Oil-free air compressor transmission structure, oil-free air compressor and automobile

Abstract

The present invention relates to the technical field of vehicle air compressors, and in particular to an oil-free air compressor transmission structure and a vehicle. The oil-free air compressor transmission structure includes a motor housing, a motor assembly and a bearing assembly. The motor assembly is arranged inside the motor housing. The motor assembly includes an inner shaft, and the inner shaft is rotatably connected to the motor housing through the bearing assembly; it also includes a housing, a power assembly, and a large bearing. The housing is detachably connected to the motor housing. The power assembly includes a first half crank and a second half crank. The first half crank and the second half crank are mutually buckled and connected to form a crankshaft. The crankshaft is rotatably connected to the housing through the large bearing; it also includes a connecting piece. The first section and the inner shaft can be separated from each other, or can be detachably connected only through the connecting piece. In the present invention, the first section and the inner shaft can be detachably connected only through the connecting piece. The present invention solves the technical problem of how to remove the elastic coupling between the crankshaft and the inner shaft and connect them.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle air compressors, and in particular to an oil-free air compressor transmission structure, an oil-free air compressor and a vehicle. Background Art

[0002] Air compressor is the core equipment of vehicle pneumatic system. It is a device that converts the mechanical energy of the original motive force into gas pressure energy and is a device that generates air pressure for compressed air. Air compressors are widely used in the mechanical field and various production, decoration and manufacturing fields. They are the source of power for driving pneumatic tools.

[0003] Patent document CN201711132468.6 discloses an air compressor mentioned in the prior art, which includes an intercooler group, a high-pressure piston assembly, a low-pressure piston assembly, a piston cylinder, a crankcase and a crankshaft. The air compressor is powered by an electric motor, and the air compressor crankshaft is directly driven to rotate through an elastic coupling, and the high-pressure piston assembly and the low-pressure piston assembly placed on the crank make up and down reciprocating motions.

[0004] In the prior art, the crankshaft is connected to the inner shaft of the motor through an elastic coupling, but the elastic coupling is expensive and does not meet the current requirements for continuous cost reduction of air compressors. If the connection method between the crankshaft and the inner shaft can be changed so that the elastic coupling is removed from the connection structure between the crankshaft and the inner shaft, the cost of the elastic coupling can be reduced in the processing cost of the air compressor, thereby meeting the current cost reduction requirements of the air compressor.

[0005] At the same time, in the long-term use of existing technology motors, the vulnerable parts are mainly internal bearings. Due to the limited installation space inside the motor, the bearing load is small, and the harsh working conditions such as large vibration of the air compressor and frequent start-stop impact lead to poor life.

[0006] Therefore, the technical problem existing in the prior art is how to connect the crankshaft and the inner shaft by removing the elastic coupling.

[0007] Furthermore, it can also improve the life of the motor. Summary of the invention

[0008] In view of the technical problem in the prior art of how to connect the crankshaft and the inner shaft by removing the elastic coupling, the present invention provides an oil-free air compressor transmission structure, an oil-free air compressor and a car.

[0009] The present invention is achieved through the following technical solutions:

[0010] The oil-free air compressor transmission structure includes a motor housing, a motor assembly and a bearing assembly. The motor assembly is arranged inside the motor housing. The motor assembly includes an inner shaft and a rotor fixedly sleeved on the outer surface of the inner shaft. The inner shaft is rotatably connected to the motor housing through the bearing assembly.

[0011] It also includes a housing, a power assembly, and a large bearing. The housing is detachably connected to the motor housing. The power assembly includes a first half crank and a second half crank. The first half crank and the second half crank are mutually buckled and connected to form a crankshaft. The crankshaft is rotatably connected to the housing through the large bearing. The second half crank is located between the first half crank and the inner shaft along the axial direction of the inner shaft.

[0012] The invention is characterized in that the large bearing is sleeved on the crankshaft, and the large bearing is used to bear a part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and radial force of the inner shaft and the rotor of the motor assembly;

[0013] Along the axial direction of the inner shaft, a section of the second half crank away from the first half crank is the first section, and the first section is coaxially arranged with the inner shaft; further comprising a connecting member, the first section and the inner shaft can be separated from each other, or only detachably connected by the connecting member; wherein the connecting member is a bolt or a screw;

[0014] The bearing assembly includes a front bearing and a rear bearing, wherein the inner shaft is supported by the motor housing through the front bearing and the rear bearing, and the bearing outer ring of the front bearing and the bearing outer ring of the rear bearing are respectively clearance-matched with the motor housing, and along the axial direction of the inner shaft, the front bearing is located between the large bearing and the rear bearing; and the size and support strength of the large bearing are higher than those of the front bearing and the rear bearing;

[0015] or,

[0016] The bearing assembly only includes a rear bearing, wherein a section of the inner shaft away from the first half crank is the rear section, the rear section of the inner shaft is supported by the motor housing through the rear bearing, and the outer ring of the rear bearing is clearance-fitted with the motor housing; and the size and support strength of the large bearing are higher than those of the rear bearing.

[0017] Furthermore, the inner shaft is provided with a matching channel and a connecting channel which are coaxial and communicated with each other, the matching channel forms a first opening on one end face of the inner shaft, the first opening is arranged toward the first half crank, the connecting channel forms a second opening on the other end face of the inner shaft, the second opening is arranged away from the first half crank, a threaded blind hole is axially provided in the first section, and the opening of the threaded blind hole is located on one end face of the first section away from the first half crank;

[0018] The connecting piece has a head and a rod, the outer surface of the rod has threads, and the maximum cross-sectional diameter of the rod is smaller than the cross-sectional diameter of the head, and is also smaller than the cross-sectional diameter of the matching channel and the cross-sectional diameter of the connecting channel;

[0019] When the first section and the inner shaft are detachably connected through the connecting piece, the first section is inserted into the matching channel from the first opening, and the threaded blind hole, the matching channel and the connecting channel are coaxial; the connecting piece passes through the second opening, and a part of the rod of the connecting piece is threadedly connected to the threaded blind hole, and the head of the connecting piece is confined in the connecting channel.

[0020] Furthermore, a limited step surface is provided in the connecting channel, and when the first section and the inner shaft are detachably connected via the connecting piece, the head of the connecting piece is immovably limited between the limited step surface and the second opening;

[0021] It also includes an elastic gasket. When the first section and the inner shaft are detachably connected through a connecting piece, the elastic gasket is located between the limiting step surface and the head of the connecting piece along the axial direction of the connecting channel; one end face of the elastic gasket forms a surface-to-surface contact with the limiting step surface, and the other end face forms a surface-to-surface contact with the end face of the head of the connecting piece; the head of the connecting piece abuts against the limiting step surface through the elastic gasket.

[0022] Further, the outer surface of the first section is configured as a tapered outer surface, and the tapered outer surface of the first section is convergent in the direction from the first half crank to the inner shaft;

[0023] The inner surface of the matching channel is a conical inner surface; from the first half crank pointing to the inner shaft, the conical inner surface of the matching channel is convergent;

[0024] The taper angle of the tapered outer surface of the first section is consistent with the taper angle of the tapered inner surface of the matching channel.

[0025] Furthermore, the connecting channel includes a coaxially arranged threaded channel and a smooth channel, wherein the threaded channel is located between the matching channel and the smooth channel, the inner wall of the threaded channel has an internal thread for matching with the external thread of the bolt member, and the median diameter of the cross section of the threaded channel is larger than the diameter of the cross section of the threaded blind hole and smaller than the diameter of the cross section of the smooth channel.

[0026] Furthermore, a rear axle hole is provided at one end of the motor housing away from the first half crank; along the axial direction of the rear axle hole, the rear section of the inner shaft is passed through the rear axle hole and connected to the rear axle hole through a rear bearing, wherein the rear section of the inner shaft is connected to the inner ring of the rear bearing by interference fit;

[0027] A first step surface is arranged on the hole wall of the rear axle hole, and the first step surface extends along the radial direction of the rear axle hole. Along the axial direction of the rear bearing, there is a clearance fit between the bearing outer ring of the rear bearing and the first step surface.

[0028] Furthermore, along the radial direction of the rear bearing, there is a clearance fit between the circumferential outer surface of the bearing outer ring of the rear bearing and the circumferential inner wall of the rear axle hole.

[0029] Furthermore, along the axial direction of the rear bearing, a first elastic body is filled in the gap between the bearing outer ring of the rear bearing and the first step surface;

[0030] and / or,

[0031] Along the radial direction of the rear bearing, a second elastic body is filled in the gap between the circumferential outer surface of the bearing outer ring of the rear bearing and the circumferential inner wall of the rear shaft hole.

[0032] An oil-free air compressor comprises the above-mentioned oil-free air compressor transmission structure.

[0033] Automobile, comprising the above-mentioned oil-free air compressor.

[0034] Compared with the prior art, the advantages of the present invention are:

[0035] 1. In the present invention, the first section and the inner shaft can form a detachable connection only through a connecting piece, the first section is a part of the second half crank, and the second half crank is a part of the crankshaft; that is, in the present invention, the crankshaft and the inner shaft can form a detachable connection only through a connecting piece; therefore, the present invention achieves the removal of the coupling so that the crankshaft and the inner shaft are directly connected only through the connecting piece; in summary, the present invention solves the technical problem of how to remove the elastic coupling and connect the crankshaft and the inner shaft.

[0036] 2. In the prior art, the motor and the crankcase are independent parts, and the inner shaft of the motor is connected to the crankshaft of the crankcase through an elastic coupling. Due to the gap between the active end and the driven end of the elastic coupling, the load of the "inner shaft and rotor" in the prior art cannot be supported by the double-row angular contact ball bearing in the prior art. Generally speaking, two bearings are arranged inside the motor housing, and the two bearings are defined as the first bearing and the second bearing respectively, wherein when the motor is connected to the crankcase, the first bearing is located between the double-row angular contact ball bearing in the crankcase and the second bearing in the motor housing. The inner ring of the first bearing and the inner ring of the second bearing are respectively interference fit with the inner shaft, and the outer ring of the first bearing and the outer ring of the second bearing are respectively interference fit with the motor housing, so that the inner shaft cannot be displaced along the axial direction relative to the motor housing, and the motor housing supports the inner shaft and the rotor through the first bearing and the second bearing. During the operation of the motor, the load borne by the first bearing is greater than the load borne by the second bearing, resulting in the first bearing being worn before the second bearing. The wear of the first bearing reduces the life of the motor. In the present invention, the inner shaft of the motor is directly connected to the crankshaft of the crankcase through a connecting piece, so that the inner shaft of the motor and the crankshaft of the crankcase can be regarded as an integral structure, or in other words, the crankshaft of the crankcase can be regarded as an extended structure of the inner shaft of the motor; thus, the large bearing in the present invention can bear the load from the 'inner shaft and rotor' of the motor by 'directly connecting the inner shaft of the motor and the crankshaft of the crankcase through a connecting piece'; in the present invention, the inner shaft is equivalent to the inner shaft of the motor in the prior art; the position of the large bearing is equivalent to the position of the double-row angular contact ball bearing in the prior art, the position of the front bearing is equivalent to the position of the first bearing in the prior art, and the position of the rear bearing is equivalent to the position of the second bearing in the prior art; wherein, the size and support strength of the large bearing are much higher than the size and support strength of the front bearing and the rear bearing, and are also much higher than the size and support strength of the first bearing and the second bearing in the prior art.In the first scheme, the inner ring of the front bearing and the inner ring of the rear bearing in the motor are respectively interference fit with the inner shaft, but the outer ring of the front bearing and the outer ring of the rear bearing in the motor are respectively clearance fit with the housing, so that the inner shaft can be displaced relative to the housing during operation. The large bearing, the front bearing and the rear bearing in the present invention are jointly used to bear the load from the "inner shaft and rotor" of the motor; under this setting, the load from the "inner shaft and rotor" of the motor borne by the front bearing is less than the load from the "motor shaft and rotor" of its motor borne by the first bearing in the prior art; under the conditions that the running time of the motor is the same as the running time of the motor of the aforementioned prior art, and the working speed of the motor of the present invention is the same as the working speed of the motor of the prior art, the degree of wear suffered by the front bearing in the first scheme is lower than the degree of wear suffered by the first bearing in the prior art, so that the life of the front bearing is higher than the life of the first bearing in the prior art, and thus the life of the motor of the present invention is higher than the life of the motor of the prior art. In the second scheme, the inner ring of the rear bearing of the motor is interference fit with the inner shaft, but the outer ring of the rear bearing in the motor is clearance fit with the motor housing, so that the inner shaft can be displaced axially relative to the motor housing during operation; since the front bearing is cancelled, the large bearing and the rear bearing are used together to bear the load from the "inner shaft and rotor" of the motor; on this basis, since the size and support strength of the large bearing are greater than the size and support strength of the cancelled front bearing, when the running time of the motor is the same as the running time of the motor in the aforementioned "first scheme", and when the running speed of the motor is the same as the running speed of the aforementioned "first scheme", the wear degree of the large bearing in the second scheme is lower than the wear degree of the front bearing in the aforementioned "first scheme", so that the life of the large bearing is longer than the life of the front bearing in the first scheme; since the life of the front bearing in the aforementioned "first scheme" is longer than the life of the first bearing in the prior art, and the life of the large bearing is longer than the life of the front bearing in the first scheme, the life of the large bearing in the second scheme is longer than the life of the first bearing in the prior art, and thus the life of the motor in the second scheme is longer than the life of the motor in the prior art.

[0037] 3. In the present invention, the rear section of the inner shaft is connected with the inner ring of the rear bearing by interference fit, that is, the rear section of the inner shaft and the inner ring of the rear bearing rotate synchronously; the outer ring of the rear bearing and the first step surface are clearance fit, that is, there is a gap between the outer ring of the rear bearing and the first step surface; then, due to the setting of the gap between the outer ring of the rear bearing and the first step surface, the position of the inner shaft along the axial direction of the inner shaft is adjustable; the same is true for the setting of the front bearing; thereby achieving the purpose of making the axial position of the inner shaft adjustable.

[0038] 4. In the present invention, the outer surface of the outer ring of the rear bearing is clearance-matched with the inner wall of the rear shaft hole. This means that when the inner shaft and the first section are not coaxial, the inner shaft can be adjusted in radial direction so that the axis of the inner shaft and the axis of the first section are in the same straight line, and then the inner shaft and the first section are assembled together. Therefore, the present invention also achieves the purpose of making the inner shaft adjustable in radial direction.

[0039] 5. In the prior art, an elastic coupling is used to connect the inner shaft of the motor with the crank shaft. Since the elastomer of the elastic coupling is generally a plastic product such as polyurethane, it has a short life and is subject to the risk of failure due to aging, wear, cracking, etc. after long-term use. In the present invention, since the use of an elastic coupling is avoided and a metal connector is used to connect the inner shaft of the motor with the crank shaft, the above-mentioned problem can also be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic cross-sectional view of the transmission structure of the oil-free air compressor in Example 1;

[0041] Figure 2 for Figure 1 Schematic diagram of the middle limit step surface;

[0042] Figure 3 for Figure 1 A magnified schematic diagram of the middle A area;

[0043] Figure 4 for Figure 1 A magnified schematic diagram of the middle B area;

[0044] Figure 5 for Figure 1 Enlarged schematic diagram of the middle C area;

[0045] Figure 6 This is a cross-sectional schematic diagram of the transmission structure of the oil-free air compressor of Example 2.

[0046] Markings in the figure: motor housing (1), inner shaft (2), housing (3), first half crank (4), second half crank (5), large bearing (6), first section (7), matching channel (8), connecting channel (9), first opening (10), second opening (11), threaded blind hole (12), connecting piece (13), head (14), rod (15), limiting step surface (16), elastic washer (17), threaded channel (18), smooth channel (19), bolt member (20), rear section (21), rear shaft hole (22), rear bearing (23), first step surface (24), first elastic body (25), second elastic body (26), front bearing (27), front shaft hole (28), rotor (29), stator (30), counterweight (31), low-pressure piston connecting rod assembly (32), low-pressure bearing (33), high-pressure piston connecting rod assembly (34), high-pressure bearing (35), front section (36), second step surface (37). DETAILED DESCRIPTION

[0047] The following is a further non-restrictive detailed description of the technical solution of the invention in conjunction with the preferred embodiments and the accompanying drawings. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and cannot be understood as limitations on the present invention. Example 1

[0048] like Figure 1As shown, this embodiment proposes an oil-free air compressor transmission structure, which includes a motor housing 1, a motor assembly and a bearing assembly. The motor assembly is arranged inside the motor housing 1. The motor assembly includes an inner shaft 2 and a rotor 29 fixedly sleeved on the outer surface of the inner shaft 2. The inner shaft 2 is rotatably connected to the motor housing 1 through the bearing assembly; it also includes a box body 3, a power assembly, and a large bearing 6. The box body 3 is detachably connected to the motor housing 1. The power assembly includes a first half crank 4 and a second half crank 5. The first half crank 4 and the second half crank 5 are interlocked. The crankshaft is rotatably connected to the housing 3 via a large bearing 6; wherein, along the axial direction of the inner shaft 2, the second half crank 5 is located between the first half crank 4 and the inner shaft 2; it is characterized in that the large bearing 6 is sleeved on the crankshaft, and the large bearing 6 is used to bear part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and radial force of the inner shaft 2 and the rotor 29 of the motor assembly, such as gravity, start-stop impact force, magnetic field tension, random vibration of the vehicle, eccentric assembly force, etc.; along the axial direction of the inner shaft 2, the second half crank 5 is located between the first half crank 4 and the inner shaft 2. The section of the handle 5 away from the first half crank 4 is the first section 7, and the first section 7 is coaxially arranged with the inner shaft 2; it also includes a connecting piece 13, and the first section 7 and the inner shaft 2 can be separated from each other, or only connected detachably by the connecting piece 13; wherein the connecting piece 13 is a bolt or a screw; the bearing assembly includes a front bearing 27 and a rear bearing 23, wherein the inner shaft 2 is supported by the motor housing 1 through the front bearing 27 and the rear bearing 23, and the bearing outer ring of the front bearing 27 and the bearing outer ring of the rear bearing 23 are respectively matched with the motor housing 1 in a clearance manner, and along the inner shaft 2 Axially, the front bearing 27 is located between the large bearing 6 and the rear bearing 23; and the size and support strength of the large bearing 6 are higher than those of the front bearing 27 and the rear bearing 23; or, the bearing assembly only includes the rear bearing 23, wherein a section of the inner shaft 2 away from the first half crank 4 is the rear section 21, and the rear section 21 of the inner shaft 2 is supported by the motor housing 1 through the rear bearing 23, and the outer ring of the rear bearing 23 is clearance-fitted with the motor housing 1; and the size and support strength of the large bearing 6 are higher than those of the rear bearing 23.

[0049] The motor assembly includes an inner shaft 2, which is an axial structure extending in a straight line; the motor assembly also includes a rotor 29, which is sleeved on the outer surface of the inner shaft 2 and fixed to the inner shaft 2; the motor assembly also includes a stator 30, which is connected to the motor housing 1 and is arranged around the rotor 29; the motor assembly also includes a bearing assembly, and the inner shaft 2 is rotatably connected to the motor housing 1 through the bearing assembly. At the same time, the combination of the rotor 29 and the inner shaft 2 is supported by the motor housing 1 through the bearing assembly; when the stator 30 generates a rotating magnetic field, the rotor 29 drives the inner shaft 2 to rotate coaxially and synchronously.

[0050] The power assembly includes a first half crank 4 and a second half crank 5. The structures of the first half crank 4 and the second half crank 5 are similar but not the same. The first half crank 4 and the second half crank 5 are interlocked and connected to form a crank shaft. The connection method can refer to the content disclosed in patent document CN202220104964.0; the power assembly also includes a counterweight part 31, which is detachably connected to the first half crank 4 to balance the reciprocating inertia moment of the crank shaft rotation; the power assembly also includes a low-pressure piston connecting rod assembly 32, a low-pressure Bearing 33, the low-pressure piston connecting rod assembly 32 is rotatably connected to the second half crank 5 through the low-pressure bearing 33; the power assembly also includes a high-pressure piston connecting rod assembly 34 and a high-pressure bearing 35, and the high-pressure piston connecting rod assembly 34 is rotatably connected to the first half crank 4 through the high-pressure bearing 35; and the overall weight of the low-pressure piston connecting rod assembly 32, the low-pressure bearing 33, the high-pressure piston connecting rod assembly 34, the high-pressure bearing 35, the counterweight part 31, the first half crank 4 and the second half crank 5 are all supported by the box body 3 through the large bearing 6.

[0051] In summary, one section of the second half crank 5 is detachably connected to the first half crank 4 ; another section of the second half crank 5 , namely the first section 7 , extends out of the box body 3 and is detachably connected to the inner shaft 2 only through the connecting piece 13 .

[0052] like Figure 1 to Figure 3 As shown, the first section 7 and the inner shaft 2 are connected only by the connecting piece 13, specifically: the inner shaft 2 is provided with a matching channel 8 and a connecting channel 9 which are coaxial and communicated with each other, the matching channel 8 forms a first opening 10 at one end face of the inner shaft 2, the first opening 10 is arranged toward the first half crank 4, the connecting channel 9 forms a second opening 11 at the other end face of the inner shaft 2, the second opening 11 is arranged away from the first half crank 4, a threaded blind hole 12 is axially arranged in the first section 7, the opening of the threaded blind hole 12 is located at the end face of the first section 7 away from the first half crank 4; the connecting piece 13 has a head 14 and a rod 15, the outer surface of the rod 15 has a thread, the maximum cross-sectional diameter of the rod 15 is smaller than the cross-sectional diameter of the head 14, and is also smaller than the cross-sectional diameter of the matching channel 8 and the cross-sectional diameter of the connecting channel 9; when the first section 7 and the inner shaft 2 are detachably connected through the connecting piece 13, the first section 7 is inserted into the matching channel 8 from the first opening 10, and the threaded blind hole 12, the matching channel 8 and the connecting channel 9 are coaxial; the connecting piece 13 passes through the second opening 11, and a part of the rod 15 of the connecting piece 13 is threadedly connected to the threaded blind hole 12, and the head 14 of the connecting piece 13 is confined in the connecting channel 9.

[0053] In this embodiment, by providing the matching channel 8, the connecting channel 9 and the threaded blind hole 12 inside the inner shaft 2, the threaded blind hole 12, the matching channel 8 and the connecting channel 9 are coaxial during assembly, and the first section 7 is inserted into the matching channel 8. The connecting member 13 moves only in a space restricted and enclosed by the hole wall of the threaded blind hole 12, a portion of the inner wall of the matching channel 8 and the inner wall of the connecting channel 9, and the first section 7 is detachably connected to the inner shaft 2, that is, the first section 7 and the inner shaft 2 are detachably connected via the connecting member 13, and the connecting member 13 only occupies the internal space of the first section 7 and the inner shaft 2, thereby avoiding the connecting member 13 occupying the external space of the first section 7 and the inner shaft 2.

[0054] The first scheme is that the bearing assembly includes both the front bearing 27 and the rear bearing 23. In the first scheme, the combination of the 'inner shaft 2 and the rotor 29' is supported by the large bearing 6, the front bearing 27 and the rear bearing 23 at three points respectively; the second scheme is that the bearing assembly only includes the rear bearing 23. The second scheme is mainly suitable for small-displacement air compressor models. Since the rotor shaft span of small-displacement air compressors is short, the front bearing 27 can be eliminated, so that the combination of the power assembly and the motor assembly can meet the use requirements by only being supported at two points by the large bearing 6 and the rear bearing 23.

[0055] In the first and second schemes, the bearing assembly includes a rear bearing 23, and the outer ring of the rear bearing 23 is clearance-matched with the motor housing 1; in these two schemes, the specific structure of the clearance-matched outer ring of the rear bearing 23 and the motor housing 1 is as follows:

[0056] like Figure 1 , Figure 4 As shown, specifically, a rear shaft hole 22 is provided at one end of the motor housing 1 away from the first half crank 4; along the axial direction of the rear shaft hole 22, the rear section 21 of the inner shaft 2 is penetrated through the rear shaft hole 22 and connected to the rear shaft hole 22 through the rear bearing 23, wherein the rear section 21 of the inner shaft 2 is connected with the inner ring of the rear bearing 23 by interference fit; a first step surface 24 is provided on the hole wall of the rear shaft hole 22, and the first step surface 24 extends along the radial direction of the rear shaft hole 22, and along the axial direction of the rear bearing 23, there is a clearance fit between the outer ring of the rear bearing 23 and the first step surface 24. And, along the radial direction of the rear bearing 23, there is a clearance fit between the outer circumferential surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear shaft hole 22.

[0057] As can be seen from the foregoing, in the first solution, the outer ring of the front bearing 27 is clearance-matched with the motor housing 1; specifically:

[0058] like Figure 1 , Figure 5As shown, preferably, the bearing assembly also includes a front bearing 27, and along the axial direction of the inner shaft 2, a section of the inner shaft 2 facing the first half crank 4 is a front section 36; a front shaft hole 28 is provided at one end of the motor housing 1 facing the first half crank 4, and along the axial direction of the front shaft hole 28, the front section 36 of the inner shaft 2 is penetrated through the front shaft hole 28 and is connected to the front shaft hole 28 through the front bearing 27.

[0059] like Figure 1 , Figure 5 As shown, the front section 36 of the inner shaft 2 is connected with the inner ring of the front bearing 27 by interference fit, the hole wall of the front shaft hole 28 is provided with a second step surface 37, the second step surface 37 extends along the radial direction of the front shaft hole 28, and the outer ring of the front bearing 27 and the second step surface 37 are clearance fit. Also, the outer circumferential outer surface of the outer ring of the front bearing 27 and the circumferential inner wall of the front shaft hole 28 are clearance fit.

[0060] The front bearing 27 is arranged in a manner similar to the arrangement of 'the outer ring of the rear bearing 23 is clearance-matched with the motor housing 1', and the structures of the front bearing 27 and the rear bearing 23 are arranged in mirror symmetry.

[0061] As can be seen from the background technology, the technical problem existing in the prior art is how to connect the crankshaft and the inner shaft without the elastic coupling.

[0062] In this embodiment, the first section 7 and the inner shaft 2 can form a detachable connection only through the connecting piece 13, the first section 7 is a part of the second half crank 5, and the second half crank 5 is a part of the crankshaft; that is, in this embodiment, the crankshaft and the inner shaft 2 can form a detachable connection only through the connecting piece 13; therefore, this embodiment realizes the removal of the coupling, so that the crankshaft and the inner shaft 2 are directly connected only through the connecting piece 13; in summary, this embodiment solves the technical problem of how to remove the elastic coupling and connect the crankshaft and the inner shaft.

[0063] Furthermore, the connecting member 13 is a bolt or a screw, which is made of metal; its processing cost or purchase cost is much lower than that of the coupling; compared with the prior art, this embodiment also achieves the purpose of cost saving.

[0064] In the prior art, the motor and crankcase are independent components, and the inner shaft of the motor is connected to the crankshaft of the crankcase through an elastic coupling. Due to the gap between the active end and the driven end of the elastic coupling, the load of the "inner shaft and rotor" in the prior art cannot be supported by the double-row angular contact ball bearing in the prior art. Generally speaking, two bearings are arranged inside the motor housing, and the two bearings are defined as the first bearing and the second bearing respectively, wherein when the motor is connected to the crankcase, the first bearing is located between the double-row angular contact ball bearing in the crankcase and the second bearing in the motor housing. The inner ring of the first bearing and the inner ring of the second bearing are respectively interference fit with the inner shaft, and the outer ring of the first bearing and the outer ring of the second bearing are respectively interference fit with the motor housing, so that the inner shaft cannot be displaced along the axial direction relative to the motor housing, and the motor housing supports the inner shaft and the rotor through the first bearing and the second bearing. During the operation of the motor, the load borne by the first bearing is greater than the load borne by the second bearing, resulting in the first bearing being worn before the second bearing. The wear of the first bearing reduces the life of the motor.

[0065] In this embodiment, the inner shaft 2 of the motor is directly connected to the crankshaft of the crankcase through the connecting piece 13, so that the inner shaft 2 of the motor and the crankshaft of the crankcase can be regarded as an integral structure, or in other words, the crankshaft of the crankcase can be regarded as an extended structure of the inner shaft 2 of the motor; thus, in this embodiment, the large bearing 6 can bear the load from the inner shaft 2 and the rotor 29 of the motor by 'the inner shaft 2 of the motor and the crankshaft of the crankcase are directly connected through the connecting piece 13';

[0066] In this embodiment, the inner shaft 2 is equivalent to the inner shaft of the motor in the prior art; the position of the large bearing 6 is equivalent to the position of the double-row angular contact ball bearing in the prior art, the position of the front bearing 27 is equivalent to the position of the first bearing in the prior art, and the position of the rear bearing 23 is equivalent to the position of the second bearing in the prior art; wherein, the size and support strength of the large bearing 6 are much higher than the size and support strength of the front bearing 27 and the rear bearing 23, and are also much higher than the size and support strength of the first bearing and the second bearing in the prior art.

[0067] In the first scheme, the inner ring of the front bearing 27 and the inner ring of the rear bearing 23 in the motor are respectively interference fit with the inner shaft 2, but the outer ring of the front bearing 27 and the outer ring of the rear bearing 23 in the motor are respectively clearance fit with the housing, so that the inner shaft 2 can be displaced relative to the housing during operation. The large bearing 6, the front bearing 27 and the rear bearing 23 in this embodiment are used together to bear the load from the 'inner shaft 2 and the rotor 29' of the motor; under this setting, the load from the 'inner shaft 2 and the rotor 29' of the motor borne by the front bearing 27 is less than the load from the 'motor shaft and the rotor 29' of its motor borne by the first bearing in the prior art; under the condition that the running time of the motor is the same as the running time of the motor in the aforementioned prior art, and the working speed of the motor in this embodiment is the same as the working speed of the motor in the prior art, the wear degree of the front bearing 27 in the first scheme is lower than the wear degree of the first bearing in the prior art, so that the life of the front bearing 27 is higher than the life of the first bearing in the prior art, and thus the life of the motor in this embodiment is higher than the life of the motor in the prior art.

[0068] In the second scheme, the inner ring of the rear bearing 23 of the motor is interference fit with the inner shaft 2, but the outer ring of the rear bearing 23 in the motor is clearance fit with the motor housing 1, so that the inner shaft 2 can be displaced axially relative to the motor housing 1 during operation; since the front bearing 27 is eliminated, the large bearing 6 and the rear bearing 23 are used together to bear the load from the 'inner shaft 2 and rotor 29' of the motor; on this basis, since the size and support strength of the large bearing 6 are greater than the size and support strength of the eliminated front bearing 27, when the running time of the motor is the same as that of the motor in the aforementioned 'first scheme', When the running speed of the motor is the same as that of the aforementioned 'first solution', the degree of wear of the large bearing 6 in the second solution is lower than the degree of wear of the front bearing 27 in the aforementioned 'first solution', so that the life of the large bearing 6 is longer than the life of the front bearing 27 in the first solution; since the life of the front bearing 27 in the aforementioned 'first solution' is longer than the life of the first bearing in the prior art, and the life of the large bearing 6 is longer than the life of the front bearing 27 in the first solution, the life of the large bearing 6 in the second solution is longer than the life of the first bearing in the prior art, and thus the life of the motor in the second solution is longer than the life of the motor in the prior art.

[0069] Furthermore, in the present embodiment, in the first scheme, the inner shaft 2 is rotatably connected to the motor housing 1 through the front bearing 27 and the rear bearing 23 respectively; therefore, a small part of the motor core load that the bearing assembly needs to bear is shared by the front bearing 27 and the rear bearing 23, thereby further reducing the loads borne by the front bearing 27 and the rear bearing 23 respectively, which is more conducive to improving the service life of the front bearing 27 and the rear bearing 23.

[0070] Furthermore, in the prior art, an elastic coupling is used to connect the inner shaft of the motor with the crank shaft. However, since the elastomer of the elastic coupling is generally a plastic product such as polyurethane, it has a short lifespan and is subject to the risk of failure due to aging, wear, and cracking due to long-term use. In this embodiment, since the use of an elastic coupling is avoided and a metal connector 13 is used to connect the inner shaft of the motor with the crank shaft, the above-mentioned problem can also be avoided.

[0071] Furthermore, when the transmission structure of the oil-free air compressor is assembled, it is usually as follows: the motor assembly and the bearing assembly are respectively assembled into the motor housing 1, the power assembly and the large bearing 6 are respectively assembled into the housing 3, and then the motor housing 1 and the housing 3 are snapped together so that the first section 7 and the inner shaft 2 are coaxially connected; however, in actual assembly, after the motor housing 1 and the housing 3 are snapped together, along the axial direction of the inner shaft 2, the assembly position between the inner shaft 2 and the first section 7 often does not match, resulting in a gap between the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8, that is, the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8 cannot be tightly attached.

[0072] In this embodiment, the rear section 21 of the inner shaft 2 is connected with the inner ring of the rear bearing 23 by interference fit, that is, the rear section 21 of the inner shaft 2 and the inner ring of the rear bearing 23 rotate synchronously; the outer ring of the rear bearing 23 and the first step surface 24 are clearance fit, that is, there is a gap between the outer ring of the rear bearing 23 and the first step surface 24; therefore, due to the setting of the gap between the outer ring of the rear bearing 23 and the first step surface 24, the position of the inner shaft 2 along the axial direction of the inner shaft 2 is adjustable. For example, Figure 4 As shown, when the inner shaft 2 is required to Figure 4 When the inner shaft 2 moves to the right, the inner ring of the rear bearing 23 drives the inner ring of the rear bearing 23 to move to the right, and the inner ring of the rear bearing 23 is connected to the outer ring of the rear bearing 23, which causes the outer ring of the rear bearing 23 to move to the right as well; thereby achieving the purpose of making the axial position of the inner shaft 2 adjustable.

[0073] Furthermore, after the motor housing 1 and the box body 3 are fastened together, it is often easy for the inner shaft 2 to be out of coaxiality with the first section 7 along the radial direction of the inner shaft 2 .

[0074] In this embodiment, the outer surface of the outer ring of the rear bearing 23 is clearance-matched with the inner wall of the circumference of the rear shaft hole 22. As a result, when the inner shaft 2 and the first section 7 are not coaxial, the inner shaft 2 can be adjusted in the radial direction so that the axis of the inner shaft 2 and the axis of the first section 7 are in the same straight line, and then the inner shaft 2 and the first section 7 are assembled together. Therefore, in this embodiment, the purpose of making the inner shaft 2 adjustable in radial position is also achieved.

[0075] It is mentioned in the foregoing that the head 14 of the connecting member 13 is confined in the connecting channel 9; specifically, in this embodiment, a limiting step surface 16 is provided in the connecting channel 9, and when the first section 7 and the inner shaft 2 are detachably connected through the connecting member 13, the head 14 of the connecting member 13 is immovably confined between the limiting step surface 16 and the second opening 11.

[0076] Usually, the limit step surface 16 is limited by processing conditions and is difficult to be processed into a plane, while the head 14 of the connector 13, the end surface on one side facing the limit step surface 16, is usually a plane, which easily leads to the contact between the head 14 of the connector 13 and the limit step surface 16, usually point-to-point contact or line-to-line contact, which results in the contact area between the head 14 of the connector 13 and the limit step surface 16 being too small, and the friction between the head 14 of the connector 13 and the limit step surface 16 being too small. During the process of motor starting and inner shaft 2 rotating, the head 14 and the limit step surface 16 slip relatively, making it impossible for the inner shaft 2 and the second half crank 5 to rotate synchronously; therefore, how to increase the friction between the head 14 of the connector 13 and the limit step surface 16 is a technical problem that needs to be solved, and this technical problem is solved by the following technical solution.

[0077] like Figure 1 to Figure 3 As shown, the oil-free air compressor transmission structure of this embodiment also includes an elastic washer 17. When the first section 7 and the inner shaft 2 are detachably connected through the connecting piece 13, the elastic washer 17 is located between the limiting step surface 16 and the head 14 of the connecting piece 13 along the axial direction of the connecting channel 9; one side end face of the elastic washer 17 forms a surface-to-surface contact with the limiting step surface 16, and the other side forms a surface-to-surface contact with the end face of the head 14 of the connecting piece 13; the head 14 of the connecting piece 13 abuts against the limiting step surface 16 through the elastic washer 17.

[0078] The elastic gasket 17 is elastic, and its material can be any known material in the prior art, such as rubber material, which is not limited here.

[0079] In the present embodiment, one side end surface of the elastic gasket 17 facing the limiting step surface 16 is configured to be in the same shape as the limiting step surface 16, such as a curved surface, so that the one side end surface of the elastic gasket 17 facing the limiting step surface 16 forms a surface-to-surface contact with the limiting step surface 16; and one side end surface of the elastic gasket 17 facing the head 14 of the connector 13 is configured to be a plane consistent with the end surface of the head 14, so that the one side end surface of the elastic gasket 17 facing the head 14 of the connector 13 forms a surface-to-surface contact with the head 14 of the connector 13.

[0080] In this embodiment, an elastic washer 17 is arranged between the head 14 of the connecting member 13 and the limiting step surface 16, and the head 14 and the limiting step surface 16 of the connecting member 13 form surface-to-surface contact with the elastic washer 17 respectively, which results in that during the rotation of the inner shaft 2, the inner shaft 2 drives the elastic washer 17 to rotate synchronously through the friction between the limiting step surface 16 and the elastic washer 17, and then the friction between the elastic washer 17 and the head 14 of the connecting member 13 drives the connecting member 13 to rotate synchronously with the inner shaft 2, and then the threaded connection relationship between the connecting member 13 and the threaded blind hole 12 in the first section 7 of the second half crank 5 drives the crank shaft to rotate synchronously with the inner shaft 2.

[0081] In the present embodiment, an elastic washer 17 is provided between the head 14 of the connector 13 and the limiting step surface 16. The elastic washer 17 forms surface-to-surface contact with the head 14 of the connector 13 and the limiting step surface 16 respectively, thereby increasing the friction between the head 14 of the connector 13 and the limiting step surface 16 through the elastic washer 17. Therefore, the present embodiment solves the technical problem of how to increase the friction between the head 14 of the connector 13 and the limiting step surface 16.

[0082] like Figure 1 As shown, further, the present embodiment also includes the following technical solutions: the oil-free air compressor transmission structure of the present embodiment, the outer surface of the first section 7 is configured as a conical outer surface, and the conical outer surface of the first section 7 is convergent in the direction from the first half crank 4 to the inner shaft 2; the inner surface of the matching channel 8 is a conical inner surface; the conical inner surface of the matching channel 8 is convergent in the direction from the first half crank 4 to the inner shaft 2; wherein, the taper angle of the conical outer surface of the first section 7 is consistent with the taper angle of the conical inner surface of the matching channel 8.

[0083] The purpose of this setting is mainly two-fold:

[0084] Firstly, in the connection process between the second half crank 5 and the inner shaft 2, the first section 7 needs to be gradually inserted into the matching channel 8. During the process of gradually inserting the first section 7 into the matching channel 8, the first section 7 moves along the direction of the first half crank 4 pointing to the inner shaft 2. Along the direction of the first half crank 4 pointing to the inner shaft 2, the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8 are both convergent. As a result, the conical inner surface of the matching channel 8 guides the conical outer surface of the first section 7, so that during the blind insertion of the first section 7, it is convenient to align the first section 7 coaxially with the inner shaft 2.

[0085] Secondly, after the first section 7 of the second half crank 5 is inserted into the matching channel 8 of the inner shaft 2, the threaded engagement relationship between the rod portion of the connecting piece 13 and the internal threaded blind hole 12 of the first section 7 makes the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8 close to each other, thereby increasing the contact area between the first section 7 and the matching channel 8 and increasing the friction between the first section 7 and the matching channel 8.

[0086] Furthermore, it is mentioned in the first and second schemes above that, along the axial direction of the rear bearing 23, there is a clearance fit between the outer ring of the rear bearing 23 and the first step surface 24; and, along the radial direction of the rear bearing 23, there is a clearance fit between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22; this results in that the friction between the outer ring of the rear bearing 23 and the hole wall of the rear axle hole 22 is too small, and the outer ring of the rear bearing 23 is very easy to idle. Once the outer ring of the rear bearing 23 idles, the outer ring of the rear bearing 23 will slide against the rear axle hole 22, causing the surface of the outer ring of the rear bearing 23 to be worn; therefore, how to increase the friction between the outer ring of the rear bearing 23 and the hole wall of the rear axle hole 22 is a technical problem that needs to be solved, and this technical problem is solved by the following technical scheme.

[0087] Along the axial direction of the rear bearing 23, the gap between the outer ring of the rear bearing 23 and the first step surface 24 is filled with a first elastomer 25; and / or, along the radial direction of the rear bearing 23, the gap between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22 is filled with a second elastomer 26.

[0088] The first elastomer 25 can be a rubber washer, a metal corrugated washer or other structure, which can be squeezed and deformed along the axial direction of the rear bearing 23; in this embodiment, along the axial direction of the rear bearing 23, the gap between the outer ring of the rear bearing 23 and the first step surface 24 is filled by the first elastomer 25, thereby increasing the friction between the side surface of the outer ring of the rear bearing 23 and the first step surface 24 through the first elastomer 25.

[0089] The second elastomer 26 can be an O-ring structure, which can be squeezed and deformed along the radial direction of the rear bearing 23. In this embodiment, the gap between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22 is filled with the second elastomer 26, thereby increasing the friction between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22 through the second elastomer 26.

[0090] To summarize, this embodiment increases the friction between the side surface of the outer ring of the rear bearing 23 and the first step surface 24 by filling the first elastomer 25 in the gap between the outer ring of the rear bearing 23 and the first step surface 24; and / or, fills the second elastomer 26 in the gap between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22, thereby increasing the friction between the circumferential outer surface of the outer ring of the rear bearing 23 and the circumferential inner wall of the rear axle hole 22; thereby avoiding the problem of the outer ring of the rear bearing 23 rotating relative to the rear axle hole 22.

[0091] In the first solution, correspondingly, along the axial direction of the front bearing 27, the gap between the outer ring of the front bearing 27 and the second step surface 37 is filled with a third elastic body; and / or, along the radial direction of the front bearing 27, the gap between the circumferential outer surface of the outer ring of the front bearing 27 and the circumferential inner wall of the front shaft hole 28 is filled with a fourth elastic body. The third elastic body has the same structure as the first elastic body 25, and the fourth elastic body has the same structure as the second elastic body 26. Example 2

[0092] Most of the structures of the transmission structure of the oil-free air compressor in this embodiment are the same as those in Embodiment 1, and the contents of this embodiment focus on the parts that are different from those in Embodiment 1.

[0093] In Embodiment 1, the first section 7 and the inner shaft 2 are detachably connected via a connecting piece 13 , and the tapered outer surface of the first section 7 is in tight contact with the tapered inner surface of the matching channel 8 of the inner shaft 2 .

[0094] When the air compressor needs to be disassembled, the connector 13 should be unscrewed and removed first, and then the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8 should be separated from each other; in order to facilitate the separation of the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8, the present embodiment also includes the following technical solutions:

[0095] like Figure 6As shown, the connecting channel 9 includes a coaxially arranged threaded channel 18 and a smooth channel 19, wherein the threaded channel 18 is located between the matching channel 8 and the smooth channel 19, the channel inner wall of the threaded channel 18 has an internal thread for matching with the external thread of the bolt member 20, and the middle diameter of the cross section of the threaded channel 18 (the middle diameter is the diameter of an imaginary cylinder at which the widths of the groove and the protrusion on the inner tooth profile of the thread axial cross section are equal) is larger than the diameter of the cross section of the threaded blind hole 12, and smaller than the diameter of the cross section of the smooth channel 19.

[0096] The outer surface of the bolt member 20 has threads. In the present embodiment, the bolt member 20 is a large-diameter bolt, and the thread median diameter thereof is larger than the thread median diameter of the rod portion 15 of the connecting member 13 in the first embodiment.

[0097] During disassembly, the connecting member 13 is unscrewed and removed, one end of the bolt member 20 passes through the threaded channel 18 and abuts against the end face of the first section 7, a portion of the outer surface of the bolt member 20 is threadedly matched with the inner thread of the threaded channel 18, and the bolt member 20 is screwed in along the direction of the smooth channel 19 pointing to the threaded channel 18, so that the bolt member 20 pushes the end face of one side of the first section 7 located in the matching channel 8, thereby separating the conical outer surface of the first section 7 and the conical inner surface of the matching channel 8 from each other. Example 3

[0098] This embodiment provides an oil-free air compressor, which includes the oil-free air compressor transmission structure mentioned in Embodiment 1. Example 4

[0099] This embodiment provides a car, which includes the oil-free air compressor mentioned in Embodiment 3.

[0100] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. An oil-free air compressor transmission structure, comprising a motor housing (1), a motor assembly and a bearing assembly, wherein the motor assembly is arranged inside the motor housing (1), the motor assembly comprises an inner shaft (2), and a rotor (29) fixedly sleeved on the outer surface of the inner shaft (2), and the inner shaft (2) is rotatably connected to the motor housing (1) through the bearing assembly; It also includes a housing (3), a power assembly, and a large bearing (6); the housing (3) is detachably connected to the motor housing (1); the power assembly includes a first half crank (4) and a second half crank (5); the first half crank (4) and the second half crank (5) are interlocked and connected to form a crankshaft; the crankshaft is rotatably connected to the housing (3) via the large bearing (6); wherein: Along the axial direction of the inner shaft (2), the second half crank (5) is located between the first half crank (4) and the inner shaft (2); The invention is characterized in that the large bearing (6) is sleeved on the crankshaft, and the large bearing (6) is used to bear a part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and radial force of the inner shaft (2) and the rotor (29) of the motor assembly; Along the axial direction of the inner shaft (2), a section of the second half crank (5) away from the first half crank (4) is a first section (7), and the first section (7) and the inner shaft (2) are coaxially arranged; further comprising a connecting member (13), and the first section (7) and the inner shaft (2) can be separated from each other, or can be detachably connected only by the connecting member (13); wherein the connecting member (13) is a bolt or a screw; The bearing assembly comprises a front bearing (27) and a rear bearing (23), wherein the inner shaft (2) is supported by the motor housing (1) via the front bearing (27) and the rear bearing (23), and the bearing outer ring of the front bearing (27) and the bearing outer ring of the rear bearing (23) are respectively clearance-matched with the motor housing (1), and along the axial direction of the inner shaft (2), the front bearing (27) is located between the large bearing (6) and the rear bearing (23); and the size and support strength of the large bearing (6) are greater than the size and support strength of the front bearing (27) and the rear bearing (23); or, The bearing assembly only comprises a rear bearing (23), wherein a section of the inner shaft (2) away from the first half crank (4) is the rear section (21), the rear section (21) of the inner shaft (2) is supported by the motor housing (1) via the rear bearing (23), and the bearing outer ring of the rear bearing (23) is clearance-matched with the motor housing (1); and the size and support strength of the large bearing (6) are higher than those of the rear bearing (23).

2. The oil-free air compressor transmission structure according to claim 1 is characterized in that: The inner shaft (2) is provided with a matching channel (8) and a connecting channel (9) which are coaxial and communicate with each other. The matching channel (8) forms a first opening (10) on one end face of the inner shaft (2), and the first opening (10) is arranged toward the first half crank (4). The connecting channel (9) forms a second opening (11) on the other end face of the inner shaft (2), and the second opening (11) is arranged away from the first half crank (4). A threaded blind hole (12) is axially provided in the first section (7), and the opening of the threaded blind hole (12) is located on the end face of the first section (7) away from the first half crank (4). The connecting member (13) comprises a head (14) and a stem (15), the outer surface of the stem (15) comprises threads, and the maximum cross-sectional diameter of the stem (15) is smaller than the cross-sectional diameter of the head (14), and is also smaller than the cross-sectional diameter of the matching channel (8) and the cross-sectional diameter of the connecting channel (9); When the first section (7) and the inner shaft (2) are detachably connected via the connecting piece (13), the first section (7) is inserted from the first opening (10) into the matching channel (8), and the threaded blind hole (12), the matching channel (8) and the connecting channel (9) are coaxial; the connecting piece (13) passes through the second opening (11), and a portion of the rod portion (15) of the connecting piece (13) is threadedly connected to the threaded blind hole (12), and the head portion (14) of the connecting piece (13) is confined in the connecting channel (9).

3. The oil-free air compressor transmission structure according to claim 2 is characterized in that: A limiting step surface (16) is provided in the connecting passage (9), and when the first section (7) and the inner shaft (2) are detachably connected via the connecting member (13), the head (14) of the connecting member (13) is immovably restricted between the limiting step surface (16) and the second opening (11); It also includes an elastic washer (17). When the first section (7) and the inner shaft (2) are detachably connected via the connecting member (13), the elastic washer (17) is located between the limiting step surface (16) and the head (14) of the connecting member (13) along the axial direction of the connecting passage (9); one end surface of the elastic washer (17) forms surface-to-surface contact with the limiting step surface (16), and the other end surface forms surface-to-surface contact with the end surface of the head (14) of the connecting member (13); the head (14) of the connecting member (13) abuts against the limiting step surface (16) via the elastic washer (17).

4. The oil-free air compressor transmission structure according to claim 2, characterized in that: The outer surface of the first section (7) is configured as a conical outer surface, pointing from the first half crank (4) to the direction of the inner shaft (2), and the conical outer surface of the first section (7) is convergent; The inner surface of the matching channel (8) is a conical inner surface; from the first half crank (4) to the direction of the inner shaft (2), the conical inner surface of the matching channel (8) is convergent; The taper angle of the tapered outer surface of the first section (7) is consistent with the taper angle of the tapered inner surface of the matching channel (8).

5. The oil-free air compressor transmission structure according to claim 4, characterized in that: The connecting channel (9) comprises a coaxially arranged threaded channel (18) and a smooth channel (19), wherein the threaded channel (18) is located between the matching channel (8) and the smooth channel (19), the channel inner wall of the threaded channel (18) has an internal thread for matching with the external thread of the bolt member (20), and the median diameter of the cross section of the threaded channel (18) is greater than the diameter of the cross section of the threaded blind hole (12) and smaller than the diameter of the cross section of the smooth channel (19).

6. The oil-free air compressor transmission structure according to any one of claims 1 to 5, characterized in that: A rear axle hole (22) is provided at one end of the motor housing (1) away from the first half crank (4); along the axial direction of the rear axle hole (22), the rear section (21) of the inner shaft (2) is passed through the rear axle hole (22) and is connected to the rear axle hole (22) via a rear bearing (23), wherein the rear section (21) of the inner shaft (2) is connected to the inner ring of the rear bearing (23) by interference fit; A first step surface (24) is provided on the hole wall of the rear shaft hole (22), and the first step surface (24) extends along the radial direction of the rear shaft hole (22) and along the axial direction of the rear bearing (23), and a clearance fit is formed between the bearing outer ring of the rear bearing (23) and the first step surface (24).

7. The oil-free air compressor transmission structure according to claim 6, characterized in that: Along the radial direction of the rear bearing (23), a clearance fit is formed between the circumferential outer surface of the bearing outer ring of the rear bearing (23) and the circumferential inner wall of the rear shaft hole (22).

8. The oil-free air compressor transmission structure according to claim 7, characterized in that: Along the axial direction of the rear bearing (23), a gap between the outer ring of the rear bearing (23) and the first step surface (24) is filled with a first elastic body (25); and / or, Along the radial direction of the rear bearing (23), a second elastic body (26) is filled in the gap between the circumferential outer surface of the bearing outer ring of the rear bearing (23) and the circumferential inner wall of the rear shaft hole (22).

9. Oil-free air compressor, characterized in that: It comprises the oil-free air compressor transmission structure as described in any one of claims 1-8.

10. An automobile, characterized in that Including the oil-free air compressor described in claim 9.

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