JP2007321675A - Rotating shaft structure and electric supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary shaft structure and a motor-driven supercharger including this structure, capable of restraining the temperature rise in a rotor, without excessively reducing rigidity of a rotary shaft. <P>SOLUTION: This rotary shaft structure has a turbine wheel 121 being an exhaust side wheel of the motor-driven supercharger, a shaft 310 connected to the turbine wheel 121, the rotor 320 fixed to the shaft 310, and a floating bearing 342 arranged on the turbine wheel 121 side to the rotor 320 and supporting the shaft 310. A heat transfer passage formed in the shaft 310 positioned between the turbine wheel 121 and the rotor 320, has a part A positioned between the rotor 320 and the floating bearing 342, and a part B positioned on the floating bearing 342. Here, the cross-sectional area of the heat transfer passage in the part A, is set smaller than the cross-sectional area of the heat transfer passage in the part B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotating shaft structure and an electric supercharger, and more particularly to a rotating shaft structure included in an electric supercharger.

Conventionally, an electric supercharger having a rotating shaft is known.
For example, in Japanese translations of PCT publication No. 2001-527613 (patent document 1), in order to cool the rotating shaft of an electric supercharger, a through hole serving as a cooling passage is formed in the shaft center, and air is circulated through the through hole. The structure which cools a rotating shaft by doing is disclosed.

  Japanese Patent Laid-Open No. 6-173602 (Patent Document 2) discloses a structure in which a low cross-sectional area portion is formed by providing a hole in a turbine wheel side end portion of a rotating shaft.

  In Japanese Patent Laid-Open No. 63-266126 (Patent Document 3), a rotor is disposed on a shaft having a turbine blade fixed to one end, and a shaft between a bearing and a rotor located on the turbine blade side is arranged. A structure in which a ceramic high-rigidity sleeve is fitted to the outer periphery is disclosed.

Japanese Patent Laying-Open No. 2000-145469 (Patent Document 4) discloses a structure in which both ends of a rotor of an electric supercharger are supported by spacers.
JP-T-2001-527613 JP-A-6-173602 JP 63-266126 A JP 2000-145469 A

  The electric supercharger may be operated at a high temperature depending on the usage environment and operating conditions. In particular, the turbine wheel located on the exhaust side is exposed to high temperatures. The heat of the turbine wheel is transmitted to the rotor via the rotating shaft. If this heat transfer amount is large, the temperature of the rotor rises excessively. For example, when a permanent magnet is provided in the rotor, the magnet may be demagnetized and the performance of the electric supercharger may not be ensured. . Therefore, it is important to suppress heat transfer from the turbine shaft to the rotor via the rotating shaft.

  In the structure described in Patent Document 1, a cooling passage that penetrates the entire rotating shaft in the axial direction is formed. However, by doing so, the rigidity of the rotating shaft may be reduced and shaft vibration may be increased. . Also, Patent Documents 2 to 4 do not disclose a configuration that sufficiently solves the above problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a rotary shaft structure capable of suppressing an increase in the temperature of the rotor without excessively reducing the rigidity of the rotary shaft, and It is providing the electric supercharger containing this structure.

  A rotating shaft structure according to the present invention is a rotating shaft structure included in an electric supercharger, and in one aspect, a turbine wheel that is a wheel on an exhaust side of the electric supercharger and a rotation connected to the turbine wheel. A shaft, a rotor fixed to the rotating shaft, and a bearing provided on the turbine wheel side with respect to the rotor and supporting the rotating shaft, are formed in the rotating shaft positioned between the turbine wheel and the rotor. The heat transfer path has a first portion located between the rotor and the bearing portion, and a second portion located on the inner periphery of the bearing portion, and the first portion heat-transfers more than the second portion. A low cross-sectional area portion having a small cross-sectional area of the path is included.

  According to the said structure, it can suppress that the heat from a turbine wheel is transmitted to a rotor by the 1st part of the heat-transfer path located between a rotor and a bearing part including a low cross-sectional area part. it can. Moreover, the rigidity of a rotating shaft can be ensured more than fixed by ensuring the cross-sectional area of the 2nd part of the heat-transfer path | route located in the inner periphery of a bearing part to some extent. Therefore, the temperature rise of the rotor can be suppressed without excessively reducing the rigidity of the rotating shaft.

  Preferably, in the rotary shaft structure, a stepped portion is formed on the outer peripheral surface of the rotary shaft such that the diameter on the turbine wheel side is increased, and the rotor is positioned on the opposite side of the turbine wheel with respect to the stepped portion. A bottomed hole extending in the axial direction of the rotating shaft from the axial end surface of the rotating shaft on the turbine wheel side to reach the vicinity of the stepped portion, and the low cross-sectional area portion is formed by the stepped portion and the bottom of the bottomed hole. Formed between.

  Thereby, the temperature rise of a rotor can be suppressed with a simple structure. Further, by forming the low cross-sectional area portion by the bottomed hole formed only on the turbine shaft side than the vicinity of the stepped portion, it is possible to suppress the increase in the rotor temperature while suppressing the shaft rigidity from being lowered. .

  Preferably, in the rotating shaft structure, the diameter of the bottomed hole located on the turbine wheel side with respect to the bearing portion is made larger than that of the other part of the bottomed hole.

  Thereby, the weight of the rotating shaft located in the outer side (turbine wheel side) rather than a bearing part can be reduced.

  Preferably, the rotating shaft structure further includes spacers provided at both ends in the axial direction of the rotor, and the spacer located on the turbine wheel side has a lower heat transfer coefficient than the rotating shaft.

  Thereby, the heat transfer from the turbine wheel to the rotor can be further suppressed. Therefore, the effect of suppressing the temperature rise of the rotor can be further enhanced.

  Preferably, the rotating shaft structure further includes a compressor wheel which is a wheel on the intake side of the electric supercharger, and spacers provided at both ends in the axial direction of the rotor, and the spacer located on the compressor wheel side is: The heat transfer coefficient is higher than that of the spacer located on the turbine wheel side.

  Thereby, the heat generated in the rotor during operation of the rotating electrical machine can be actively released to the compressor wheel side. Therefore, the effect of suppressing the temperature rise of the rotor can be further enhanced.

  A rotating shaft structure according to the present invention is a rotating shaft structure included in an electric supercharger, and in another aspect, a compressor wheel that is a wheel on an intake side of the electric supercharger, and an exhaust side of the electric supercharger A compressor wheel and a rotating shaft connected to the turbine wheel, a rotor fixed to the rotating shaft, and spacers provided at both ends in the axial direction of the rotor. The spacer located at has a higher heat transfer coefficient than the spacer located on the turbine wheel side.

  According to the above configuration, heat generated in the rotor during operation of the rotating electrical machine can be actively released to the compressor wheel side. Therefore, the temperature rise of the rotor can be suppressed without excessively reducing the rigidity of the rotating shaft.

  The electric supercharger according to the present invention includes the rotary shaft structure described above. Thereby, the electric supercharger in which the temperature rise of the rotor is suppressed without excessively reducing the rigidity of the rotating shaft is obtained.

  According to the present invention, it is possible to suppress an increase in the temperature of the rotor without excessively reducing the rigidity of the rotating shaft.

  Embodiments of the present invention will be described below. Note that the same or corresponding parts are denoted by the same reference numerals, and the description thereof may not be repeated.

  Note that in the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. In the following embodiments, each component is not necessarily essential for the present invention unless otherwise specified. In addition, when there are a plurality of embodiments below, it is planned from the beginning to appropriately combine the features of each embodiment unless otherwise specified.

(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of a system in which a rotating electric machine including a rotating shaft structure according to Embodiment 1 of the present invention is assembled to an engine with a turbocharger (electric supercharger). As shown in FIG. 1, the system includes an engine 100 including an intake pipe 110 and an exhaust pipe 120, a turbocharger 200 including wheels in the intake pipe 110 and the exhaust pipe 120, and a coaxial arrangement with the turbocharger 200. The magnet-type electric motor 300, the inverter 400, and the ECU 500 that controls the entire system are configured. The magnet type electric motor 300 is an electric motor having a rotor in which a magnet is arranged on the outer peripheral portion of a rotating shaft.

  In the system shown in FIG. 1, a turbine wheel 121 that is a wheel on the exhaust pipe 120 side is rotated by exhaust energy discharged from the engine 100, and a compressor wheel 111 that is a wheel on the intake pipe 110 side is rotated by this power. Let By doing in this way, compressed air can be supplied to the engine 100 and filling efficiency can be improved. In the above system, the turbine shaft for connecting the turbine wheel 121 and the compressor wheel 111 is forcibly rotated by the magnet-type electric motor 300 when the exhaust energy is not sufficient. Electric power to the magnet type electric motor 300 is supplied from the inverter 400. ECU 500 controls the operation of inverter 400.

  The exhaust pipe 120 is provided with a bypass that bypasses the turbine wheel. A waste gate valve 130 is disposed in the vicinity of the bypass inlet. When there is no need for supercharging, the waste gate valve 130 is opened.

  FIG. 2 is a cross-sectional view showing a rotating shaft structure included in the magnet type electric motor 300. Referring to FIG. 2, magnet type electric motor 300 includes a shaft 310, a motor rotor 320, a spacer 330, and a floating bearing 340.

  The shaft 310 is a “rotating shaft” that rotates together with the compressor wheel 111 and the turbine wheel 121. The motor rotor 320 is fixed to the shaft 310. The spacer 330 includes spacers 331 and 332 provided on the compressor wheel 111 side and the turbine wheel 121 side with respect to the motor rotor 320. The spacers 331 and 332 include titanium, a titanium alloy, stainless steel, or the like. Floating bearing 340 includes floating bearings 341 and 342 provided on compressor wheel 111 side and turbine wheel 121 side with respect to motor rotor 320. The floating bearing 340 supports the shaft 310 in the radial direction.

  FIG. 3 is a diagram showing the structure of motor rotor 320 shown in FIG. 2 in more detail. Referring to FIG. 3, the motor rotor 320 includes a tubular member 321, a magnet 322, and a fitting member 323. The tubular member 321 is made of a nonmagnetic material such as titanium, for example. The magnet 322 is provided on the inner peripheral side of the tubular member 321. The fitting member 323 is made of a nonmagnetic material such as titanium, for example, and is fitted into the tubular member 321 together with the magnet 322.

  During the operation of the electric supercharger described above, the turbine wheel 121 provided on the exhaust side is particularly exposed to high temperatures. The heat of the turbine wheel 121 is also transmitted to the rotor 320 via the shaft 310. Here, when the amount of heat transfer to the rotor 320 is excessively large and the temperature of the rotor 320 rises to the thermal demagnetization limit temperature of the magnet 322 provided in the rotor 320, the magnet 322 is demagnetized, There is a concern that the performance of the electric supercharger cannot be secured. Even if the temperature of the rotor 320 is equal to or lower than the demagnetization temperature of the magnet 322, the magnetic force of the magnet 322 is governed by the temperature coefficient specific to the material. There is concern about the decline. Therefore, it is important to suppress the transfer of heat from the turbine wheel 121 to the rotor 320.

  Referring to FIG. 2 again, a hole 311 is formed in the shaft 310 located on the turbine wheel 121 side. The hole 311 is formed so as to extend in the shaft axial direction from the axial end surface of the shaft 310 on the turbine wheel 121 side. The bottom surface of the hole 311 is located between the floating bearing 342 and the spacer 332. That is, the hole 311 is formed so as to reach between the floating bearing 342 and the spacer 332.

  FIG. 9 is a view showing a peripheral structure of the floating bearing 340 (full float bearing) shown in FIG. Referring to FIG. 9, floating bearing 340 is sandwiched between shaft 310 and casing 360 that houses the electric supercharger. However, the floating bearing 340 is not fixed to the shaft 310 and the casing 360. The floating bearing 340 can freely rotate between the shaft 310 and the casing 360. Lubricating oil is filled between the shaft 310 and the floating bearing 340 and between the floating bearing 340 and the casing 360. The floating bearing 340 and its surroundings are cooled by this lubricating oil. C-rings 350 fixed to the casing 360 are provided at both axial ends of the floating bearing 340. As a result, the floating bearing 340 is positioned.

  FIG. 4 is a view showing a structure around the hole 311 in the rotating shaft structure according to the present embodiment. Referring to FIG. 4, stepped portion 310 </ b> A is formed on the outer peripheral surface of shaft 310. The diameter of the shaft 310 positioned on the turbine wheel 121 side with respect to the stepped portion 310A is relatively large, and the diameter of the shaft 310 positioned on the compressor wheel 111 side with respect to the shaft 310A is relatively small. Positioning of the rotor 320 and the spacer 330 (332) as a “rotor” fixed to the shaft 310 is performed by the step portion 310A.

  As shown in FIG. 4, the hole 311 is formed in the shaft 310, thereby reducing the cross-sectional area of the shaft 310. And the part (A part in FIG. 4) where the cross-sectional area of a heat-transfer path becomes smaller than the part (B part in FIG. 4) located in the inner periphery of the floating bearing 342 is formed. Thus, as a result of the cross-sectional area of the heat transfer path from the turbine wheel 121 toward the rotor 320 being reduced in the portion A, the heat from the turbine wheel 121 is difficult to be transmitted to the rotor 320. Then, the heat from the turbine wheel 121 is cooled by the lubricating oil supplied to the floating bearing 342. Since the cross-sectional area of the heat transfer path in part A is reduced, heat transfer to the lubricating oil is promoted.

  The spacer 332 located on the turbine wheel 121 side with respect to the rotor 320 preferably has a lower heat transfer coefficient than the shaft 310, and the spacer 331 located on the compressor wheel 111 side with respect to the rotor 320 is located on the rotor 320. On the other hand, it is preferable that the heat transfer coefficient is higher than that of the spacer 332 located on the turbine wheel 121 side.

  As a material constituting the spacer 330 (331, 332), for example, titanium is used. When the heat transfer coefficient of the spacer 332 is lower than that of the shaft 310 (for example, iron), the spacer 332 is formed. It is conceivable to use titanium or stainless steel as the material to be used. Further, when the heat transfer coefficient of the spacer 331 is made higher than that of the spacer 332 (for example, made of titanium), it is conceivable to use aluminum or iron as a material constituting the spacer 331.

  The above contents are summarized as follows. That is, the rotating shaft structure according to the present embodiment is a rotating shaft structure included in the electric supercharger, and is connected to the turbine wheel 121 that is a wheel on the exhaust side of the electric supercharger and the turbine wheel 121. A shaft 310 as a “rotating shaft”, a rotor 320 fixed to the shaft 310, and a floating bearing 342 as a “bearing portion” provided on the turbine wheel 121 side with respect to the rotor 320 and supporting the shaft 310. Prepare. A heat transfer path formed in the shaft 310 positioned between the turbine wheel 121 and the rotor 320 includes a portion A as a “first portion” positioned between the rotor 320 and the floating bearing 342, and a floating bearing 342. B part as "the 2nd part" located in the upper part. Here, the A part constitutes a “low cross-sectional area part” having a smaller cross-sectional area of the heat transfer path than the B part.

  More specifically, a step portion 310A having a larger diameter on the turbine wheel 121 side is formed on the outer peripheral surface of the shaft 310, and the rotor 320 is positioned on the opposite side of the turbine wheel 121 with respect to the step portion 310A. Fixed to the shaft 310. A hole 311 that is a “bottomed hole” that extends in the axial direction of the shaft 310 from the axial end surface of the shaft 310 on the turbine wheel 121 side and reaches the vicinity of the stepped portion 310A is formed. The A portion which is a “low cross-sectional area portion” is formed between the step portion 310 </ b> A and the bottom portion of the hole portion 311.

  According to the rotating shaft structure according to the present embodiment, the heat from the turbine wheel 121 is transferred to the rotor 320 by reducing the cross-sectional area of the heat transfer path in the part A located between the rotor 320 and the floating bearing 342. It is possible to suppress transmission. Further, by ensuring a certain amount of the cross-sectional area of the heat transfer path in the portion B located on the inner periphery of the floating bearing 342, the rigidity of the shaft 310 can be ensured to a certain level or more. Therefore, the temperature increase of the rotor 320 can be suppressed without excessively reducing the rigidity of the shaft 310.

  Further, by forming the “low cross-sectional area portion” by the hole 311 provided in the shaft 310, the temperature increase of the rotor 320 can be suppressed with a simple structure.

  An antinode of primary vibration that is likely to occur during operation of the electric supercharger is located near the axial center of the shaft 310. In the present embodiment, since the hole 311 is formed only between the axial end of the shaft 310 and the spacer 332, the shaft rigidity does not decrease at a portion close to the antinode of the primary vibration. Therefore, the influence on the vibration characteristics by forming the hole 311 is small.

  Further, when the heat transfer coefficient of the spacer 332 is lower than the heat transfer coefficient of the shaft 310, heat transfer from the turbine wheel 121 to the rotor 320 can be further suppressed. Therefore, the effect of suppressing the temperature rise of the rotor 320 can be further enhanced.

  Further, when the heat transfer coefficient of the spacer 331 is higher than the heat transfer coefficient of the spacer 332, the heat generated in the rotor 320 during the operation of the rotating electrical machine is positively released to the lubricating oil of the floating bearing 341 on the compressor 111 side. be able to. Therefore, the effect of suppressing the temperature rise of the rotor 320 can be further enhanced.

(Embodiment 2)
FIG. 5 is a cross-sectional view showing a rotating shaft structure according to the second embodiment. FIG. 6 is a view showing the structure around the hole 311 in the rotating shaft structure shown in FIG. Referring to FIGS. 5 and 6, the rotating shaft structure according to the present embodiment is a modification of the rotating shaft structure according to the first embodiment, and includes a small diameter portion 311 </ b> A and a large diameter portion 311 </ b> B in hole 311. Is provided. More specifically, the diameter of the hole 311 located on the turbine wheel 121 side with respect to the floating bearing 342 is made larger than the other part of the hole 311, thereby reducing the small diameter part 311 </ b> A and the large diameter part 311 </ b> B. Forming.

  Also in the present embodiment, in the same manner as in the first embodiment, in the portion of the shaft 310 located between the rotor 320 and the floating bearing 342, the portion located on the inner periphery of the floating bearing 342 (B portion in FIG. 6). ) Is formed (part A in FIG. 6) where the cross-sectional area of the heat transfer path is smaller. As a result, the heat from the turbine wheel 121 can be suppressed from being transmitted to the rotor 320 while suppressing the rigidity of the shaft 310 from excessively decreasing.

  Moreover, in this Embodiment, the weight of the shaft 310 which is a rotary body can be reduced by enlarging the diameter of the hole 311 as mentioned above. Here, by enlarging the diameter of the hole 311 located on the outer side (turbine wheel 121 side) than the floating bearing 342, the portion having a great influence on the vibration characteristics (located on the axial center side with respect to the floating bearing 342). The rigidity of the shaft 310 does not decrease. As a result of the above, the vibration characteristics of the shaft 310 are improved.

(Embodiment 3)
FIG. 7 is a cross-sectional view showing a rotating shaft structure according to the third embodiment. Referring to FIG. 7, the rotating shaft structure according to the present embodiment is a modification of the rotating shaft structure according to the first and second embodiments, and a small diameter portion 311 </ b> A and a large diameter portion 311 </ b> B are provided in hole 311. In addition, the turbine wheel 121 is also provided with a hole 121A.

  Also in the present embodiment, as in the second embodiment, the weight of the rotating body including the shaft 310 can be reduced without reducing the rigidity of the portion of the shaft 310 that greatly affects the vibration characteristics. As a result, the vibration characteristics of the shaft 310 are improved.

(Embodiment 4)
FIG. 8 is a cross-sectional view showing a rotating shaft structure according to the fourth embodiment. Referring to FIG. 8, the rotating shaft structure according to the present embodiment is a modification of the rotating shaft structure according to the first to third embodiments, in which hole 311 is omitted, and rotor 320 is replaced by spacer 330 instead. It is characterized in that the temperature rise of the is suppressed.

More specifically,
(1) The heat transfer coefficient of the spacer 332 is set lower than the heat transfer coefficient of the shaft 310,
(2) The heat transfer coefficient of the spacer 331 is set higher than the heat transfer coefficient of the spacer 332.

  That is, the rotating shaft structure according to the present embodiment includes a compressor wheel 111 that is a wheel on the intake side of the electric supercharger, a turbine wheel 121 that is a wheel on the exhaust side of the electric supercharger, and the compressor wheel 111 and the turbine. The spacer 310 provided with the shaft 310 connected to the wheel 121, the rotor 320 fixed to the shaft 310, and the spacers 330 provided at both ends in the axial direction of the rotor 320, and located on the turbine wheel 121 side, The heat transfer coefficient is lower than that of the shaft 310, and the spacer 331 located on the compressor wheel 111 side has a higher heat transfer coefficient than the spacer 332 located on the turbine wheel 121 side.

  Thus, heat transfer from the turbine wheel 121 to the rotor 320 is suppressed, and heat generated in the rotor 320 during the operation of the rotating electrical machine is positively released to the lubricating oil of the floating bearing 341 on the compressor 111 side. be able to. As a result, the temperature rise of the rotor 320 is suppressed. Note that only one of the above (1) and (2) may be satisfied.

  Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows schematic structure of the system which assembled | attached the rotary electric machine containing the rotating shaft structure which concerns on Embodiment 1 of this invention to the engine with a turbocharger. It is sectional drawing which showed the rotating shaft structure which concerns on Embodiment 1 of this invention. It is the figure which showed the structure of the rotor shown by FIG. 2 in detail. It is the figure which showed the structure of the periphery of the shaft hole part in the rotating shaft structure which concerns on Embodiment 1 of this invention. It is sectional drawing which showed the rotating shaft structure which concerns on Embodiment 2 of this invention. It is the figure which showed the structure of the periphery of the shaft hole part in the rotating shaft structure which concerns on Embodiment 2 of this invention. It is sectional drawing which showed the rotating shaft structure which concerns on Embodiment 3 of this invention. It is sectional drawing which showed the rotating shaft structure which concerns on Embodiment 4 of this invention. It is the figure which showed the surrounding structure of the floating bearing.

Explanation of symbols

  100 Engine, 110 Intake pipe, 111 Compressor wheel, 120 Exhaust pipe, 121 Turbine wheel, 121A hole, 130 Wastegate valve, 200 Turbocharger, 300 Magnet type motor, 310 Shaft, 310A Stepped part, 311 hole, 311A Small diameter Part, 311B large diameter part, 320 rotor, 321 tubular member, 322 magnet, 323 fitting member, 330, 331, 332 spacer, 340 floating bearing, 350 C ring, 360 casing, 400 inverter, 500 ECU.

Claims (7)

A rotating shaft structure included in the electric supercharger,
A turbine wheel that is an exhaust-side wheel of the electric supercharger;
A rotating shaft connected to the turbine wheel;
A rotor fixed to the rotating shaft;
A bearing portion provided on the turbine wheel side with respect to the rotor, and supporting the rotating shaft;
A heat transfer path formed in the rotating shaft located between the turbine wheel and the rotor is located on a first portion located between the rotor and the bearing portion and on an inner circumference of the bearing portion. A second part to
The first part includes a rotary shaft structure including a low cross-sectional area part in which a cross-sectional area of a heat transfer path is smaller than that of the second part. A stepped portion is formed on the outer peripheral surface of the rotating shaft such that the diameter on the turbine wheel side is increased,
The rotor is fixed to the rotating shaft so as to be located on the opposite side of the turbine wheel with respect to the stepped portion,
A bottomed hole extending in the axial direction of the rotating shaft from the axial end surface of the rotating shaft on the turbine wheel side and reaching the vicinity of the stepped portion is formed,
The rotating shaft structure according to claim 1, wherein the low cross-sectional area portion is formed between the stepped portion and a bottom portion of the bottomed hole.   The rotating shaft structure according to claim 1 or 2, wherein a diameter of the bottomed hole located on the turbine wheel side with respect to the bearing portion is larger than that of the other part of the bottomed hole. Further comprising spacers provided at both axial ends of the rotor;
The rotating shaft structure according to any one of claims 1 to 3, wherein the spacer located on the turbine wheel side has a heat transfer coefficient lower than that of the rotating shaft. A compressor wheel that is a wheel on the intake side of the electric supercharger;
Spacers provided at both ends in the axial direction of the rotor,
The rotating shaft structure according to any one of claims 1 to 4, wherein the spacer located on the compressor wheel side has a higher heat transfer coefficient than the spacer located on the turbine wheel side. A rotating shaft structure included in the electric supercharger,
A compressor wheel that is a wheel on the intake side of the electric supercharger;
A turbine wheel that is an exhaust-side wheel of the electric supercharger;
A rotating shaft connected to the compressor wheel and the turbine wheel;
A rotor fixed to the rotating shaft;
Spacers provided at both ends in the axial direction of the rotor,
The said spacer located in the said compressor wheel side is a rotating shaft structure whose heat transfer rate is higher than the said spacer located in the said turbine wheel side.   The electric supercharger containing the rotating shaft structure in any one of Claims 1-6.

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