Device

Abstract

[Problem] To reduce noise radiated from a drive shaft. [Solution] This device comprises a motor, an inverter that drives the motor, a gear device connected to the downstream side of the motor, and a drive shaft that transmits the power of the motor transmitted from the gear device to a drive wheel. The drive shaft has a part coated with a noise-reducing material.

Description

[Technical Field]

[0001] The present invention relates to an apparatus. [Background technology]

[0002] Patent Document 1 discloses a device including a motor and an inverter that drives the motor. A gear device is connected downstream of the motor. A drive shaft is connected downstream of the gear device. Power (rotational force) generated by the motor is transmitted to the drive wheels via the gear device and the drive shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-147293 Summary of the Invention [Problem to be solved by the invention]

[0004] High-frequency noise is generated when inverter transistors repeatedly turn on and off at high speed. The noise is propagated from the inverter to the motor's power transmission path. The noise is ultimately radiated from the drive shaft, which acts as an antenna. The radiated noise can affect peripheral devices such as radios.

[0005] In the device, there is a demand for reducing noise radiated from the drive shaft. [Means for solving the problem]

[0006] In one aspect of the present invention, an apparatus includes: A motor; an inverter that drives the motor; a gear unit connected downstream of the motor; a drive shaft that transmits the power of the motor transmitted from the gear device to a drive wheel; the drive shaft has a portion to which a sheet-like noise reducing material is attached, a case that houses the gear device; The drive shaft a first region inside the case that connects to the gear device; a second region connected to the drive wheel outside the case; a universal joint is provided in the second region; the universal joint has a joint member and a boot; of the second region, The joint member and the boot at least One side The sheet-like noise reducing material is Directly and all around It is pasted on. [Effects of the Invention]

[0007] According to one aspect of the present invention, noise radiated from a drive shaft can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a skeleton diagram illustrating a power transmission device. [Figure 2] FIG. 2 is a diagram showing the drive shaft 7. As shown in FIG. [Figure 3] FIG. 3 is a diagram showing the drive shaft 8. As shown in FIG. [Figure 4] FIG. 4 is a diagram showing a drive shaft 7 provided with a noise reduction sheet. [Figure 5] FIG. 5 is a diagram showing a drive shaft 8 provided with a noise reduction sheet. [Figure 6] FIG. 6 is a cross-sectional view taken along line AA in FIG. [Figure 7] FIG. 7 is a diagram showing an example of the application of the noise reduction sheet. [Figure 8] FIG. 8 is a diagram showing another example of how the noise reduction sheet is attached. [Figure 9] FIG. 9 is a diagram illustrating noise propagation in a power transmission device. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following description, a power transmission device mounted on a vehicle will be described as an example of a device according to an aspect of the present invention. The power transmission device is a device including a motor, which is a rotating electric machine, and a power transmission mechanism that transmits the power of the motor to drive wheels. The power transmission mechanism includes, for example, a gear mechanism and / or a differential gear mechanism.

[0010] In the following description, when a second element (component, part, etc.) is connected to a first element (component, part, etc.), a second element (component, part, etc.) is connected downstream of a first element (component, part, etc.), or a second element (component, part, etc.) is connected upstream of a first element (component, part, etc.), it means that the first element and the second element are connected so that power can be transmitted. The power input side is upstream, and the power output side is downstream. The first element and the second element may also be connected via another element (clutch, other gear mechanism, etc.).

[0011] "Overlapping when viewed from a predetermined direction" means that multiple elements are lined up in a predetermined direction, and is synonymous with "overlapping in a predetermined direction." Examples of the "predetermined direction" include the axial direction, radial direction, gravity direction, and vehicle travel direction (forward and backward directions). When a drawing shows multiple elements (components, parts, etc.) arranged in a specific direction, it may be assumed that the description in the specification contains a sentence explaining that they overlap when viewed from the specific direction.

[0012] "Not overlapping when viewed from a predetermined direction" and "offset when viewed from a predetermined direction" mean that multiple elements are not lined up in a predetermined direction, and are synonymous with "not overlapping in a predetermined direction" and "offset in a predetermined direction." Examples of the "predetermined direction" include the axial direction, radial direction, gravity direction, and vehicle travel direction (vehicle forward direction, vehicle backward direction). If a drawing shows that multiple elements (components, parts, etc.) are not aligned in a specified direction, it may be assumed that the description in the specification contains a sentence explaining that they do not overlap when viewed from a specified direction.

[0013] "When viewed from a predetermined direction, a first element (component, part, etc.) is located between a second element (component, part, etc.) and a third element (component, part, etc.)" means that when observed from a predetermined direction, it can be observed that the first element is located between the second element and the third element. "Predetermined direction" refers to an axial direction, a radial direction, the direction of gravity, the vehicle traveling direction (the vehicle forward direction, the vehicle backward direction), etc. For example, if the second element, the first element, and the third element are arranged in that order along the axial direction, the first element can be said to be located between the second element and the third element when viewed from the radial direction. If the drawings show that the first element is located between the second element and the third element when viewed from a predetermined direction, it can be considered that the description in the specification contains a sentence explaining that the first element is located between the second element and the third element when viewed from the predetermined direction.

[0014] In the following description, "axial direction" means the axial direction of the rotation axis of a component constituting the device. "radial direction" means the direction perpendicular to the rotation axis of a component constituting the device. "circumferential direction" means the circumferential direction around the rotation axis of a component constituting the device.

[0015] FIG. 1 is a skeleton diagram illustrating a power transmission device 1. As shown in FIG. As shown in Fig. 1, the power transmission device 1 has a motor 2, a power transmission mechanism 3, and an inverter 6. The motor 2 is driven by the inverter 6. Power generated by the rotation of the motor 2 about a rotation axis X is transmitted to the driving wheels KA and KB of the vehicle via the power transmission mechanism 3. The motor 2 is a rotating electric machine that has at least one of a motor function and a generator function.

[0016] The power transmission mechanism 3 has a gear device consisting of a planetary reduction gear 4 and a differential mechanism 5, and drive shafts 7 and 8 which serve as output shafts. The planetary reduction gear 4 is connected downstream of the motor 2. The differential mechanism 5 is connected downstream of the motor 2 via the planetary reduction gear 4. The differential mechanism 5 is disposed coaxially with the rotation axis X. The drive shafts 7 and 8 are connected downstream of the differential mechanism 5.

[0017] In the power transmission device 1, a planetary reduction gear 4, a differential mechanism 5, and drive shafts 7 and 8 are provided along a transmission path of the output rotation of the motor 2 around the rotation axis X. The output rotation of the motor 2 is transmitted to the planetary reduction gear 4 via the motor shaft 21. The planetary reduction gear 4 reduces the rotation speed and outputs it to the differential mechanism 5. Drive shafts 7 and 8 are connected to one side and the other side of the differential mechanism 5 in the direction of the rotation axis X, respectively. The differential mechanism 5 outputs the rotation input from the planetary reduction gear 4 side to the drive shafts 7 and 8.

[0018] As shown in FIG. 1, the motor 2 and the gear device (the planetary reduction gear 4 and the differential mechanism 5) are housed in a case 10. Although not shown in the drawings, the case 10 may have a partition between the motor 2 and the gear device (planetary reduction gear 4 and differential mechanism 5). The motor 2 and the gear device (planetary reduction gear 4 and differential mechanism 5) may be housed in separate cases, and the cases may be joined to form the case 10. The drive shafts 7 and 8 are each connected to the differential mechanism 5 inside the case 10. The drive shafts 7 and 8 are each connected to the left and right drive wheels KA and KB of the vehicle outside the case 10. The output rotation of the motor 2 is ultimately transmitted to the drive wheels KA and KB via the drive shafts 7 and 8.

[0019] The inverter 6 is an electronic component equipped with a smoothing capacitor, a transistor, a driver board, etc. (not shown). The inverter 6 is electrically connected to the motor 2 inside the case 10. The inverter 6 converts direct current into alternating current and supplies it to the motor 2 to drive the motor 2. The inverter 6 controls the rotation speed of the motor 2 by changing the frequency of the alternating current.

[0020] FIG. 2 is a diagram showing the drive shaft 7. As shown in FIG. As shown in FIGS. 1 and 2, the drive shaft 7 has a differential-side shaft member 71, an intermediate shaft member 73, and a drive-wheel-side shaft member 75. The differential-side shaft member 71 is located inside the case 10 as a first region 7A of the drive shaft 7.

[0021] The intermediate shaft member 73 and the drive wheel side shaft member 75 are located outside the case 10. The drive wheel side shaft member 75 is connected to the drive wheel KA so as to be able to transmit rotation. The intermediate shaft member 73 is provided between the differential side shaft member 71 and the drive wheel side shaft member 75. The intermediate shaft member 73 is connected to each of the differential side shaft member 71 and the drive wheel side shaft member 75 via universal joints 77, 78 so as to be able to transmit rotation. The intermediate shaft member 73, the drive wheel side shaft member 75 and the universal joints 77, 78 are located outside the case 10 as a second region 7B of the drive shaft 7.

[0022] As shown in FIG. 1, the differential-side shaft member 71 is disposed inside the case 10 coaxially with the rotation axis X of the motor 2. One end 71a of the differential-side shaft member 71 is connected to the differential mechanism 5 from one side in the direction of the rotation axis X (the left side in the figure). An opening 11a is provided at the end 11 on one side in the direction of the rotation axis X of the case 10. The other end 71b of the differential-side shaft member 71 in the direction of the rotation axis X is inserted through the opening 11a and connected to a universal joint 77 located near the opening 11a.

[0023] One end 73a of the intermediate shaft member 73 in the direction of the rotation axis X is connected to a universal joint 77 from the opposite side to the differential-side shaft member 71. The other end 73b of the intermediate shaft member 73 in the direction of the rotation axis X is connected to a universal joint 78. One end 75a of the drive wheel side shaft member 75 in the direction of the rotation axis X is connected to the universal joint 78 from the opposite side of the intermediate shaft member 73. The other end 75b of the drive wheel side shaft member 75 in the direction of the rotation axis X is connected to the drive wheel KA.

[0024] 2, the universal joint 77 is composed of a coupling member 771 that is connected to the intermediate shaft member 73, and a boot 775 that covers the connecting portion (not shown) between the coupling member 771 and the intermediate shaft member 73. Although not shown, the intermediate shaft member 73 is swingably connected to the inside of the coupling member 771. The boot 775 prevents leakage of lubricant sealed inside the coupling member 771 and prevents entry of foreign matter from the outside.

[0025] The universal joint 78 is composed of a coupling member 781 that connects to the intermediate shaft member 73, and a boot 785 that covers the connection portion between the coupling member 781 and the intermediate shaft member 73. Although not shown in the figure, the intermediate shaft member 73 is swingably connected to the inside of the coupling member 781. The boot 785 prevents leakage of lubricant sealed inside the coupling member 781 and prevents entry of foreign matter from the outside.

[0026] FIG. 3 is a diagram showing the drive shaft 8. As shown in FIG. As shown in FIGS. 1 and 3, the drive shaft 8 has a differential-side shaft member 81, an intermediate shaft member 83, and a drive-wheel-side shaft member 85. As shown in FIG. 1, the differential-side shaft member 81 is located inside the case 10 as a first region 8A of the drive shaft 8.

[0027] The intermediate shaft member 83 and the drive wheel side shaft member 85 are located outside the case 10. The drive wheel side shaft member 85 is connected to the drive wheel KB. The intermediate shaft member 83 is provided between the differential side shaft member 81 and the drive wheel side shaft member 85. The intermediate shaft member 83 is connected to the differential side shaft member 81 and the drive wheel side shaft member 85 via universal joints 87 and 88, respectively. The intermediate shaft member 83, the drive wheel side shaft member 85 and the universal joints 87, 88 are located outside the case 10 as a second region 8B of the drive shaft 8.

[0028] As shown in FIG. 1, the differential-side shaft member 81 is disposed inside the case 10 coaxially with the rotational axis X of the motor 2. One end 81a of the differential-side shaft member 81 in the direction of the rotational axis X is connected to the differential mechanism 5 from the other side in the direction of the rotational axis X (the right side in the figure). The differential-side shaft member 81 is inserted through the inner periphery of the motor shaft 21 inside the case 10. An opening 12a is provided at the end 12 on the other side in the direction of the rotational axis X of the case 10. The other end 81b of the differential-side shaft member 81 in the direction of the rotational axis X is inserted through the opening 12a and connected to a universal joint 87 located near the opening 12a.

[0029] One end 83a of the intermediate shaft member 83 in the direction of the rotation axis X is connected to a universal joint 87 from the opposite side to the differential-side shaft member 81. The other end 83b of the intermediate shaft member 83 in the direction of the rotation axis X is connected to a universal joint 88. One end 85a of the drive wheel side shaft member 85 in the direction of the rotation axis X is connected to the universal joint 88 from the opposite side of the intermediate shaft member 83. The other end 85b of the drive wheel side shaft member 85 in the direction of the rotation axis X is connected to the drive wheel KB.

[0030] 3, the universal joint 87 is composed of a coupling member 871 that is connected to the intermediate shaft member 83, and a boot 875 that covers the connection portion between the coupling member 871 and the intermediate shaft member 83. Although not shown in the figure, the intermediate shaft member 83 is swingably connected to the inside of the coupling member 871. The boot 875 prevents leakage of lubricant sealed inside the coupling member 871 and prevents entry of foreign matter from the outside.

[0031] The universal joint 88 is composed of a coupling member 881 that is connected to the intermediate shaft member 83, and a boot 885 that covers the connection portion between the coupling member 881 and the intermediate shaft member 83. Although not shown in the drawings, the intermediate shaft member 83 is swingably connected to the inside of the coupling member 881. The boot 885 prevents leakage of lubricant sealed inside the coupling member 881 and prevents entry of foreign matter from the outside.

[0032] FIG. 4 is a diagram showing the drive shaft 7 provided with a noise reduction sheet. FIG. 5 is a diagram showing a drive shaft 8 provided with a noise reduction sheet. FIG. 6 is a cross-sectional view taken along line AA in FIG. 4 to 6, the noise reducing sheet 9 is shown with cross-hatching for ease of understanding. Also, in Fig. 6, the thicknesses of the noise reducing sheet 9 and adhesive AH are exaggerated for ease of understanding. 4 and 5, the drive shafts 7 and 8 have portions that are covered with noise reducing sheets 9 (noise reducing materials). In other words, the drive shafts 7 and 8 have portions that overlap with the noise reducing sheets 9 when viewed radially from their respective axes. 4, the second region 7B of the drive shaft 7 is covered with a noise reducing sheet 9. Specifically, the surfaces of the intermediate shaft member 73, the drive wheel side shaft member 75, and the universal joints 77 and 78 are covered with the noise reducing sheet 9.

[0033] 5, the second region 8B of the drive shaft 8 is also covered with the noise reducing sheet 9. Specifically, the surfaces of the intermediate shaft member 83, the drive wheel side shaft member 85, and the universal joints 87 and 88 are covered with the noise reducing sheet 9. As described above, the second regions 7B, 8B of the drive shafts 7, 8 are regions located outside the case 10 (see FIG. 1).

[0034] The noise reducing sheet 9 has the property of converting high frequency noise into heat, and is provided to reduce noise. The noise reduction sheet 9 is, for example, a resin film or film containing a magnetic substance, a conductive material, etc. Examples of the conductive material include metal, carbon, graphite, etc. The noise reduction sheet 9 may be a woven, knitted, nonwoven, or other fiber coated with a conductive material, or may be any of the above-mentioned fibers carrying a magnetic substance or a conductive material.

[0035] 6, the noise reducing sheet 9 is attached so as to cover the surface of the drive shaft 7. The noise reducing sheet 9 can be adhered to the surface of the drive shaft 7 in close contact with it using, for example, adhesive AH. 6 shows the intermediate shaft member 73, the noise reducing sheet 9 can also be attached using adhesive AH to the drive wheel side shaft member 75 and the universal joints 77, 78. Furthermore, although not shown in the figures, the noise reducing sheet 9 can also be attached using adhesive AH to the drive shaft 8 in the same way.

[0036] FIG. 7 is a diagram showing an example of the application of the noise reduction sheet. FIG. 8 is a diagram showing another example of how the noise reduction sheet is attached. 7 and 8 show only the second region 7B of the drive shaft 7, and do not show the adhesive. While FIGS. 7 and 8 show an example in which the noise reducing sheet 9 is attached to the intermediate shaft member 73 of the drive shaft 7, it can also be attached to other locations in the same way. The noise reducing sheet 9 can also be attached to the drive shaft 8 in the same way. In the following description, the noise reducing sheet 9 will also be referred to as noise reducing sheet 9A or noise reducing sheet 9B as necessary.

[0037] As shown in Fig. 7, the noise reducing sheet 9A may be, for example, strip-shaped. The strip-shaped noise reducing sheet 9A may be spirally wound around the surface of the intermediate shaft member 73 with the phases shifted. Fig. 7 shows an example in which the noise reducing sheet 9A is attached to the intermediate shaft member 73, but the strip-shaped noise reducing sheet 9A can also be wrapped around the universal joints 77 and 78, for example. This allows the noise reducing sheet 9A to be attached in close contact with the universal joints 77 and 78, which have many irregularities on their surfaces.

[0038] 8, the noise reduction sheet 9B may be rectangular, for example. The rectangular noise reduction sheet 9B can be attached to the surface of the intermediate shaft member 73 with its longitudinal direction aligned with the axis X1 of the intermediate shaft member 73 and one end 91 and the other end 92 in the lateral direction abutting on the surface of the intermediate shaft member 73. Alternatively, the noise reduction sheet 9B may be attached with its one end 91 overlapping its other end 92.

[0039] The intermediate shaft member 73 has a relatively small surface irregularity and a long shaft length. Therefore, by using a rectangular noise reducing sheet 9B, the noise reducing sheet 9B can be attached efficiently. Similarly, a rectangular noise reducing sheet 9B can be attached efficiently to the drive wheel side shaft member 75. The shape of the noise reduction sheet 9 and the location where the noise reduction sheet 9 is attached are not limited to the examples shown in Figures 7 and 8. The shape of the noise reduction sheet 9 and the location where the noise reduction sheet 9 is attached can be changed as appropriate.

[0040] Fig. 9 is a diagram illustrating the propagation of noise in the power transmission device 1. In Fig. 9, noise is indicated by hatched arrows. As described above, the inverter 6 has transistors, which are switching elements. When the transistors repeatedly turn on and off at high speed during control of the motor 2, ringing, a type of high-frequency noise, occurs. This noise is propagated from the inverter 6, which is the noise source, to the power transmission path of the motor 2. In other words, the noise is propagated via the motor 2, motor shaft 21, planetary reduction gear 4, and differential mechanism 5, and ultimately to the drive shafts 7 and 8.

[0041] The drive shafts 7, 8 act as antennas. Therefore, noise propagated to the drive shafts 7, 8 is radiated into the air from the drive shafts 7, 8. The noise radiated into the air may affect vehicle equipment such as an AM radio or wireless communication equipment installed in the vehicle. In particular, since the second regions 7B, 8B (see FIGS. 2 and 3) of the drive shafts 7, 8 are located outside the case 10, there is a high possibility that the radiated noise will affect the vehicle equipment. Here, the vehicle equipment may be, for example, electronic equipment installed in the vehicle equipped with the power transmission device 1.

[0042] One way to reduce radiated noise is to provide an earth connection on the power transmission path of the motor 2. The earth connection is, for example, a sliding brush that comes into sliding contact with shaft elements (motor shaft 21, drive shafts 7 and 8, etc.) on the power transmission path. The earth connection is connected to the case 10, which is connected to the vehicle body by a ground line. By grounding the power transmission path via the earth connection and the case 10 to the vehicle body, it is possible to reduce noise radiation from the drive shafts 7 and 8.

[0043] The earth connection body is preferably located away from the inverter 6, which is a noise source. Although the second regions 7B, 8B of the drive shafts 7, 8 are away from the inverter 6, the intermediate shaft members 73, 83 and the drive-wheel-side shaft members 75, 85 oscillate. This makes it difficult to install the earth connection body, which is a sliding brush, so that it is in constant contact with these members. Furthermore, the earth connection body must be installed in a dry environment, but the second regions 7B, 8B located outside the case 10 may be exposed to muddy water, etc., so if the earth connection body is installed in the second regions 7B, 8B, it is difficult to keep the earth connection body in a dry environment.

[0044] If the earth connection body is provided inside the case 10, the earth connection body is a thick component, which tends to restrict the layout inside the case 10. Furthermore, oil is stored inside the case 10 to lubricate the rotating parts. In order to install the earth connection body in a dry environment, a separate chamber sealed to prevent oil from entering the case 10 must be provided inside the case 10. However, providing a separate chamber inside the case 10 may result in an increase in the size of the case 10. Furthermore, since the earth connection body must be in contact with a metal part, this may result in an increase in the dimensions of the motor shaft 21 or the differential-side shaft member 71. As such, the layout of the earth connection body is likely to be restricted, which may also lead to an increase in the size of the power transmission device 1.

[0045] On the other hand, the noise reducing sheet 9 is a thin member and can be provided in close contact with the surfaces of the drive shafts 7, 8. Therefore, the noise reducing sheet 9 has fewer layout restrictions and is less likely to lead to an increase in the size of the power transmission device 1. Furthermore, because the noise reducing sheet 9 does not need to be installed in a dry environment, it can be provided in the second regions 7B, 8B of the drive shafts 7, 8 located outside the case 10. Because the noise reducing sheet 9 can be attached with adhesive AH, it can also be provided on the oscillating intermediate shaft member 73 and drive wheel side shaft member 75. As described above, the drive shafts 7, 8 act as antennas and radiate noise, which affects vehicle equipment. Furthermore, because the second regions 7B, 8B of the drive shafts 7, 8 are exposed to the outside of the case 10, noise radiated from the second regions 7B, 8B is likely to affect vehicle equipment. By providing the noise reduction sheet 9 so as to cover the second regions 7B, 8B, it is possible to reduce noise that is likely to affect vehicle equipment.

[0046] Examples of devices according to certain aspects of the present invention are listed below. (1) The power transmission device 1 (device) is Motor 2 and an inverter 6 that drives the motor 2; a planetary reduction gear 4 and a differential mechanism 5 (gear device) connected downstream of the motor 2; The vehicle has drive shafts 7 and 8 that transmit the power of the motor 2 transmitted from the planetary reduction gear 4 and the differential mechanism 5 to the drive wheels KA and KB. The drive shafts 7 and 8 have portions (second regions 7B and 8B) covered with a noise reducing sheet 9 (noise reducing material).

[0047] With this configuration, the noise radiated from the drive shafts 7 and 8 can be reduced. The power transmission device 1 includes a motor 2, a gear device, drive shafts 7 and 8, and drive wheels KA and KB arranged along a power transmission path. The motor 2 is driven by an inverter 6. The power (rotational force) generated by the motor 2 is transmitted to the drive wheels KA and KB via the gear device and drive shafts 7 and 8. High-frequency noise generated by the inverter 6 propagates along the power transmission path of the motor 2 to the drive shafts 7 and 8. The propagated noise is ultimately radiated from the drive shafts 7 and 8, which act as antennas. The noise radiated from the drive shafts 7 and 8 may affect vehicle equipment such as AM radios.

[0048] By providing portions of the drive shafts 7, 8 that are covered with noise reducing material, it is possible to reduce noise emitted from the drive shafts 7, 8. Furthermore, by making the noise reducing material into a sheet-like noise reducing sheet 9, it can be easily attached by wrapping it around the drive shafts 7, 8. Furthermore, the noise reducing sheet 9 requires little space for installation, which helps prevent an increase in the size of the device. Furthermore, since the noise reducing sheet 9 is less restricted by the installation environment, such as a dry environment, it allows for greater freedom in layout.

[0049] (2) The drive shaft of the power transmission device 1 includes a drive shaft 7 (first drive shaft) and a drive shaft 8 (second drive shaft). It is preferable that the noise reducing sheet 9 be provided on both the drive shaft 7 and the drive shaft 8 .

[0050] The power transmission device 1 includes two drive shafts 7 and 8 for transmitting power to the left and right drive wheels KA and KB, respectively. Each of the two drive shafts 7 and 8 acts as an antenna and radiates noise. Therefore, by providing a noise reduction sheet 9 on at least one of the two drive shafts 7 and 8, and preferably on both, the noise reduction effect (the effect of reducing radiated noise) can be improved.

[0051] (3) The power transmission device 1 has a case 10 that houses the planetary reduction gear 4 and the differential mechanism 5 (gear device). The drive shafts 7, 8 have first regions 7A, 8A that connect to the differential mechanism 5 of the gear device inside the case 10. The first regions 7A, 8A have differential-side shaft members 71, 81. The drive shafts 7, 8 have second regions 7B, 8B that connect to the drive wheels KA, KB outside the case 10. The second region 7B has an intermediate shaft member 73, a drive wheel side shaft member 75, and universal joints 77 and 78. The second region 8B has an intermediate shaft member 83, a drive wheel side shaft member 85, and universal joints 87 and 88. The second regions 7B, 8B of the drive shafts 7, 8 may have portions covered with the noise reducing sheets 9.

[0052] Because the second regions 7B, 8B of the drive shafts 7, 8 are located outside the case 10, noise propagated to the drive shafts 7, 8 is likely to be radiated from the exposed portions of the second regions 7B, 8B toward the outside of the power transmission device 1. By providing the noise reduction sheets 9 in the second regions 7B, 8B, the noise reduction effect can be improved. Furthermore, the second areas 7B, 8B of the drive shafts 7, 8 are located outside the case 10 and may be exposed to muddy water, etc. The noise reducing sheet 9 does not need to be used in a dry environment. Therefore, even if the noise reducing sheet 9 is provided in the second areas 7B, 8B, which are not necessarily in a dry environment, it can still exhibit its noise reduction effect. Furthermore, because the noise reducing sheet 9 is in sheet form, it can be wrapped around the surfaces of the drive shafts 7, 8. Therefore, for example, the intermediate shaft members 73, 83 of the second regions 7B, 8B are members that oscillate when the vehicle is running, and the noise reducing sheet 9 can also be provided on the intermediate shaft members 73, 83, which are oscillating members, and on the connecting members between these intermediate shaft members 73, 83. The noise reducing sheet 9 has a high degree of freedom in installation, so it can be easily installed in locations where it is desired to achieve noise reduction effects. Although the example in which the entire second areas 7B, 8B are covered with the noise reducing sheet 9 has been described, a portion of the second areas 7B, 8B may be covered with the noise reducing sheet 9.

[0053] (4) It is preferable that the noise reduction sheet 9 be provided in close contact with the drive shafts 7 and 8.

[0054] If there is an air gap between the drive shafts 7, 8 and the noise reduction sheet 9, this may affect the noise reduction effect. By closely adhering the noise reduction sheet 9 to the surfaces of the drive shafts 7, 8, noise can be reduced more effectively.

[0055] (5) The noise reducing sheet 9 can be attached to the drive shafts 7, 8 by, for example, adhesive AH.

[0056] By using the adhesive AH, the noise reducing sheet 9 can be easily attached to the drive shafts 7, 8.

[0057] The noise reducing material is not limited to a sheet-like material, and may be, for example, a powdered magnetic material, conductive material, or the like, directly applied or sprayed onto the surfaces of the drive shafts 7 and 8.

[0058] In the above example, the noise reducing sheet 9 is attached to the drive shafts 7, 8 using adhesive AH. However, the installation manner of the noise reducing sheet 9 is not limited to this. For example, the noise reducing sheet 9 may be attached to the drive shafts 7, 8 using double-sided tape. The noise reducing sheet 9 may also be adhered to the surfaces of the drive shafts 7, 8 by vapor deposition or other methods.

[0059] The above description is of an example in which the noise reducing sheet 9 is provided in the second regions 7B and 8B of the drive shafts 7 and 8. However, the location of the noise reducing sheet 9 is not limited to this example. The noise reducing sheet 9 can also be provided in the first regions 7A and 8A of the drive shafts 7 and 8.

[0060] In this embodiment, the device is applied to a power transmission device 1 mounted on a vehicle, but the present invention is not limited to this embodiment, and the device can be applied to devices other than vehicles. Furthermore, when multiple examples and modified examples are described in this embodiment, they may be combined in any desired manner.

[0061] Although the embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configuration of the above embodiment. Appropriate modifications are possible within the scope of the technical concept of the invention. [Explanation of symbols]

[0062] 1: Power transmission device (device) 2: Motor 4: Planetary reduction gear (gear device) 5: Differential mechanism (gear device) 6: Inverter 7: Drive shaft (first drive shaft) 8: Drive shaft (second drive shaft) 7A, 8A: First area 7B, 8B: Second area 71, 81: Differential side shaft member 73, 83: Intermediate shaft member 75, 85: Drive wheel side shaft member 77, 78: Universal joint 9: Noise reduction sheet (noise reduction material) 10: Case KA, KB: Drive wheels

Claims

1. A motor; an inverter that drives the motor; a gear unit connected downstream of the motor; a drive shaft that transmits the power of the motor transmitted from the gear device to a drive wheel; the drive shaft has a portion to which a sheet-like noise reducing material is attached, a case that houses the gear device; The drive shaft a first region within the case that connects to the gear device; a second region connected to the drive wheel outside the case; a universal joint is provided in the second region; the universal joint has a joint member and a boot; The device, wherein the sheet-like noise reducing material is attached directly and over the entire periphery of a portion of the second region that includes at least one of the joint member and the boot.

2. In claim 1, the drive shafts include a first drive shaft and a second drive shaft; The device includes a portion on each of the first drive shaft and the second drive shaft where the sheet-like noise reducing material is attached.

3. In claim 1 or 2, The sheet-like noise reducing material is attached to the drive shaft with an adhesive.

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