ROTOR

Abstract

Rotor (40), comprising: a shaft (20) with a core element (10) and a resin element (22; 70; 80), wherein the core element (10) is a high-strength element that is cylindrical with an inner hollow section (18), and an outer circumferential surface (14) of the core element (10) is provided with an uneven section formed by a first hole section (12) that penetrates from the outer circumferential surface (14) to the inner hollow section (18); and a rotor core (42) which is attached to a circumference of the resin element (22; 62; 70, 80) characterized by the fact that the resin element (22; 70, 80) covers the outer circumferential surface (14) of the core element (10) while being adhesively attached to the uneven section, and covers an inner circumferential surface (16) of the core element (10) while retaining the inner hollow section (18), the resin element (22) is provided with a second hole section (32) which is connected to the first hole section (12) of the core element (10); and a flow channel for cooling oil, extending from the inner hollow section (18) of the core element (10) to the outer circumferential surface (14) of the resin element (22), is formed through the first hole section (12) and the second hole section (32).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to a rotor with a shaft having an outer circumferential section for which resin is used. 2. Description of the state of the art

[0002] In a motor rotor (rotator), a shaft is generally formed from a metal or similar high-strength material. However, motor rotors are also known in which resin is used to bond the shaft and rotor core together.

[0003] Japanese patent application JP 2000-125 523 A describes how a rotor is formed by installing a rod-shaped metal, serving as both the core of a shaft and the rotor core, in a mold and injecting resin into the mold. The resin has an uneven outer circumferential surface. The resin and the rotor core are coupled together, with the outer circumferential surface of the resin and a correspondingly shaped inner circumferential surface of the rotor core interlocking.

[0004] Japanese patent application JP 2000-166 194 A describes a method for manufacturing a rotor in which a shaft is inserted into a shaft hole of a rotor core and resin is injected into a gap between them.

[0005] A rotor for high-speed electric machines and machines with high dynamics is the subject of DE 10 2007 006 986 B3. In this design, a base body made of fiber-reinforced plastic, configured as a hollow shaft, is positioned between bearing seats. At least one laminated core, magnets, and a bandage are arranged radially on the base body. The base body has a positive-locking contour corresponding to the laminated cores in the area where they are arranged, and cooling channels are provided between the base body and the laminated core. Radial cooling air bores are arranged in the base body, connecting the cavity of the base body to the cooling channels.From the generic patent DE 32 43 212 A1, a small electric motor with an armature is known, the shaft, laminated core, and commutator of which are fixed to one another in a single-piece plastic part that also insulates the laminated core from the windings. At least at one end of the shaft, a recess with a cross-section deviating from a circular shape is provided into this recess, into which another shaft with a corresponding cross-section can engage. For further information on the prior art, reference is made to Habenicht, Gerd: Kleben metallicer Werkstoffe. In: Kleben: Grundlagen, Technologien,anwendungen. 6th, updated edition. Berlin: Springer, 2009. Title page + imprint + table of contents, pp. 625–643. - ISBN 978-3-540-85264-3, as well as to WO 2014 / 068 041 A1. SUMMARY OF THE INVENTION

[0006] If the shaft is made of metal, the rotor's rotational efficiency decreases due to the increased weight. Conversely, if the shaft is made of resin, its strength is insufficient, although weight reduction can be achieved. Increased shaft strength is particularly important when the motor's output or power is high.

[0007] In the aforementioned Japanese patent applications JP 2000-125 523 A and JP 2000-166 194 A, the shaft and rotor core are joined by injecting resin. However, these technologies do not aim to reduce the weight of the shaft, but merely attempt to improve the accuracy or stability of the connection between the shaft and rotor core and to suppress vibrations, etc., of the rotor. Furthermore, the process of ensuring the adhesive strength between the metal and the resin forming the shaft is not mentioned.

[0008] If the outer circumferential section of the shaft is made of resin, an improvement in rotational properties can be expected due to a reduction in shaft weight. However, if the transmitted torque becomes high, problems may arise with the rotor because the bond strength at the interface between the resin and an inner circumferential section of the shaft is insufficient.

[0009] According to the invention, a rotor is proposed which increases the adhesive strength between resin and an inner circumferential section of a shaft when this resin is used for an outer circumferential section of the shaft.

[0010] One aspect of the invention is a rotor with a shaft and a rotor core, which are constructed as follows. The shaft includes a core element and a resin element. The core element is a high-strength element that is cylindrical with an inner hollow section. An outer circumferential surface of the core element is provided with an uneven section formed by a first hole section that extends from the outer circumferential surface to the inner hollow section. The rotor core is attached to a circumference of the resin element. The resin element covers the outer circumferential surface of the core element while being adhesively attached to the uneven section, and covers an inner circumferential surface of the core element while retaining the inner hollow section. The resin element is further provided with a second hole section that communicates with the first hole section of the core element.A flow channel for cooling oil, extending from the inner hollow section of the core element to the outer circumferential surface of the resin element, is formed by the first hole section and the second hole section.

[0011] In this aspect of the invention, the uneven section can be formed by plastic deformation or chemical processing. Plastic deformation can be achieved by one of the following processing methods, namely (i) shot blasting, (ii) semi-stamping, and (iii) embossing. Furthermore, chemical processing can be etching.

[0012] In this aspect of the invention, a plurality of glass fibers can be incorporated into the resin element. Furthermore, a plurality of metals can be incorporated into the resin element.

[0013] According to the invention, the rotor can achieve a reduced weight of the rotor shaft and high strength, thereby increasing the output power and torque of a motor using this rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features and advantages as well as the technical and economic significance of exemplary embodiments of the invention are described below with reference to the accompanying drawing, in which the same reference numerals denote the same elements; here shown: Fig. 1 a perspective view of a core element of a shaft belonging to a rotor according to the first embodiment of the invention; Fig. 2 a perspective view of the wave with the core element covered by a resin element; Fig. 3 a view of an end face with a central axis of the shaft; Fig. 4 a view of an end face of the wave along a plane IV-IV of Fig. 3; Fig. 5 a view of an end face of the wave along a plane VV of Fig. 3; Fig. 6 a view of an end face with a central axis of the rotor, wherein the shaft and a rotor core belonging to the rotor are coupled together; Fig. 7 a view of an end surface with a central axis of a shaft belonging to a rotor according to the second embodiment of the invention; Fig. 8 a view of an end face of the wave along a plane VIII-VIII of Fig. 7; Fig. 9 a view of an end face of the wave along a plane IX-IX of Fig. 7; Fig. 10 a schematic representation of a glass fiber-containing resin element included in a rotor according to the third embodiment of the invention; and Fig. 11 a schematic representation of a metal filler resin element contained in the rotor. DETAILED DESCRIPTION OF EXECUTION FORMS

[0015] Rotors according to the embodiments of the invention are described below with reference to the drawings. For better understanding, specific aspects are presented in the description. These specific aspects illustrate exemplary embodiments, and the invention can be implemented using various other embodiments.

[0016] The rotor according to the first embodiment is referred to as follows: Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 described. Fig. Figure 1 is a perspective view of a core element 10 of a rotor shaft according to the first embodiment. The core element 10 is formed in the form of a round cylinder. A plurality of first hole sections 12, forming an uneven section on a wall surface of the core element 10, are formed near a central section of the core element 10 in an axial direction. This area is where a rotor core will be attached, as described later, and a certain degree of adhesion is required between the core element 10 and a resin element arranged around its circumference. The first hole sections 12 are through holes extending from an outer circumferential surface 14 of the core element 10 to an inner circumferential surface 16 of the same. Thus, the circumference of the core element 10 and an inner hollow section 18 of the core element 10 are in communication with each other.In the illustrated example, each of the first hole sections 12 essentially has the shape of a square opening. The opening area of ​​each of the first hole sections 12 is sufficiently smaller than the area of ​​the outer circumferential surface 14 of the core element 10. The first hole sections 12 are formed regularly along the entire circumference of the outer circumferential surface 14 of the core element 10. However, it should be noted that the first hole sections 12 are bordered by the inner circumferential surface 16 on the other side. Fig. 1 are not shown for the sake of simplifying the schematic representation. That is, the first hole sections 12 are provided over the outer circumferential surface 14 in such a way that an essentially constant surface density is ensured, instead of being concentrated in a specific area. Although in the example of Fig. 1. If no first hole sections 12 are provided near the two ends of the core element 10, an attempt can be made to reduce the weight of the core element 10 by forming first hole sections 12 near the two ends of the core element 10.

[0017] The core element 10 is an element that ensures the shaft's strength and consists of a solid material with a higher strength than resin. Various metals, such as steel (including high-strength steel, or HTSS), aluminum alloys, and the like, can be used as examples of this solid material. A non-metallic solid material, such as carbon fiber reinforced plastic (CFRP), can also be used as core element 10. Core element 10 can be manufactured using various production methods.For example, when metal is used as a solid element, it is possible to mention (i) an aspect in which the core element 10 is produced by providing a metal element in the form of a circular cylinder with the first hole sections 12, (ii) an aspect in which the core element 10 is formed by punching a metal plate to provide the first hole sections 12 through it, and then rounding and welding the metal plate, (iii) an aspect in which the core element 10 is formed by pouring molten metal into a mold, and the like.

[0018] Fig. Figure 2 is a schematic perspective view of the shaft 20 according to the embodiment. The shaft 20 consists of the core element 10 and a resin element 22 that covers one circumference of the core element. The shaft 20 is formed by a molding process, i.e., by inserting the core element 10 into a mold, injecting resin into the mold, and allowing the resin to cure.

[0019] The resin element 22 is essentially formed in the form of a circular cylinder concentric with the core element 10, but the diameter of the circular cylinder varies along the axial direction. Specifically, the drawing shows a bearing sliding section 24, a rotor core mounting section 26, a mounting section 28, and a bearing sliding section 30 extending from an upper end to a lower end. The bearing sliding sections 24 and 30 at both ends are areas for rotatably supporting both ends of the shaft 20 by bearings and are formed with a smaller diameter, i.e., a smaller thickness, than the other areas. The rotor core mounting section 26 is an area in which the rotor core, formed from electromagnetic steel sheets or the like, is installed, and the diameter of the rotor core mounting section 26 is larger than that of the bearing sliding sections 24 and 30.The fastening section 28 is an area that serves as a stop to prevent the rotor core from moving downwards in the axial direction, and the diameter of the fastening section 28 is set larger than that of any other section.

[0020] For example, thermosetting or thermoset resin is used as the resin forming resin element 22. The rotor generates heat through the flow of an inductive current during its rotation. Therefore, the heat resistance of the rotor is increased by using a thermosetting resin, which exhibits high heat resistance. Various resins such as phenolic resin, epoxy resin, melamine resin, and the like can be used as thermosetting resins.

[0021] Furthermore, the resin element 22 can also assume other shapes than the one shown in the drawing. For example, a structure for attaching a rotary encoder rotor for measuring the rotation of the shaft can be formed near a boundary between the bearing sliding section 24 and the rotor core mounting section 26. The rotor core mounting section 26 can be provided with locating grooves or the like to prevent slippage relative to the rotor core in the circumferential direction. This will be described later with reference to Fig. 5 described. Furthermore, as described below, the rotor core mounting section 26 can also be provided with through holes that are connected to the first hole sections 12 of the core element 10. In resin molding, even a complex or elaborate shape can be formed in one operation, thus reducing manufacturing costs.

[0022] Next, the construction of wave 20 will be described using the Fig. 3, Fig. 4 to Fig. 5 described in detail. Fig. 3 is a view of an end face of the in Fig. 2 shown shaft 20 along a plane extending beyond an axial center of the cylinder. Fig. 4 is a view of an end face of wave 20 along a plane IV-IV of Fig. 3, and Fig. 5 is a view of an end face of wave 20 along a plane VV of Fig. 3.

[0023] As in Fig. As shown in Figure 3, the resin element 22 covers both the end faces of the core element 10 in the axial direction and the inner circumferential surface 16 of the core element 10, as well as the outer circumferential surface 14 of the core element 10. The majority of the first hole sections 12 of the core element 10 are in Fig. Figure 3 shows eight representative examples (each identified by reference numerals 12a to 12h). Of these hole sections, the interiors of the first hole sections 12a, 12e, located near the sliding bearing section 24, and of the first hole sections 12d, 12h, located at the fastening section 28, are filled with resin. Furthermore, the side of the outer circumferential surface 14 of the core element 10 and the side of the inner circumferential surface 16 of the same are connected (see also Fig. 4) Thus, the resin element 22 is bonded to the core element 10 at the first hole sections 12, and the degree of adhesion between the resin element 22 and the core element 10 is also increased in the parts other than the first hole sections 12. It should be noted that adhesive bonding means that at least a portion of the resin element 22 is shaped to correspond to the uneven section of the core element 10 and is made to adhere to it in close contact. The adhesion can be achieved by one of the following bonding methods: mechanical bonding (bonding based on an anchoring effect), bonding based on a physical interaction (bonding based on a van der Waals force), bonding based on a chemical interaction (chemical bonding), and the like.Furthermore, the resin that has penetrated the first hole sections 12a, 12e, 12d, 12h physically prevents the resin element 22 and the core element 10 from moving in the circumferential direction, so that a large torque can be transmitted between the resin element 22 and the core element 10.

[0024] On the other hand, the first hole sections 12b, 12c, 12f, 12g on the rotor core mounting section 26 are not filled with resin, and second hole sections 32a, 32b, 32c, 32d (which can be collectively referred to as second hole sections 32), which are connected to these first hole sections 12b, 12c, 12f, 12g, are formed by the resin element 22 inside and outside the rotor core mounting section 26. That is, through-holes are formed in the shaft 20 by these second hole sections 32a, 32b, 32c, 32d, leading from the inner hollow section 18 to an outer circumferential side of the resin element 22. These through-holes can be used as flow channels for cooling oil, as described later.

[0025] Furthermore, in the Fig. In the example shown, all four first hole sections 12b, 12c, 12f, 12g, which are provided near the rotor core attachment section 26, are designed as through holes. However, one or some of these four hole sections can be filled with resin, as with the first hole sections 12a, 12d, 12e, 12h. This increases the degree of adhesion between the resin element 22 and the core element 10 near the rotor core attachment section 26. In particular, the area near the rotor core attachment section 26 is a part that receives a large torque from the rotor core and must have an adhesive strength high enough to withstand the torque. Considering the need for flow channels for cooling oil and the degree of adhesion between the resin element 22 and the core element 10, it can be determined how many of the majority of the first hole sections 12 should be filled with resin.

[0026] Regarding the end surface in Fig. 5. Fit grooves 34a, 34b are formed in an outer circumferential surface of the resin element 22. Although in Fig. Not shown in Figure 2, these locating grooves 34a, 34b extend axially near the rotor core mounting section 26. The locating grooves 34a, 34b are located on corresponding protruding parts of the rotor core, which is attached to the outer circumference of the shaft 20, and thus prevent circumferential movement. This allows a large torque to be transmitted between the rotor core and the resin element 22. In the example of Fig. 5. The shaft 20 and the resin element 22 are prevented from moving circumferentially by the fitting grooves 34a, 34b. However, other structures can also be used. For example, circumferential movement can be physically prevented by forming the cross-section of the outer circumferential surface of the resin element 22 in the form of a polygon such as a hexagon, an octagon, or the like, and by forming the cross-section of the inner circumferential surface of the rotor core in a shape corresponding to this polygon.

[0027] Fig. Figure 6 shows a rotor 40 with a rotor core 42 mounted on the shaft 20. The rotor core 42 is a cylindrical element formed by stacking multiple ring-shaped stamped electromagnetic steel sheets. The rotor core 42 is mounted on the shaft 20, and a bottom surface 42a of the rotor core 42 is held in adhesive contact with a top surface of the mounting section 28.

[0028] The rotor core 42 is mounted onto the shaft 20, for example, by means of a shaft hole enlarged by heating, i.e., by "shrink-fitting" or "hot-fitting." The heating takes place within a continuous temperature range of the resin element 22. In this case, after the temperature of the rotor core 42 has dropped, the shaft 20 and the rotor core 42 are securely joined. Alternatively, the rotor 40 can be formed by pressing the shaft 20 into the rotor core 42. This pressing is performed with a force that does not damage the resin element 22 of the shaft 20. If, for example, the resin element 22 is made of thermosetting or thermosetting resin, it is also conceivable to assume a configuration in which the resin element 22 can deform to a certain degree, instead of being completely cured before the end of the pressing process and then being fully cured by heating afterward.Furthermore, a narrow gap can be provided between the shaft 20 and the rotor core 42 to facilitate assembly. In this case, it is conceivable, for example, to assume an aspect in which the shaft 20 and the rotor core 42 are fastened together by strongly compressing the rotor core 42 from above, an aspect in which the shaft 20 and the rotor core 42 are fastened together by injecting an adhesive into the gap between them, and the like.

[0029] After the shaft 20 has been inserted into the rotor core 42, the rotor core 42 is secured on its upper surface 42b as necessary. This securing is achieved, for example, by attaching a metal or resin fixing element to the resin element 22 on the upper surface 42b of the rotor core 42 and holding the upper surface 42b in place using this fixing element. To carry out this securing, the resin element 22 can be shaped so that the fixing element is attached to it. For example, if an end plate is used as a fastening or fixing element, one aspect can be mentioned in which a groove for receiving the end plate is formed in the resin element 22. Furthermore, it is also conceivable to assume an aspect in which a structure for attaching a bolt or screw to secure the fixing element is formed in the resin element 22.In the event that a large force is required to attach the fixing element, the fixing element can be attached to the core element 10.

[0030] Next, a magnet is inserted into the rotor core 42. The rotor 40 is then installed in a stator, thus forming a motor.

[0031] The operation of the rotor 40 in the motor will now be briefly described. A magnetic pole of the rotor core 42 and a magnetic pole of the stator exert a magnetic force on each other, and the rotor 40 rotates circumferentially, with a central axis of the shaft 20 serving as the axis of rotation. At this point, a torque is transmitted from the rotor core 42 to the resin element 22 of the shaft 20. The rotor core 42 is attached to the locating grooves 34a, 34b of the resin element 22, thus enabling the torque transmission. A torque is also transmitted from the resin element 22 to the core element 10. The first perforated sections 12 of the core element 10 are filled with the resin forming the resin element 22, and the torque can therefore be transmitted from the resin element 22 to the core element 10.Incidentally, the torque transmission path in a regeneration process and the torque transmission path in a power running process are reversed, and the difference lies in the fact that the direction of rotation in the regeneration process and the direction of rotation in the power running process are opposite to each other. However, the rotor 40 operates in essentially the same way.

[0032] The transmitted torque is carried outwards from a tip end of the shaft 20 by a gear or similar device. The gear provided for this purpose can be attached to the resin element 22 or to the core element 10. In the case where the gear is attached to the core element 10, the core element 10, as a fixed element, assumes a large part of the torque transmission in the axial direction, thus enabling the transmission of a high torque.

[0033] During rotation, an eddy current flows through the rotor core 42, causing the rotor core 42 to generate heat and its temperature to rise. Cooling oil is used to cool this rotor core 42. The cooling oil flows from the inner hollow section 18 of the shaft 20 and reaches the outer circumferential surface of the shaft 20 through through-holes in the wall surface. These through-holes are formed by the connection between the first hole sections 12 of the core element 10 and the second hole sections 32 of the resin element 22. Cooling channels are formed through the rotor core 42 for introducing this cooling oil into the rotor core 42 and for draining the cooling oil from its outer circumferential side. The cooling oil cools the rotor 40 as it flows through these cooling channels, since a centrifugal force is exerted on the rotor 40.

[0034] In this rotor 40, the shaft 20 is formed by the use of the resin element 22. Therefore, the rotor 40 is lighter than in the case where the shaft 20 is formed solely from a solid element such as metal or the like. Consequently, the rotor 40 is advantageous because its rolling resistance decreases and its rotational efficiency increases. The degree of weight reduction of the shaft 20 can be adjusted, but its weight can be reduced to, for example, approximately 30%, 40%, or 50%. Generally, the resin element 22 has a lower strength than metal or the like. However, the core element 10 reinforces the strength of the resin element 22, so that the shaft 20 as a whole can transmit a high torque. Therefore, the rotor 40 can also be used, for example, in a motor to power an electric vehicle or the like.

[0035] Furthermore, in shaft 20, the surfaces of the bearing sliding sections 24, 30 are formed from resin, as in Fig. Figure 2 illustrates this. This ensures uniform rotation with respect to the bearings and prevents torque loss. Furthermore, by utilizing the self-lubricating properties of the resin at the bearing sliding sections 24 and 30, the shaft 20 can also be supported without the use of bearings. In this case, the targeted application of lubricating oil can be used to increase smoothness and suppress heat generation. Additionally, the core element 10 can be exposed as a solid element at the bearing sliding sections 24 and 30 if the shaft needs to be sufficiently rigid to rotate at high speed.

[0036] In rotor 40, the insulation properties in the rotor core 42 can also be easily ensured by using the resin element 22. The rotor core 42 is formed as described above by stamping the electromagnetic steel sheets, which may result in burrs being formed at the end sections of the rotor core 42. As described in Fig. As shown in Figure 6, an inner circumferential surface 42c of the rotor core 42c is in contact with the thick resin element 22 and does not come into contact with the core element 10 even if the surface of the resin element 22 is damaged by the burrs. Accordingly, a short circuit between the layers of the electromagnetic steel sheets of the rotor core 42 does not occur, and a deterioration of the electromagnetic properties of the rotor core 42 due to the influence of iron losses or the like can be prevented.

[0037] In the preceding description, the core element 10 is formed in the form of a round cylinder. However, the core element 10 can also have the shape of a cylinder other than a round one. For example, it is possible to mention a cylinder whose cross-sectional shape is defined by the curve of an imprecise circle, such as an ellipse or the like, a polygonal cylinder whose cross-sectional shape is a polygon, and so on. Furthermore, the first hole sections 12 are shown as an example of the uneven section on the outer circumferential surface 14 of the core element 10. These first hole sections 12 form the uneven section whose outer circumferential surface assumes an uneven shape that deviates locally from a circle.As such an uneven section, it is possible, in addition to the first hole sections 12, to mention an aspect in which a projection is provided and an aspect in which a recess is provided, as described in the second embodiment. However, the uneven section is not limited to such a local shape. At least part of the cross-section of the outer circumferential surface can assume a shape that deviates from a smooth circle. For example, an elliptical cylinder or a polygonal cylinder has an uneven outer circumferential surface that deviates from a circle over a wide area and forms the uneven section.

[0038] Furthermore, in the preceding description, the inner circumferential surface 16 of the core element 10 in shaft 20 is also covered with the resin element 22, as in the Fig. 3, Fig. 4 to Fig. Figure 5 illustrates this. However, the resin generally has a lower thermal conductivity than metal or similar materials, so the cooling capacity of the core element 10 covered by the resin element 22 decreases. It is also conceivable to consider a configuration in which part or all of the inner circumferential surface 16 of the core element 10 is not covered by the resin element 22. In this case, the bond strength between the core element 10 and the resin element 22 decreases, so the area covered by the resin element 22 can be reduced to a level sufficient to transmit the required torque. Similarly, it is conceivable to consider a configuration in which part or all of each of the two ends of the core element 10 is not covered by the resin element 22 in the axial direction.

[0039] Now, according to the second embodiment, the rotor is described with reference to the Fig. 7, Fig. 8 to Fig. 9 described. Fig. 7 is a view of an end surface accordingly Fig. 3. Furthermore, Fig. 8 a view of an end face along a plane VIII-VIII of Fig. 7 and Fig. 9 a view of an end face along a plane IX-IX of Fig. 7. The Fig. 8 and Fig. 9 correspond to the Fig. 4 and Fig. 5. The following description focuses on the difference from the first embodiment.

[0040] A wave 50 according to the one in the Fig. 7, Fig. 8 to Fig. The second embodiment shown in Figure 9 is formed from a core element 52 and a resin element 62. The core element 52 is in the form of a circular cylinder, and a plurality of recessed sections 60a to 60h (which can be collectively referred to as recessed sections 60), forming an uneven section, are formed in an outer circumferential surface 54 of the core element 52. The recessed sections 60 do not penetrate to an inner circumferential surface 56, and an inner hollow section 58 of the core element 52 is in a state in which only its two ends are open in the axial direction.

[0041] The outer circumferential surface 54 of the core element 52 is subjected to shot peening. This means that the fatigue strength of the outer circumferential surface 54 is increased by applying a compressive load to the outer circumferential surface 54 through high-speed collisions of a group of small metal particles with it, thereby reducing the tensile stress of the outer circumferential surface 54 and its residual stress. Thus, as in Fig. Figure 7 schematically shows a plurality of tiny irregularities on the outer circumferential surface 54, and the outer circumferential surface 54 has a rough surface. This roughening is an aspect of the uneven section that is plastically formed by the abrasive blasting.

[0042] The resin element 62 is integrally formed around the core element 52. The resin element 62 covers both the ends of the core element 52 and its inner circumferential surface 56, as well as its outer circumferential surface 54. The resin element 62 is formed in a projecting shape at the recessed sections 60 to penetrate into the recessed sections 60. Furthermore, the resin element 62 is also formed in a shape corresponding to the unevenness created on the outer circumferential surface 54 by shot blasting, and the outer circumferential surface 54 is in adhesive contact with the resin element 62. The shape of the outer circumference of the resin element 62 is the same as in the first embodiment. As in Fig. Figure 9 shows that on an outer circumferential surface of the resin element 62 fitting grooves 64a and 64b are formed, into which a rotor core is inserted.

[0043] In the second embodiment, unlike the first embodiment, no perforated sections are formed by the core element 52, and the recessed sections 60 are formed on the outer circumferential surface 54. Therefore, the resin element 62 is simply connected to the side of the inner circumferential surface 56 of the core element 52 only by end sections of the resin element 62 in the axial direction. In this respect, the degree of adhesion to the core element 52 is relatively low. However, the resin that has penetrated the recessed sections 60 physically prevents the core element 52 and the resin element 62 from moving circumferentially, so that a large torque can be transmitted.

[0044] Furthermore, the resin element 62 is in adhesive contact with the irregularities that form on the outer circumferential surface 54 of the core element 52 as a result of the shot blasting. This uneven or irregular shape has a larger contact area than a flat shape, so that the degree of adhesion between the resin element 62 and the core element 52 is significantly increased. Moreover, the irregularities resulting from this shot blasting also prevent the core element 52 and the resin element 62 from moving circumferentially. Accordingly, a high torque can be transmitted in both the second and the first embodiments.

[0045] Incidentally, if the required adhesive strength can only be ensured by the recessed sections 60, it is not necessary to create the irregularities through shot blasting. Conversely, if the required adhesive strength can only be ensured by the irregularities occurring during shot blasting, it is not necessary to create the recessed sections 60. The creation of the irregularities through shot blasting also applies to the first embodiment. Furthermore, the first and second embodiments can be combined to provide both the first hole sections 12 and the recessed sections 60.

[0046] In the preceding description, shot peening was mentioned as an example of abrasive blasting. Abrasive blasting is used to modify a surface by colliding a projection material with the surface being treated at high speed. The projection material is typically a solid metal, a polishing compound, or the like. Sandblasting, carried out in a work box called a sandblaster, and wet blasting, performed with a polishing compound mixed with water, are also known. Additionally, the surface can be modified using a cavitation blasting process, in which bubbles in high-speed flowing water are used as the projection material.The increase in fatigue strength of the outer circumferential surface, the formation of unevenness through rough machining of the surface and an increase in surface area are achieved by carrying out shot blasting.

[0047] The rotor according to the third embodiment is described with reference to the Fig. 10 and Fig. 11 described. The third embodiment is a specific shape that can additionally be introduced into the resin element 22 of the first embodiment and the resin element 62 of the second embodiment.

[0048] Fig. Figure 10 is a schematic view representing part of a resin element 70. A plurality of glass fibers 72 are incorporated into the resin element 70 as fillers. In general, the glass fibers exhibit higher strength than resin and high tensile strength, especially in the fiber direction. Thus, when a load is applied in a direction indicated by an arrow 74 in the drawing, the resin element 70 can be protected from deformation and destruction. This allows a greater torque to be transmitted than if the glass fibers 72 were not added.

[0049] In general, the glass fibers 72 tend to align along the flow direction of the resin. Accordingly, when forming the resin element 70, molten resin can be injected along the direction in which the resin element 70 is to be reinforced, for example, circumferentially or axially. Alternatively, molten resin can be stirred and then injected so that the glass fibers 72 are randomly oriented if the resin element 70 is to be reinforced in multiple directions. The glass fibers 72 are exemplary reinforcing fibers. Other reinforcing fibers, such as carbon fibers or the like, can be added as fillers instead of or in combination with the glass fibers 72. The fiber content can be determined according to the required strength.

[0050] Fig. Figure 11 is a schematic view representing part of a resin element 80. Elongated metals 82 with high thermal radiation are incorporated into the resin element 80 as fillers. The metals exhibit high thermal conductivity, so the resin element 80 has a higher thermal conductivity than if it were made of resin alone. In particular, because the metals 82 are elongated, the surface area is larger and the thermal conductivity higher than if a metal block of the same volume or weight were added. Furthermore, the thermal conductivity is improved, especially in the longitudinal direction. This prevents the temperature of the rotor (magnet) from rising and thus avoids a deterioration in the rotor's performance.

[0051] As in the one relating to Fig. In accordance with the aspect described in section 10, the elongated metals 82 tend to align themselves with the flow direction of the molten resin, and it is advisable to allow the resin to flow in a direction that is desired to improve thermal conductivity, for example, in a direction perpendicular to the outer circumferential surface. However, it should be noted that orientation in random directions is also acceptable if controlling the resin flow is difficult. Furthermore, isotropy can be ensured by using minute metal blocks as filler instead of the elongated metals 82.

[0052] Furthermore, the fillers generally do not appear on the surface of the mixed resin, but tend to collect within the resin. Accordingly, it is assumed that both in the Fig. The resin element 70 shown in 10, as well as the one in Fig. The resin element 80 shown in Figure 11 has only a minor influence on friction in the bearing areas. Furthermore, it is assumed that the resin element 80 in Figure 11 has a minimal influence on friction in the bearing areas. Fig. 11. A short circuit between the electromagnetic steel sheets of the rotor core is unlikely in the resin element 80 shown.

Claims

Rotor (40), comprising: a shaft (20) with a core element (10) and a resin element (22; 70; 80), wherein the core element (10) is a high-strength element that is cylindrical with an inner hollow section (18), and an outer circumferential surface (14) of the core element (10) is provided with an uneven section formed by a first hole section (12) that penetrates from the outer circumferential surface (14) to the inner hollow section (18); and a rotor core (42) that is attached to a circumference of the resin element (22; 62; 70, 80), characterized in that the resin element (22;70, 80) covers the outer circumferential surface (14) of the core element (10) while being adhesively attached to the uneven section, and covers an inner circumferential surface (16) of the core element (10) while retaining the inner hollow section (18); the resin element (22) is provided with a second hole section (32) which is connected to the first hole section (12) of the core element (10); and a flow channel for cooling oil, extending from the inner hollow section (18) of the core element (10) to the outer circumferential surface (14) of the resin element (22), is formed through the first hole section (12) and the second hole section (32). Rotor (40) according to claim 1, wherein the uneven section is formed by plastic deformation or chemical processing. Rotor (40) according to claim 2, wherein the plastic deformation is carried out as one of the following processing methods, namely (i) shot peening, (ii) semi-stamping and (iii) embossing. Rotor (40) according to claim 2, wherein the chemical treatment is an etching treatment. Rotor (40) according to claim 1, wherein a plurality of glass fibers (72) are incorporated into the resin element (70). Rotor (40) according to claim 1, wherein a plurality of metals (82) are incorporated into the resin element (80).

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