Cleaning structure for milk circuit of coffee machine
By designing a squeezing unit in the milk hose of the coffee machine to reduce the diameter of the milk outlet, the problem of incomplete milk hose cleaning is solved, and the milk inlet and outlet are cleaned simultaneously, ensuring the cleaning effect.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NINGBO SEAVER ELECTRIC APPLIANCE
- Filing Date
- 2025-01-03
- Publication Date
- 2026-07-02
AI Technical Summary
Coffee machine milk hoses are difficult to clean completely after use, leading to milk residue, spoilage, and scale buildup, which can affect health.
A cleaning structure for the milk hose of a coffee machine is designed. By reducing the internal diameter of the milk outlet hose through a squeezing unit, the cleaning water pressure is made greater than the external pressure, thereby achieving simultaneous cleaning of the milk inlet and outlet sections.
It enables comprehensive cleaning of the milk hoses and pipes in coffee machines, preventing milk residue from spoiling and forming scale, and simplifying the cleaning process.
Smart Images
Figure CN2024142593_02072026_PF_FP_ABST
Abstract
Description
A cleaning structure for the milk hose of a coffee machine Technical Field
[0001] This utility model relates to the field of coffee machines, and in particular to a cleaning structure for the milk hose of a coffee machine. Background Technology
[0002] With the spread of coffee culture, coffee has become integrated into the lives of ordinary people, and various coffee machines have entered many ordinary households. With the popularity of home coffee machines, many people are keen to make coffee at home. Because pure coffee is very bitter, many people like to add milk to enhance its flavor. Coffee with milk is smoother and more palatable, and in addition to the rich coffee aroma, it also has a subtle milky fragrance. Scientific evidence shows that drinking a moderate amount of coffee with milk daily is beneficial to the heart and brain.
[0003] After each use, some milk residue remains in the milk tubing of a coffee machine. Over time, this can lead to spoilage and scale buildup, requiring timely cleaning. Cleaning typically involves introducing cleaning water into the milk frother. However, because the cross-sectional area of the milk outlet tube is usually larger than that of the milk suction hole, the pressure difference between the inside and outside prevents the cleaning water from being expelled. This prevents a thorough cleaning of the milk inlet and outlet tubes and holes, leading to spoilage and scale buildup over time, which can negatively impact health. Utility Model Content
[0004] The technical problem to be solved by this utility model is to provide a cleaning structure for the milk hose of a coffee machine, based on the current state of the technology.
[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a cleaning structure for the milk hose of a coffee machine, including a mounting bracket, a milk inlet and a milk outlet connected to the milk inlet, a milk inlet unit and a milk outlet unit respectively provided on the milk inlet and the milk outlet, a water inlet for introducing cleaning water connected to the milk inlet, and a squeezing unit cooperating with the milk outlet unit on the milk outlet. The cleaning water enters the milk inlet from the water inlet. When the squeezing unit squeezes the milk outlet unit, the cross-sectional area of the internal aperture of the milk outlet unit decreases until the cross-sectional area of the internal aperture of the milk outlet unit is reduced to be approximately the same as the cross-sectional area of the internal aperture of the milk inlet unit. The pressure inside the milk inlet is greater than the external pressure, and the cleaning water is discharged from the milk inlet unit and the milk outlet unit at the same time, achieving the effect of cleaning the inside of the milk inlet and the milk outlet unit at the same time.
[0006] Preferably, the milk inlet includes an upper shell and a lower shell connected to each other, the milk inlet unit includes a milk inlet pipe located at the bottom of the lower shell, the milk inlet is provided with a milk passage and a cavity, the milk inlet pipe is connected to the milk passage through a milk suction hole, and the milk passage is connected to the cavity through a milk outlet hole.
[0007] Preferably, the milk dispensing unit includes a milk dispensing tube, and a milk dispensing nozzle is provided on the lower shell extending towards the milk dispensing section. The milk dispensing nozzle communicates with the interior of the cavity, and the milk dispensing tube is connected to the milk dispensing nozzle. The milk dispensing tube communicates with the interior of the cavity through the milk dispensing nozzle.
[0008] Preferably, the extrusion unit is mounted on the mounting frame. The extrusion unit includes a motor, and a cam is connected to the output shaft of the motor. The cam has a protrusion for extruding the outer wall of the milk tube. The motor drives the cam to rotate, and the protrusion extrudes the outer wall of the milk tube, thereby reducing the cross-sectional area of the inner diameter of the milk tube.
[0009] Preferably, the diameter of the milk suction hole is smaller than the diameter of the milk outlet hole, and the milk inlet tube is connected to the outside of the milk suction tube; the water inlet includes a steam pipe provided on the upper shell, and the upper shell is also provided with an air pipe for air intake. The inside of the air pipe and the inside of the steam pipe are both connected to the milk passage. During the milk foaming process, the steam pipe introduces steam into the milk inlet. When cleaning is required, the temperature drops, and the steam pipe introduces hot water for cleaning into the milk inlet.
[0010] Preferably, the milk outlet tube is connected to a connecting tube, and the connecting tube has a protrusion protruding towards the extrusion unit. The interior of the protrusion is a moving cavity for moving the extrusion unit. The connecting tube has a through hole for the extrusion unit to pass through, and the through hole connects the interior of the connecting tube and the moving cavity. The extrusion unit extends into the interior of the connecting tube through the through hole.
[0011] Preferably, one end of the extrusion unit is connected to a drive unit for driving the extrusion unit to move, and the other end of the extrusion unit extends into the inside of the connecting tube. The extrusion unit includes a push rod and a plug located at the front end of the push rod. The end of the push rod away from the plug is loosely connected to the drive unit. A sealing ring is sleeved on the push rod. The sealing ring and the push rod move synchronously. The inner wall of the moving cavity is provided with a first inclined surface and a second inclined surface that abut against the sealing ring.
[0012] Preferably, the driving unit includes an electromagnet with an output rod connected to it. The output rod is loosely connected to the push rod. The electromagnet can apply a small force to push the push rod through the output rod, causing the plug to extend into the squeezing connecting tube until the cross-sectional area of the hole inside the connecting tube is reduced to approximately the same as the cross-sectional area of the milk suction hole.
[0013] Preferably, a spring is sleeved on the push rod, the spring is arranged outside the protrusion, one end of the spring is in contact with the outer wall of the protrusion, and the other end of the spring is in contact with the push rod.
[0014] Compared with the prior art, the advantages of this utility model are as follows: by squeezing the milk outlet tube by the squeezing unit, the cross-sectional area of the internal aperture of the milk outlet tube is reduced to be similar to that of the milk suction hole. 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 both the milk inlet tube and the milk outlet tube to the outside at the same time, achieving the effect of cleaning the inside of the milk inlet and the milk outlet tube at the same time. This means that no additional operation is required during cleaning, and the cleaning of the milk outlet tube and the milk inlet tube can be completed. At the same time, regardless of whether the highest water level of the external pipe of the milk suction tube is higher or lower than that of the milk frother, water can still be discharged to achieve the cleaning effect. Attached Figure Description
[0015] Figure 1 is a structural schematic diagram of this utility model;
[0016] Figure 2 is a cross-sectional structural diagram of this utility model;
[0017] Figure 3 is a cross-sectional structural diagram of this utility model;
[0018] Figure 4 is a structural schematic diagram of Embodiment 2 of this utility model;
[0019] Figure 5 is a cross-sectional structural diagram of the electromagnet in the de-energized state of Embodiment 2 of this utility model;
[0020] Figure 6 is a cross-sectional structural diagram of the electromagnet in the energized state of Embodiment 2 of this utility model.
[0021] Reference numerals: 1. Milk inlet; 2. Milk outlet; 3. Upper shell; 4. Lower shell; 5. Milk inlet tube; 6. Milk passage; 7. Cavity; 8. Milk suction hole; 9. Milk outlet hole; 10. Milk outlet tube; 11. Nipple; 12. Mounting bracket; 13. Motor; 14. Cam; 15. Protrusion; 16. Milk suction tube; 17. Air tube; 18. Steam tube; 19. Connecting tube; 20. Protrusion; 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 Implementation
[0022] The following drawings will disclose several embodiments of this utility model. For clarity, 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 this utility model. That is, in some embodiments of this utility model, these practical details are not essential. In addition, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.
[0023] It should be noted that all directional indicators in this utility model embodiment, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0024] Furthermore, in addition to indicating orientation or positional relationship, the aforementioned terms may also be used to indicate other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. For those skilled in the art, the specific meaning of these terms in this utility model can be understood according to the specific circumstances.
[0025] Furthermore, the terms "installation," "setting," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral structures; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or internal connections between two devices, components, or parts. The connection methods described herein are existing technologies without any modifications and are common knowledge to those skilled in the art. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0026] Furthermore, in this utility model, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the utility model. They are merely used to distinguish components or operations described with the same technical terms and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model. Example
[0027] As shown in Figures 1 to 3, this utility model provides a cleaning structure for a milk tube, including a mounting frame 12. The mounting frame 12 is provided with a milk inlet 1 and a milk outlet 2 connected to the milk inlet 1. The milk inlet 1 and the milk outlet 2 are respectively provided with a milk inlet unit and a milk outlet unit. The milk inlet 1 is connected to a water inlet for introducing cleaning water. Specifically, the milk outlet 2 is also provided with a squeezing unit that cooperates with the milk outlet unit. The cleaning water enters the milk inlet 1 from the water inlet. When the squeezing unit squeezes the milk outlet unit, the cross-sectional area of the internal aperture of the milk outlet unit decreases until the cross-sectional area of the internal aperture of the milk outlet unit is reduced to be approximately the same as the cross-sectional area of the internal aperture of the milk inlet unit. The pressure inside the milk inlet 1 is greater than the external pressure, and the cleaning water is discharged from the milk inlet unit and the milk outlet unit at the same time, achieving the effect of cleaning the inside of the milk inlet 1 and the inside of the milk outlet 2 simultaneously.
[0028] The milk inlet 1 includes an upper shell 3 and a lower shell 4 connected to each other. The milk inlet unit includes a milk inlet pipe 5 located at the bottom of the lower shell 4. The milk inlet 1 is provided with a milk passage 6 and a cavity 7 inside. Specifically, the milk inlet pipe 5 is connected to the milk passage 6 through a milk suction hole 8, and the milk passage 6 is connected to the cavity 7 through a milk outlet hole 9.
[0029] The milk dispensing unit includes a milk dispensing tube 10, and a milk dispensing nozzle 11 extends from the lower housing 4 toward the milk dispensing section 2. Specifically, the milk dispensing nozzle 11 is connected to the inside of the cavity 7, the milk dispensing tube 10 and the milk dispensing nozzle 11 are connected, and the milk dispensing tube 10 is connected to the inside of the cavity 7 through the milk dispensing nozzle 11.
[0030] The extrusion unit is mounted on the mounting frame 12. The extrusion unit includes a motor 13, and a cam 14 is connected to the output shaft of the motor 13. Specifically, the cam 14 is provided with a protrusion 15 for extruding the outer wall of the milk tube 10. The motor 13 drives the cam 14 to rotate, and the protrusion 15 extrudes the outer wall of the milk tube 10, thereby reducing the cross-sectional area of the inner diameter of the milk tube 10.
[0031] The diameter of the milk suction hole 8 is smaller than that of the milk outlet hole 9, and the milk inlet pipe 5 is externally connected to the milk suction pipe 16. Specifically, the water inlet includes a steam pipe 18 located on the upper shell 3. The upper shell 3 also has an air pipe 17 for air intake. Both the interior of the air pipe 17 and the interior of the steam pipe 18 are connected to the milk passage 6. During the milk foaming process, the steam pipe 18 introduces steam into the milk inlet 1. When cleaning is required, the temperature decreases, and the steam pipe 18 introduces hot water for cleaning into the milk inlet 1. The steam pipe 18 is connected to an external boiler.
[0032] The working principle of this embodiment is as follows: During the process of making milk foam, the high-speed jet of steam enters the milk passage 6 through the steam pipe 18, and then enters the cavity 7 through the milk outlet 9, so that the inside of the milk frother is filled with steam and a negative pressure is formed inside the milk frother, which draws milk from the milk inlet pipe 5 into the cavity 7. At the same time, the air pipe 17 presses the outside air into the milk frother, so that air is mixed into the milk and a foamed state is formed. The foamed milk is then discharged through the milk outlet pipe 10.
[0033] When the internal pipes of the milk frother need to be cleaned, the temperature inside the steam pipe 18 decreases, and the cleaning hot water in the boiler enters the milk inlet 1 through the steam pipe 18. Since the cross-sectional area of the milk outlet pipe 10 is usually larger than that of the milk suction hole 8, the pressure difference between the inside and outside cannot discharge the cleaning water. At this time, the user can turn on the motor 13. The output shaft of the motor 13 drives the cam 14 to rotate. During the rotation of the cam 14, the protrusion 15 squeezes the outer wall of the milk outlet pipe 10, which reduces the cross-sectional area of the internal aperture of the milk outlet pipe 10 until it is reduced to be similar to the cross-sectional area of the milk suction hole 8. The pressure inside the milk inlet 1 is greater than the external pressure, and the cleaning water is discharged from the milk inlet pipe 5 and the milk outlet pipe 10 at the same time, achieving the effect of cleaning the inside of the milk inlet 1 and the milk outlet 2 at the same time.
[0034] The advantage of this embodiment is that the squeezing action of the squeezing unit on the milk outlet tube 10 reduces the cross-sectional area of the internal aperture of the milk outlet tube 10 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 both the milk inlet tube 5 and the milk outlet tube 10 to the outside at the same time. This achieves the effect of cleaning the inside of the milk inlet section 1 and the milk outlet section 2 at the same time, so that no additional operation is required during cleaning. The cleaning of the milk outlet tube 10 and the milk inlet tube 5 can be completed. At the same time, regardless of whether the highest water level of the external pipe of the milk suction tube 16 is higher or lower than that of the milk frother, water can still be discharged to achieve the cleaning effect. Example
[0035] As shown in Figures 4 to 6, unlike Embodiment 1, in this embodiment, the milk outlet tube 10 is connected to a connecting tube 19, and the connecting tube 19 has a protrusion 20 protruding towards the squeezing unit. The interior of the protrusion 20 is a moving cavity 21 for moving the squeezing unit. Specifically, the connecting tube 19 has a through hole 22 for the squeezing unit to pass through. The through hole 22 connects the interior of the connecting tube 19 and the moving cavity 21, and the squeezing unit extends into the interior of the connecting tube 19 through the through hole 22.
[0036] One end of the extrusion unit is connected to a drive unit for driving the extrusion unit to move, and the other end of the extrusion unit extends into the interior of the connecting tube 19. The extrusion unit includes a push rod 23 and a plug 24 located 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 drive unit. Specifically, a sealing ring 25 is sleeved on the push rod 23. The sealing ring 25 and the push rod 23 move synchronously. The inner wall of the moving cavity 21 is provided with a first inclined surface 26 and a second inclined surface 27 that abut against the sealing ring 25.
[0037] The drive unit includes an electromagnet 28, on which an output rod 29 is connected. The output rod 29 is loosely connected to the push rod 23. Specifically, the electromagnet 28 can apply a small force to push the push rod 23 through the output rod 29, so that the plug 24 extends into the squeezing connecting tube 19 until the cross-sectional area of the hole inside the connecting tube 19 is reduced to be approximately the same as the cross-sectional area of the milk suction hole 8.
[0038] A spring 30 is fitted onto the push rod 23. The spring 30 is arranged outside the protrusion 20. One end of the spring 30 is in contact with the outer wall of the protrusion 20, and the other end of the spring 30 is in contact with the push rod 23. Other structures are the same as in Embodiment 1.
[0039] The working principle of this embodiment is as follows: When the electromagnet 28 is de-energized, the plug 24 is not inserted into the connecting pipe 19, the plug 24 is located in the through hole 22, the sealing ring 25 on the push rod 23 and the second inclined surface 27 are in contact connection to prevent the milk that comes out during the milk foam making process from leaking out of the moving chamber 21 to the outside, and the spring 30 is in a relaxed state.
[0040] When the milk frothing process is complete and the inside of the milk frother needs cleaning, the temperature inside the steam pipe 18 decreases, and the cleaning hot water in the boiler enters the milk inlet 1 through the steam pipe 18. This activates the electromagnet 28. With the electromagnet 28 energized, the output rod 29 on the electromagnet 28 pushes the push rod 23 and the plug 24 towards the connecting pipe 19. Because the push rod 23 and the output rod 29 are loosely connected, the electromagnet 28 requires only a small amount of force to push the push rod 23, without needing to withstand additional resistance. Only a very small amount of force is required. The electromagnet 28 can be used to achieve this; the plug 24 gradually extends into the inside of the connecting tube 19, the spring 30 is compressed, and the cross-sectional area of the inner diameter of the connecting tube 19 gradually decreases until the sealing ring 25 on the push rod 23 and the first inclined surface 26 abut and connect. The cross-sectional area of the inner diameter of the connecting tube 19 is reduced to be approximately the same as the cross-sectional area of the milk suction hole 8. The pressure inside the milk inlet 1 is greater than the external pressure, and the cleaning water is discharged from the milk inlet pipe 5 and the milk outlet pipe 10 at the same time, achieving the effect of cleaning the inside of the milk inlet 1 and the inside of the milk outlet 2 at the same time.
[0041] The advantage of this embodiment is that the cross-sectional area of the internal aperture of the connecting pipe 19 is reduced by the squeezing action of the squeezing unit on the pipeline unit. The electromagnet 28 only needs a small force to push the push rod 23 without bearing additional resistance. This can be achieved by using a very small electromagnet 28.
[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0043] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, welding, and bonding that are mature in the existing technology, and will not be described in detail here.
[0044] The above description is only a preferred embodiment of this utility model. For those skilled in the art, various modifications and variations can be made in the specific implementation and application scope based on the idea of this utility model. The content of this specification should not be construed as a limitation of this utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.
Claims
1. A cleaning structure for a coffee machine milk hose, comprising a mounting bracket, the mounting bracket having a milk inlet and a milk outlet communicating with the milk inlet, the milk inlet and the milk outlet respectively having a milk inlet unit and a milk outlet unit, and the milk inlet having a water inlet for introducing cleaning water, characterized in that: The milk outlet section is also equipped with a squeezing unit that cooperates with the milk outlet unit. The cleaning water flows into the milk inlet section from the water inlet section. When the squeezing unit squeezes the milk outlet unit, the cross-sectional area of the internal aperture of the milk outlet unit decreases until the cross-sectional area of the internal aperture of the milk outlet unit decreases to be similar to that of the internal aperture of the milk inlet unit. The pressure inside the milk inlet section is greater than the external pressure, and the cleaning water is discharged from the milk inlet unit and the milk outlet unit at the same time, achieving the effect of cleaning the inside of the milk inlet section and the inside of the milk outlet section at the same time.
2. The cleaning structure for a milk tube according to claim 1, characterized in that: The milk inlet section includes an upper shell and a lower shell connected to each other. The milk inlet unit includes a milk inlet pipe located at the bottom of the lower shell. The milk inlet section has a milk passage and a cavity inside. The milk inlet pipe is connected to the milk passage through a milk suction hole, and the milk passage is connected to the cavity through a milk outlet hole.
3. A cleaning structure for a milk tube according to claim 2, characterized in that: The milk dispensing unit includes a milk dispensing tube, and a milk dispensing nozzle is provided on the lower shell extending towards the milk dispensing section. The milk dispensing nozzle is connected to the inside of the cavity, and the milk dispensing tube is connected to the milk dispensing nozzle. The milk dispensing tube is connected to the inside of the cavity through the milk dispensing nozzle.
4. A cleaning structure for a milk tube according to claim 3, characterized in that: The extrusion unit is mounted on the mounting frame. The extrusion unit includes a motor, and a cam is connected to the output shaft of the motor. The cam has a protrusion for extruding the outer wall of the milk tube. The motor drives the cam to rotate, and the protrusion extrudes the outer wall of the milk tube, reducing the cross-sectional area of the inner diameter of the milk tube.
5. A cleaning structure for a milk tube according to claim 2, characterized in that: The diameter of the milk suction hole is smaller than that of the milk outlet hole, and the milk inlet tube is connected to the outside of the milk suction tube; the water inlet includes a steam pipe on the upper shell, and the upper shell is also provided with an air pipe for air intake. The inside of the air pipe and the inside of the steam pipe are connected to the milk passage. During the milk foaming process, the steam pipe introduces steam into the milk inlet. When cleaning is required, the temperature drops and the steam pipe introduces hot water for cleaning into the milk inlet.
6. A cleaning structure for a milk tube according to claim 3, characterized in that: The milk outlet tube is connected to a connecting tube, and the connecting tube has a protrusion protruding towards the extrusion unit. The inside of the protrusion is a moving cavity for moving the extrusion unit. The connecting tube has a through hole for the extrusion unit to pass through. The through hole connects the inside of the connecting tube and the moving cavity, and the extrusion unit extends into the inside of the connecting tube through the through hole.
7. A cleaning structure for a milk tube according to claim 6, characterized in that: One end of the extrusion unit is connected to a drive unit for driving the extrusion unit to move, and the other end of the extrusion unit extends into the inside of the connecting tube. The extrusion unit includes a push rod and a plug located at the front end of the push rod. The end of the push rod away from the plug is loosely connected to the drive unit. A sealing ring is sleeved on the push rod. The sealing ring and the push rod move synchronously. The inner wall of the moving cavity is provided with a first inclined surface and a second inclined surface that abut against the sealing ring.
8. A cleaning structure for a milk tube according to claim 7, characterized in that: The drive unit includes an electromagnet with an output rod connected to it. The output rod is loosely connected to a push rod. When the electromagnet applies a small force, it can push the push rod to move through the output rod, causing the plug to extend into the squeezing connecting tube until the cross-sectional area of the hole inside the connecting tube is reduced to approximately the same as the cross-sectional area of the milk suction hole.
9. A cleaning structure for a milk tube according to claim 7, characterized in that: A spring is fitted on the push rod. The spring is arranged outside the protrusion. One end of the spring is in contact with the outer wall of the protrusion, and the other end of the spring is in contact with the push rod.