JP4517870B2 - Fastening structure and manufacturing method of rotor shaft - Google Patents

Description

  The present invention relates to a structure for fastening a rotor shaft of an electric motor in which a rotor core is press-fitted into the shaft, and a method for manufacturing the rotor shaft.

The rotor shaft of an electric motor is configured by providing a shaft at the center of a core formed of laminated steel plates, and these rotor core and shaft are configured to be fastened integrally with each other (for example, Patent Document 1).
JP-A-8-9575 (2nd page, Fig. 1)

  However, since the rotor shaft transmits torque under conditions of high rotation and high temperature, a tightening margin required to prevent relative rotation is required between the rotor core and the shaft, and particularly high torque is required for electric vehicles and the like. It becomes remarkable in the electric motor.

  For this reason, the rotor core and the shaft need to be firmly connected by expansion press-fitting of the rotor core by shrink fitting or contraction press-fitting of the shaft by cooling fitting.When performing press fitting by a temperature difference in this way, the rotor core is heated, or It takes time to cool the shaft, and the manufacturing efficiency of the rotor shaft is reduced.

  Therefore, if you try to press-fit the rotor core and shaft directly so that they can withstand the required torque by eliminating shrink fitting and cooling fitting to reduce the work time, the tightening margin will inevitably become too large. May cause excessive stress.

  In addition, as disclosed in Patent Document 1, when an insulating collar is interposed between the rotor core and the shaft, the heat generated in the rotor core cannot be efficiently transmitted to the shaft, and refrigerant is supplied to the shaft. The cooling efficiency of the rotor shaft also deteriorates when it is circulated and cooled.

  SUMMARY OF THE INVENTION Therefore, the present invention provides a rotor shaft fastening structure and a manufacturing method capable of preventing the generation of excessive stress on the shaft and the rotor core and improving the cooling efficiency of the rotor shaft while improving the manufacturing efficiency of the rotor shaft. Is to provide.

  The present invention is a rotor shaft configured by press-fitting a rotor core into a shaft. In the rotor shaft of the present invention, a groove extending in the axial direction is formed on the outer side of the shaft, the shaft is pressed into the rotor core, and the edges on both sides of the groove are pressed into the inner periphery of the rotor core, and the groove is inserted into the groove. A heat conducting member that contacts both the rotor core and the shaft is disposed.

  According to the present invention, since the grooves extending in the axial direction are formed in the shaft for press-fitting the rotor core, the press-fit load can be reduced by reducing the contact area between the shaft and the rotor core, thereby suppressing the generation of excessive excessive stress. However, the rotor core can be directly press-fitted into the shaft, and thus the manufacturing efficiency of the rotor shaft can be increased.

  Further, since the groove is formed in the shaft, the edges on both sides of the groove can be bitten into the inner periphery of the rotor core at the time of press-fitting to further improve the coupling in the rotational direction, so that the contact area between the shaft and the rotor core is increased. The coupling force in the rotational direction due to the reduction can be compensated (increased), and the transmission torque from the rotor core to the shaft can be further increased.

  Furthermore, since the heat conduction member that contacts the rotor core and the shaft is disposed in the groove, the contact area between the shaft and the rotor core is reduced by the groove formation, and the heat conduction amount is reduced by the heat conduction member. The amount of heat reduction is compensated to ensure the amount of heat conduction from the rotor core to the shaft, and the rotor shaft can be efficiently cooled via the shaft.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

“First Embodiment”
1 to 4 show a first embodiment of a rotor shaft fastening structure and a manufacturing method thereof according to the present invention, FIG. 1 is a front view of the rotor shaft, FIG. 2 is a plan view of the rotor shaft, and FIG. ) Is an explanatory view of the heat conducting member shown in a developed state and (b) is a cross section in a bent state, and FIG. Note that FIG. 4 does not have the same size as the rotor shaft of FIGS. 1 and 2 in order to facilitate understanding of the manufacturing method.

  The rotor shaft 10 of the present embodiment is configured as an output shaft of an electric motor, and includes a shaft 11 and a rotor core 12 that are formed separately as shown in FIGS. 1 and 2, and the center of the rotor core 12 is arranged on the outer periphery of the shaft 11. The opening 12a is press-fitted and coupled together.

  The shaft 11 is formed in a hollow cylindrical shape having a through-hole 11a on the central axis and having a predetermined thickness t, and is formed with rotation support portions 11b and 11c with reduced diameters at the outer periphery of both ends.

  The rotor core 12 is formed in a cylindrical shape by a laminated steel plate in which a large number of steel plates are laminated to a predetermined thickness T, and is formed in a ring shape as a whole by forming the central opening 12a at the center thereof.

  Here, in the fastening structure of the rotor shaft 10 of the present embodiment, a groove 20 extending in the axial direction is formed outside the shaft 11, the shaft 11 is formed in the rotor core 12, and edges 20 E on both sides of the groove 20 are formed in the rotor core 12. A high thermal conductivity soft sheet 30 as a heat conductive member that contacts both the rotor core 12 and the shaft 11 is disposed in the groove 20 while being pressed into the inner periphery of the rotor.

  As the high thermal conductivity soft sheet 30, a heat conductive sheet having elasticity such as a PGS graphite sheet (manufactured by Matsushita Electronic Components), an aluminum alloy sheet, a magnesium alloy sheet, a stainless steel sheet or the like is used, as shown in FIG. The groove 20 is formed in a shape in which the bottom 20a of the groove 20 and the inner periphery of the rotor core 12 are pressed with elasticity.

  That is, the high thermal conductivity flexible sheet 30 is formed in a rectangular shape having a length T ′ substantially equal to the thickness T (see FIG. 1) of the rotor core 12 as shown in FIG. , 30b are bent from one side to the other side of the folding line 30c as shown in FIG.

  As shown in FIG. 2, the high thermal conductivity flexible sheet 30 has a central portion 30 d disposed on the bottom portion 20 a of the groove 20, and bent side portions 30 a and 30 b are disposed on the inner periphery of the central opening 12 a of the rotor core 12. It is made to contact.

  In addition, the method of manufacturing the rotor shaft 10 according to the present embodiment includes a groove forming step of forming the axially extending groove 20 on the outer side of the shaft 11, and the shaft 11 having the groove 20 formed on the rotor core 12 at the edges on both sides of the groove 20. A press-fitting step of press-fitting 20E into the inner periphery of the rotor core 12, and a heat-conducting member mounting step of disposing a high thermal conductivity soft sheet 30 as a heat-conducting member in contact with both the rotor core 12 and the shaft 11 in the groove 20 And it comes to manufacture with.

  At this time, in the press-fitting step, as shown in FIG. 4, after the rotor core 12 is fixed to a base (not shown), the shaft 11 is pressed into the central opening 12a for press-fitting. At this time, the high thermal conductivity soft sheet 30 is bonded to the groove 20 of the shaft 11 by an adhesive or welding, and the shaft 11 is press-fitted into the rotor core 12 together with the high thermal conductivity soft sheet 30.

  In FIG. 4, the shaft 11 is shown as a cylindrical tube having the same diameter over the entire length for the sake of convenience. Actually, however, the rotary support portions 11b and 11c having reduced diameters at both axial end portions thereof as shown in FIG. It is formed.

  With the above structure, according to the fastening structure of the rotor shaft 10 of the present embodiment, since the axially extending groove 20 is formed in the shaft 11 into which the rotor core 12 is press-fitted, the contact area between the shaft 11 and the rotor core 12 is reduced. Since the press-fitting load can be reduced, the rotor core 12 can be directly press-fitted into the shaft 11 while suppressing excessive excessive stress. For this reason, since it is not necessary to perform shrink fitting or cooling fitting at the time of press fitting, the manufacturing efficiency of a rotor shaft can be improved.

  In addition, since the groove 20 is formed in the shaft 11, the edge 20 E on both sides of the groove 20 can be bitten into the inner periphery of the rotor core 12 during press-fitting to further improve the coupling in the rotational direction. The coupling force in the rotational direction due to the reduction of the contact area with the rotor core 12 can be compensated, and the transmission torque from the rotor core 12 to the shaft 11 can be further increased.

  Furthermore, since the high thermal conductivity soft sheet 30 that contacts the rotor core 12 and the shaft 11 is disposed in the groove 20, the contact area between the shaft 11 and the rotor core 12 is reduced by the formation of the groove 20. The above-described high thermal conductivity soft sheet 30 compensates for the reduction of the contact area to secure the required amount of heat conduction from the rotor core 12 to the shaft 11 and to efficiently cool the rotor shaft 10 via the shaft 11. Can do.

  That is, the shaft 11 has a through-hole 11a formed on the central axis, and the coolant can be efficiently flowed through the through-hole 11a so that the cooling effect of the rotor core 12 can be enhanced.

“Second Embodiment”
FIG. 5 shows a second embodiment of the present invention, in which the same components as those in the first embodiment are denoted by the same reference numerals and redundant description is omitted, and FIG. 5 shows the manufacturing process of the rotor shaft. It is sectional drawing.

  The configuration of the rotor shaft 10 of this embodiment is basically the same as that of the first embodiment, and the manufacturing method is similarly manufactured by a groove forming process, a press-fitting process, and a heat conducting member mounting process.

  In particular, in the present embodiment, as shown in FIG. 5, in the manufacturing process of the rotor shaft 10, a cylindrical guide jig 40 is set coaxially with the central opening 12 a on the peripheral upper surface of the central opening 12 a of the rotor core 12, The shaft 11 is press-fitted into the rotor core 12 through the guide jig 40.

  That is, while the guide jig 40 is set on the rotor core 12, the high thermal conductivity soft sheet 30 is bonded to the groove 20 of the shaft 11 as in the first embodiment, and in this state, the high thermal conductivity soft sheet is provided. 30, the shaft 11 is inserted into the guide jig 40, and the projecting end of the shaft 11 is pressed through the pushing jig 40 to press-fit the shaft 11 into the rotor core 12. The tool 40 is removed.

  Of course, in the present embodiment as well, the groove 20 extending in the axial direction is formed outside the shaft 11 as in the first embodiment. The shaft 11 is formed in the rotor core 12 and the edges 20E on both sides of the groove 20 are formed in the rotor core 12. The high-heat-conductivity soft sheet 30 disposed in the groove 20 is brought into contact with both the rotor core 12 and the shaft 11.

  Accordingly, even in the present embodiment, as in the first embodiment, by forming the groove 20 extending in the axial direction in the shaft 11, the rotor core 12 can be directly press-fitted into the shaft 11, and the groove at the time of press-fitting. The edge 20E on both sides of the rotor 20 can be cut into the inner periphery of the rotor core 12 to further improve the coupling in the rotational direction, and the high thermal conductivity soft sheet 30 is disposed in the groove 20, so that the shaft 11 is removed from the rotor core 12. The heat conduction efficiency to the can be increased.

“Third Embodiment”
FIG. 6 shows a third embodiment of the present invention, in which the same components as those in the first embodiment are denoted by the same reference numerals and redundant description is omitted, and FIG. 6 shows the manufacturing process of the rotor shaft. It is sectional drawing.

  The configuration of the rotor shaft 10 of this embodiment is basically the same as that of the first embodiment, and the manufacturing method is similarly manufactured by a groove forming process, a press-fitting process, and a heat conducting member mounting process.

  In particular, in the present embodiment, as shown in FIG. 6, in the manufacturing process of the rotor shaft 10, first, only the shaft 11 is press-fitted into the rotor core 12, and then a guide jig 40 </ b> A is fitted into the shaft 11. After that, the high thermal conductivity soft sheet 30 is temporarily inserted into the guide jig 40A, and the pressing jig 41A is inserted into the guide jig 40A to press the high thermal conductivity soft sheet 30, and this high thermal conductivity The flexible sheet 30 is inserted into a predetermined position in the groove 20 of the shaft 11.

  In this case, after the guide jig 40A is fitted to the shaft 11, the high thermal conductivity soft sheet 30 is temporarily inserted. However, the present invention is not limited thereto, and the high thermal conductivity soft sheet 30 is temporarily inserted into the guide jig 40A. Later, the guide jig 40 </ b> A can be fitted to the shaft 11.

  Accordingly, even in the present embodiment, as in the first embodiment, by forming the groove 20 extending in the axial direction in the shaft 11, the rotor core 12 can be directly press-fitted into the shaft 11, and in the rotational direction. The bondability can be further increased, and the heat conduction efficiency from the rotor core 12 to the shaft 11 can be enhanced by the high thermal conductivity flexible sheet 30.

"Other embodiments"
By the way, although this invention was demonstrated taking the example in the said 1st-3rd embodiment, various embodiments can be employ | adopted in the range which does not deviate from the summary of this invention, without being restricted to these embodiments, For example, in order to bring the high thermal conductivity soft sheet 30 into pressure contact with the bottom 20a of the groove 20 and the inner periphery of the rotor core 12 with elasticity, the shape is not limited to the shape shown in FIG. It can be formed as a shape shown in a) to (d).

  That is, the high thermal conductivity flexible sheet 30A shown in FIG. 7 (a) is formed into a corrugated shape, and the high thermal conductivity flexible sheet 30B shown in FIG. 7 (b) is formed in two, and the high thermal conductivity shown in FIG. 7 (c). The flexible sheet 30C is formed in a spiral and is folded in three, and the high thermal conductivity flexible sheet 30D shown in FIG.

It is a front view of the rotor shaft in 1st Embodiment of this invention. It is a top view of the rotor shaft in 1st Embodiment of this invention. It is explanatory drawing of the heat conductive member shown by the expanded state in (a) and the cross section of a bent state in (b) in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the rotor shaft in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the rotor shaft in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the rotor shaft in 3rd Embodiment of this invention. It is sectional drawing which shows the other example of a high thermal conductivity soft sheet, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Rotor shaft 11 ... Shaft 12 ... Rotor core 20 ... Groove 20a ... Bottom part 20E ... Edge 30 ... High thermal conductivity soft sheet (heat conduction member)

Claims (4)

A rotor shaft fastening structure configured by press-fitting a rotor core into the shaft,
A groove extending in the axial direction is formed on the outer side of the shaft, and the shaft is pressed into the rotor core while the edges on both sides of the groove are biting into the inner periphery of the rotor core, and heat that contacts both the rotor core and the shaft in the groove. A rotor shaft fastening structure comprising a conductive member. The fastening structure for a rotor shaft according to claim 1,
The structure for fastening a rotor shaft, wherein the heat conducting member is formed in a shape in which the bottom portion of the groove and the inner periphery of the rotor core are pressed with elasticity. The rotor shaft fastening structure according to claim 2,
The structure for fastening a rotor shaft, wherein the heat conducting member is a flexible sheet having a high thermal conductivity arranged in the groove in a bent state. A groove forming step of forming an axially extending groove on the outside of the shaft;
A press-fitting step of press-fitting the shaft formed with the groove into the rotor core while biting the edges on both sides of the groove into the inner periphery of the rotor core;
A method of manufacturing a rotor shaft, comprising: a heat conductive member attaching step of arranging a heat conductive member in contact with both the rotor core and the shaft in the groove.

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