JP7797879B2 - Vehicle drive motor device - Google Patents

Description

The technology disclosed herein relates to a motor device for driving a vehicle.

For example, Patent Document 1 discloses an electric motor equipped with a stator having multiple fastening portions (bolt holes) formed on its outer periphery. Specifically, the electric motor disclosed in Patent Document 1 is configured so that at least some of the multiple fastening portions are arranged at uneven intervals in the circumferential direction.

According to Patent Document 1, in the stator core that constitutes the stator, the positions of the antinodes of the vibration modes can be made to not coincide with the positions of the fastening parts, thereby making it possible to suppress, in particular, the circular nth vibration mode.

Japanese Patent Application Laid-Open No. 2017-79519

The inventors of the present application have investigated offsetting the vibration frequency of a stator that constitutes a vehicle drive motor device from the resonant frequency associated with the stator by laying out multiple fastening parts at unequal intervals, as in Patent Document 1. The offset between the vibration frequency and the resonant frequency is useful for suppressing motor noise.

However, when multiple fastening parts are laid out at uneven intervals, excessively widening the spacing between some of the fastening parts could result in a loss of fastening strength for the stator. One way to address this concern is to increase the number of fastening parts. However, increasing the number of fastening parts unnecessarily could bring the vibration frequency and resonance frequency closer together, which could be inconvenient in terms of achieving both suppression of motor noise and vibration.

The technology disclosed here was developed in light of these issues, and its purpose is to ensure fastening strength while suppressing motor noise in vehicle drive motor devices.

A first aspect of the present disclosure relates to a vehicle drive motor device that includes a rotor fixed to a rotating shaft and a stator having a plurality of fastening portions on an outer periphery of one axial end of the rotating shaft, the plurality of fastening portions being spaced apart in the circumferential direction of the outer periphery, and that is supported by an engine with four or more cylinders by fastening via the plurality of fastening portions. In this vehicle drive motor device, the plurality of fastening portions consist of a first fastening portion, a second fastening portion, a third fastening portion, a fourth fastening portion, and a fifth fastening portion that are arranged in order along the circumferential direction, and the stator is supported by one surface of the engine by fastening all five points, the first fastening portion, the second fastening portion, the third fastening portion, the fourth fastening portion, and the fifth fastening portion.

According to the first aspect, the first and second fastening portions are arranged so that the distance between the fastening portions in the circumferential direction is greatest compared to other combinations of fastening portions, and two fastening portions lined up in the circumferential direction among the third fastening portion, the fourth fastening portion, and the fifth fastening portion are arranged adjacent to each other in the circumferential direction so that the distance between the fastening portions in the circumferential direction is smallest compared to other combinations of fastening portions.

Furthermore, according to the first aspect, the distance between the first and second fastening portions is set so that the central angle of the arc connecting the first and second fastening portions is 144° or more and 180° or less.

According to the first aspect, by maximizing the spacing between the first and second fastening portions, the five fastening points are unevenly spaced in the circumferential direction, offsetting the vibration frequency and resonant frequency of the stator. Furthermore, by arranging the third and fourth fastening portions or the fourth and fifth fastening portions adjacent to each other, it is possible to prevent the vibration frequency and resonant frequency from approaching each other, compared to configurations in which a fifth fastening point is set between the first and second fastening portions or where the fifth fastening point is adjacent to the first or second fastening portion. This ensures sufficient fastening strength while suppressing motor noise.

Furthermore, according to intensive studies by the inventors of the present application, by setting the central angle of the arc connecting the first and second fastening portions to 144° or more as in the first aspect, motor noise can be sufficiently suppressed. On the other hand, by setting the central angle of the arc to 180° or less, an excessive offset between the vibration frequency and the resonance frequency can be suppressed, and the influence on other elements constituting the vehicle, such as the engine, can be suppressed.

A second aspect of the present disclosure relates to a vehicle drive motor device that includes a rotor fixed to a rotating shaft and a stator having a plurality of fastening portions on an outer periphery of one axial end of the rotating shaft, the plurality of fastening portions being spaced apart in the circumferential direction of the outer periphery, and that is supported by an engine with four or more cylinders by fastening via the plurality of fastening portions. In this vehicle drive motor device, the plurality of fastening portions consist of a first fastening portion, a second fastening portion, a third fastening portion, a fourth fastening portion, and a fifth fastening portion that are arranged in order along the circumferential direction, and the stator is supported by one surface of the engine by fastening all five points, the first fastening portion, the second fastening portion, the third fastening portion, the fourth fastening portion, and the fifth fastening portion. According to the second aspect, the first and second fastening portions are arranged so that the distance between the fastening portions in the circumferential direction is maximum compared to other combinations of fastening portions, and two fastening portions lined up in the circumferential direction among the third fastening portion, the fourth fastening portion, and the fifth fastening portion are arranged adjacent to each other in the circumferential direction so that the distance between the fastening portions in the circumferential direction is minimum compared to other combinations of fastening portions. Furthermore, according to the second aspect, the distance between two fastening portions arranged adjacent to each other in the circumferential direction is set so that the central angle of the arc connecting the two fastening portions is 36° or less.

According to careful investigations by the inventors of the present application, by setting the central angle of the arc connecting two fastening portions arranged adjacent to each other in the circumferential direction as in the second aspect to 36° or less, motor noise can be suppressed to a level that is audible to the human ear.

Furthermore, according to a third aspect of the present disclosure, the lengths of the distance between the first and second fastening portions, the distance between the second and third fastening portions, the distance between the third and fourth fastening portions, the distance between the fourth and fifth fastening portions, and the distance between the fifth and first fastening portions may all be different, and when the distance between the second and third fastening portions is longer than the distance between the fifth and first fastening portions, the third fastening portion and the fourth fastening portion may be arranged adjacent to each other, and when the distance between the fifth and first fastening portions is longer than the distance between the second and third fastening portions, the fourth fastening portion and the fifth fastening portion may be arranged adjacent to each other.

According to the third aspect, of the two fastening portions located on both circumferential sides of the first and second fastening portions, the two fastening portions are adjacent to each other on one side away from the first and second fastening portions. This allows the two circumferentially adjacent fastening portions to be sufficiently spaced apart from the first and second fastening portions. This is advantageous in terms of both suppressing the approach of the vibration frequency and the resonance frequency and ensuring fastening strength, compared to a configuration in which the first and second fastening portions and the two circumferentially adjacent fastening portions are relatively close to each other.

Furthermore, according to a fourth aspect of the present disclosure, the stator may include a stator core around which a stator coil is wound, and an annular ring having an inner peripheral portion into which the stator core is fitted, the annular ring further having a plurality of flange portions provided on the outer peripheral portion of the annular ring and protruding radially outward from the rotating shaft, the plurality of flange portions being provided corresponding to each of the plurality of fastening portions, and among the plurality of flange portions, the flange portions corresponding to two fastening portions arranged adjacent to each other in the circumferential direction may be integrally formed with each other, and the flange portions corresponding to the other three fastening portions may be formed separately from each other.

According to the fourth aspect, by integrating the flange portions corresponding to two circumferentially adjacent fastening portions, it is possible to suppress the vibration frequency and the resonance frequency from approaching each other, while suppressing an increase in the weight of the components, which is particularly useful in motor devices intended to be mounted on vehicles.

As described above, this disclosure makes it possible to suppress motor noise while ensuring fastening strength in a vehicle drive motor device.

FIG. 1 is a schematic diagram illustrating the configuration of an automobile. FIG. 2 is a side view illustrating the configuration of the powertrain. FIG. 3 is a side view illustrating a schematic configuration of the motor. FIG. 4 is a perspective view illustrating a fastening structure of the stator. FIG. 5 is a rear view illustrating an example of the fastening structure of the stator. FIG. 6 is a perspective view illustrating the configuration of the damper housing. FIG. 7 is an exploded perspective view illustrating the configuration of the stator. FIG. 8 is a front view illustrating the configuration of the annular ring. FIG. 9 is a diagram showing first to fourth comparative examples of the annular ring. FIG. 10 is a plot illustrating the verification results of the upper limit value of the maximum central angle. FIG. 11 is a diagram showing fourth to seventh comparative examples of the annular ring. FIG. 12 is a plot illustrating the verification results of the upper limit of the minimum central angle.

Embodiments of the present disclosure will be described below with reference to the drawings. Please note that the following description is for illustrative purposes only.

(1) Overall Configuration of an Automobile Figure 1 is a schematic diagram illustrating the configuration of an automobile 1 as a vehicle. In the following description, the front, rear, left, right, top, and bottom of the body of the automobile 1 will be simply referred to as front, rear, left, right, top, and bottom, respectively. Here, the left side when looking at the front from the rear of the vehicle is referred to as left, and the right side is referred to as right. The left and right directions are also the vehicle width direction. The up and down direction is also the vehicle height direction, and is also referred to as the height direction. In other figures, the corresponding directions will be referred to as front, rear, left, right, top, and bottom, respectively.

The automobile 1 shown in Figure 1 is a four-wheel hybrid vehicle. As a hybrid vehicle, automobile 1 is equipped with a vehicle drive motor device 3 and an engine 2 that cooperates with this vehicle drive motor device 3 as drive sources. The engine 2 and vehicle drive motor device 3 cooperate to rotate and drive the drive wheels 15R, 15R located at the rear of the vehicle body out of the four wheels 15F, 15F, 15R, 15R. This rotational drive causes automobile 1 to move (run). Hereinafter, vehicle drive motor device 3 will be simply referred to as the "motor."

In the case of this automobile 1, the engine 2 is located at the front of the vehicle body, and the drive wheels 15R are located at the rear of the vehicle body as mentioned above. In other words, automobile 1 is a so-called FR vehicle. Furthermore, in the case of this automobile 1, the engine 2 rather than the motor 3 primarily generates power. The motor 3 is used to assist the driving of the engine 2. In other words, automobile 1 is a so-called mild hybrid vehicle. Furthermore, the motor 3 not only functions as a drive source, but is also used as a generator during regeneration.

Note that the automobile 1 is not limited to a mild hybrid vehicle. The automobile 1 can also be a so-called full hybrid vehicle, in which the motor 3 is primarily used to generate power.

In addition to the engine 2 and motor 3, the automobile 1 is equipped with drivetrain devices such as an inverter 7, a transmission 8, a differential gear 9, and a battery 10. The combination of these devices (drive system) enables the automobile 1 to move.

(2) Powertrain of Automobile Fig. 2 is a side view illustrating the configuration of the powertrain of an automobile 1. As shown in Fig. 2, the powertrain of an automobile 1 is made up of an engine 2, a motor 3, and a transmission 8.

(2-1) Engine The engine 2 is an internal combustion engine that burns, for example, gasoline as fuel. The engine 2 is a so-called four-stroke engine. That is, the engine 2 according to this embodiment generates rotational power by repeating cycles of intake, compression, expansion, and exhaust. Note that the type and form of the engine 2 are not limited to those shown in this embodiment. The engine 2 can take various forms, such as a diesel engine.

The engine 2 is equipped with an output shaft (not shown) that outputs rotational power. This output shaft is positioned approximately in the center of the vehicle width direction, aligned along the fore-and-aft direction of the vehicle body. The automobile 1 is equipped with various systems associated with the engine 2, such as an intake system, an exhaust system, and a fuel supply system. Illustrations and descriptions of these systems are omitted.

In addition, a damper housing 6 is connected to the rear of the engine 2. The engine 2 supports the stator 5 of the motor 3 via this damper housing 6.

(2-2) Transmission The transmission 8 is, for example, an automatic transmission (AT). The transmission 8 has an input shaft at one end and an output shaft at the other end. A transmission mechanism such as a plurality of planetary gear mechanisms, clutches, and brakes is incorporated between the input shaft and the output shaft. By switching between these transmission mechanisms, it is possible to switch between forward and reverse of the automobile 1 and to change the rotation speed between the input shaft and the output shaft of the transmission 8.

The input shaft of the transmission 8 is connected to the rotating shaft of the motor 3. The output shaft of the transmission 8 extends in the longitudinal direction of the vehicle body. This output shaft is connected to the differential gear 9 via a propeller shaft 11 arranged coaxially with the output shaft.

The differential gear 9 is connected to a pair of drive shafts 13, 13. The pair of drive shafts 13, 13 extend in the vehicle width direction and are connected to left and right drive wheels 15R, 15R. The rotational power output via the propeller shaft 11 is distributed to each drive shaft 13 by the differential gear 9, and then transmitted to each drive wheel 15R via each drive shaft 13. A brake 14 is attached to each wheel 15F, 15F, 15R, 15R to brake its rotation.

(2-3) Motor Fig. 3 is a side view illustrating a schematic configuration of the motor 3. Fig. 7 is an exploded perspective view illustrating the configuration of the stator 5, and Fig. 8 is a front view illustrating the configuration of the annular ring 52 of the stator 5.

As shown in Figure 3, the motor 3 includes a shaft 31, a rotor 4, and a stator 5. A rotating magnetic field is generated when three-phase alternating current is supplied to the stator 5, and this rotating magnetic field causes the shaft 31 and rotor 4 to rotate.

The shaft 31 extends in the front-to-rear direction. Hereinafter, the axial direction of the shaft 31 (the direction along the central axis Ac shown in Figure 2, etc.) will be referred to simply as the "axial direction." Similarly, the radial direction of the shaft 31 (the direction extending radially from the central axis Ac) will be referred to simply as the "radial direction," and the radial direction around the shaft 31 (the direction along the circumference centered on the central axis Ac) will be referred to simply as the "circumferential direction."

The rotor 4 has magnets 41 and a magnetic material. The rotor 4 is fixed to the shaft 31, which serves as the rotation axis. The shaft 31 and rotor 4 rotate together. Note that the number and arrangement of the magnets 41 in Figure 3 are merely a general example.

The stator 5 has multiple fastening portions 53 on the outer periphery 52o at one axial end (the axial front end in this embodiment). The multiple fastening portions 53 are spaced apart circumferentially around the outer periphery 52o. The stator 5 is configured to be fastened to the damper housing 6, which serves as the mounting portion, via these multiple fastening portions 53.

Specifically, the stator 5 according to this embodiment includes a stator body 51 and an annular ring 52. The stator body 51 further includes a stator core 51a and multiple stator coils 51b. Each stator coil 51b is wound around the stator core 51a.

The stator core 51a surrounds the rotor 4. The stator core 51a is positioned facing the outer peripheral surface of the rotor 4 at a radial distance. The stator core 51a is also provided with a plurality of teeth 51c arranged in the circumferential direction. Each stator coil 51b is wound in a slot defined between each tooth 51c. Note that the number and arrangement of the stator coils 51b and teeth 51c in Figure 3 are merely a schematic example.

As shown in FIG. 7, the annular ring 52 has an inner circumferential portion 52i into which the stator core 51a and, ultimately, the stator body 51 are fitted. Specifically, the annular ring 52 has an axial dimension that is longer than its radial thickness (the thickness between the inner circumferential portion 52i and the outer circumferential portion 52o), and has an annular shape in which the inner diameter (the length from the central axis Ac to the inner circumferential portion 52i) is longer than its axial dimension. The annular ring 52 can also be considered a motor case that surrounds the outer periphery of the stator core 51a.

Furthermore, the outer periphery 52o at one axial end of the annular ring 52 is provided with multiple flange portions 54 that protrude radially outward. More specifically, the outer periphery 52o at one axial end of the annular ring 52 is provided with a flange-shaped ring that protrudes radially outward around the entire circumference, and each flange portion 54 is formed by partially protruding this flange-shaped ring further.

Each of these flange portions 54 has one or two through holes. The through holes thus provided form the multiple fastening portions 53 described above.

As shown in Figures 7 and 8, the multiple flange portions 54 are arranged at uneven intervals in the radial direction. Therefore, the fastening portions 53 provided on each flange portion 54 are also arranged at uneven intervals in the radial direction.

The number of fastening points for the motor 3 is set to five. In this embodiment, the multiple fastening points 53 consist of a first fastening point 531, a second fastening point 532, a third fastening point 533, a fourth fastening point 534, and a fifth fastening point 535, which are arranged in order along the circumferential direction.

The fastening structure of the stator 5 is described in detail below.

(3) Support Structure of Stator Fig. 4 is a perspective view illustrating an example of the fastening structure of the stator 5, and Fig. 5 is a rear view illustrating an example of the fastening structure of the stator 5. Fig. 6 is a perspective view illustrating an example of the configuration of the damper housing 6.

(3-1) Damper Housing As shown in Fig. 6, the damper housing 6 serving as the mounting portion has a side wall portion 60 extending substantially parallel to the rear surface of the engine 2, and a plurality of boss portions 61 arranged along the periphery of the side wall portion 60. Each of the plurality of boss portions 61 is formed so as to protrude rearward from the wall surface of the side wall portion 60. The damper housing 6 can also be considered as a motor case that surrounds the outer periphery of the stator 5 together with the annular ring 52.

The multiple boss portions 61 consist of a first boss portion 61a provided corresponding to the first fastening portion 531, a second boss portion 61b provided corresponding to the second fastening portion 532, a third boss portion 61c provided corresponding to the third fastening portion 533, a fourth boss portion 61d provided corresponding to the fourth fastening portion 534, and a fifth boss portion 61e provided corresponding to the fifth fastening portion 535.

As shown in Figure 6, the first boss portion 61a to the fifth boss portion 61e are configured to be separate from one another. By placing a fastening portion 53 on each boss portion 61 and tightening a bolt 55 to the fastening portion 53, the annular ring 52 and therefore the stator 5 are connected to the damper housing 6. Each bolt 55 is axially inserted into the fastening portion 53 and boss portion 61 and fastened.

When the motor 3 is driven, a vibratory force (also known as an excitation force) acts on the stator 5. This vibratory force is caused by an electromagnetic force corresponding to the rotation speed, output torque, etc. of the motor 3. When this vibratory force vibrates the stator 5, natural modes such as the toroidal mode are excited in the motor 3, which can result in noticeable sound radiation from the motor 3 (so-called motor noise).

Motor 3 vibrations are transmitted from the annular ring 52 to the damper housing 6 (specifically, from the fastening portion 53 and flange portion 54 to the boss portion 61 and then to the side wall portion 60), and from the damper housing 6 to the engine 2. Similarly, motor 3 vibrations are also transmitted to the transmission 8, etc. Such vibrations, and the noise that accompanies them, are detrimental to ensuring the NVH performance of the automobile 1.

Generally, when sound energy is halved, the sound volume drops by 3 dB. This 3 dB change is considered to be the limit of what human hearing can perceive. By devising innovative designs for the annular ring 52, particularly the multiple fastening portions 53, the inventors have achieved this 3 dB reduction, thereby ensuring the NVH performance of the automobile 1.

(3-2) Multiple Fastening Portions Here, the distance between the first and second fastening portions 531, 532 is defined as a first distance I1, the distance between the second and third fastening portions 532, 533 is defined as a second distance I2, the distance between the third and fourth fastening portions 533, 534 is defined as a third distance I3, the distance between the fourth and fifth fastening portions 534, 535 is defined as a fourth distance I4, and the distance between the fifth and first fastening portions 535, 531 is defined as a fifth distance I5. The lengths of the first distance I1, the second distance I2, the third distance I3, the fourth distance I4, and the fifth distance I5 are all different in this embodiment.

In this case, as shown in Figures 7 and 8, of the multiple fastening portions 53, the first and second fastening portions 531, 532 are arranged so that the circumferential spacing between the fastening portions (first spacing I1) is the largest compared to other combinations of fastening portions. In other words, the first spacing I1 is larger than the second spacing I2, the third spacing I3, the fourth spacing I4, and the fifth spacing I5.

By setting the first interval I1 relatively long, the fastening portion of the stator 5 (fastening portion 53 and flange portion 54) can be made less rigid. Reducing the rigidity of the fastening portion contributes to lowering the frequency of the translational mode of the stator 5 (specifically, the primary resonance of the annular mode). Lowering the frequency of the translational mode makes it possible to offset the vibration frequency and resonance frequency of the stator 5, thereby reducing the transmission of vibration to the damper housing 6.

Furthermore, by arranging the five fastening portions 53 at unequal intervals, the mode shape of the stator 5's annular mode (particularly the mode shape when viewed in a cross section perpendicular to the central axis Ac) can be changed from a point-symmetric shape. This allows the node position of the annular mode to be moved to a location with relatively high rigidity, such as the fourth fastening portion 534 and fifth fastening portion 535 described below. This is effective in suppressing the transmission of vibration to the damper housing 6 through the fastening portions of the stator 5.

The first interval I1 is set so that the central angle θ1 of the arc connecting the first fastening portion 531 and the second fastening portion 532 is preferably between 144° and 180°, and more preferably equal to 144°. Details of this setting will be described later. Hereinafter, the central angle θ1 corresponding to the first interval I1 will also be referred to as the "maximum central angle θ1." In the annular ring 52 according to this embodiment, the maximum central angle θ1 is set to 144°.

However, if the first interval I1 is made excessively long, the fastening strength of the stator 5 may be compromised. To address this concern, a five-point fastening is used in this embodiment, but in order to achieve the benefits of making the first interval I1 relatively long, care must be taken with the placement of each fastening point 53.

Therefore, in this embodiment, of the third fastening portion 533, the fourth fastening portion 534, and the fifth fastening portion 535, any two fastening portions aligned in the circumferential direction are arranged adjacent to each other in the circumferential direction so that the distance between the fastening portions in the circumferential direction is minimized compared to other combinations of fastening portions.

In other words, the third fastening portion 533 and the fourth fastening portion 534, or the fourth fastening portion 534 and the fifth fastening portion 535, are arranged adjacent to each other in the circumferential direction so that the spacing between the fastening portions is minimized compared to other combinations of adjacent fastening portions.

Here, when the second interval I2 is longer than the fifth interval I5, the third fastening portion 533 and the fourth fastening portion 534 are arranged adjacent to each other so that the third interval I3 is minimized. Conversely, when the fifth interval I5 is longer than the second interval I2, the fourth fastening portion 534 and the fifth fastening portion 535 are arranged adjacent to each other so that the fourth interval I4 is minimized.

For example, in this embodiment, as shown in FIG. 8, the fifth interval I5 is longer than the second interval I2, and the fourth fastening portion 534 and the fifth fastening portion 535 are arranged adjacent to each other. In this case, the fourth interval I4 is the smallest compared to the other four intervals.

Furthermore, the interval between two circumferentially adjacent fastening portions (fourth interval I4 in the illustrated example) is set so that the central angle θ2 of the arc connecting the two fastening portions (fourth fastening portion 534 and fifth fastening portion 535 in the illustrated example) is preferably 36° or less. Details of this setting will be described later. Hereinafter, the central angle θ2 that is set to be the smallest is also referred to as the "minimum central angle θ2." In the annular ring 52 according to this embodiment, the minimum central angle θ2 is set to be 10° or greater and 15° or less.

In the illustrated example, the distances decrease in order from the first distance I1 to the fifth distance I5, the third distance I3, the second distance I2, and the fourth distance I4. The fifth distance I5 is set to be the next largest distance after the first distance I1. If the second distance I2 is longer than the fifth distance I5 and the third fastening portion 533 and the fourth fastening portion 534 are positioned adjacent to each other, the second distance I2 may be set to be the next largest distance after the first distance I1.

(3-3) Flange Portion The plurality of fastening portions 53 according to this embodiment are respectively provided on the plurality of flange portions 54 described above. Here, the plurality of flange portions 54 are provided corresponding to each of the plurality of fastening portions 53. Among the plurality of flange portions 54, the flange portions 54 corresponding to two fastening portions arranged adjacent to each other in the circumferential direction are integrally formed with each other, and the flange portions corresponding to the other three fastening portions are formed separately from each other.

For example, in this embodiment, as shown in FIG. 8, the first flange portion 541 corresponding to the first fastening portion 531, the second flange portion 542 corresponding to the second fastening portion 532, and the third flange portion 543 corresponding to the third fastening portion 533 are spaced apart in the circumferential direction and are configured as separate bodies.

On the other hand, the flange portion corresponding to the fourth fastening portion 534 and the flange portion corresponding to the fifth fastening portion 535 are integrated and form a single flange portion (fourth flange portion 544). This fourth flange portion 544 is spaced apart circumferentially from the first flange portion 541, the second flange portion 542, and the third flange portion 543, and is separate from each other.

(4) Comparative Verification of Annular Rings (4-1) Upper and Lower Limits of Maximum Central Angle For example, when five fastening portions 53 are arranged at equal intervals, the magnitude of the maximum central angle θ1 is 72°. On the other hand, the larger the maximum central angle θ1 is, the more significantly the translational mode frequency decreases.

After extensive research, the inventors discovered that if the maximum central angle θ1 is set to more than twice the angle when the angles are evenly spaced, i.e., to more than 72° x 2 = 144°, the motor noise described above is sufficiently reduced, and the sound pressure inside the passenger compartment of automobile 1 is reduced by more than 3 dB.

On the other hand, if the maximum central angle θ1, and therefore the first interval I1, is set too large, the translational mode of the stator 5 will be shifted to an excessively low frequency, which may cause the engine 2 to resonate when the translational mode is transmitted to the engine 2. Therefore, in order to ensure the NV performance of the engine 2, it is necessary to set an upper limit on the maximum central angle θ1.

Figure 9 is a diagram showing a list of first comparative example R1 to fourth comparative example R4 of the annular ring 52.

The first comparative example R1 shows an annular ring in which all five fastening portions 53 are adjacent to each other. The first comparative example R1 is an annular ring in which the maximum central angle θ1 is set as large as possible.

The second comparative example R2 shows an annular ring with a larger maximum central angle θ1 than the annular ring 52 according to this embodiment.

The third comparative example R3 shows an annular ring in which the maximum central angle θ1 is set smaller than that of the annular ring 52 according to this embodiment.

The fourth comparative example R4 shows an annular ring with five fastening portions arranged at equal intervals. The fourth comparative example R4 is an annular ring in which the maximum central angle θ1 is set as small as possible.

Figure 10 is a plot illustrating the results of verifying the upper limit of the maximum central angle θ1. In the figure, the horizontal axis represents the magnitude of the maximum central angle θ1 (labeled "adjacent angle Max" in the figure), and the vertical axis represents the magnitude of the frequency of the translational mode.

In FIG. 10, plot P0 corresponds to the annular ring 52 according to this embodiment. Similarly, plot P1 corresponds to the first comparative example R1, plot P2 corresponds to the second comparative example R2, plot P3 corresponds to the third comparative example R3, and plot P4 corresponds to the fourth comparative example R4.

In addition, line L1 in Figure 10 indicates the frequency (approximately 300 Hz) at which resonance is a concern in a four-cylinder engine, and line L2 in the same figure indicates the frequency (200 Hz) at which resonance is a concern in a six-cylinder engine. In addition, curve L3 in Figure 10 indicates a fitting curve that passes through the vicinity of plots P0 to P4.

As shown by the intersection of curve L3 and line L1, in order to achieve a translational mode frequency of approximately 200 Hz or higher, the maximum central angle θ1 must be set to 180° or less (see θ1_max in Figure 10). Also, as shown by the intersection of curve L3 and line L2, in order to achieve a translational mode frequency of approximately 300 Hz or higher, the maximum central angle θ1 must be set to 144° or less.

In other words, to ensure NV performance in a four-cylinder engine, the maximum central angle θ1 must be set to 180° or less, and to ensure NV performance in both four-cylinder and six-cylinder engines, the maximum central angle θ1 must be set to 144° or less.

In other words, if the maximum central angle θ1 is set to 180° or more, as in plots P1 and P2, the frequency of the translational mode will be below both lines L1 and L2, although the lower limit of the maximum central angle θ1 is exceeded. In this case, although motor noise is suppressed, the NV performance of engine 2 cannot be ensured, regardless of whether it is a four-cylinder engine or a six-cylinder engine.

On the other hand, if the maximum central angle θ1 is set significantly smaller than in this embodiment, as in plots P3 and P4, the frequency of the translational mode will exceed both lines L1 and L2, but the magnitude of the maximum central angle θ1 will fall below the lower limit value mentioned above. In this case, the NV performance of the engine 2 will be ensured, but motor noise will not be sufficiently suppressed.

Based on the above, it is preferable to set the maximum central angle θ1 to between 144° and 180° for a four-cylinder engine, and to 144° for a six-cylinder engine, as the upper and lower limit values that can simultaneously suppress motor noise and improve the NV performance of engine 2.

(4-2) Upper Limit of Minimum Central Angle Furthermore, if the minimum central angle θ2, and therefore the fourth interval I4, is set too large, the translational mode frequency may not be sufficiently reduced, which may hinder the reduction of motor noise. Therefore, in order to sufficiently reduce motor noise, it is necessary to set an upper limit on the minimum central angle θ2.

Figure 11 shows the fourth comparative example R4 to the seventh comparative example R7 of the annular ring 52. Of these, the fourth comparative example R4 is the same as the one shown in Figure 9.

The fifth comparative example R5 is an annular ring in which the minimum central angle θ2 is set slightly wider than the annular ring 52 according to this embodiment. The minimum central angle θ2 in the fifth comparative example R5 is set to the aforementioned upper limit of 36° or less. Furthermore, the maximum central angle θ1 in the fifth comparative example R5 is set to approximately 144°. Therefore, the fifth comparative example R5 can be considered another example of the present disclosure.

The sixth comparative example R6 shows an annular ring with an even wider minimum central angle θ2 than the fifth comparative example R5. The minimum central angle θ2 in the sixth comparative example R6 is set slightly above the upper limit of 36° mentioned above. Furthermore, the maximum central angle θ1 in the sixth comparative example R6 is set to approximately 144°.

The seventh comparative example R7 shows an annular ring with an even wider minimum central angle θ2 than the sixth comparative example R6. The minimum central angle θ2 in the seventh comparative example R7 is even larger than that in the fourth comparative example R4. Furthermore, the maximum central angle θ1 in the seventh comparative example R7 is set to approximately 144°.

Figure 12 is a plot illustrating the results of verifying the upper limit of the minimum central angle θ2. In the figure, the horizontal axis represents the magnitude of the minimum central angle θ2 (labeled "angle between adjacent fastening points" in the figure), which indicates the magnitude of the sound pressure inside the vehicle.

In addition, in Figure 12, plot P0 corresponds to the annular ring 52 according to this embodiment, as in Figure 10. Similarly, plot P5 corresponds to the fifth comparative example R5, plot P6 corresponds to the sixth comparative example R6, plot P7 corresponds to the seventh comparative example R7, and plot P4 corresponds to the fourth comparative example R4, as in Figure 10.

In addition, straight line L4 in Figure 12 extends parallel to the horizontal axis and represents a reference line that reduces the interior sound pressure by approximately 3 dB (see symbol ΔN) compared to plot P4 corresponding to the fourth comparative example R4. Also, curve L5 in Figure 12 represents a fitting curve that passes through the vicinity of plot P0 and plots P4 to P7.

As shown by plots P0, P4 to P7, and curve L5, the interior sound pressure monotonically decreases as the minimum central angle θ2 decreases. Furthermore, as shown by the intersection of curve L5 and line L4, in order to reduce the interior sound pressure by 3 dB or more, the minimum central angle θ2 must be set to 36° or less (see θ2_max in Figure 12).

In other words, in order to provide five fastening points and sufficiently suppress motor noise, the minimum central angle θ2 must be set to 36° or less.

In other words, if the minimum central angle θ2 is set to exceed 36°, as in plots P6 and P7, the fastening strength of the stator 5 is ensured, but motor noise is not sufficiently suppressed even if the maximum central angle θ1 is set to 144°.

On the other hand, as shown in plots P0 and P5, if the minimum central angle θ2 is set to 36° or less, the fastening strength of the stator 5 is ensured while motor noise is sufficiently suppressed.

For these reasons, it is preferable to set the minimum central angle θ2 to 36° or less, as this is the upper limit that allows for both the fastening strength of the stator 5 and the suppression of motor noise.

(5) Achieving Both Motor Noise Suppression and Fastening Strength As described above, according to this embodiment, by maximizing the spacing (first spacing I1) between the first and second fastening portions 531, 532, the five fastening points are unevenly spaced in the circumferential direction, and the resonant frequency can be offset from the vibration frequency of the stator 5. Furthermore, as illustrated in FIG. 8 , by arranging the third and fourth fastening portions 533, 534 or the fourth and fifth fastening portions 534, 535 adjacent to each other, the vibration frequency and the resonant frequency can be prevented from approaching each other, compared to a configuration in which a fifth fastening point is set between the first and second fastening portions 531, 532 or in which the fifth fastening point is adjacent to the first fastening portion 531 or the second fastening portion 532. This makes it possible to ensure fastening strength while suppressing motor noise.

Furthermore, as shown in FIG. 8, of the two fastening portions located on both circumferential sides of the first and second fastening portions 531, 532, the two fastening portions are adjacent to one side away from the first and second fastening portions 531, 532. This allows the two adjacent fastening portions to be sufficiently spaced apart from the first and second fastening portions 531, 532. This is advantageous in terms of both suppressing the approach of the vibration frequency and the resonant frequency and ensuring fastening strength, compared to a configuration in which the first and second fastening portions 531, 532 and the two circumferentially adjacent fastening portions are relatively close to each other.

Furthermore, by integrating the flange portions corresponding to two circumferentially adjacent fastening portions, as in the fourth flange portion 544 shown in Figure 8, it is possible to prevent the vibration frequency and the resonant frequency from approaching each other while also suppressing an increase in component weight. Reducing component weight is particularly useful for motors 3 intended to be installed in automobiles 1.

Furthermore, as explained with reference to FIG. 10, motor noise can be sufficiently suppressed by setting the central angle θ1 of the arc connecting the first and second fastening portions 531, 532 to 144° or more. On the other hand, by setting the central angle of that arc to 180° or less, excessive offset between the vibration frequency and the resonant frequency can be suppressed, and the impact on other elements that make up the vehicle, such as the engine 2, can be suppressed.

Furthermore, as explained with reference to Figure 12, by setting the central angle θ2 of the arc connecting two circumferentially adjacent fastening portions to 36° or less, motor noise can be suppressed to a level that is noticeable to the human ear.

1. Automobiles (vehicles)
2 engine 3 motor (vehicle drive motor device)
31 Shaft (rotating axis)
4 Rotor 5 Stator 51 Stator body 51a Stator core 51b Stator coil 52 Annular ring 52i Inner peripheral portion 52o Outer peripheral portion 53 Multiple fastening portions 531 First fastening portion 532 Second fastening portion 533 Third fastening portion 534 Fourth fastening portion 535 Fifth fastening portion 54 Multiple flange portions 541 First flange portion 542 Second flange portion 543 Third flange portion 544 Fourth flange portion 6 Damper housing (mounted portion)
Ac: central axis I1; first interval I2; second interval I3; third interval I4; fourth interval I5; fifth interval θ1: maximum central angle (central angle of arc)
θ2 Minimum central angle (central angle of the arc)

Claims (4)

A vehicle drive motor device comprising: a rotor fixed to a rotating shaft; and a stator having a plurality of fastening portions on an outer periphery of one axial end of the rotating shaft, the plurality of fastening portions being spaced apart in the circumferential direction of the outer periphery; and the vehicle drive motor device being supported by an engine having four or more cylinders by fastening via the plurality of fastening portions,
the plurality of fastening portions include a first fastening portion, a second fastening portion, a third fastening portion, a fourth fastening portion, and a fifth fastening portion arranged in order along the circumferential direction,
the stator is supported by one surface of the engine by fastening all five points, i.e., the first fastening portion, the second fastening portion, the third fastening portion, the fourth fastening portion, and the fifth fastening portion,
the first and second fastening portions are arranged so that a distance between the fastening portions in the circumferential direction is maximized compared to other combinations of fastening portions;
two fastening portions arranged side by side in the circumferential direction among the third fastening portion, the fourth fastening portion, and the fifth fastening portion are disposed adjacent to each other in the circumferential direction so that a distance between the fastening portions in the circumferential direction is smallest compared to other combinations of fastening portions ;
The distance between the first and second fastening portions is set so that the central angle of the arc connecting the first and second fastening portions is 144° or more and 180° or less.
A vehicle drive motor device comprising: A vehicle drive motor device comprising: a rotor fixed to a rotating shaft; and a stator having a plurality of fastening portions on an outer periphery of one axial end of the rotating shaft, the plurality of fastening portions being spaced apart in the circumferential direction of the outer periphery; and the vehicle drive motor device being supported by an engine having four or more cylinders by fastening via the plurality of fastening portions,
the plurality of fastening portions include a first fastening portion, a second fastening portion, a third fastening portion, a fourth fastening portion, and a fifth fastening portion arranged in order along the circumferential direction,
the stator is supported by one surface of the engine by fastening all five points, i.e., the first fastening portion, the second fastening portion, the third fastening portion, the fourth fastening portion, and the fifth fastening portion,
the first and second fastening portions are arranged so that a distance between the fastening portions in the circumferential direction is maximized compared to other combinations of fastening portions;
two fastening portions arranged side by side in the circumferential direction among the third fastening portion, the fourth fastening portion, and the fifth fastening portion are disposed adjacent to each other in the circumferential direction so that a distance between the fastening portions in the circumferential direction is smallest compared to other combinations of fastening portions;
The interval between the two fastening portions arranged adjacent to each other in the circumferential direction is set so that the central angle of the arc connecting the two fastening portions is 36° or less.
A vehicle drive motor device comprising: 3. The vehicle drive motor device according to claim 1 ,
the lengths of the interval between the first and second fastening portions, the interval between the second and third fastening portions, the interval between the third and fourth fastening portions, the interval between the fourth and fifth fastening portions, and the interval between the fifth and first fastening portions are all different;
When the distance between the second and third fastening portions is longer than the distance between the fifth and first fastening portions, the third fastening portion and the fourth fastening portion are disposed adjacent to each other;
A motor device for driving a vehicle, characterized in that when the distance between the fifth and first fastening portions is longer than the distance between the second and third fastening portions, the fourth fastening portion and the fifth fastening portion are arranged adjacent to each other. 4. The vehicle drive motor device according to claim 1 ,
The stator includes:
a stator core around which a stator coil is wound;
an annular ring having an inner circumferential portion into which the stator core is fitted,
the annular ring further includes a plurality of flange portions provided on an outer periphery of the annular ring and protruding radially outward from the rotary shaft,
the plurality of flange portions are provided corresponding to the plurality of fastening portions,
A motor device for driving a vehicle, characterized in that, among the plurality of flange portions, the flange portions corresponding to two fastening portions arranged adjacent to each other in the circumferential direction are constructed integrally with each other, and the flange portions corresponding to the other three fastening portions are constructed separately from each other.