Free piston stirling generator

Abstract

The present disclosure relates to a kind of free piston stirling generator, including shell, valve piston, power piston and support rod;Shell has expansion cavity, compression cavity and buffer cavity in it, valve piston is located in the side of power piston, and the end of valve piston towards power piston forms compression cavity with power piston;Support rod and valve piston are located in the same side of power piston, and valve piston has passage, support rod is arranged in passage and forms sealing gap with the inner wall of passage, and elastic member is connected between support rod and the inner wall of passage, to support valve piston;The end face area of the end of valve piston towards power piston is less than the end face area of the end of valve piston away from power piston, to make valve piston move axially between expansion cavity and compression cavity under the action of pressure wave generated by power piston axial movement, to solve the problems of piston wear, unstable operation of generator, low efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of generator technology, and more particularly to a free piston Stirling generator. Background Technology

[0002] Due to the massive consumption of fossil fuels, the global energy crisis and environmental pollution are becoming increasingly serious. With the rise of renewable energy, not only energy itself but also the way energy is used is becoming increasingly important. As a new type of heat engine, the Stirling generator can utilize almost all existing heat sources, has high heat-to-work conversion efficiency, and boasts advantages such as high efficiency, long lifespan, low pollution, and low noise. It has found some successful applications in underwater propulsion, solar power, space station propulsion, and small-scale distributed energy.

[0003] The free piston Stirling generator is one type of Stirling generator. In existing free piston Stirling generators, a valve rod is installed on the valve piston. The valve rod passes through the power piston and is fixed to an elastic element on one side of the buffer chamber to achieve the support effect.

[0004] Because the valve train piston rod needs to pass through the power piston, the coaxial assembly of the valve train piston and the power piston during generator assembly requires high precision. If the assembly is not completely coaxial or under external forces, frictional losses and radial interaction forces will occur between the valve train piston rod and the power piston during generator operation, resulting in piston wear, generator instability, and low efficiency. Furthermore, this structure requires the power piston to form sealing gaps not only with the cylinder but also with the valve train piston rod. This increased sealing gap leads to increased leakage into the buffer chamber during periodic generator operation, resulting in decreased output efficiency. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this disclosure provides a free piston Stirling generator.

[0006] This disclosure provides a free piston Stirling generator, including a housing and a valve distribution piston, a power piston, and a support rod disposed within the housing;

[0007] The housing has an expansion chamber, a compression chamber and a buffer chamber arranged sequentially along the axial direction of the housing. The valve piston is located on one side of the power piston, and the compression chamber is formed between the end of the valve piston facing the power piston and the power piston.

[0008] The support rod and the valve piston are located on the same side of the power piston. The valve piston has a channel that extends through the valve piston along its axial direction. The support rod passes through the channel and forms a sealing gap with the inner wall of the channel. The support rod is connected to the housing, and an elastic element is connected between the support rod and the inner wall of the channel to support the valve piston.

[0009] The power piston can move axially between the compression chamber and the buffer chamber; the end face area of ​​the gas distribution piston facing the power piston is smaller than the end face area of ​​the gas distribution piston away from the power piston, so that the gas distribution piston can move axially between the expansion chamber and the compression chamber under the action of the pressure wave generated by the axial movement of the power piston.

[0010] Optionally, a receiving cavity is provided on the inner wall of the channel, and the elastic element is located in the receiving cavity.

[0011] Optionally, the receiving cavity is an annular receiving cavity arranged circumferentially along the inner wall of the channel;

[0012] The elastic element is a leaf spring, which has a through hole in the middle. The support rod passes through the through hole and is fixed relative to the wall of the through hole.

[0013] Optionally, in the direction from the expansion chamber to the compression chamber, the channel includes a first channel segment and a second channel segment connected in sequence; the inner diameter of the second channel segment is larger than the inner diameter of the first channel segment, so that the end face area of ​​the valve distribution piston facing the power piston is smaller than the end face area of ​​the valve distribution piston away from the power piston.

[0014] The support rod includes a first rod segment and a second rod segment connected to each other. The first rod segment is connected to the housing. The outer diameter of the second rod segment is larger than the outer diameter of the first rod segment. The first rod segment passes through the first channel segment and forms a sealing gap with the first channel segment. The second rod segment passes through the second channel segment and forms a sealing gap with the second channel segment.

[0015] Optionally, the elastic element is disposed between the inner wall of the second rod segment and the second channel segment.

[0016] Optionally, the end of the first rod segment furthest from the second rod segment is connected to the front wall of the housing. The first rod segment is a straight rod coaxial with the valve piston, and the axial length of the first rod segment accounts for 0.5 to 0.8 times the total length of the support rod.

[0017] Optionally, both the first and second segments are cylindrical segments;

[0018] Both the first channel segment and the second channel segment are cylindrical channel segments.

[0019] Optionally, a heater is provided on the inner wall of the housing corresponding to the position of the expansion cavity;

[0020] The gas distribution piston has a hollow structure, and a radiation shield is installed inside the gas distribution piston. The radiation shield is located on the side of the elastic element near the expansion cavity.

[0021] Optionally, there may be multiple radiation shields, which are arranged at intervals along the axial direction of the gas distribution piston.

[0022] Optionally, the radiation shield is a conical plate, with the larger end of the conical plate facing the elastic element.

[0023] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0024] The free-piston Stirling generator disclosed herein features a valve train piston positioned on one side of the power piston. A compression chamber is formed between the valve train piston and the power piston at the end facing the power piston. The support rod and valve train piston are located on the same side of the power piston. A channel is formed on the valve train piston, extending axially and penetrating the piston. The support rod, connected to the housing, passes through this channel, forming a sealing gap with the inner wall of the channel. An elastic element connects the support rod to the inner wall of the channel. The support rod and elastic element support the valve train piston. In other words, this configuration ensures that the valve train piston and power piston are positionally independent, their motion characteristics being coupled only through pressure waves, preventing mutual interference during movement. Compared to existing technologies, this fundamentally avoids piston wear and operational instability caused by contact forces between the valve train piston and power piston, improving the generator's operational reliability. Furthermore, even if the power piston and valve train piston are mounted on different axes, the lack of contact area between the two pistons prevents contact forces due to misalignment, thus reducing the coaxial assembly requirements of the power piston and valve train piston. Furthermore, this configuration ensures that the power piston forms a sealing gap only with the cylinder, which reduces the sealing gap between the power piston and the valve timing piston compared to existing technologies. In other words, it reduces one sealing gap, thereby reducing the periodic leakage to the buffer chamber during generator operation and thus improving the generator's output efficiency. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0026] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the free piston Stirling generator described in an embodiment of this disclosure.

[0028] Among them, 1. Shell; 101. Front shell; 102. Rear shell; 11. Expansion chamber; 12. Compression chamber; 13. Buffer chamber; 2. Gas distribution piston; 21. Channel; 211. First channel section; 212. Second channel section; 213. Receptacle; 3. Power piston; 4. Support rod; 41. First rod section; 42. Second rod section; 5. Elastic element; 6. Radiation shield; 71. Heater; 72. Regenerator; 73. Cooler; 8. Linear motor. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0030] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0031] Reference Figure 1 As shown, this embodiment provides a free piston Stirling generator, including: a housing 1, a valve piston 2, a power piston 3, a support rod 4, and a linear motor 8.

[0032] The gas distribution piston 2, the power piston 3, and the support rod 4 are all housed inside the housing 1. The housing 1 may specifically include a front housing 101 and a rear housing 102, and the housing 1 is filled with high-pressure helium gas.

[0033] The housing 1 has an expansion chamber 11, a compression chamber 12, and a buffer chamber 13 arranged sequentially along the axial direction of the housing 1. In a specific implementation, a heater 71, a regenerator 72, and a cooler 73 are also arranged sequentially on the inner wall of the housing 1, wherein the heater 71 corresponds to the expansion chamber 11. The heater 71, the regenerator 72, and the cooler 73 are all arranged symmetrically in a ring along the axis of the housing 1.

[0034] The valve timing piston 2 is located on one side of the power piston 3, and the end of the valve timing piston 2 facing the power piston 3 forms the compression chamber 12 between the two. Specifically, the end of the valve timing piston 2 away from the power piston 3 forms the expansion chamber 11 between the two and the housing 1. The linear motor 8 is correspondingly disposed within the rear housing 102 and corresponds to the buffer chamber 13. The power piston 3 can move axially between the compression chamber 12 and the buffer chamber 13 to drive the linear motor 8 to generate electricity.

[0035] The support rod 4 and the valve timing piston 2 are located on the same side of the power piston 3. The valve timing piston 2 has a channel 21, which is opened along the axial direction of the valve timing piston 2 and passes through the valve timing piston 2. The support rod 4 passes through the channel 21 and forms a sealing gap with the inner wall of the channel 21. The support rod 4 is connected to the housing 1, and an elastic element 5 is connected between the support rod 4 and the inner wall of the channel 21 to support the valve timing piston 2.

[0036] Reference Figure 1 As shown, the support rod 4 can be connected to the front wall of the front housing 101. Of course, in other implementations, the support rod 4 can also be connected to the top wall of the housing 1, as long as it can support the valve piston 2 and does not affect the axial movement of the valve piston 2.

[0037] The end face area of ​​the valve distribution piston 2 facing the power piston 3 is smaller than the end face area of ​​the valve distribution piston 2 away from the power piston 3, so that the valve distribution piston 2 moves axially between the expansion chamber 11 and the compression chamber 12 under the action of the pressure wave generated by the axial movement of the power piston 3.

[0038] Understandably, when the generator is running, the pressures in the expansion chamber 11 and the compression chamber 12 are approximately equal. Since the end face area of ​​the valve distribution piston 2 facing the power piston 3 is smaller than the end face area of ​​the valve distribution piston 2 away from the power piston 3, that is, the end face areas of the valve distribution piston 2 on the expansion chamber 11 and compression chamber 12 sides are not equal, the gas forces on the valve distribution piston 2 under the action of the pressure wave will not cancel each other out. As a result, the valve distribution piston 2 is subjected to gas forces under the action of the pressure wave and moves axially between the expansion chamber 11 and the compression chamber 12.

[0039] In other words, the power piston 3 and the valve train piston 2 are independent of each other in position, and their motion characteristics are coupled only through pressure waves. Their motion processes do not interfere with each other. Compared with existing technologies, this fundamentally avoids the problem of piston wear and operational instability caused by contact forces between the valve train piston 2 and the power piston 3, thus improving the operational reliability of the generator. Even if the power piston 3 and the valve train piston 2 are installed on different axes, the two piston components have no contact area, preventing contact forces caused by misalignment, thereby reducing the coaxial assembly requirements of the power piston 3 and the valve train piston 2.

[0040] Furthermore, during generator operation, the reciprocating motion of the power piston generates pressure waves in the working chambers (expansion chamber and compression chamber), while the pressure in the buffer chamber remains approximately constant. Within one cycle, a varying pressure difference exists between the compression chamber and the buffer chamber. Driven by this pressure difference, a mass flow rate is generated in the sealing gap between the compression chamber and the buffer chamber. This mass flow rate is related not only to the pressure difference between the working chamber and the buffer chamber but also to the sealing gap. The more sealing gaps there are, the greater the mass flow rate, the greater the periodic leakage of the generator, and the lower the output efficiency. In the free-piston Stirling generator provided in this embodiment, the power piston 3 only forms a sealing gap with the cylinder. Compared to related technologies, this reduces the sealing gap between the power piston 3 and the valve train piston 2, i.e., it reduces one sealing gap, thereby reducing the periodic leakage to the buffer chamber 13 during generator operation and improving the generator's output efficiency.

[0041] The free piston Stirling generator provided in this embodiment, by placing the valve distribution piston 2 on one side of the power piston 3, forms a compression chamber 12 between the end of the valve distribution piston 2 facing the power piston 3 and the power piston 3, and placing the support rod 4 and the valve distribution piston 2 on the same side of the power piston 3, a channel 21 is opened on the valve distribution piston 2, the channel 21 is opened along the axial direction of the valve distribution piston 2 and passes through the valve distribution piston 2, so that the support rod 4 connected to the housing 1 passes through the channel 21 and forms a sealing gap with the inner wall of the channel 21. An elastic element 5 is connected between the support rod 4 and the inner wall of the channel 21 to support the valve distribution piston 2. In other words, through the above arrangement, the valve distribution piston 2 and the power piston 3 are independent of each other in position, and their motion characteristics are coupled together only through pressure waves. The motion process will not interfere with each other. Compared with the prior art, it fundamentally avoids the problem of piston wear and unstable operation caused by the contact force between the valve distribution piston 2 and the power piston 3, and improves the operational reliability of the generator. Moreover, even if the power piston 3 and the valve train piston 2 are mounted on different shafts, this configuration eliminates contact forces caused by the misalignment due to the lack of contact area between the two pistons, thus reducing the coaxial assembly requirements of the power piston 3 and the valve train piston 2. Furthermore, this configuration ensures that the power piston 3 only forms a sealing gap with the cylinder, reducing the sealing gap between the power piston 3 and the valve train piston 2 compared to existing technologies. This reduction in sealing gaps decreases the periodic leakage to the buffer chamber 13 during generator operation, thereby improving the generator's output efficiency. This results in a highly reliable and efficient free-piston Stirling generator.

[0042] Continue to refer to Figure 1As shown, in a specific implementation, a receiving cavity 213 is provided on the inner wall of the channel 21, and the elastic element 5 is located in the receiving cavity 213. By providing the receiving cavity 213, the installation of the elastic element 5 can be facilitated, while further ensuring the sealing between the support rod 4 and the gas distribution piston 2, and ensuring the normal movement of the gas distribution piston 2.

[0043] In some embodiments, the accommodating cavity 213 is specifically an annular accommodating cavity 213 arranged circumferentially along the inner wall of the channel 21. The elastic element 5 is a leaf spring, with a through hole in its center. The support rod 4 passes through the through hole and is fixed relative to the wall of the through hole.

[0044] The leaf spring provides radial support to the entire circumference of the valve train piston 2, and also possesses axial elasticity, thus providing support in both the radial and axial directions. This further improves the operational stability of the valve train piston 2, thereby enhancing the reliability of the generator. Since the valve train piston 2 is supported by the support rod 4 and the leaf spring, and the lifespan of the leaf spring is currently very high, supporting the valve train piston 2 with the leaf spring further ensures the reliability and longevity of the generator.

[0045] The leaf spring may specifically include a base plate, which may be, for example, a circular base plate. A through hole is provided at the center of the base plate. Multiple circumferentially distributed helical arms are provided on the base plate. Specifically, a connecting portion may be provided on the outer edge of the base plate, allowing the leaf spring to be fixed in the receiving cavity 213 via the connecting portion. The leaf spring may be, for example, a scroll arm leaf spring. Of course, in other implementations, the leaf spring may also be a forward scroll arm leaf spring or other forms of leaf spring, as long as it can provide stable radial support force to the valve piston 2 and meet a certain axial support force.

[0046] It should be noted that in other implementations, the elastic element 5 can also be a column spring, with one end connected to the inner wall of the channel 21, such as the inner wall of the accommodating cavity 213, and the other end connected to the outer wall of the support rod 4. In this case, multiple column springs can be provided, and the multiple column springs are arranged at intervals along the circumference of the support rod 4.

[0047] Reference Figure 1 As shown, in some embodiments, in the direction from the expansion chamber 11 to the compression chamber 12, the channel 21 includes a first channel segment 211 and a second channel segment 212 connected in sequence. It is understood that the end of the first channel segment 211 near the expansion chamber 11 forms the expansion chamber 11 between the first channel segment 211 and the housing 1, and the compression chamber 12 is located between the end of the second channel segment 212 away from the first channel segment 211 and the power piston 3.

[0048] The inner diameter of the second channel section 212 is larger than the inner diameter of the first channel section 211, so that the end face area of ​​the valve piston 2 facing the power piston 3 is smaller than the end face area of ​​the valve piston 2 away from the power piston 3.

[0049] Accordingly, the support rod 4 includes a first rod segment 41 and a second rod segment 42 connected to each other. The end of the first rod segment 41 away from the second rod segment 42 is connected to the housing 1. The outer diameter of the second rod segment 42 is larger than the outer diameter of the first rod segment 41. The first rod segment 41 passes through the first channel segment 211 and forms a sealing gap with the first channel segment 211. The second rod segment 42 passes through the second channel segment 212 and forms a sealing gap with the second channel segment 212.

[0050] Of course, in other implementations, the rear end (the end facing the compression chamber 12) of the valve piston 2 can be made smaller than the front end (the end facing the expansion chamber 11) so that the area of ​​the rear end face is smaller than the area of ​​the front end face. For example, the outer diameter of the rear end of the valve piston 2 gradually decreases along the direction from the expansion chamber 11 to the compression chamber 12.

[0051] Specifically, the elastic element 5 is disposed between the inner wall of the second rod segment 42 and the second channel segment 212, ensuring that the connection point between the elastic element 5 and the support rod 4 and the housing 1 is not too close, thereby further improving the support effect of the support rod 4 and the elastic element 5 on the valve piston 2 and improving the stability of the valve piston 2. Correspondingly, the accommodating cavity 213 is disposed on the inner wall of the second channel segment 212.

[0052] In specific implementation, the end of the first rod segment 41 furthest from the second rod segment 42 is connected to the front wall of the housing 1. The first rod segment 41 is a straight rod coaxial with the valve piston 2. The axial length of the first rod segment 41 can be 0.5 to 0.8 times the total length of the support rod 4. Since a heater 71 is provided on the inner wall of the housing 1 corresponding to the expansion chamber 11, to avoid the heat emitted by the heater 71 affecting the elastic element 5, by setting the length of the first rod segment 41 within the aforementioned range, the distance between the elastic element 5 and the heater 71 can be further guaranteed, thus preventing the elastic element 5 from deforming or being damaged by heat, which would affect the support effect.

[0053] Specifically, the first rod segment 41 and the second rod segment 42 can both be cylindrical rod segments, and the first channel segment 211 and the second channel segment 212 can both be cylindrical channel segments.

[0054] In some embodiments, the gas distribution piston 2 can be configured as a hollow structure, and a radiation shield 6 is disposed inside the gas distribution piston 2. The radiation shield 6 is located on the side of the elastic member 5 near the expansion chamber 11. The radiation shield 6 provides heat insulation, which to a certain extent prevents the heat emitted by the heater 71 from being transferred to the elastic member 5, thus preventing the elastic member 5 from deforming or being damaged by heat and affecting its support performance.

[0055] In practice, multiple radiation shielding plates 6 can be configured, and these plates are arranged at intervals along the axial direction of the valve piston 2. Multi-stage heat insulation through multiple radiation shielding plates 6 further improves the heat insulation effect and provides better protection for the elastic element 5.

[0056] Additionally, refer to Figure 1 As shown, the radiation shielding plate 6 can be configured as a conical plate, with the larger end of the conical plate facing the elastic element 5. By configuring the radiation shielding plate 6 as a conical plate, the heat insulation area is increased without changing the internal cavity space of the valve piston 2, thereby further improving the heat insulation effect.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A free-piston Stirling generator, characterized in that, It includes a housing (1) and a gas distribution piston (2), a power piston (3) and a support rod (4) disposed within the housing (1); The housing (1) has an expansion chamber (11), a compression chamber (12) and a buffer chamber (13) arranged sequentially along the axial direction of the housing (1). The gas distribution piston (2) is located on one side of the power piston (3), and the compression chamber (12) is formed between the end of the gas distribution piston (2) facing the power piston (3) and the power piston (3). The support rod (4) and the valve piston (2) are located on the same side of the power piston (3). The valve piston (2) has a channel (21) that extends through the valve piston (2) along its axial direction. The support rod (4) passes through the channel (21) and forms a sealing gap with the inner wall of the channel (21). The support rod (4) is connected to the housing (1), and an elastic element (5) is connected between the support rod (4) and the inner wall of the channel (21) to support the valve piston (2). The power piston (3) can move axially between the compression chamber (12) and the buffer chamber (13); the end face area of ​​the gas distribution piston (2) facing the power piston (3) is smaller than the end face area of ​​the gas distribution piston (2) away from the power piston (3), so that the gas distribution piston (2) can move axially between the expansion chamber (11) and the compression chamber (12) under the action of the pressure wave generated by the axial movement of the power piston (3); In the direction along the expansion chamber (11) to the compression chamber (12), the channel (21) includes a first channel segment (211) and a second channel segment (212) connected in sequence; the inner diameter of the second channel segment (212) is larger than the inner diameter of the first channel segment (211) so that the end face area of ​​the valve piston (2) facing the power piston (3) is smaller than the end face area of ​​the valve piston (2) away from the power piston (3); The support rod (4) includes a first rod segment (41) and a second rod segment (42) connected to each other. The first rod segment (41) is connected to the housing (1). The outer diameter of the second rod segment (42) is larger than the outer diameter of the first rod segment (41). The first rod segment (41) passes through the first channel segment (211) and forms a sealing gap with the first channel segment (211). The second rod segment (42) passes through the second channel segment (212) and forms a sealing gap with the second channel segment (212). The elastic element (5) is disposed between the second rod segment (42) and the inner wall of the second channel segment (212); The end of the first rod segment (41) away from the second rod segment (42) is connected to the front wall of the housing (1). The first rod segment (41) is a straight rod coaxial with the gas distribution piston (2). The axial length of the first rod segment (41) is 0.5 to 0.8 times the total length of the support rod (4).

2. The free-piston Stirling generator according to claim 1, characterized in that, The inner wall of the channel (21) is provided with a receiving cavity (213), and the elastic element (5) is located in the receiving cavity (213).

3. The free-piston Stirling generator according to claim 2, characterized in that, The accommodating cavity (213) is an annular accommodating cavity arranged circumferentially along the inner wall of the channel (21); The elastic element (5) is a leaf spring, and the leaf spring has a through hole in the middle. The support rod (4) passes through the through hole and is fixed relative to the hole wall.

4. The free-piston Stirling generator according to claim 1, characterized in that, Both the first segment (41) and the second segment (42) are cylindrical segments; Both the first channel segment (211) and the second channel segment (212) are cylindrical channel segments.

5. The free-piston Stirling generator according to any one of claims 1 to 4, characterized in that, A heater (71) is provided on the inner wall of the housing (1) at the position corresponding to the expansion cavity (11). The gas distribution piston (2) has a hollow structure, and a radiation shield (6) is provided inside the gas distribution piston (2). The radiation shield (6) is located on the side of the elastic member (5) near the expansion cavity (11).

6. The free-piston Stirling generator according to claim 5, characterized in that, There are multiple radiation shielding plates (6), and the multiple radiation shielding plates (6) are arranged at intervals along the axial direction of the gas distribution piston (2).

7. The free-piston Stirling generator according to claim 5, characterized in that, The radiation shield (6) is a conical plate, with the large end of the conical plate facing the elastic member (5).

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