Electronic expansion valve

Abstract

The application discloses an electronic expansion valve, which comprises a speed reduction mechanism, the speed reduction mechanism comprises at least two-stage planetary gear trains, the at least two-stage planetary gear trains comprise a final-stage planetary gear train, a sun gear of the final-stage planetary gear train is integrated on an annular carrier of a preceding-stage planetary gear train of the final-stage planetary gear train, the final-stage planetary gear train forms an output end of the speed reduction mechanism, and the annular carrier of the preceding-stage planetary gear train is injection molded by using high-temperature nylon and is added with glass fibers with a mass percentage of 25-35%. The electronic expansion valve can improve the strength of the sun gear and prolong the service life of the planetary gear train through the structural optimization of the sun gear of the planetary gear train.

Description

Technical Field

[0001] This invention relates to the field of valve component technology, and in particular to an electronic expansion valve. Background Technology

[0002] Multi-stage planetary gear reduction electronic expansion valves have a compact structure, high transmission efficiency, and a wide range of reduction ratio adjustment, and have become the development trend of reduction electronic expansion valves.

[0003] In electronic expansion valves, to avoid gear root breakage and to balance gear size and strength, the root of the sun gear is usually treated with material removal, meaning the root size is relatively smaller. Consequently, the sun gear of the last stage becomes the relatively weakest part of the planetary gear system. At the same time, to avoid pressure differences between components, the valve cavity in planetary gear reduction electronic expansion valves adopts a continuous design. Thus, the entire planetary gear system is in a fluid environment. When the valve is in a relatively high fluid temperature operating state for a long time, the sun gear is prone to root breakage due to insufficient strength, causing the valve to fail and become inoperable. Summary of the Invention

[0004] The purpose of this invention is to provide an electronic expansion valve that, by optimizing the structure of the sun gear in its planetary gear system, can improve the strength of the sun gear and extend the service life of the planetary gear system.

[0005] To solve the above-mentioned technical problems, the present invention provides an electronic expansion valve, including a reduction mechanism, comprising at least two stages of planetary gear trains, wherein the at least two stages of planetary gear trains include a final stage planetary gear train, the sun gear of the final stage planetary gear train is integrated on the planet carrier of the preceding stage planetary gear train, the final stage planetary gear train forms the output end of the reduction mechanism, and the planet carrier of the preceding stage planetary gear train is made of high-temperature nylon injection molding and has 25-35% glass fiber by mass added.

[0006] The electronic expansion valve provided by this invention has a reduction mechanism with at least two stages of planetary gear trains. The planet carrier of the first stage planetary gear train includes the sun gear of the second stage planetary gear train. That is, the planet carrier of the first stage planetary gear train integrates the sun gear of the second stage planetary gear train. The planet carrier with the integrated sun gear is injection molded from high-temperature nylon and has 25-35% glass fiber added by mass. This gives the sun gear in the second stage planetary gear train high strength and wear resistance, as well as good heat resistance. It can adapt to various operating conditions of the electronic expansion valve, especially relatively high-temperature fluid environments, reducing the risk of breakage of the meshing teeth of the first sun gear, which helps to extend the service life of the planetary gear train and ensure the reliability and effectiveness of valve operation.

[0007] As described above, the electronic expansion valve includes a first-stage planetary gear system, which includes a first sun gear. The first sun gear is the power input end of the reduction mechanism. The first sun gear is injection molded from PPS material and contains 10-15% carbon fiber and 25-30% PTFE material by mass.

[0008] As described above, the electronic expansion valve includes a reduction mechanism comprising a three-stage planetary gear system. The first-stage planetary gear system includes a first planet carrier, the second-stage planetary gear system includes a second planet carrier and a second sun gear, and the third-stage planetary gear system includes a third planet carrier and a third sun gear. The second sun gear is integrally formed at the lower end of the first planet carrier, and the third sun gear is integrally formed at the lower end of the second planet carrier. The third planet carrier is the power output end of the reduction mechanism. Both the first and second planet carriers are injection molded from high-temperature nylon and contain 25-35% glass fiber by weight.

[0009] In the electronic expansion valve described above, the high-temperature nylon is nylon PA46.

[0010] As described above, the planet carrier of the preceding planetary gear train also contains 10-15% PTFE material by mass in the electronic expansion valve.

[0011] As described above, the planet carrier of the preceding planetary gear train undergoes a water bath treatment and air drying treatment for a set time after injection molding.

[0012] As described above, the electronic expansion valve has a set time of 24 hours or more.

[0013] As described above, in the electronic expansion valve, each stage of the planetary gear system includes planetary gears, which are made of metal powder metallurgy.

[0014] The electronic expansion valve as described above further includes a valve seat component, and the reduction mechanism further includes a fixed gear, which is fixed relative to the valve seat component; the fixed gear is injection molded from PPS material and contains 30-40% glass fiber by weight.

[0015] As described above, in the electronic expansion valve, each stage of the planetary gear system shares a fixed gear. Each stage of the planetary gear system includes meshing planetary gears and a sun gear, and each planetary gear meshes with the fixed gear. Attached Figure Description

[0016] Figure 1 This is a cross-sectional schematic diagram of an electronic expansion valve provided in one embodiment of the present invention;

[0017] Figure 2 for Figure 1 A partial enlarged view of the intermediate speed reduction mechanism;

[0018] Figure 3 for Figure 1 A cross-sectional schematic diagram of the first-stage planetary gear system of the intermediate reduction mechanism.

[0019] Explanation of reference numerals in the attached figures:

[0020] Valve seat assembly 10, valve port 101, rotor assembly 20, reduction mechanism 30, lead screw 40, nut 50, valve needle 60, housing 70;

[0021] First-stage planetary gear system 31, first sun gear 311, first planet gear 312, first planet carrier 313;

[0022] Second-stage planetary gear system 32, second sun gear 321, second planet gear 322, second planet carrier 323;

[0023] Third-stage planetary gear system 33, third sun gear 331, third planet gear 332, third planet carrier 333;

[0024] Fixed gear 34. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Please refer to Figure 1 , Figure 1 This is a cross-sectional schematic diagram of an electronic expansion valve provided in one embodiment of the present invention.

[0027] In this embodiment, the electronic expansion valve includes a valve seat component 10, a drive component, a reduction mechanism 30, a threaded mechanism, a valve needle 60, and a housing 70. The drive component includes a rotor component 20 and a coil (not shown in the figure), the threaded mechanism includes a lead screw 40 and a nut 50, which are threadedly connected, and the housing 70 is fixed to the valve seat component 10. The rotor component 20, the reduction mechanism 30, the threaded mechanism, and the valve needle 60 are all located in the cavity enclosed by the housing 70 and the valve seat component 10.

[0028] The valve seat component 10 has two interfaces, which are respectively connected to two pipes. The valve seat component 10 also has a valve port 101, and the two interfaces are connected through the valve port 101.

[0029] During operation, the rotor component 20 is driven to rotate by the coil, and the lead screw 40 is driven to rotate by the reduction mechanism 30. Under the action of the threaded engagement between the lead screw 40 and the nut 50, the lead screw 40 can move along the axial direction of the valve seat component 10 to drive the valve needle 60 to move, thereby adjusting the opening of the valve port 101.

[0030] The connection relationships and action coordination relationships between the above-mentioned components can all be realized based on existing technologies, and will not be described in detail here.

[0031] Please refer to this as well. Figure 2 , Figure 2 for Figure 1 A partial enlarged view of the intermediate speed reduction mechanism.

[0032] In this embodiment, the reduction mechanism 30 adopts a planetary gear system structure. The following description uses the three-stage planetary gear system shown in the figure as an example. It can be understood that in actual applications, the number of stages of the planetary gear system can be set as needed, and the relevant structural settings can be adaptively adjusted based on the following description.

[0033] For ease of description, the three-stage planetary gear system is referred to as the first-stage planetary gear system 31, the second-stage planetary gear system 32, and the third-stage planetary gear system 33, respectively. The first-stage planetary gear system 31 includes a first sun gear 311, first planet gears 312, and a first planet carrier 313. Multiple first planet gears 312 may be provided, all mounted on the first planet carrier 313 via gear shafts, and each first planet gear 312 meshes with the first sun gear 311. The second-stage planetary gear system 32 includes a second sun gear 321, ... The second planetary gear 322 and the second planetary carrier 323, with multiple second planetary gears 322, are all mounted on the second planetary carrier 313 via gear shafts. Each second planetary gear 322 meshes with the second sun gear 321. The third-stage planetary gear system 33 includes a third sun gear 331, third planetary gears 332, and a third planetary carrier 333. Multiple third planetary gears 332 are also possible, all mounted on the third planetary carrier 333 via gear shafts. Each third planetary gear 332 meshes with the third sun gear 333. In other words, each stage of the planetary gear system includes a sun gear, planetary gears, and a planetary carrier.

[0034] The reduction mechanism 30 also includes a fixed gear 34, which is fixed relative to the valve seat component 10. The aforementioned three-stage planetary gear system shares a single fixed gear 34. Specifically, each planet gear in each stage of the planetary gear system meshes with the fixed gear 34. That is, each first planet gear 312, each second planet gear 322, and each third planet gear 332 meshes with the fixed gear 34. The fixed gear 34 is in the form of an internal gear ring, and its inner circumferential wall surface is provided with tooth structures that mesh with each planet gear.

[0035] Please refer to this as well. Figure 3, Figure 3 for Figure 1 A cross-sectional schematic diagram of the first-stage planetary gear system of the intermediate reduction mechanism. Figure 3 In the example shown, the first-stage planetary gear system has three first planetary gears 312. In practical applications, the number of first planetary gears 312 can be adjusted as needed. The structures of the second-stage and third-stage planetary gear systems can be referenced from [the example shown]. Figure 3 The first-stage planetary gear system shown is understood and will not be described in detail again.

[0036] In this embodiment, the first sun gear 311 of the first-stage planetary gear system is the power input end of the reduction mechanism 30. Specifically, the first sun gear 311 is fixed relative to the rotor component 20. When the rotor component 20 rotates, it can drive the first sun gear 311 to rotate together. The third gear carrier 333 of the third-stage planetary gear system is the power output end of the reduction mechanism 30. Specifically, the third gear carrier 333 is fixed relative to the lead screw 40. The third gear carrier 333 can drive the lead screw 40 to rotate.

[0037] When the rotor assembly 20 rotates, power can be transmitted to the lead screw 40 through the first-stage planetary gear 31, the second-stage planetary gear system 32 and the third-stage planetary gear system 33, causing the lead screw 40 to rotate. Through the threaded engagement between the lead screw 40 and the nut 50, the lead screw 40 can move axially along the valve seat assembly 10 to drive the valve needle 60 to move.

[0038] In this embodiment, the first sun gear 311 is injection molded from PPS (Polyphenylene sulfide) material, and contains 10-15% carbon fiber and 25-30% PTFE (Polytetrafluoroethylene) material by weight. The first sun gear 311 made in this way has good heat resistance, lubricity and wear resistance, and relatively high strength. It can adapt to various working conditions of electronic expansion valves, especially relatively high temperature fluid environments, reducing the risk of meshing tooth breakage of the first sun gear 311, which helps to extend the service life of the planetary gear system and ensure the reliability and effectiveness of valve operation.

[0039] In this embodiment, the lower end of the planet carrier of the previous stage planetary gear system is integrally formed with the sun gear of the next stage planetary gear system. That is, the sun gear of the next stage planetary gear system and the planet carrier of the previous stage are integrally formed and designed as a single component. This helps to simplify the number of parts in the reduction mechanism 30 and facilitates assembly and coordination.

[0040] Here, the preceding and following planetary gear trains are clearly two adjacent stages of planetary gear trains. In these adjacent stages, the planetary gear train closer to the power input end is called the preceding stage, and the one farther from the power input end is called the following stage. Taking the first and second stage planetary gear trains as an example, the first stage is the preceding stage, and the second stage is the following stage; similarly, taking the second and third stage planetary gear trains as an example, the second stage is the preceding stage, and the third stage is the following stage.

[0041] In this embodiment, the lower end of the first planetary carrier 313 is integrally formed with the second sun gear 321, and the lower end of the second planetary carrier 323 is integrally formed with the third sun gear 331. Since the planetary gear system has three stages, the third planetary carrier 333 is fixedly connected to the lead screw 40 as the power output end, so the sun gear is not integrated on the third planetary carrier 333.

[0042] Specifically, each planet carrier with a sun gear is integrally molded using high-temperature nylon injection molding, and contains 25-35% glass fiber by weight. In the illustrated example, the integrally molded planet carriers with sun gears are the first planet carrier 313 and the second planet carrier 323.

[0043] In this way, high-temperature nylon has good high-temperature resistance, and the addition of glass fiber can improve mechanical properties, resulting in high strength and wear resistance. This effectively improves the strength of the second sun gear 321 integrated on the first planetary carrier 313 and the strength of the third sun gear 331 integrated on the second planetary carrier 323. Furthermore, it is suitable for high-temperature fluid environments. Combined with the aforementioned first sun gear 311, it can effectively extend the service life of the reduction mechanism 20 and broaden the fluid operating temperature range of the electronic expansion valve.

[0044] The high-temperature nylon used here can be selected based on the operating conditions of the electronic expansion valve. Specifically, high-temperature nylon PA46 can be used, which has good heat resistance, mechanical strength and wear resistance.

[0045] Furthermore, 10-15% by weight of PTFE material can be added to the planet carriers that integrate the sun gear, namely the first planet carrier 313 and the second planet carrier 323, to increase their lubricity and wear resistance.

[0046] Specifically, after injection molding, the planetary carriers integrated with the sun gear, namely the first planetary carrier 313 and the second planetary carrier 323, undergo water bath treatment and air drying treatment for a set time to ensure the stability of the shape and size of the planetary carriers.

[0047] Specifically, a room temperature water bath treatment is sufficient, and the above-mentioned time setting can be selected as 24 hours or more. Of course, it can be adjusted according to specific needs in actual application.

[0048] Through testing and verification, as the number of times the electronic expansion valve operates increases, the lifespan of the planetary carrier shows good performance, whether at normal fluid temperature (e.g., 20℃) or at relatively high fluid temperature (e.g., 70℃). In particular, at high fluid temperature, as the number of times the electronic expansion valve operates increases, the strength of the planetary carrier hardly changes, and the lifespan is greatly enhanced.

[0049] In other embodiments, only the aforementioned second planetary carrier 323 may be manufactured using the aforementioned materials and processing methods, while the first planetary carrier 313 may still use existing materials or existing structures. Relatively speaking, in a multi-stage planetary gear system, the sun gear of the last-stage planetary gear system is the weakest part of the entire planetary gear system. Therefore, by integrating the sun gear of the last-stage planetary gear system onto the planetary carrier of its preceding stage planetary gear system and manufacturing the planetary carrier of the preceding stage planetary gear system using the aforementioned materials and processing methods, the service life of the planetary gear system can be extended. In other words, in the embodiment of the above-mentioned reduction mechanism having a three-stage planetary gear system, it is only necessary to integrate the sun gear 331 of the third-stage planetary gear system 33 onto the second planetary carrier 323 of the preceding stage planetary gear system, i.e., the second-stage planetary gear system, and manufacture the second planetary carrier 323 using the aforementioned materials and processing methods.

[0050] In other screenings, if the reduction mechanism uses a planetary gear system of four or more stages, its structural design is similar. That is, the sun gear of the last stage planetary gear system can be integrated onto the planet carrier of the previous stage planetary gear system, and the planet carrier can be made using the aforementioned materials and processing methods. Alternatively, the sun gears of all subsequent stage planetary gear systems can be integrated onto the planet carriers of the corresponding previous stage planetary gear systems, and some or all planet carriers with integrated sun gears can be made using the aforementioned materials and processing methods.

[0051] In the specific design, each planetary gear in the aforementioned planetary gear system is made of metal powder metallurgy to improve the strength of each planetary gear and prevent the tooth structure of the planetary gear from breaking.

[0052] In the specific design, the fixed gear 34 is injection molded from PPS material and contains 30-40% glass fiber by weight to ensure the strength, wear resistance and high temperature resistance of the fixed gear 34.

[0053] In this embodiment, the power transmission of the reduction mechanism 30 is as follows: the first sun gear 311 rotates under the drive of the rotor component 20, and the first sun gear 311 drives the first planet gear 312 meshing with it to rotate. Due to the constraint of the fixed gear 34, when the first planet gear 312 rotates, it drives the first planet carrier 313 to rotate. The second sun gear 321, which is integral with the first planet carrier 313, rotates accordingly, driving the second planet gear 322 to rotate. Under the constraint of the fixed gear 34, it drives the second planet carrier 323 to rotate. The third sun gear 331, which is integral with the second planet carrier 323, rotates accordingly, driving the third planet gear 332 to rotate. Under the constraint of the fixed gear 34, it drives the third planet carrier 333 to rotate. When the third planet carrier 333 rotates, it drives the lead screw 40 fixed to it to rotate together.

[0054] It is understandable that, based on the aforementioned three-stage planetary gear system in the reduction mechanism 30, the third-stage planetary gear system 33 serves as the final-stage planetary gear system and is the power output end of the reduction mechanism 30.

[0055] The above description uses the three-stage planetary gear system shown in the figure as an example. In other embodiments, the number of stages of the planetary gear system can be set as needed, and the relevant structures can be adapted by referring to the above description. They will not be described one by one.

[0056] The electronic expansion valve provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. An electronic expansion valve comprising a speed reduction mechanism, characterized in that, the speed reduction mechanism comprises three-stage planetary gear trains, the first-stage planetary gear train comprises a first carrier, the second-stage planetary gear train comprises a second carrier and a second sun gear, and the third-stage planetary gear train comprises a third carrier and a third sun gear; the lower end of the first carrier is integrally formed with the second sun gear; the lower end of the second carrier is integrally formed with the third sun gear; the third carrier is the power output end of the speed reduction mechanism; the first carrier and the second carrier are both injection molded with high-temperature nylon and added with 25-35% glass fiber by mass percentage; the first carrier and the second carrier are also added with 10-15% PTFE material by mass percentage; the first carrier and the second carrier are further subjected to water bath treatment and air drying treatment for a set length of time after injection molding; the first-stage planetary gear train comprises a first sun gear, the first sun gear is the power input end of the speed reduction mechanism, the first sun gear is injection molded with PPS material and added with 10-15% carbon fiber by mass percentage and 25-30% PTFE material by mass percentage; the electronic expansion valve further comprises a valve seat component, the speed reduction mechanism further comprises a fixed gear, and the fixed gear is fixed opposite to the valve seat component; the fixed gear is injection molded with PPS material and added with 30-40% glass fiber by mass percentage.

2. The electronic expansion valve according to claim 1, characterized in that The high-temperature nylon is nylon PA46.

3. The electronic expansion valve according to claim 1 or 2, characterized in that, The set length of time is 24 hours or more.

4. The electronic expansion valve according to claim 1 or 2, characterized in that, Each stage of planetary gear train comprises a planet gear, and the planet gear is made of metal powder metallurgy.

5. The electronic expansion valve according to claim 1 or 2, characterized by The fixed gear is shared by all stages of planetary gear trains, each stage of planetary gear train comprises a planet gear and a sun gear in meshing cooperation, and each planet gear is in meshing cooperation with the fixed gear.

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