in the channel 311 and is located on the side of the valve core 32 close to the outside of the storage tank 2. The push rod 342 is connected to the cover plate 3411, and the push rod 342 can be arranged along the center line of the channel 311 at the center of the cover plate 3411.

[0056] Please refer to Figure 5 , in some embodiments, a threaded hole parallel to the extending direction of the channel 311 is formed in the cover plate 3411. For example, the threaded hole can be arranged along the center line of the channel 311 at the center of the cover plate 3411. The push rod 342 is provided with an external thread adapted to the threaded hole on the cover plate 3411, and the push rod 342 is threadedly connected to the threaded hole of the limiting member 341, and thus the position of the push rod 342 on the cover plate 3411 can be adjusted to make the push rod 342 extend into the channel 311 closer to or farther from the valve core 32.

[0057] In some embodiments, the limiting component 34 further includes a locking nut 343. The locking nut 343 is threadedly sleeved on the external thread of the ejector rod 342. When the locking nut 343 abuts against the cover plate 3411, the ejector rod 342 can be locked on the cover plate 3411. When the ejector rod 342 abuts against the valve core 32, the ejector rod 342 can be fixed in the channel 311 through the locking nut 343, ensuring that the ejector rod 342 stably abuts against the valve core 32 and preventing the valve core 32 from opening.

[0058] Please refer to Figure 4 and Figure 5 , the outer peripheral wall of the surrounding wall 3412 is attached to the inner wall of the channel 311, so that the cover plate 3411 can be inserted into the channel 311 along with the surrounding wall 3412.

[0059] The clamping protrusion 3413 protrudes from the outer peripheral wall of the surrounding wall 3412. A clamping groove 312 corresponding to the clamping protrusion 3413 is provided on the inner wall of the channel 311. By using the cooperation between the clamping protrusion 3413 of the surrounding wall 3412 and the clamping groove 312 on the inner wall of the channel 311, the cover plate 3411 and the ejector rod 342 can be detachably clamped in the channel 311 together with the surrounding wall 3412.

[0060] Please refer to Figure 6 , in some embodiments, multiple clamping protrusions 3413 can be provided on the outer peripheral wall of the surrounding wall 3412, and the multiple clamping protrusions 3413 are circumferentially and evenly distributed on the outer peripheral wall of the surrounding wall 3412. Correspondingly, multiple clamping grooves 312 are provided on the inner wall of the channel 311, and the clamping grooves 312 are in one-to-one alignment with the clamping protrusions 3413. The cooperation of the multiple clamping protrusions 3413 and the clamping grooves 312 can improve the firmness when the cover plate 3411 and the surrounding wall 3412 are installed in the channel 311, and further ensure the stability of the ejector rod 342 abutting against the valve core 32.

[0061] Please refer to Figure 7 and Figure 8 , in some embodiments, a sliding groove 313 corresponding to the clamping protrusion 3413 on the surrounding wall 3412 is recessed on the inner wall of the channel 311, and the clamping groove 312 is provided at the bottom of the sliding groove 313. When installing the limiting component 34, the cover plate 3411 and the surrounding wall 3412 can be pressed into the channel 311 through the alignment of the clamping protrusion 3413 and the sliding groove 313. When the clamping protrusion 3413 enters the clamping groove 312 along the sliding groove 313, the clamping protrusion 3413 is in alignment and clamped with the clamping groove 312, thereby fixing the limiting component 34 in the channel 311.

[0062] Please refer to Figure 7, in some embodiments, the clamping protrusion 3413 on the surrounding wall 3412 adopts an elastic telescopic structure. The clamping protrusion 3413 can elastically expand and contract in the radial direction of the cover plate 3411. In the natural state, the clamping protrusion 3413 protrudes from the outer peripheral wall surface of the surrounding wall 3412 under the action of elastic force. Under external pressure, the clamping protrusion 3413 partially or completely contracts into the inside of the surrounding wall 3412.

[0063] The clamping groove 312 on the inner wall of the channel 311 can be recessed radially outward from the bottom of the sliding groove 313 along the surrounding wall 3412. When the clamping protrusion 3413 slides along the sliding groove 313 to the clamping groove 312, the clamping protrusion 3413 can elastically abut against the inside of the clamping groove 312 under the action of elastic force, thereby fixing the cover plate 3411 and the surrounding wall 3412 in the channel 311.

[0064] Please refer to Figure 8 , in some embodiments, the clamping protrusion 3413 on the surrounding wall 3412 adopts a fixed structure, and the clamping protrusion 3413, the surrounding wall 3412 and the cover plate 3411 are integrally formed.

[0065] The clamping groove 312 on the inner wall of the channel 311 is recessed from the bottom of the sliding groove 313 along the circumferential direction of the surrounding wall 3412 to one side of the sliding groove 313. When the clamping protrusion 3413 slides along the sliding groove 313 to the clamping groove 312, the cover plate 3411 and the surrounding wall 3412 can be rotated so that the clamping protrusion 3413 rotates at the bottom of the sliding groove 313, and then is clamped in the clamping groove 312.

[0066] Based on the above structure of the tanker and the safety valve 3 on the tanker, the embodiment of the present invention also provides a method for airtightness test of a tanker. The airtightness test method includes the following steps:

[0067] Install the limiting component 34 on the valve body 31 so that the limiting component 34 extends into the channel 311 of the valve body 31 and abuts against the valve core 32 to prevent the valve core 32 from opening the channel 311.

[0068] Perform an airtightness test on the storage tank 2. Since the valve core 32 is abutted by the limiting component 34 and the valve core 32 is closed, that is, the valve core 32 loses the function of popping up, the airtightness test can be smoothly performed according to the design pressure.

[0069] After the airtightness test is completed, remove the limiting component 34 from the valve body 31 to restore the opening and closing function of the valve core 32, that is, restore the normal safety performance of the safety valve 3.

[0070] The above tank truck air tightness test method utilizes a detachable limiter assembly 34 added to the safety valve 3 to cooperate with the valve core 32. Before the test, the limiter assembly 34 is installed to limit the valve core 32, so that the air tightness test can be carried out smoothly. After the test, the limiter assembly 34 is removed to restore the safety function of the safety valve 3. It is flexible and convenient to use, simple to operate, and is conducive to improving the efficiency of the air tightness test. At the same time, the structural changes to the safety valve 3 itself are relatively small, which is conducive to reducing the production cost while improving the performance of the safety valve 3.

[0071] It can be seen from the above technical solutions that the embodiments of the present invention have at least the following advantages and positive effects:

[0072] The safety valve 3 of the embodiment of the present invention can be applied to a tank truck. When the storage tank 2 of the tank truck needs to be tested for air tightness, the limit assembly 34 is matched with the detachable structure of the valve body 31, the limit assembly 34 is installed on the valve body 31, and the limit assembly 34 is extended into the channel 311 of the valve body 31 to match with the valve core 32, to support the valve core 32, and to prevent the valve core 32 from jumping. Therefore, during the air tightness test, when the air tightness pressure in the storage tank 2 is greater than the jumping pressure of the valve core 32, the valve core 32 will not jump because it is supported by the limit assembly 34, which can effectively prevent the safety hazard caused by the discharge of the medium by the safety valve 3 jumping, and the air tightness test of the storage tank 2 can be carried out smoothly; at the same time, after the air tightness test is completed, the limit assembly 34 is disassembled to restore the normal opening and closing function of the valve core 32.

[0073] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A safety valve, characterized in that, it includes: a valve body for being installed on the tank wall of a storage tank, having a channel inside, one end of the channel is used to communicate with the inside of the storage tank, and the other end is used to communicate with the outside of the storage tank; a valve core disposed in the channel of the valve body for opening and closing the channel; a spring disposed outside the channel of the valve body, one end of the spring abuts against the valve body, and the other end abuts against the valve core, and the spring is used to drive the valve core to close the channel; a limit assembly detachably disposed on the valve body, and at least part of the limit assembly extends into the channel to abut against the valve core so as to close the channel by the valve core and prevent the valve core from opening the channel; the limit assembly includes: a limit member detachably disposed on the valve body; a push rod, one end of which is connected to the limit member, and the other end extends into the channel to abut against the valve core.

2. The safety valve according to claim 1, characterized in that, the push rod is adjustably disposed on the limit member and can adjust the position of the push rod on the limit member along the extending direction of the channel so that the push rod approaches or moves away from the valve core.

3. The safety valve according to claim 2, characterized in that, a threaded hole parallel to the extending direction of the channel is formed on the limit member; external threads are provided on the push rod, and the push rod is threadedly connected to the threaded hole of the limit member.

4. The safety valve according to claim 3, characterized in that, the limit assembly further includes a locking nut, and the locking nut is threadedly sleeved on the push rod to lock the push rod on the limit member.

5. The safety valve according to claim 1, characterized in that, the limit member includes an integrally formed cover plate and a surrounding wall extending from the periphery of the cover plate; the cover plate is disposed in the channel; the outer peripheral wall of the surrounding wall is attached to the inner wall of the channel; a clamping projection is prominently provided on the outer peripheral wall of the surrounding wall; a clamping groove corresponding to the clamping projection is provided on the inner wall of the channel, and the clamping projection is detachably clamped on the clamping groove; the push rod is connected to the cover plate.

6. The safety valve according to claim 5, characterized in that, a sliding groove matching with the clamping projection is recessed on the inner wall of the channel, and the clamping groove is disposed at the bottom of the sliding groove.

7. The safety valve according to claim 6, characterized in that, the clamping projection is an elastic telescopic structure, and the clamping projection can elastically expand and contract along the radial direction of the cover plate; the clamping groove is recessed outward along the radial direction of the surrounding wall from the bottom of the sliding groove; the clamping projection elastically abuts in the clamping groove.

8. The safety valve according to claim 6, characterized in that, the clamping projection is a fixed structure; the clamping groove is recessed from the bottom of the sliding groove along the circumferential direction of the surrounding wall to one side of the sliding groove; the clamping projection is rotated at the bottom of the sliding groove and then clamped in the clamping groove.

9. The safety valve according to claim 5, characterized in that, a plurality of clamping projections are provided, and the plurality of clamping projections are circumferentially distributed on the outer peripheral wall of the surrounding wall.

10. The safety valve according to claim 1, characterized in that, The safety valve further includes a valve seat for being embedded in the tank wall of the storage tank, and a threaded hole is provided on the valve seat; One end of the valve body close to the outside of the storage tank is provided with an external thread and is threadedly connected to the threaded hole of the valve seat.

11. A tanker truck, characterized in that, it includes a vehicle body, a storage tank provided on the vehicle body, and a safety valve provided on the storage tank, and the safety valve adopts the safety valve described in any one of claims 1-10.

12. A method for airtightness test of a tanker truck as claimed in claim 11, characterized in that, it includes: Installing a limiting component on the valve body so that the limiting component extends into the channel of the valve body to abut against the valve core; Performing an airtightness test on the storage tank; After the airtightness test is completed, the limiting component is removed from the valve body to restore the opening and closing function of the valve core.

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