Compression pump of air conditioning system

Abstract

The utility model provides a compression pump of an air conditioning system, which comprises a cylinder body, at least one cylinder hole, at least one piston and at least one piston rod, a front cover connected to one end of the cylinder block; the rear cover is connected to the other end of the cylinder body; the first valve plate assembly is arranged between the cylinder body and the front cover; the second valve plate assembly is arranged between the cylinder body and the rear cover; the main shaft is rotatably arranged and penetrates through the air cylinder body, the first valve plate assembly and the second valve plate assembly; the inclined plate is fixedly connected to the main shaft and is designed to rotate along with the main shaft; and the piston is arranged in the cylinder hole of the cylinder body. The main shaft extends along the center line of the main shaft and is provided with a shaft core hole in the axial direction of the main shaft. The weight of the main shaft is directly reduced, energy consumption and vibration are reduced, the defects of high energy consumption, poor stability and the like caused by a solid main shaft in the prior art are overcome, and therefore the comprehensive performance and reliability of the compression pump of the air conditioning system are improved.

Description

Technical Field

[0001] This utility model relates to air compressors, and in particular to a compressor pump for an air conditioning system. Background Technology

[0002] Air conditioning systems are indispensable key equipment in modern life and industrial production, widely used in automobiles, construction, and home appliances. As the "heart" of the air conditioning system, the compressor pump is responsible for compressing and circulating the refrigerant, and its performance directly affects the efficiency, energy consumption, reliability, and user comfort of the entire system. Swashplate compressor pumps, due to their compact structure and adjustable displacement, are widely used in automotive air conditioning and other fields. With technological advancements and increasing environmental and energy-saving requirements, continuously optimizing the compressor pump structure to improve its operating efficiency, reduce energy consumption, decrease vibration and noise, and extend its service life has become an important direction for technological research and development in this field.

[0003] In the prior art, several technical solutions aimed at improving the performance of compressor pumps have been disclosed. For example, Chinese patent application CN101270740A discloses a "double-sided swashplate automotive compressor with a buffer mechanism and a method for suppressing its noise." This solution mainly reduces operating noise by setting a specific buffer mechanism inside the compressor. Specifically, it includes conventional components such as front and rear covers, front and rear cylinder blocks, thrust bearings, front and rear intake and exhaust springs, a sliding shoe, a swashplate, and a main shaft. A noise-reducing ring groove is formed on the swashplate (corresponding to the swashplate 40 in this application), and a noise-reducing ring is installed in the groove. At the same time, a specially designed noise-reducing piston (corresponding to the piston 41 in this application) is used. This piston is installed in the piston chamber and cooperates with the swashplate through the sliding shoe. This solution claims that through the synergistic effect of the noise-reducing ring and the noise-reducing piston, the collision between the piston and the swashplate can be reduced, thereby effectively reducing noise and reducing the friction between the swashplate and the piston neck, thus improving the service life of the compressor.

[0004] However, analysis revealed that while the technical solution disclosed in CN101270740A specifically addresses the noise problem caused by the collision between the piston and the swashplate, its technical approach mainly focuses on adding external buffer components (noise-reducing rings) and changing the piston structure, without optimizing the structure of the core rotating component of the compressor pump—the main shaft. In this prior art, the structure of the main shaft (corresponding to the main shaft 10 in this application) is not described in detail, but based on conventional design in this field and the lack of mention of any internal structural features, the main shaft should be a traditional solid shaft structure. This solid main shaft structure inherently has technical defects: First, as the main rotating component, the solid main shaft has a large mass, resulting in a high moment of inertia for the entire rotor system. During compressor startup, speed changes, and high-speed operation, driving such a heavy solid main shaft requires more energy, directly increasing the compressor's energy consumption and reducing overall operating efficiency. Secondly, the large rotating mass makes the spindle more susceptible to generating significant centrifugal force from even minor imbalances at high speeds. This can lead to vibrations throughout the compressor, affecting operational stability and potentially generating additional vibration noise. This, to some extent, negates the effect of the buffer mechanism in reducing collision noise. Furthermore, the solid structure of the spindle presents challenges for internal lubrication and cooling. Lubricating oil or cooling media cannot be directly and efficiently delivered through the spindle to critical friction or heat-generating components such as the spindle bearings and the connection between the swashplate and the spindle. This often necessitates complex external oil circuits or splash lubrication, which can result in insufficient lubrication or poor cooling, increasing component wear and limiting the compressor's reliability and durability under high load and high speed conditions.

[0005] Therefore, although the existing technology CN101270740A has made some improvements in suppressing specific noise sources, the problems inherent in its solid spindle structure, such as high energy consumption, poor stability, and difficulties in internal lubrication and cooling, remain unresolved, limiting further improvements in the overall performance of the compressor. How to overcome these shortcomings by optimizing the spindle's structure itself is a pressing technical problem in this field. Utility Model Content

[0006] The purpose of this invention is to provide a compressor pump for an air conditioning system to solve the problems of high energy consumption, poor stability, and difficulty in internal lubrication and cooling caused by the solid spindle structure of existing compressor pumps.

[0007] To achieve the above objectives, this utility model provides a compressor pump for an air conditioning system, comprising: a cylinder body with at least one cylinder bore inside; a front cover connected to one end of the cylinder body; a rear cover connected to the other end of the cylinder body; a first valve plate assembly disposed between the cylinder body and the front cover; a second valve plate assembly disposed between the cylinder body and the rear cover; a main shaft rotatably disposed and passing through the cylinder body, the first valve plate assembly, and the second valve plate assembly; an inclined plate fixedly connected to the main shaft and designed to rotate with the main shaft; and at least one piston disposed within the cylinder bore of the cylinder body and linked to the rotational movement of the inclined plate to perform reciprocating motion within the cylinder bore. The key feature is that the main shaft has a core hole extending along its own centerline and axially, the core hole penetrating at least one segment of the main shaft's length, thereby forming a hollow or partially hollow structure inside the main shaft.

[0008] A hollow structure is formed by creating a core hole in the center of the spindle. This structure firstly directly removes material from the central part of the spindle, significantly reducing its weight and moment of inertia. This helps reduce the energy consumption required to drive the spindle's rotation, thereby improving the overall operating efficiency of the compressor pump. Secondly, the hollow structure alters the mass distribution of the spindle, making it closer to an ideal axisymmetric state. This helps improve rotational balance, reducing vibration and noise caused by mass imbalance during high-speed rotation, and enhancing operational stability. Furthermore, the core hole provides a potential channel space inside the spindle, laying the structural foundation for subsequent internal lubrication and cooling. Simultaneously, removing the central material may also help release residual manufacturing stress and optimize the distribution of working stress, potentially positively impacting the spindle's fatigue life and durability while ensuring necessary strength.

[0009] Preferably, the spindle bore is located on the centerline of the spindle and extends axially along the spindle, with its extension covering at least the middle section of the spindle where the swashplate is mounted and the sections adjacent to both ends of the spindle. In this way, the spindle bore defines an internal channel space that runs through the critical working area of ​​the spindle and extends to both ends.

[0010] The spindle core hole is located on the spindle rotation center line and extends axially to cover the critical area, ensuring that the formed internal channel space can effectively serve the critical parts of the spindle that require lubrication or cooling. This provides the necessary structural prerequisites and path guarantee for the subsequent use of this channel to achieve efficient internal lubrication and cooling functions.

[0011] Preferably, at least one radial hole is further formed on the spindle. This radial hole extends radially outward from the internal channel space defined by the spindle core hole and ultimately opens onto the outer cylindrical surface of the spindle. Structurally, this radial hole connects the spindle core hole to the outside of the spindle.

[0012] By adding a radial hole leading from the spindle core hole to the outer surface of the spindle, a physical connection is established between the internal channel and the outside of the spindle. This solves the problem that fluid cannot effectively reach the outside due to the presence of only a spindle core hole. It allows lubricating oil or cooling medium in the internal channel to be guided through the radial hole to the outer surface of the spindle or specific components in contact with the outer surface of the spindle (such as bearings, swashplate contact surfaces, etc.), thereby realizing the possibility of point-to-point lubrication or cooling. This is a key structure for the concrete realization of the internal lubrication / cooling function.

[0013] Preferably, the core hole has a non-circular cross-sectional shape; specifically, its cross-section is elliptical, having a major axis and a minor axis. Furthermore, the opening location of at least one radial hole on the inner wall of the elliptical core hole is adjacent to the endpoint region of the major axis of the ellipse.

[0014] The use of an elliptical core bore cross-section alters the stress concentration characteristics at the bore edge, providing design possibilities for strength optimization under specific loads. Furthermore, during high-speed spindle rotation, the fluid within the elliptical bore, subjected to centrifugal force, may be more easily propelled towards the ends of the longer shaft. Positioning the inner opening of the radial bore near the endpoints of the elliptical longer shaft leverages this potential hydrodynamic characteristic, enhancing the directional flow and distribution of fluid towards that specific radial bore, potentially improving lubrication or cooling of critical components targeted by the bore.

[0015] Preferably, the spindle includes a front end section adjacent to the front cover and the first valve plate assembly, and a rear end section adjacent to the rear cover and the second valve plate assembly. The elliptical spindle hole is completely disposed through the spindle along the spindle axis, with one end opening in the front end section of the spindle and the other end opening in the rear end section of the spindle, thereby forming a through-hole structure that runs through the entire spindle.

[0016] Designing the elliptical spindle core hole as a through-hole structure extending through both ends of the spindle firstly greatly simplifies the manufacturing process. For example, drilling and honing can be completed in one step, ensuring the straightness and surface quality of the hole. Secondly, the through-hole structure facilitates subsequent internal inspections (such as dimensional measurement and flaw detection) and post-machining cleaning, reducing manufacturing costs and quality control difficulties. Furthermore, the openings at both ends of the spindle provide possibilities for functional expansion, such as mounting sensors or other accessories at the ports.

[0017] Preferably, the at least one radial hole extends substantially in a radial direction perpendicular to the spindle centerline, originating from the inner wall of the elliptical spindle hole near the end of the major axis, to the outer cylindrical surface of the spindle. Furthermore, the opening size of the radial hole at its outer end, where it opens onto the outer cylindrical surface of the spindle, is designed to be significantly smaller than the minor axis length of the elliptical spindle hole's cross-section.

[0018] The radial bore is further defined to extend substantially in the radial direction, ensuring that fluid can be directly delivered to the circumferential surface of the spindle or adjacent components. Simultaneously, the smaller size of its outer end opening (significantly smaller than the spindle bore size) acts as a throttling mechanism, helping to precisely control the amount of fluid flowing to specific lubrication or cooling points, avoiding waste or insufficient supply, and thus more effectively achieving targeted and quantitative lubrication and cooling.

[0019] In summary, this invention fundamentally changes the structure of traditional solid spindles by opening a core hole at the center of the compressor pump spindle and selectively combining it with radial holes and specific hole designs. This not only directly reduces the weight of the spindle, lowers energy consumption and vibration, but also overcomes the defects of high energy consumption and poor stability caused by solid spindles in the prior art, thereby improving the overall performance and reliability of the air conditioning system compressor pump. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the air conditioning system compressor pump according to one embodiment of the present invention.

[0021] Figure 2 This is a structural schematic diagram of the cross-section of the core hole according to another embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model.

[0023] Reference Figure 1 The diagram shows a structural schematic of an air conditioning system compressor pump 100 according to an embodiment of the present invention. (Refer to...) Figure 2 The diagram shows a cross-sectional view of the spindle core hole 11 in the spindle 10 according to another embodiment of the present invention.

[0024] This utility model provides a compressor pump 100 for an air conditioning system, such as... Figure 1 As shown, it includes: a cylinder body 70, the cylinder body 70 having at least one cylinder bore inside; and a front cover 20, connected to one end of the cylinder body 70. Figure 1 Left side); rear cover 30, connected to the other end of the cylinder block 70 ( Figure 1(Right side); First valve plate assembly 51, disposed between the cylinder body 70 and the front cover 20; Second valve plate assembly 52, disposed between the cylinder body 70 and the rear cover 30; Main shaft 10, rotatably disposed and passing through the cylinder body 70, the first valve plate assembly 51 and the second valve plate assembly 52; Inclined plate 40, fixedly connected to the main shaft 10 and designed to rotate with the main shaft 10; At least one piston 41, disposed in the cylinder bore of the cylinder body 70 and linked with the rotational movement of the inclined plate 40 to reciprocate within the cylinder bore. The key feature is that the main shaft 10 has a core hole 11 extending along its own centerline and axially, the core hole 11 penetrating at least one section of the length of the main shaft 10, thereby forming a hollow or partially hollow structure inside the main shaft 10.

[0025] A hollow structure is formed by creating a core hole 11 at the center of the spindle 10. This structure firstly directly removes material from the central part of the spindle 10, significantly reducing its own weight and moment of inertia. This helps reduce the energy consumption required to drive the spindle 10's rotation, thereby improving the overall operating efficiency of the compression pump 100. Secondly, the hollow structure alters the mass distribution of the spindle 10, making it closer to an ideal axisymmetric state. This helps improve rotational balance, reduces vibration and noise during high-speed rotation caused by mass imbalance, and enhances operational stability. Furthermore, the formation of the core hole 11 provides a potential channel space inside the spindle 10, laying the structural foundation for subsequent internal lubrication and internal cooling. Simultaneously, removing the central material may also help release residual manufacturing stress and optimize the working stress distribution, potentially positively impacting the fatigue life and durability of the spindle 10 while ensuring necessary strength.

[0026] In a preferred embodiment of this invention, such as Figure 1 As shown, the spindle core hole 11 is located on the center line of the spindle 10 and extends along the axial direction of the spindle 10. Its extension range covers at least the middle section of the spindle 10 where the inclined plate 40 is installed and the sections adjacent to both ends of the spindle 10. In this way, the spindle core hole 11 defines an internal channel space that runs through the key working area of ​​the spindle 10 and extends to both ends.

[0027] The spindle core hole 11 is located on the rotation center line of the spindle 10 (minimizing the impact on balance) and extends axially to cover the critical areas (the central inclined plate 40 area and the bearing areas at both ends), ensuring that the formed internal channel space can effectively serve the critical parts of the spindle 10 that require lubrication or cooling, providing the necessary structural prerequisites and path guarantees for the subsequent use of this channel to achieve efficient internal lubrication and cooling functions.

[0028] Furthermore, such as Figure 2As shown, at least one radial hole 12 is further formed on the spindle 10. The radial hole 12 extends radially outward from the internal channel space defined by the spindle core hole 11 and finally opens at the outer cylindrical surface of the spindle 10. Structurally, the radial hole 12 connects the spindle core hole 11 to the outside of the spindle 10.

[0029] By adding a radial hole 12 leading from the spindle core hole 11 to the outer surface of the spindle 10, a physical connection is established between the internal channel and the outside of the spindle 10. This solves the problem that fluid cannot effectively reach the outside due to the spindle core hole 11 alone. It allows the lubricating oil or cooling medium in the internal channel to be guided through the radial hole 12 to the outer surface of the spindle 10 or specific components in contact with the outer surface of the spindle 10, such as bearings or inclined plate contact surfaces. This enables point-to-point lubrication or cooling and is a key structure for the concrete realization of the internal lubrication / cooling function.

[0030] In particular, such as Figure 2 As shown, the core hole 11 has a non-circular cross-sectional shape; specifically, its cross-section is elliptical, with a major axis and a minor axis. Furthermore, at least one radial hole 12 is positioned on the inner wall of the elliptical core hole 11 at an end region adjacent to the major axis of the ellipse.

[0031] The use of an elliptical cross-section for the spindle bore 11 alters the stress concentration characteristics at the bore edge, providing design possibilities for strength optimization under specific loads. Furthermore, during high-speed rotation of the spindle 10, the fluid within the elliptical bore 11, subjected to centrifugal force, may be more easily propelled towards both ends of the long shaft. Positioning the inner opening of the radial bore 12 near the endpoints of the elliptical long shaft leverages this potential hydrodynamic characteristic, enhancing the directional flow and distribution of fluid to that specific radial bore 12, potentially improving lubrication or cooling of critical components pointed to by the radial bore 12.

[0032] like Figure 1 As shown, in this embodiment, the main shaft 10 includes a front end section adjacent to the front cover 20 and the first valve plate assembly 51, and a rear end section adjacent to the rear cover 30 and the second valve plate assembly 52. ​​The elliptical shaft core hole 11 is completely through the main shaft 10 along its axial direction, with one end opening in the front end section of the main shaft 10 and the other end opening in the rear end section of the main shaft 10, thereby forming a through-hole structure that runs through the entire main shaft 10.

[0033] Designing the elliptical spindle core hole 11 as a through-hole structure penetrating both ends of the spindle 10 firstly greatly simplifies the manufacturing process. For example, drilling and honing can be completed in one operation, ensuring the straightness and surface quality of the hole. Secondly, the through-hole structure facilitates subsequent internal inspections (such as dimensional measurement and flaw detection) and post-machining cleaning, reducing manufacturing costs and quality control difficulties. Furthermore, the openings at both ends of the spindle 10 provide possibilities for functional expansion, such as mounting sensors or other accessories at the ports.

[0034] Furthermore, such as Figure 2 As shown, the at least one radial hole 12 extends from the inner wall of the elliptical spindle hole 11 near the end of the major axis, and extends substantially in a radial direction perpendicular to the center line of the main shaft 10, to the outer cylindrical surface of the main shaft 10. Furthermore, the opening size of the radial hole 12 at its outer end opening onto the outer cylindrical surface of the main shaft 10 is designed to be significantly smaller than the minor axis length of the cross-section of the elliptical spindle hole 11.

[0035] The radial hole 12 extends substantially in the radial direction, ensuring that fluid can be directly delivered to the circumferential surface of the spindle 10 or adjacent components. At the same time, the outer end opening size is designed to be small (significantly smaller than the size of the spindle hole 11), which acts as a throttling mechanism, helping to precisely control the amount of fluid flowing out to specific lubrication or cooling points, avoiding waste or insufficient supply, and thus achieving more effective point-to-point and quantitative lubrication and cooling.

[0036] Specifically, in this embodiment, such as Figure 1 and Figure 2 As shown, the air conditioning system compressor pump 100 belongs to the compressor technology category in the field of refrigeration and air conditioning technology, specifically the structure of an air conditioning system compressor pump. Its core component, the main shaft 10, is a key rotating part of the compressor pump. It is a slender cylindrical shape that penetrates the center of the cylinder body 70, with its two ends near the front cover 20 and the rear cover 30, respectively. The innovation of this main shaft 10 lies in the centrally located shaft core hole 11. This shaft core hole 11 is positioned along the centerline of the main shaft 10, according to… Figure 2 As shown, its cross-section can be non-circular, such as the ellipse shown in the figure, and extends a considerable distance along the axial direction of the spindle 10, forming an internal fluid channel and achieving weight reduction of the spindle 10. The dimensions of the spindle bore 11 are determined while ensuring the necessary strength of the spindle 10. In order to distribute the fluid (such as lubricating oil / cooling medium) within the spindle bore 11, at least one radial hole 12 is also provided on the spindle 10. Figure 2 The radial hole 12 extends from the inner wall near the end of the long axis of the elliptical spindle hole 11 and leads to the outer surface of the spindle 10, forming a relatively small channel for precisely delivering fluid to the location where lubrication or cooling is required.

[0037] A swashplate 40 is fixedly mounted in the middle of the spindle 10. The swashplate 40 is an annular part with its outer edge surface inclined relative to the axis of the spindle 10, used to convert the rotational motion of the spindle 10 into the reciprocating motion of the piston 41. The connection between the spindle 10 and the swashplate 40 needs to be reliable, which can be achieved through press fitting or integrated design.

[0038] Piston 41 according to Figure 1 As shown, the piston 41, shaped like a cup or a short plunger, is arranged within the cylinder bore of the cylinder block 70. Its internal structure is used to connect with a transmission mechanism (such as a slide), and it reciprocates within the cylinder bore under the drive of the swashplate 40, thereby changing the cylinder's working volume to compress the refrigerant. The stroke of the piston 41 is determined by the angle of the swashplate 40.

[0039] The cylinder block 70 is the main structure of the compression pump 100, containing a cylinder bore to accommodate the movement of the piston 41, and a through hole in the center for the main shaft 10 to pass through. The front end of the cylinder block 70 ( Figure 1 Left side) connects to front cover 20, rear end ( Figure 1 (Right side) Connect the back cover 30.

[0040] The front cover 20 and the rear cover 30 respectively enclose the two ends of the cylinder block 70 and may contain bearing structures that support the rotation of the main shaft 10. A clutch 60 is usually connected to the outside of the front cover 20 for transmitting or disconnecting external power.

[0041] A first valve plate assembly 51 is disposed between the cylinder block 70 and the front cover 20, and a second valve plate assembly 52 is disposed between the cylinder block 70 and the rear cover 30. Both valve plate assemblies are plate-shaped structures containing valve structures that control gas flow, through which the main shaft 10 passes. The first valve plate assembly 51 is adjacent to the front cover 20, and the second valve plate assembly 52 is adjacent to the rear cover 30. These components together constitute the housing and internal working mechanism of the compression pump.

[0042] Through the above structural design, the air conditioning system compressor pump 100 of this utility model utilizes a main shaft 10 structure with a shaft core hole 11 and a radial hole 12, which effectively reduces weight, lowers energy consumption, improves rotational stability, and provides efficient lubrication and cooling channels for internal key components, thereby comprehensively improving the performance, reliability and service life of the compressor pump.

[0043] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An air conditioning system compressor pump (100) characterized by, The utility model relates to a cylinder block (70) inside is equipped with at least one cylinder hole, front cover (20) is connected to one end of cylinder block (70), rear cover (30) is connected to the other end of cylinder block (70), first valve plate assembly (51) is arranged between cylinder block (70) and front cover (20), second valve plate assembly (52) is arranged between cylinder block (70) and rear cover (30), main shaft (10) rotatably arranged and passes through cylinder block (70), first valve plate assembly (51) and second valve plate assembly (52), cam plate (40) is fixedly connected on main shaft (10) and is designed as rotating with main shaft (10), at least one piston (41) is arranged in cylinder hole of cylinder block (70) and is linked with the rotation of cam plate (40) to carry out reciprocating motion in cylinder hole, wherein main shaft (10) is opened with a shaft core hole (11) along its own center line and along its axial extension, and the shaft core hole (11) passes through at least one section of the length of main shaft (10), thereby forming a hollow or partially hollow structure inside main shaft (10). The shaft core hole (11) is located on the center line of the main shaft (10) and extends in the axial direction of the main shaft (10) to cover at least the middle section of the main shaft (10) where the cam plate (40) is located and the sections adjacent to both ends of the main shaft (10), and the shaft core hole (11) defines an internal passage space extending along the main shaft (10). The main shaft (10) is further provided with at least one radial hole (12) extending radially outward from the internal passage space defined by the shaft core hole (11) and opening to the outer cylindrical surface of the main shaft (10), and the radial hole (12) structurally communicates the shaft core hole (11) with the outside of the main shaft (10). The shaft core hole (11) has a non-circular cross-sectional shape; the cross-section of the shaft core hole (11) is elliptical, the ellipse has a major axis and a minor axis; the inner end opening of the at least one radial hole (12) is located on the inner wall of the shaft core hole (11) of the ellipse, and the inner end opening is located adjacent to the long axis end point area of the ellipse. The main shaft (10) includes a front end section adjacent to the front cover (20) and the first valve plate assembly (51), and a rear end section adjacent to the rear cover (30) and the second valve plate assembly (52); the elliptical shaft core hole (11) is arranged in the axial direction of the main shaft (10) and opens at one end of the front end section of the main shaft (10) and at the other end of the rear end section of the main shaft (10), forming a through hole through the main shaft (10). ​ ​ ​ ​ ​ 2. The air conditioning system compression pump (100) as claimed in claim 1, wherein, ​ 3. The air conditioning system compression pump (100) of claim 2, wherein, ​ 4. The air conditioning system compression pump (100) of claim 3, wherein, ​ 5. The air conditioning system compression pump (100) as claimed in claim 4, wherein, ​ 6. The air conditioning system compression pump (100) of claim 5, wherein, The at least one radial hole (12) extends from the inner wall position of the elliptical shaft core hole (11) adjacent to the long axis end point to the outer cylindrical surface of the main shaft (10) in a radial direction perpendicular to the center line of the main shaft (10); the radial hole (12) is opened at the outer end of the outer cylindrical surface of the main shaft (10), and the opening size is smaller than the length of the short axis of the cross section of the elliptical shaft core hole (11).

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