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

Abstract

The present invention relates to the technical field of air compressors for vehicles, and in particular to an oil-free air compressor transmission structure and a vehicle. The oil-free air compressor transmission structure, comprising a motor housing, a motor assembly, and a bearing assembly. The motor assembly is arranged inside of the motor housing. The motor assembly comprises an inner shaft. The inner shaft is rotatably connected to the motor housing by means of the bearing assembly. The oil-free air compressor transmission structure further comprises a box body, a power assembly, and a large bearing. The box body is detachably connected to the motor housing. The power assembly comprises a first half crank and a second half crank. The first half crank and the second half crank are interlocked and connect to form a crank shaft. The crank shaft is rotatably connected to the box body by means of the large bearing. A connector is also comprised, which allows a first section and the inner shaft to be separable from one another, or to be detachably connected only by means of the connector. In the present invention, the first section and the inner shaft can be detachably connected only by means of the connector. The present invention solves the technical problem of how to connect a crank shaft and an inner shaft without the need for a flexible coupling.

Description

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

[0001] The present application relates to the technical field of air compressor for vehicle, in particular to an oil-free air compressor transmission structure, an oil-free air compressor and an automobile. BACKGROUND

[0002] The air compressor is the core equipment of the pneumatic system of the vehicle, which is a device for converting mechanical energy into gas pressure energy, and is a gas pressure generating device for compressed air. In the mechanical field and various production, decoration and manufacturing fields, the air compressor is widely used, and is the source power for driving pneumatic tools.

[0003] The patent document CN201711132468.6 discloses an air compressor in the prior art, which comprises a intercooler group, a high-pressure piston assembly, a low-pressure piston assembly, a piston cylinder, a crankcase and a crankshaft. The air compressor is driven by a motor through an elastic coupling to rotate the crankshaft of the air compressor. The high-pressure piston assembly and the low-pressure piston assembly are placed on the crank and move up and down.

[0004] In the prior art, the crankshaft is connected to the inner shaft of the motor through an elastic coupling. However, the elastic coupling is expensive, which does not meet the current requirement of reducing the cost of the air compressor. If the connection 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, which can meet the current requirement of reducing the cost of the air compressor.

[0005] Meanwhile, in the long-term use of the motor in the prior art, the main wear parts are the internal bearings. Due to the limited installation space inside the motor, the bearing load is small, and the air compressor is subjected to harsh working conditions such as large vibration and frequent start-stop impact, which results in poor service life.

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

[0007] Further, the service life of the motor can be improved. SUMMARY

[0008] In view of the technical problem of how to remove the elastic coupling between the crankshaft and the inner shaft and connect them in the prior art, the present application provides an oil-free air compressor transmission structure, an oil-free air compressor and an automobile.

[0009] The present application is realized by the following technical solutions:

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

[0011] The box is detachably connected with the motor shell, the power assembly comprises a first half-crank and a second half-crank, the first half-crank and the second half-crank are connected with each other and combined into a crankshaft, and the crankshaft is rotatably connected with the box through the large bearing; wherein, along the axial direction of the inner shaft, the second half-crank is located between the first half-crank and the inner shaft;

[0012] The large bearing is sleeved on the crankshaft, and the large bearing is used for bearing a part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and the 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 a first section, and the first section is coaxially arranged with the inner shaft; the first section and the inner shaft are detachable or detachably connected only through the connecting piece; wherein the connecting piece is a bolt or a screw;

[0014] The bearing assembly comprises a front bearing and a rear bearing, wherein the inner shaft is supported by the motor shell through the front bearing and the rear bearing, the bearing outer ring of the front bearing and the bearing outer ring of the rear bearing are respectively gap-fitted with the motor shell, 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 the supporting strength of the large bearing are higher than those of the front bearing and the rear bearing;

[0015] Or,

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

[0017] Further, the inner shaft is internally provided with a matching channel and a connecting channel which are coaxial and communicate with each other, the matching channel forms a first opening at one side end face of the inner shaft, the first opening is arranged towards the first half-crank, the connecting channel forms a second opening at the other side end face of the inner shaft, the second opening is arranged away from the first half-crank, a threaded blind hole is arranged in the first section along the axial direction, and the opening of the threaded blind hole is located at one side end face of the first section away from the first half-crank;

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

[0019] When the first segment and the inner shaft are detachably connected by the connecting piece, the first segment is inserted into the fitting channel from the first opening, and the threaded blind hole, the fitting channel and the connecting channel are coaxial; the connecting piece passes through the second opening, and a part of the shank of the connecting piece is threadedly connected with the threaded blind hole, and the head of the connecting piece is limited in the connecting channel.

[0020] Further, a limiting step surface is arranged in the connecting channel, when the first segment and the inner shaft are detachably connected by the connecting piece, the head of the connecting piece is immovably limited between the limiting step surface and the second opening;

[0021] Further, a limiting step surface is arranged in the connecting channel, when the first segment and the inner shaft are detachably connected by the connecting piece, the head of the connecting piece is immovably limited between the limiting step surface and the second opening;

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

[0023] The inner surface of the fitting channel is a tapered inner surface, and the tapered inner surface of the fitting channel is convergent in the direction from the first half crank to the inner shaft;

[0024] The tapered angle of the tapered outer surface of the first segment is consistent with the tapered angle of the tapered inner surface of the fitting channel.

[0025] Further, the connecting channel comprises a threaded channel and a smooth channel arranged coaxially, wherein the threaded channel is located between the fitting channel and the smooth channel, the inner wall of the threaded channel has internal threads for cooperating with the external threads of the bolt, the cross-sectional diameter of the threaded channel is greater than the cross-sectional diameter of the threaded blind hole and smaller than the cross-sectional diameter of the smooth channel.

[0026] Further, the motor housing is provided with a rear shaft hole away from the end of the first half crank; along the axial direction of the rear shaft hole, the rear segment of the inner shaft is arranged in the rear shaft hole and connected with the rear shaft hole through the rear bearing, wherein the rear segment of the inner shaft is connected with the bearing inner ring of the rear bearing in an interference fit;

[0027] The hole wall of the rear shaft hole is provided with a first step surface, the first step surface extends along the radial direction of the rear shaft hole, and the bearing outer ring of the rear bearing is in clearance fit with the first step surface along the axial direction of the rear bearing.

[0028] Further, along the radial direction of the rear bearing, the circumferential outer surface of the bearing outer ring of the rear bearing is in clearance fit with the circumferential inner wall of the rear shaft hole.

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

[0030] And / or,

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

[0032] The oil-free air compressor comprises the oil-free air compressor transmission structure.

[0033] The automobile comprises the oil-free air compressor.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] 1. In the present application, the first section and the inner shaft can be detachably connected only through the connecting piece, the first section is part of the second half crank, and the second half crank is part of the crankshaft; that is, in the present application, the crankshaft and the inner shaft can be detachably connected only through the connecting piece; therefore, the present application realizes that the coupling is removed, so that the crankshaft and the inner shaft are directly connected only through the connecting piece; in summary, the present application solves the technical problem of how to connect the crankshaft and the inner shaft without the elastic coupling.

[0036] 2、In the prior art, the motor and the crankcase are independent parts, and the inner shaft of the motor and the crankshaft of the crankcase are connected through an elastic coupling. Since there is a gap between the driving end and the driven end of the elastic coupling, the load of the inner shaft and the rotor in the prior art cannot be supported by the double-row angular contact ball bearing in the prior art. Generally, two bearings are arranged inside the motor housing, which are defined as the first bearing and the second bearing. When the motor is connected with 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 bearing inner ring of the first bearing and the bearing inner ring of the second bearing are respectively interference-fitted with the inner shaft, and the bearing outer ring of the first bearing and the bearing outer ring of the second bearing are respectively interference-fitted with the motor housing, so that the inner shaft cannot be displaced in 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 that borne by the second bearing, which causes the first bearing to wear out before the second bearing. The wear of the first bearing reduces the service life of the motor. In the present application, the inner shaft of the motor and the crankshaft of the crankcase are directly connected 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 the crankshaft of the crankcase can be regarded as an extension structure of the inner shaft of the motor. Therefore, the large bearing in the present application can bear the load from the inner shaft and the rotor of the motor through the direct connection of the inner shaft of the motor and the crankshaft of the crankcase through the connecting piece. In the present application, the inner shaft corresponds to the inner shaft of the motor in the prior art. The position of the large bearing corresponds to the position of the double-row angular contact ball bearing in the prior art, the position of the front bearing corresponds to the position of the first bearing in the prior art, and the position of the rear bearing corresponds to the position of the second bearing in the prior art. The size and support strength of the large bearing are much higher than those of the front bearing and the rear bearing, and much higher than those of the first bearing and the second bearing in the prior art.In the first scheme, the bearing inner ring of the front bearing and the bearing inner ring of the rear bearing in the motor are interference fitted with the inner shaft respectively, but the bearing outer ring of the front bearing and the bearing outer ring of the rear bearing in the motor are clearance fitted with the shell respectively, so that the inner shaft can be displaced relative to the shell in operation, the large bearing, the front bearing and the rear bearing in the application jointly bear the load from the 'inner shaft and rotor' of the motor; in this arrangement, the load borne by the front bearing from the 'inner shaft and rotor' of the motor is less than the load borne by the first bearing in the prior art from the'motor shaft and rotor' of the motor; under the condition that the operation time of the motor is the same as the operation time of the motor in the prior art and the operation speed of the motor in the application is the same as the operation speed of the motor in the prior art, the wear degree of the front bearing in the first scheme is lower than the wear degree of the first bearing in the prior art, so that the service life of the front bearing is higher than the service life of the first bearing in the prior art, and the service life of the motor in the application is higher than the service life of the motor in the prior art. In the second scheme, the bearing inner ring of the rear bearing of the motor is interference fitted with the inner shaft, but the bearing outer ring of the rear bearing in the motor is clearance fitted with the motor shell, so that the inner shaft can be displaced relative to the motor shell in the axial direction during operation; since the front bearing is cancelled, the large bearing and the rear bearing jointly 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, under the condition that the operation time of the motor is the same as the operation time of the motor in the 'first scheme' and the operation speed of the motor is the same as the operation speed of the motor in the '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 'first scheme', so that the service life of the large bearing is higher than the service life of the front bearing in the 'first scheme'; since the service life of the front bearing in the 'first scheme' is higher than the service life of the first bearing in the prior art and the service life of the large bearing is higher than the service life of the front bearing in the 'first scheme', the service life of the large bearing in the second scheme is higher than the service life of the first bearing in the prior art, and the service life of the motor in the second scheme is higher than the service life of the motor in the prior art.

[0037] 3、In the application, the rear section of the inner shaft is interference fitted with the bearing inner ring of the rear bearing, i.e. the rear section of the inner shaft and the bearing inner ring of the rear bearing rotate synchronously; the bearing outer ring of the rear bearing and the first step surface are clearance fitted, i.e. there is a gap between the bearing outer ring of the rear bearing and the first step surface; then, due to the clearance between the bearing outer ring of the rear bearing and the first step surface, the position of the inner shaft is adjustable along the axial direction of the inner shaft; the front bearing is also arranged in this way; and the purpose of adjusting the axial position of the inner shaft is achieved.

[0038] 4. In this invention, the outer circumferential surface of the rear bearing's outer ring is clearance-fitted with the inner circumferential wall of the rear shaft hole. This allows the inner shaft to be adjusted radially when it is not aligned with the first section, so that the axis of the inner shaft is collinear with the axis of the first section before assembling the inner shaft with the first section. Therefore, this invention also achieves the goal of making the inner shaft's radial position adjustable.

[0039] 5. In the prior art, a flexible coupling is used to connect the inner shaft of the motor to the crankshaft. However, since the elastic element of the flexible coupling is generally made of plastic products such as polyurethane, its lifespan is short, and long-term use poses a risk of failure such as aging, wear, and cracking. In this invention, since the flexible coupling is avoided, a metal connector is used to connect the inner shaft of the motor to the crankshaft, thus avoiding the above-mentioned problems. Attached Figure Description

[0040] Figure 1 is a cross-sectional schematic diagram of the transmission structure of the oil-free air compressor in Example 1;

[0041] Figure 2 is a schematic diagram of the limiting step surface in Figure 1;

[0042] Figure 3 is an enlarged schematic diagram of region A in Figure 1;

[0043] Figure 4 is an enlarged schematic diagram of region B in Figure 1;

[0044] Figure 5 is an enlarged schematic diagram of region C in Figure 1;

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

[0046] The markings in the figure are: motor housing (1), inner shaft (2), housing (3), first half crank (4), second half crank (5), large bearing (6), first section (7), mating channel (8), connecting channel (9), first opening (10), second opening (11), threaded blind hole (12), connector (13), head (14), rod (15), limiting step surface (16), elastic washer (17), threaded channel (18), smooth channel (19), bolt (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 Implementation

[0047] The technical solutions of the present application will be further described in detail below in conjunction with preferred embodiments and the drawings thereof. In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. In addition, the terms "first", "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, but cannot be understood as a limitation of the present application. Example 1

[0048] As shown in Figure 1, the embodiment proposes a transmission structure of an oil-free air compressor, which comprises a motor shell 1, a motor assembly and a bearing assembly, the motor assembly is arranged inside the motor shell 1, the motor assembly comprises 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 with the motor shell 1 through the bearing assembly; further comprising a box body 3, a power assembly and a large bearing 6, the box body 3 is detachably connected with the motor shell 1, the power assembly comprises a first half crank 4 and a second half crank 5, the first half crank 4 and the second half crank 5 are mutually buckled and connected and combined into a crankshaft, the crankshaft is rotatably connected with the box body 3 through 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; characterized in that the large bearing 6 is sleeved on the crankshaft, the large bearing 6 is used for bearing a part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and the radial force of the inner shaft 2 and the rotor 29 of the motor assembly, such as gravity, start-stop impact force, magnetic field pulling force, vehicle random vibration, assembly eccentric force and the like; 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, the first section 7 and the inner shaft 2 are coaxially arranged; further comprising a connecting piece 13, the first section 7 and the inner shaft 2 can be separated from each other or are detachably connected only through the connecting piece 13; wherein the connecting piece 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 shell 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 gap-fitted with the motor shell 1, 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 the supporting 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 comprises the rear bearing 23, wherein a section of the inner shaft 2 away from the first half crank 4 is a rear section 21, the rear section 21 of the inner shaft 2 is supported by the motor shell 1 through the rear bearing 23, the bearing outer ring of the rear bearing 23 is gap-fitted with the motor shell 1; and the size and the supporting strength of the large bearing 6 are higher than those of the rear bearing 23.

[0049] The motor assembly comprises the inner shaft 2, which is an axially extending shaft body structure; the motor assembly further comprises the rotor 29, which is sleeved on the outer surface of the inner shaft 2 and fixed with the inner shaft 2; the motor assembly further comprises the stator 30, which is connected with the motor shell 1 and arranged around the rotor 29; the motor assembly further comprises the bearing assembly, the inner shaft 2 is rotatably connected with the motor shell 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 shell 1 through the bearing assembly; when the stator 30 generates a rotating magnetic field, the inner shaft 2 is coaxially and synchronously rotated by the rotor 29.

[0050] The power assembly comprises a first half-crank 4 and a second half-crank 5, the first half-crank 4 and the second half-crank 5 are similar in structure but not identical, the first half-crank 4 and the second half-crank 5 are connected to each other in a clamping manner and combined into a crankshaft, and the connection manner can refer to the disclosure of the patent document CN202220104964.0; the power assembly further comprises a counterweight part 31, the counterweight part 31 is detachably connected with the first half-crank 4 and used for balancing the reciprocating inertial torque of the rotation of the crankshaft; the power assembly further comprises a low-pressure piston connecting rod assembly 32 and a low-pressure bearing 33, the low-pressure piston connecting rod assembly 32 is rotatably connected with the second half-crank 5 through the low-pressure bearing 33; the power assembly further comprises a high-pressure piston connecting rod assembly 34 and a high-pressure bearing 35, the high-pressure piston connecting rod assembly 34 is rotatably connected with 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 is 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 with the first half-crank 4; another section of the second half-crank 5, i.e., the first section 7, extends out of the box body 3 and is detachably connected with the inner shaft 2 only through the connecting piece 13.

[0052] As shown in FIGS. 1-3, between the first section 7 and the inner shaft 2, only the detachable connection structure formed by the connecting piece 13, specifically: the inner shaft 2 is internally 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 side end face of the inner shaft 2, the first opening 10 is arranged towards the first half-crank 4, the connecting channel 9 forms a second opening 11 on the other side end face of the inner shaft 2, the second opening 11 is arranged away from the first half-crank 4, the first section 7 is axially provided with a threaded blind hole 12, the opening of the threaded blind hole 12 is located on the side end face of the first section 7 away from the first half-crank 4; the connecting piece 13 has a head part 14 and a rod part 15, the outer surface of the rod part 15 is provided with threads, the maximum cross-sectional diameter of the rod part 15 is smaller than the cross-sectional diameter of the head part 14, and also smaller than the cross-sectional diameters of the matching channel 8 and 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, 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 part 15 of the connecting piece 13 is threadedly connected with the threaded blind hole 12, and the head part 14 of the connecting piece 13 is limited in the connecting channel 9.

[0053] In this embodiment, by setting the matching channel 8, the connecting channel 9 inside the inner shaft 2, and the threaded blind hole 12 inside the first section 7, the threaded blind hole 12, the matching channel 8, and the connecting channel 9 are coaxial during assembly, the first section 7 is inserted into the matching channel 8, and the connecting piece 13 moves in the space jointly limited and enclosed by the hole wall of the threaded blind hole 12, part of the channel inner wall of the matching channel 8, and the channel inner wall of the connecting channel 9, and the first section 7 is detachably connected with the inner shaft 2, that is, the first section 7 is detachably connected with the inner shaft 2 through the connecting piece 13, and the connecting piece 13 only occupies the internal space of the first section 7 and the inner shaft 2, thereby avoiding occupying the external space of the first section 7 and the inner shaft 2.

[0054] The scheme in which the bearing assembly includes both the front bearing 27 and the rear bearing 23 is the first scheme, in which the combination of the inner shaft 2 and the rotor 29 is three-point supported by the large bearing 6, the front bearing 27, and the rear bearing 23; the scheme in which the bearing assembly includes only the rear bearing 23 is the second scheme, which is mainly applicable to the models of small-displacement air compressors. Since the rotor shaft of the small-displacement air compressor has a short span, the front bearing 27 can be cancelled, so that the combination of the power assembly and the motor assembly is two-point supported by the large bearing 6 and the rear bearing 23, which can meet the use requirements.

[0055] In the first scheme and the second scheme, the bearing assembly includes the rear bearing 23, and the bearing outer ring of the rear bearing 23 is gap-fitted with the motor housing 1. In the two schemes, the specific structure in which the bearing outer ring of the rear bearing 23 is gap-fitted with the motor housing 1 is as follows.

[0056] As shown in FIGS. 1 and 4, specifically, the motor housing 1 is provided with a rear shaft hole 22 at the end 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 arranged in the rear shaft hole 22 and connected with the rear shaft hole 22 through the rear bearing 23, wherein the rear section 21 of the inner shaft 2 is connected with the bearing inner ring of the rear bearing 23 in an interference fit; the hole wall of the rear shaft hole 22 is provided with a first step surface 24, 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, the bearing outer ring of the rear bearing 23 is gap-fitted with the first step surface 24. In addition, along the radial direction of the rear bearing 23, the bearing outer ring circumferential outer surface of the rear bearing 23 is gap-fitted with the circumferential inner wall of the rear shaft hole 22.

[0057] As known from the foregoing, in the first scheme, the bearing outer ring of the front bearing 27 is gap-fitted with the motor housing 1; specifically:

[0058] As shown in Fig. 1, Fig. 5, preferably, the bearing assembly further comprises a front bearing 27, the inner shaft 2 has a front section 36 along the axial direction of the inner shaft 2, the inner shaft 2 is towards the first half-crank 4; the motor housing 1 has a front shaft hole 28 at one end of the motor housing 1, the front section 36 of the inner shaft 2 is arranged in the front shaft hole 28 along the axial direction of the front shaft hole 28, and the front section 36 of the inner shaft 2 is connected to the front shaft hole 28 through the front bearing 27.

[0059] As shown in Fig. 1, Fig. 5, the front section 36 of the inner shaft 2 is connected to the bearing inner ring of the front bearing 27 in an interference fit, the hole wall of the front shaft hole 28 is provided with a second stepped surface 37, the second stepped surface 37 extends along the radial direction of the front shaft hole 28, and the bearing outer ring of the front bearing 27 is in clearance fit with the second stepped surface 37. In addition, the circumferential outer surface of the bearing outer ring of the front bearing 27 is in clearance fit with the circumferential inner wall of the front shaft hole 28.

[0060] The front bearing 27 is arranged in a similar manner as the bearing outer ring of the rear bearing 23 is in clearance fit with the motor housing 1, and the front bearing 27 and the rear bearing 23 are arranged in a mirror image symmetry.

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

[0062] In the embodiment, the first section 7 and the inner shaft 2 are detachably connected only through the connecting piece 13, the first section 7 is part of the second half-crank 5, and the second half-crank 5 is part of the crankshaft. That is, in the embodiment, the crankshaft and the inner shaft 2 are detachably connected only through the connecting piece 13. Therefore, the embodiment realizes that the coupling is removed, and the crankshaft and the inner shaft 2 are directly connected only through the connecting piece 13. In summary, the embodiment solves the technical problem of how to connect the crankshaft and the inner shaft without the elastic coupling.

[0063] Further, the connecting piece 13 is a bolt or a screw, which is made of metal. The processing cost or procurement cost of the connecting piece 13 is much lower than that of the coupling. Compared with the prior art, the embodiment also achieves the purpose of saving cost.

[0064] In the prior art, the motor and the crankcase are independent parts, and the inner shaft of the motor and the crankshaft of the crankcase are connected through an elastic coupling. Since there is a gap between the driving end and the driven end of the elastic coupling, the load of the inner shaft and the rotor in the prior art cannot be supported by the double-row angular contact ball bearing in the prior art. Generally, two bearings are arranged inside the motor housing, which are defined as the first bearing and the second bearing. When the motor is connected with 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 bearing inner ring of the first bearing and the bearing inner ring of the second bearing are respectively in interference fit with the inner shaft, and the bearing outer ring of the first bearing and the bearing outer ring of the second bearing are respectively in interference fit with the motor housing, so that the inner shaft cannot be displaced in 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 that borne by the second bearing, which causes the first bearing to wear out before the second bearing. The wear of the first bearing reduces the service life of the motor.

[0065] In the embodiment, the inner shaft 2 of the motor is directly connected with 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 the crankshaft of the crankcase can be regarded as an extension structure of the inner shaft 2 of the motor. Therefore, in the embodiment, the large bearing 6 can bear the load from the inner shaft 2 and the rotor 29 of the motor through the direct connection of the inner shaft 2 of the motor and the crankshaft of the crankcase through the connecting piece 13.

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

[0067] In the first scheme, the bearing inner ring of the front bearing 27 and the bearing inner ring of the rear bearing 23 in the motor are interference fitted with the inner shaft 2 respectively, but the bearing outer ring of the front bearing 27 and the bearing outer ring of the rear bearing 23 in the motor are clearance fitted with the shell respectively, so that the inner shaft 2 can be displaced relative to the shell in operation, the large bearing 6, the front bearing 27 and the rear bearing 23 in the embodiment jointly bear the load from the 'inner shaft 2 and rotor 29' of the motor; in this arrangement, the load borne by the front bearing 27 from the 'inner shaft 2 and rotor 29' of the motor is less than the load borne by the first bearing in the prior art from the'motor shaft and rotor 29' of the motor; under the condition that the operation time of the motor is the same as that of the motor in the prior art and the working rotational speed of the motor in the embodiment is the same as that 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 service life of the front bearing 27 is higher than that of the first bearing in the prior art, and the service life of the motor in the embodiment is higher than that of the motor in the prior art.

[0068] In the second scheme, the bearing inner ring of the rear bearing 23 of the motor is interference fitted with the inner shaft 2, but the bearing outer ring of the rear bearing 23 in the motor is clearance fitted with the motor shell 1, so that the inner shaft 2 can be displaced relative to the motor shell 1 along the axial direction in operation; since the front bearing 27 is cancelled, the large bearing 6 and the rear bearing 23 jointly 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 those of the cancelled front bearing 27, under the condition that the operation time of the motor is the same as that of the motor in the 'first scheme' and the operation rotational speed of the motor is the same as that of the 'first scheme', the wear degree of the large bearing 6 in the second scheme is lower than the wear degree of the front bearing 27 in the 'first scheme', so that the service life of the large bearing 6 is higher than that of the front bearing 27 in the first scheme; since the service life of the front bearing 27 in the 'first scheme' is higher than that of the first bearing in the prior art and the service life of the large bearing 6 is higher than that of the front bearing 27 in the first scheme, the service life of the large bearing 6 in the second scheme is higher than that of the first bearing in the prior art, and the service life of the motor in the second scheme is higher than that of the motor in the prior art.

[0069] Further, in the first scheme in the embodiment, the inner shaft 2 is rotatably connected with the motor housing 1 through the front bearing 27 and the rear bearing 23 respectively; therefore, a part of the motor core load required to be borne by the bearing assembly is shared by the front bearing 27 and the rear bearing 23, and the load borne by the front bearing 27 and the rear bearing 23 is further reduced, which is more conducive to improving the service life of the front bearing 27 and the rear bearing 23.

[0070] Further, in the prior art, the elastic coupling is used to connect the inner shaft of the motor with the crankshaft, and the elastic body of the elastic coupling is generally made of polyurethane or other plastic products, which has poor service life and has the risk of aging, wear and tear, and rupture in long-term use; in the embodiment, the elastic coupling is avoided, and the connecting piece 13 made of metal is used to connect the inner shaft of the motor with the crankshaft, so that the above problems can also be avoided.

[0071] Further, when the oil-free air compressor transmission structure is assembled, the motor assembly and the bearing assembly are usually assembled into the motor housing 1, and the power assembly and the large bearing 6 are usually assembled into the box body 3, and then the motor housing 1 and the box body 3 are connected and buckled to make the first section 7 and the inner shaft 2 coaxially connected; however, in actual assembly, after the motor housing 1 and the box body 3 are buckled, the assembly position between the inner shaft 2 and the first section 7 along the axial direction of the inner shaft 2 is often not matched, resulting in a gap between the tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8, i.e., the tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8 cannot be tightly attached.

[0072] In the embodiment, the rear section 21 of the inner shaft 2 is connected with the bearing inner ring of the rear bearing 23 in interference fit, i.e., the rear section 21 of the inner shaft 2 and the bearing inner ring of the rear bearing 23 rotate synchronously; the bearing outer ring of the rear bearing 23 and the first step surface 24 are clearance fit, i.e., there is a gap between the bearing outer ring of the rear bearing 23 and the first step surface 24; therefore, due to the gap between the bearing 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, as shown in FIG. 4, when the inner shaft 2 needs to move to the right in FIG. 4, the inner shaft 2 drives the bearing inner ring of the rear bearing 23 to move to the right, and the bearing inner ring of the rear bearing 23 is connected with the bearing outer ring of the rear bearing 23, which causes the bearing outer ring of the rear bearing 23 to also move to the right; thereby achieving the purpose of adjusting the axial position of the inner shaft 2.

[0073] Further, after the motor housing 1 and the box body 3 are buckled, the inner shaft 2 and the first section 7 are often not coaxial along the radial direction of the inner shaft 2.

[0074] In the embodiment, the outer circumferential surface of the outer ring of the rear bearing 23 is in clearance fit with the inner circumferential wall of the rear shaft hole 22. This allows the inner shaft 2 to be adjusted in radial direction when the inner shaft 2 is not coaxial with the first section 7, so that the axis of the inner shaft 2 is aligned with the axis of the first section 7, and then the inner shaft 2 and the first section 7 are assembled together. Therefore, the purpose of adjusting the radial position of the inner shaft 2 is also achieved in the embodiment.

[0075] It is mentioned above that the head 14 of the connecting piece 13 is limited in the connecting channel 9. Specifically, in the embodiment, a limiting step surface 16 is arranged in the connecting channel 9, and when the first section 7 and the inner shaft 2 are detachably connected by the connecting piece 13, the head 14 of the connecting piece 13 is limited between the limiting step surface 16 and the second opening 11 and cannot move.

[0076] Generally, the limiting step surface 16 is difficult to be machined as a plane due to the limitation of machining conditions, and the side end surface of the head 14 of the connecting piece 13 towards the limiting step surface 16 is generally a plane, which easily causes the contact between the head 14 of the connecting piece 13 and the limiting step surface 16 to be point-to-point contact or line-to-line contact. This results in too small contact area and too small friction between the head 14 of the connecting piece 13 and the limiting step surface 16, and the relative slip between the head 14 and the limiting step surface 16 during the starting of the motor and the rotation of the inner shaft 2, so that the inner shaft 2 and the second half-crank 5 cannot rotate synchronously. Therefore, how to increase the friction between the head 14 of the connecting piece 13 and the limiting step surface 16 is a technical problem to be solved, which is solved by the following technical scheme.

[0077] As shown in FIGS. 1-3, the oil-free air compressor transmission structure of the embodiment further comprises an elastic washer 17, which 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 when the first section 7 and the inner shaft 2 are detachably connected by the connecting piece 13. One side end surface of the elastic washer 17 is in surface-to-surface contact with the limiting step surface 16, and the other side end surface is in surface-to-surface contact with the end surface 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 washer 17 has elasticity, and the material thereof can be selected from known materials in the prior art, such as rubber material, which is not limited herein.

[0079] In the embodiment, the side end face of the elastic washer 17 towards the limiting step face 16 is configured to be consistent with the shape of the limiting step face 16, for example, a curved surface, so that the side end face of the elastic washer 17 towards the limiting step face 16 forms a surface-to-surface contact with the limiting step face 16; and the side end face of the elastic washer 17 towards the head 14 of the connecting piece 13 is configured to be a plane consistent with the end face of the head 14, so that the side end face of the elastic washer 17 towards the head 14 of the connecting piece 13 forms a surface-to-surface contact with the head 14 of the connecting piece 13.

[0080] In the embodiment, the elastic washer 17 is arranged between the head 14 of the connecting piece 13 and the limiting step face 16, and the head 14 of the connecting piece 13 and the limiting step face 16 respectively form a surface-to-surface contact with the elastic washer 17, which causes the inner shaft 2 to drive the elastic washer 17 to rotate synchronously through the friction between the limiting step face 16 and the elastic washer 17 during the rotation of the inner shaft 2, and then the connecting piece 13 is driven to rotate synchronously with the inner shaft 2 through the friction between the elastic washer 17 and the head 14 of the connecting piece 13, and then the crankshaft is driven to rotate synchronously with the inner shaft 2 through the threaded connection relationship between the connecting piece 13 and the threaded blind hole 12 in the first segment 7 of the second half crank 5.

[0081] In the embodiment, the elastic washer 17 is arranged between the head 14 of the connecting piece 13 and the limiting step face 16, and the elastic washer 17 respectively forms a surface-to-surface contact with the head 14 of the connecting piece 13 and the limiting step face 16, so that the head 14 of the connecting piece 13 and the limiting step face 16 increase the friction through the elastic washer 17; therefore, the embodiment solves the technical problem of how to increase the friction between the head 14 of the connecting piece 13 and the limiting step face 16.

[0082] As shown in FIG. 1, further, the embodiment further includes the following technical solutions: the outer surface of the first segment 7 of the oil-free air compressor transmission structure is configured to be a tapered outer surface, which is directed from the first half crank 4 to the inner shaft 2, and the tapered outer surface of the first segment 7 is convergent; the inner surface of the matching channel 8 is a tapered inner surface; the tapered inner surface of the matching channel 8 is convergent in the direction from the first half crank 4 to the inner shaft 2; and the taper angle of the tapered outer surface of the first segment 7 is consistent with the taper angle of the tapered inner surface of the matching channel 8.

[0083] The purposes of such arrangement mainly include two aspects:

[0084] In the connecting process of 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 gradual insertion of 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 tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8 are both convergent, which causes the tapered inner surface of the matching channel 8 to guide the tapered outer surface of the first section 7, so that the first section 7 is coaxially aligned with the inner shaft 2 during the blind insertion of the first section 7.

[0085] In the second aspect, after the first section 7 of the second half crank 5 is inserted into the matching channel 8 of the inner shaft 2, the rod part of the connecting piece 13 is screwed with the threaded blind hole 12 of the first section 7, so that the tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8 are tightly attached to each other, thereby increasing the contact area between the first section 7 and the matching channel 8 and the friction therebetween.

[0086] Further, in the first and second solutions mentioned above, the bearing outer ring of the rear bearing 23 and the first step surface 24 are in clearance fit along the axial direction of the rear bearing 23, and 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 are in clearance fit along the radial direction of the rear bearing 23, which causes the friction between the bearing outer ring of the rear bearing 23 and the hole wall of the rear shaft hole 22 to be too small, and the bearing outer ring of the rear bearing 23 is prone to idling. Once the bearing outer ring of the rear bearing 23 idles, the bearing outer ring of the rear bearing 23 will slide and rub against the rear shaft hole 22, causing the surface of the bearing outer ring of the rear bearing 23 to be worn. Therefore, how to increase the friction between the bearing outer ring of the rear bearing 23 and the hole wall of the rear shaft hole 22 is a technical problem to be solved, which is solved by the following technical solution.

[0087] The gap between the bearing outer ring of the rear bearing 23 and the first step surface 24 along the axial direction of the rear bearing 23 is filled with a first elastic body 25, and / or 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 along the radial direction of the rear bearing 23 is filled with a second elastic body 26.

[0088] The first elastic body 25 can be a rubber gasket, a metal corrugated gasket, or the like, which can be deformed along the axial direction of the rear bearing 23. In this embodiment, the gap between the bearing outer ring of the rear bearing 23 and the first step surface 24 along the axial direction of the rear bearing 23 is filled with the first elastic body 25, thereby increasing the friction between the side surface of the bearing outer ring of the rear bearing 23 and the first step surface 24 through the first elastic body 25.

[0089] The second elastic body 26 can be an O-ring structure, which can be extruded and deformed along the radial direction of the rear bearing 23. In this embodiment, 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 is filled with the second elastic body 26, so that the friction 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 is increased by the second elastic body 26.

[0090] In summary, in this embodiment, the first elastic body 25 is filled in the gap between the bearing outer ring of the rear bearing 23 and the first step surface 24, so that the friction between the side surface of the bearing outer ring of the rear bearing 23 and the first step surface 24 is increased; and / or, the 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, so that the friction 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 is increased; thereby, the problem that the bearing outer ring of the rear bearing 23 rotates relative to the rear shaft hole 22 is avoided.

[0091] In the first scheme, correspondingly, a third elastic body is filled in the gap between the bearing outer ring of the front bearing 27 and the second step surface 37 along the axial direction of the front bearing 27; and / or, a fourth elastic body is filled in the gap between the circumferential outer surface of the bearing outer ring of the front bearing 27 and the circumferential inner wall of the front shaft hole 28 along the radial direction of the front bearing 27. 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. Embodiment 2

[0092] The oil-free air compressor transmission structure of this embodiment has most of the same structure as that of embodiment 1, and the content of this embodiment focuses on the parts different from those in embodiment 1.

[0093] In embodiment 1, the first section 7 and the inner shaft 2 are detachably connected by the connecting piece 13, and the tapered outer surface of the first section 7 is in close 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 connecting piece 13 should be first unscrewed and removed, and then the tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8 are separated from each other; in order to facilitate the separation of the tapered outer surface of the first section 7 and the tapered inner surface of the matching channel 8 from each other, this embodiment further includes the following technical scheme:

[0095] As shown in Fig. 6, the connecting channel 9 comprises a threaded channel 18 and a smooth channel 19 coaxially arranged, wherein the threaded channel 18 is located between the mating channel 8 and the smooth channel 19, the inner wall of the threaded channel 18 has internal threads for mating with the external threads of the bolt 20, the cross-sectional diameter of the threaded channel 18 is greater than the diameter of the cross-section of the threaded blind hole 12 and less than the diameter of the cross-section of the smooth channel 19.

[0096] The external surface of the bolt 20 is threaded, and in this embodiment, the bolt 20 is a coarse bolt, the thread diameter of which is greater than the thread diameter of the rod 15 of the connecting piece 13 in Embodiment 1.

[0097] When disassembled, the connecting piece 13 is unscrewed and removed, one end of the bolt 20 passes through the threaded channel 18 and abuts against the end surface of the first section 7, and a part of the external surface of the bolt 20 is threadedly engaged with the internal threads of the threaded channel 18, the bolt 20 is screwed in the direction of the smooth channel 19 pointing to the threaded channel 18, so that the bolt 20 pushes the side end surface of the first section 7 located in the mating channel 8, thereby separating the tapered external surface of the first section 7 and the tapered internal surface of the mating channel 8. Embodiment 3

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

[0099] This embodiment proposes an automobile, which comprises the oil-free air compressor mentioned in Embodiment 3.

[0100] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An oil-free air compressor transmission structure, comprising a motor housing (1), a motor assembly and a bearing assembly, 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), the inner shaft (2) is rotatably connected with the motor housing (1) through the bearing assembly; It also includes the box (3), power components, large bearing (6), box (3) and motor shell (1) can be detachable connection, power components including first half crank (4), second half crank (5), first half crank (4) and second half crank (5) are buckled to each other and combined into a crankshaft, the crankshaft is rotatably connected with the box (3) through 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); Characterized in that a large bearing (6) is sleeved on the crankshaft, the large bearing (6) is used for bearing a part of the load of the motor assembly, wherein the load of the motor assembly is the axial force and the radial force of the inner shaft (2) and the rotor (29) of the motor assembly; Along the axial direction of the inner shaft (2), the first segment (7) of the second half crank (5) away from the first half crank (4) is coaxially arranged with the inner shaft (2); further comprising a connecting piece (13), the first segment (7) and the inner shaft (2) can be separated from each other, or are detachably connected only through the connecting piece (13); wherein the connecting piece (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) 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 gap-fitted with the motor housing (1), 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 supporting 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 comprises a rear bearing (23), wherein the rear segment (21) of the inner shaft (2) away from the first half crank (4) is supported by the motor housing (1) through the rear bearing (23), the bearing outer ring of the rear bearing (23) is gap-fitted with the motor housing (1); and the size and supporting 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, characterized by, The inner shaft (2) is internally 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 side end face of the inner shaft (2), the first opening (10) is arranged towards the first half crank (4), the connecting channel (9) forms a second opening (11) on the other side end face of the inner shaft (2), the second opening (11) is arranged away from the first half crank (4), the first segment (7) is internally provided with a threaded blind hole (12) along the axial direction, the opening of the threaded blind hole (12) is located on the side end face of the first segment (7) away from the first half crank (4); The connecting piece (13) has a head portion (14) and a rod portion (15), the outer surface of the rod portion (15) has threads, the maximum cross-sectional diameter of the rod portion (15) is smaller than the cross-sectional diameter of the head portion (14), and 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 by the connecting piece (13), the first section (7) is inserted into the matching channel (8) from the first opening (10), 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 portion (15) of the connecting piece (13) is threadedly connected with the threaded blind hole (12), and the head portion (14) of the connecting piece (13) is limited in the connecting channel (9).

3. The oil-free air compressor transmission structure according to claim 2, characterized by, A limiting step surface (16) is arranged in the connecting channel (9), when the first section (7) and the inner shaft (2) are detachably connected by the connecting piece (13), the head portion (14) of the connecting piece (13) is inactively limited between the limiting step surface (16) and the second opening (11); Further comprising an elastic washer (17), when the first section (7) and the inner shaft (2) are detachably connected by the connecting piece (13), along the axial direction of the connecting channel (9), the elastic washer (17) is located between the limiting step surface (16) and the head portion (14) of the connecting piece (13); one side end surface of the elastic washer (17) forms a surface-to-surface contact with the limiting step surface (16), and the other side end surface forms a surface-to-surface contact with the end surface of the head portion (14) of the connecting piece (13); the head portion (14) of the connecting piece (13) abuts against the limiting step surface (16) through the elastic washer (17).

4. The oil-free air compressor transmission structure according to claim 2, characterized by, The outer surface of the first section (7) is configured as a tapered outer surface, and the tapered 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 tapered inner surface, and the tapered inner surface of the matching channel (8) is convergent in the direction from the first half crank (4) to the inner shaft (2); 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 by, The connecting channel (9) comprises a threaded channel (18) and a smooth channel (19) arranged coaxially, wherein the threaded channel (18) is located between the matching channel (8) and the smooth channel (19), the inner wall of the threaded channel (18) has internal threads for cooperating with external threads of a bolt (20), the cross-sectional diameter 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 1-5, characterized in that, The motor housing (1) is provided with a rear shaft hole (22) at one end 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 arranged in the rear shaft hole (22) and connected with the rear shaft hole (22) through a rear bearing (23), wherein the rear section (21) of the inner shaft (2) is connected with the bearing inner ring of the rear bearing (23) in an interference fit; The hole wall of the rear shaft hole (22) is provided with a first step surface (24), the first step surface (24) extends along the radial direction of the rear shaft hole (22), and the bearing outer ring of the rear bearing (23) is in clearance fit with the first step surface (24) along the axial direction of the rear bearing (23).

7. The oil-free air compressor drive structure according to claim 6, wherein Along the radial direction of the rear bearing (23), 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) are in clearance fit.

8. The oil-free air compressor drive structure according to claim 7, wherein Along the axial direction of the rear bearing (23), the gap between the bearing outer ring of the rear bearing (23) and the first step surface (24) is filled with the first elastic body (25); And / or, Along the radial direction of the rear bearing (23), 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) is filled with the second elastic body (26).

9. An oil-free air compressor characterized by The oil-free air compressor transmission structure of any one of claims 1-8.

10. An automobile characterized by The oil-free air compressor of claim 9.

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