Drive unit

Abstract

To provide a drive system for vehicles. [Solution] The drive device comprises a first case housing a motor and a gear unit mechanically connected to it. The drive device comprises a second case attached to the first case, forming a housing chamber between the second case and the first case for housing a power conversion circuit board electrically connected to the motor. The first case has a first opposing surface facing the housing chamber. The second case has a second opposing surface facing the first opposing surface across the housing chamber. A projection is provided on one of the first and second opposing surfaces. A fitting portion is provided on the other of the first and second opposing surfaces to receive the projection. The projection and the fitting portion are fitted together in an interference fit manner.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a drive device for a vehicle.

Background Art

[0002] The drive device for a vehicle disclosed in Patent Document 1 has a configuration in which a sound-absorbing cover provided with a sound-absorbing material is attached to a case that houses a gear unit. The sound-absorbing cover can reduce vibrations and noise radiated from the gear unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a known drive device in which a first case that houses a gear unit and a second case that houses a substrate for power conversion are integrated. In such a drive device, vibrations generated from the gear unit may be transmitted to the second case through the first case, and the second case may produce sound. In order to suppress this sound generation phenomenon, when separately attaching a soundproof component such as a sound-absorbing cover, there are problems such as an increase in fastening components such as bolts and a need for a mounting space for the fastening components.

Means for Solving the Problems

[0005] A vehicle drive system disclosed herein comprises a first case housing a motor and a mechanically connected gear unit. The drive system comprises a second case mounted on the first case, forming a housing chamber between the second case and the first case for housing a power conversion circuit board electrically connected to the motor. The first case has a first opposing surface facing the housing chamber. The second case has a second opposing surface facing the first opposing surface across the housing chamber. A projection is provided on one of the first and second opposing surfaces. A fitting portion is provided on the other of the first and second opposing surfaces to receive the projection. The projection and the fitting portion are fitted together in an interference fit manner.

[0006] According to the above configuration, the second opposing surface of the second case can be fixed to the first opposing surface via the protruding portion and the fitting portion. Since the amplitude of vibration of the second opposing surface can be reduced, sound can be suppressed. Furthermore, since the second opposing surface can be fixed in an interference fit manner, the same effect as fastening can be obtained without requiring fastening parts such as bolts. This makes it possible to suppress the cost increase and bulk increase that would be associated with an increase in fastening parts. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-sectional view showing the schematic configuration of the drive unit 1. [Figure 2] This is an exploded perspective view of the casing 10. [Figure 3] This diagram shows the mechanism of the NV phenomenon. [Figure 4] This is a cross-sectional view showing the schematic configuration of the comparative example drive unit 101. [Figure 5] This is a cross-sectional view showing the schematic configuration of the drive unit 201 of Example 2. [Figure 6] This is an exploded perspective view of the casing 310 of Example 3. [Modes for carrying out the invention]

[0008] The fitting portion may be located on the first opposing surface. The protruding portion may be located on the second opposing surface. The protruding portion may be formed integrally with the second opposing surface.

[0009] In some cases, sufficient space may not be available near the second opposing surface due to the presence of circuit boards and other components housed in the containment chamber. With the above configuration, since the protrusion is integrally formed with the second opposing surface, fastening components or the like are not required to fix the protrusion to the second opposing surface. Even when there is insufficient space near the second opposing surface, the protrusion can be positioned on the second opposing surface.

[0010] The substrate may comprise a first substrate and a second substrate arranged along a second opposing surface. The protrusion may be located between the first substrate and the second substrate.

[0011] According to the above configuration, by arranging the protrusions between the substrates, it becomes possible to increase the degree of freedom in the arrangement layout of the protrusions.

[0012] The protruding portion may have a flat plate shape. The fitting portion may have a groove corresponding to the flat plate shape.

[0013] By making the protruding portion a flat plate shape, the rigidity of the protruding portion can be maintained even when the distance between the first substrate and the second substrate is small.

[0014] The protruding portion may have a columnar shape. The fitting portion may have a hole corresponding to the columnar shape. [Examples]

[0015] (Configuration of drive unit 1) FIG. 1 is a cross-sectional view showing a schematic configuration of a drive device 1 according to the present embodiment. The drive device 1 is mounted on an electric vehicle. The drive device 1 is an integrated device that houses a motor 20, a gear unit 30, and a substrate 40 for power conversion in a casing 10. FIG. 2 shows an exploded perspective view of the casing 10. In FIG. 2, the description of the motor 20, the gear unit 30, and the substrate 40 is omitted.

[0016] The casing 10 includes a first case 11 and a second case 12. The first case 11 and the second case 12 may be castings. The motor 20 and the gear unit 30 are housed in the first case 11. Since the specific structure of the motor 20 is well-known, the description thereof is omitted. The gear unit 30 is mechanically connected to the motor 20. The gear unit 30 is a mechanism that decelerates the rotation output from the motor 20 and outputs it to the outside. The gear unit 30 may include, for example, a planetary gear mechanism, a differential gear, various gears, and the like. The first case 11 includes an upper wall 11u. The upper surface of the upper wall 11u is a first opposing surface OS1. The second case 12 is attached to the first opposing surface OS1.

[0017] The second case 12 has a box shape having side walls 12s and an upper wall 12u. An opening AP is provided on the lower side of the second case 12. The opening AP is closed by the first opposing surface OS1. Thereby, an accommodation chamber CR is formed between the second case 12 and the first case 11.

[0018] The lower surface of the upper wall 12u of the second case 12 is a second opposing surface OS2. The second opposing surface OS2 faces the first opposing surface OS1 with the accommodation chamber CR interposed therebetween. The upper surface of the upper wall 12u is an upper surface US. The upper surface US is a surface on the opposite side of the first opposing surface OS1 and is exposed on the surface of the second case 12.

[0019] The accommodation chamber CR houses the substrate 40. The substrate 40 is an electronic device for power conversion and is a part for controlling the power supplied to the motor 20 and the generated power. Examples of the components included in the substrate 40 include an inverter, a converter, etc. The substrate 40 is electrically connected to the motor 20 by wiring not shown. Although other components such as a cooling device are also housed in the accommodation chamber CR, the description is omitted.

[0020] The substrate 40 includes a first substrate 41 and a second substrate 42. The first substrate 41 and the second substrate 42 are arranged along the second opposing surface OS2. That is, the first substrate 41 and the second substrate 42 are arranged side by side in a direction (x direction) parallel to the second opposing surface OS2 in the vicinity of the second opposing surface OS2. The distance between the first substrate 41 and the second substrate 42 is D1.

[0021] A protruding portion 52 is arranged on the second opposing surface OS2. As shown in FIG. 2, the protruding portion 52 has a flat plate shape extending in the y direction. The plate width of the protruding portion 52 in the x direction is W2. The plate width W2 is smaller than the distance D1. Also, the protruding portion 52 is located between the first substrate 41 and the second substrate 42. Thereby, the protruding portion 52 is located substantially at the center of the width of the second opposing surface OS2 in the x direction. The protruding portion 52 is formed integrally with the second opposing surface OS2. The protruding portion 52 may be integrally formed, for example, during the casting of the second case 12. The protruding portion 52 may be a rib.

[0022] A fitting portion 51 is arranged on the first opposing surface OS1. The fitting portion 51 is a member for receiving the protruding portion 52. As shown in FIG. 2, the fitting portion 51 extends in the y direction. The fitting portion ​51 includes a groove 51t corresponding to the flat plate shape of the protruding portion 52. The groove width of the groove 51t in the x direction is W1. The fitting portion 51 may be integral with the first opposing surface OS1. The fitting portion 51 may be integrally formed, for example, during the casting of the first case 11. Also, the fitting portion 51 may be a separate component from the first opposing surface OS1 and may be fixed to the first opposing surface OS1 by fastening components or welding not shown. Also, the material of the fitting portion 51 may be various, such as metal or resin.

[0023] The groove width W1 is slightly smaller than the plate width W2. In other words, there is an interference fit. When fastening the second case 12 to the first case 11 from the state shown in Figure 2, the lower end of the protrusion 52 slides into contact with the inside of the groove 51t and is fitted into place. Specifically, by applying pressure, the protrusion 52 is pressed into the groove 51t. As a result, the protrusion 52 and the fitting part 51 are fitted together in an interference fit manner.

[0024] (Mechanism of noise and vibration generation) Figure 3 illustrates the generation mechanism of noise and vibration (NV) phenomena. The forcing force generated at the forcing source is transmitted to the transmission system via the resonant system (or without passing through the resonant system). The transmission system then transmits the forcing force to the radiating system and the response system. The forcing force transmitted to the radiating system becomes the source of noise. The forcing force transmitted to the response system also becomes the source of noise and vibration.

[0025] The technology described herein focuses on the transmission system in this generation mechanism. Specifically, by reducing the vibration transmission sensitivity of the transmission system, the transmission of forcing forces to the radiation system and response system is suppressed. This makes it possible to suppress noise and vibration. This is explained below.

[0026] (assignment) The problem will be explained using the comparative example drive device 101 shown in Figure 4. The comparative example drive device 101 (Figure 4) differs from the drive device 1 (Figure 1) of this embodiment only in that it does not have a fitting portion 51 and a protruding portion 52. In the drive device 101, the internal components of the first case 11 are the source of the coercive force. An example of a source of coercive force is the gear unit 30 which has a meshing transmission error. The generated coercive force is transmitted by the transmission system described in Figure 3. Specifically, the coercive force generated in the gear unit 30 is transmitted to the upper wall 12u via the side walls 12s of the first case 11 and the second case 12 (see Figure 4, arrow A1).

[0027] Because the first substrate 41 and the second substrate 42 are located near the second opposing surface OS2 of the upper wall 12u, it is difficult to place fastening components for fixing noise suppression components (see region R11). Examples of noise suppression components include reinforcing components, soundproofing covers, and dynamic dampers. Examples of fastening components include bolts. Similarly, due to constraints from other mounted components, it is difficult to place fastening components for fixing noise suppression components on the upper surface US of the upper wall 12u (see region R12). Therefore, the upper wall 12u is a wide flat plate where vibration is not suppressed by noise suppression components. In other words, the upper wall 12u is in a state where the vibration transmission sensitivity of the transmission system, as explained in Figure 3, is high. As a result, forcing forces are easily transmitted to the radiation system and response system, making the upper wall 12u very prone to generating noise.

[0028] (effect) In the technology described herein, the second opposing surface OS2 of the upper wall 12u of the second case 12 can be fixed to the first opposing surface OS1 via the protrusion 52 and the fitting portion 51. Because the rigidity of the second opposing surface OS2 is increased, the amplitude of vibration of the second opposing surface OS2 can be reduced. This reduces the vibration transmission sensitivity of the transmission system, thereby suppressing the sound of the upper wall 12u. Furthermore, since the second opposing surface OS2 can be fixed in an interference fit manner, the same effect as fastening can be obtained without requiring fastening components such as bolts. This makes it possible to suppress cost increases and size increases associated with an increase in fastening components.

[0029] In some cases, the substrate 40 housed in the housing chamber CR may prevent sufficient space from being secured near the second opposing surface OS2 (see Figure 1, region R1). In the technology described herein, since the protrusion 52 is integrally formed with the second opposing surface OS2, fastening components or the like are not required to fix the protrusion 52 to the second opposing surface OS2. Even when there is insufficient space near the second opposing surface OS2, the protrusion 52 can be positioned on the second opposing surface OS2.

[0030] To effectively suppress the sound of the upper wall 12u, it is preferable to position the protrusion 52 approximately in the center of the upper wall 12u. However, for example, when using one large substrate, the degree of freedom in the placement layout of the protrusion 52 is reduced, making it difficult to position the protrusion 52 approximately in the center of the upper wall 12u. Therefore, in the technology described herein, the substrate 40 is divided into a first substrate 41 and a second substrate 42, and the protrusion 52 is placed between the two substrates. This increases the degree of freedom in the placement layout of the protrusion 52, making it possible to position the protrusion 52 approximately in the center of the upper wall 12u. This effectively suppresses the sound of the upper wall 12u.

[0031] When the distance D1 between the first substrate 41 and the second substrate 42 is small, it may be difficult to ensure the rigidity of the protrusion 52 positioned between the first substrate 41 and the second substrate 42. In the technology of this specification, by making the protrusion 52 a flat plate shape, it is possible to maintain the rigidity of the protrusion 52 even when the distance D1 is small. [Examples]

[0032] Figure 5 shows the drive unit 201 of Embodiment 2. Embodiment 2 differs from Embodiment 1 in that the positions of the fitting portion 51 and the protruding portion 52 are reversed. In both embodiments, the same reference numeral is used for common parts, and their descriptions are omitted.

[0033] The protruding portion 52 is located on the first opposing surface OS1. The protruding portion 52 is formed integrally with the first opposing surface OS1. The fitting portion 51 is located on the second opposing surface OS2. The protruding portion 52 and the fitting portion 51 are fitted together in an interference fit manner.

[0034] In this embodiment 2, the first substrate 41 and the second substrate 42 are located near the first opposing surface OS1. Therefore, it is difficult to place fastening components for fixing noise reduction components on the first opposing surface OS1 (see region R21). On the other hand, there is space near the second opposing surface OS2 (see region R22). Therefore, by integrally forming the protrusion 52 on the first opposing surface OS1, it becomes possible to place the protrusion 52 on the first opposing surface OS1 even when there is insufficient space. Furthermore, the fitting portion 51 can be placed on the second opposing surface OS2 where space exists. [Examples]

[0035] Figure 6 shows the casing 310 of Example 3. Example 3 differs from Example 1 in the shape of the fitting portion 51 and the protruding portion 52. Note that common parts in both examples are denoted by the same reference numerals, and their descriptions are omitted.

[0036] The projection 52 has a cylindrical shape extending in the z direction. The lower end of the projection 52 has an outer diameter r2. The fitting portion 51 has a hole 51h corresponding to the cylindrical shape of the projection 52. The hole 51h has an inner diameter r1. The inner diameter r1 is slightly smaller than the outer diameter r2. As a result, the projection 52 and the fitting portion 51 can be fitted together in an interference fit manner.

[0037] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself.

[0038] (modified version) The shapes of the fitting portion 51 and the protruding portion 52 are not limited to flat plates or cylinders, but can be various shapes. For example, they may be prism-shaped. Also, the number of pairs of fitting portions 51 and protruding portions 52 is not limited to one, but may be two or more.

[0039] The manner in which the substrate 40 is divided can vary, and for example, the substrate 40 may be composed of three or more components.

[0040] The drive unit 1 may be any device in which at least one power source and a circuit board are integrated. For example, the drive unit 1 may be a device in which a gear unit and a circuit board are integrated.

[0041] The vehicles on which the drive system described herein is installed are not limited to electric vehicles. The drive system described herein can be installed in, for example, hybrid vehicles and plug-in hybrid vehicles. In this case, the drive system described herein may house multiple motors or a planetary gear mechanism within the casing. Furthermore, the drive system described herein is also applicable to vehicles that use electric motors for at least part of their propulsion, such as fuel cell vehicles. [Explanation of symbols]

[0042] 1: Drive unit 10: Casing 11: First case 12: Second case 40: Circuit board 41: First circuit board 42: Second circuit board 51: Fitting part 52: Protruding part OS1: First opposing surface OS2: Second opposing surface CR: Housing chamber

Claims

1. A drive system for a vehicle, A first case housing a motor and a mechanically connected gear unit, A second case is attached to the first case and has a housing chamber between it and the first case for housing a power conversion circuit board that is electrically connected to the motor, Equipped with, The first case is provided with a first opposing surface facing the containment chamber, The second case is provided with a second opposing surface that faces the first opposing surface across the housing chamber, A protrusion is provided on one of the first opposing surface and the second opposing surface. A fitting portion for receiving the protrusion is provided on the other of the first opposing surface and the second opposing surface. The protruding portion and the fitting portion are fitted together in an interference fit manner. Drive unit.

2. The aforementioned fitting portion is arranged on the first opposing surface, The aforementioned protrusion is positioned on the second opposing surface, The drive device according to claim 1, wherein the protruding portion is formed integrally with the second opposing surface.

3. The substrate comprises a first substrate and a second substrate arranged along the second opposing surface, The drive device according to claim 2, wherein the protruding portion is located between the first substrate and the second substrate.

4. The aforementioned protrusion has a flat plate shape, The drive device according to claim 3, wherein the fitting portion is provided with a groove corresponding to the flat plate shape.

5. The aforementioned protruding portion has a columnar shape, The drive device according to claim 1, wherein the fitting portion is provided with a hole corresponding to the column shape.

Images