Isotope power supply device

Abstract

The invention relates to the technical field of isotope power supplies, and provides an isotope power supply device which comprises an outer shell, an inner shell, an isotope heat source, a thermoelectric conversion module and a shielding structure. A shielding cavity is formed in the shell; an accommodating cavity is formed in the inner shell, the inner shell is arranged in the shielding cavity, and the inner shell is separated from the wall surface of the shielding cavity; the isotope heat source is arranged in the accommodating cavity and is separated from the wall surface of the accommodating cavity; the thermoelectric conversion module is arranged in the accommodating cavity and is used for converting heat generated by the isotope heat source into electric energy; the shielding structure fills a gap between the inner shell and the wall surface of the shielding cavity. According to the isotope power supply device provided by the embodiment of the invention, the shielding performance of the isotope power supply device can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of isotope power supply, and in particular to an isotope power supply device. Background Art

[0002] This section is intended to provide a background or context for the embodiments of the present application. No description herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] Isotope power devices generally refer to devices that use radioactive isotope decay energy as energy and use one or more energy conversion devices to convert decay energy into electrical energy. According to the form of energy conversion, it can be divided into thermoelectric conversion (temperature difference type), radiovoltaic conversion, radiophotovoltaic, Stirling conversion, etc.

[0004] Thermoelectric conversion isotope power supply devices (hereinafter referred to as isotope power supply devices) are power supply devices that convert the heat (decay heat) generated by radioactive isotopes into electrical energy through thermoelectric conversion equipment. They are widely used in many fields, especially in extreme environments such as deep space exploration and deep sea exploration. Isotope power supply devices are favored because of their long-lasting, stable and reliable energy supply. For example, in the flight missions of scientific experiments on Mars exploration and lunar exploration projects, isotope power supply devices have played an important role in the supply of electricity and heat energy for spacecraft. For another example, isotope power supply devices can also be widely used in unmanned measurement stations in remote areas, lighthouses in distant seas, navigation lights, etc.

[0005] An isotope power supply device usually includes an isotope heat source, and the radiation emitted by the isotope heat source can easily affect the environment. Summary of the invention

[0006] In view of this, an embodiment of the present application hopes to provide an isotope power supply device that can improve the shielding performance of the isotope power supply device.

[0007] The embodiment of the present application provides an isotope power supply device, comprising:

[0008] A housing forming a shielding cavity;

[0009] An inner shell is formed with a containing cavity, the inner shell is arranged in the shielding cavity, and the inner shell is spaced apart from the wall surface of the shielding cavity;

[0010] an isotope heat source, disposed in the containing chamber, the isotope heat source being spaced apart from a wall surface of the containing chamber;

[0011] A thermoelectric conversion module is disposed in the accommodating cavity, and is used to convert the heat generated by the isotope heat source into electrical energy;

[0012] The shielding structure fills the gap between the inner shell and the wall surface of the shielding cavity.

[0013] In some embodiments, the shielding structure includes a lead structure.

[0014] In some embodiments, the isotope power supply device includes a thermal insulation component, and the thermal insulation component is arranged between the isotope heat source and the inner shell.

[0015] In some embodiments, the thermoelectric conversion module passes through the thermal insulation component, and the thermoelectric conversion module contacts the isotope heat source and the inner shell.

[0016] In some embodiments, the isotope power supply device includes a heat-conducting column located in the shielding cavity, and the heat-conducting column connects the inner shell and the outer shell.

[0017] In some embodiments, the length of the thermally conductive column is not less than the distance between the inner shell and the outer shell.

[0018] In some embodiments, the thermally conductive column extends along a curve.

[0019] In some embodiments, the isotope power supply device includes a support column, which is disposed at the bottom of the inner shell and connects the inner shell and the outer shell.

[0020] In some embodiments, the isotope power supply device includes heat sink fins connected to the outer surface of the housing.

[0021] In some embodiments, the isotope power supply device includes a heat-conducting column, the heat-conducting column includes a first connecting surface connected to the outer shell, and the heat dissipating fins include a second connecting surface connected to the outer shell, with the plane perpendicular to the top and bottom directions as the projection surface, and the projection of the second connecting surface is located within the projection range of the first connecting surface.

[0022] In the isotope power supply device provided in the embodiment of the present application, the isotope heat source and the inner shell are not in contact, the heat conduction between the isotope heat source and the inner shell is weakened, the heat transferred to the shell wall of the inner shell has a large loss, and the temperature of the inner shell is lower than the temperature of the isotope heat source. At the same time, the accommodating cavity is a closed cavity, the heat generated by the isotope heat source is difficult to diffuse outward, and the inner shell has a good heat insulation effect. At the same time, the shielding structure and the isotope heat source are isolated from each other, the shielding structure and the isotope heat source are not in contact, the heat transferred to the shielding structure via the inner shell is small, and the temperature of the shielding structure is low, which can avoid the problem of the shielding structure melting due to the high temperature of the shielding structure to a certain extent, and play a good protective role on the shielding structure. In addition, the shielding cavity is a closed cavity, and the rays emitted by the isotope heat source can be effectively shielded by the shielding structure and the shielding cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of an isotope power supply device provided in some embodiments of the present application;

[0024] Figure 2 for Figure 1 Cross-sectional view at position aa;

[0025] Figure 3 for Figure 2 Enlarged view of point A in the middle.

[0026] Description of Reference Numerals

[0027] Isotope power supply device 10;

[0028] Shell 1; shielding cavity 1a;

[0029] Inner shell 2; accommodating chamber 2a;

[0030] Isotope heat source 3; thermoelectric conversion module 4; shielding structure 5; thermal insulation component 6;

[0031] Heat conducting column 7; first connecting surface 7a;

[0032] Support column 8;

[0033] Heat dissipation fins 9; second connecting surface 9a. DETAILED DESCRIPTION

[0034] The following is a further detailed description of the implementation of the present application in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but cannot be used to limit the scope of the present application.

[0035] The various specific technical features and embodiments described in the specific implementation methods can be combined in any suitable manner without contradiction. For example, different implementation methods can be formed by combining different specific technical features / embodiments. In order to avoid unnecessary repetition, the various possible combinations of the specific technical features / embodiments in this application are no longer described separately. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] See also Figures 1 to 3, an embodiment of the present application provides an isotope power supply device 10, including an outer shell 1, an inner shell 2, an isotope heat source 3, a thermoelectric conversion module 4 and a shielding structure 5. The outer shell 1 forms a shielding cavity 1a; the inner shell 2 forms a accommodating cavity 2a, the inner shell 2 is arranged in the shielding cavity 1a, and the inner shell 2 is separated from the wall of the shielding cavity 1a. In other words, the inner shell 2 and the outer shell 1 are not in contact. Among them, the shielding cavity 1a and the accommodating cavity 2a are isolated from each other, the accommodating cavity 2a and the shielding cavity 1a are not connected, the shielding cavity 1a and the external air are not connected, and the shielding cavity 1a and the accommodating cavity 2a are both closed cavities.

[0037] The isotope heat source 3 is arranged in the accommodating chamber 2a, and the isotope heat source 3 is separated from the wall of the accommodating chamber 2a; the thermoelectric conversion module 4 is arranged in the accommodating chamber 2a, and the thermoelectric conversion module 4 is used to convert the heat generated by the isotope heat source 3 into electrical energy; the shielding structure 5 fills the gap between the inner shell 2 and the wall of the shielding chamber 1a. In other words, the isotope power supply device 10 provided in the embodiment of the present application is a thermoelectric conversion type isotope power supply device.

[0038] The isotope heat source 3 generates heat through isotope decay, and the heat is converted into electrical energy when flowing through the thermoelectric conversion module 4 and is output through the thermoelectric conversion module 4 .

[0039] The isotope heat source 3 is separated from the wall of the containing chamber 2a, that is, the isotope heat source 3 is not in contact with the inner shell 2, and the heat transferred to the shell wall of the inner shell 2 has a large loss, and the temperature of the inner shell 2 is lower than the temperature of the isotope heat source 3. At the same time, the containing chamber 2a is a closed cavity, and the heat generated by the isotope heat source 3 is difficult to diffuse outward, and the inner shell 2 has a good heat insulation effect.

[0040] The specific material of the isotope heat source 3 is not limited. For example, the isotope heat source 3 can be prepared using strontium-90 isotope, that is, strontium-90 isotope is the source of heat.

[0041] The shielding structure 5 is used to block or weaken the rays, such as X-rays, emitted by the isotope heat source 3. The shielding structure 5 is arranged in the shielding cavity 1a, and the shielding structure 5 and the isotope heat source 3 are isolated from each other, and the shielding structure 5 and the isotope heat source 3 are not in contact. On the one hand, the heat transferred to the shielding structure 5 via the inner shell 2 is small, which plays a good protective role for the shielding structure 5. On the other hand, the shielding cavity 1a is a closed cavity, and the rays emitted by the isotope heat source 3 can be effectively shielded by the shielding structure 5 and the shielding cavity 1a.

[0042] In the isotope power supply device 10 provided in the embodiment of the present application, the isotope heat source 3 and the inner shell 2 are not in contact, the heat conduction between the isotope heat source 3 and the inner shell 2 is weakened, the heat transferred to the shell wall of the inner shell 2 has a large loss, and the temperature of the inner shell 2 is lower than the temperature of the isotope heat source 3. At the same time, the accommodating cavity 2a is a closed cavity, the heat generated by the isotope heat source 3 is difficult to diffuse outward, and the inner shell 2 has a good heat insulation effect. At the same time, the shielding structure 5 is isolated from the isotope heat source 3, the shielding structure 5 and the isotope heat source 3 are not in contact, the heat transferred to the shielding structure 5 through the inner shell 2 is small, and the temperature of the shielding structure 5 is low, which can avoid the problem of the shielding structure 5 melting due to the excessive temperature of the shielding structure 5 to a certain extent, and play a good protective role for the shielding structure 5. In addition, the shielding cavity 1a is a closed cavity, and the rays emitted by the isotope heat source 3 can be effectively shielded by the shielding structure 5 and the shielding cavity 1a.

[0043] In one embodiment, please refer to Figure 1 and Figure 2 , the inner shell 2 and the outer shell 1 are both hollow cylindrical structures.

[0044] In the related art, the isotope heat source uses metal tungsten as the material for shielding radiation. The cost of metal tungsten is relatively high and is subject to regulation, which makes it inconvenient to mass-produce isotope power supply devices, thus limiting their application.

[0045] In some embodiments, the shielding structure 5 includes a lead structure. That is, the shielding structure 5 is a structure made of metal lead. Compared with the related art, on the one hand, the atomic number of lead is 82, which is higher than the atomic number of tungsten, which is 72. The shielding structure 5 made of metal lead has stronger shielding performance. On the other hand, the density of metal lead is 11.34 g / cm 3 (grams per cubic centimeter), which is lower than the density of tungsten metal 19.35g / cm 3 Therefore, the half-value thickness of metal lead is less than the half-value thickness of metal tungsten, and at the same time, the cost of metal lead is lower. In this way, the cost of the shielding structure 5 prepared by metal lead can be greatly reduced, which is beneficial to the promotion of the isotope power supply device 10 and broadens the application field of the isotope power supply device 10.

[0046] Half-value thickness refers to the thickness of the material required to reduce the radiation dose (such as exposure rate or absorbed dose rate) to half of the initial value on a specific radiation beam path.

[0047] For some examples, see Figure 1 and Figure 2 The isotope power supply device 10 includes a thermal insulation component 6 , and the thermal insulation component 6 is arranged between the isotope heat source 3 and the inner shell 2 .

[0048] The heat-insulating member 6 refers to a structure made of heat-insulating materials. The heat-insulating member 6 can be used to collect excess heat, release it in a timely and stable manner, and have a small gradient change and good heat uniformity. In this way, by providing the heat-insulating member 6, it is possible to prevent the isotope heat source 3 from generating too much heat, causing the local temperature of the inner shell 2 to be high, and causing damage to the shielding structure 5. Exemplarily, the heat-insulating member 6 can be heat-insulating cotton.

[0049] In one embodiment, the heat-insulating member 6 fills the gap between the isotope heat source 3 and the wall surface of the accommodating chamber 2a.

[0050] For some examples, see Figure 1 and Figure 2 The thermoelectric conversion module 4 passes through the thermal insulation component 6 , and the thermoelectric conversion module 4 contacts the isotope heat source 3 and the inner shell 2 .

[0051] Exemplarily, the thermal insulation member 6 forms a limiting hole, and the hole wall of the limiting hole abuts against the circumferential surface of the thermoelectric conversion module 4. In this way, on the one hand, the thermal insulation member 6 has good thermal conductivity, and the thermoelectric conversion module 4 is in contact with the thermal insulation member 6. Heat can be transferred to the thermoelectric conversion module 4 through the thermal insulation member 6, ensuring that a larger heat flow passes through the thermoelectric conversion module 4, thereby improving the thermal utilization rate and increasing the electrical energy output by the thermoelectric conversion module 4. On the other hand, the isotope heat source 3 can be regarded as the hot end, and the inner shell 2 can be regarded as the cold end. The temperature of the hot end is higher than the temperature of the cold end. The thermoelectric conversion module 4 is respectively connected to the hot end and the cold end. The two connecting ends of the thermoelectric conversion module 4 have a temperature difference, which can improve the thermoelectric conversion efficiency.

[0052] Heat flow is the rate at which heat is transferred through an object per unit time.

[0053] In one embodiment, please refer to Figure 2 There are multiple thermoelectric conversion modules 4, and the multiple thermoelectric conversion modules 4 are evenly spaced and distributed along the circumferential direction, so that the thermoelectric conversion efficiency can be further improved.

[0054] It should be noted that, in the present application, a plurality refers to a quantity including two or more.

[0055] For some examples, see Figure 1 and Figure 2 The isotope power supply device 10 includes a heat-conducting column 7 located in the shielding cavity 1 a , and the heat-conducting column 7 connects the inner shell 2 and the outer shell 1 .

[0056] The heat-conducting column 7 is used to guide the heat transferred to the inner shell 2 to the outer shell 1, so as to reduce the temperature of the inner shell 2. On the one hand, the heat transferred to the shielding structure 5 via the inner shell 2 is further reduced, ensuring that the shielding structure 5 will not be damaged by the heat generated by the isotope heat source 3. On the other hand, the temperature difference between the hot end and the cold end is increased, which can improve the thermoelectric conversion efficiency. On the other hand, the heat-conducting column 7 plays a supporting role and can enhance the stability of the inner shell 2.

[0057] The specific material of the heat-conducting column 7 is not limited. For example, the heat-conducting column 7 can be made of alloy material, or a composite structure such as copper, steel, heat pipe, etc. can be used to improve heat exchange efficiency.

[0058] The specific material of the shell 1 is not limited. For example, the shell 1 can be made of high-strength and high-thermal conductivity materials such as steel, alloy, and titanium alloy to improve heat exchange efficiency.

[0059] The specific material of the inner shell 2 is not limited. For example, the inner shell 2 can be made of high-temperature alloy steel or inorganic high thermal conductivity material to improve heat exchange efficiency.

[0060] In one embodiment, please refer to Figure 2 There are multiple heat-conducting columns 7, and the multiple heat-conducting columns 7 are evenly spaced and distributed along the circumference. In this way, the multiple heat-conducting columns 7 can accelerate the cooling of the inner shell 2, thereby further improving the thermoelectric conversion efficiency. At the same time, the evenly distributed multiple heat-conducting columns 7 are conducive to uniform heat transfer and improve thermal uniformity.

[0061] In one embodiment, the inner shell 2 and the outer shell 1 are both connected to the heat-conducting column 7 by welding, so that the connection stability among the inner shell 2, the outer shell 1 and the heat-conducting column 7 can be enhanced.

[0062] For some examples, see Figure 2 , the length of the heat-conducting column 7 is not less than the distance between the inner shell 2 and the outer shell 1.

[0063] Normally, the half-value thickness of the material used for the thermally conductive column 7 is greater than the half-value thickness of the material used for the shielding structure 5. Thus, when the length of the thermally conductive column 7 is equal to the distance between the inner shell 2 and the outer shell 1, part of the rays emitted by the isotope heat source 3 can be emitted outward through the thermally conductive column 7, affecting the shielding performance of the isotope power supply device 10.

[0064] The length of the thermally conductive column 7 is not less than the distance between the inner shell 2 and the outer shell 1. Exemplarily, the thermally conductive column 7 is obliquely arranged between the inner shell 2 and the outer shell 1. By extending the length of the thermally conductive column 7 and extending the path of the rays in the thermally conductive column 7, the rays can be prevented from penetrating the thermally conductive column 7 to a certain extent, thereby enhancing the shielding effect of the thermally conductive column 7.

[0065] For some examples, see Figure 2 , the heat-conducting column 7 extends along the curve. Specifically, the heat-conducting column 7 is substantially in a columnar structure, and the central axis of the heat-conducting column 7 extends along the curve.

[0066] It should be noted that the rays emitted by the isotope heat source 3 are usually propagated in a straight line. When the heat-conducting column 7 extends in a straight line, that is, the central axis of the heat-conducting column 7 extends in a straight line, part of the rays can penetrate the heat-conducting column 7 and be emitted outward. The heat-conducting column 7 is set to extend along a curve, and even if part of the rays penetrate the heat-conducting column 7, they will eventually enter the shielding structure 5, thereby ensuring the shielding performance of the isotope power supply device 10.

[0067] In one embodiment, please refer to Figure 2 , the heat-conducting column 7 has a wavy structure. In one embodiment, the heat-conducting column 7 has an arc structure.

[0068] For some examples, see Figure 1 and Figure 2 The isotope power supply device 10 includes a support column 8, which is disposed at the bottom of the inner shell 2 and connects the inner shell 2 and the outer shell 1. In this way, the support column 8 supports the inner shell 2, and together with the heat-conducting column 7, supports the inner shell 2 and its internal structure, ensures the stability of the overall structure, and reduces the load of the shielding structure 5 to prevent the shielding structure 5 from being damaged. In addition, the support column 8 can also be used to guide the heat transferred to the inner shell 2 to the outer shell 1, thereby improving the heat exchange efficiency.

[0069] The specific material of the heat-conducting column 7 is not limited. For example, the heat-conducting column 7 can be made of high-strength and high-thermal conductivity materials such as steel, alloy, and inorganic materials to improve heat exchange efficiency and load-bearing performance.

[0070] In one embodiment, please refer to Figure 1 There are multiple heat-conducting columns 7, and the multiple heat-conducting columns 7 are evenly spaced and distributed along the circumferential direction.

[0071] For some examples, see Figure 1 and Figure 2 The isotope power supply device 10 includes heat dissipation fins 9, which are connected to the outer surface of the housing 1. The heat dissipation fins 9 can increase the heat exchange area of ​​the housing 1, thereby improving the heat exchange efficiency of the housing 1. In this way, the temperature of the inner housing 2, i.e., the cold end, can be quickly reduced, which is beneficial for the thermoelectric conversion module 4 to establish a larger temperature difference and improve the thermoelectric conversion efficiency.

[0072] The specific material of the heat dissipation fins 9 is not limited. For example, the heat dissipation fins 9 can be made of high thermal conductivity materials such as steel, alloy, titanium alloy, carbon composite material, etc. to improve heat exchange efficiency.

[0073] For some examples, see Figure 3The heat-conducting column 7 includes a first connection surface 7a connected to the housing 1, and the heat-dissipating fin 9 includes a second connection surface 9a connected to the housing 1. The projection surface is a plane perpendicular to the top and bottom directions, and the projection of the second connection surface 9a is located within the projection range of the first connection surface 7a. In other words, the heat-conducting column 7 is aligned with the heat-dissipating fin 9, so that the heat can be smoothly and quickly transferred through the heat-conducting column 7 and the housing 1 to the heat-dissipating fin 9, and then the heat is dissipated.

[0074] For example, see Figure 2 There are multiple heat-conducting columns 7 and heat-dissipating fins 9, and each heat-conducting column 7 and the heat-dissipating fins 9 aligned therewith are respectively connected to both sides of the shell 1 along the thickness direction. In this way, the heat exchange efficiency can be further improved, which is beneficial for the thermoelectric conversion module 4 to establish a larger temperature difference and improve the thermoelectric conversion efficiency.

[0075] The isotope power supply device 10 provided in the embodiment of the present application is further described below in conjunction with specific embodiments:

[0076] Comparing the shielding body made of tungsten alloy in the related art and the shielding structure 5 made of metal lead in the present application, the inner shell 2, the shielding body and the shielding structure 5 are all cylindrical structures, the outer diameter of the inner shell 2 is 30cm (centimeter) and the height is 30cm, the outer diameter of the shielding body made of tungsten alloy is 50cm and the height is 50cm, and to achieve the same shielding effect, the outer diameter of the shielding structure 5 made of metal lead is 54cm and the height is 54cm. Furthermore, the weight of the shielding body made of tungsten alloy is 1489kg (kilogram), and the weight of the shielding structure 5 made of metal lead is 1162kg, and the weight reduction ratio of the latter is 22% relative to the former.

[0077] The cost of tungsten alloy is 1,000 yuan / kg, and the cost of metal lead is 20 yuan / kg. That is to say, the cost of the shielding body made of tungsten alloy is 1.489 million yuan, and the cost of the shielding structure 5 made of metal lead is 23,000 yuan. The latter saves 1.466 million yuan compared with the former, and the saving ratio is as high as 98.4%. In this way, the isotope power supply device 10 provided in the embodiment of the present application can greatly reduce the production cost, which is beneficial to the wide application of the isotope power supply device 10.

[0078] In the description of this specification, the description with reference to the terms "an embodiment", "some embodiments" and "exemplary" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0079] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction. The above description is only a preferred embodiment of this application and is not intended to limit this application. For those skilled in the art, this application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. An isotope power supply device, characterized in that: include: A housing forming a shielding cavity; An inner shell is formed with a containing cavity, the inner shell is arranged in the shielding cavity, and the inner shell is spaced apart from the wall surface of the shielding cavity; an isotope heat source, disposed in the containing chamber, the isotope heat source being spaced apart from a wall surface of the containing chamber; A thermoelectric conversion module is disposed in the accommodating cavity, and is used to convert the heat generated by the isotope heat source into electrical energy; The shielding structure fills the gap between the inner shell and the wall surface of the shielding cavity.

2. The isotope power supply device according to claim 1, characterized in that: The shielding structure includes a lead structure.

3. The isotope power supply device according to claim 1, characterized in that: The isotope power supply device comprises a heat-insulating component, and the heat-insulating component is arranged between the isotope heat source and the inner shell.

4. The isotope power supply device according to claim 3, characterized in that: The thermoelectric conversion module passes through the heat insulating member, and the thermoelectric conversion module contacts the isotope heat source and the inner shell.

5. The isotope power supply device according to claim 1, characterized in that: The isotope power supply device comprises a heat-conducting column located in the shielding cavity, and the heat-conducting column connects the inner shell and the outer shell.

6. The isotope power supply device according to claim 5, characterized in that: The length of the heat-conducting column is not less than the distance between the inner shell and the outer shell.

7. The isotope power supply device according to claim 5, characterized in that: The heat-conducting column extends along a curve.

8. The isotope power supply device according to claim 1, characterized in that: The isotope power supply device comprises a support column, which is arranged at the bottom of the inner shell and connects the inner shell and the outer shell.

9. The isotope power supply device according to claim 1, characterized in that: The isotope power supply device comprises heat dissipation fins, and the heat dissipation fins are connected to the outer surface of the shell.

10. The isotope power supply device according to claim 9, characterized in that: The isotope power supply device includes a heat-conducting column, the heat-conducting column includes a first connecting surface connected to the outer shell, and the heat dissipation fin includes a second connecting surface connected to the outer shell. The plane perpendicular to the top and bottom directions is used as the projection surface, and the projection of the second connecting surface is located within the projection range of the first connecting surface.

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