Shell-less motor and air compressor

Abstract

The utility model provides a kind of shellless motor and air compressor, including stator assembly, rotor assembly, front end cover and rear end cover, stator assembly is exposed to air, stator assembly has the stator recess and / or stator heat dissipation channel for heat dissipation, rotor assembly is set in stator assembly, rotor assembly has the rotor recess and / or rotor heat dissipation channel for heat dissipation, front end cover and rear end cover are respectively detachably set in the both ends of stator assembly. By being exposed to air directly in stator assembly, no longer set shell, make overall structure more simplified, reduce manufacturing cost and assembly difficulty, it is also convenient to post-cleaning and maintenance simultaneously, and recess and heat dissipation channel are set on stator assembly and rotor assembly, so that motor can directly dissipate heat to air in working process, enhance the heat dissipation effect of stator assembly and rotor assembly, to avoid the structure complex, high cost and maintenance difficult of motor in prior art rely on oil cooling structure and other problems.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and more specifically, to a casing-less motor and an air compressor. Background Technology

[0002] Air compressors, as general-purpose power equipment, are widely used in industrial fields. Among them, screw air compressors are gradually replacing traditional piston air compressors due to their advantages such as high efficiency, low energy consumption, and compact structure. As the requirements for cleanliness, ventilation, dust control, and noise levels in some industrial scenarios continue to increase, the performance requirements for air compressor drive motors are also increasing, mainly reflected in starting torque, working efficiency, heat dissipation performance, and speed regulation capability.

[0003] In the existing technology, some motors in equipment such as air compressors are cooled by oil, which requires the installation of oil inlet and outlet holes on the outside of the casing. This makes the overall structure complex and costly. Utility Model Content

[0004] This invention provides a casing-less motor and air compressor to solve the problem of high cost of motors using oil cooling in the prior art.

[0005] To address the aforementioned problems, according to one aspect of this utility model, a casing-less motor is provided, comprising a stator assembly, a rotor assembly, a front end cover, and a rear end cover. The stator assembly is exposed to the air and has stator grooves and / or stator heat dissipation channels for heat dissipation. The rotor assembly is disposed within the stator assembly and has rotor grooves and / or rotor heat dissipation channels for heat dissipation. The front end cover and the rear end cover are detachably disposed at both ends of the stator assembly.

[0006] Furthermore, the stator assembly includes a stator core and a stator winding wound on the stator core, and the outer surface of the stator core is provided with a plurality of stator grooves in the circumferential direction.

[0007] Furthermore, the stator assembly includes a stator core and a stator winding wound on the stator core. The stator core has multiple stator through holes that axially penetrate the stator core. The multiple stator through holes are distributed along the circumference of the stator core, and each stator through hole forms a stator heat dissipation channel.

[0008] Furthermore, the rotor assembly includes a rotor core and a rotor shaft disposed inside the rotor core, and the outer surface of the rotor core is provided with a plurality of rotor grooves circumferentially.

[0009] Furthermore, the rotor assembly includes a rotor core and a rotor shaft disposed inside the rotor core. The rotor core has multiple rotor through holes that axially penetrate the rotor core. The multiple rotor through holes are distributed along the circumference of the rotor core, and each rotor through hole forms a rotor heat dissipation channel.

[0010] Furthermore, the rotor assembly includes a rotor core and a rotor shaft disposed inside the rotor core. The rotor assembly also includes a rotor baffle and multiple blades. The rotor baffle is annular and is fitted onto the portion of the rotor shaft that protrudes from the rotor core and is connected to the rotor core. The multiple blades are disposed circumferentially on the rotor baffle.

[0011] Furthermore, the rear end cover includes a connecting structure and a heat dissipation structure. The connecting structure is detachably connected to one end of the stator assembly, and the heat dissipation structure is connected to the connecting structure. The heat dissipation structure covers the end of the rotor assembly and at least dissipates heat from the rotor assembly.

[0012] Furthermore, the connection structure includes an annular plate and multiple fasteners. The annular plate has multiple connection holes in its circumferential direction, and the stator assembly has multiple threaded holes in its circumferential direction at the end facing the rear end cover. Each fastener passes through a connection hole and is threadedly connected to a threaded hole. The heat dissipation structure includes an annular wall and a heat sink. One end of the annular wall is connected to the annular plate, and the other end of the annular wall is connected to the heat sink. The heat sink has multiple heat dissipation holes.

[0013] Furthermore, the front end cover includes a first annular component, a second annular component, a plurality of first bolts, and a plurality of second bolts. The first annular component is used to connect with the compressor head of the air compressor, and the second annular component is connected with the stator assembly. The outer diameter of the first annular component is larger than the outer diameter of the second annular component. The first annular component and the second annular component are fixedly connected. The first annular component has a plurality of compressor head fixing holes in its circumferential direction, and the second annular component has a plurality of stator fixing holes in its circumferential direction. The first bolts pass through the compressor head fixing holes and are connected to the compressor head, and the second bolts pass through the stator fixing holes and are connected to the stator assembly.

[0014] According to another aspect of the present invention, an air compressor is provided, the air compressor including a compressor head and the aforementioned casing-less motor, the compressor head and the front end cover of the casing-less motor being connected.

[0015] By applying the technical solution of this utility model, the stator assembly is directly exposed to the air, eliminating the need for a housing. This simplifies the overall structure, reduces manufacturing costs and assembly difficulty, and facilitates subsequent cleaning and maintenance. Grooves and heat dissipation channels are provided on the stator and rotor assemblies, allowing the motor to directly dissipate heat into the air during operation, enhancing the heat dissipation effect of the stator and rotor assemblies. This avoids the problems of complex structure, high cost, and difficult maintenance associated with existing oil-cooled motors. Furthermore, both the front and rear covers are detachably located at both ends of the stator assembly, ensuring stable support, sealing, and protection of the motor. This also allows for easy disassembly and assembly when maintenance or replacement of parts is needed, improving the maintainability of the motor. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0017] Figure 1 A schematic diagram of the structure of the casing-less motor provided in an embodiment of the present invention is shown;

[0018] Figure 2 It shows Figure 1 Schematic diagram of the middle stator assembly;

[0019] Figure 3 It shows Figure 1 Schematic diagram of the structure of the intermediate rotor assembly;

[0020] Figure 4 It shows Figure 1 Schematic diagram of the front end cap structure;

[0021] Figure 5 It shows Figure 1 Schematic diagram of the middle and rear end caps;

[0022] Figure 6 A schematic diagram of a caseless motor provided by an embodiment of the present invention, showing heat dissipation through stator recesses, is shown.

[0023] Figure 7 A schematic diagram of a caseless motor provided by an embodiment of the present invention dissipating heat through a stator heat dissipation channel is shown.

[0024] Figure 8 A schematic diagram of a casing-less motor provided by an embodiment of the present invention, showing heat dissipation through rotor grooves, is shown.

[0025] Figure 9 A schematic diagram of a casing-less motor provided by an embodiment of the present invention, showing heat dissipation through a rotor heat dissipation channel, is shown.

[0026] The above figures include the following reference numerals:

[0027] 10. Stator assembly; 11. Stator recess; 12. Stator heat dissipation channel;

[0028] 13. Stator core; 14. Stator winding; 15. Stator through hole;

[0029] 20. Rotor assembly; 21. Rotor groove; 22. Rotor heat dissipation channel;

[0030] 23. Rotor core; 24. Rotor shaft; 25. Rotor through hole; 26. Rotor baffle; 27. Blade;

[0031] 30. Front end cover; 31. First annular component; 311. Head fixing hole;

[0032] 32. Second annular component; 321. Stator fixing hole;

[0033] 40. Rear end cover; 41. Connecting structure; 411. Annular plate; 412. Connecting hole;

[0034] 42. Heat dissipation structure; 421. Annular wall; 422. Heat dissipation plate; 4221. Heat dissipation holes. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0036] like Figures 1 to 9 As shown, an embodiment of the present invention provides a casing-less motor, including a stator assembly 10, a rotor assembly 20, a front end cover 30, and a rear end cover 40. The stator assembly 10 is exposed to the air and has a stator groove 11 and / or a stator heat dissipation channel 12 for heat dissipation. The rotor assembly 20 is disposed inside the stator assembly 10 and has a rotor groove 21 and / or a rotor heat dissipation channel 22 for heat dissipation. The front end cover 30 and the rear end cover 40 are respectively detachably disposed at both ends of the stator assembly 10.

[0037] In this embodiment, by directly exposing the stator assembly 10 to the air without a housing, the overall structure is simplified, reducing manufacturing costs and assembly difficulty. This also facilitates later cleaning and maintenance. Grooves and heat dissipation channels are provided on the stator assembly 10 and rotor assembly 20, allowing the motor to directly dissipate heat into the air during operation, enhancing the heat dissipation effect of the stator assembly 10 and rotor assembly 20. This avoids the problems of structural complexity, high cost, and maintenance difficulties associated with existing oil-cooled motors. Furthermore, both the front cover 30 and the rear cover 40 are detachably mounted at both ends of the stator assembly 10, ensuring stable support, sealing, and protection of the motor. This also allows for easy disassembly and assembly when repairs or component replacement are needed, improving the motor's maintainability.

[0038] like Figure 2As shown, the stator assembly 10 includes a stator core 13 and a stator winding 14 wound on the stator core 13. Multiple stator grooves 11 are circumferentially formed on the outer surface of the stator core 13, which increases the surface area of ​​the stator core 13. This allows for more thorough contact with the outside air during motor operation, improving the heat dissipation efficiency of the stator assembly 10 and preventing insulation aging or stator winding 14 burnout due to localized overheating. This enhances the overall operational reliability and service life of the motor. Furthermore, the stator assembly 10 in this application does not require additional cooling oil circuits or complex heat dissipation devices; natural air cooling is achieved through the structure of the outer surface of the stator core 13. This results in a simple structure, low manufacturing cost, and convenient maintenance.

[0039] like Figure 2 The stator assembly 10 includes a stator core 13 and a stator winding 14 wound on the stator core 13. The stator core 13 has a plurality of stator through holes 15 axially penetrating the stator core 13. The plurality of stator through holes 15 are distributed along the circumference of the stator core 13, and each stator through hole 15 forms a stator heat dissipation channel 12.

[0040] In this embodiment, multiple stator heat dissipation channels 12 that axially penetrate the stator core 13 are provided inside the stator core 13, so that an air circulation path can be formed inside the stator core 13 during motor operation, thereby achieving heat dissipation from the inside out and avoiding heat accumulation inside the stator core 13. Compared with the method of relying solely on the outer surface of the stator core 13 for heat dissipation, it can utilize both the inside and outside of the stator core 13 for heat dissipation at the same time, thus improving the overall heat dissipation efficiency.

[0041] like Figure 3 As shown, the rotor assembly 20 includes a rotor core 23 and a rotor shaft 24 disposed inside the rotor core 23. Multiple rotor grooves 21 are circumferentially formed on the outer surface of the rotor core 23, increasing its surface area and allowing for more thorough contact with the outside air during motor operation. This facilitates heat dissipation from the rotor grooves 21 into the air, improving the heat dissipation efficiency of the stator assembly 10 and enhancing the overall operational reliability and service life of the motor. Furthermore, the rotor assembly 20 in this application does not require additional cooling oil circuits or complex heat dissipation devices; natural air cooling is achieved through the structure of the outer surface of the rotor core 23, resulting in a simple structure, low manufacturing cost, and convenient maintenance. In addition, the rotor grooves 21 reduce the surface temperature of the rotor assembly 20 while preventing demagnetization and insulation damage to the rotor core 23 caused by heat accumulation.

[0042] like Figure 3As shown, the rotor assembly 20 includes a rotor core 23 and a rotor shaft 24 disposed inside the rotor core 23. The rotor core 23 has a plurality of rotor through holes 25 that axially penetrate the rotor core 23. The plurality of rotor through holes 25 are distributed along the circumference of the rotor core 23, and each rotor through hole 25 forms a rotor heat dissipation channel 22.

[0043] In this embodiment, multiple axially penetrating rotor heat dissipation channels 22 are provided inside the rotor core 23, so that an airflow path can be formed inside the rotor core 23 during motor operation, thereby achieving heat dissipation from the inside out and avoiding heat accumulation inside the rotor core 23. Compared with the method of relying solely on the outer surface of the rotor core 23 for heat dissipation, it can utilize both the inside and outside of the rotor core 23 for heat dissipation, thereby improving the overall heat dissipation efficiency.

[0044] like Figure 3 As shown, the rotor assembly 20 includes a rotor core 23 and a rotor shaft 24 disposed inside the rotor core 23. The rotor assembly 20 also includes a rotor baffle 26 and a plurality of blades 27. The rotor baffle 26 is annular and is sleeved on the part of the rotor shaft 24 that protrudes from the rotor core 23 and is connected to the rotor core 23. The plurality of blades 27 are disposed in the circumference of the rotor baffle 26.

[0045] In this embodiment, the combined use of rotor baffle 26 and blades 27 enables rotor assembly 20 to not only possess its original electromagnetic function but also its aerodynamic function. During the rotation of rotor assembly 20, the airflow speed inside the motor is accelerated. This enhances air convection in the gap area between stator assembly 10 and rotor assembly 20, and also accelerates airflow in heat dissipation structures such as stator groove 11, stator heat dissipation channel 12, rotor groove 21, and rotor heat dissipation channel 22, thereby improving overall heat dissipation efficiency and reducing motor temperature rise. Furthermore, the annular structure of rotor baffle 26 ensures stable support and balanced force on blades 27, preventing structural deformation or vibration caused by high-speed rotation, thus improving the stability and reliability of motor operation.

[0046] like Figure 5 As shown, the rear end cover 40 includes a connecting structure 41 and a heat dissipation structure 42. The connecting structure 41 is detachably connected to one end of the stator assembly 10. The heat dissipation structure 42 is connected to the connecting structure 41. The heat dissipation structure 42 covers the end of the rotor assembly 20 and at least dissipates heat from the rotor assembly 20.

[0047] In this embodiment, the heat dissipation structure 42 covers the end of the rotor assembly 20, allowing the end of the rotor assembly 20 to exchange heat fully with the outside air. This prevents localized overheating caused by heat accumulation at the end of the rotor assembly 20 during high-speed operation, effectively reducing the risk of motor temperature rise and ensuring stable operation of the motor under high load conditions. Furthermore, the rear end cover 40 is detachably connected to the stator assembly 10 via the connecting structure 41, which not only makes motor assembly and maintenance more convenient but also allows for quick disassembly and installation when cleaning, repair, or replacement of parts is required, improving motor maintenance efficiency.

[0048] like Figure 5 As shown, the connection structure 41 includes an annular plate 411 and a plurality of fasteners. The annular plate 411 has a plurality of connection holes 412 in its circumferential direction. The stator assembly 10 has a plurality of threaded holes in its circumferential direction at one end facing the rear end cover 40. Each fastener passes through a connection hole 412 and is threadedly connected to a threaded hole. The heat dissipation structure 42 includes an annular wall 421 and a heat dissipation plate 422. One end of the annular wall 421 is connected to the annular plate 411, and the other end of the annular wall 421 is connected to the heat dissipation plate 422. The heat dissipation plate 422 has a plurality of heat dissipation holes 4221.

[0049] In this embodiment, the heat dissipation structure 42 can be installed over the end of the rotor assembly 20, and the heat transferred from the rotor assembly 20 to the rear end cover 40 through the heat dissipation holes 4221 is discharged, thereby achieving air heat exchange and improving the heat dissipation efficiency of the motor end, avoiding overheating of the end due to poor local air circulation. Moreover, the covering structure formed by the annular wall 421 and the heat dissipation plate 422 not only protects the end of the rotor assembly 20 from external impurities and dust, but also achieves a combination of forced air convection and natural heat dissipation, thus combining protection and heat dissipation.

[0050] like Figure 4 As shown, the front end cover 30 includes a first annular member 31, a second annular member 32, a plurality of first bolts, and a plurality of second bolts. The first annular member 31 is used to connect with the compressor head of the air compressor, and the second annular member 32 is connected with the stator assembly 10. The outer diameter of the first annular member 31 is larger than the outer diameter of the second annular member 32. The first annular member 31 and the second annular member 32 are fixedly connected. The first annular member 31 has a plurality of compressor head fixing holes 311 in the circumferential direction, and the second annular member 32 has a plurality of stator fixing holes 321 in the circumferential direction. The first bolts pass through the compressor head fixing holes 311 and are connected to the compressor head, and the second bolts pass through the stator fixing holes 321 and are connected to the stator assembly 10.

[0051] In this embodiment, the front cover 30 adopts a double-ring structure. The first ring 31 is connected to the compressor head, and the second ring 32 is connected to and fixed to the stator assembly 10. This makes the stress distribution of the front cover 30 more uniform, avoiding deformation or damage caused by local stress concentration. It also facilitates disassembly and maintenance, improving the convenience of motor installation and maintenance. Furthermore, the front cover 30 also has a bearing to connect the rotor shaft 24 to the air compressor head, while ensuring the stable installation of the stator assembly 10. This provides good support and precise alignment during motor operation, preventing malfunctions caused by vibration or misalignment, improving the overall stability and reliability of the motor, and simplifying the motor structure.

[0052] like Figure 6 As shown, the arrow in the stator groove 11 indicates the first heat dissipation path, which can directly discharge the heat generated in the stator assembly 10 into the air, thereby dissipating heat from the stator assembly 10.

[0053] like Figure 7 As shown, the arrow in the stator heat dissipation channel 12 indicates the second heat dissipation path, which can first dissipate the heat generated in the stator assembly 10 to the rear end cover 40, and then dissipate it into the air through the heat dissipation structure 42 of the rear end cover, thereby playing a role in heat dissipation of the stator assembly 10.

[0054] like Figure 8 As shown, the arrow in the rotor groove 21 indicates the third heat dissipation path, which can first dissipate the heat generated in the rotor assembly 20 to the rear end cover 40, and then dissipate it into the air through the heat dissipation structure 42 of the rear end cover, thus playing a role in heat dissipation of the rotor assembly 20.

[0055] like Figure 9 As shown, the arrow in the rotor heat dissipation channel 22 indicates the fourth heat dissipation path, which can first exhaust the heat generated in the rotor assembly 20 into the rear end cover 40, and then exhaust it into the air through the heat dissipation structure 42 of the rear end cover, thereby playing a role in heat dissipation of the rotor assembly 20.

[0056] An embodiment of this utility model also provides an air compressor, which includes a compressor head and the aforementioned casing-less motor. The compressor head and the front end cover 30 of the casing-less motor are connected, which reduces the complex installation structure between the traditional motor housing and the compressor head. The casing-less motor can be directly and reliably fixed to the compressor head, realizing the efficient transmission of motor output power, thereby ensuring the overall stability and reliability of the air compressor operation. It also simplifies the overall structure of the air compressor, improves assembly efficiency, and reduces manufacturing costs and maintenance difficulty.

[0057] The above description is merely an optional embodiment of this solution and is not intended to limit the solution. Various modifications and variations can be made to this solution by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this solution should be included within the scope of protection of this solution.

[0058] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0059] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as exemplary only and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0060] In the description of this solution, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the attached drawings. It is only for the convenience of describing this solution and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this solution. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0061] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0062] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this solution.

Claims

1. A shell-less electric machine characterized by, The device includes a stator assembly (10), a rotor assembly (20), a front end cover (30), and a rear end cover (40). The stator assembly (10) is exposed to the air and has a stator groove (11) and / or a stator heat dissipation channel (12) for heat dissipation. The rotor assembly (20) is disposed inside the stator assembly (10) and has a rotor groove (21) and / or a rotor heat dissipation channel (22) for heat dissipation. The front end cover (30) and the rear end cover (40) are detachably disposed at both ends of the stator assembly (10).

2. The casing-less motor according to claim 1, characterized in that, The stator assembly (10) includes a stator core (13) and a stator winding (14) wound on the stator core (13). The outer surface of the stator core (13) is provided with a plurality of stator grooves (11) in the circumferential direction.

3. The shell-less electric machine of claim 1, wherein, The stator assembly (10) includes a stator core (13) and a stator winding (14) wound on the stator core (13). The stator core (13) has a plurality of stator through holes (15) that axially penetrate the stator core (13). The plurality of stator through holes (15) are distributed along the circumference of the stator core (13), and each stator through hole (15) forms a stator heat dissipation channel (12).

4. The casingless motor according to claim 1, characterized in that, The rotor assembly (20) includes a rotor core (23) and a rotor shaft (24) disposed inside the rotor core (23). The outer surface of the rotor core (23) is provided with a plurality of rotor grooves (21) in the circumferential direction.

5. The casing-less motor according to claim 1, characterized in that, The rotor assembly (20) includes a rotor core (23) and a rotor shaft (24) disposed inside the rotor core (23). The rotor core (23) has a plurality of rotor through holes (25) that axially penetrate the rotor core (23). The plurality of rotor through holes (25) are distributed along the circumference of the rotor core (23), and each rotor through hole (25) forms a rotor heat dissipation channel (22).

6. The casing-less motor according to claim 1, characterized in that, The rotor assembly (20) includes a rotor core (23) and a rotor shaft (24) disposed inside the rotor core (23). The rotor assembly (20) also includes a rotor baffle (26) and a plurality of blades (27). The rotor baffle (26) is annular. The rotor baffle (26) is sleeved on the part of the rotor shaft (24) that protrudes from the rotor core (23) and is connected to the rotor core (23). The plurality of blades (27) are disposed in the circumference of the rotor baffle (26).

7. The casing-less motor according to claim 1, characterized in that, The rear end cover (40) includes a connecting structure (41) and a heat dissipation structure (42). The connecting structure (41) is detachably connected to one end of the stator assembly (10). The heat dissipation structure (42) is connected to the connecting structure (41). The heat dissipation structure (42) covers the end of the rotor assembly (20) and the heat dissipation structure (42) at least dissipates heat from the rotor assembly (20).

8. The shell-less electric machine of claim 7, wherein, The connection structure (41) includes an annular plate (411) and a plurality of fasteners. The annular plate (411) has a plurality of connection holes (412) in the circumferential direction. The stator assembly (10) has a plurality of threaded holes in the circumferential direction at one end facing the rear end cover (40). Each fastener passes through one of the connection holes (412) and is threadedly connected to one of the threaded holes. The heat dissipation structure (42) includes an annular wall (421) and a heat dissipation plate (422). One end of the annular wall (421) is connected to the annular plate (411), and the other end of the annular wall (421) is connected to the heat dissipation plate (422). The heat dissipation plate (422) has a plurality of heat dissipation holes (4221).

9. The shell-less electric machine of claim 1, wherein, The front end cover (30) includes a first annular component (31), a second annular component (32), a plurality of first bolts and a plurality of second bolts. The first annular component (31) is used to connect with the compressor head of the air compressor. The second annular component (32) is connected with the stator assembly (10). The outer diameter of the first annular component (31) is larger than the outer diameter of the second annular component (32). The first annular component (31) and the second annular component (32) are fixedly connected. The first annular component (31) has a plurality of compressor head fixing holes (311) in the circumferential direction. The second annular component (32) has a plurality of stator fixing holes (321) in the circumferential direction. The first bolts pass through the compressor head fixing holes (311) and are connected to the compressor head. The second bolts pass through the stator fixing holes (321) and are connected to the stator assembly (10).

10. An air compressor characterized by comprising: The air compressor includes a compressor head and a casing-less motor as described in any one of claims 1 to 9, wherein the compressor head and the front end cover (30) of the casing-less motor are connected.

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