Rotor shaft

Abstract

To provide a rotor shaft having a boiling-cooling function that can reduce a load applied to a sealing member for sealing a filling space of a working fluid and maintain favorable sealing performance.SOLUTION: A rotor shaft 1 forming a rotor R of a rotary electric machine includes a rotor core 11 and rotor shafts 12 and 13 connected to both ends of the rotor core 11 on a common central axis. The rotor core 11 includes a boiling part S1 filled with a working fluid F, and one of the rotor shafts 12 includes a condensation part S3 communicating with the boiling part S1. A through-hole 8 communicating between the inside and the outside of the rotor core 11 is formed in one of the tip portion of the condensation part S3 and the end portion of the boiling part S1 on the side opposite to the side where the condensation part is located, and a sealing member 9 fixed in an inserted state in the through-hole 8 is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor shaft that constitutes a rotor of a rotating electrical machine, and more particularly to a rotor shaft having a boiling cooling function. [Background technology]

[0002] A conventional rotor shaft with a boiling cooling function is described, for example, in Patent Document 1. Patent Document 1 discloses a heat pipe in which a cooling medium is sealed in a sealed hollow hole of a rotor shaft, and a heating heat transfer area and a cooling heat transfer area are provided within the sealed hollow hole. This heat pipe includes a rotor shaft having a sealed hollow hole with one end open, and a lid that closes the open portion of the sealed hollow hole. After the cooling medium is poured into the sealed hollow hole, the lid is friction-welded to the end of the rotor shaft, thereby closing the sealed hollow hole and sealing in the cooling medium.

[0003] The heat pipe absorbs heat generated by the rotor in the heating heat transfer area during operation of the rotating electric machine, vaporizes the cooling liquid medium, and cools the rotor with the heat of vaporization.The heat pipe then releases the heat from the heating heat transfer area to the outside in the cooling heat transfer area, liquefies the cooling liquid medium, and returns the cooling liquid medium to the heating heat transfer area, repeating this cycle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 57-19594 Summary of the Invention [Problem to be solved by the invention]

[0005] In a rotor shaft with boiling cooling function, the internal pressure increases as the temperature inside the heat pipe rises, and this internal pressure is directly applied to the lid, causing large stresses at the lid joint. If a crack occurs at the lid joint, the sealing performance will be impaired, and there is a risk of the working fluid leaking out, resulting in a decrease in cooling function.

[0006] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide a rotor shaft having a structure in which a filling space for a working fluid for boil cooling is sealed with a sealing member, which reduces the load applied to the sealing member and can maintain good sealing properties of the sealing member for a long period of time. [Means for solving the problem]

[0007] The rotor shaft according to the present invention constitutes a rotor for a rotating electric machine and includes a rotor core and rotor shafts connected to both ends of the rotor core, arranged coaxially. The rotor core includes a boiling portion which is a cylindrical space filled with a working fluid, and one of the rotor shafts includes a condensing portion which is a cylindrical space having an inner diameter smaller than that of the boiling portion and communicating with the boiling portion. The rotor shaft is characterized in that a through-hole communicating with the inside and outside of the rotor core is formed at either the tip end of the condensing portion or the end of the boiling portion opposite the condensing portion, and a sealing member is inserted and fixed in the through-hole. [Effects of the Invention]

[0008] The rotor shaft of the present invention has a structure in which a filling space for a working fluid for boiling cooling is sealed with a sealing member, and by reducing the area of ​​the sealing member relative to the filling space, it is possible to reduce the load applied to the sealing member, which also reduces the stress generated at the joint of the sealing member, making it possible to maintain good sealing properties of the sealing member for a long period of time. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a cross-sectional explanatory view showing a first embodiment of a rotor shaft, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Figure 2] FIG. 4 is a cross-sectional view showing a second embodiment of a rotor shaft. [Figure 3] 1A and 1B are cross-sectional views showing a third embodiment of a rotor shaft, FIG. 1C is a cross-sectional view showing a fourth embodiment, FIG. 1D is a cross-sectional view showing a fifth embodiment, and FIG. 1E is a cross-sectional view showing a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment The rotor shaft 1 shown in Fig. 1(A) constitutes the rotor R of a motor M, which is a rotating electrical machine. Note that Fig. 1(A) is a cross-sectional view of the motor with one half of the stator S omitted, and Fig. 1(B) is a cross-sectional view taken along the line AA in Fig. 1(A).

[0011] The motor M comprises a rotor R arranged on the axis and a stator S arranged on the outer periphery of the rotor R, with bearings B, B interposed between the rotor R and the stator S. The rotor R comprises a rotor shaft 1 and a magnet 2 fixed to its outer periphery. The stator S comprises a housing 3 and a coil 4 arranged on its inner periphery.

[0012] The rotor shaft 1 is equipped with a hollow rotor core 11 with magnets 2 arranged on its outer circumferential surface, and coaxial rotor shafts 12 and 13 connected to both ends of the rotor core 11. The rotor shafts 12 and 13 have large diameter portions 12A and 13B on the rotor core 11 side and small diameter portions 12B and 13B on the opposite side from the rotor core 11. One of the rotor shafts 12 shown on the left in Figure 1 is hollow and has a protruding shaft portion 12C at its tip that protrudes along the axis of the rotor core 11.

[0013] The rotor shaft 1 has a boiling portion S1, which is a cylindrical space filled with a working fluid F, inside the rotor core 11. In addition, one rotor shaft 12 of the rotor shaft 1 has an intermediate portion S2, which is a cylindrical space inside the large diameter portion 12A and is in communication with the boiling portion S1, and a condensation portion S3, which is a cylindrical space inside the small diameter portion 12B and is in communication with the boiling portion S1 and the intermediate portion S2. A through hole 8, which communicates with the inside and outside of the rotor core 11, is formed on the axis of the protruding shaft portion 12C.

[0014] As a result, the boiling section S1, the intermediate section S2, the condensation section S3, and the through hole 8 are arranged coaxially and communicate with each other, and are arranged concentrically with respect to the axis C of the rotor shaft 1, as shown in Figure 1(B).

[0015] Furthermore, the rotor shaft 1 is rotatably held by bearings B at the large diameter portions 12A and 13A of both rotor shafts 12 and 13, and a cooler 5 is disposed on the outside of the small diameter portion 12B of one rotor shaft 12, which forms the condenser section S3. The illustrated cooler 5 is a water jacket that includes piping 7 for circulating a cooling liquid 6 and rotatably passes through the small diameter portion 12B of the rotor shaft 12 while ensuring watertightness, and may also include fins for heat dissipation.

[0016] The rotor shaft 1 has a boiling portion S1 with a constant inner diameter R1 along the axis C, and an inner diameter R2a of the intermediate portion S2 at the boundary between the boiling portion S1 and the intermediate portion S2 is smaller than the inner diameter R1 of the boiling portion S1 (R1>R2a). In the illustrated example, the inner diameter R2a of the intermediate portion S2 is approximately one-third of the inner diameter R1 of the boiling portion S1, but is not particularly limited thereto, and an appropriate value can be determined based on the volume of the boiling portion S1, the volume of the working fluid F, etc.

[0017] Further, at the boundary between the intermediate portion S2 and the condensation portion S3 of the rotor shaft 1, the inner diameter R2b of the hollow portion S2 is not less than the inner diameter R3a of the condensation portion S3 (R2b≧R3a), and gradually increases toward the boiling portion S1 side. That is, the intermediate portion S2 has a configuration in which the inner diameter R2a on the boiling portion S1 side is larger than the inner diameter R2b on the condensation portion S3 side (R2b<R2a), and has a tapered structure in which the inner diameter gradually increases from the condensation portion S3 to the boiling portion S1.

[0018] Furthermore, the rotor shaft 1 has a configuration in which the inner diameter of the condensation portion S3 is the same along the direction of the axis C or gradually increases toward the intermediate portion R2 side (the inner diameter R3b of the tip portion is not more than the inner diameter R3a of the intermediate portion S2 side), and the through hole 8 has an inner diameter R8 smaller than the inner diameter R3b of the tip portion of the condensation portion S3. [[ID=******]]

[0019] [[ID=******]] From the above, for the rotor shaft 1, the inner diameter R1 of the boiling portion S1, the inner diameter R2a on the boiling portion S1 side of the intermediate portion S2, the inner diameter R2b on the condensation portion 3 side of the intermediate portion S2, the inner diameter R3a on the intermediate portion S2 side of the condensation portion S3, the inner diameter R3b of the tip portion of the condensation portion S3, and the inner diameter R8 of the through hole 8 have a relationship of R1>R2a>R2b≧R3a≧R3b>R8.

[0020] Furthermore, in the rotor shaft 1, the volume of the working fluid F is smaller than the reference volume calculated based on the difference between the inner diameter R1 of the boiling portion S1 and the inner diameter R2a of the intermediate portion S2 and the axial length of the boiling portion S1. More specifically, the working fluid F is an amount such that the liquid level is below the step between the boiling portion S1 and the intermediate portion S2, is an amount necessary for boiling cooling, and is an amount taking into account the inclination of the vehicle body when the motor M is for vehicle use. As an example, it is an amount that becomes about half or less of the step as shown in the illustrated example.

[0021] The rotor shaft 1 has a structure in which a sealing member 9 fixed in an inserted state is provided in the through hole 8. That is, during the manufacture of the rotor shaft 1, the working fluid F is injected from the through hole 8, and then the sealing member 9 is inserted into the through hole 8 and fixed. [[ID=******]] [[ID=******]]

[0022] [[ID=******]] The sealing member 9 is not limited in material or shape, but in the illustrated example, it is a metal round bar-shaped member, and in the insertion direction into the through-hole 8 shown by the arrow in Figure 1(A), it has a press-fit portion 9A for fixing at its front end and a joint portion 9B for airtightness at its rear end.

[0023] The press-fit portion 9A has a diameter, for example, several μm larger than the inner diameter R8 of the through hole 8, and is press-fit into the through hole 8 to form a tight fit, thereby achieving a fixing function for the sealing member 9. A clearance can be provided between the joint portion 9B and the through hole 8. As will be described in an embodiment below, this joint portion 9B can employ a sealant interposed between it and the through hole 8, allowing the sealing member 9 to achieve an airtight function.

[0024] When the motor M is driven, centrifugal force is applied to the rotor shaft 1 having the above configuration to form a liquid film of the working fluid F on the inner circumferential surface of the boiling section S1, which absorbs heat generated in the rotor R and vaporizes the working fluid F, thereby cooling the rotor R. The rotor shaft 1 then introduces vapor from the boiling section S1 through the intermediate section S2 to the condensing section S3, where it dissipates heat and liquefies the vapor, and the liquefied working fluid F is returned to the boiling section S1 through the intermediate section S2, repeating this cycle.

[0025] At this time, a step is formed on the rotor shaft 1 between the boiling section S1 and the intermediate section S2, so that even if the rotation speed of the rotor R decreases or the condensation section S3 is tilted downward, the step structure prevents the working fluid F in the boiling section S1 from flowing into the intermediate section S2 or the condensation section S3, thereby achieving stable operation.

[0026] The rotor shaft 1 has a structure in which the filling space for the working fluid F is sealed with a sealing member 9, and since the area of ​​the sealing member 9 relative to the filling space is small, it is possible to reduce the load applied to the sealing member 9 and also reduce the stress generated at the joint between the through hole 8 and the sealing member 9, so that the sealing member 9 can maintain good sealing properties for a long period of time.

[0027] Furthermore, since the through hole 8 of the rotor shaft 1 has an inner diameter R8 that is smaller than the inner diameter R3b of the condensation section S3, the load on the sealing member 9 can be reduced according to Pascal's principle, and furthermore, since the sealing member 9 has a press-fit section 9A with a tight fit structure on the front side relative to the internal pressure of the rotor core 11, it is possible to prevent the internal pressure from being directly applied to the joint 9B, and to reliably maintain the airtight function of the joint 9B.

[0028] Furthermore, a rotating electric machine (motor M) equipped with the above-mentioned rotor shaft 1 can efficiently cool the rotor R over a long period of time, since the rotor shaft 1 functions as a heat pipe with a boiling cooling function regardless of the rotation speed, tilt, etc., and the sealing member 9 can maintain good sealing properties.

[0029] 2 and 3(A) to 3(F) are diagrams illustrating second and sixth embodiments of a rotor shaft according to the present invention. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0030] Second Embodiment The motor M and rotor shaft 1 shown in Figure 2 have the same basic configuration as in the first embodiment, and are configured such that a through hole 8 communicating with the inside and outside of the rotor core 11 is formed at the end of the boiling section S1 of the rotor core 11 opposite the condensation section S3, and a sealing member 9 is inserted into and fixed in the through hole 8.

[0031] That is, the rotor shaft 1 has a through hole 8 formed on the axis of the rotor shaft 13 on the other side (the right side in FIG. 2) in the first embodiment. The through hole 8 has an inner diameter R8 that is smaller than the inner diameter R3b of the tip of the condensation section R3. The sealing member 9 has a press-fit portion 9A for fixing at its front end and a joint portion 9B for airtightness at its rear end in the insertion direction into the through hole 8 indicated by the arrow in the figure.

[0032] As in the first embodiment, the rotor shaft 1 described above can reduce the load applied to the sealing member 9 and also reduce the stress generated at the joint between the through hole 8 and the sealing member 9, thereby maintaining good sealing properties of the sealing member 9 for a long period of time. In particular, it is possible to avoid direct application of internal pressure to the joint 9B, thereby reliably maintaining the airtight function of the joint 9B.

[0033] <Third embodiment> The rotor shaft 1, the main parts of which are shown in Figures 3(A) and (B), has the same basic configuration as that of the first embodiment, and has a through hole 8 that directly communicates with the condensation section S3, and is equipped with a sealing member 9 that is inserted and fixed into the through hole 8.

[0034] The sealing member 9 has a press-fit portion 9A that has a tapered shape with the diameter gradually increasing towards the front end, and has a step portion 9C at the boundary with the joint portion 9B that engages with the inner peripheral portion of the through hole 8.

[0035] As shown in the right side of Fig. 3(A), the press-fit portion 9A of the rotor shaft 1 is press-fitted into the through-hole 8, and if the end face of the rotor core (11) on the side opposite the condensation portion has not yet been closed, the joint portion 9B is inserted into the through-hole 8 from inside the rotor core (11) as shown in the left side of Fig. 3(A). As a result, the sealing member 9 is inserted and fixed in place with the stepped portion 9C engaged with the inner peripheral edge of the through-hole 8 as shown in Fig. 3(B).

[0036] The rotor shaft 1 described above can obtain the same effects as those of the first embodiment, and in addition, when the internal pressure of the rotor core (11) rises, the stepped portion 9C engages with the inner peripheral edge of the through hole 8, thereby maintaining the fixed state due to the anchor effect, and the sealing performance of the joint portion 9B can be maintained. Furthermore, in the rotor shaft 1 described above, the press-fit portion 9A of the sealing member 9 protrudes into the condenser portion S3, so that the surface area of ​​the inside of the condenser portion S3 is enlarged as shown by the dotted line in Figure 3(B), thereby realizing improved heat dissipation and cooling effects.

[0037] <Fourth embodiment> The rotor shaft 1, the main part of which is shown in Figure 3(C), has a through hole 8 that directly communicates with the condensation section S3, and is equipped with a sealing member 9 that is inserted and fixed into the through hole 8, and a seal portion 15 that is interposed between a joint portion 9B of the sealing member 9 and the through hole 8. In this case, the rotor shaft 1 has a diameter of the joint portion 9B that is smaller than the inner diameter of the through hole 8, or the inner diameter of the range of the through hole 8 that corresponds to the joint portion 9B is larger.

[0038] As a result, a gap is formed between the through hole 8 and the joint portion 9B of the rotor shaft 1, and a seal portion 15 is interposed in the gap. The gap is, for example, about 0.05 mm. Various sealing materials can be used as the seal portion 15, and for example, brazing material can be used.

[0039] The rotor shaft 1 described above can achieve the same effects as the first embodiment, and can further improve sealing performance by the sealing portion 15. Furthermore, when a brazing material is used in the sealing portion 15, it is easy to control the thickness of the brazing material, which can also contribute to improving quality.

[0040] Fifth Embodiment The rotor shaft 1, the main part of which is shown in FIG. 3(D), has the same basic configuration as that of the first embodiment, and the through hole 8 is formed in the protruding shaft portion 12C that protrudes on the axis of the rotor core (11), and the joint portion 9B of the sealing member 9 has a diameter that is sufficiently larger than the diameter of the press-fit portion A.

[0041] The rotor shaft 1 is provided with a seal portion 16 interposed between the tip end surface of the protruding shaft portion 12C and the joint portion 9B. This seal portion 16 can be made of various sealing materials, but in the illustrated example, it is a welded portion formed on the surface where the protruding shaft portion 12C and the joint portion 9B face each other in the axial direction.

[0042] The rotor shaft 1 described above can achieve the same effects as the first embodiment, and further improves sealing performance by the seal portion 16. Furthermore, since the seal portion 16 is formed by welding the outer periphery of the protruding shaft portion 12C and the joint portion 9B, low-temperature cracking of the press-fit portion 9A can be prevented.

[0043] That is, residual stress occurs in the press-fit portion 9A of the sealing member 9, which is press-fit into the through hole 8, and when welding is performed on this press-fit portion 9A, hydrogen generated during welding is concentrated in the press-fit portion 9A, which can cause cold cracking after welding. In contrast, in the rotor shaft described above, the seal portion 16 is formed by welding the outer circumferential portion of the protruding shaft portion 12C and the joint portion 9B, i.e., the portion away from the press-fit portion 9A, so cold cracking of the press-fit portion 9A can be prevented and the reliability of the sealing function of the sealing member 9 can be improved.

[0044] Sixth Embodiment The rotor shaft 1, the main parts of which are shown in Figures 3(E) and (F), has the same basic configuration as the first embodiment, and is configured to have a plating layer 17 as a seal portion between the through hole 8 and the sealing member 9.

[0045] Although the material of the plating layer 17 is not limited, it is preferably a soft metal plating, for example, zinc plating. The plating layer 17 may be formed on the inner surface of the through hole 8 as shown in Fig. 3(E), or on the outer peripheral surface of the sealing member 9 as shown in Fig. 3(F).

[0046] The rotor shaft 1 having the above configuration can obtain the same effects as the first embodiment, and in addition, when the sealing member 9 is press-fitted into the through hole 8, the plating layer 17 is crushed to fill the gap between the through hole 8 and the sealing member 9, thereby further improving the fixing function and sealing function of the sealing member 9.

[0047] The configuration of the rotor shaft according to the present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope of the gist of the present invention, and it is also possible to combine the configurations of the above-described embodiments. [Explanation of symbols]

[0048] 1 rotor shaft 8 through holes 9 Sealing member 9A Press-fit part 9B Joint 9C Step 11 Rotor core 12,13 Rotor shaft 12C Projected shaft part 15,16 Seal part 17 plating layer M motor (rotating electric machine) S stator S1 Boiling part S3 Condenser R rotor

Claims

1. A rotor shaft constituting a rotor of a rotating electric machine, a rotor core and a rotor shaft connected to both ends of the rotor core, the rotor core being coaxially arranged; the rotor core has a boiling portion therein which is a cylindrical space filled with a working fluid, and one of the rotor shafts has a condensing portion therein which is a cylindrical space having an inner diameter smaller than an inner diameter of the boiling portion and communicating with the boiling portion, A rotor shaft characterized in that a through hole communicating with the inside and outside of the rotor core is formed in either the tip of the condensation section or the end of the boiling section opposite the condensation section, and a sealing member is provided and fixed in a state inserted into the through hole.

2. the through hole has an inner diameter smaller than an inner diameter of the condensation portion, 2. The rotor shaft according to claim 1, wherein the sealing member has a press-fit portion for fixing at a front end side thereof in a direction of insertion into the through hole, and a joint portion for airtightness at a rear end side thereof.

3. 3. The rotor shaft according to claim 2, wherein the press-fit portion of the sealing member has a tapered shape in which the diameter gradually increases toward the front end, and the press-fit portion has a step portion at the boundary with the joint portion that engages with the inner peripheral edge portion of the through hole.

4. 3. The rotor shaft according to claim 2, further comprising a seal portion interposed between the joint portion of the sealing member and the through hole.

5. the through hole is formed in a protruding shaft portion that protrudes on the axis of the rotor core, and the joint portion of the sealing member has a diameter larger than a diameter of the press-fit portion, 3. The rotor shaft according to claim 2, further comprising a seal portion interposed between the tip end surface of the protruding shaft portion and the joint portion.

6. 3. The rotor shaft according to claim 2, further comprising a plating layer between the through hole and the sealing member.

7. A rotating electric machine comprising: a rotor including the rotor shaft according to any one of claims 1 to 6; and a stator corresponding to said rotor.

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