Cleaning structure for milk pipeline of coffee machine

Abstract

The utility model discloses a cleaning structure of a milk pipeline of a coffee machine, which comprises a mounting frame, a milk inlet part and a milk outlet part communicated with the milk inlet part are arranged on the mounting frame, a milk inlet unit and a milk outlet unit are respectively arranged on the milk inlet part and the milk outlet part, and a water inlet part used for feeding cleaning water flow is communicated with the milk inlet part. The milk outlet part is further provided with an extrusion unit matched with the milk outlet unit, cleaning water flow enters the milk inlet part from the water inlet part, and when the extrusion unit extrudes the milk outlet unit, the sectional area of the inner hole diameter of the milk outlet unit is reduced till the sectional area of the inner hole diameter of the milk outlet unit is reduced to be approximate to the sectional area of the inner hole diameter of the milk inlet unit. The pressure in the milk inlet part is close to the pressure in the milk outlet part, and the cleaning water flow is discharged from the milk inlet unit and the milk outlet unit at the same time, so that the effect of cleaning the interior of the milk inlet part and the interior of the milk outlet part at the same time is achieved. According to the utility model, through the extrusion effect of the extrusion unit on the milk outlet pipe, the sectional area of the internal aperture of the milk outlet pipe is reduced, and internal clean water is discharged from the milk inlet pipe and the milk outlet pipe at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to coffee machine field especially, it is a kind of cleaning structure of coffee machine milk pipe line. BACKGROUND

[0002] With the spread of coffee culture, coffee has been integrated into the life of ordinary people, and various coffee machines have entered the homes of ordinary citizens in large quantities. With the popularity of household coffee machines, many people are keen on making coffee at home. Since pure coffee is very bitter, many people like to use coffee with milk, and the coffee with milk is smoother and more delicious. In addition to the rich coffee aroma, there is also a faint milk fragrance. Scientifically proven, drinking the right amount of coffee milk every day is good for the heart and brain.

[0003] The milk pipe line in the coffee machine will have some milk remaining in the pipe line after each use, which will cause deterioration and scaling over a long period of time, so it needs to be cleaned in time. When cleaning, cleaning water is usually introduced into the milk frother, but since the cross-sectional area of the milk outlet pipe is usually larger than that of the milk suction hole, the internal and external air pressure difference cannot discharge the cleaning water inside, so the pipe line and hole inside the milk inlet and outlet cannot be washed in all directions, which will cause deterioration and scaling over a long period of time, affecting health. SUMMARY

[0004] The utility model provides a kind of cleaning structure of coffee machine milk pipe line to solve the technical problems of prior art.

[0005] The utility model provides a kind of cleaning structure of coffee machine milk pipe line to solve the technical problems of prior art.

[0006] Preferably, the milk inlet portion includes an upper shell and a lower shell connected to each other, the milk inlet unit includes a milk inlet pipe arranged at the bottom of the lower shell, the milk inlet portion is provided with a milk passing channel and a cavity, the milk inlet pipe is communicated with the milk passing channel through a milk suction hole, and the milk passing channel is communicated with the cavity through a milk outlet hole.

[0007] Preferably, the milk outlet unit comprises a milk outlet pipe, the lower shell extends towards the milk outlet part and is provided with a milk outlet nozzle, the milk outlet nozzle is in communication with the inside of the cavity, the milk outlet pipe is connected with the milk outlet nozzle, and the milk outlet pipe is in communication with the inside of the cavity through the milk outlet nozzle.

[0008] Preferably, the extrusion unit is arranged on the mounting frame, the extrusion unit comprises a motor, a cam is connected to the output shaft of the motor, the cam is provided with a protruding part for extruding the outer wall of the milk outlet pipe, the motor drives the rotation of the cam, the protruding part extrudes the outer wall of the milk outlet pipe, and the inside hole diameter of the milk outlet pipe is reduced.

[0009] Preferably, the hole diameter of the milk suction hole is smaller than the hole diameter of the milk outlet hole, the milk inlet pipe is externally connected with a milk suction pipe; the milk inlet part comprises a steam pipe arranged on the upper shell, and the upper shell is further provided with an air pipe for introducing air, the inside of the air pipe and the inside of the steam pipe are both in communication with the milk passage, the steam pipe introduces steam into the milk inlet part during the process of making milk foam, and when cleaning is needed, the temperature is reduced, and the steam pipe introduces cleaning hot water into the milk inlet part.

[0010] Preferably, the milk outlet pipe is connected with a connecting pipe, the connecting pipe is provided with a protruding part protruding towards the extrusion unit, and the inside of the protruding part is a moving cavity for moving the extrusion unit; a through hole is arranged in the connecting pipe for the extrusion unit to pass through, the through hole is in communication with the inside of the connecting pipe and the moving cavity, and the extrusion unit extends into the inside of the connecting pipe through the through hole.

[0011] Preferably, one end of the extrusion unit is connected with a driving unit for driving the movement of the extrusion unit, the other end of the extrusion unit extends into the inside of the connecting pipe, the extrusion unit comprises a push rod and a plug arranged at the front end of the push rod, and the end of the push rod away from the plug is loosely connected with the driving unit; a sealing ring is sleeved on the push rod, the sealing ring moves synchronously with the push rod, and the inner wall of the moving cavity is provided with a first inclined surface and a second inclined surface in abutting cooperation with the sealing ring.

[0012] Preferably, the driving unit comprises an electromagnet, an output rod is connected to the electromagnet, the output rod is loosely connected with the push rod, and a small force applied by the electromagnet can drive the push rod to move through the output rod, so that the plug extends into the inside of the extrusion connecting pipe, until the cross-sectional area of the inside hole of the connecting pipe is reduced to be approximately equal to the cross-sectional area of the hole diameter of the milk suction hole.

[0013] Preferably, a spring is sleeved on the push rod, the spring is arranged outside the protruding part, one end of the spring is in abutting connection with the outer wall of the protruding part, and the other end of the spring is in abutting connection with the push rod.

[0014] Compared with the prior art, the utility model has the advantages that: through the extrusion unit to the milk outlet pipe extrusion effect, make the milk outlet pipe internal aperture section area reduce, reduce to with the milk hole internal aperture section area is approximate, the pressure in the milk inlet portion and the pressure in the milk outlet portion are close, enough to clean the water in the milk frother inside from the milk inlet pipe and the milk outlet pipe to the outside, reach the effect of cleaning the milk inlet portion and the milk outlet portion simultaneously, so that when cleaning, it is not necessary to operate too much additionally, can complete the cleaning of the milk outlet pipe and the milk inlet pipe, no matter the highest water level of the milk suction pipe external pipeline is higher than or lower than the milk frother, water can be discharged to achieve the cleaning effect. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 It is the structure schematic diagram of the utility model;

[0016] Fig. 2 It is the section structure schematic diagram of the utility model;

[0017] Fig. 3 It is the section structure schematic diagram of the utility model;

[0018] Fig. 4 It is the structure schematic diagram of embodiment 2 of the utility model;

[0019] Fig. 5 It is the section structure schematic diagram of the utility model embodiment 2 electromagnet power-off state;

[0020] Fig. 6 It is the section structure schematic diagram of the utility model embodiment 2 electromagnet power-on state.

[0021] Fig. 1, milk inlet portion; 2, milk outlet portion; 3, upper shell; 4, lower shell; 5, milk inlet pipe; 6, milk passage; 7, cavity; 8, milk suction hole; 9, milk outlet hole; 10, milk outlet pipe; 11, milk outlet nozzle; 12, mounting frame; 13, motor; 14, cam; 15, convex part; 16, milk suction pipe; 17, air pipe; 18, steam pipe; 19, connecting pipe; 20, convex piece; 21, moving cavity; 22, through hole; 23, push rod; 24, plug; 25, sealing ring; 26, first inclined surface; 27, second inclined surface; 28, electromagnet; 29, output rod; 30, spring. DETAILED DESCRIPTION

[0022] In the following, multiple embodiments of the utility model will be disclosed by means of drawings. For the purpose of clear illustration, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit the utility model. That is, in some embodiments of the utility model, these practical details are unnecessary. In addition, for the purpose of simplifying the drawings, some conventional structures and components will be shown in a simple schematic manner in the drawings.

[0023] It should be noted that all directional indications, such as upper, lower, left, right, front, back, etc. in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0024] In addition, in addition to being used to represent the orientation or positional relationship, the above-mentioned terms can also be used to represent other meanings, for example, the term "upper" can also be used to represent a certain dependent relationship or connection relationship in some cases, and those skilled in the art can understand the specific meaning of these terms in the present application according to the specific circumstances.

[0025] In addition, the terms "mounting", "setting", "providing", "connecting", "connecting", "sleeving" should be understood broadly. For example, it can be fixedly connected, detachably connected, or integrally configured; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, or it can be the internal communication between two devices, elements or components. The connection mode involved in the present application is prior art and does not have any improvement, and belongs to the common knowledge of those skilled in the art. Those skilled in the art can understand the specific meaning of the above-mentioned terms in the present application according to the specific circumstances.

[0026] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and does not mean to specially indicate the order or sequence, nor to limit the present application. It is only used to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application. Example 1

[0027] As Figs. 1 to 3The utility model provides a kind of cleaning structure of milk pipe line, including mounting bracket 12, mounting bracket 12 is equipped with milk inlet portion 1 and with the milk outlet portion 2 of milk inlet portion 1 communication, milk inlet portion 1 and milk outlet portion 2 are equipped with milk inlet unit and milk outlet unit respectively, milk inlet portion 1 is equipped with water inlet portion for entering cleaning water flow communication;Specifically, the milk outlet portion 2 is also equipped with extrusion unit matched with milk outlet unit, cleaning water flow enters milk inlet portion 1 from water inlet portion, when extrusion unit extrudes milk outlet unit, the cross-sectional area of internal aperture of milk outlet unit reduces, until the cross-sectional area of internal aperture of milk outlet unit reduces to be similar with the cross-sectional area of internal aperture of milk inlet unit, the pressure inside milk inlet portion 1 and the pressure inside milk outlet portion 2 are close, cleaning water flow is discharged from milk inlet unit and milk outlet unit simultaneously, reach the effect of cleaning milk inlet portion 1 inside and milk outlet portion 2 inside simultaneously.

[0028] The milk inlet portion 1 includes upper shell 3 and lower shell 4 connected with each other, and the milk inlet unit includes a milk inlet pipe 5 arranged at the bottom of the lower shell 4. The milk inlet portion 1 is provided with a milk passing channel 6 and a cavity 7. Specifically, the milk inlet pipe 5 is communicated with the milk passing channel 6 through a milk suction hole 8, and the milk passing channel 6 is communicated with the cavity 7 through a milk outlet hole 9.

[0029] The milk outlet unit includes a milk outlet pipe 10, and the lower shell 4 extends to the milk outlet portion 2 and is provided with a milk outlet nozzle 11. Specifically, the milk outlet nozzle 11 is communicated with the inside of the cavity 7, the milk outlet pipe 10 is connected with the milk outlet nozzle 11, and the milk outlet pipe 10 is communicated with the inside of the cavity 7 through the milk outlet nozzle 11.

[0030] The extrusion unit is arranged on the mounting bracket 12, and the extrusion unit includes a motor 13. A cam 14 is connected to the output shaft of the motor 13. Specifically, the cam 14 is provided with a protruding portion 15 for extruding the outer wall of the milk outlet pipe 10. The motor 13 drives the cam 14 to rotate, the protruding portion 15 extrudes the outer wall of the milk outlet pipe 10, and the cross-sectional area of the internal aperture of the milk outlet pipe 10 is reduced.

[0031] The diameter of the milk suction hole 8 is smaller than the diameter of the milk outlet hole 9, and the milk inlet pipe 5 is connected with a milk suction pipe 16. Specifically, the water inlet portion includes a steam pipe 18 arranged on the upper shell 3. The upper shell 3 is also provided with an air pipe 17 for introducing air. The inside of the air pipe 17 and the inside of the steam pipe 18 are both communicated with the milk passing channel 6. The steam pipe 18 introduces steam into the milk inlet portion 1 during milk frothing. When cleaning is needed, the temperature is reduced, and the steam pipe 18 introduces cleaning hot water into the milk inlet portion 1. The steam pipe 18 is communicated with an external boiler.

[0032] The working principle of the embodiment is that: in the process of making milk foam, the high-speed sprayed steam enters the milk passage 6 through the steam pipe 18, and then enters the cavity 7 through the milk outlet hole 9, so that the inside of the milk frother is filled with steam, a negative pressure is formed in the inside of the milk frother, the milk is sucked into the cavity 7 from the milk inlet pipe 5, and the air pipe 17 simultaneously pressurizes the outside air into the milk frother, so that the air is mixed into the milk to form a foaming state, and the foamed milk is then discharged through the milk outlet pipe 10;

[0033] When the inside of the milk frother needs to be cleaned, the temperature in the steam pipe 18 is reduced, the cleaning hot water in the boiler enters the inside of the milk inlet part 1 through the steam pipe 18, and because the pipe diameter cross-sectional area of the milk outlet pipe 10 is usually larger than that of the milk suction hole 8, the internal and external air pressure difference cannot discharge the cleaning water inside, at this time, the user can start the motor 13, the output shaft of the motor 13 drives the cam 14 to rotate, and the protruding part 15 extrudes the outer wall of the milk outlet pipe 10 in the rotating process, so that the internal hole diameter cross-sectional area of the milk outlet pipe 10 is reduced, until the internal hole diameter cross-sectional area of the milk outlet pipe 10 is reduced to be similar to that of the milk suction hole 8, the pressure inside the milk inlet part 1 is close to that inside the milk outlet part 2, and the cleaning water flow is discharged from the milk inlet pipe 5 and the milk outlet pipe 10 at the same time, achieving the effect of simultaneously cleaning the inside of the milk inlet part 1 and the inside of the milk outlet part 2.

[0034] The advantage of the embodiment is that: through the extrusion of the extrusion unit on the milk outlet pipe 10, the internal hole diameter cross-sectional area of the milk outlet pipe 10 is reduced, and is reduced to be similar to that of the milk suction hole 8, the pressure inside the milk frother is greater than the external pressure, which is sufficient to discharge the cleaning water inside the milk frother from the milk inlet pipe 5 and the milk outlet pipe 10 to the outside at the same time, achieving the effect of simultaneously cleaning the inside of the milk inlet part 1 and the inside of the milk outlet part 2, so that no additional operation is required during cleaning, and the cleaning of the milk outlet pipe 10 and the milk inlet pipe 5 can be completed, and the water can be discharged to achieve the cleaning effect regardless of whether the highest water level of the milk suction pipe 16 external pipeline is higher or lower than the milk frother. Embodiment 2

[0035] As shown in Figs. 4 to 6 different from embodiment 1, in the embodiment, the milk outlet pipe 10 is connected with a connecting pipe 19, the connecting pipe 19 is provided with a protruding part 20 protruding towards the extrusion unit, and the inside of the protruding part 20 is a moving cavity 21 for moving the extrusion unit; specifically, the connecting pipe 19 is provided with a through hole 22 for the extrusion unit to pass through, the through hole 22 communicates the inside of the connecting pipe 19 and the moving cavity 21, and the extrusion unit extends into the inside of the connecting pipe 19 through the through hole 22.

[0036] The extrusion unit is connected with a driving unit at one end for driving the movement of the extrusion unit, the other end of the extrusion unit extends into the inside of the connecting pipe 19, the extrusion unit comprises a push rod 23 and a plug 24 arranged at the front end of the push rod 23, the end of the push rod 23 away from the plug 24 is loosely connected to the driving unit; specifically, a sealing ring 25 is sleeved on the push rod 23, the sealing ring 25 moves synchronously with the push rod 23, and the inner wall of the moving cavity 21 is provided with a first inclined surface 26 and a second inclined surface 27 in abutting cooperation with the sealing ring 25.

[0037] The driving unit comprises an electromagnet 28, the electromagnet 28 is connected with an output rod 29, the output rod 29 is loosely connected with the push rod 23; specifically, the electromagnet 28 can push the push rod 23 to move through the output rod 29 by exerting a small force, so that the plug 24 extends into the inside of the extrusion connecting pipe 19, until the cross-sectional area of the inside hole of the connecting pipe 19 is reduced to be approximately equal to the cross-sectional area of the milk suction hole 8.

[0038] The push rod 23 is sleeved with a spring 30, the spring 30 is arranged outside the protruding piece 20, one end of the spring 30 is in abutting connection with the outer wall of the protruding piece 20, and the other end of the spring 30 is in abutting connection with the push rod 23. The other structures are the same as those in Embodiment 1.

[0039] The working principle of the embodiment is as follows: in the de-energized state of the electromagnet 28, the plug 24 does not extend into the connecting pipe 19, the plug 24 is located in the through hole 22, the sealing ring 25 on the push rod 23 is in abutting connection with the second inclined surface 27, so that the milk discharged in the process of making milk foam is prevented from leaking out of the moving cavity 21 to the outside, and the spring 30 is in a relaxed state;

[0040] When the milk foam making is completed and the inside of the milk foaming device needs to be cleaned, the temperature in the steam pipe 18 is reduced, the cleaning hot water in the boiler enters the inside of the milk inlet part 1 through the steam pipe 18, the electromagnet 28 is started, in the energized state of the electromagnet 28, the output rod 29 on the electromagnet 28 pushes the push rod 23 and the plug 24 to move in the direction of the connecting pipe 19, since the push rod 23 and the output rod 29 are loosely connected, the electromagnet 28 only needs a small force to push the push rod 23, does not need to bear additional resistance, and only needs to use a small size electromagnet 28 to achieve the purpose; the plug 24 gradually extends into the inside of the connecting pipe 19, the spring 30 is compressed, the cross-sectional area of the inside hole of the connecting pipe 19 is gradually reduced, until the sealing ring 25 on the push rod 23 is in abutting connection with the first inclined surface 26, the cross-sectional area of the inside hole of the connecting pipe 19 is reduced to be approximately equal to the cross-sectional area of the milk suction hole 8, the pressure in the inside of the milk inlet part 1 is close to the pressure in the inside of the milk outlet part 2, and the cleaning water flow is discharged from the milk inlet pipe 5 and the milk outlet pipe 10 at the same time, so that the inside of the milk inlet part 1 and the inside of the milk outlet part 2 are cleaned at the same time.

[0041] The advantage of the embodiment is that the extrusion of the pipe unit by the extrusion unit reduces the sectional area of the internal hole of the connecting pipe 19, the electromagnet 28 only needs a small force to push the push rod 23, does not need to bear additional resistance, and only needs to use a small size electromagnet 28 to achieve.

[0042] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0043] The standard parts used in the present application can be purchased from the market, and the special-shaped parts can be ordered according to the description and drawings. The specific connection mode of each part adopts the conventional means of mature bolt, rivet, welding, sticking and the like in the prior art, which will not be described in detail here.

[0044] The above is only the preferred embodiment of the present application, and for those skilled in the art, according to the idea of the present application, various modifications and changes can be made in the specific implementation mode and application range, and the content of the present specification should not be understood as the limitation of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the scope of the claims of the present application.

Claims

1. A cleaning structure of a milk pipe of a coffee machine, comprising a mounting frame, a milk inlet portion and a milk outlet portion in communication with the milk inlet portion are arranged on the mounting frame, a milk inlet unit and a milk outlet unit are respectively arranged on the milk inlet portion and the milk outlet portion, and a water inlet portion for inletting a cleaning water flow is arranged in communication on the milk inlet portion, characterized in that: The milk outlet part is further provided with a squeezing unit matched with the milk outlet unit. The cleaning water flows into the milk inlet part from the water inlet part. When the squeezing unit squeezes the milk outlet unit, the cross-sectional area of the internal aperture of the milk outlet unit is reduced until the cross-sectional area of the internal aperture of the milk outlet unit is similar to that of the milk inlet unit. The pressure inside the milk inlet part is close to that inside the milk outlet part. The cleaning water is discharged from the milk inlet unit and the milk outlet unit at the same time, achieving the effect of simultaneously cleaning the inside of the milk inlet part and the milk outlet part.

2. The milk line cleaning structure according to claim 1, characterized in that: The milk inlet part comprises an upper shell and a lower shell connected with each other. The milk inlet unit comprises a milk inlet pipe arranged at the bottom of the lower shell. The milk inlet part is internally provided with a milk passing channel and a cavity. The milk inlet pipe is communicated with the milk passing channel through a milk suction hole. The milk passing channel is communicated with the cavity through a milk outlet hole.

3. A milk line cleaning arrangement according to claim 2, characterised in that: The milk outlet unit comprises a milk outlet pipe. The lower shell extends towards the milk outlet part and is provided with a milk outlet nozzle. The milk outlet nozzle is communicated with the inside of the cavity. The milk outlet pipe is connected with the milk outlet nozzle. The milk outlet pipe is communicated with the inside of the cavity through the milk outlet nozzle.

4. The milk line cleaning structure according to claim 3, characterized in that: The squeezing unit is arranged on the mounting frame. The squeezing unit comprises a motor. A cam is connected with the output shaft of the motor. The cam is provided with a protruding part for squeezing the outer wall of the milk outlet pipe. The motor drives the rotation of the cam. The protruding part squeezes the outer wall of the milk outlet pipe, and the cross-sectional area of the internal aperture of the milk outlet pipe is reduced.

5. The milk line cleaning structure according to claim 2, characterized in that: The aperture of the milk suction hole is smaller than that of the milk outlet hole. The milk inlet pipe is externally connected with a milk suction pipe. The water inlet part comprises a steam pipe arranged on the upper shell. The upper shell is further provided with an air pipe for air. The inside of the air pipe and the inside of the steam pipe are both communicated with the milk passing channel. The steam pipe is used for introducing steam into the milk inlet part during the process of milk frothing. When cleaning is needed, the temperature is reduced. The steam pipe is used for introducing cleaning hot water into the milk inlet part.

6. The milk line cleaning structure according to claim 3, characterized in that: The milk outlet pipe is connected with a connecting pipe. The connecting pipe is provided with a protruding part protruding towards the squeezing unit. The inside of the protruding part is a moving cavity for moving the squeezing unit. The connecting pipe is internally provided with a through hole for the squeezing unit to pass through. The through hole is communicated with the inside of the connecting pipe and the moving cavity. The squeezing unit extends into the inside of the connecting pipe through the through hole.

7. A milk line cleaning arrangement according to claim 6, characterised in that: One end of the squeezing unit is connected with a driving unit for driving the movement of the squeezing unit. The other end of the squeezing unit extends into the inside of the connecting pipe. The squeezing unit comprises a push rod and a plug arranged at the front end of the push rod. The end of the push rod away from the plug is loosely connected with the driving unit. A sealing ring is sleeved on the push rod. The sealing ring moves synchronously with the push rod. The inner wall of the moving cavity is provided with a first inclined surface and a second inclined surface in abutting cooperation with the sealing ring.

8. A milk line cleaning arrangement according to claim 7, characterised in that: The driving unit comprises an electromagnet. An output rod is connected with the electromagnet. The output rod is loosely connected with the push rod. A small force applied by the electromagnet can drive the push rod to move through the output rod. The plug extends into the inside of the squeezing connecting pipe until the cross-sectional area of the internal aperture of the connecting pipe is similar to that of the milk suction hole.

9. The milk line cleaning structure according to claim 7, characterized in that: A spring is sleeved on the push rod. The spring is arranged outside the protruding part. One end of the spring is in abutting connection with the outer wall of the protruding part. The other end of the spring is in abutting connection with the push rod.

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