Safety valve with set pressure switching device capable of being quickly assembled and switching method

Abstract

The invention discloses a safety valve with a set pressure switching device capable of being rapidly assembled and a switching method, and relates to the field of safety valves needing to rapidly switch set pressure, the safety valve comprises a pilot valve with a switching function and at least one set pressure switching device, and the set pressure switching device is connected to the pilot valve with the switching function. And each set pressure switching device is used for applying preset pressure to the basic valve rod, so that the set pressure of the safety valve obtained after the set pressure switching devices are installed on the pilot valve with the switching function is adjusted. The device can realize quick switching of the set pressure, is convenient to operate, does not need professional equipment, and expands the application range of the safety valve.

Description

Technical Field

[0001] The patent of the present invention relates to a set pressure switching device and a safety valve that can be assembled quickly, and belongs to the field of safety valves that require rapid switching of the set pressure. Background Art

[0002] As a safety accessory for pressure-bearing equipment, the safety valve is known as the last line of defense for overpressure protection and plays a particularly important role in ensuring the safe operation of process industries. Its function is to open the safety valve when the pressure in the equipment rises abnormally and reaches the set pressure, release a certain amount of medium to prevent the protected equipment from being damaged due to overpressure, and close it when the pressure in the equipment returns to normal to prevent the medium from continuing to flow out to ensure the normal operation of the system. When the working conditions at the project site change, the set pressure of the safety valve needs to be adjusted. Traditional safety valves need to turn the adjustment screw to change the compression of the spring to adjust the set pressure. And during the adjustment process, it is necessary to conduct multiple tests on the constant pressure platform to gradually adjust to the required set pressure. The entire adjustment process has requirements for equipment, site, and personnel, and the operation is cumbersome and time-consuming.

[0003] In some special industrial occasions, such as ships, there is no constant pressure equipment on site and the operating environment is relatively harsh. During ocean operations, the crew may not be able to accurately adjust the set pressure, and it is inconvenient for valve manufacturers to board the ship for debugging. In order to meet the needs of on-site working conditions, a device that can conveniently and quickly switch the set pressure is needed.

[0004] Through the analysis of scenarios such as ships that do not have the conditions for set pressure adjustment but have adjustment needs, it can be seen that the existing safety valves cannot meet their needs. Summary of the invention

[0005] The technical problem solved by the present application is to overcome the deficiencies of the prior art and provide a safety valve with a set pressure switching device that can be quickly assembled. The device can achieve rapid switching of the set pressure, is easy to operate, does not require professional equipment, and expands the application scope of the safety valve.

[0006] The present invention designs a set pressure switching device that can be quickly assembled and is suitable for various types of spring-loaded safety valves and pilot-operated safety valves. The switching device and the pilot valve of the spring-loaded safety valve or the pilot-operated safety valve can be quickly assembled and disassembled to realize the switching function of the set pressure. The present invention solves the problem of adjusting the set pressure of the safety valve at the engineering site, improves the ease of use of the safety valve, and expands its scope of application. Taking a pilot-operated safety valve as an example, the present invention innovatively develops a pilot valve that is compatible with the switching device and introduces the switching device.

[0007] The technical solutions provided by this application are as follows:

[0008] A safety valve with a set pressure switching device that can be quickly assembled comprises a pilot valve with a switching function and at least one set pressure switching device, wherein the set pressure switching device is connected to the pilot valve with a switching function, and each set pressure switching device is used to apply a preset pressure to a basic valve stem so that the set pressure of the safety valve obtained after the pilot valve with a switching function is installed with the set pressure switching device is adjusted.

[0009] The pilot valve with switching function also includes a valve body, a basic valve cover, a basic spring, a basic spring seat, a hollow adjusting screw and a basic valve cap; the basic valve cover is connected to the valve body, the hollow adjusting screw is threadedly connected to the basic valve cover and one end extends into the basic valve cover, the basic valve cap is threadedly connected to the outside of the basic valve cover, and the basic valve cap is sleeved on the outside of the hollow adjusting screw, and the end of the basic valve cap has an external thread for connecting a set pressure switching device; the basic spring seat is connected to the end of the hollow adjusting screw extending into the basic valve cover; the basic valve stem is located on the side of the basic spring seat away from the hollow adjusting screw, the basic spring is located between the basic valve stem and the basic spring seat, the other end of the basic valve stem is connected to the valve disc, and the valve disc cooperates with the valve seat of the valve body to form a seal; through holes are processed in the middle of the basic spring seat and the hollow adjusting screw, so that the structure of the set pressure switching device can penetrate from the through hole, thereby applying the pressure applied by the set pressure switching device to the basic valve stem, and then to the valve disc.

[0010] A support seat is provided at one end of the basic valve stem facing the hollow adjusting screw, and the structure of the set pressure switching device can penetrate through the through hole and contact with the support seat, so that the pressure applied by the set pressure switching device acts on the valve disc through the support seat.

[0011] When the pilot valve with the switching function is not connected to the set pressure switching device, the external thread of the end of the basic valve bonnet is threadedly connected with the basic sleeve, and the basic sleeve blocks the end of the basic valve bonnet.

[0012] The basic sleeve is provided with an opening at a position directly opposite to the end of the basic valve cap, and a basic screw plug is threadedly connected to the opening of the basic sleeve.

[0013] The set pressure switching device comprises a valve stem, a housing, a lower spring seat, a spring, an upper spring seat, an adjusting screw, a valve cover and a valve bonnet; the housing and the valve cover are fixedly and sealedly connected; the bottom of the housing away from the valve cover is provided with a through hole, the lower spring seat and the upper spring seat are located in the housing and the valve cover, and the spring is located between the lower spring seat and the upper spring seat; the adjusting screw is threadedly connected to an end of the valve cover away from the housing, and one end of the adjusting screw extends into the valve cover and contacts the upper spring seat; the valve stem is fixedly connected to the lower spring seat and passes through the lower spring seat in a direction away from the upper spring seat; the valve bonnet is threadedly connected to an end of the valve cover away from the housing, and the valve bonnet is sleeved on the outside of the adjusting screw, and an external thread is arranged on the outside of the end of the valve bonnet away from the valve cover, and the external thread is used to connect to the set pressure switching device of the next stage; the upper spring seat and the adjusting screw are both provided with coaxial through holes for the hollow adjusting screw of the set pressure switching device of the next stage to pass through.

[0014] A limiting ring is arranged outside the valve stem, and the limiting ring is located on the side of the lower spring seat away from the upper spring seat. The outer side of the end of the valve stem passing through the lower spring seat is threadedly connected with a valve stem nut to fix the valve stem to the lower spring seat.

[0015] The adjusting screw is threadedly connected with a locking nut. After the adjusting screw is adjusted into place, the locking nut is rotated until the locking nut contacts the outside of the valve cover to prevent the adjusting screw from loosening.

[0016] When the set pressure switching device is not connected to a pilot valve with a switching function, the housing is threadedly connected to a valve stem protection shell, and the valve stem protection shell is sleeved on the outside of the valve stem; when the valve cap is not connected to the next-level set pressure switching device, a sleeve is threadedly connected to the external thread position of the valve cap.

[0017] A switching method for a safety valve with a set pressure switching device that can be quickly assembled comprises: threading the housing of the set pressure switching device to the external thread position of a basic valve cap of a pilot valve with a switching function; the valve stem of the set pressure switching device passes through the basic valve cap of the pilot valve with a switching function, a hollow adjustment screw, and a spring seat on the base, and is finally pressed onto its support seat.

[0018] In summary, this application at least includes the following beneficial technical effects:

[0019] This patent innovatively designs a set pressure switching device and a pilot valve with switching function to demonstrate the effect. The overall solution has low upgrade cost, the equipment is compact and easy to use, quick to assemble, can switch multiple gears quickly, and can be used in combination with multiple devices. It realizes the switching of the set pressure of the safety valve in special working occasions. The switching process is convenient and fast, and the set pressure is accurate and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the set pressure switching device;

[0021] Figure 2 This is a typical structural diagram of a pilot-operated safety valve;

[0022] Figure 3 It is a typical structural schematic diagram of an existing pilot valve;

[0023] Figure 4 It is a schematic diagram of the pilot valve structure with switching function;

[0024] Figure 5 It is a structural diagram of a pilot valve with a switching function and a set pressure switching device;

[0025] Figure 6 It is a structural diagram of a pilot valve with switching function and two set pressure switching devices.

[0026] Description of reference numerals: 1-pilot valve with switching function (sleeve and screw plug removed); 2-set pressure switching device (valve stem protection shell removed);

[0027] 1-1, basic valve stem; 1-2, basic spring; 1-3, basic spring seat; 1-4, hollow adjustment screw;

[0028] 1-5, basic valve cover; 1-6, basic valve cap; 1-7, basic sleeve; 1-8, basic screw plug; 1-9, support seat;

[0029] 2-1, valve stem protection shell; 2-2, valve stem; 2-3, housing; 2-4, lower spring seat; 2-5, valve stem nut;

[0030] 2-6, spring; 2-7, upper spring seat; 2-8, adjusting screw; 2-9, valve cover; 2-10, locking nut;

[0031] 2-11, valve cap; 2-12, sleeve; 2-13, screw plug; 2-14, bolt; 2-15, gasket; 2-16, nut;

[0032] 0-1, main valve; 0-2, pilot valve;

[0033] 0-4 - Base adjustment screw. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] The typical structure of the existing pilot valve is as follows: Figure 3As shown, the upper part of the pilot valve is mainly composed of a basic valve stem 1-1, a basic spring 1-2, a basic spring seat 1-3, a basic adjustment screw 0-4, a basic valve cover 1-5, and a basic valve cap 1-6. The basic spring 1-2 is placed above the basic valve stem 1-1, the basic spring seat 1-3 is placed above the basic spring 1-2, the basic adjustment screw 0-4 is placed above the basic spring seat 1-3, and the basic adjustment screw 0-4, the basic valve cap 1-6 and the basic valve cap 1-5 are connected by threads. By controlling the tightening depth of the basic adjustment screw 0-4, the compression amount of the basic spring 1-2 can be changed, and the set pressure of the pilot valve can be adjusted.

[0036] The present application embodiment discloses a safety valve having a set pressure switching device that can be quickly assembled, such as Figure 5 and Figure 6 As shown, it includes a pilot valve 1 with a switching function and at least one set pressure switching device 2, each set pressure switching device 2 is connected to the pilot valve 1 with a switching function. The pilot valve 1 with a switching function includes a basic valve stem 1, and each set pressure switching device 2 is used to apply a preset pressure to the basic valve stem 1, so that the pressure set pressure of the safety valve obtained after the pilot valve 1 with a switching function is installed with the set pressure switching device 2 is adjusted.

[0037] The structure of the pilot valve 1 with switching function is as follows Figure 4As shown, the upper part of the pilot valve mainly consists of a basic valve stem 1-1, a basic spring 1-2, a basic spring seat 1-3, a hollow adjustment screw 1-4, a basic valve cover 1-5, a basic valve cap 1-6, a basic sleeve 1-7, a basic screw plug 1-8 and a support seat 1-9. The basic valve cover 1-5 is connected to the valve body, the hollow adjusting screw 1-4 is threadedly connected to the basic valve cover 1-5 and one end thereof extends into the basic valve cover 1-5, the basic valve bonnet 1-6 is threadedly connected to the outside of the basic valve cover 1-5, and the basic valve bonnet 1-6 is sleeved on the outside of the hollow adjusting screw 1-4, and the end of the basic valve bonnet 1-6 has an external thread for connecting the set pressure switching device 2; the basic spring seat 1-3 is connected to the end of the hollow adjusting screw 1-4 extending into the basic valve cover 1-5; the basic valve stem 1-1 is located on the side of the basic spring seat 1-3 away from the hollow adjusting screw 1-4, the basic spring 1-2 is located between the basic valve stem 1-1 and the basic spring seat 1-3, the other end of the basic valve stem 1-1 is connected to the valve disc, and the valve disc cooperates with the valve seat of the valve body to form a seal. A support seat 1-9 is provided at one end of the basic valve stem 1-1 facing the hollow adjustment screw 1-4, and a through hole is processed in the middle of the basic spring seat 1-3 and the hollow adjustment screw 1-4, so that the structure of the set pressure switching device 2 can penetrate from the through hole and contact with the support seat 1-9, so that the pressure applied by the set pressure switching device 2 acts on the valve disc through the support seat 1-9. By controlling the tightening depth of the hollow adjustment screw 1-4, the compression amount of the basic spring 1-2 can be changed, and the set pressure of the pilot valve can be adjusted. It can be seen that compared with the existing pilot valve, the pilot valve 1 with switching function has newly added a basic sleeve 1-7, a basic plug 1-8 and a support seat 1-9. In addition, a through hole is processed in the middle of the basic spring seat 1-3 and the hollow adjustment screw 1-4.

[0038] The basic sleeve 1-7 is connected to the basic valve cap 1-6 by threads, the basic sleeve 1-7 is connected to the basic screw plug 1-8 by threads, and the support seat 1-9 is connected to the basic valve stem 1-1 by threads. When the pilot valve 1 with switching function is not connected to the set pressure switching device 2, the basic sleeve 1-7 is threadedly connected to the external thread position of the basic valve cap 1-6 to play a protective and dustproof role. The basic screw plug 1-8 is threadedly connected to the end of the basic sleeve 1-7. When the customer performs a pressure test on the protected equipment on site and does not want the safety valve to open, the test rod is installed. The test rod passes through the hollow adjustment screw 1-4 and the spring seat 1-3 on the foundation and presses on the support seat 1-9, so that the valve cannot be opened, ensuring that the on-site equipment test is carried out normally.

[0039] Set pressure switching device 2 as Figure 1As shown, the set pressure switching device 2 includes a valve stem protective shell 2-1, a valve stem 2-2, a housing 2-3, a lower spring seat 2-4, a valve stem nut 2-5, a spring 2-6, an upper spring seat 2-7, an adjusting screw 2-8, a valve cover 2-9, a locking nut 2-10, a valve cap 2-11, a sleeve 2-12, a screw plug 2-13, a bolt 2-14, a gasket 2-15 and a nut 2-16.

[0040] The housing 2-3 and the valve cover 2-9 are assembled together by bolts 2-14 and nuts 2-16, and are sealed by gaskets 2-15. Among them, the end of the valve cover 2-9 close to the housing 2-3 is provided with a convex ring, which is inserted into the housing 2-3, and plays a role in centering with the housing 2-3 and limiting the gasket 2-15. The bottom of the housing 2-3 away from the valve cover 2-9 has a through hole, the lower spring seat 2-4 is located in the housing 2-3 and the valve cover 2-9, the lower spring seat 2-4 and the inner diameter of the housing 2-3 are matched and aligned, and the diameter of the through hole is smaller than the outer diameter of the valve cover 2-9, the upper spring seat 2-7 is located in the valve cover 2-9, and the spring 2-6 is located between the lower spring seat 2-4 and the upper spring seat 2-7. The adjusting screw 2-8 is threadedly connected to the end of the valve cover 2-9 away from the housing 2-3, and one end of the adjusting screw 2-8 extends into the valve cover 2-9 and contacts with the upper spring seat 2-7. The valve stem 2-2 passes through the lower spring seat 2-4, and a limiting ring is arranged outside the valve stem 2-2. The limiting ring is located on the side of the lower spring seat 2-4 away from the upper spring seat 2-7. The valve stem nut 2-5 is threadedly connected to the outer side of the end of the valve stem 2-2 passing through the lower spring seat 2-4, so that the valve stem 2-2 and the lower spring seat 2-4 are relatively fixed to form a whole. The depth of tightening the adjusting screw 2-8 is controlled, the compression amount of the spring 2-6 is controlled, and then the set pressure of the switching device is controlled. The valve bonnet 2-11 is threadedly connected to the end of the valve cover 2-9 away from the housing 2-3, and the valve bonnet 2-11 is sleeved on the outside of the adjusting screw 2-8. The end of the valve bonnet 2-11 away from the valve cover 2-9 is provided with an external thread, and the external thread is used to connect the set pressure switching device 2 of the next level. When the valve bonnet 2-11 is not connected to the next-stage set pressure switching device 2, the sleeve 2-12 is threadedly connected to the external thread position of the valve bonnet 2-11, and the screw plug 2-13 is threadedly connected to the sleeve 2-12.

[0041] The upper spring seat 2-7 and the adjusting screw 2-8 are both provided with coaxial through holes for the hollow adjusting screw 1-4 of the next-stage set pressure switching device 2 to pass through, so that the hollow adjusting screw 1-4 of the next-stage set pressure switching device 2 can contact the end of the valve stem 2-2 of the set pressure switching device 2 of this stage, so that the pressure of the hollow adjusting screw 1-4 of the next-stage set pressure switching device 2 acts on the valve stem 2-2 of the set pressure switching device 2 of this stage.

[0042] The locking nut 2-10 is connected to the adjusting screw 2-8 by threads. After the adjusting screw 2-8 is adjusted to the right position, the locking nut 2-10 is tightened so that the locking nut 2-10 contacts the outside of the valve cover 2-9, thereby preventing the adjusting screw 2-8 from loosening. The valve stem protection shell 2-1 is connected to the housing 2-3 by threads, thereby protecting the valve stem 2-2 in the non-working state.

[0043] The safety valve formed by assembling the pilot valve 1 with switching function and the set pressure switching device 2 is as follows: Figure 5 As shown, the housing 2-3 of the set pressure switching device 2 is threadedly connected to the external thread position of the basic valve bonnet 1-6 of the pilot valve 1 with a switching function. The valve stem 2-2 of the set pressure switching device 2 passes through the basic valve bonnet 1-6 of the pilot valve 1 with a switching function, the hollow adjusting screw 1-4, and the basic spring seat 1-3, and is finally pressed on its support seat 1-9 to achieve control of the set pressure of the pilot valve.

[0044] When the valve is tested at the factory, the pilot valve equipped with a pilot valve with a switching function is first pressure-controlled on a constant pressure platform, and the set pressure A is obtained by adjusting the adjusting screw of the pilot valve.

[0045] Then remove the sleeve and screw plug on the pilot valve, remove the valve stem protective shell of the set pressure switching device, and tighten the set pressure switching device and the pilot valve to form a new pilot valve.

[0046] The pilot valve with the new pilot valve installed is pressurized by the constant pressure platform, and the set pressure B is obtained by adjusting the adjusting screw of the set pressure switching device. At this time, a scale groove is machined for the adjusting screw of the switching device.

[0047] According to the needs, the set pressure of the switching device can be further adjusted, multiple constant pressure tests can be carried out, and multiple scale grooves can be processed on the adjusting screw to obtain the set pressures C, D, etc., so as to achieve multi-level adjustment of the valve set pressure.

[0048] If the required switching set pressure range is large, one set pressure switching device may not meet the actual demand. Therefore, multiple set pressure switching devices can be used, for example, to form a three-level structure of "pilot valve-set pressure switching device-set pressure switching device" to achieve multi-level and wide-range adjustment of the valve set pressure.

[0049] Remove the set pressure switching device from the pilot valve, and assemble the sleeve and screw plug on the pilot valve and the valve stem protection shell of the set pressure switching device.

[0050] After the pilot valve and the set pressure switching device are sent to the site, the on-site operator can assemble or disassemble the set pressure switching device on the pilot valve according to the working conditions, so as to achieve fast and accurate switching of the set pressure.

[0051] Through the above method, this patent designs a set pressure switching device and a pilot valve with switching function, which are combined to form a new pilot valve. The assembly process is convenient, the set pressure performance is stable, it can be adjusted in multiple gears, and the parts structure is lightweight. It realizes the fast and accurate switching of the set pressure of the pilot valve in special working occasions.

[0052] In order to solve the problem of achieving fast and convenient adjustment of the set pressure in special working occasions mentioned above, the set pressure switching device has the following characteristics:

[0053] 1. Structural design of set pressure switching device: An innovative set pressure switching device is designed, which can be quickly assembled with the safety valve as a whole through connection methods such as threads, buckles, and clamps, and can achieve rapid switching of the set pressure. Compared with the entire pilot valve, the switching device is light in weight and small in size, making it easy for engineers to use and install;

[0054] 2. Multiple gears can be switched quickly: There are several scale grooves on the adjusting screw of the switching device. By screwing the adjusting screw to the position of a specific scale groove, the valve set pressure can be quickly adjusted in multiple gears and within a small range without suitable constant pressure equipment, meeting different working conditions.

[0055] 3. Multiple devices can be used in combination: The connection structure of the switching device adopts a unified design. One or more switching devices can be installed according to the needs to achieve multi-level and wide-range rapid adjustment of the valve set pressure to meet different working conditions.

[0056] The pilot valve with switching function has the following characteristics:

[0057] Structural design of pilot valve: An innovative pilot valve is designed to be used with a switching device. A threaded connection is added to the top of the valve cap, the adjustment screw and the upper spring seat are designed with a through-hole type, and a support seat is added to the valve stem. It not only meets the requirements of the switching function, but also retains the original structure and performance of the pilot valve, ensures the accuracy and stability of the set pressure, and reduces the cost of product debugging and upgrading.

[0058] A switching method for a safety valve having a set pressure switching device that can be quickly assembled, comprising:

[0059] S1: Determine the number of stages of the set pressure switching device 2 that needs to be connected to the pilot valve 1 with switching function according to the set pressure required for the use condition;

[0060] For example: if the use condition requires n-level set pressure, then the pilot valve 1 with switching function needs to be connected to n-1 set pressure switching devices 2; the following is explained using the example of requiring 2-level set pressure;

[0061] S2: Connect the pilot valve 1 with a switching function to the experimental equipment, and adjust the set pressure of the pilot valve 1 with a switching function to a first set pressure by rotating the hollow adjustment screw 1-4. The first set pressure is used under the first working condition;

[0062] S3: Connect the first-stage set pressure switching device 2 to the pilot valve 1 with a switching function to obtain a first adjusted safety valve, connect the first adjusted safety valve to the experimental equipment, and adjust the set pressure of the first adjusted safety valve to the second set pressure by turning the adjusting screw 2-8 of the first-stage set pressure switching device 2. The second set pressure is greater than the first set pressure. The first set pressure is used under the second working condition.

[0063] The typical structure of a pilot operated safety valve is as follows: Figure 2 As shown, it consists of main valve 0-1 and pilot valve 0-2.

[0064] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0065] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A safety valve with a set pressure switching device that can be quickly assembled, characterized in that: The invention comprises a pilot valve (1) with a switching function and at least one set pressure switching device (2), wherein the set pressure switching device (2) is connected to the pilot valve (1) with a switching function, and each set pressure switching device (2) is used to apply a preset pressure to a basic valve stem (1-1), so that the set pressure of the safety valve obtained after the pilot valve (1) with a switching function is installed with the set pressure switching device (2) is adjusted.

2. The safety valve with a set pressure switching device that can be quickly assembled according to claim 1, characterized in that: The pilot valve (1) with switching function also includes a valve body, a basic valve cover (1-5), a basic spring (1-2), a basic spring seat (1-3), a hollow adjustment screw (1-4) and a basic valve cap (1-6); the basic valve cover (1-5) is connected to the valve body, the hollow adjustment screw (1-4) is threadedly connected to the basic valve cover (1-5) and one end thereof extends into the basic valve cover (1-5), the basic valve cap (1-6) is threadedly connected to the outside of the basic valve cover (1-5), and the basic valve cap (1-6) is sleeved on the outside of the hollow adjustment screw (1-4), and the end of the basic valve cap (1-6) has an external thread for connecting to the set pressure switching device (2); the basic spring seat (1-3) is connected to the The end of the hollow adjustment screw (1-4) extends into the basic valve cover (1-5); the basic valve stem (1-1) is located on the side of the basic spring seat (1-3) away from the hollow adjustment screw (1-4), the basic spring (1-2) is located between the basic valve stem (1-1) and the basic spring seat (1-3), the other end of the basic valve stem (1-1) is connected to the valve disc, and the valve disc cooperates with the valve seat of the valve body to form a seal; through holes are processed between the basic spring seat (1-3) and the hollow adjustment screw (1-4), so that the structure of the set pressure switching device (2) can pass through the through hole, so that the pressure applied by the set pressure switching device (2) acts on the basic valve stem (1-1), and then acts on the valve disc.

3. The safety valve with a set pressure switching device that can be quickly assembled according to claim 2, characterized in that: A support seat (1-9) is provided at one end of the basic valve stem (1-1) facing the hollow adjustment screw (1-4), and the structure of the set pressure switching device (2) can be inserted into the through hole and contact the support seat (1-9), so that the pressure applied by the set pressure switching device (2) acts on the valve disc through the support seat (1-9).

4. The safety valve with a set pressure switching device that can be quickly assembled according to claim 2, characterized in that: When the pilot valve (1) with a switching function is not connected to the set pressure switching device (2), the external thread at the end of the basic valve cap (1-6) is threadedly connected to the basic sleeve (1-7), and the basic sleeve (1-7) blocks the end of the basic valve cap (1-6).

5. The safety valve with a set pressure switching device that can be quickly assembled according to claim 4, characterized in that: The basic sleeve (1-7) is provided with an opening at a position directly opposite to the end of the basic valve cap (1-6), and a basic screw plug (1-8) is threadedly connected to the opening of the basic sleeve (1-7).

6. The safety valve with a set pressure switching device that can be quickly assembled according to claim 1, characterized in that: The set pressure switching device (2) comprises a valve stem (2-2), a housing (2-3), a lower spring seat (2-4), a spring (2-6), an upper spring seat (2-7), an adjusting screw (2-8), a valve cover (2-9) and a valve bonnet (2-11); the housing (2-3) and the valve cover (2-9) are fixedly and sealedly connected; a bottom of the housing (2-3) away from the valve cover (2-9) has a through hole, the lower spring seat (2-4) and the upper spring seat (2-7) are located in the housing (2-3) and the valve cover (2-9), and the spring (2-6) is located between the lower spring seat (2-4) and the upper spring seat (2-7); the adjusting screw (2-8) is threadedly connected to one end of the valve cover (2-9) away from the housing (2-3), and the adjusting screw (2-8) is threadedly connected to the end of the valve cover (2-9) away from the housing (2-3). The valve stem (2-2) is fixedly connected to the lower spring seat (2-4) and passes through the lower spring seat (2-4) in a direction away from the upper spring seat (2-7); the valve cap (2-11) is threadedly connected to the end of the valve cap (2-9) away from the housing (2-3), and the valve cap (2-11) is sleeved on the outside of the adjusting screw (2-8); the end of the valve cap (2-11) away from the valve cap (2-9) is provided with an external thread, and the external thread is used to connect to the next level set pressure switching device (2); the upper spring seat (2-7) and the adjusting screw (2-8) are both provided with coaxial through holes for the hollow adjusting screw (1-4) of the next level set pressure switching device (2) to pass through.

7. The safety valve with a set pressure switching device that can be quickly assembled according to claim 6, characterized in that: A limiting ring is arranged outside the valve stem (2-2), and the limiting ring is located on the side of the lower spring seat (2-4) away from the upper spring seat (2-7). The outer side of the end of the valve stem (2-2) passing through the lower spring seat (2-4) is threadedly connected with a valve stem nut (2-5) to fix the valve stem (2-2) and the lower spring seat (2-4).

8. The safety valve with a set pressure switching device that can be quickly assembled according to claim 6, characterized in that: The adjusting screw (2-8) is threadedly connected with a locking nut (2-10). After the adjusting screw (2-8) is adjusted into place, the locking nut (2-10) is rotated until the locking nut (2-10) contacts the outside of the valve cover (2-9), so as to prevent the adjusting screw (2-8) from loosening.

9. The safety valve with a set pressure switching device that can be quickly assembled according to claim 6, characterized in that: When the set pressure switching device (2) is not connected to a pilot valve (1) having a switching function, the housing (2-3) is threadedly connected to a valve stem protection shell (2-1), and the valve stem protection shell (2-1) is sleeved on the outside of the valve stem (2-2); when the valve cap (2-11) is not connected to a next-level set pressure switching device (2), a sleeve (2-12) is threadedly connected to the external thread position of the valve cap (2-11).

10. The switching method of a safety valve with a set pressure switching device that can be quickly assembled according to any one of claims 1 to 9, characterized in that: include: The housing (2-3) of the set pressure switching device (2) is connected to the external thread position of the basic valve cap (1-6) of the pilot valve (1) with a switching function through threads, and the valve stem (2-2) of the set pressure switching device (2) passes through the basic valve cap (1-6) of the pilot valve (1) with a switching function, the hollow adjustment screw (1-4), and the basic spring seat (1-3), and finally presses on its support seat (1-9).

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