An oil-free air compressor

Abstract

The present invention provides an oil-free air compressor, which belongs to the technical field of air compressors. It solves the problem that the existing oil-free air compressors are not stable enough. The oil-free air compressor includes a motor, a crankcase fixed on the motor, and a fan connected to the crankcase through a fan shaft. The motor shaft of the motor extends into the crankcase, and a parallel and eccentrically arranged crankshaft is fixedly connected to the end of the motor shaft. The fan shaft and the motor shaft have the same axis line. A connecting piece that can fix the motor shaft and the fan shaft circumferentially is connected between the fan shaft and the crankshaft. The connecting piece is fixed circumferentially to the fan shaft, and in the vertical connection direction of the motor shaft and the crankshaft, the connecting piece and at least one of the fan shaft and the crankshaft are slidably matched. The operation of the oil-free air compressor is more stable and the service life is longer.

Description

Technical Field

[0001] The invention belongs to the technical field of air compressors and relates to an oil-free air compressor. Background Art

[0002] Oil-free air compressor is a miniature reciprocating piston compressor. When the motor drives the compressor crankshaft to rotate, the self-lubricating piston without adding any lubricant will reciprocate through the transmission of the connecting rod, and the working volume formed by the inner wall of the cylinder, the cylinder head and the top surface of the piston will change periodically. Oil-free air compressors are divided into 2V, 3Y, 4V, 6Y and other models according to the number of cylinders. 2V means that one end of the motor has 2 cylinders, 3Y means that one end of the motor has 3 cylinders, 4V means that both ends of the motor have 2 cylinders, and 6Y means that both ends of the motor have 3 cylinders. When the number of cylinders of the air compressor is large or the requirement for the exhaust volume is low, the installation structure in the comparative document (application number: 201410105649.X) and the comparative document (application number: 201610489352.7) is usually adopted, that is, an eccentric wheel is sleeved on the motor shaft of the motor, and the connecting rod of the piston is sleeved on the eccentric wheel. Of course, this structure does not require a crankshaft, so the end of the motor shaft is directly connected to the center position of the fan blade, so that the fan blade and the motor shaft have good coaxiality, and the rotation of the fan blade is also relatively stable.

[0003] However, when the number of cylinders of the air compressor is small and the exhaust volume requirement is high, it is necessary to increase the exhaust volume of the cylinder, so it is necessary to increase the stroke of the piston, that is, it is necessary to increase the eccentric distance of the eccentric wheel, but a bearing structure with a larger diameter is also provided between the connecting rod and the eccentric wheel, so that the use of an eccentric wheel connection will cause the volume of the air compressor to be too large. Therefore, when the number of cylinders at one or both ends of the air compressor is small, such as 2V and 4V model air compressors, and the exhaust volume requirement is high, a crankshaft structure needs to be adopted. In this case, the crankshaft structure in the comparative documents (application number: 201520878040.6), (application number: 201520441903.3) and (application number: 201510935279.7) needs to be adopted, that is, the crankshaft is connected to the motor shaft of the motor, and the connecting rod of the piston is directly mounted on the crankshaft. However, as shown in the above-mentioned comparative documents, after using a crankshaft, the fan blades need to be fixed at the end of the crankshaft. Therefore, the crankshafts in the above-mentioned comparative documents are all fixed to the eccentric position of the fan blades. This structure makes it difficult to ensure the coaxiality of the fan blades and the motor shaft when the fan blades are installed, and the fan blades are prone to instability during long-term use.

[0004] In response to the problem of unstable rotation of fan blades after adopting the crankshaft, the patent document (application number: 201710561966.6) discloses an oil-free air compressor, in which an eccentrically arranged crankshaft is fixedly connected to the end of the motor shaft, and an eccentric shaft is fixedly connected to the end of the crankshaft. The eccentric shaft and the motor shaft have the same axis line, and one end of the eccentric shaft extends out of the end face of the crankcase. The fan blades are arranged on the outside of the crankcase, and the end of the eccentric shaft is fixedly connected to the center position of the fan blade, that is, the fan blade is fixedly connected to the crankshaft through the eccentric shaft, so that the fan blade and the motor shaft are coaxial, but the eccentric shaft is positioned on the crankcase through a bearing, and the motor is also fixed on the crankcase, and the two are connected through the crankshaft and the eccentric shaft. Fixed connection requires that the eccentric distance between the crankshaft and the motor shaft is completely consistent with the eccentric distance of the eccentric shaft. At the same time, since the eccentric shaft is installed on the crankcase cover and the motor is fixed on the crankcase body, it is difficult to ensure that the motor shaft and the eccentric shaft have absolute coaxiality after the cover and the body are assembled. When there is a slight deviation in the coaxiality of the two, the circular trajectory of the crankshaft is concentric with the motor shaft during operation, and therefore it is difficult to be concentric with the fan blades. At this time, the crankshaft will generate radial push-pull forces on the fixedly connected eccentric shaft. The push-pull forces will cause excessive wear of the bearings on which the eccentric shaft is installed, and further cause radial shaking of the eccentric shaft, thereby affecting the operating stability of the fan blades and reducing their service life. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems in the prior art and to provide an oil-free air compressor, which has more stable operation and longer service life.

[0006] The objective of the present invention can be achieved through the following technical solutions: an oil-free air compressor, comprising a motor, a crankcase fixed on the motor, and a fan blade rotatably connected to the crankcase through a fan blade shaft, the motor shaft of the motor extends into the crankcase, and a parallel and eccentrically arranged crankshaft is fixedly connected to the end of the motor shaft, the fan blade shaft and the motor shaft have the same axial centerline, and a connecting piece that can circumferentially fix the motor shaft and the fan blade shaft is connected between the fan blade shaft and the crankshaft, characterized in that the connecting piece is circumferentially fixed to the fan blade shaft, and in the direction of the vertical connection between the motor shaft and the crankshaft, the connecting piece slides with at least one of the fan blade shaft and the crankshaft.

[0007] When there is one crankcase, it is fixed at one end of the motor. When there are two crankcases, they are symmetrically fixed at both ends of the motor. When the motor starts, it drives the crankshaft to rotate to realize the operation of the air compressor. At the same time, the connecting piece is connected between the fan shaft and the crankshaft, which can make the fan shaft and the motor shaft circumferentially fixed, so that the fan blade can be driven to rotate, thereby dissipating heat from the motor and the crankcase. The fan shaft is directly connected to the crankcase. When the coaxiality of the motor shaft and the fan shaft has a slight deviation during assembly, the circular trajectory of the end of the crankshaft during operation is concentric with the motor shaft, so it is difficult to ensure that the circular trajectory of the end of the crankshaft is concentric with the fan shaft. For this reason, the connecting piece can slide relative to at least one of the fan shaft and the crankshaft when connecting the crankshaft and the fan shaft. This is different from the traditional setting of a swing arm, in which the two ends of the swing arm are respectively fixed to the crankshaft and the fan shaft. The present invention relates to a fixed connection in which the eccentric rotation of the crankshaft and the fan blade shaft causes the swing arm to generate a radial push-pull force on the fan blade shaft. Compared with the fixed connection, the eccentric rotation of the crankshaft and the fan blade shaft causes the swing arm to generate a radial push-pull force on the fan blade shaft. The present connecting piece can slide and adjust relative to the crankshaft or the fan blade shaft during operation to eliminate the radial push-pull force on the fan blade shaft, thereby avoiding excessive wear of the bearings, seals and other components between the fan blade shaft and the crankcase during long-term use, as well as unstable phenomena such as shaking of the fan blade shaft, so that the fan blade shaft can operate stably and thus increase its service life. Of course, due to the sliding design of the connecting piece, this is different from the traditional fixed connection between the crankshaft and the fan blade shaft through a swing arm, which requires that the length of the swing arm be exactly equal to the vertical distance from the motor shaft to the crankshaft. The present air compressor has lower requirements on the coaxiality of the motor shaft and the fan blade shaft and the accuracy of the connecting piece between the crankshaft and the fan blade shaft during assembly, making assembly more convenient and reducing production costs.

[0008] In the above oil-free air compressor, the connecting member includes a long strip connecting plate, the connecting plate is vertically fixedly connected to the fan shaft, and the connecting plate is arranged along the vertical connection direction of the motor shaft and the crankshaft, and the crankshaft is slidably connected to the connecting plate along the length direction of the connecting plate. The connecting member adopts a long strip connecting plate to simplify the structure and reduce the load of the fan shaft rotation. At the same time, the connection method between the crankshaft and the connecting plate is diverse, so as to better realize the sliding fit between the connecting plate and the crankshaft.

[0009] In the above-mentioned oil-free air compressor, the connecting plate has a long strip-shaped notch arranged along the length direction, and the notch faces the crankshaft. The end of the crankshaft is vertically fixed with a rigid connecting strip, and the length direction of the connecting strip is consistent with the length direction of the connecting plate, and the connecting strip is inserted into the notch. The connecting strip and the connecting plate are both in the shape of long strips, so the mating surface between the connecting strip and the connecting plate is also in the shape of long strips. At this time, the crankshaft transmits power to the connecting strip, and the connecting strip can distribute the power to the entire connecting plate along the length direction, rather than the connecting plate being locally stressed. Therefore, the use of the notch matching between the connecting strip and the connecting plate can make the relative sliding between the connecting strip and the connecting plate smoother and more stable, and can also avoid excessive wear at the working position of the connecting plate and the crankshaft. Of course, the matching between the connecting strip and the connecting plate is also more stable.

[0010] In the above-mentioned oil-free air compressor, the connecting plate includes a long strip bottom plate, and both edges of the bottom plate have a row of limit plates, and the above-mentioned notch is formed between the two rows of limit plates. The edges of the bottom plate have elastic plates between two adjacent limit plates, and the two rows of elastic plates are relatively close and inclined and pressed against the opposite side surfaces of the connecting strip. The connecting strip is located between the two rows of limit plates, and the limit plates can ensure that the connecting strip does not detach to ensure the stability of the structure, and the elastic plates have an inward elastic pressure acting on the connecting strip, that is, the connecting strip is clamped by the elastic plates, so that while ensuring that the connecting strip and the connecting plate can slide relative to each other, the matching between the connecting strip and the connecting plate is made more compact, and the movement in the width direction between the connecting strip and the connecting plate is avoided.

[0011] In the above-mentioned oil-free air compressor, the connecting plate and the fan blade shaft are an integrated structure, a connecting hole is opened on the side of the connecting strip, a through hole is opened on the bottom surface of the connecting hole, and a supporting convex edge is arranged around the hole opening at one end of the through hole on the bottom surface of the connecting hole, and the hole opening at the other end of the through hole has a conical expansion in the circumference, and the conical surface of the expansion is opposite to the supporting convex edge, the end of the crankshaft is inserted into the connecting hole and fixedly connected by screws passing through the through hole, and the supporting convex edge is pressed against the end face of the crankshaft under the action of the screws. Since the force of the connecting strip on the connecting plate is basically distributed at a position deviating from the center of the fan blade shaft, the connecting plate and the fan blade shaft need to be circumferentially fixed to prevent the connecting plate from rotating relative to the fan blade shaft. For this reason, the connecting plate and the fan blade shaft adopt an integrated structure to ensure the stability between the two, while the connecting strip and the crankshaft adopt a structure that is separated and fixed by screws. The purpose is to ensure operational stability and assembly convenience. Specifically, since the connecting plate and the fan blade shaft are integrated, the position of the connecting plate is fixed after the fan blade shaft is assembled to the crankcase, and the position of the crankshaft is limited by core components such as the piston and the connecting rod, so the position is also fixed. At this time, after the connecting strip is fixed, the relative position accuracy between the connecting strip and the connecting plate is relatively high. For this reason, an abutting convex edge is provided at one end of the through hole, and a conical flared opening is provided at the other end, so that the solid part between the conical flared opening and the abutting convex edge forms a thin-walled structure. The thin-walled structure can be slightly deformed by the looseness of the screws, so that the relative position between the connecting strip and the connecting plate can be adjusted, thereby reducing the difficulty of assembly and improving the position accuracy between the connecting strip and the connecting plate, that is, ensuring operational stability.

[0012] In the above-mentioned oil-free air compressor, the connecting plate is symmetrically arranged relative to the axis of the fan blade shaft, and a number of symmetrically arranged counterweight holes are opened on the two opposite sides of the bottom plate. The traditional crankshaft and the fan blade shaft are fixedly connected by a swing arm. At this time, although the fan blade shaft will be subjected to the radial force of the swing arm, the fan blade shaft can also be positioned by the swing arm. This is also the reason why the traditional fan blade shaft and the crankshaft adopt a fixed hard connection. However, the connecting strip and the connecting plate of the present application can slide relative to each other, that is, the fan blade shaft is only positioned by the bearing. For this reason, the connecting plates are symmetrically arranged so that the fan blade shaft is evenly stressed when rotating. This is also consistent with the purpose of the connecting plate and the connecting strip being in the shape of long strips. At the same time, combined with the counterweight holes on the connecting plate, the force on the fan blade shaft is ensured to be as uniform as possible, so that its operation is stable.

[0013] In the above oil-free air compressor, the length of the connecting plate is 4 to 8 times the vertical distance from the motor shaft centerline to the crankshaft centerline, and the length of the connecting strip is the same as that of the connecting plate. The connecting plate is longer, so that the force of the connecting strip is evenly distributed to the connecting plate. At the same time, the longer and symmetrically arranged connecting plate can keep the inner end of the fan shaft stable when rotating at high speed, thereby improving the operating stability.

[0014] In the above oil-free air compressor, the connecting plate has a long strip-shaped notch arranged along the length direction, and the notch faces the crankshaft, and the end of the crankshaft is vertically inserted into the notch. This structure eliminates the connecting strip on the crankshaft, and directly inserts the end of the crankshaft into the notch of the connecting plate, which can also achieve the purpose of driving the connecting plate to rotate and simplify the overall structure.

[0015] In the above oil-free air compressor, the connecting member includes a rigid connecting strip fixedly connected to the end of the crankshaft, and the connecting strip is arranged along the vertical connection direction of the motor shaft and the crankshaft, and a sliding groove is radially opened on the end surface of the fan shaft, and the connecting strip is slidably connected in the sliding groove. The connecting strip of this structure is fixed relative to the crankshaft and slides relative to the fan shaft, and can also drive the fan shaft to rotate, but will not generate radial push and pull forces on the fan shaft.

[0016] In the above oil-free air compressor, the connecting member includes a long strip-shaped connecting plate, and notches are provided on the opposite two sides of the connecting plate along the length direction. The ends of the crankshaft and the ends of the fan shaft are provided with sliders, and the two sliders are respectively slidably connected in the notches on both sides of the connecting plate, and both ends of the bottom surface of the notch are provided with protruding limit parts. The connecting plate can slide relative to the crankshaft and the fan shaft at the same time to eliminate the radial push and pull force on the fan shaft, and the limit part limits the sliding distance of the connecting plate to prevent it from detaching or interfering with the inner wall of the crankcase.

[0017] Compared with the existing technology, this oil-free air compressor has the following advantages:

[0018] 1. Since the connecting parts can slide and adjust relative to the crankshaft or the fan shaft during operation to eliminate the radial push and pull force on the fan shaft, excessive wear of bearings, seals and other components between the fan shaft and the crankcase during long-term use, as well as unstable phenomena such as shaking of the fan shaft, are avoided, the fan shaft can operate stably and its service life can be increased.

[0019] 2. Due to the sliding design of the connecting parts, the coaxiality requirements between the motor shaft and the fan blade shaft and the accuracy of the connecting parts between the crankshaft and the fan blade shaft are relatively low during assembly, making assembly more convenient and reducing production costs.

[0020] 3. Since the connecting plate is long and symmetrically arranged, the force of the connecting strip is evenly distributed to the connecting plate. At the same time, the longer connecting plate can keep the inner end of the fan blade shaft stable when rotating at high speed, thereby improving the operating stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the structural explosion diagram of the oil-free air compressor.

[0022] Figure 2 It is a partial structural cross-sectional view of an oil-free air compressor.

[0023] Figure 3 yes Figure 1 A magnified view of the structure at center.

[0024] Figure 4 It is a structural schematic diagram of the connecting plate and the connecting strip.

[0025] Figure 5 It is a structural side view of the connecting plate and the connecting strip.

[0026] Figure 6 yes Figure 5 Structural cross-section view at BB in the middle.

[0027] Figure 7 yes Figure 5 Structural cross-section view at CC in the middle.

[0028] Figure 8 It is a partial structural sectional view of the oil-free air compressor in the second embodiment.

[0029] Fig. 9 It is a partial structural sectional view of the oil-free air compressor in Example 3.

[0030] Fig.10 It is a partial structural sectional view of the oil-free air compressor in the fourth embodiment.

[0031] Fig.11 It is a partial structural sectional view of the oil-free air compressor in the fifth embodiment.

[0032] In the figure, 1, motor; 11, motor shaft; 2, crankcase; 21, case body; 22, case cover; 3, fan blade; 31, fan blade shaft; 32, bearing; 33, seal; 34, slide groove; 4, crankshaft; 5, connecting plate; 51, bottom plate; 52, limit plate body; 53, elastic plate body; 54, recess; 55, counterweight hole; 56, limit part; 6, connecting strip; 61, connecting hole; 62, through hole; 63, abutting convex edge; 64, flaring; 65, screw; 7, slider; 8, cylinder body. DETAILED DESCRIPTION

[0033] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0034] Embodiment 1:

[0035] like Figure 1 As shown, an oil-free air compressor includes a motor 1, a crankcase 2 and a fan 3. The crankcase 2 includes a box body 21 and a box cover 22. The motor 1 is fixedly connected to one end of the box body 21, and the box cover 22 is fixed to the other end of the box body 21. The fan 3 is fixed with a fan shaft 31. The fan shaft 31 passes through the box cover 22 and extends into the box body 21. The fan shaft 31 is rotatably connected to the box cover 22 through a bearing 32. A sealing member 33 is also installed between the fan shaft 31 and the box cover 22. Two cylinder bodies 8 are fixed on the upper part of the outer wall of the box body 21. The two cylinder bodies 8 are arranged in a V shape. Figure 2 As shown, the motor shaft 11 of the motor 1 extends into the box body 21, and a crankshaft 4 is fixed at the end of the motor shaft 11, the crankshaft 4 is parallel to the motor shaft 11 and eccentrically arranged, and the motor shaft 11 is opposite to the fan blade shaft 31 and is arranged coaxially, and a long strip connecting plate 5 is connected between the fan blade shaft 31 and the crankshaft 4, the connecting plate 5 is vertically fixedly connected to the fan blade shaft 31, and the connecting plate 5 is arranged along the vertical connection direction of the motor shaft 11 and the crankshaft 4, combined with Figure 3 , Figure 4 As shown, there is a long strip-shaped recess 54 on the side of the connecting plate 5, and the recess 54 is arranged along the length direction of the connecting plate 5, and the recess 54 faces the crankshaft 4. The end of the crankshaft 4 is vertically fixed with a rigid connecting strip 6. The length direction of the connecting strip 6 is consistent with the length direction of the connecting plate 5, and the connecting strip 6 is inserted in the recess 54. The connecting strip 6 can slide relative to the connecting plate 5 along the length direction. Therefore, the cooperation between the connecting strip 6 and the connecting plate 5 makes the fan blade shaft 31 and the motor shaft 11 circumferentially fixed.

[0036] Specifically, combined Figure 5 , Figure 6As shown, the connecting plate 5 includes a long strip bottom plate 51, and both edges of the bottom plate 51 are provided with a row of limit plates 52, and a notch 54 is formed between the two rows of limit plates 52. The edge of the bottom plate 51 is provided with an elastic plate 53 between two adjacent limit plates 52, and the two rows of elastic plates 53 are relatively close to each other and tilted and pressed against the opposite side surfaces of the connecting strip 6. The bottom plate 51, the limit plates 52 and the elastic plates 53 are an integrated structure, and the bottom plate 51 and the fan blade shaft 31 are an integrated structure, combined with Figure 7 As shown, a connecting hole 61 is provided on the side of the connecting strip 6, a through hole 62 is provided on the bottom surface of the connecting hole 61, a supporting convex edge 63 is provided on the bottom surface of the connecting hole 61 around the opening of one end of the through hole 62, and a conical expansion 64 is provided in the circumference of the opening of the other end of the through hole 62, and the conical surface of the expansion 64 is opposite to the supporting convex edge 63, the end of the crankshaft 4 is inserted into the connecting hole 61 and fixedly connected by screws 65 penetrating the through hole 62, and the supporting convex edge 63 is pressed against the end surface of the crankshaft 4 under the action of the screws 65. The length of the connecting plate 5 is 6.5 times the vertical distance from the axis center line of the motor shaft 11 to the axis center line of the crankshaft 4, the length of the connecting strip 6 is the same as that of the connecting plate 5, the connecting plate 5 is symmetrically arranged relative to the axis center line of the fan blade shaft 31, and a plurality of symmetrically arranged counterweight holes 55 are provided on the opposite side surfaces of the bottom plate 51.

[0037] Embodiment 2:

[0038] The structure of the oil-free air compressor is basically the same as that of the first embodiment. Figure 8 As shown, the connecting plate 5 has a long strip-shaped recess 54 arranged along the length direction, and the recess 54 faces the crankshaft 4, and the end of the crankshaft 4 is vertically inserted into the recess 54. This structure eliminates the connecting strip 6 on the crankshaft 4, and directly inserts the end of the crankshaft 4 into the recess 54 of the connecting plate 5, which can also achieve the purpose of driving the connecting plate 5 to rotate and simplify the overall structure.

[0039] Embodiment three:

[0040] The structure of the oil-free air compressor is basically the same as that of the first embodiment. Fig. 9 As shown, the connecting member includes a rigid connecting strip 6 fixedly connected to the end of the crankshaft 4, and the connecting strip 6 is arranged along the vertical connection direction of the motor shaft 11 and the crankshaft 4. A sliding groove 34 is radially opened on the end surface of the fan blade shaft 31, and the connecting strip 6 is slidably connected in the sliding groove 34.

[0041] Embodiment 4:

[0042] The structure of the oil-free air compressor is basically the same as that of the first embodiment. Fig.10As shown, the connecting plate 5 is vertically fixed to the crankshaft 4, and the connecting plate 5 is arranged along the vertical connection direction of the motor shaft 11 and the crankshaft 4. The connecting plate 5 has a long strip-shaped recess 54 arranged along the length direction, and the recess 54 faces the fan blade shaft 31. The end of the fan blade shaft 31 has a slider 7, and the slider 7 is slidably connected in the recess 54, and the side of the slider 7 is slidably matched with the inner wall of the recess 54.

[0043] Embodiment five:

[0044] The structure of the oil-free air compressor is basically the same as that of the first embodiment. Fig.11 As shown, notches 54 are provided on the opposite side surfaces of the connecting plate 5 along the length direction, and the ends of the crankshaft 4 and the ends of the fan shaft 31 are provided with sliders 7, and the two sliders 7 are respectively slidably connected in the notches 54 on both sides of the connecting plate 5, and both ends of the bottom surface of the notch 54 are provided with protruding limit portions 56.

[0045] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0046] Although the terms such as motor 1, motor shaft 11, crankcase 2 are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. An oil-free air compressor, comprising a motor (1), a crankcase (2) fixed to the motor (1), and a fan (3) rotatably connected to the crankcase (2) via a fan shaft (31), wherein a motor shaft (11) of the motor (1) extends into the crankcase (2), and a parallel and eccentrically arranged crankshaft (4) is fixedly connected to the end of the motor shaft (11), the fan shaft (31) and the motor shaft (11) have the same axis, and a connecting member is connected between the fan shaft (31) and the crankshaft (4) to fix the motor shaft (11) and the fan shaft (31) in a circumferential direction, characterized in that: The connecting member is circumferentially fixed to the fan blade shaft (31), and in the direction of the vertical connection line between the motor shaft (11) and the crankshaft (4), the connecting member is slidably matched with at least one of the fan blade shaft (31) and the crankshaft (4); the connecting member comprises a long strip-shaped connecting plate (5), the connecting plate (5) is vertically fixedly connected to the fan blade shaft (31), the connecting plate (5) has a long strip-shaped notch (54) arranged along the length direction, and the notch (54) faces the crankshaft (4), and a rigid connecting strip (6) is vertically fixedly connected to the end of the crankshaft (4), the length direction of the connecting strip (6) is consistent with the length direction of the connecting plate (5), and the connecting strip (6) is inserted into the notch (5 4), the connecting plate (5) comprises a long strip-shaped bottom plate (51), both edges of the bottom plate (51) are provided with a row of limit plates (52), the above-mentioned notch (54) is formed between the two rows of limit plates (52), the edge of the bottom plate (51) is provided with elastic plates (53) between two adjacent limit plates (52), the two rows of elastic plates (53) are relatively close to each other and inclined and pressed against the opposite side surfaces of the connecting strip (6); a plurality of symmetrically arranged counterweight holes (55) are provided on the opposite side surfaces of the bottom plate (51); the length of the connecting plate (5) is 4 to 8 times the vertical distance from the axis center line of the motor shaft (11) to the axis center line of the crankshaft (4).

2. The oil-free air compressor according to claim 1, characterized in that: The connecting plate (5) and the fan blade shaft (31) are of an integrated structure. A connecting hole (61) is provided on the side surface of the connecting strip (6). A through hole (62) is provided on the bottom surface of the connecting hole (61). A supporting convex edge (63) is provided on the bottom surface of the connecting hole (61) around the opening of one end of the through hole (62). The opening of the other end of the through hole (62) has a conical expansion opening (64) in the circumferential direction. The conical surface of the expansion opening (64) is opposite to the supporting convex edge (63). The end of the crankshaft (4) is inserted into the connecting hole (61) and is fixedly connected to the through hole (62) by means of a screw (65). Under the action of the screw (65), the supporting convex edge (63) is pressed against the end surface of the crankshaft (4).

3. The oil-free air compressor according to claim 1, characterized in that: The connecting plate (5) is arranged symmetrically with respect to the axis of the fan blade shaft (31).

4. The oil-free air compressor according to claim 1, characterized in that: The connecting strip (6) has the same length as the connecting plate (5).

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