Electric compressor

Abstract

The electric compressor includes: a motor housing that serves as the power source for the compressor unit; a rotor that rotates within the motor housing; a helical spring that applies force to the rotor along the axis of rotation; a bearing having an inner ring and an outer ring, the inner ring being sandwiched between the motor housing and the motor and held in place by the rotor, the outer ring being abutted against a portion of the motor housing by the force applied by the helical spring; and a limiter that prevents the rotor from displacing beyond a predetermined limit displacement against the force applied by the helical spring, and allows the rotor to displace beyond the limit displacement, wherein when the rotor displaces to the limit displacement, the deformed helical spring is at least the length of the contact height.

Description

Technical Field

[0001] This disclosure relates to electric compressors. Background Technology

[0002] Conventionally, in this field, the intensifier described in Patent Document 1 is known. In this intensifier, bearings are sandwiched between the rotor and the housing, and the rotor is supported by the bearings. Furthermore, the intensifier includes springs for applying pressure to these bearings axially.

[0003] Patent Document 1: Japanese Utility Model Application Publication No. 63-009428 Summary of the Invention

[0004] In such rotating machinery, where a bearing is sandwiched between a rotor and a housing, if the rotor displaces axially due to vibration, the inner ring on the rotor side and the outer ring on the housing side of the bearing may sometimes shift axially. Consequently, the bearing may disintegrate. In view of this problem, this disclosure describes an electric compressor that reduces the possibility of bearing disintegration caused by vibration.

[0005] One aspect of the electric compressor disclosed herein includes: a motor housing serving as a power source for the compressor unit; a rotor that rotates within the housing about a predetermined axis of rotation; a pressure spring that applies force to the rotor along the axis of rotation; a rolling bearing sandwiched between the housing and the motor, having: an inner ring held in place of the rotor; and an outer ring that abuts against a predetermined abutment portion of the housing along the axis of rotation by the force of the pressure spring; and a limiter that prevents the rotor from displacing beyond a predetermined limit displacement against the force of the pressure spring, and allows rotor displacement not exceeding the limit displacement, wherein when the rotor displaces to the limit displacement, the deformed pressure spring has a length exceeding the contact height.

[0006] The electric compressor according to this disclosure can reduce the possibility of bearing decomposition caused by vibration. Attached Figure Description

[0007] Figure 1 This is a schematic cross-sectional view of the electric compressor of this embodiment.

[0008] Figure 2 It means Figure 1 A cross-sectional view of an example near the bearing of an electric compressor.

[0009] Figure 3 It is a cross-sectional view showing the retainer, limiter, and helical spring under extreme displacement conditions.

[0010] Figure 4 (a) is a cross-sectional view showing the initial state, and (b) is a cross-sectional view showing the positional relationship of the rotor, bearings, etc. under the limit displacement state.

[0011] Figure 5 (a) to (c) are cross-sectional views showing modified examples of the limit switch. Detailed Implementation

[0012] One aspect of the electric compressor disclosed herein includes: a motor housing serving as a power source for the compressor unit; a rotor that rotates within the housing about a predetermined axis of rotation; a pressure spring that applies force to the rotor along the axis of rotation; a rolling bearing sandwiched between the housing and the motor, having: an inner ring held in place of the rotor; and an outer ring that abuts against a predetermined abutment portion of the housing along the axis of rotation by the force of the pressure spring; and a limiter that prevents the rotor from displacing beyond a predetermined limit displacement against the force of the pressure spring, and allows rotor displacement not exceeding the limit displacement, wherein when the rotor displaces to the limit displacement, the deformed pressure spring has a length exceeding the contact height.

[0013] Alternatively, in the electric compressor disclosed herein, the following formula can be satisfied when the length of the compression spring after deformation when the rotor is displaced to its limit displacement is set as L, the free length of the compression spring is set as L0, and the contact height of the compression spring is set as Lc:

[0014] 20%≤(L0-L) / (L0-Lc)≤80%.

[0015] Alternatively, the limiting displacement may be less than the minimum offset that would cause ball slippage when the inner and outer rings of the rolling bearing are offset relative to each other in the direction of the rotation axis. The rolling bearing may also be an angular contact ball bearing positioned in the direction of the thrust force supporting the pressure spring. Furthermore, in the electric compressor of this disclosure, the pressure spring, after deformation, may be in a state of maintaining elasticity and repulsion when the rotor displacement reaches its limiting displacement.

[0016] Alternatively, the limiter can be located within the housing, and the displaced rotor may interfere directly or indirectly with the limiter. Alternatively, the limiter can be a retaining ring embedded in a circumferentially extending groove on the inner circumferential surface of the housing. Furthermore, the limiter can also be located directly or indirectly on the rotor and move together with it, thus interfering with the housing.

[0017] Hereinafter, the electric compressor 1 according to the embodiments of the present disclosure will be described with reference to the accompanying drawings. Figure 1 This is a schematic cross-sectional view of the electric compressor 1 according to this embodiment. Furthermore, some features are exaggerated in the various figures, so the dimensional ratios of different parts may not be consistent across different figures.

[0018] The electric compressor 1 is, for example, mounted in vehicles, aircraft, etc. For instance, when the electric compressor 1 is mounted in a vehicle as part of a second-stage turbocharger, it is used to compress air in the pre-stage of a turbocharger (not shown) and supply the compressed air to the turbocharger. In the following description, when only "axial," "radial," and "circumferential" are mentioned, they refer to the axial, radial, and circumferential rotation of the impeller 3, which will be described later. Furthermore, when terms such as "front" and "rear" are used in the following description, they refer to the axial direction of the compressor section 2 (described later). Figure 1 The left side) is set as the front side, and the motor side 5 ( Figure 1 The right side is designated as the rear side.

[0019] The electric compressor 1 includes a compressor section 2 for compressing air. The compressor section 2 includes an impeller 3 that rotates about a rotation axis H, and an impeller housing 11 that houses the impeller 3. The electric compressor 1 also includes a motor 5 as the power source for the rotation of the impeller 3. Furthermore, the electric compressor 1 includes a housing 7 that houses the impeller 3 and the motor 5. The housing 7 includes the impeller housing 11 that houses the impeller 3, as described above, and a motor housing 13 that houses the motor 5. The impeller housing 11 and the motor housing 13 can each be composed of multiple components, and the components and their arrangement can be freely designed.

[0020] The impeller housing 11 and the motor housing 13 are connected along the rotation axis H. A rotor 15 extends from inside the impeller housing 11 into the motor housing 13 along the rotation axis H. An impeller 3 is provided at the front end of the rotor 15, and the rotor 15 is rotated by the driving force of the motor 5. The motor 5 consists of a coil 5a disposed in the motor housing 13 and a magnet 5b disposed in the rotor 15.

[0021] The impeller housing 11 has a diffuser 17 disposed opposite to the outer peripheral side of the outlet of the impeller 3. Additionally, the impeller housing 11 has a vortex member 19 disposed on the outer peripheral side of the diffuser 17. Furthermore, the impeller housing 11 has: an intake port 21 that opens outwards at a position axially opposite to the inlet of the impeller 3; and an outlet port 23, which is the outlet of the vortex member 19.

[0022] When electricity is supplied to the motor 5, the impeller 3 rotates within the impeller housing 11 due to the rotation of the rotor 15. Consequently, external air is drawn axially into the impeller 3 through the intake port 21 and discharged radially outward from the impeller outlet. The air from the impeller outlet flows into the diffuser 17, where it is compressed along with the vortex element 19. This compressed air is then supplied to the turbocharger (not shown) through the exhaust port 23.

[0023] Next, the bearing structure of the rotor 15 will be described. The electric compressor 1 has two bearings 27 and 29 (rolling bearings) that support the rotor 15. The bearings 27 and 29 are axially separated from the motor 5 and are sandwiched between the outer peripheral surface of the rotor 15 and the inner peripheral surface of the motor housing 13. Axially, the bearing 27 is located between the motor 5 and the impeller 3, and the bearing 29 is located at the rear end of the rotor 15.

[0024] The inner ring 27a of the bearing 27 is fitted with the outer circumferential surface of the rotor 15 with an interference fit. In this embodiment, the inner ring 27a is fitted with the small-diameter portion 31 of the rotor 15 with an interference fit. With this structure, the inner ring 27a will not move axially relative to the rotor 15. On the other hand, the outer ring 27b of the bearing 27 is fitted with the inner circumferential surface of the motor housing 13 with a clearance fit. Moreover, an abutment portion 13a (abutment part) is provided at the front end of the inner circumferential surface of the motor housing 13. The abutment portion 13a extends radially inward from the inner circumferential surface of the motor housing 13, and the front end face of the outer ring 27b abuts against the abutment portion 13a axially. According to this structure, the outer ring 27b can slide axially relative to the inner circumferential surface of the motor housing 13, but its forward movement is restricted by the abutment portion 13a.

[0025] Furthermore, to prevent creep of the outer ring 27b, the bearing 27 can also be mounted on the motor housing 13 via an O-ring. That is, as... Figure 2 As shown, an O-ring 30 extending circumferentially can also be clamped between the outer peripheral surface of the outer ring 27b and the inner peripheral surface of the motor housing 13.

[0026] like Figure 1 As shown, the inner ring 29a of bearing 29 is fitted with the outer circumferential surface of rotor 15 with an interference fit. Furthermore, the inner ring 29a is embedded in the small-diameter portion 32 located at the rear end of rotor 15, and the front end face of the inner ring 29a abuts against the stepped portion of the small-diameter portion 32. With this structure, the inner ring 29a will not move axially relative to rotor 15. On the other hand, the outer ring 29b of bearing 29 is fitted with the inner circumferential surface of motor housing 13 with a clearance fit, thus allowing the outer ring 29b to slide axially relative to the inner circumferential surface of motor housing 13. Additionally, bearing 29 can also be disposed in motor housing 13 via an O-ring, similar to bearing 27.

[0027] Furthermore, bearings 27 and 29 are angular contact ball bearings to function as both radial and thrust bearings. Bearing 27 is positioned to support the forward thrust (thrust from motor 5 towards impeller 3) of the rotor 15. That is, when the inner ring 27a of bearing 27 receives a forward thrust from the rotor 15, this thrust is transmitted to the outer ring 27b via ball 27c. Similarly, bearing 29 is positioned to support the rearward thrust (thrust from impeller 3 towards motor 5) of the rotor 15. That is, when the inner ring 29a of bearing 29 receives a rearward thrust from the rotor 15, this thrust is transmitted to the outer ring 29b via ball 29c.

[0028] Within the motor housing 13, in the space behind the rotor 15, are arranged a compression coil spring 35 (pressure spring) that extends and retracts axially, and a retainer 37 that applies force forward through the coil spring 35 to compress the rotor 15. The retainer 37 is circular and has a protruding rib 37a that protrudes forward along its front edge. The front end face of this protruding rib 37a abuts against the rear end face of the outer ring 29b of the bearing 29. With this configuration, the force of the coil spring 35 applies force forward to the outer ring 29b of the bearing 29 via the retainer 37.

[0029] According to the bearing structure described above, when the outer ring 29b is pushed forward by the force of the coil spring 35 via the retainer 37, the inner ring 29a is pushed forward via the ball 29c. Thus, the inner ring 29a, through its interference fit with the rotor 15, pushes the rotor 15 forward. Furthermore, the inner ring 27a of the bearing 27, through its interference fit with the rotor 15, pushes the inner ring 27a of the bearing 27 forward. Moreover, by pushing the inner ring 27a forward, the outer ring 27b is pushed forward via the ball 27c, and the outer ring 27b is pressed against the abutment portion 13a of the motor housing 13. Thus, as... Figure 1 As shown, the rotor 15, bearings 27 and 29, and retainer 37 are positioned by abutting against the abutment part 13a under the force of the coil spring 35. This positions the rotor 15, bearings 27 and 29, and retainer 37. Figure 1 The state is called the "initial state", and the position of each part in the initial state is called the "initial position".

[0030] Furthermore, the rotor 15 can resist the force exerted by the helical spring 35 and move rearward from its initial position. To limit the displacement of the rotor 15 to a predetermined level, a limiter 41 is provided at a gap behind the retainer 37. The limiter 41 prevents the rotor 15 from moving beyond a predetermined limit displacement Q, and allows displacement of the rotor 15 not exceeding this limit displacement Q. The limit displacement Q is equivalent to the amount of axial clearance between the rear end face of the retainer 37 and the limiter 41 in the initial state.

[0031] The limiter 41 is composed of a retaining ring (open elastic retaining ring). Specifically, a groove 42 extending circumferentially is formed on the inner circumferential surface of the motor housing 13. The limiter 41 is a C-shaped retaining ring with a portion of the ring cut off. During the assembly of the electric compressor 1, the diameter of the limiter 41 is compressed and inserted into the inner side of the motor housing 13 and embedded in the groove 42, thereby setting the limiter 41. Moreover, since the radial width of the limiter 41 is wider than the depth of the groove 42, the inner circumferential portion of the limiter 41 extends inward from the inner circumferential surface of the motor housing 13. With this structure, when the rotor 15 is displaced to the limit displacement Q, the limiter 41 interferes with the retainer 37, preventing the rotor 15 from moving further rearward. By using a retaining ring as described above to construct the limiter 41, the assembly and disassembly of the limiter 41 portion becomes easy.

[0032] In applications where the electric compressor 1 is mounted in vehicles or aircraft, an impact load can be applied to the operating electric compressor 1. In this case, the rotor 15 generates an axial inertial force due to the axial component of the vibration caused by the impact load. According to the bearing structure described above, the forward inertial force is supported by the abutment portion 13a of the motor housing 13, and the rotor 15 does not displace from its initial position. On the other hand, when a rearward inertial force is applied, this inertial force is supported by the helical spring 35, and by compressing the helical spring 35, the rotor 15 displaces rearward from its initial position. Thus, when the electric compressor 1 vibrates, the rotor 15 displaces axially, but its displacement is limited to a limit displacement Q or less.

[0033] Next, refer to Figure 3 The setting of the limit displacement Q mentioned above will be explained. Figure 3 This is a cross-sectional view showing the retainer 37, limiter 41, and coil spring 35 in their ultimate displacement state; illustrations of components other than those required for explanation are omitted. Additionally, in Figure 3 In the diagram, the retainer 37 in its initial state is represented by a double-dotted line. Hereinafter, the state in which the rotor 15 is displaced by the limit displacement Q (i.e., the state in which the retainer 37 abuts against the limit switch 41) is referred to as the "limit displacement state", and the position of the rotor 15 in the limit displacement state is referred to as the "limit displacement position".

[0034] As described above, the limit displacement Q is equivalent to the amount of clearance between the rear end face of the retainer 37 and the axial direction of the limiter 41 in the initial state. Therefore, the limit displacement Q is appropriately set by properly configuring the limiter 41. The limiter 41 is configured such that all of the following conditions C1 to C4 are satisfied.

[0035] [Condition C1] The length L of the helical spring 35 under the limit displacement state is the length above the tight contact height of the helical spring 35.

[0036] That is, the helical spring 35 in the limit displacement state is in a state where there is still residual capacity that has been compressed axially. Assuming there is no limiter 41, the retainer 37 can further compress the helical spring 35 from the limit displacement state and move backward.

[0037] Here, if the use state of the helical spring 35 is designed according to Section 6.1 of JIS B 2704-1:2018, then the following formula (1) is satisfied for the length L1 of the helical spring 35 during use.

[0038] 20%≤(L0-L1) / (L0-Lc)≤80%…(1)

[0039] Therefore, in this case, as an example of the range that satisfies condition C1, the length L of the helical spring 35 in the limit displacement state is set within the range that satisfies the following formula (2), that is, the configuration of the limiter 41 is set to satisfy the following formula (2).

[0040] 20%≤(L0-L) / (L0-Lc)≤80%…(2)

[0041] In equations (1) and (2), L0 is the free length of the helical spring 35, and Lc is the contact height of the helical spring 35.

[0042] The "close contact height" of the coil spring 35 in condition C1 above can be determined through prior testing. Alternatively, if a commercially available generic coil spring 35 is used, the "close contact height" in condition C1 above can be determined based on the specifications of that generic product. Furthermore, the "close contact height" in condition C1 above refers to the "close contact height" as defined in JIS B 2704-1:2018.

[0043] [Condition C2] The limit displacement Q is less than the minimum offset (hereinafter α) that causes the balls of bearing 27 to fall off when the inner ring 27a and outer ring 27b of bearing 27 are offset relative to each other in the axial direction.

[0044] That is, even if the inner ring 27a and the outer ring 27b of bearing 27 are offset relative to each other in the axial direction, the balls of bearing 27 will not fall out if the offset is less than α. The minimum offset α between the inner ring 27a and the outer ring 27b that would cause the balls of bearing 27 to fall out can be determined through prior experiments.

[0045] [Condition C3] The helical spring 35 under the limit displacement state is in a state of repulsive force to maintain elasticity.

[0046] That is, if the deformation state of the helical spring 35 under the limit displacement state is within the elastic deformation region, and the rotor 15 moves forward, then the helical spring 35 elastically resets. The helical spring 35 reversibly elastically deforms between the initial state and the limit displacement state. The range of "maintaining the elastic repulsive force state" in condition C3 above can be determined through prior experimentation. Alternatively, if a commercially available generic helical spring 35 is used, the range of "maintaining the elastic repulsive force state" in condition C3 above can be determined based on the specifications of that generic product.

[0047] [Condition C4] When the rotor 15 thermally expands axially relative to the motor housing 13, an axial gap remains between the rear end face of the retainer 37 and the limiter 41 in the initial state.

[0048] Due to the heat generated during the operation of the electric compressor 1, the rotor 15 and the motor housing 13 undergo axial thermal expansion. At this time, when the rotor 15 elongates more along its axis than the motor housing 13, this difference in thermal expansion is absorbed by the contraction of the helical spring 35. According to condition C4, even when the axial thermal expansion of the rotor 15 relative to the motor housing 13 reaches its maximum, an axial gap still remains between the rear end face of the retainer 37 and the limiter 41.

[0049] Next, the effects of the electric compressor 1 will be explained. In the electric compressor 1, a limit switch 41 is provided to satisfy the configuration of conditions C1 to C4 mentioned above.

[0050] The effects produced by satisfying condition C2 are as follows. Figure 4 (a) represents the positional relationship of rotor 15, bearings 27, 29, etc. in the initial state. Figure 4 (b) represents the positional relationship of rotor 15, bearings 27, 29, etc., under the limit displacement state. Figure 4 The diagrams of components other than those required for explanation are omitted. During the operation of the electric compressor 1, due to differences in thermal expansion of various components, the outer ring 27b of the bearing 27 may sometimes be in an interference fit with the motor housing 13. Alternatively, an O-ring 30 may exist between the outer ring 27b and the motor housing 13 (see reference). Figure 2 In some cases, due to the friction of the O-ring 30, the outer ring 27b and the motor housing 13 may not slide smoothly along the axial direction.

[0051] In this state, if we consider the backward inertial force acting on rotor 15, causing rotor 15 to displace by a limit displacement Q, then as follows: Figure 4As shown in (b), the rotor 15, bearing 29, and the inner ring 27a of bearing 27 are displaced rearward, while the outer ring 27b, fixed to the motor housing 13, cannot follow this displacement. As a result, the inner ring 27a is displaced axially rearward relative to the outer ring 27b, i.e., the inner ring 27a and outer ring 27b are offset axially. Furthermore, as... Figure 4 As shown in (b), the maximum offset is the limit displacement Q.

[0052] In the case of angular contact ball bearings, if the axial offset between the inner ring 27a and the outer ring 27b is greater than α, ball shedding is likely, and bearing 27 is prone to disintegration. In contrast, in the electric compressor 1, by satisfying the aforementioned condition C2, the limiting displacement Q is made less than α. Therefore, the displacement of the rotor 15 during operation is suppressed to be less than α, thus preventing the axial offset between the inner ring 27a and the outer ring 27b from exceeding α. Therefore, bearing 27 disintegration is avoided during operation.

[0053] Here, if we consider the case where condition C1 is not met, the coil spring 35 is compressed to the contact height before the retainer 37 interferes with the limiter 41. Therefore, the coil spring 35 cannot shrink further, and further rearward displacement of the retainer 37 is prohibited. Thus, when condition C1 is not met, the retainer 37 does not interfere with the limiter 41, and the limiter 41 has no function. In contrast, in the electric compressor 1, when condition C1 is met, and the rotor 15 displaces rearward during operation, the limiter 41 prevents the rotor 15 from displacing rearward before the coil spring 35 reaches the contact height.

[0054] Furthermore, if equation (2) in condition C1 is not satisfied (especially if (L0-L) / (L0-Lc) exceeds 80%), the length L1 of the coil spring 35 will deviate from the range of equation (1) before the retainer 37 interferes with the limiter 41, which is therefore undesirable. In contrast, if equation (2) is satisfied in the electric compressor 1, then when the rotor 15 is displaced rearward during operation, the limiter 41 prevents the rotor 15 from displaced rearward before the length L1 of the coil spring 35 deviates from the range of equation (1). Therefore, the deformation of the coil spring 35 can be suppressed within the range of Section 6.1 of JIS B 2704-1:2018.

[0055] Furthermore, by satisfying condition C3, even when the rotor 15 is displaced by the limit displacement Q, the helical spring 35 is prevented from deforming beyond its elastic deformation zone. As a result, damage to the helical spring 35, such as residual irreversible deformation, is avoided. In addition, by satisfying condition C4, the axial thermal expansion difference between the rotor 15 and the motor housing 13 during operation can be absorbed by utilizing the gap between the rear end face of the retainer 37 and the limiter 41.

[0056] Furthermore, to suppress the axial displacement of the inner ring 27a and outer ring 27b of the bearing 27 during operation, a structure that increases the spring stiffness of the helical spring 35 can be used instead of the limiter 41. However, with this structure, the installation dimensions of the helical spring 35 need to be managed with high precision, which can be a major reason for the increased manufacturing cost of the electric compressor 1. In addition, if the spring stiffness of the helical spring 35 is increased, the reaction force of the helical spring 35 caused by dimensional changes due to thermal expansion and other factors will increase. As a result, the friction between the ball 27c, the inner ring 27a, and the outer ring 27b in the bearing 27 increases, thus increasing the thermal aging of the grease and shortening the life of the bearing 27. Similarly, the life of the bearing 29 also decreases. In contrast, the electric compressor 1 avoids the above problems.

[0057] This disclosure can be implemented from the above-described embodiments with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, variations can be constructed using the technical aspects described in the above-described embodiments. The structures of various embodiments can also be appropriately combined.

[0058] For example, the structure of the electric compressor 1 equipped with limiter 41 is particularly necessary in situations where electric compressors mounted in vehicles, aircraft, etc., are randomly subjected to vibration and impact, and can be preferably applied. Furthermore, not only for electric compressors mounted in vehicles and aircraft, but also for those used for installation, the structure of the electric compressor 1 equipped with limiter 41 can be applied as a measure to mitigate earthquake vibrations. Additionally, in the above embodiment, bearings 27 and 29 are angular contact ball bearings, but bearings 27 and 29 are not limited to this and can also be deep groove bearings.

[0059] Figure 5 (a) to (c) are cross-sectional views showing a modified example near the retainer 37. Figure 5 The diagram shows the area near the retainer 37 in its initial state, omitting illustrations of components other than those required for explanation. As a limiter restricting the displacement of the rotor 15, any device provided on the motor housing 13 that directly or indirectly interferes with the displacement of the rotor 15 is acceptable, and it is not limited to the limiter 41, which is a retaining ring. For example, the limiter 41 can be replaced by, for example, […]. Figure 5As shown in (a), an annular stopper 45 may also be provided behind the retainer 37 along the inner circumferential surface of the motor housing 13. Alternatively, for example, as... Figure 5 As shown in (b), a stepped limiter 46 that interferes with the retainer 37 can also be provided on the inner circumferential surface of the motor housing 13 behind the retainer 37. In addition, although the limiters 41, 45, and 46 interfere with the retainer 37 (i.e., indirectly interfere with the rotor 15), they can also be configured to directly interfere with the rotor 15.

[0060] Additionally, a limiter, serving as a means to restrict the displacement of the rotor 15, can be directly or indirectly disposed on the rotor 15, moving with the rotor 15 and interfering with the motor housing 13. As an example, for instance, such as... Figure 5 As shown in (c), a rearwardly protruding limiter 47 may also be provided on the rear side of the retainer 37. The limiter 47 is housed in the space of the hollow portion of the coil spring 35, and the rear end face of the limiter 47 is separated from the inner wall surface 13d of the motor housing 13 by a gap corresponding to the limit displacement Q. In addition, the limiter is not limited to being provided on the retainer 37 (i.e., the limiter indirectly provided on the rotor 15), and it is also possible for the limiter directly provided relative to the rotor 15 to interfere with the inner wall of the motor housing 13.

[0061] Explanation of reference numerals in the attached figures

[0062] 1... Electric compressor; 2... Compressor section; 5... Motor; 13... Motor housing; 13a... Abutting part (abutting area); 15... Rotor; 27... Bearing (rolling bearing); 27a... Inner ring; 27b... Outer ring; 35... Helical spring (compression spring); 41, 45, 46, 47... Limiters; H... Rotation axis; Q... Limit displacement.

Claims

1. An electric compressor, characterized in that, have: The housing of the motor that serves as the power source for the compressor unit; A rotor that rotates within the housing about a predetermined axis of rotation; A compression spring that applies force to the rotor along the direction of the rotation axis; A rolling bearing, sandwiched between the housing and the motor, has: an inner ring held in place of the rotor; and an outer ring abutting against a predetermined abutment portion of the housing along the axis of rotation by the force of the compression spring. as well as A limit switch prevents the rotor from displacing beyond a predetermined limit against the force of the compression spring, and allows the rotor to displace within the limit. When the rotor displacement reaches the limit displacement, the deformed compression spring has a length exceeding the contact height. The abutment portion is located at the front end of the inner circumferential surface of the housing, and extends radially inward from the inner circumferential surface of the housing. The front end face of the outer ring abuts against the abutting portion in the direction of the rotation axis. The rolling bearing functions as both a radial bearing and a thrust bearing, and is positioned to support the thrust from the motor toward the impeller.

2. The electric compressor according to claim 1, characterized in that, When the length of the deformed compression spring after the rotor is displaced to the limit displacement is set to L, the free length of the compression spring is set to L0, and the contact height of the compression spring is set to Lc, the following formula is satisfied: 20%≤(L0-L) / (L0-Lc)≤80%.

3. The electric compressor according to claim 1 or 2, characterized in that, The limit displacement is less than the minimum offset that causes ball slippage when the inner and outer rings of the rolling bearing are offset relative to each other in the direction of the rotation axis.

4. The electric compressor according to claim 1 or 2, characterized in that, The rolling bearing is an angular contact ball bearing.

5. The electric compressor according to claim 1 or 2, characterized in that, When the rotor is displaced to the limit displacement, the deformed compression spring is in a state of maintaining elastic repulsive force.

6. The electric compressor according to claim 1 or 2, characterized in that, The limiter is disposed on the housing, and the rotor after displacement interferes directly or indirectly with the limiter.

7. The electric compressor according to claim 6, characterized in that, The limiter is a retaining ring that is embedded in a groove extending circumferentially on the inner circumferential surface of the housing.

8. The electric compressor according to claim 1 or 2, characterized in that, The limiter is disposed directly or indirectly on the rotor and moves together with the rotor, thus interfering with the housing.

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