Sealing device for air compressor and air compressor

Abstract

The embodiment of the utility model provides a sealing device for an air compressor and the air compressor. The air compressor at least comprises an impeller back plate and a rotating shaft. The impeller back plate is provided with an axial hole suitable for the rotating shaft to extend and pass in the axial direction. The sealing device may include: a sleeve disposed within the axial bore in a manner of fitting the axial bore, the sleeve having a hardness higher than that of the impeller back plate; the sealing ring is arranged between the sleeve and the rotating shaft and is fixed on the rotating shaft; the clamping ring is arranged between the sealing ring and the sleeve through radial acting force, and a sealing gap is formed between the clamping ring and the sealing ring and used for limiting gas leakage in the axial direction from the impeller back plate.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of air compressors, and in particular, to a sealing device for an air compressor and an air compressor. BACKGROUND

[0002] An air compressor (AC) can refer to a device that converts mechanical energy of a prime mover into gas pressure energy. An electric air compressor (EAC) is a kind of air compressor that uses an electric motor as a prime mover. Due to the advantages of high energy conversion efficiency, etc., the electric air compressor has been widely used in various fields, such as fuel cell systems.

[0003] The electric air compressor usually includes an impeller and an electric motor. The impeller can be fixed to the rotating shaft of the electric motor, so as to rotate at a high speed together with the rotating shaft. The gas can be supplied to the impeller, so that a high-pressure area is usually formed on the side of the impeller, while the side of the electric motor (e.g., the chamber where the electric motor is located) usually belongs to a low-pressure area. In addition, there can be a certain assembly gap between components such as the impeller and the rotating shaft, so that gas leakage from the high-pressure area along the assembly gap towards the low-pressure area can occur, thereby affecting the performance of the electric air compressor. SUMMARY

[0004] In view of the need for improvement of the prior art, embodiments of the present disclosure provide a sealing device for an air compressor and an air compressor.

[0005] In one aspect, embodiments of the present disclosure provide a sealing device for an air compressor. The air compressor at least includes an impeller back plate having an axial hole adapted for a rotating shaft to extend through in an axial direction, and the rotating shaft. The sealing device includes: a sleeve arranged in the axial hole in a manner of fitting with the axial hole, wherein a hardness of the sleeve is higher than a hardness of the impeller back plate; a sealing ring arranged between the sleeve and the rotating shaft and fixed on the rotating shaft; and a snap ring arranged between the sealing ring and the sleeve by a radial force, wherein a sealing gap is formed between the snap ring and the sealing ring for limiting gas leakage from the impeller back plate in the axial direction.

[0006] In one implementation, the sleeve is constructed by using a steel material, and the impeller back plate is constructed by using an aluminum alloy material or a plastic material.

[0007] [ In one implementation, the sleeve is assembled into the axial hole by a press-fit process, a hot-fit process, or a casting process.

[0008] In one implementation, the sleeve is configured to be flush with the axial hole in an axial direction.

[0009] In one implementation, the sleeve has a chamfer at an axial end of the sleeve to allow the sleeve to fit over the snap ring and the seal ring.

[0010] In one implementation, the snap ring is configured as a C-shaped elastic ring to allow the snap ring to be pressed against the sleeve by a radial clamping force.

[0011] In one implementation, the snap ring is fitted in a groove on an outer circumferential surface of the seal ring, wherein an axial width of the groove is greater than an axial width of the snap ring to form the seal gap between the snap ring and the seal ring.

[0012] In one implementation, the sleeve has a thickness in a range of 1 mm to 2 mm.

[0013] In another aspect, embodiments of the disclosure provide an air compressor, including: a rotation shaft; an impeller back plate having an axial hole adapted for the rotation shaft to extend therethrough in an axial direction; and the above-described sealing device.

[0014] In one implementation, the impeller back plate and the rotation shaft are connected to an impeller for gas compression, or the impeller back plate and the rotation shaft are connected to an impeller for use as a turbine. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and other objects, features and advantages of embodiments of the disclosure will become more apparent from the following more detailed description when taken in conjunction with the accompanying drawings, in which like reference characters refer to like elements throughout the different views. Also, the components in each of the figures can not be necessarily drawn to scale for the sake of depiction clarity.

[0016] Figure 1 A schematic cross-sectional view of an exemplary air compressor according to embodiments of the disclosure is shown.

[0017] Figure 2 A schematic cross-sectional view of a sealing device according to some embodiments is shown.

[0018] Figure 3 A partial enlarged view of a portion of Figure 2 is shown.

[0019] Figure 4 A schematic view of an exemplary seal ring according to some embodiments is shown.

[0020] Figure 5A diagram showing an exemplary snap ring is shown.

[0021] Figure 6 A diagram showing an exemplary snap ring and seal ring after being assembled together is shown.

[0022] Figure 7 A diagram showing an exemplary seal device and impeller back plate after being assembled together is shown.

[0023] List of Reference Signs

[0024] 100 air compressor

[0025] 110 casing

[0026] 120 motor

[0027] 121 rotor

[0028] 122 stator

[0029] 123 rotating shaft

[0030] 131 first bearing

[0031] 132 second bearing

[0032] 141 first volute

[0033] 142 first impeller

[0034] 143 first impeller back plate

[0035] 151 second volute

[0036] 152 second impeller

[0037] 153 second impeller back plate

[0038] 160 first seal device

[0039] 170 second seal device

[0040] 161 sleeve

[0041] 162 seal ring

[0042] 163 snap ring

[0043] 162a groove

[0044] 163a opening DETAILED DESCRIPTION

[0045] The subject matter described herein will now be discussed with reference to various embodiments. It is to be understood that the discussion of these embodiments is merely provided for the purposes of enabling those with ordinary skill in the art to better understand and implement the subject matter described herein, and is not provided to limit the scope, applicability, or examples set forth in the claims. Alterations and modifications to the function and arrangement of elements can be made without departing from the scope of the claims. Various embodiments can omit, substitute, or add various procedures or components as appropriate.

[0046] In an electric air compressor, to ensure the functional efficiency of the impeller, the impeller backside clearance needs to be small enough, and the impeller backplate can provide the clearance structure support for the impeller. The impeller backplate can have an axial hole through which the rotating shaft of the electric motor can extend in the axial direction. The impeller can be fixed to one end of the rotating shaft extending through the axial hole, so that the impeller can rotate together with the rotating shaft. Depending on the type of the electric air compressor, the impeller can be configured to achieve different purposes. For example, the impeller can act as a gas compression assembly, or as a turbine assembly.

[0047] As an example, in a two-stage compressor, corresponding impellers are fixed at both ends of the rotating shaft of the electric motor, so that two-stage compression of gas (e.g., air) can be achieved. Thus, the impeller side at either end will generate compressed gas, forming a high-pressure area. In contrast, the electric motor side (e.g., the chamber where the electric motor is located) belongs to a low-pressure area. If the compressed gas leaks from the high-pressure area to the low-pressure area, it can cause problems such as insufficient pressure or supply of compressed gas, thereby affecting the working efficiency and performance of the electric air compressor.

[0048] As another example, in a turbocharged compressor, corresponding impellers are fixed at both ends of the rotating shaft of the electric motor, where the impeller at one end can act as a gas compression assembly, and the impeller at the other end can act as a turbine assembly. The impeller side acting as the gas compression assembly can compress gas (e.g., air) to generate compressed gas. The impeller acting as the turbine assembly can be driven by high-pressure exhaust gas from other equipment to provide auxiliary power for the impeller as the compression assembly. Regardless of whether it acts as a compression assembly or a turbine assembly, the impeller side will form a high-pressure area. In contrast, the electric motor side belongs to a low-pressure area. If the compressed gas leaks from the high-pressure area to the low-pressure area, it can cause problems such as insufficient pressure or supply of compressed air; and if the high-pressure exhaust gas leaks from the high-pressure area to the low-pressure area, it can affect the reliable operation of the electric motor, especially when the high-pressure exhaust gas contains water vapor, which can damage components such as the electric motor. It can be seen that in either case, gas leakage will affect the working efficiency and performance of the electric air compressor.

[0049] Therefore, embodiments of this disclosure provide sealing devices for air compressors and corresponding air compressors. Embodiments of this disclosure are applicable to various types of air compressors, such as two-stage compressors, turbocharged compressors, or other types of air compressors that may experience gas leakage problems as described above. Various embodiments of this disclosure will now be described in detail.

[0050] In this article, "axial" can refer to the axial direction of the air compressor's shaft, and "radial" can refer to the direction perpendicular to the axial direction of the shaft. The axial direction can be represented by X, and the radial direction by Y.

[0051] Figure 1 A schematic cross-sectional view of an exemplary air compressor according to an embodiment of the present disclosure is shown.

[0052] exist Figure 1 In the example, air compressor 100 may include a housing 110. Housing 110 may define an internal cavity of air compressor 100. Electric motor 120 may be disposed within the internal cavity. Electric motor 120 may include a rotor 121, a stator 122, and a shaft 123. Rotor 121 may be fixedly connected to shaft 123. Stator 122 may be disposed radially outward of rotor 121. Shaft 123 may be rotatably supported within housing 110 by first bearing 131 and second bearing 132. Shaft 123 may extend laterally along the axial direction X into first volute 141 and second volute 151, respectively. First impeller 142 may be disposed within first volute 141 and fixed to shaft 123. Second impeller 152 may be disposed within second volute 151 and fixed to shaft 123. First impeller 142 and second impeller may be fixed to shaft 123 by various suitable connection methods, such as bolts. Therefore, when the shaft 123 rotates with the rotor 121, the first impeller 142 and the second impeller 152 will rotate together. Furthermore, the first impeller 142 can be connected to a first impeller back plate 143, which provides structural support for the first impeller 142. The first impeller back plate 143 is typically constructed in a disk shape, with an axial hole at its center suitable for the shaft 123 to pass through in the axial direction X. Similarly, the second impeller 152 can be connected to a second impeller back plate 153, which provides structural support for the second impeller 152. The second impeller back plate 153 is typically constructed in a disk shape, with an axial hole at its center suitable for the shaft 123 to pass through in the axial direction X.

[0053] It should be understood that only some structures that may be related to embodiments of this disclosure have been described above. In addition to the structures described above, the air compressor 100 may also include various other structures for realizing its function, which will not be described in detail here.

[0054] In one implementation, the air compressor 100 can be implemented as a two-stage compressor. In this implementation, the first impeller 142 and the second impeller 152 can be used to achieve gas compression. For example, gas from the outside (e.g., air) can be supplied to the first impeller 142 and compressed by the high-speed rotation of the first impeller 142, thereby generating a first compressed gas. The first compressed gas is transmitted via a gas passage (in...) Figure 1 (Not shown in the image) reaches the second impeller 152, and is further compressed by the high-speed rotation of the second impeller 152, thereby generating a second compressed gas. The second compressed gas can be discharged through the outlet of the air compressor 100 (in... Figure 1 (Not shown in the image) Output, for example, to be used as a gas source for downstream equipment.

[0055] In one implementation, the air compressor 100 can be implemented as a turbocharged compressor. In this implementation, one of the first impeller 142 and the second impeller 152 can act as a gas compression assembly, while the other can act as a turbine assembly. Assuming the first impeller 142 acts as the gas compression assembly and the second impeller 152 acts as the turbine assembly, high-pressure exhaust gas from other equipment can be supplied to the second impeller 152, thereby driving the second impeller 152 to rotate. The first impeller 142 can rotate at high speed under the drive of the electric motor 120 and / or the second impeller 152, compressing the gas supplied to the first impeller 142 to produce compressed gas. The compressed gas can be output via the outlet of the air compressor 100. As an example, the air compressor 100 can be applied to a fuel cell system, in which case the compressed gas can be supplied to the fuel cell, and the aforementioned high-pressure exhaust gas can be generated after the compressed gas reacts in the fuel cell.

[0056] Regardless of the implementation method, high-pressure areas will be formed on the back side of the first impeller 142 (i.e., at the first impeller back plate 143) and the back side of the second impeller 152 (i.e., at the second impeller back plate 153). In contrast, the side of the motor 120 is a low-pressure area. Furthermore, there may typically be a certain assembly gap between the two impellers, the impeller back plates, and the shaft 123. Therefore, gas leakage may occur from the high-pressure area along such assembly gaps to the low-pressure area. Whether it is compressed gas or high-pressure exhaust gas leakage, it will affect the operating efficiency and performance of the air compressor 100, and may even damage the motor 120.

[0057] Therefore, the air compressor 100 may further include a first sealing device 160 and a second sealing device 170. The first sealing device 160 may be disposed between the first impeller back plate 143 and the shaft 123 to limit gas leakage from the first impeller 142 side to the motor 120 side. The second sealing device 170 may be disposed between the second impeller back plate 153 and the shaft 123 to limit gas leakage from the second impeller 152 side to the motor 120 side.

[0058] As can be seen, such a sealing device can effectively limit potential gas leakage, thereby significantly improving the operating efficiency and performance of the air compressor. Furthermore, it can prevent damage to components (such as the electric motor) caused by gas leakage, thus ensuring the operational reliability of the air compressor.

[0059] It should be understood that the embodiments of this disclosure can also be applied to air compressors with other structures, and are not limited to them. Figure 1 The structure of the air compressor 100 is shown in the figure. For example, in different implementations, the air compressor may include other numbers of impellers, such as one impeller or more than two impellers. Accordingly, one or more sealing devices may be provided.

[0060] The first sealing device 160 and the second sealing device 170 can have similar structures. The following description will use the first sealing device 160 and the first impeller back plate 143 as examples. However, it should be understood that the embodiments described below regarding the first sealing device 160 and the first impeller back plate 143 are also applicable to the second sealing device 170 and the second impeller back plate 153. Therefore, for the sake of brevity, the second sealing device 170 and the second impeller back plate 153 will not be described again.

[0061] Figure 2 A schematic cross-sectional view of a sealing device according to some embodiments is shown.

[0062] like Figure 2 As shown, the first sealing device 160 can be arranged between the first impeller back plate 143 and the shaft 123. For example, the shaft 123 can have a stepped portion or a groove on its outer peripheral surface facing the first impeller back plate 143 for mounting the first sealing device 160.

[0063] The first sealing device 160 may include a sleeve 161. The sleeve 161 may be disposed between the first impeller back plate 143 and the rotating shaft 123. For example, the sleeve 161 may be disposed within the axial hole of the first impeller back plate 143 in such a way that it fits against the axial hole of the first impeller back plate 143. In this way, when the rotating shaft 123 rotates, the sleeve 161 may be considered not to rotate relative to the rotating shaft 123.

[0064] The first sealing device 160 may further include a sealing ring 162. The sealing ring 162 may be disposed between the sleeve 161 and the rotating shaft 123. For example, the sealing ring 162 may be fixed to the rotating shaft 123. As an example, the sealing ring 162 may be fixed to the rotating shaft 123 by various suitable methods such as bolts or press-fitting. Therefore, the sealing ring 162 may rotate together with the rotating shaft 123. The sealing ring 162 may be constructed using, for example, a metallic material.

[0065] The first sealing device 160 may further include a retaining ring 163. The retaining ring 163 may be disposed between the sealing ring 162 and the sleeve 161. In one implementation, the retaining ring 163 may be disposed between the sealing ring 162 and the sleeve 161 by a radial force. For example, the radial force may be a force acting in the radial direction Y. Thus, when the sealing ring 162 rotates together with the shaft 123, the retaining ring 163 may be considered not to rotate relative to the sealing ring 162. The retaining ring 163 may be constructed, for example, using a metallic material.

[0066] As described above, when the shaft 123 rotates, the sealing ring 162 rotates together with the shaft 123, while the retaining ring 163 remains relatively stationary. Therefore, the sealing ring 162 can be considered a moving ring, and the retaining ring 163 can be considered a stationary ring. In this way, the sealing ring 162 and the retaining ring 163 can work together to achieve a dynamic seal. For example, a sealing gap can be formed between the sealing ring 162 and the retaining ring 163, which can effectively limit gas leakage from the first impeller back plate 143 to the motor 120 side.

[0067] When the shaft 123 rotates, the high rotational speed can cause vibrations. Additionally, since the gas pressure on the side of the first impeller back plate 143 is greater than that on the side of the motor 120, a gas thrust may be generated from the high-pressure side to the low-pressure side. Under the influence of vibration and / or gas thrust, the sealing ring 162 may experience some displacement in the axial direction X, i.e., axial displacement. This axial displacement may cause the sealing ring 162 to come into contact with the retaining ring 163. Assuming the retaining ring 163 remains completely stationary when in contact with the sealing ring 162, wear will occur between the retaining ring 163 and the sealing ring 162, which can cause several problems. For example, such wear may affect the sealing effect between the sealing ring 162 and the retaining ring 163, may cause the sealing ring 162 and the retaining ring 163 to stick together and completely lose their sealing effect, may generate debris (such as metal shavings) that could damage other components in the air compressor, and so on. Based on this consideration, in the embodiments of this disclosure, the retaining ring 163 can be arranged between the sealing ring 162 and the sleeve 161 by a radial force. Therefore, when the sealing ring 162 and the retaining ring 163 come into contact, the retaining ring 163 can move in the axial direction X with the axial displacement of the sealing ring 162 (e.g., producing a small axial displacement), thereby effectively reducing or avoiding wear problems when the sealing ring 162 and the retaining ring 163 come into contact.

[0068] Furthermore, suppose that instead of sleeve 161, retaining ring 163 is directly positioned between the first impeller back plate 143 and sealing ring 162 by radial force (e.g., retaining ring 163 is positioned within the axial hole of the first impeller back plate 143 by radial force). Then, when retaining ring 163 undergoes axial displacement, it will experience axial friction with the first impeller back plate 143. As this axial friction reaches a certain level, it may cause grooves to be worn into the first impeller back plate 143 (because impeller back plates are typically constructed using materials with lower hardness due to cost and weight considerations). If retaining ring 163 is confined within these grooves, its axial displacement will be restricted. Once the axial displacement of retaining ring 163 is restricted, the aforementioned wear problem will again occur between sealing ring 162 and retaining ring 163. To address this situation, it is assumed that a high-hardness material is used to construct the impeller back plate. While this method addresses the wear problem of the impeller back plate to some extent, the impeller back plate is typically quite large, and high-hardness materials are generally heavy and expensive. Therefore, this method may significantly increase the weight and cost of the impeller back plate, consequently leading to a significant increase in the weight and cost of the air compressor. Based on this consideration, in the embodiments of this disclosure, the sleeve 161 can be fitted into the axial hole of the first impeller back plate 143, and the hardness of the sleeve 161 is higher than that of the first impeller back plate 143. Thus, although the retaining ring 163 rubs against the sleeve 161 during axial displacement, the high hardness of the sleeve 161 effectively prevents wear, thereby mitigating or avoiding the problem of restricted axial displacement of the retaining ring 163, and further mitigating or avoiding wear between the sealing ring 162 and the retaining ring 163. Therefore, the working efficiency and performance of the air compressor 100 can be effectively improved. Furthermore, since the sleeve 161 is much smaller than the impeller back plate, it does not lead to a significant increase in the weight and cost of the air compressor.

[0069] In one implementation, the sleeve 161 can be constructed using steel, while the first impeller back plate 143 can be constructed using aluminum alloy or plastic. This allows the sleeve 161 to have a higher hardness than the first impeller back plate 143, thereby reducing or avoiding the aforementioned wear problems. Furthermore, using aluminum alloy or plastic to construct the first impeller back plate 143 effectively avoids increasing the weight and cost of the air compressor.

[0070] The sleeve 161 can be arranged in the axial hole of the first impeller back plate 143 using various applicable processes. For example, the sleeve 161 can be assembled into the axial hole of the first impeller back plate 143 by press fitting, hot fitting, casting, etc. In this way, the assembly between the sleeve and the impeller back plate can be achieved simply and efficiently.

[0071] In one implementation, the sleeve 161 may be constructed flush with the axial bore of the first impeller back plate 143 in the axial direction. For example, the axial width of the sleeve 161 may be the same as the axial width of the axial bore of the first impeller back plate 143. In this document, the axial width may refer to the width along the axial direction X. With this construction, even if the retaining ring 163 undergoes a large axial displacement, it will not directly contact the first impeller back plate 143, thereby preventing wear on the first impeller back plate 143. Furthermore, this construction also prevents interference between the sleeve 161 and other components near the first impeller back plate 143.

[0072] The thickness of sleeve 161 can be set according to factors such as the actual application scenario. For example, considering that the wear between the retaining ring 163 and the sealing ring 162 may be less than 1 mm, the thickness of sleeve 161 can be set between 1 mm and 2 mm.

[0073] In one implementation, the sleeve 161 may have a chamfer or bevel at its axial end, allowing it to be easily assembled onto the sealing ring 162 and the retaining ring 163. For example, the sleeve 161 may be assembled into the axial hole of the first impeller back plate 143, and the retaining ring 163 may be assembled onto the sealing ring 162. Then, the first impeller back plate 143 with the sleeve 161 may be press-fitted together with the sealing ring 162 and the retaining ring 163 by a press-fit process.

[0074] In one implementation, the sealing ring 162 may have a groove on its outer circumferential surface. Accordingly, a retaining ring 163 may be fitted into this groove. The axial width of the groove may be greater than the axial width of the retaining ring 163, thereby forming a sealing gap between the retaining ring 163 and the sealing ring 162, thus limiting gas leakage.

[0075] For ease of understanding, Figure 3 It shows Figure 2 A magnified view of a portion of the structure. For clarity, in... Figure 3 Different shades are used to distinguish various structures. For example... Figure 3 As shown, the sealing ring 162 may have a groove 162a on its outer circumferential surface, and the retaining ring 163 may be fitted into the groove 162a. The axial width of the groove 162a may be greater than the axial width of the retaining ring 163. Therefore, a sealing gap G may be formed between the sealing ring 162 and the retaining ring 163. Through the sealing gap G, gas leakage from the side of the first impeller back plate 143 along the axial direction X to the side of the motor 120 can be effectively limited.

[0076] Figure 4 A schematic diagram of an exemplary sealing ring according to some embodiments is shown. Figure 4As shown, the sealing ring 162 may have an annular shape and a central hole. The sealing ring 162 can be fitted onto the rotating shaft 123 through its central hole. In addition, a groove 162a for arranging a retaining ring 163 is formed on the outer peripheral surface of the sealing ring 162.

[0077] In some implementations, the retaining ring 163 can be constructed as a C-shaped elastic ring, allowing it to abut against the sleeve 161 by radial clamping force. For example, the retaining ring 163 can be annular in shape but with an opening. With this construction, the retaining ring 163 can be easily fitted between the sealing ring 162 and the sleeve 161 by radial clamping force. Figure 5 A schematic diagram of an exemplary retaining ring according to some embodiments is shown. Figure 5 As shown, the retaining ring 163 can be constructed as a C-shaped elastic ring having an opening 163a.

[0078] Figure 6 A schematic diagram is shown showing the snap ring and sealing ring assembled together according to some embodiments. Figure 6 As shown, the retaining ring 163 can be easily fitted into the groove of the sealing ring 162 through its opening 163a and elastic force.

[0079] Figure 7 A schematic diagram is shown showing the sealing device and impeller backplate assembled together according to some embodiments. Figure 7 As shown, the first sealing device 160 can be arranged between the first impeller back plate 143 and the rotating shaft 123 (in Figure 7 (Not shown in the image) can also be understood as the first sealing device 160 being arranged within the axial hole of the first impeller back plate 143. The first sealing device 160 may include a sleeve 161, a sealing ring 162, and a retaining ring 163.

[0080] As can be seen, this arrangement offers various benefits. For example, the sealing device effectively limits gas leakage from the impeller back plate side to the motor side. Furthermore, because the sealing device includes a high-hardness sleeve, it avoids the problem of the retaining ring wearing off the impeller back plate during axial movement, thus effectively ensuring the sealing effect and improving the air compressor's efficiency and performance. Moreover, because the impeller back plate can be constructed from a lower-hardness material, it avoids increasing the weight and cost of the air compressor.

[0081] The optional embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present disclosure are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present disclosure, various modifications can be made to the technical solutions of the embodiments of the present disclosure, and these modifications all fall within the protection scope of the embodiments of the present disclosure.

Claims

1. A sealing device for an air compressor, the air compressor comprising at least an impeller back plate and a shaft, the impeller back plate having an axial hole adapted for the shaft to extend through in the axial direction, characterized in that, The sealing device includes: A sleeve (161) is arranged in the axial hole in a manner that fits against the axial hole, wherein the hardness of the sleeve (161) is higher than the hardness of the impeller back plate. A sealing ring (162) is disposed between the sleeve (161) and the rotating shaft and is fixed to the rotating shaft; and A retaining ring (163) is arranged between the sealing ring (162) and the sleeve (161) by a radial force, wherein a sealing gap is formed between the retaining ring (163) and the sealing ring (162) to limit gas leakage from the impeller back plate in the axial direction.

2. The sealing device for an air compressor according to claim 1, characterized in that, The sleeve (161) is constructed of steel, and the impeller back plate is constructed of aluminum alloy or plastic.

3. The sealing device for an air compressor according to claim 1, characterized in that, The sleeve (161) is assembled into the axial hole by press fitting, hot fitting or casting.

4. The sealing device for an air compressor according to claim 1, characterized in that, The sleeve (161) is constructed flush with the axial hole in the axial direction.

5. The sealing device for an air compressor according to claim 1, characterized in that, The sleeve (161) has a chamfer at its axial end so that the sleeve (161) is fitted onto the retaining ring (163) and the sealing ring (162).

6. The sealing device for an air compressor according to claim 1, characterized in that, The retaining ring (163) is constructed as a C-shaped elastic ring such that the retaining ring (163) abuts against the sleeve (161) by a radial clamping force.

7. The sealing device for an air compressor according to claim 1, characterized in that, The retaining ring (163) is fitted into a groove on the outer circumferential surface of the sealing ring (162), wherein the axial width of the groove is greater than the axial width of the retaining ring (163) so as to form the sealing gap between the retaining ring (163) and the sealing ring (162).

8. The sealing device for an air compressor according to claim 1, characterized in that, The thickness of the sleeve (161) is in the range of 1 mm to 2 mm.

9. An air compressor, characterized in that, include: Shaft; The impeller back plate has an axial hole through which the shaft extends in the axial direction; as well as A sealing device for an air compressor according to any one of claims 1 to 8.

10. The air compressor according to claim 9, characterized in that, The impeller back plate and the shaft are connected to the impeller for gas compression, or The impeller backplate and the shaft are connected to the impeller, which serves as a turbine.

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