CN223447802U

CN223447802U - Irrigation valve

Info

Publication number: CN223447802U
Application number: CN202422844193.0U
Authority: CN
Inventors: 李松杰; 张燕伟
Original assignee: Yuyao Puro Water Purification Equipment Co ltd
Current assignee: Yuyao Puro Water Purification Equipment Co ltd
Priority date: 2024-11-21
Filing date: 2024-11-21
Publication date: 2025-10-17
Anticipated expiration: 2034-11-21

Abstract

The utility model discloses an irrigation valve, wherein a flow regulating component comprises a diaphragm structure above a water inlet of the irrigation valve, and the tightness of a spring can be regulated by connecting the spring above the diaphragm structure with a tightness regulating structure, so that the pressure required by opening the diaphragm structure is changed, and further the flow control is realized. The rotary switch is arranged at the connecting position of the upper body and the lower body of the electromagnetic valve, and can periodically open the pilot hole through manual rotation when the electromagnet cannot work to open the pilot hole, so that the pilot hole is opened, the irrigation valve is opened, the emergency capacity is strong, the reliability is good, and the maintenance is convenient. And be equipped with filter screen piece filtration aquatic granule great impurity in the pilot hole position department of diaphragm structure and can reduce the wearing and tearing of the inside important subassembly of irrigation valve, and dismantle conveniently.

Description

Irrigation valve

Technical Field

The utility model relates to the field of pilot electromagnetic valve assemblies, in particular to an irrigation valve.

Background

Irrigation is the most basic and widely used technology in the agricultural field, the growth of crops can be determined by the irrigation technology, irrigation is carried out through a solenoid valve control water pipe at present very often, but the environment where a valve is located in agricultural production is severe, and an irrigated water source is often mixed with more impurities, cannot be maintained frequently and is easily damaged due to the influence of corrosion and the like.

The existing agricultural electromagnetic irrigation valve cannot be used as an electromagnetic switch function failure valve and cannot adjust the flow when the valve is opened. In the "low-in high-out plastic solenoid valve" disclosed in the publication No. CN211525652U, the solenoid valve can only control the opening and closing of the valve by the electromagnet, but lacks a manual valve opening and closing and a device for adjusting the flow, has weak emergency capability, poor durability, and needs frequent maintenance. And the water entering the pilot hole has more sundries, so that the abrasion of the electromagnetic valve is easy to accelerate.

Disclosure of utility model

Aiming at the defects of the prior art, the utility model provides an irrigation valve, wherein a flow regulating component comprises a diaphragm structure above a water inlet of the irrigation valve, and the tightness of a spring can be regulated by connecting the spring with the tightness regulating structure above the diaphragm structure, so that the pressure required by opening the diaphragm structure is changed, and the flow control is realized. The rotary switch is arranged at the connecting position of the upper body and the lower body of the electromagnetic valve, and can periodically open the pilot hole through manual rotation when the electromagnet cannot work to open the pilot hole, so that the pilot hole is opened, the irrigation valve is opened, the emergency capacity is strong, the reliability is good, and the maintenance is convenient. And be equipped with filter screen piece filtration aquatic granule great impurity in the pilot hole position department of diaphragm structure and can reduce the wearing and tearing of the inside important subassembly of irrigation valve, and dismantle more conveniently.

The present utility model achieves the above technical object by the following means.

The utility model provides an irrigation valve, includes the solenoid valve upper body and solenoid valve lower body, the top of the water inlet of irrigation valve is equipped with flow control part, the top of the delivery port of irrigation valve is equipped with the solenoid valve upper body.

The connection position of the upper electromagnetic valve body and the lower electromagnetic valve body is provided with a knob switch mounting hole, and the knob switch is mounted in the knob switch mounting hole.

Further, the flow regulating component comprises a tightness regulating structure and a diaphragm structure, a spring is connected between the tightness regulating structure and the diaphragm structure, the diaphragm structure comprises a guide plate and a diaphragm sheet, the diaphragm is clamped between the guide plate and the diaphragm sheet, a hollow cylinder is extended upwards and downwards in the middle of the guide plate in a protruding mode, and threads are arranged on the outer side of the hollow cylinder below the guide plate.

Further, the hollow cylinder of the guide plate is sleeved with a diaphragm, a sealing gasket and a diaphragm locking gasket from top to bottom, the sealing gasket is semi-embedded into the diaphragm, and the upper surface of the diaphragm locking gasket is in contact with the lower surface of the sealing gasket.

A screw cap is screwed at the thread of the hollow cylinder of the guide plate, and a filter screen is arranged between the screw cap and the opening of the hollow cylinder.

Further, the water inlet is upwards arranged at the opening of the lower body of the electromagnetic valve and is in contact with the lower end face of the sealing gasket below the flow regulating component, the axes of the water inlet and the water outlet are at the same height, and a valve wall is arranged at the position between the water inlet and the water outlet and close to the water outlet to separate the water inlet from the water outlet.

Further, the flow regulating part and the electromagnetic valve lower body are provided with openings at positions close to the water outlet, and the openings are communicated with the water inlet.

The electromagnetic valve upper body and the electromagnetic valve lower body separate the opening and the water outlet.

Further, the flow regulating component comprises a knob, the knob is fixedly connected with a screw rod, and the screw rod is in threaded fit with the screw sleeve.

The screw sleeve is a hollow stepped cylinder, the outer diameter of the upper cylinder is smaller, an internal thread is arranged, the outer diameter of the lower cylinder is larger, a larger empty chamber is formed in the lower cylinder, the upper cylinder extends downwards to form a section of empty chamber of the lower cylinder, an annular cavity is formed between the extending section of the upper cylinder and the lower cylinder, and a spring is arranged in the annular cavity.

Further, an interlayer is arranged at the upper part of the screw rod, a screw rod sealing ring is arranged in the interlayer, the screw rod and the screw sleeve are coated in the valve cover, and a movable allowance is arranged between the lower end face of the knob and the valve cover.

Further, a fixed sleeve is arranged at the upper opening of the lower body of the electromagnetic valve, which is close to the water inlet, the fixed sleeve is a Y-shaped sleeve, and the upper surface of the fixed sleeve is in contact with the diaphragm in the flow regulating component.

Further, the end of the knob switch is provided with a top plate, one end of the top plate is located at the circle center of the knob switch, the other end of the top plate is located at the outer circle of the knob switch, and a limiting block is arranged at the other end of the knob switch.

The knob switch mounting hole is provided with an opening into which a locking plate is inserted.

The utility model has the following gain effects:

The flow regulating component comprises a diaphragm structure above the water inlet of the irrigation valve, and the tightness of the spring can be regulated through the spring connection tightness regulating structure above the diaphragm structure, so that the pressure required by the diaphragm structure when the diaphragm structure is opened is changed, and further, the flow control is realized. The rotary switch is arranged at the connecting position of the upper body and the lower body of the electromagnetic valve, and can periodically open the pilot hole through manual rotation when the electromagnet cannot work to open the pilot hole, so that the pilot hole is opened, the irrigation valve is opened, the emergency capacity is strong, the reliability is good, and the maintenance is convenient. And be equipped with filter screen piece filtration aquatic granule great impurity in the pilot hole position department of diaphragm structure and can reduce the wearing and tearing of the inside important subassembly of irrigation valve, and dismantle conveniently.

Drawings

FIG. 1 is an assembled cross-sectional view of an irrigation valve of the present utility model.

Fig. 2 is a schematic view of the flow path of the water flow at the time of opening of the present utility model.

Fig. 3 is a schematic view of a rotary switch according to the present utility model.

In the figure, 1-knob, 2-screw, 3-screw sealing ring, 4-valve cover, 5-screw sleeve, 6-screw, 7-spring, 8-diaphragm, 9-fixed sleeve, 10-deflector, 11-diaphragm, 12-sealing gasket, 13-diaphragm locking gasket, 14-screw cap, 15-filter mesh, 16-electromagnetic head shell, 17-iron sheet, 18-coil skeleton, 19-power wire, 20-static iron core, 21-static iron core sealing ring, 22-iron sleeve, 23-enamelled copper wire, 24-iron core spring, 25-iron gasket, 26-movable iron core, 27-electromagnetic head sealing ring, 28-iron core sealing ring, 29-switch sealing ring, 30-knob switch, 31-locking plate, 32-valve seat, 33-water inlet, 34-water outlet, 35-knob switch mounting hole, 36-top plate and 37-limiting block.

Detailed Description

The utility model will be further described with reference to the drawings and the specific embodiments, but the scope of the utility model is not limited thereto.

Embodiment one:

As shown in fig. 1 to 3, the present utility model relates to an irrigation valve, which comprises an upper solenoid valve body and a lower solenoid valve body. The upper electromagnetic valve body and the flow regulating component are positioned above the lower electromagnetic valve body. The flow regulating member is mounted at a position near the middle of the lower body of the solenoid valve, and the upper body of the solenoid valve is mounted at a position near one side of the water outlet 34. In the present utility model, the solenoid valve upper body includes an electromagnet.

For the pilot type electromagnetic valve, the membrane structure of the pilot type electromagnetic valve is connected with the electromagnet in a more conventional mode, so that the electromagnet is positioned in the middle of the electromagnetic valve. In the present utility model, the diaphragm structure is connected to the flow regulating member so that the flow regulating member is located at the middle of the solenoid valve and the solenoid is located at the side end, and the upper body of the solenoid valve is installed closer to the water outlet 34 because water is required to flow from the water inlet 33 to the water outlet 34 along the pilot hole.

In the utility model, the flow regulating component can be divided into an upper part and a lower part, the upper part is of an tightness regulating structure and comprises a knob 1, a screw rod 2, a screw rod sealing ring 3 and a screw sleeve 5, the knob 1 is fixedly connected with the screw rod 2, and when the knob 1 rotates, the screw rod 2 can rotate at the same angular speed. The screw rod 2 is cylindric, and the upper end of screw rod 2 outwards extends there is two-layer great disc structure of diameter, installs screw rod sealing washer 3 in the below of disc structure in the middle of two-layer disc structure, is equipped with the screw thread along the outer wall of screw rod 2, and screw rod 2 upwards extends from the lower part and is equipped with a blind hole that the degree of depth is great.

The screw sleeve 5 is a hollow cylindrical sleeve, the screw sleeve 5 is a stepped column, the diameter of the upper column of the screw sleeve 5 is smaller, the diameter of the lower column of the screw sleeve 5 is larger, the cavity inside the screw sleeve 5 is larger, the upper column of the screw sleeve 5 also extends downwards to form a section, and because the outer diameter of the upper column is smaller than the inner diameter of the lower column of the screw sleeve 5, a gap exists between the extending section of the upper column and the lower column in the lower column, and the spring 7 can be installed due to the larger size of the gap. The diameter of the disk-like structure of the screw 2 is similar to the diameter of the upper column of the sleeve 5. During rotation, the screw 2 remains in position relatively stationary, while the sleeve 5 slides up and down on the screw 2.

The whole tightness adjusting structure is covered in the valve cover 4 except the knob 1, the disc-shaped structure of the screw rod 2 can limit the tightness adjusting structure, the tightness adjusting structure can be kept in the valve cover 4, a part of the valve cover 4, which is matched with the tightness adjusting structure, is provided with a corresponding stepped hole section, two steps are arranged at the part, which is matched with the tightness adjusting structure, in the valve cover 4, the steps at the upper end limit the movement of the disc-shaped structure, and the steps at the middle part limit the movement of the screw sleeve 5.

The lower part of the flow regulating member is a membrane structure comprising, from top to bottom, a baffle 10 and a membrane 8 and a membrane sheet 11 and a gasket 12 and a membrane locking washer 13 and a filter screen 15 and a screw cap 14. The diaphragm structure is formed by stacking various components. The baffle 10 is arranged at the uppermost layer, the middle part of the baffle 10 is a hollow cylinder, the hollow inside is in a structure with a large upper part, a narrow middle part and a widened lower part and a smaller diameter than the upper part. The shape of the transitional empty chamber between the upper large empty chamber and the middle small empty chamber is a ladder table shape, and the shape of the transitional empty chamber between the middle small empty chamber and the lower widened empty chamber is also a ladder table shape.

The section from the end of the upper large chamber to the end of the middle small chamber is positioned on the outer wall of the guide plate 10 to be outwards derived into a circular table-shaped disc structure, and the upper area of the disc structure is large, and the lower area of the disc structure is small. The diaphragm 11 is of a disc-shaped structure and is sleeved on the hollow cylinder of the guide plate 10, the diaphragm 11 is matched with the guide plate 10, and the circular table surface of the guide plate 10 is matched with the upper part of the diaphragm 11.

Thus, the upper portion of the diaphragm 11 is recessed inward by a portion, and the recessed portion is shaped to match the truncated cone shape of the baffle 10. Although the truncated cone portion of the baffle 10 mates with the concave portion of the diaphragm 11, the two are not in direct contact. The diaphragm 8 is fitted over the inner wall of the lowest point of the concave portion of the diaphragm 11, and the diaphragm 8 is sandwiched between the truncated cone portion of the baffle 10 and the concave portion of the diaphragm 11.

The sealing gasket 12 is sleeved on the hollow cylinder of the guide plate 10, the upper half part of the sealing gasket 12 is embedded in the lower half part of the diaphragm 11, the diameter of the sealing gasket 12 is larger than the upward outlet diameter of the water inlet 33, and the sealing gasket 12 covers the pipeline opening at the outlet of the water inlet 33.

The upper surface of the diaphragm locking gasket 13 is attached to the lower surface of the sealing gasket 12, the diaphragm locking gasket 13 is also sleeved on the hollow cylinder of the deflector 10, and threads are arranged on the outer wall of the hollow cylinder of the deflector 10 below the lower end surface of the diaphragm locking gasket 13. A filter screen 15 is attached to the lower end surface of the hollow cylinder of the deflector 10, a screw cap 14 is in threaded fit with the hollow cylinder of the lower end of the deflector 10, and the filter screen 15 is clamped between the screw cap 14 and the deflector 10. Because the diaphragm structure is integrated configuration, the clearance is convenient, and one of them part damages the change and also more convenient, maintains the repair simple.

The diaphragm structure is installed in the valve by clamping the outer edge of the diaphragm 8 through the valve cover 4 and the valve seat 32, and a fixing sleeve 9 is arranged below the installation position of the diaphragm 8 in the valve seat 32, wherein the fixing sleeve 9 is a Y-shaped sleeve. The upper part of the fixed sleeve 9 is clamped on the step of the inner wall of the valve seat 32, and the outer wall of the lower half part is attached to the inner wall of the valve seat 32. Because the membrane 8 is flexible, the shape can be changed, and thus a portion of the membrane 8 is attached to the upper surface of the fixing sleeve 9.

The diaphragm structure and the tightness adjusting structure are connected through a spring 7, one end of the spring 7 is sleeved in a gap between an extension section of an upper column and a lower column of the screw sleeve 5, and because of the characteristic of the pilot valve, the diaphragm structure is lifted to enable the water inlet 33 and the water outlet 34 to be communicated without depending on the tensile force of the spring 7, but the diaphragm structure closes a flow path between the water inlet 33 and the water outlet 34 on one hand depending on the gravity of the diaphragm structure and on the other hand depending on the additional downward pressure applied to the diaphragm structure by the spring.

Therefore, the lower end of the spring 7 is sleeved on the outer wall of the hollow cylinder at the upper part of the guide plate 10, and the upper end of the spring 7 is clamped in a gap between the extension section of the upper column of the screw sleeve 5 and the lower column, so that the spring 7 is ensured not to fall out between the tightness adjusting structure and the diaphragm structure. The screw rod 2 can be rotated by rotating the knob 1 to enable the screw sleeve 5 to move downwards, so that the spring 7 is compressed, the downward pressure applied to the diaphragm structure by the spring is increased, and the force of water for jacking the diaphragm structure against the gravity of the diaphragm structure and the pressure of the spring is increased. Thereby reducing the flow from the water inlet 33 to the water outlet 34.

The electromagnet assembly is located beside the tightness adjusting structure and is fixed on the valve cover 4 through screw threads in a rotating manner, the iron core sealing ring 28 of the electromagnet covers a pilot hole on the valve seat 32 leading to the water outlet 34, and only when the electromagnet is electrified, the movable iron core 26 moves upwards to open the pilot hole covered by the iron core sealing ring 28, so that water flow can flow along the pilot hole to generate pressure difference. And then jack up the diaphragm structure to allow water flow directly from the water inlet 33 to the water outlet 34.

Embodiment two:

An electromagnetic valve upper body structure is arranged near the tightness adjusting structure and comprises an electromagnet assembly. The periphery of the electromagnet is covered by an electromagnetic head shell 16, a cavity is formed in the electromagnetic head shell, enamelled copper wires 23 are placed on two sides of the cavity, a layer of coil framework 18 is further covered on the outer layer of the enamelled copper wires, an iron sheet 17 is further arranged above the coil framework 18, the iron sheet 17 is clamped between the coil framework 18 and the electromagnetic head shell 16, and an iron sleeve 22 is further arranged on the outer side of the coil framework 18 and is clamped between the coil framework 18 and the electromagnetic head shell 16. An iron washer 25 is provided between the bobbin 18 and the electromagnetic head 16 at the inner side and the lower side of the bobbin 18.

A cavity is provided in the middle of the coil bobbin 18 to house the core assembly. The top is a static iron core 20, the static iron core 20 is fixed in the electromagnetic head shell 16, and a static iron core sealing ring 21 is arranged between the static iron core 20 and the coil skeleton 18. A movable iron core 26 is arranged below the static iron core 21, and the static iron core 21 and the movable iron core 26 are connected through an iron core spring 24. The bottom of the movable iron core 26 is covered with an iron core sealing ring 28, and the outer part of the iron core sealing ring 28, which is exposed out of the opening of the electromagnetic head shell 16, is blocked above the pilot hole of the valve seat 32.

The lower end of the electromagnetic head shell 16 is matched and installed with the valve cover 4 through threads, and an electromagnetic head sealing ring 27 is embedded into the bottom end face of the electromagnetic head shell 16. The top of the electromagnetic head 16 is connected with a power line 19.

The present embodiment differs from the first embodiment in that a knob switch mounting hole 35 is provided between the valve cover 4 and the valve seat 32 on the outside on the side where the electromagnet is mounted, for mounting the knob switch 30. The knob switch 30 is provided with a switch sealing ring 29 at a position where it contacts the inner wall of the valve cap 4 and the valve seat 32. The end of the knob switch 30 is provided with a top plate 36, one end of the top plate 36 is positioned at the center of the knob switch 30, the other end of the top plate is positioned at the outer circle of the knob switch 30, and the other end of the knob switch is provided with a limiting block 37. The knob switch mounting hole 35 is provided with an opening into which the locking piece 31 is inserted. The opening is located at the valve seat 32. The stopper 37 may restrict the angle by which the knob switch 30 rotates in the knob switch mounting hole 35.

The top plate 36 of the general knob switch 30 is not in contact with the bottom of the iron core sealing ring 28, so that the normal work of the electromagnet is not affected, but when the electromagnet is powered off or fails, the pilot hole cannot be normally opened to open the irrigation valve. Knob switch 30 can be rotated to raise plunger 26 using top plate 36 to open the pilot hole and thereby open the irrigation valve. When the irrigation valve is closed, the knob switch 30 is only required to be rotated to be separated from contact with the iron core sealing ring 28 of the movable iron core 26, and the movable iron core can also block the pilot hole under the action of gravity, so that the irrigation valve is closed. The valve cover 4 and the valve seat 32 are fixedly connected through a screw 6.

Embodiment III:

This embodiment describes how the irrigation valve opens and closes and how it flows between the water pilot holes.

As shown in fig. 2, before the electromagnet is turned on, water cannot flow in because a closed structure is formed between the membrane structure and the tightness adjusting structure. After the electromagnet is switched on, water flows in from the water inlet 33, and at this time, because the diaphragm structure blocks the water outlet, water can only flow between the diaphragm structure and the tightness adjusting structure from the middle hole position of the deflector 10. The valve cap 4 and the valve seat 32 have a flow path between the dancer structure and the electromagnet structure, into which water can flow, and a pilot hole of the electromagnet position is opened due to the movable iron core 26 being attracted, and water flows from the pilot hole to the water outlet 34. A flow path is formed for the water flow from the water inlet 33 to the water outlet 34.

Because the water between the diaphragm structure and the dancer structure is flowing, the pressure is reduced, the diaphragm structure is lifted, and the water flow directly flows from the water inlet 33 to the water outlet 34, thereby completing the opening of the irrigation valve.

The closing of the irrigation valve only requires the electromagnet to be de-energized, at this time, the plunger 26 falls under the action of gravity, re-blocking the pilot hole, at this time the upper flow path is blocked, but the water below is still flowing, the upper pressure is greater than below, and the diaphragm structure is pressed downward to block the upper opening of the water inlet 33, thereby closing the irrigation valve.

It should be noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present utility model, and not for limiting the same, and although the present utility model has been described in detail with reference to the above-mentioned embodiments, it should be understood by those skilled in the art that the technical solution described in the above-mentioned embodiments may be modified or some technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiments of the present utility model.

Claims

1. An irrigation valve comprises an upper electromagnetic valve body and a lower electromagnetic valve body, and is characterized in that a flow regulating component is arranged above a water inlet (33) of the irrigation valve, and an upper electromagnetic valve body is arranged above a water outlet (34) of the irrigation valve;

the connection position of the upper electromagnetic valve body and the lower electromagnetic valve body is provided with a knob switch mounting hole (35), and the knob switch (30) is mounted in the knob switch mounting hole (35).

2. The irrigation valve as recited in claim 1, wherein the flow regulating member comprises a slack adjuster structure and a diaphragm structure, a spring (7) is connected between the slack adjuster structure and the diaphragm structure, the diaphragm structure comprises a deflector (10) and a diaphragm (11) for sandwiching the diaphragm (8), a hollow cylinder protrudes upward and downward from the middle of the deflector (10), and threads are provided on the outer side of the hollow cylinder below.

3. The irrigation valve according to claim 2, wherein the hollow cylinder of the deflector (10) is sleeved with a diaphragm (11), a sealing gasket (12) and a diaphragm locking gasket (13) from top to bottom, the sealing gasket (12) is semi-embedded in the diaphragm (11), and the upper surface of the diaphragm locking gasket (13) is in contact with the lower surface of the sealing gasket (12);

a screw cap (14) is screwed at the thread of the hollow cylinder of the guide plate (10), and a filter screen (15) is arranged between the screw cap (14) and the opening of the hollow cylinder.

4. Irrigation valve according to claim 1, wherein the inlet opening (33) is directed upwards at the opening of the lower body of the solenoid valve, contacting the lower end surface of the gasket (12) below the flow regulating member, the inlet opening (33) and the outlet opening (34) being at the same level with the axis, a valve wall being provided between the inlet opening (33) and the outlet opening (34) at a position close to the outlet opening (34) separating the two.

5. An irrigation valve as in claim 1 or 2 or 3 or 4, wherein the flow regulating member and the lower body of the solenoid valve are provided with an opening at a position close to the water outlet (34), the opening being in communication with the water inlet (33);

The solenoid valve upper body and the solenoid valve lower body block the opening and the water outlet (34).

6. The irrigation valve according to claim 1 or 2 or 3 or 4, wherein the flow regulating member comprises a knob (1), the knob (1) being fixedly connected to a screw (2), the screw (2) being in threaded engagement with a threaded sleeve (5);

The screw sleeve (5) is a hollow stepped cylinder, the outer diameter of the upper cylinder is smaller, an internal thread is arranged, the outer diameter of the lower cylinder is larger, a larger empty chamber is arranged in the lower cylinder, the upper cylinder extends downwards to form a section of empty chamber of the lower cylinder, an annular cavity is arranged between the extending section of the upper cylinder and the lower cylinder, and a spring (7) is arranged in the annular cavity.

7. The irrigation valve as recited in claim 6, wherein an upper portion of the screw (2) is provided with an interlayer, a screw sealing ring (3) is provided in the interlayer, the screw (2) and the screw sleeve (5) are wrapped in a valve cover (4), and a movable allowance is provided between a lower end face of the knob (1) and the valve cover.

8. The irrigation valve as recited in claim 1, 2, 3, 4 or 7, wherein a fixing sleeve (9) is arranged at an upper opening of the lower body of the electromagnetic valve, which is close to the water inlet (33), the fixing sleeve (9) is a Y-shaped sleeve, and an upper surface of the fixing sleeve (9) is in contact with the diaphragm (8) in the flow regulating component.

9. The irrigation valve as recited in claim 1 or 2 or 3 or 4 or 7, wherein a top plate (36) is arranged at the tail end of the knob switch (30), one end of the top plate (36) is positioned at the center of the knob switch (30), the other end of the top plate is positioned at the outer circle of the knob switch (30), and a limiting block (37) is arranged at the other end of the knob switch;

the knob switch mounting hole (35) is provided with an opening into which a locking plate (31) is inserted.