Passive numerical control valve lock

Abstract

The utility model provides a passive numerical control valve lock, and belongs to the technical field of valves. The magnetic locking valve solves the problem that an existing magnetic locking valve can still be easily unlocked without a special handle. The passive numerical control valve lock comprises a key, an inner cylinder and a shell, a controller with an identity recognition module, a driving piece connected with the controller and a positioning piece are further arranged in the shell, a first positioning opening is formed in the shell, and a second positioning opening is correspondingly formed in the inner cylinder. The driving piece can drive the positioning piece to penetrate into the first positioning opening and the second positioning opening so as to position the axial relative positions of the inner cylinder and the shell, a locking opening is formed in the side portion of the lower end of the inner cylinder in a penetrating mode, a locking piece is arranged in the locking opening, and a concave receding groove is formed in the inner side of the shell. The locking piece can move into the receding groove so that the inner end of the locking piece can retract into the locking opening. The passive numerical control valve lock has the advantage of high use safety.

Description

Technical Field

[0001] This utility model belongs to the field of valve technology and relates to a passive CNC valve lock. Background Technology

[0002] Valves are the most commonly used flow control components in various pipe networks. They are operated by a handle that drives the valve stem, which in turn moves the valve core, thus adjusting the valve opening. However, in some residential areas, ordinary valves can be arbitrarily opened and closed at pipe locations that require property management, making management difficult.

[0003] To address this issue, a magnetic locking valve was designed and a Chinese patent was applied for, with application number 201720043252.1 and publication number CN206377335U. This magnetic locking valve includes a valve body, a valve cap connected to the upper end of the valve body, and a locking cap fitted onto the valve cap. A magnetic locking mechanism is provided between the valve cap and the locking cap. The valve body contains a valve stem that controls the opening and closing of the valve when rotated. The upper end of the valve stem passes upward through the valve cap and extends into the locking cap. The design principle of this valve is to use a magnetic locking mechanism between the valve cap and the locking cap, setting several magnetic points—that is, several magnets—to lock the circumferential position of the valve stem, preventing it from rotating. A special handle that cooperates with the magnets on the magnetic locking mechanism is needed to move the magnets and release the lock before the valve can be turned; otherwise, it cannot be opened, thus providing a certain degree of security.

[0004] However, with the popularization of the magnetic locking valve principle, since it uses a magnet for locking, in reality, the magnetic locking mechanism can be unlocked directly with a magnet without using a special handle, so safety and specialization are still difficult to guarantee. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a passive CNC valve lock, which solves the problem that existing magnetic locking valves can be easily unlocked without a dedicated handle.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A passive CNC valve lock includes a key, a cylindrical inner cylinder, and a barrel-shaped outer shell. The open end of the outer shell faces downward and is fitted onto the outside of the inner cylinder. The outer shell is characterized by housing a controller with an identification module, a drive unit connected to the controller, and a positioning unit. The outer shell has a first positioning port, and the inner cylinder has a corresponding second positioning port. The drive unit can drive the positioning unit to pass through the first and second positioning ports to position the axial relative positions of the inner cylinder and the outer shell. A locking port is provided through the lower side of the inner cylinder, and a locking unit is provided within the locking port, with its inner end protruding from the inner wall of the inner cylinder. The inner side of the outer shell has a recessed clearance groove located below the locking port within the outer shell. When the outer shell moves upward relative to the inner cylinder, the locking unit can move into the clearance groove to retract its inner end into the locking port.

[0008] This passive CNC valve lock requires the use of a valve body with a radially recessed neck, such as the magnetic locking valve in the background art where the valve body neck has a recess on the outer side. It should be noted that this type of valve body neck with a ring-shaped recess on the outer side is a common structure in existing valves and does not involve structural innovation. This passive CNC valve lock is designed specifically for the characteristics of this type of existing valve body structure. During installation, the existing valve handle is removed, and the inner cylinder and outer shell are fitted over the outer side of the valve body neck to completely cover the outer end of the valve stem. Without removing this passive CNC valve lock, the valve stem cannot be operated to control the valve.

[0009] When this passive CNC valve is locked, the outer shell moves downward relative to the inner cylinder, causing the positioning groove to misalign the locking element and the locking port. Under the constraint of the inner wall of the outer shell, the inner end of the locking element protrudes through the inner wall of the inner cylinder and extends into the recessed position of the valve neck, achieving axial restraint between the inner cylinder and the valve neck, preventing the inner cylinder from moving upward out of the valve body neck. Simultaneously, the controller controls the drive unit to drive the positioning element into positioning ports one and two to position the axial relative position of the inner cylinder and the outer shell, preventing the outer shell from moving upward relative to the inner cylinder and thus releasing the lock.

[0010] When unlocking is required, a special key with an identification code is used in conjunction with the identification module on the controller for identity verification. After successful verification, the controller controls the drive component to drive the positioning component to move in the opposite direction, exiting from positioning port one and positioning port two, releasing the axial positioning of the outer shell and inner cylinder. The outer shell moves upward, so that the clearance groove is aligned with the locking port. The locking component can then move into the clearance groove to retract its inner end into the locking port, releasing the axial restriction between the inner cylinder and the valve body. The inner cylinder can then be removed, and the valve opening can be controlled by using the handle in conjunction with the valve stem.

[0011] During the use of this passive CNC valve lock, a special key with an identification code is required to unlock it. Even if an outsider understands its principle, they cannot open it at will, thus ensuring higher security and reliability. Furthermore, the use of a mechanical locking structure to lock the inner cylinder and valve body, instead of directly using a positioning component, allows for the selection of larger and stronger locking parts, resulting in better connection strength. This also avoids affecting the normal operation of the electronically controlled drive components, ensuring both service life and safety.

[0012] In the aforementioned passive CNC valve lock, the inner wall of the outer shell has a recessed, elongated limiting groove, the length of which is aligned with the axial direction of the outer shell. A limiting pin is axially fixed to the side of the inner cylinder, extending into the limiting groove and moving up and down along it. When the limiting pin abuts against the lower side wall of the limiting groove, the clearance groove and the locking port are aligned. The cooperation between the limiting pin and the limiting groove not only guides the axial movement of the outer shell relative to the inner cylinder but also prevents the outer shell from detaching from the inner cylinder and affecting normal use. Furthermore, the length design of the limiting groove limits the axial movement distance of the outer shell relative to the inner cylinder, facilitating precise alignment of the clearance groove and locking port during manual operation and simplifying unlocking.

[0013] In the aforementioned passive CNC valve lock, the inner cylinder has a recessed limiting hole on its side. The limiting pin is rod-shaped, with one end extending into the limiting hole and the other end passing through the limiting groove. A limiting spring is also provided inside the limiting hole, with its two ends abutting against the bottom of the limiting hole and the limiting pin, respectively. The limiting spring and limiting pin facilitate the installation of the limiting pin and provide better guidance for the movement of the outer casing.

[0014] In the aforementioned passive CNC valve lock, the clearance groove is annular and opens around the axis of the outer shell, and the number of locking ports is several and distributed around the axis of the inner cylinder. The number of locking elements is the same as the number of locking ports, and the two are arranged in a one-to-one correspondence. The setting of several locking elements further enhances the locking strength of the valve body, while the annular clearance groove can easily align with the locking ports, requiring low positioning accuracy.

[0015] In the aforementioned passive CNC valve lock, the locking element is a spherical steel ball, and the diameter of the inner end of the locking port is smaller than the diameter of the steel ball. Using a spherical steel ball as the locking element facilitates the inward movement of the locking element when the outer shell moves downward relative to the inner cylinder, and the outward movement of the locking element when the outer shell moves upward relative to the inner cylinder. The smaller diameter of the locking port prevents the steel ball from falling out from the inside of the inner cylinder.

[0016] In the aforementioned passive CNC valve lock, an unlocking spring is also provided between the outer shell and the inner cylinder. The two ends of the unlocking spring abut against the outer shell and the inner cylinder respectively, and the outer shell can move axially upward relative to the inner cylinder under the elastic force of the unlocking spring. When the drive unit controls the positioning component to retract, the unlocking spring can automatically spring the outer shell upward and cause the steel ball to move outward to release the lock, making it convenient to use.

[0017] In the aforementioned passive CNC valve lock, the outer casing also includes a mounting base. The lower part of the mounting base is located inside the upper port of the inner cylinder, and both the drive component and the controller are fixed to the mounting base. Fixing the drive component and the controller to the mounting base inside the upper port of the inner cylinder not only makes full use of the space inside the inner cylinder but also shields the upper end of the valve stem that passes through the inner cylinder, preventing abnormal operation. Furthermore, it completely separates the drive component and the controller from the outside, protecting their safety and stability.

[0018] In the aforementioned passive CNC valve lock, the top of the outer casing has an openable and closable top cover, and a power interface is fixed inside the casing. This power interface is electrically connected to the controller and drive unit, and the opening of the power interface faces the top cover. The power interface eliminates the need for a built-in battery in this passive CNC valve lock, instead using an external power source. This avoids the degradation of the built-in battery due to prolonged disuse. Furthermore, the absence of a built-in battery necessitates the use of an external power source to open the lock, further enhancing security. For ease of carrying and use, the external power source can be integrated with the key into a handheld terminal. This handheld terminal serves both as an identification code and an electrical connection to the power interface to supply power to the controller and drive unit.

[0019] In the aforementioned passive CNC valve lock, the outer shell further includes a main body, and a top cover is rotatably connected to the top of the main body. A magnet and an opening / closing spring are disposed off-center on the main body. The top cover has a corresponding notch, and the magnet can extend into the notch under the elastic force of the opening / closing spring, thus restricting the circumferential position of the top cover. The top cover is rotatably connected to the top of the main body, meaning it is fixed to the main body by rotating circumferentially relative to it, such as through a threaded connection or a snap-fit ​​connection after rotation. A magnetic locking structure is designed between the main body and the top cover to protect the opening and closing of the top cover, achieving multiple locking mechanisms for this passive CNC valve lock and further improving security.

[0020] In the aforementioned passive CNC valve lock, the top of the main body has an inverted L-shaped locking portion, which includes a vertical section and a horizontal section, both elongated and perpendicular to each other. The top cover has a block-shaped locking block. When the top cover rotates circumferentially relative to the main body, the locking block can extend into the lower side of the horizontal section and abut against the vertical section. The inverted L-shaped locking portion forms a latch with an opening on one side. The locking block of the top cover can be horizontally locked into the latch of the locking portion to achieve axial fixation between the top cover and the main body. Conversely, the locking block can be disengaged from the latch by moving in the opposite direction, releasing the axial fixation between the top cover and the main body.

[0021] Compared to existing technologies, this passive CNC valve lock requires a special key with an identification code to unlock, making it impossible for unauthorized individuals to open even if they understand its workings, thus offering higher security and reliability. Furthermore, by employing a mechanical locking mechanism to lock the inner cylinder and valve body instead of directly using a positioning component, the lock can utilize larger and stronger parts, resulting in a stronger connection. This also avoids affecting the normal operation of the electronically controlled drive components, ensuring both longevity and safety. Attached Figure Description

[0022] Figure 1 This is a cross-sectional structural diagram of a passive CNC valve lock.

[0023] Figure 2 This is a cross-sectional structural diagram of the passive CNC valve lock from another perspective.

[0024] Figure 3 This is a cross-sectional structural diagram of the locking magnet of the passive CNC valve.

[0025] Figure 4 This is an exploded view of a passive CNC valve lock.

[0026] In the diagram, 1. Inner cylinder; 1a. Positioning port 2; 1b. Locking port; 1c. Limiting hole; 2. Outer shell; 2a. Positioning port 1; 2b. Clearance groove; 2c. Limiting groove; 2d. Mounting base; 2e. Top cover; 2f. Split part 1; 2g. Split part 2; 3. Controller; 3a. Power interface; 4. Drive component; 5. Positioning component; 6. Locking component; 7. Limiting pin; 8. Limiting spring; 9. Unlocking spring; 10. Magnet; 11. Opening and closing spring. Detailed Implementation

[0027] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0028] like Figure 1As shown, this passive CNC valve lock includes a key, a cylindrical inner cylinder 1, and a barrel-shaped outer shell 2. The open end of the outer shell 2 faces downward and is fitted onto the outside of the inner cylinder 1.

[0029] The upper inner side of the outer shell 2 also has an inwardly extending mounting base 2d, and the lower end of the mounting base 2d extends into the upper port of the inner cylinder 1. A controller 3 with an identification module and a drive component 4 connected to the controller 3 are fixed on the mounting base 2d. A power interface 3a is fixed on the controller 3, and the opening of the power interface 3a faces upward. A positioning component 5 is located at the output end of the drive component 4. A positioning port 2a is provided through the side of the mounting base 2d of the outer shell 2, and a corresponding positioning port 1a is provided on the upper side of the inner cylinder 1. The drive component 4 can drive the positioning component 5 to pass through the positioning port 2a and the positioning port 1a. In this embodiment, a handheld terminal is selected as the key. It has a dedicated identification code and can be connected to the power interface 3a via a data cable. It exchanges data while supplying power to complete the identification. Here, according to the actual production and operation needs, the identification code on one handheld terminal can unlock multiple passive CNC valve locks. The controller 3 can be an existing control chip, and the power interface 3a can be a type-C interface. The drive component 4 is an electromagnet, and the positioning component 5 can be the armature of the electromagnet.

[0030] like Figure 3 As shown, the outer casing 2 includes a main body and a top cover 2e. The top cover 2e is rotatably connected to the top of the main body. A magnet 10 and an opening / closing spring 11 are disposed off-center at the top of the main body. The bottom of the top cover 2e has a downwardly protruding, annular protrusion with a notch on the side. The magnet 10 can extend into the notch under the elastic force of the opening / closing spring 11 and restrict the circumferential position of the top cover 2e. In this embodiment, the top of the main body off-center has a protruding, inverted L-shaped latching part. The latching part includes a vertical section and a horizontal section, both elongated and perpendicular to each other. One end of the horizontal section is integrated with the upper end of the vertical section, thereby forming a latch with a side opening below the horizontal section and on one side of the vertical section. The lower end of the top cover 2e has an inwardly protruding, block-shaped latching block on the side. When the top cover 2e rotates circumferentially relative to the main body, the latching block can extend into the latch, i.e., it is located below the horizontal section and can abut against the vertical section.

[0031] like Figure 2As shown, a locking opening 1b is provided through the side of the lower end of the inner cylinder 1. A locking member 6 is provided in the locking opening 1b and the inner end of the locking member 6 protrudes from the inner wall of the inner cylinder 1. The inner side of the outer shell 2 has a recessed relief groove 2b and the relief groove 2b is located below the position of the locking opening 1b inside the outer shell 2. When the outer shell 2 moves upward relative to the inner cylinder 1, the locking member 6 can move into the relief groove 2b so that the inner end of the locking member 6 retracts into the locking opening 1b. In this embodiment, the clearance groove 2b is annular and opened around the axis of the outer shell 2. The number of locking ports 1b is several and evenly distributed around the axis of the inner cylinder 1. The number of locking elements 6 is the same as the number of locking ports 1b and they are arranged in a one-to-one correspondence. The locking element 6 is a spherical steel ball. The diameter of the locking port 1b gradually decreases from the outside to the inside, and the diameter of the inner end of the locking port 1b is smaller than the diameter of the steel ball to prevent the steel ball from falling out of the inner cylinder 1. An unlocking spring 9 is also provided between the outer shell 2 and the inner cylinder 1. The unlocking spring 9 is vertically arranged, and the two ends of the unlocking spring 9 abut against the outer shell 2 and the inner cylinder 1 respectively. The outer shell 2 can move axially upward relative to the inner cylinder 1 under the elastic force of the unlocking spring 9.

[0032] The inner wall of the outer shell 2 has a recessed, elongated limiting groove 2c, and the length direction of the limiting groove 2c is consistent with the axial direction of the outer shell 2. A limiting pin 7 is axially fixed on the side of the inner cylinder 1. The limiting pin 7 extends into the limiting groove 2c and can move up and down along the limiting groove 2c. When the limiting pin 7 abuts against the lower side wall of the limiting groove 2c, the position of the positioning groove 2b is opposite to that of the locking port 1b. In this embodiment, the side of the inner cylinder 1 has a recessed limiting hole 1c. The limiting pin 7 is rod-shaped, with one end extending into the limiting hole 1c and the other end passing through the limiting groove 2c. A limiting spring 8 is also provided in the limiting hole 1c. The two ends of the limiting spring 8 abut against the bottom of the limiting hole 1c and the limiting pin 7, respectively.

[0033] In addition, such as Figure 4 As shown, for ease of production and assembly, the main body of the outer shell 2 is divided into a cylindrical split body 2f and a cylindrical split body 2g. The cylindrical split body 2f is fitted onto the outside of the cylindrical split body 2g, and the two are fixed together by fasteners. The mounting base 2d is located inside the cylindrical split body 2g and is integrated with it. The clearance groove 2b is opened on the inner side of the lower end of the cylindrical split body 2g, and the limiting groove 2c is opened through the side of the upper end of the cylindrical split body 2g. The upper end of the cylindrical split body 2f is connected to the top cover 2e.

[0034] This passive CNC valve lock needs to be used with a valve body with a radially recessed neck. The structure of the annular recess on the outside of the neck of this type of valve body is a common structure in existing valves and does not involve structural innovation. This passive CNC valve lock is designed to address the characteristics of this type of existing valve body structure.

[0035] During installation, the existing valve handle is removed to expose the upper end of the valve stem. The inner cylinder 1 and the outer shell 2 are then fitted onto the outside of the valve body neck to completely cover the upper end of the valve stem. Without removing the lock of this passive CNC valve, the valve stem cannot be operated to control the valve.

[0036] When the passive CNC valve is locked, the handheld terminal is plugged into the power interface 3a. The outer shell 2 moves downward relative to the inner cylinder 1, causing the positioning groove 2b to misalign with the locking member 6 and the locking port 1b. The inner wall of the outer shell 2 acts on the outer end of the spherical locking member 6, causing the locking member 6 to roll inward and its inner end to pass through the inner wall of the inner cylinder 1 and extend into the recessed position of the valve neck, thus achieving axial limiting of the inner cylinder 1 and the valve neck, preventing the inner cylinder 1 from moving upward out of the valve body neck. At the same time, the controller 3 controls the drive member 4 to drive the positioning member 5 to enter the positioning port 1 2a and positioning port 2 1a to position the axial relative position of the inner cylinder 1 and the outer shell 2, preventing the outer shell 2 from moving upward relative to the inner cylinder 1 and thus unlocking the valve. The handheld terminal is then removed, and the top cover 2e is placed on top of the main body to protect the power interface 3a.

[0037] When unlocking is required, a handle with a corresponding magnet 10 is fitted onto the outside of the top cover 2e. The magnet 10 inside the handle generates a magnetic attraction to the magnet 10 inside the outer casing 2, causing it to overcome the elastic force of the opening and closing spring 11 and move out of the notch on the top cover 2e. By rotating the top cover 2e circumferentially with the handle, it is detached from the top of the main body, exposing the power interface 3a. Here, the engagement between the magnet 10 on the handle and the magnet 10 inside the main body is similar to that of a magnetic locking valve.

[0038] The handheld terminal is plugged into the power interface 3a via a data cable. Data exchange occurs simultaneously with power supply, and the identification code within the handheld terminal is used in conjunction with the identification module on the controller 3 for authentication. The structure and working principle of the identification process between the terminal and the controller 3 are existing technologies and will not be described in detail here.

[0039] After successful verification, controller 3 controls drive component 4 to drive positioning component 5 to move in the opposite direction, exiting from positioning port 1 (2a) and positioning port 2 (1a), releasing the axial positioning of outer shell 2 and inner cylinder 1. Under the elastic force of unlocking spring 9, outer shell 2 moves axially upward relative to inner cylinder 1 until limit pin 7 abuts against the lower groove wall of limit groove 2c, then clearance groove 2b is aligned with locking port 1b. Locking component 6 rolls outward along the inclined side wall of locking port 1b into clearance groove 2b, and the inner end of locking component 6 is completely retracted into inner cylinder 1, releasing the axial restriction between inner cylinder 1 and valve body. Inner cylinder 1 and outer shell 2 can then be removed, and the valve opening can be controlled by operating the handle in conjunction with the valve stem.

[0040] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A passive CNC valve lock, comprising a key, a cylindrical inner cylinder (1), and a barrel-shaped outer shell (2), wherein the open end of the outer shell (2) faces downward and is fitted over the outside of the inner cylinder (1), characterized in that, The outer shell (2) is further provided with a controller (3) having an identification module, a drive component (4) connected to the controller (3), and a positioning component (5). The outer shell (2) has a positioning port one (2a), and the inner cylinder (1) has a corresponding positioning port two (1a). The drive component (4) can drive the positioning component (5) to penetrate into the positioning port one (2a) and the positioning port two (1a) to position the axial relative position of the inner cylinder (1) and the outer shell (2). The side of the lower end of the inner cylinder (1) penetrates... The outer shell (2) has a locking opening (1b) and a locking member (6) is provided inside the locking opening (1b). The inner end of the locking member (6) protrudes from the inner wall of the inner cylinder (1). The inner side of the outer shell (2) has a recessed relief groove (2b) and the relief groove (2b) is located below the position of the locking opening (1b) inside the outer shell (2). When the outer shell (2) moves upward relative to the inner cylinder (1), the locking member (6) can move into the relief groove (2b) so that the inner end of the locking member (6) retracts into the locking opening (1b).

2. The passive CNC valve lock according to claim 1, characterized in that, The inner wall of the outer shell (2) has a recessed, elongated limiting groove (2c), and the length direction of the limiting groove (2c) is consistent with the axial direction of the outer shell (2). The inner cylinder (1) is axially fixed with a limiting pin (7). The limiting pin (7) extends into the limiting groove (2c) and can move up and down along the limiting groove (2c). When the limiting pin (7) abuts against the lower side wall of the limiting groove (2c), the position of the clearance groove (2b) is opposite to that of the locking port (1b).

3. A passive CNC valve lock according to claim 2, characterized in that, The inner cylinder (1) has a recessed limiting hole (1c) on its side. The limiting pin (7) is rod-shaped, with one end extending into the limiting hole (1c) and the other end passing through the limiting groove (2c). A limiting spring (8) is also provided in the limiting hole (1c). The two ends of the limiting spring (8) abut against the bottom of the limiting hole (1c) and the limiting pin (7), respectively.

4. A passive CNC valve lock according to claim 1, 2, or 3, characterized in that, The clearance groove (2b) is annular and opened around the axis of the outer shell (2). The number of locking ports (1b) is several and distributed around the axis of the inner cylinder (1). The number of locking elements (6) is the same as the number of locking ports (1b) and the two are set in a one-to-one correspondence.

5. A passive CNC valve lock according to claim 4, characterized in that, The locking element (6) is a spherical steel ball, and the diameter of the inner end of the locking port (1b) is smaller than the diameter of the steel ball.

6. A passive CNC valve lock according to claim 1, 2, or 3, characterized in that, An unlocking spring (9) is also provided between the outer shell (2) and the inner cylinder (1). The two ends of the unlocking spring (9) abut against the outer shell (2) and the inner cylinder (1) respectively, and the outer shell (2) can move axially upward relative to the inner cylinder (1) under the elastic force of the unlocking spring (9).

7. A passive CNC valve lock according to claim 1, 2, or 3, characterized in that, The outer casing (2) also has a mounting base (2d), the lower part of which is located inside the upper port of the inner cylinder (1), and the drive unit (4) and the controller (3) are both fixed on the mounting base (2d).

8. A passive CNC valve lock according to claim 1, 2, or 3, characterized in that, The housing (2) has an openable and closable top cover (2e) on the top. A power interface (3a) is also fixed inside the housing (2). The power interface (3a) is electrically connected to the controller (3) and the drive unit (4) mentioned above, and the opening of the power interface (3a) is set towards the top cover (2e).

9. A passive CNC valve lock according to claim 8, characterized in that, The outer shell (2) also includes a main body, and the top cover (2e) is rotatably connected to the top of the main body. A magnet (10) and an opening and closing spring (11) are provided off-center on the main body. The top cover (2e) has a corresponding notch. The magnet (10) can extend into the notch under the elastic force of the opening and closing spring (11) and restrict the circumferential position of the top cover (2e).

10. A passive CNC valve lock according to claim 9, characterized in that, The top of the main body has an inverted L-shaped snap-fit ​​portion, which includes a vertical section and a horizontal section that are both long strips and arranged perpendicularly to each other. The top cover (2e) has a block-shaped snap-fit ​​block. When the top cover (2e) rotates circumferentially relative to the main body, the snap-fit ​​block can extend into the lower side of the horizontal section and abut against the vertical section.

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