JP7755982B2 - Rotor, rotating electric machine and drive device - Google Patents

Description

The present invention relates to a rotor, a rotating electric machine, and a drive unit.

IPM (Interior Permanent Magnet) rotors, in which magnets are embedded inside the rotor core, have been known for some time. Patent Document 1 discloses a method of using a foamed resin sheet to secure magnets in the magnet holes of the rotor core.

Japanese Patent Application Laid-Open No. 2006-311782

The load applied to the magnets when the rotor rotates varies depending on the magnet's position and orientation relative to the rotor core. Therefore, magnets assembled in different positions and orientations relative to the rotor core are subjected to different loads. On the other hand, in conventional rotors, all magnets are fixed with the same foam sheet regardless of their position and orientation. In conventional structures, the same foam sheet is used for all magnets, so there is a risk that a foam sheet with a holding force that far exceeds the required strength may be selected in some locations. Furthermore, this could result in higher rotor costs overall.

One of the objectives of the present invention is to provide a rotor, rotating electric machine, and drive unit that can properly hold magnets.

One embodiment of the rotor of the present invention comprises a rotor core having a first magnet hole and a second magnet hole extending axially about a central axis, a first magnet disposed in the first magnet hole, a second magnet disposed in the second magnet hole, a first foam sheet disposed between the inner wall of the first magnet hole and the first magnet, and a second foam sheet disposed between the inner wall of the second magnet hole and the second magnet. The magnetic holding force of the first foam sheet and the magnetic holding force of the second foam sheet are different from each other.

One aspect of the rotating electric machine of the present invention comprises the rotor described above and a stator disposed radially outward of the rotor.

One embodiment of the drive device of the present invention comprises the aforementioned rotating electric machine and a transmission device connected to the rotor.

One aspect of the present invention provides a rotor, rotating electric machine, and drive unit that can properly hold magnets.

FIG. 1 is a schematic diagram illustrating a drive device according to an embodiment. FIG. 2 is a plan view of the rotor of the embodiment as viewed from the axial direction. FIG. 3 is a plan view showing a portion of a rotor according to an embodiment. FIG. 4 is a perspective view showing a foam sheet. FIG. 5 is a side view showing a foam sheet. FIG. 6 is a perspective view of a first foam sheet that can be used in one embodiment. FIG. 7 is a perspective view of a second foam sheet that can be used in one embodiment. FIG. 8 is a plan view showing a part of the rotor of the first modified example. FIG. 9 is a plan view showing a part of the rotor of the second modification.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the vertical direction will be defined based on the positional relationship when the drive device of the embodiment is mounted on a vehicle positioned on a horizontal road surface. In the drawings, an XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. In the XYZ coordinate system, the Z-axis direction is the vertical direction.

The central axis J shown in the figures is an imaginary axis. The central axis J extends in the Y-axis direction, which is perpendicular to the vertical direction. In the following explanation, unless otherwise specified, the direction parallel to the central axis J will be referred to simply as the "axial direction," the radial direction centered on the central axis J will be referred to simply as the "radial direction," and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be referred to simply as the "circumferential direction."

The arrow θ shown in the figures indicates the circumferential direction. In the following description, the side of the circumferential direction that moves counterclockwise around the central axis J when viewed from the left, i.e., the side toward which the arrow θ points (+θ side), will be referred to as "one circumferential side," and the side of the circumferential direction that moves clockwise around the central axis J when viewed from the left, i.e., the side opposite to the side toward which the arrow θ points (-θ side), will be referred to as "the other circumferential side."

<Drive unit>
1, the drive device 100 of this embodiment includes a rotating electric machine 10, a transmission device 60, and a housing 6. The drive device 100 is mounted on a vehicle powered by a motor, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as the power source thereof.

<Transmission device>
The transmission device 60 is connected to the rotor 30 of the rotating electric machine 10. The transmission device 60 transmits the rotation of the rotor 30 to an axle 64 of the vehicle. The transmission device 60 has a reduction gear 62 connected to the rotor 30, and a differential gear 63 connected to the reduction gear 62. The differential gear 63 has a ring gear 63a.

<Housing>
The housing 6 has a gear housing 61 that houses the transmission device 60 and a motor housing 65 that houses the rotating electrical machine 10. Oil O accumulates in a lower region of the gear housing 61. The oil O circulates within a refrigerant flow path 90. The oil O is used as a refrigerant that cools the rotating electrical machine 10. The oil O is also used as a lubricant for the reduction gear 62 and the differential gear 63.

The housing 6 is provided with a refrigerant flow path 90 through which oil O circulates. The refrigerant flow path 90 is provided across the interior of the motor housing 65 and the interior of the gear housing 61. The refrigerant flow path 90 is a path through which oil O stored in the gear housing 61 is supplied to the rotating electrical machine 10 and then returned to the gear housing 61. The refrigerant flow path 90 is provided with a pump 71 that pressurizes the oil O, a cooler 72 that cools the oil O, and a refrigerant supply unit 50 that supplies the oil O to the rotating electrical machine 10.

The oil O stored in the gear housing 61 is pumped up by the pump 71 and flows into the cooler 72. The oil O that flows into the cooler 72 is cooled therein and then flows into the refrigerant supply unit 50. A portion of the oil O that flows into the refrigerant supply unit 50 is supplied to the stator 40. Another portion of the oil O that flows into the refrigerant supply unit 50 flows into the shaft 31. A portion of the oil O that flows into the shaft 31 is scattered onto the stator 40 by the centrifugal force of the shaft 31. Another portion of the oil O that flows into the shaft 31 is discharged from the end of the shaft 31 into the gear housing 61 and is again stored within the gear housing 61. The oil O supplied to the rotating electrical machine 10 absorbs heat from the rotating electrical machine 10. After cooling the rotating electrical machine 10, the oil O falls downward and returns to the gear housing 61.

The present invention is not limited to the above-described embodiment, and modifications to the configuration are possible without departing from the spirit of the present invention, as explained below. In the illustrations of each modified example, the same components as those in the above-described embodiment are given the same reference numerals, and the main differences will be explained below.

<Rotating electric machines>
The rotating electric machine 10 is a part that drives the drive device 100. In this embodiment, the rotating electric machine 10 functions as both an electric motor and a generator.

The rotating electric machine 10 includes a rotor 30 that can rotate around a central axis J, a stator 40 that is positioned radially outward of the rotor 30, and a refrigerant supply unit 50.

(Stator)
The stator 40 faces the rotor 30 in the radial direction with a gap therebetween. The stator 40 is fixed inside the motor housing 65. The stator 40 has a stator core 41 and a coil 42. The stator core 41 is annular and surrounds the central axis J of the rotating electric machine 10. The coil 42 is attached to the stator core 41 via an insulator (not shown).

(Rotor)
As shown in FIG. 2 , the rotor 30 includes an annular rotor core 32 centered on the central axis J, a plurality of magnets 36, a plurality of foam sheets 37, and a shaft 31 (omitted in FIG. 2 ). The rotor 30 also includes a plurality of magnetic poles 3 arranged along the circumferential direction. The rotor 30 of this embodiment includes eight magnetic poles 3. Each magnetic pole 3 includes three magnets 36. The three magnets 36 of one magnetic pole 3 are arranged in mirror symmetry with respect to the magnetic pole center line L. Here, the magnetic pole center line L is a virtual line that passes through the circumferential center of the magnetic pole 3 and the central axis J and extends radially. In this embodiment, the magnetic pole center line L is approximately parallel to the d-axis, which is the direction of the main magnetic flux.

(rotor core)
The rotor core 32 extends in the axial direction around the central axis J. The rotor core 32 has a central hole 32a that penetrates the rotor core 32 in the axial direction. The central hole 32a is substantially circular and has its center on the central axis J. The shaft 31 (see FIG. 1 ) is passed through the central hole 32a in the axial direction.

The rotor core 32 is made of a magnetic material. Although not specifically shown, the rotor core 32 has multiple laminations stacked in the axial direction. The laminations are plate-shaped members. The plate surfaces of the laminations face the axial direction. The laminations are approximately annular plate-shaped, centered on the central axis J. The laminations are, for example, electromagnetic steel plates.

The rotor core 32 is provided with a plurality of magnet holes 38. Each magnet hole 38 is located in a portion of the rotor core 32 other than the central hole 32a. More specifically, when viewed in the axial direction, each magnet hole 38 is located radially outward of the central hole 32a and spaced apart circumferentially. Each magnet hole 38 passes through the rotor core 32 in the axial direction. A magnet 36 and a foam sheet 37 are located in each magnet hole 38.

As shown in Figure 3, the inner wall of each magnet hole 38 has a first wall surface 38a, a second wall surface 38b, and a pair of protrusions 38d.

The first wall surface 38a faces radially outward. A recess 38c is provided on the first wall surface 38a. The recess 38c is located in the center of the first wall surface 38a when viewed in the axial direction. The recess 38c is a groove extending in the axial direction. In this embodiment, the cross section of the recess 38c perpendicular to the axial direction has a shape that is, for example, semicircular or semielliptical. Note that the recess 38c does not necessarily have to be provided on the inner wall of the magnet hole 38.

The second wall surface 38b faces the first wall surface 38a. That is, the second wall surface 38b faces radially inward. The magnet 36 is disposed between the first wall surface 38a and the second wall surface 38b.

A pair of protrusions 38d are provided on the inner wall of the magnet hole 38. The pair of protrusions 38d are arranged at both ends of the first wall surface 38a when viewed in the axial direction. The protrusions 38d protrude from the first wall surface 38a toward the second wall surface 38b. The protrusions 38d extend along the axial direction. In this embodiment, the protrusions 38d are provided over the entire axial length of the magnet hole 38. The magnet 36 is arranged between the pair of protrusions 38d.

A flux barrier portion 38e is provided in the magnet hole 38. The flux barrier portion 38e is located on both sides of the magnet 36 when viewed axially. In this specification, a "flux barrier portion" is a portion that can suppress the flow of magnetic flux. In other words, magnetic flux does not easily pass through the flux barrier portion. The flux barrier portion is not particularly limited as long as it can suppress the flow of magnetic flux, and may include a void portion or a non-magnetic portion such as a resin portion. In this embodiment, the flux barrier portion 38e is a void portion formed by a hole that penetrates the rotor core 32 in the axial direction.

The multiple magnet holes 38 include first magnet holes 38A and second magnet holes 38B. In this embodiment, the number of second magnet holes 38B is twice the number of first magnet holes 38A. The three magnets 36 placed in these three magnet holes 38 constitute one magnetic pole 3. The three magnet holes 38 in which the three magnets 36 that constitute one magnetic pole 3 are placed are referred to as a set S of magnet holes 38.

The pair of second magnet holes 38B in one set S are arranged symmetrically with respect to the magnetic pole center line L, which passes through the center of the magnetic pole 3, as viewed from the axial direction. The second magnet holes 38B on one circumferential side (+θ side) of the magnetic pole center line L extend radially outward as viewed from the axial direction. The second magnet holes 38B on the other circumferential side (-θ side) of the magnetic pole center line L also extend radially outward as viewed from the axial direction. In other words, the circumferential distance between the pair of second magnet holes 38B in one set S gradually increases as they extend radially outward. The first magnet hole 38A is arranged circumferentially between the radially outer ends of the pair of second magnet holes 38B.

(magnet)
One magnet 36 is disposed in each magnet hole 38. The type of magnet 36 is not particularly limited. The magnet 36 may be, for example, a neodymium magnet or a ferrite magnet. In this embodiment, the magnet 36 has a rectangular parallelepiped shape that is elongated in the axial direction. Therefore, the magnet 36 has a rectangular shape when viewed in the axial direction. The magnet 36 extends, for example, from one axial end to the other axial end of the rotor core 32. Note that the axial dimension of the magnet 36 may be shorter than the axial dimension of the rotor core 32 (the axial dimension of the magnet hole 38). Furthermore, the shape of the magnet 36 is not limited to that described above.

Three magnets 36 are arranged in one magnetic pole 3. In the following description, the magnet 36 arranged in the first magnet hole 38A will be referred to as the first magnet 36A. Similarly, the magnet 36 arranged in the second magnet hole 38B will be referred to as the second magnet 36B. In other words, the rotor 30 has a first magnet 36A arranged in the first magnet hole 38A and a second magnet 36B arranged in the second magnet hole 38B. Each magnetic pole 3 includes one first magnet 36A and two second magnets 36B. In this embodiment, the number of second magnets 36B is twice the number of first magnets 36A.

In each magnetic pole 3, the first magnet 36A is arranged perpendicular to the magnetic pole center line L. In addition, in each magnetic pole 3, the two second magnets 36B are arranged radially inward of the first magnet 36A and circumferentially symmetrical with respect to the magnetic pole center line L. Furthermore, in each magnetic pole 3, the two second magnets 36B are spaced apart radially outward.

The first magnet 36A and second magnet 36B are magnetized in the thickness direction. The first magnet 36A and the pair of second magnet holes 38B that make up one magnetic pole 3 each have the same pole facing radially outward. For example, if the surface of the first magnet 36A facing radially outward is a north pole (or south pole), the surfaces of the pair of second magnet holes 38B facing radially outward are also north poles (or south poles).

(Foam sheet)
The foam sheet 37 is disposed between the inner wall of the magnet hole 38 and the magnet 36. As shown in Fig. 4, the foam sheet 37 is a sheet-like member. The foam sheet 37 is attached to the outer surface of the magnet 36 and is inserted into the magnet hole 38 together with the magnet 36.

In this embodiment, the foam sheet 37 is a rectangular, or square, sheet extending in the axial direction. However, the foam sheet 37 is not limited to this, and may be a sheet of any other polygonal, elliptical, or circular shape. The foam sheet 37 placed within the magnet hole 38 foams when heated, expanding in volume and hardening in the expanded state. The expanded foam sheet 37 presses the magnet 36 against the inner wall of the magnet hole 38. This allows the foam sheet 37 to hold the magnet 36 within the magnet hole 38.

As shown in FIG. 5, the foam sheet 37 is constructed by laminating multiple layers. In this embodiment, the foam sheet 37 has a sheet-like substrate portion 37a, a pair of sheet-like foam portions 37c, and a pair of adhesive layers 37d.

The substrate 37a is in the form of a film and is made of, for example, resin. The substrate 37a is made of, for example, polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyimide (PI), or the like.

The pair of foaming portions 37c contain, for example, a thermosetting resin and a foaming agent that can be foamed by heating. The foaming agent preferably foams at a temperature lower than the curing temperature of the thermosetting resin and reaches its most expanded state (maximum foaming state). As a result, during the temperature rise process when the rotor is heated, the thermosetting resin begins to harden after the foaming agent has completed foaming, allowing the foaming sheet 37 to expand stably, and the foaming sheet 37 can stably fix the magnet 36 to the inner wall of the magnet hole 38.

The foaming agent for foam portion 37c can be a low-melting organic solvent, such as microcapsules containing alcohol. The thermosetting resin for foam portion 37c is preferably a thermosetting adhesive. Examples of thermosetting adhesives include phenolic adhesives, urethane adhesives, and epoxy adhesives. Epoxy adhesives are more preferable as they offer superior adhesive strength and chemical resistance.

One of the pair of foam sections 37c is disposed on one side of the base section 37a, and the other is disposed on the other side of the base section 37a. An adhesive layer 37d is provided on the surface of each foam section 37c facing away from the base section 37a. In this embodiment, the pair of foam sections 37c are made of the same material, but they may also be made of different materials.

A pair of adhesive layers 37d are provided on each of the foamed portions 37c. Therefore, the foamed sheet 37 of this embodiment has adhesive layers 37d on both the front and back surfaces. The adhesive layers 37d are adhesive films, and any conventionally known adhesive layer can be used. The adhesive layer 37d is covered, for example, by a release liner (not shown).

In this embodiment, the foam sheet 37 has a pair of adhesive layers 37d on both the front and back surfaces. Therefore, the foam sheet 37 is adhesively fixed to the magnet 36 and also to the inner wall of the magnet hole 38. However, the foam sheet 37 may have an adhesive layer on only one of the front and back surfaces. In other words, it is sufficient that the foam sheet 37 is adhesively fixed to at least one of the magnet 36 and the inner wall of the magnet hole 38 via an adhesive layer.

As shown in FIG. 3, at least one foam sheet 37 is provided between the inner wall of the magnet hole 38 and the magnet 36. In this embodiment, the foam sheet 37 is interposed between the outer surface of the magnet 36 and the first wall surface 38a of the magnet hole 38.

In this embodiment, the recess 38c of the first wall surface 38a is positioned opposite the foam sheet 37. According to this embodiment, for example, the opening edge of the recess 38c catches on the surface of the foam sheet 37, thereby preventing the foam sheet 37 from shifting out of position.

In addition, in this embodiment, when the rotor 30 is manufactured, the foam sheet 37 expands due to heating, pressing the magnet 36 against the second wall surface 38b of the magnet hole 38. As the foam sheet 37 hardens in this state, the magnet 36 and the second wall surface 38b of the magnet hole 38 remain in close contact with each other. Therefore, even if centrifugal force acts on the magnet 36 when the rotor 30 rotates, the magnet 36 is prevented from shifting radially outward within the magnet hole 38.

In this embodiment, the foam sheet 37 is positioned between a pair of protrusions 38d. Therefore, the pair of protrusions 38d can be used to prevent the foam sheet 37 from shifting position within the magnet hole 38.

The multiple foam sheets 37 include a first foam sheet 37A housed in the first magnet hole 38A and a second foam sheet 37B housed in the second magnet hole 38B. That is, the rotor 30 has a first foam sheet 37A and a second foam sheet 37B. The first foam sheet 37A is positioned between the inner wall of the first magnet hole 38A and the first magnet 36A. The second foam sheet 37B is positioned between the inner wall of the second magnet hole 38B and the second magnet 36B. In this embodiment, the number of second foam sheets 37B is twice the number of first foam sheets 37A.

In this embodiment, the first foam sheet 37A and the second foam sheet 37B differ in at least one of the type and thickness of the foam portion 37c shown in Figure 5 and the type of adhesive layer 37d. As a result, the magnetic holding force of the first foam sheet 37A and the magnetic holding force of the second foam sheet 37B differ from each other.

In this specification, the magnet holding force refers to the force with which the foam sheet 37 holds the magnet 36 inside the magnet hole 38. The magnet holding force can be measured, for example, by applying an axial force to the magnet 36 inside the magnet hole 38 and measuring the force at which the magnet 36 begins to move within the magnet hole 38. Whether the magnet holding forces of two foam sheets 37 differ from each other is determined by whether the magnet holding force of one foam sheet 37 is higher than the smaller magnet holding force of the other foam sheet 37, for example, by 10% or more. Note that the ratio used as the criterion for determining whether the two magnet holding forces differ is not limited to 10% and may be, for example, a few percent.

Here, we will explain in more detail how to measure the magnet holding force of the first foam sheet 37A and the second foam sheet 37B. First, the foam sheet 37 to be measured is attached between the outer periphery of the magnet 36 and the inner wall of the magnet hole 38 using the adhesive layer 37d, and then the foam portion 37c is foamed to hold the magnet 36 in place. Next, an axial force is applied to the magnet 36 from the opening on one axial side of the magnet hole 38. The axial force applied to the magnet 36 is gradually increased, and the force when the magnet 36 is displaced axially is recorded as the magnet holding force.

When the type of foamed portion 37c in the foamed sheet 37 is changed, the expansion rate during foaming also changes. Therefore, changing the type of foamed portion 37c also changes the stress that presses the magnet 36 against the magnet hole 38 by the foamed sheet 37, and changes the magnet holding force of the foamed sheet 37.

When the thickness of the foamed portion 37c in the foamed sheet 37 changes, the thickness of the foamed portion 37c after foaming also changes. Therefore, by changing the thickness of the foamed portion 37c, the stress that presses the magnet 36 against the magnet hole 38 by the foamed sheet 37 also changes, and the magnet holding force of the foamed sheet 37 changes.

When the type of adhesive layer 37d in the foam sheet 37 is changed, the adhesive strength between the foam sheet 37 and the magnet 36, or between the foam sheet 37 and the inner wall of the magnet hole 38, changes. Therefore, changing the type of adhesive layer 37d changes the magnet holding strength of the foam sheet 37.

Furthermore, the first foam sheet 37A and the second foam sheet 37B may have different areas to achieve different magnet holding forces. Figures 6 and 7 show schematic diagrams of the first foam sheet 337A and the second foam sheet 337B of a modified example that can be used in this modification. The first foam sheet 337A and the second foam sheet 337B are rectangular and differ in at least one of their axial lengths L1a, L1b or their lengths L2a, L2b in the direction perpendicular to the axial direction. Changing the area of the foam sheet 337 changes the adhesive area between the foam sheet 337 and the magnet 36, or between the foam sheet 337 and the inner wall of the magnet hole 38, and therefore the adhesive force. Therefore, changing the area of the foam sheet 337 changes the magnet holding force.

3, centrifugal forces are applied to the first magnet 36A and the second magnet 36B when the rotor 30 rotates. The center of gravity of the first magnet 36A is located radially outward of the center of gravity of the second magnet 36B . Therefore, the centrifugal force applied to the first magnet 36A is greater than the centrifugal force applied to the second magnet 36B. The force that moves the first magnet 36A away from the first wall surface 38a of the first magnet hole 38A is greater than the force that moves the second magnet 36B away from the first wall surface 38a of the second magnet hole 38B.

According to this embodiment, the first foam sheet 37A has a greater magnet holding force than the second foam sheet 37B. By making the magnet holding force of the first foam sheet 37A greater than that of the second foam sheet 37B, the first magnet 36A can be held in the first magnet hole 38A against centrifugal force. Meanwhile, the second magnet 36B can be held with less force than the first magnet 36A. Therefore, the second foam sheet 37B, which has a lower magnet holding force than the first foam sheet 37A, can be used to hold the second magnet 36B. This means that a cheaper second foam sheet than the first foam sheet 37A can be used for the second foam sheet 37B, allowing the entire rotor 30 to be manufactured at low cost. Furthermore, foam sheets with different magnet holding forces can be used and arranged depending on the centrifugal force applied to the first magnet 36A and the second magnet 36B, thereby more appropriately holding each magnet relative to the rotor core.

In this embodiment, the magnet holding force of the first foam sheet 37A and the magnet holding force of the second foam sheet 37B are different. According to this embodiment, the magnets 36 that are subjected to a large force during operation of the rotor 30 are fixed to the rotor core 32 using foam sheets 37 with a large magnet holding force, and the magnets 36 that are subjected to only a small force are fixed to the rotor core 32 using foam sheets 37 with a small magnet holding force. This allows the use of optimal and inexpensive foam sheets 37 in various locations, thereby reducing the manufacturing cost of the rotor 30.

<Modification>
Next, modifications that can be adopted in the above-described embodiment will be described. In the following description of each modification, the same components as those in the already described embodiment or modification will be assigned the same reference numerals, and the description thereof will be omitted.

(Variation 1)
The rotor 130 of variant 1 shown in Figure 8 differs from the above-mentioned embodiment mainly in that the multiple (four) magnets 136 that make up one magnetic pole 103 are arranged in two sets of V-shapes when viewed from the axial direction.
Similar to the above-described embodiment, the rotor 130 of this modified example includes a rotor core 132, a plurality of magnets 136, and a plurality of foam sheets 137. In this modified example, four of the plurality of magnets 136 form one magnetic pole 103. The rotor 130 includes a plurality of magnetic poles 103.

The multiple magnets 136 include a first magnet 136A and a second magnet 136B. In this modification, one magnetic pole 103 includes two first magnets 136A and two second magnets 136B.

The rotor core 132 is provided with multiple magnet holes 138. Each magnet hole 138 passes through the rotor core 132 in the axial direction. A magnet 136 and a foam sheet 137 are disposed in each magnet hole 138.

The inner wall of the magnet hole 138 has a first wall surface 138a facing radially outward and a second wall surface 138b facing radially inward. The magnet 136 is positioned between the first wall surface 138a and the second wall surface 138b.

The multiple magnet holes 138 include a first magnet hole 138A and a second magnet hole 138B. The second magnet hole 138B is positioned radially outward from the first magnet hole 138A. A first magnet 136A is positioned in the first magnet hole 138A. A second magnet 136B is positioned in the second magnet hole 138B.

In one magnetic pole 103, the two first magnets 136A are arranged circumferentially symmetrically with respect to the magnetic pole center line L, which extends radially. The two first magnets 136A become increasingly spaced apart as they move radially outward. In one magnetic pole 103, the two second magnets 136B are arranged circumferentially symmetrically with respect to the magnetic pole center line L, radially inward of the first magnet 136A. In one magnetic pole 103, the two second magnets 136B become increasingly spaced apart as they move radially outward.

The multiple foam sheets 137 include a first foam sheet 137A housed in the first magnet hole 138A and a second foam sheet 137B housed in the second magnet hole 138B. The first foam sheet 137A is positioned between the inner wall of the first magnet hole 138A and the first magnet 136A. The second foam sheet 137B is positioned between the inner wall of the second magnet hole 138B and the second magnet 136B.

The foam sheet 137 of this modified example is interposed between the outer surface of the magnet 136 and the first wall surface 138a of the magnet hole 138. The foam portion 37c (see Figure 5) of the foam sheet 137 of this modified example expands to press and secure the magnet 136 against the inner wall of the magnet hole 138.

In this modified example, the first foam sheet 137A and the second foam sheet 137B differ in at least one of the type and thickness of the foam portion 37c shown in FIG. 5 and the type of adhesive layer 37d. As a result, the magnetic holding force of the first foam sheet 137A and the magnetic holding force of the second foam sheet 137B differ from each other. Furthermore, the magnetic holding force of the first foam sheet 137A and the magnetic holding force of the second foam sheet 137B may differ due to their different areas.

In this modification, the center of gravity of the first magnet 136A is located radially outward of the center of gravity of the second magnet 136B, so the centrifugal force applied to the first magnet 136A is greater than the centrifugal force applied to the second magnet 136B.

According to this modification, the first foam sheet 137A preferably has a greater magnet holding force than the second foam sheet 137B. By making the magnet holding force of the first foam sheet 137A greater than that of the second foam sheet 137B, the first magnet 136A can be held in the first magnet hole 138A against centrifugal force. Meanwhile, the second magnet 136B can be held with less force than the first magnet 136A. Therefore, the second foam sheet 137B, which has a lower magnet holding force than the first foam sheet 137A, can be used to hold the second magnet 136B. This means that the second foam sheet 137B can be made less expensive than the first foam sheet 137A, allowing the entire rotor 130 to be manufactured at low cost. Furthermore, foam sheets with different magnet holding forces can be used and arranged depending on the differences in centrifugal forces applied to the first magnet and the second magnet, respectively, allowing for more appropriate magnet retention.

(Variation 2)
The rotor 230 of variant 2 shown in Figure 9 differs from the above-mentioned embodiment mainly in that multiple (two) magnets 236 forming one magnetic pole 203 are arranged in a V-shape when viewed from the axial direction.
Similar to the above-described embodiment, the rotor 230 of this modified example includes a rotor core 232, a plurality of magnets 236, and a plurality of foam sheets 237. In this modified example, two of the plurality of magnets 236 form one magnetic pole 203. The rotor 230 includes a plurality of magnetic poles 203.

The multiple magnets 236 include a first magnet 236A and a second magnet 236B. In this modification, one magnetic pole 203 includes one first magnet 236A and one second magnet 236B.

The rotor core 232 is provided with multiple magnet holes 238. Each magnet hole 238 passes through the rotor core 232 in the axial direction. A magnet 236 and a foam sheet 237 are disposed in each magnet hole 238.

The inner wall of the magnet hole 238 has a first wall surface 238a facing radially outward and a second wall surface 238b facing radially inward. The magnet 236 is positioned between the first wall surface 238a and the second wall surface 238b.

The multiple magnet holes 238 include a first magnet hole 238A and a second magnet hole 238B. The first magnet holes 238A and the second magnet holes 238B are arranged alternately in the circumferential direction. A first magnet 236A is disposed in the first magnet hole 238A. A second magnet 236B is disposed in the second magnet hole 238B.

In one magnetic pole 203, the first magnet 236A and the second magnet 236B are arranged circumferentially symmetrically with respect to the magnetic pole center line L, which extends radially. The first magnet 236A and the second magnet 236B become increasingly spaced apart as they move radially outward.

The multiple foam sheets 237 include a first foam sheet 237A housed in the first magnet hole 238A and a second foam sheet 237B housed in the second magnet hole 238B. The first foam sheet 237A is positioned between the inner wall of the first magnet hole 238A and the first magnet 236A. The second foam sheet 237B is positioned between the inner wall of the second magnet hole 238B and the second magnet 236B.

The foam sheet 237 of this modified example is interposed between the outer surface of the magnet 236 and the first wall surface 238a of the magnet hole 238. The foam portion 37c (see Figure 5) of the foam sheet 237 of this modified example expands to press and secure the magnet 236 against the inner wall of the magnet hole 238.

In this modified example, the first foam sheet 237A and the second foam sheet 237B differ in at least one of the type and thickness of the foam portion 37c shown in FIG. 5 and the type of adhesive layer 37d. As a result, the magnetic holding force of the first foam sheet 237A and the magnetic holding force of the second foam sheet 237B differ from each other. Furthermore, the magnetic holding force of the first foam sheet 237A and the magnetic holding force of the second foam sheet 237B may differ due to their different areas.

In the rotor 230, the inertial forces acting on the first magnet 236A and the second magnet 236B are different. For example, when the rotor 230 rotates to one circumferential side (+θ side), the first magnet 236A, which is located on one circumferential side (+θ side) of the magnetic pole center line L, is subjected to an inertial force toward the other circumferential side (-θ side) when the rotor 230 accelerates. As a result, a large force is applied to the first magnet 236A in a direction away from the first wall surface 238a. On the other hand, when the rotor 230 rotates to one circumferential side (+θ side), the second magnet 236B, which is located on the other circumferential side (-θ side) of the magnetic pole center line L, is subjected to an inertial force toward the one circumferential side (+θ side) when the rotor 230 accelerates. As a result, a large force is applied to the first magnet 236A in a direction pressing it against the first wall surface 238a.

In this modified example, the foam sheet 237 is positioned between the first wall surface 238a and the magnet 236. Therefore, the first foam sheet 237A is required to have a magnetic holding force that can hold the first magnet 236A against the force that separates it from the first wall surface 238a. On the other hand, because the second magnet 236B is subjected to a force that presses it against the first wall surface 238a, the magnetic holding force of the second foam sheet 237B need only be smaller than the magnetic holding force of the first foam sheet 237A.

According to this modification, the first foam sheet 237A preferably has a greater magnet holding force than the second foam sheet 237B. By making the magnet holding force of the first foam sheet 237A greater than that of the second foam sheet 237B, the first magnet 236A can be held in the first magnet hole 238A against inertial forces. Meanwhile, the second magnet 236B can be held with less force than the first magnet 236A. Therefore, the second foam sheet 237B, which has a lower magnet holding force than the first foam sheet 237A, can be used to hold the second magnet 236B. This means that the second foam sheet 237B can be made less expensive than the first foam sheet 237A, allowing the entire rotor 230 to be manufactured at low cost. Furthermore, foam sheets with different magnet holding forces can be used and arranged depending on the differences in inertial forces acting on the first magnet 236A and the second magnet 236B, thereby more appropriately holding each magnet.

The rotor 230 of this modified example is particularly effective when rotating only on one circumferential side (+θ side).

In this modification, the two magnets 236 in the magnetic pole 203 are held symmetrically about the magnetic pole center line L using foam sheets 237 with different magnet holding strengths. This configuration can also be used in rotors with other configurations, as long as the rotor has two magnets that are symmetrically arranged circumferentially about the magnetic pole center line L and that move away from each other radially outward. For example, even in a rotor with magnets arranged in a V-shape as viewed axially, such as the magnetic pole 3 or magnetic pole 103, the two magnets that are symmetrically arranged about the magnetic pole center line can be held by the first foam sheet 237A and the second foam sheet 237B of this modification to achieve the above-described effect.
That is, the magnetic holding force of the second foam sheet 37B disposed in the second magnet hole 38B located on one circumferential side ( +θ side) may be different from the magnetic holding force of the second foam sheet 37B disposed in the second magnet hole 38B located on the other circumferential side (−θ side). In this case, the magnetic holding forces of the first foam sheet 37A, the second foam sheet 37B located on one circumferential side (+θ side), and the second foam sheet 37B located on the other circumferential side (−θ side) may be different from one another. The magnetic holding force of the first foam sheet 37A may be the same as that of either the second foam sheet 37B located on one circumferential side (+θ side) or the other circumferential side (−θ side).
The magnetic holding force of the first foamed sheet 137A disposed in the first magnet hole 138A located on one circumferential side (+θ side) may be different from the magnetic holding force of the first foamed sheet 137A disposed in the first magnet hole 138A located on the other circumferential side (−θ side). The magnetic holding force of the first foamed sheet 137B disposed in the second magnet hole 138B located on one circumferential side (+θ side) may be different from the magnetic holding force of the first foamed sheet 137B disposed in the second magnet hole 138B located on the other circumferential side (−θ side). In this case, the magnetic holding force of the first foamed sheet 137A disposed on one circumferential side (+θ side) or the other circumferential side (−θ side) may be the same as the magnetic holding force of at least one of the second foamed sheets 137B disposed on one circumferential side (+θ side) or the other circumferential side (−θ side). In addition, the magnetic holding force of the second foamed sheet 137B located on one circumferential side (+θ side) or the other circumferential side (−θ side) may be the same as the magnetic holding force of at least one of the first foamed sheets 137A located on one circumferential side (+θ side) and the other circumferential side (−θ side).

The rotating electric machine to which the present invention is applicable is not limited to a motor, but may also be a generator. The use of the rotating electric machine is not particularly limited. For example, the rotating electric machine may be mounted on a vehicle for an application other than rotating the axle 64, or may be mounted on equipment other than a vehicle. Furthermore, the attitude in which the rotating electric machine is used is not particularly limited.

The above describes embodiments of the present invention and their variations. However, the individual configurations and combinations thereof in the embodiments and variations are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

3,103,203...magnetic pole, 10...rotating electric machine, 30,130,230...rotor, 32,132,232...rotor core, 36,136,236...magnet, 36A,136A,236A...first magnet, 36B,136B,236B...second magnet, 37,137,237,337...foam sheet, 37A,137A,237A,337A... First foam sheet, 37B, 137B, 237B, 337B... Second foam sheet, 37c... Foam portion, 37d... Adhesive layer, 38, 138, 238... Magnet hole, 38A, 138A, 238A... First magnet hole, 38B, 138B, 238B... Second magnet hole, 40... Stator, 60... Transmission device, 100... Drive device, J... Center axis, L... Magnetic pole center line

Claims (10)

a rotor core having a first magnet hole and a second magnet hole extending axially about a central axis;
a first magnet disposed in the first magnet hole;
a second magnet disposed in the second magnet hole;
a first foam sheet disposed between the inner wall of the first magnet hole and the first magnet;
a second foam sheet disposed between the inner wall of the second magnet hole and the second magnet,
the magnetic holding force of the first foam sheet and the magnetic holding force of the second foam sheet are different from each other;
It has multiple magnetic poles,
Each of the plurality of magnetic poles includes the first magnet and the second magnet.
Rotor. the plurality of magnetic poles including one of the first magnets and two of the second magnets;
In one of the magnetic poles,
The first magnet is disposed perpendicular to a magnetic pole center line extending in a radial direction,
The two second magnets are disposed radially inside the first magnet and symmetrically in the circumferential direction with respect to the magnetic pole center line, and are spaced apart radially outward.
The rotor of claim 1 . the plurality of magnetic poles including two of the first magnets and two of the second magnets;
In one of the magnetic poles,
The two first magnets are arranged symmetrically in the circumferential direction with respect to a magnetic pole center line extending in the radial direction, and are spaced apart from each other as they extend radially outward,
The two second magnets are disposed radially inside the first magnet and symmetrically in the circumferential direction with respect to the magnetic pole center line, and are spaced apart radially outward.
The rotor of claim 1 . the plurality of magnetic poles including the first magnet and the second magnet;
In one of the magnetic poles, the first magnet and the second magnet are arranged symmetrically in the circumferential direction with respect to a magnetic pole center line extending in the radial direction, and are spaced apart from each other as they extend radially outward.
The rotor of claim 1 . The first foam sheet has a stronger magnetic holding force than the second foam sheet.
A rotor according to any one of claims 1 to 4. the first foam sheet and the second foam sheet each have a sheet-like foam portion and an adhesive layer provided on the foam portion;
The first foam sheet and the second foam sheet are different in at least one of the type and thickness of the foam portion and the type of the adhesive layer.
A rotor according to any one of claims 1 to 5. The first foam sheet and the second foam sheet have different areas.
A rotor according to any one of claims 1 to 6. The first foam sheet and the second foam sheet are rectangular, and at least one of the lengths in the axial direction and the lengths in the direction perpendicular to the axial direction is different.
A rotor according to any one of claims 1 to 7. A rotor according to any one of claims 1 to 8;
a stator disposed radially outside the rotor. a rotating electric machine according to claim 9;
a transmission device connected to the rotor,
Drive unit.