Vehicle power transmission device

Abstract

To provide a vehicle power transmission device capable of reducing a high frequency component of electromagnetic noise.SOLUTION: A vehicle power transmission device 101 includes a plurality of rotating shafts S1, S2, S3, and S4 including a rotating machine shaft S1 of a rotating machine, a plurality of power transmission units 16, 24, and 25 in which power is transmitted between the plurality of rotation axes S1, S2, S3, and S4, and a grounding mechanism 14, and in the rotating machine shaft S1 which is a target rotating shaft, a shaft end portion S1a which is a grounding portion located in a region from the output side of the rotating machine shaft S1 in the portion connected to a power transmission path A to the downstream side of the power transmission path A is grounded to a vehicle body 2 of a vehicle 1 via the ground mechanism 14.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a power transmission device for a vehicle. [Background technology]

[0002] It has been known that in electric vehicles, inverter noise caused by the inverter propagates along the power transmission path that uses the motor as a power source. This inverter noise is transmitted, for example, to the motor rotor via the power cable and the motor coil, and then from the motor rotor via the drive shaft to the suspension insulated by the tire. The cause of the transmission of this inverter noise is the generation of high-frequency components of the shaft voltage in the rotating shaft on the power transmission path. When the high-frequency components of this shaft voltage propagate along the power transmission path to the drive shaft, it causes electromagnetic noise (radio noise) that affects radio reception.

[0003] The following Patent Document 1 discloses an electromagnetic noise suppression device for an electric vehicle. This electromagnetic noise suppression device is equipped with a grounding structure that grounds the rotating machine shaft by means of a brush, oil seal, or the like in order to reduce electromagnetic noise caused by shaft voltage generated in the rotating machine shaft of an electric motor. This grounding structure is configured so that, when the reducer side of the rotating machine shaft is the output side, grounding is performed at a grounding position on the non-output side, which is the opposite side to the output side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-244180 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the grounding structure disclosed in Patent Document 1 is adopted, it is difficult to suppress the high-frequency components of the shaft voltage, which can cause a problem that the high-frequency components of electromagnetic noise cannot be reduced. The causes of this include leakage of the high-frequency components of the shaft voltage due to the inductance of the rotating shaft, and an increase in impedance in the high-frequency band due to the inductance of the springs and conductors that make up the grounding structure.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a power transmission device for a vehicle that can reduce high-frequency components of electromagnetic noise. [Means for solving the problem]

[0007] One aspect of the present invention is A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), A plurality of rotating shafts (S1, S2, S3, S4) including a rotating machine shaft (S1) of the rotating machine; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, respectively; A grounding mechanism (14, 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14I), Equipped with The rotating machine shaft has an output shaft end (S1a) located on the power transmission path. A vehicle power transmission device (101, 102, 103, 104, 105) that is grounded to the vehicle body (2) via the grounding mechanism. , 109,115,116,117,118,119,120,121,126,127), is located.

[0008] Another aspect of the present invention is A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), Multiple rotation axes (S1, S2, S3, S4) a plurality of bearings (15, 21, 22, 23) for rotatably supporting the plurality of rotating shafts; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, respectively; a grounding mechanism (14) for grounding at least one of the plurality of rotating shafts, that is, a target rotating shaft, to a body (2) of the vehicle; Equipped with a reducer (20) constituting the power transmission path is provided, and a reducer shaft (S2, S3) of the reducer is the symmetric rotation shaft, a vehicle power transmission device (110, 111, 112, 113, 114, 122, 123, 124, 125), wherein the plurality of bearings include an insulating bearing having an outer ring (15a), an inner ring (15b), and a plurality of rolling elements (15c) held between the outer ring and the inner ring so as to be capable of rolling, and the insulating bearing is configured such that at least one of the outer ring, the inner ring, and the plurality of rolling elements is made of an electrically insulating material; is located. Further, another aspect of the present invention is A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), A plurality of rotating shafts (S1, S2, S3, S4) including a rotating machine shaft (S1) of the rotating machine; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, respectively; A grounding mechanism (14, 14C, 14D, 14E, 14F, 14H, 14I), Equipped with a target rotating shaft, which is at least one of the plurality of rotating shafts, has a grounding portion, which is located within a region from an output side of the rotating shaft to a downstream side of the power transmission path, among a portion connected to the power transmission path, and is grounded to a body (2) of the vehicle via the grounding mechanism; a power transmission device for a vehicle (101, 102, 103, 104, 105, 106, 107, 108, 117, 118, 119, 120, 126, 127), wherein the grounding mechanism includes a conductive brush (14a), a first elastic body (14b) that applies pressure to the brush so as to press it against the circumferential surface of the target rotating shaft, and a conductive second elastic body (14g) that is interposed between the brush and a ground (10b), and the second elastic body electrically connects the brush and the ground and elastically biases the brush and the ground in a direction separating them from each other; is located. Effect of the Invention

[0009] In one aspect of the above, the vehicle power transmission device includes a plurality of rotating shafts, a plurality of power transmission units, and a grounding mechanism. Power is transmitted between the plurality of rotating shafts in each of the plurality of power transmission units. In each power transmission unit, power is transmitted between one rotating shaft and another rotating shaft. A target rotating shaft, which is at least one of the plurality of rotating shafts, has a grounding portion located within a region from the output side of the rotating shaft to the downstream side of the power transmission path among portions connected to the power transmission path, and the grounding portion is grounded to a vehicle body via the grounding mechanism.

[0010] Here, when the non-output side of the rotating machine shaft is grounded by a grounding mechanism, it is difficult to prevent the high-frequency components of the shaft voltage caused by the inverter from leaking downstream of the power transmission path. Therefore, by grounding the target rotating shaft by the above-mentioned grounding part, it is possible to prevent the high-frequency components of the shaft voltage from leaking downstream of the power transmission path, and the high-frequency components of the electromagnetic noise can be reduced.

[0011] In the above-mentioned alternative embodiment, the vehicle power transmission device includes a plurality of rotating shafts, a plurality of bearings, and a plurality of power transmission units. Power is transmitted between the plurality of rotating shafts in each of the plurality of power transmission units. In each of the power transmission units, power is transmitted between one rotating shaft and another rotating shaft. The plurality of rotating shafts are rotatably supported by a plurality of bearings. The plurality of bearings include an insulating bearing in which at least one of the outer ring, the inner ring, and the plurality of rolling elements is made of an electrically insulating material. Such an insulating bearing is effective in preventing the occurrence of dielectric breakdown of the bearing. This makes it possible to suppress leakage of high-frequency components of the shaft voltage to the downstream side of the power transmission path, thereby reducing the high-frequency components of the electromagnetic noise.

[0012] As described above, according to the above aspects, it is possible to provide a power transmission device for a vehicle that can reduce high frequency components of electromagnetic noise.

[0013] In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief description of the drawings]

[0014] [Figure 1] 1 is a plan view showing an overview of a vehicle according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a vehicle power transmission device according to a first embodiment. [Diagram 3] 1 is a cross-sectional view taken along an axial direction of a peripheral portion of a rotating machine in a vehicle power transmission device according to a first embodiment. [Figure 4] FIG. 2 is a diagram showing an equivalent circuit on the upstream side of the power transmission path in FIG. 1. [Diagram 5] FIG. 5 is a diagram showing a state in which electromagnetic noise propagates in FIG. 4. [Figure 6] FIG. 11 is a plan view of a second embodiment corresponding to FIG. [Figure 7] FIG. 11 is a plan view of a third embodiment corresponding to FIG. [Figure 8]FIG. 11 is a plan view of a fourth embodiment corresponding to FIG. [Figure 9] FIG. 11 is a plan view corresponding to FIG. 1 according to a fifth embodiment. [Figure 10] FIG. 13 is a schematic diagram of a vehicle power transmission device according to a sixth embodiment. [Figure 11] FIG. 13 is a schematic diagram of a vehicle power transmission device according to a seventh embodiment. [Figure 12] FIG. 13 is a schematic diagram of a vehicle power transmission device according to an eighth embodiment. [Figure 13] 13 is a cross-sectional view corresponding to FIG. 3 of a vehicle power transmission device according to a ninth embodiment. [Figure 14] FIG. 14 is a cross-sectional view of the grounding mechanism in FIG. [Figure 15] FIG. 16 is a schematic diagram of a vehicle power transmission device according to a tenth embodiment. [Figure 16] 16 is a cross-sectional view of a bearing applied to a rotating machine shaft of the rotating machine in FIG. 15 in the axial direction. [Figure 17] FIG. 13 is a diagram showing a state of dielectric breakdown of a bearing in an equivalent circuit on the upstream side of a power transmission path as a comparative example. [Figure 18] 16 is a diagram showing a path of a shaft voltage in an equivalent circuit on the upstream side of the power transmission path in FIG. 15. [Figure 19] FIG. 23 is a schematic diagram of a vehicle power transmission device according to an eleventh embodiment. [Figure 20] FIG. 23 is a schematic diagram of a vehicle power transmission device according to a twelfth embodiment. [Figure 21] FIG. 23 is a schematic diagram of a vehicle power transmission device according to a thirteenth embodiment. [Figure 22] FIG. 23 is a schematic diagram of a vehicle power transmission device according to a fourteenth embodiment. [Diagram 23] FIG. 23 is a cross-sectional view of a ground contact mechanism for a vehicle power transmission device according to a fifteenth embodiment. [Figure 24] FIG. 24 is a perspective view of the barb spring in FIG. 23. [Diagram 25] FIG. 23 is a cross-sectional view of a ground contact mechanism for a vehicle power transmission device according to a sixteenth embodiment. [Figure 26] FIG. 23 is a cross-sectional view of a ground contact mechanism for a vehicle power transmission device according to a seventeenth embodiment. [Figure 27] FIG. 23 is a cross-sectional view of a ground contact mechanism for a vehicle power transmission device according to an eighteenth embodiment. [Figure 28]FIG. 23 is a cross-sectional view corresponding to FIG. 3 of a vehicle power transmission device according to a nineteenth embodiment. [Figure 29] A cross-sectional view taken along line XXIX-XXIX in Figure 28. [Diagram 30] 29A and 29B are cross-sectional views of a ground contact mechanism for a vehicle power transmission device according to a twentieth embodiment of the present invention. [Diagram 31] 31 is a cross-sectional view showing the grounding mechanism of FIG. 30 when the rotor shaft rotates in a first rotation direction. [Diagram 32] 31 is a cross-sectional view showing the grounding mechanism of FIG. 30 when the rotor shaft rotates in a first rotation direction. [Diagram 33] 29A and 29B are cross-sectional views of a ground contact mechanism for a vehicle power transmission device according to a twenty-first embodiment. [Diagram 34] FIG. 22 is a cross-sectional view of a rotating machine in a vehicle power transmission device according to a twenty-second embodiment. [Diagram 35] A cross-sectional view taken along line XXXV-XXXV in Figure 34. [Diagram 36] FIG. 23 is a cross-sectional view of a rotating machine in a vehicle power transmission device according to a twenty-third embodiment. [Figure 37] A cross-sectional view taken along line XXXVII-XXXVII in Figure 36. [Figure 38] FIG. 25 is a cross-sectional view of a rotating machine in a vehicle power transmission device according to a twenty-fourth embodiment. [Figure 39] FIG. 25 is a cross-sectional view of a rotating machine in a vehicle power transmission device according to a twenty-fifth embodiment. [Diagram 40] FIG. 26 is a cross-sectional view corresponding to FIG. 3 of a vehicle power transmission device according to a twenty-sixth embodiment. [Diagram 41] An enlarged view of the grounding mechanism in Figure 40. [Diagram 42] FIG. 42 is a cross-sectional view taken along line XLII-XLII in FIG. [Diagram 43] 42 , showing a ground contact mechanism for a vehicle power transmission device according to a twenty-seventh embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of a power conversion device will be described with reference to the drawings. The present embodiment is typically suitable for use as an in-vehicle power conversion device that is mounted on a vehicle such as an electric vehicle or a hybrid vehicle and performs power conversion between DC power and AC power.

[0016] In this specification, unless otherwise specified, a first direction which is the axial direction of the rotation shaft is indicated by arrow X, a second direction which is the radial direction of the rotation shaft is indicated by arrow Y, and a third direction which is perpendicular to both the first and second directions is indicated by arrow Z.

[0017] (Embodiment 1) As shown in FIG. 1, a vehicle 1 according to the first embodiment is an electric vehicle including a vehicle body 2, left and right drive wheels 3, an inverter 4, a battery 5, a rotating machine 10, and a reduction gear 20.

[0018] The rotating machine 10 is configured as a motor generator having both the functions of a motor and a generator. The rotating machine 10 includes a rotating machine shaft (hereinafter also referred to as a "rotating shaft") S1 which is a motor shaft, a rotor 11 which serves as a rotor that rotates integrally with the rotating machine shaft S1, and a stator 12 which serves as a stator around which a coil 13 is wound. A bearing (bearing 15 described below) which rotatably supports the rotating machine S1 is electrically connected to the vehicle body 2 via a grounding mechanism 14 and a case 10a (see FIG. 3). The rotating machine 10 is controlled by an inverter 4.

[0019] The inverter 4 is a semiconductor module having a plurality of switching elements (not shown) connected to any of the electrodes of the three phases (U phase, V phase, W phase) of the rotating machine 10, and serves to perform power conversion. The inverter 4 is electrically connected to the coil 13 of the rotating machine 10, and is also electrically connected to the battery 5 via a harness 6.

[0020] The reducer 20 is for transmitting the driving force of the rotating machine 10 to the driving wheels 3. The reducer 20 is provided with three rotating shafts S2, S3, and S4. Among the three rotating shafts S2, S3, and S4, the rotating shaft S2 is provided at the most upstream of a power transmission path A formed with the rotating machine 10 side on the upstream side and the driving wheels 3 side on the downstream side. The rotating shaft S3 is provided between the rotating shaft S2 and the rotating shaft S4 in the power transmission path A. The rotating shaft S4 is provided so as to connect the differential gear G5 and the two driving wheels 3, and is configured as a drive shaft that drives the driving wheels 3. This reducer 20 is also called a transmission.

[0021] 2, a power transmission device for a vehicle (hereinafter, simply referred to as a "power transmission device") 100 of the first embodiment is a device that transmits the driving force of a rotating machine 10 controlled by an inverter 4 to driving wheels 3 of a vehicle 1 through a power transmission path A. The power transmission path A is formed by a reduction gear 20.

[0022] The power transmission device 100 includes four rotating shafts S1, S2, S3, and S4, four bearings 15, 21, 22, and 23, three power transmission parts 16, 24, and 25, and a grounding mechanism .

[0023] A rotor shaft S1 of the rotor 10 extends in a first direction X, and is configured to be rotatably supported by two bearings 15 that serve as bearings.

[0024] The rotating shaft S2 extends in the first direction X on the axis of the rotating machine shaft S1 and is rotatably supported by two bearings 21. The rotating shaft S2 is connected to the rotating machine shaft S1 via a power transmission unit 16 and is configured to rotate integrally with the rotating machine shaft S1. A first gear G1 is provided on the axial circumference of the rotating shaft S2.

[0025] The power transmission unit 16 is formed by a spline connection. Although not shown, the spline connection is a form in which one of the rotating shafts S1 and S2 is a spline shaft, and external teeth provided on the axial circumference of the spline shaft are inserted into a spline hole provided on the shaft end of the other of the rotating shafts S1 and S2 and engage with internal teeth, thereby connecting the rotating shafts S1 and S2 to rotate together. This type of spline connection is a connection structure that does not have electrostatic capacitance, as opposed to a connection structure that has electrostatic capacitance such as a power transmission unit using gear engagement.

[0026] The rotating shaft S3 extends in the first direction X in a position parallel to the rotating shaft S2, and is rotatably supported by two bearings 22. A second gear G2 that meshes with the first gear G1 of the rotating shaft S2, and a third gear G3 that is disposed parallel to the second gear G2 are provided around the circumference of the rotating shaft S3. Therefore, the rotating shaft S2 and the rotating shaft S3 are connected to each other via a power transmission unit 24 that is an engagement unit that utilizes gear engagement between the first gear G1 and the second gear G2.

[0027] The rotating shaft S4 extends in the first direction X in a position parallel to the rotating shaft S3, and is rotatably supported by two bearings 23. A fourth gear G4 that meshes with the third gear G3 of the rotating shaft S3 is provided on the axial circumference of the rotating shaft S4. Therefore, the rotating shafts S3 and S4 are connected to each other via a power transmission unit 25 that is an engagement unit that utilizes gear engagement between the third gear G3 and the fourth gear G4.

[0028] Both of the two power transmission units 24, 25 utilize gear engagement and have capacitance, unlike the power transmission unit 16 that utilizes spline engagement. That is, in each of the two power transmission units 24, 25, a state occurs in which a large capacitance is formed between the two meshing gears. The two rotating shafts S1, S2 are upstream rotating shafts that are located upstream of the power transmission units 24, 25 in the power transmission path A (see FIG. 1) among the three power transmission units 16, 24, 25.

[0029] In the power transmission path A, the three power transmission units 16, 24, and 25 are configured to mechanically transmit the driving force of the rotating machine 10 to a rotating shaft (drive shaft) S4 via four gears G1, G2, and G3.

[0030] 2 and 3, in this embodiment, the grounding mechanism 14 is configured to electrically connect an output side shaft end portion S1a of the rotating machine shaft S1 of the rotating machine 10 to the body 2 of the vehicle 1 via the case 10a, with the rotating machine shaft S1 being the symmetric rotating shaft. If necessary, at least one of the four rotating shafts S1, S2, S3, and S4 may be the symmetric rotating shaft.

[0031] Here, the shaft end S1a is the shaft end on the reducer 20 side of both shaft ends S1a, S1b of the rotating machine shaft S1 in the first direction X, and is a portion located on the power transmission path A. Therefore, the shaft end S1a is a grounding portion located in the region from the output side of the rotating machine shaft S1 to the downstream side of the power transmission path A among the portions connected to the power transmission path A, and this grounding portion is grounded to the case 10a via the grounding mechanism 14.

[0032] The "portion connected to power transmission path A" includes, among the portions of the target rotating shaft, a portion located on power transmission path A (hereinafter referred to as the "first portion"), as well as a portion extending from this first portion in a direction away from power transmission path A, which is not located on power transmission path A, and is outside of power transmission path A (hereinafter referred to as the "second portion") For this reason, the first portion of the target rotating shaft may be grounded via the grounding mechanism 14, or the second portion of the target rotating shaft may be grounded via the grounding mechanism 14.

[0033] 3, the grounding mechanism 14 is interposed between a metal case 10a on the rotating machine 10 side and a metal case 20a on the reducer 20 side. The grounding mechanism 14 includes a conductive brush 14a, a spring 14b as an elastic body that applies pressure to the brush 14a so as to press it against the circumferential surface of the shaft end portion S1a of the rotating machine shaft S1 in the second direction Y, and a metal housing 14c that accommodates the brush 14a and the spring 14b.

[0034] Here, the equivalent circuit of the power transmission path A in Fig. 1 up to the shaft S2 is shown by an equivalent circuit as shown in Fig. 4. In this equivalent circuit, the grounding mechanism 14 can prevent the high-frequency component of the shaft voltage generated in the rotating machine shaft S1 during switching control of the inverter 4 from leaking downstream of the power transmission path A. At this time, the high-frequency component of the electromagnetic noise (inverter noise) generated by the high-frequency component of the shaft voltage (specifically, the pulse-like shaft voltage that remains after grounding due to the switching control of the inverter 4) propagates through noise propagation path B, which does not propagate downstream of the power transmission path A, as shown in Fig. 5.

[0035] According to the power transmission device 100 of embodiment 1, the shaft end portion S1a of the rotating machine shaft S1 is used as a grounding portion, and this grounding portion is grounded to the vehicle body 2 by the grounding mechanism 14, so that it is possible to suppress the high-frequency components of the shaft voltage from leaking to the downstream side of the power transmission path A, thereby reducing the high-frequency components of the electromagnetic noise.

[0036] Next, other embodiments related to the above-mentioned embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in embodiment 1 are given the same reference numerals, and the description of the same elements will be omitted.

[0037] (Embodiment 2) As shown in FIG. 6, a power transmission device 102 of the second embodiment differs from the power transmission device 101 of the first embodiment in the configuration of the reducer 20.

[0038] The reducer 20 of the power transmission device 102 is provided with two rotating shafts S2 and S4, while a rotating shaft corresponding to the rotating shaft S3 (see FIG. 2) of the first embodiment is omitted. The reducer 20 is configured such that a gear G1 provided on the rotating shaft S2 and a gear G4 provided on the rotating shaft S4 mesh with each other.

[0039] The other configurations are the same as those in the first embodiment.

[0040] According to the power transmission device 102 of the second embodiment, the structure of the reducer 20 can be simplified compared to the first embodiment.

[0041] In addition, the same effects as those of the first embodiment are achieved.

[0042] (Embodiment 3) As shown in FIG. 7, the power transmission device 103 of the third embodiment differs from the power transmission device 101 of the first embodiment in that the rotating machine 10 is directly connected to the rotating shaft S4.

[0043] The rotating machine shaft S1 of the rotating machine 10 has both shaft ends S1a, S1b connected to the rotating shaft S4 via planetary gears G5. A grounding mechanism 14 is provided at each of both shaft ends S1a of the rotating machine shaft S1. In this case, two grounding mechanisms 14 are used.

[0044] The other configurations are the same as those in the first embodiment.

[0045] According to the power transmission device 103 of the third embodiment, when the power transmission path A is configured using the planetary gear G5, it is possible to suppress high-frequency components of the shaft voltage from leaking to the downstream side of the power transmission path A.

[0046] In addition, the same effects as those of the first embodiment are achieved.

[0047] (Embodiment 4) 8, the power transmission device 104 of the fourth embodiment differs from the power transmission device 101 of the first embodiment in that the rotating machine 10 is directly connected to the rotating shaft S4. In this power transmission device 104, the rotating shaft S4 is coupled to both ends S1a, S1b of the rotating machine shaft S1 of the rotating machine 10 without a gear, and a grounding mechanism 14 is provided for each of both ends of the rotating machine shaft S1.

[0048] The other configurations are the same as those in the first embodiment.

[0049] According to the power transmission device 104 of the fourth embodiment, the gear between the rotating machine shaft S1 and the rotating shaft S4 is omitted, thereby enhancing the effect of reducing high frequency components of electromagnetic noise.

[0050] In addition, the same effects as those of the first embodiment are achieved.

[0051] (Embodiment 5) 9, in a power transmission device 105 of the fifth embodiment, both of the rotating machines 10 are configured as in-wheel motors in which the rotating machine S1 is integrally connected to each driving wheel 3. A grounding mechanism 14 is provided at each of both shaft ends S1a of the rotating machine shaft S1. In this case, two grounding mechanisms 14 are used.

[0052] The other configurations are the same as those in the first embodiment.

[0053] The power transmission device 105 of the fifth embodiment can be applied to a vehicle in which the rotating machine 10 is an in-wheel motor.

[0054] In addition, the same effects as those of the first embodiment are achieved.

[0055] (Embodiment 6) 10, the power transmission device 106 of the sixth embodiment differs from the power transmission device 101 of the first embodiment in the position where the grounding mechanism 14 is provided. Also, only the bearings 15 and 21 are made of insulating bearings having electrical insulation properties.

[0056] In the power transmission device 106, the rotating shaft S3 of the reducer 20 is a target rotating shaft, and one of the two shaft ends S3a, S3b of the rotating shaft S3 in the first direction X is a grounding portion for the grounding mechanism 14. The shaft end S3a is a portion that is connected to the power transmission path A and is located within the region from the output side of the rotating machine shaft S1 to the downstream side of the power transmission path A, but is not located on the power transmission path A. This shaft end S3a is grounded to the case 20a via the grounding mechanism 14. Of the two shaft ends S3a, S3b of the rotating shaft S3, this shaft end S3a is the one that is closer in distance from the power transmission path A to the bearing 22 applied to the shaft end.

[0057] Here, when a distance d1 in the first direction X from a reference position P on the power transmission path A at the boundary between the rotating shaft S3 and the gear G2 to the bearing 22 on the left side in the figure is compared with a distance d2 in the first direction X from the reference position P to the bearing 22 on the right side in the figure, the distance d1 is smaller than the distance d2. In this embodiment, of both shaft ends S3a, S3b of the rotating shaft S3, the shaft end S3a supported by the bearing 22 on the left side in the figure that forms the distance d1 is grounded to the case 20a by the grounding mechanism 14.

[0058] The other configurations are the same as those in the first embodiment.

[0059] According to the power transmission device 106 of embodiment 6, by grounding the shaft end S3a of the rotating shaft S3 to the case 20a by the grounding mechanism 14, the effect of the inductance L of the rotating shaft S3 on the shaft voltage can be reduced compared to the case where the other shaft end S3b is grounded to the case 20a by the grounding mechanism 14, and the amount of reduction in high-frequency components of electromagnetic noise can be increased.

[0060] In addition, the same effects as those of the first embodiment are achieved.

[0061] (Embodiment 7) As shown in FIG. 11, the power transmission device 107 of the seventh embodiment differs from the power transmission device 106 of the sixth embodiment in the position where the ground contact mechanism 14 is provided.

[0062] The grounding mechanism 14 of the power transmission device 107 is configured so that, of both shaft ends S3a, S3b of the rotating shaft S3, the shaft end S3b that has a shorter distance from the power transmission path A to the bearing 22 applied to that shaft end is grounded to the case 20a. When a distance d1 in the first direction X from a reference position P on the power transmission path A to the bearing 22 on the right side in the figure is compared with a distance d2 in the first direction X from the reference position P to the bearing 22 on the left side in the figure, the distance d1 is shorter than the distance d2.

[0063] The other configurations are the same as those in the sixth embodiment.

[0064] According to the power transmission device 107 of embodiment 7, by grounding the shaft end S3b of the rotating shaft S3 to the case 20a by the grounding mechanism 14, the effect of the inductance L of the rotating shaft S3 on the shaft voltage can be reduced compared to the case where the other shaft end S3a is grounded to the case 20a by the grounding mechanism 14, and the amount of reduction in high-frequency components of electromagnetic noise can be increased.

[0065] In addition, the same effects as those of the sixth embodiment are achieved.

[0066] (Embodiment 8) As shown in FIG. 12, the power transmission device 108 of the eighth embodiment differs from the power transmission device 106 of the sixth embodiment in the position where the ground contact mechanism 14 is provided.

[0067] The grounding mechanism 14 of the power transmission device 108 is configured to ground the rotating shaft S2 of the reducer 20 as a target rotating shaft to the case 20a at a shaft end S2b that is not located on the power transmission path A. Of both shaft ends S2a, S2b of the rotating shaft S2, the shaft end S2b is the one that is closer in distance from the power transmission path A to the bearing 21 applied to that shaft end.

[0068] Here, when a distance d3 in the first direction X from a reference position Q on the power transmission path A at the boundary between the rotating shaft S2 and the gear G1 to the bearing 21 on the right side in the figure is compared with a distance d4 in the first direction X from the reference position Q to the bearing 21 on the left side in the figure, the distance d3 is smaller than the distance d4. In this embodiment, of both shaft ends S2a, S2b of the rotating shaft S2, the shaft end S2b supported by the bearing 21 on the right side in the figure that forms the distance d3 is grounded to the case 20a by the grounding mechanism 14.

[0069] The other configurations are the same as those in the sixth embodiment.

[0070] According to the power transmission device 108 of embodiment 8, by grounding the shaft end S2b of the rotating shaft S2 to the case 20a by the grounding mechanism 14, the effect of the inductance L of the rotating shaft S2 on the shaft voltage can be reduced compared to the case where the other shaft end S2a is grounded to the case 20a by the grounding mechanism 14, and the amount of reduction in high-frequency components of electromagnetic noise can be increased.

[0071] In addition, the same effects as those of the sixth embodiment are achieved.

[0072] (Embodiment 9) As shown in FIG. 13, the power transmission device 109 of the ninth embodiment differs from the power transmission device 101 of the first embodiment in the structure of the ground contact mechanism 14.

[0073] As shown in the cross-sectional view in the second direction Y in Fig. 14, the grounding mechanism 14 includes a conductive brush 14a and a metal housing 14c that holds the brush 14a. The brush 14a is a ring-shaped brush that is in sliding contact with the entire circumferential direction of the rotating machine shaft S1. The housing 14c is fixed to the case 10a of the rotating machine 10 by a plurality of screw fastening portions 14d provided in the third direction Z.

[0074] The other configurations are the same as those in the first embodiment.

[0075] According to the power transmission device 109 of the ninth embodiment, by using a ring-shaped brush for the grounding mechanism 14, it is possible to perform grounding in a small space and reduce the size of the grounding mechanism 14. In addition, since a conductor such as a pigtail is not required, it is possible to perform grounding with low inductance.

[0076] In addition, the same effects as those of the first embodiment are achieved.

[0077] (Embodiment 10) 15, a power transmission device 110 of the tenth embodiment is similar to the power transmission device 101 of the first embodiment in that it uses a grounding mechanism 14, but differs in that it uses an insulating bearing in addition to the grounding mechanism 14. This power transmission device 110 uses both the grounding mechanism 14 and an insulating bearing.

[0078] The grounding mechanism 14 of the power transmission device 110 is provided so as to ground the shaft end S1b of the rotating shaft S1 to the case 10a. In addition, the bearing 15 applied to the rotating shaft S1 and the bearing 21 applied to the rotating shaft S2 are both configured as insulating bearings having electrical insulation properties.

[0079] As shown in Fig. 16, the bearing 15 includes an outer ring 15a, an inner ring 15b, a plurality of rolling elements 15c held by a cage 15d between the outer ring 15a and the inner ring 15b so as to be capable of rolling, and a seal member 15e that seals the space between the outer ring 15a and the inner ring 15b. The bearing 15 is configured such that at least one of the outer ring 15a, the inner ring 15b, and the plurality of rolling elements 15c is made of an electrically insulating material. Although not specifically shown, the bearing 21 has a similar structure to the bearing 15.

[0080] The other configurations are the same as those in the first embodiment.

[0081] According to the power transmission device 110 of the tenth embodiment, by using insulating bearings for the bearings 15 and 21, it is possible to prevent discharge due to dielectric breakdown even when the rotating shafts S1 and S2 are charged. This makes it possible to suppress leakage of high-frequency components of the shaft voltage (specifically, pulse-like shaft voltage remaining after grounding due to dielectric breakdown of the bearings) to the downstream side of the power transmission path A, thereby reducing the high-frequency components of electromagnetic noise. Another advantage of using insulating bearings is that it is not necessary to consider the problem of brush wear that can occur when using brushes.

[0082] In the power transmission device 110, it is preferable to use ceramics, which have superior durability and insulation rate compared to resin or carbon, as the electrical insulating material of the bearings 15, 21. More preferably, alumina ceramics is used. Alumina ceramics has a high insulation rate and is inexpensive, making it highly versatile.

[0083] Here, as shown in Fig. 17, in a state where dielectric breakdown occurs in the bearings 15, 21 in the power transmission path A' of the comparative example, high-frequency components of the shaft voltage are generated by the discharge of the bearings 15, 21 and propagate to the downstream side of the power transmission path A'. Note that in Fig. 17, the discharge of the bearings 15, 21 is equalized by a switch in the circuit.

[0084] In contrast, according to the present embodiment, by using a grounding mechanism 14 in combination with an insulating bearing as shown in FIG. 18, a path for the shank voltage is formed on the side of the grounding mechanism 14, making it possible to prevent the generation of high-frequency components in the shank voltage and reduce high-frequency components of electromagnetic noise.

[0085] In addition, by providing a grounding mechanism 14 on the rotating machine shaft S1, if a device such as a rotation speed sensor is provided on the rotating machine shaft S1, it is possible to prevent electromagnetic noise from being transmitted to this device.

[0086] Although it is possible to use insulating bearings for all of the bearings 15, 21, 22, and 23, in order to reduce costs, it is sufficient to use insulating bearings only for the bearings 15 and 21, as in the power transmission device 110 of this embodiment.

[0087] In addition, the same effects as those of the first embodiment are achieved.

[0088] (Embodiment 11) As shown in FIG. 19, the power transmission device 111 of embodiment 11 differs from the power transmission device 110 of embodiment 10 in that it does not include a grounding mechanism 14 and that all of the bearings 15, 21, 22, and 23 provided on the rotating shafts S1, S2, S3, and S4 are configured as insulating bearings.

[0089] Here, in the power transmission path A, each gear is electrically connected to another gear with a parasitic capacitance, and the shaft voltages of the rotating shafts S1, S2, S3, and S4 decrease in the order of the rotating machine shaft S1, the rotating shaft S2, the rotating shaft S3, and the rotating shaft S4. At this time, depending on the output of the inverter 4 (see FIG. 1), it is assumed that the high-frequency component of the shaft voltage will drop to a desired level before the high-frequency component of the electromagnetic noise reaches the rotating shaft S4. In the tenth embodiment, taking such a case into consideration, the grounding mechanism 14 is omitted, and all of the bearings 15, 21, 22, and 23 are insulating bearings having a configuration similar to that of the bearing 15 of the first embodiment (FIG. 16).

[0090] The other configurations are the same as those of the tenth embodiment.

[0091] According to the power transmission device 111 of the eleventh embodiment, the high-frequency components of the shaft voltage generated in the rotating machine shaft S1 are divided among the remaining rotating shafts S2, S3, and S4, eliminating the need for the grounding mechanism 14. In this case, there is an advantage in that the omission of the grounding mechanism 14 can provide a cost reduction effect.

[0092] In addition, the same effects as those of the tenth embodiment are achieved.

[0093] (Embodiment 12) As shown in FIG. 20, a power transmission device 112 of the twelfth embodiment differs from the power transmission device 110 of the tenth embodiment in the position where the ground contact mechanism 14 is provided.

[0094] The grounding mechanism 14 of the power transmission device 112 is configured so that the shaft end S3b of the rotating shaft S3 is grounded to the case 20a.

[0095] The other configurations are the same as those of the tenth embodiment.

[0096] According to the power transmission device 112 of the twelfth embodiment, the bearing 15 is an insulating bearing to prevent dielectric breakdown, so that it is not necessary to ground the rotating shaft S1 to the case 10a. Therefore, in this embodiment, the grounding mechanism 14 is applied to the rotating shaft S3 of the reducer 20 instead of the rotating shaft S1, and the rotating shaft S3 is grounded to the case 20a. Since the rotating shaft S3 has a lower rotation speed than the rotating shaft S1, the life of the brush 14a (see FIG. 3) can be extended and the power consumption can be improved compared to the case where the grounding mechanism 14 is applied to the rotating shaft S1. Note that the grounding mechanism 14 can be applied to the rotating shaft S2 of the reducer 20 instead of or in addition to the rotating shaft S3.

[0097] In addition, the same effects as those of the tenth embodiment are achieved.

[0098] (Embodiment 13) As shown in FIG. 21, a power transmission device 113 of the thirteenth embodiment differs from the power transmission device 112 of the twelfth embodiment in the position where the ground contact mechanism 14 is provided.

[0099] The grounding mechanism 14 of the power transmission device 113 is configured so that, of both shaft ends S3a, S3b of the rotating shaft S3, the shaft end S3b that has a shorter distance from the power transmission path A to the bearing 22 applied to that shaft end is grounded to the case 20a. When a distance d1 in the first direction X from a reference position P on the power transmission path A to the bearing 22 on the right side in the figure is compared with a distance d2 in the first direction X from the reference position P to the bearing 22 on the left side in the figure, the distance d1 is shorter than the distance d2.

[0100] The other configurations are the same as those of the twelfth embodiment.

[0101] According to the power transmission device 113 of embodiment 13, by grounding the shaft end S3b of the rotating shaft S3 to the case 20a by the grounding mechanism 14, the effect of the inductance L of the rotating shaft S3 on the shaft voltage can be suppressed compared to the case where the other shaft end S3a is grounded to the case 20a by the grounding mechanism 14, and the amount of reduction in high-frequency components of electromagnetic noise can be increased.

[0102] In addition, the same effects as those of the twelfth embodiment are achieved.

[0103] (Embodiment 14) As shown in FIG. 22, the power transmission device 114 of the fourteenth embodiment differs from the power transmission device 110 of the tenth embodiment in the structure of the ground contact mechanism 14.

[0104] The grounding mechanism 14 of the power transmission device 114 is constituted by a ground wire 14e. A portion electrically connected to the rotating shaft S4 is grounded to the case 20a via the ground wire 14e.

[0105] The other configurations are the same as those of the tenth embodiment.

[0106] According to the power transmission device 114 of the fourteenth embodiment, there is no need to consider the problem of brush wear that may occur when using brushes, and therefore the cost of the grounding mechanism 14 can be reduced.

[0107] In addition, the same effects as those of the tenth embodiment are achieved.

[0108] (Embodiment 15) As shown in FIG. 23, a power transmission device 115 of the fifteenth embodiment has a ground contact mechanism 14A, and the structure of this ground contact mechanism 14A differs from that of the ground contact mechanism 14 of the first embodiment (see FIG. 3).

[0109] The grounding mechanism 14A has a conductive brush 14a and a spring 14b as an elastic body that presses the brush 14a against the circumferential surface of the rotor shaft S1, which is the target rotating shaft. As shown in Fig. 24, the spring 14b is a conductive barb spring interposed between the brush 14a and the ground 10b. The spring 14b is typically formed by processing a metal plate with a rectangular cross section so as to be wound into a cone shape.

[0110] The spring 14b electrically connects the brush 14a and the ground 10b to form a ground path, and also serves to elastically bias the brush 14a and the ground 10b in a direction separating them from each other, thereby pressing the brush 14a against the circumferential surface of the rotor shaft S1 so as to come into sliding contact with the brush 14a.

[0111] The spring 14b is configured so that its cross-sectional shape in the second direction Y, which is the spring expansion / contraction direction, is rectangular and non-circular. Therefore, the spring 14b differs from a typical coil spring, which has a circular cross-sectional shape (see FIG. 23). The ground 10b is configured by a metal terminal electrically connected to the case 10a.

[0112] The other configurations are the same as those in the first embodiment.

[0113] According to the power transmission device 115 of the fifteenth embodiment, the cross-sectional area of ​​the spring 14b is larger than that of a general ground wiring (lead wire), so that the contact area with the brush 14a and the ground 10b can be increased and the inductance can be reduced. In this case, the ground impedance for the high-frequency components of the electromagnetic noise is reduced, so that the ground effect is increased, which is effective in reducing the high-frequency components of the shaft voltage.

[0114] Furthermore, by using a barb spring for spring 14b, the inductance for the same linear shape (cross-sectional area) can be made smaller than that of a coil spring with a circular cross-sectional shape, which increases the effect of reducing high-frequency components of the axial voltage and increases the grounding effect.

[0115] In addition, the same effects as those of the first embodiment are achieved.

[0116] In the grounding mechanism 14A, instead of using a barb spring as the spring 14b, a square spring having a non-circular cross-sectional shape similar to the barb spring may be used, if necessary.

[0117] (Embodiment 16) As shown in FIG. 25, the power transmission device 116 of the sixteenth embodiment has a ground contact mechanism 14B, and the structure of this ground contact mechanism 14B is different from that of the ground contact mechanism 14A of the fifteenth embodiment.

[0118] The grounding mechanism 14B has a grounding wire 14f in addition to the spring 14b. The grounding wire 14f electrically connects the brush 14a and the ground 10b, thereby forming a grounding path separate from the spring 14b.

[0119] The other configurations are the same as those of the fifteenth embodiment.

[0120] According to the power transmission device 116 of the sixteenth embodiment, two ground paths are formed in parallel in the ground mechanism 14B, so that the inductance can be made smaller than in the fifteenth embodiment.

[0121] In addition, it has the same effects as the fifteenth embodiment.

[0122] (Embodiment 17) As shown in FIG. 26, a power transmission device 117 of the seventeenth embodiment has a ground contact mechanism 14C, and the structure of this ground contact mechanism 14C differs from that of the ground contact mechanism 14A of the fifteenth embodiment.

[0123] The grounding mechanism 14C has a spring 14g as a second elastic body in addition to the spring 14b as a first elastic body. In the grounding mechanism 14C, the spring 14b is a coil spring for sliding contact, and the spring 14g is a leaf spring for grounding.

[0124] The spring 14b serves to elastically bias the brush 14a so that the brush 14a slides against the circumferential surface of the rotor shaft S1. The spring 14b has a circular cross-sectional shape. In contrast, the spring 14g is conductive and electrically connects the brush 14a and the ground 10b to form a ground path. At this time, the spring 14g serves to maintain the grounded state by elastically biasing the brush 14a and the ground 10b in a direction separating them from each other. The spring 14g has a non-circular cross-sectional shape.

[0125] The other configurations are the same as those of the fifteenth embodiment.

[0126] According to the power transmission device 117 of the seventeenth embodiment, in the ground contact mechanism 14C, a coil spring as the sliding contact spring 14b and a leaf spring as the ground contact spring 14g can be used in combination.

[0127] In addition, it has the same effects as the fifteenth embodiment.

[0128] (Embodiment 18) As shown in FIG. 27, a power transmission device 118 of the eighteenth embodiment has a ground contact mechanism 14D, and the structure of this ground contact mechanism 14D is different from that of the ground contact mechanism 14C of the seventeenth embodiment.

[0129] The grounding mechanism 14D has a brush 14a and two springs 14b and 14g. The spring 14b is a coil spring for sliding contact, and the spring 14g is a barbed spring for grounding (see FIG. 24). The spring 14g has a non-circular cross-sectional shape. The spring 14g is conductive, and one end in the first direction X contacts the ground 10b, while the other end in the first direction X is electrically connected to the brush 14a with a conductive sliding terminal 14h sandwiched therebetween.

[0130] The other configurations are the same as those of the seventeenth embodiment.

[0131] According to the power transmission device 118 of the eighteenth embodiment, in the ground contact mechanism 14D, a coil spring as the sliding contact spring 14b and a bar spring as the ground contact spring 14g can be used in combination.

[0132] In addition, it has the same effects as the seventeenth embodiment.

[0133] In each of the seventeenth and eighteenth embodiments, a bar spring or a square spring may be used instead of the coil spring for the spring 14b. That is, springs having a non-circular cross section may be used for both the sliding contact spring 14b and the ground contact spring 14g.

[0134] (Embodiment 19) As shown in FIG. 28, a power transmission device 119 of the nineteenth embodiment has a ground contact mechanism 14E, and the structure of this ground contact mechanism 14E is different from that of the ground contact mechanism 14A of the fifteenth embodiment.

[0135] 29, the grounding mechanism 14E has a brush 14a, two springs 14b and 14g, and a holding portion 14i. The spring 14b as a first elastic body is a coil spring for sliding contact, and the spring 14g as a second elastic body is a coil spring for grounding.

[0136] The brush 14a is in direct contact with both the circumferential surface of the rotor shaft S1 and the ground 10b. That is, the brush 14a has a contact point Ca with the rotor shaft S1 and a contact point Cb with the ground 10b. In this case, the rotor shaft S1 is grounded to the ground 10b only via the brush 14a. The contact point Ca is formed on an end face of the brush 14a at one end on the rotor shaft S1 side. The contact point Cb is formed on a side face of the brush 14a between the one end on the rotor shaft S1 side and the other end on the accommodation space 14j side of the housing 10c.

[0137] The ground 10b is made of a metal conductor electrically connected to the case 10a and is held by a holding portion 14i. The spring 14g elastically biases the brush 14a in a direction in which the contact pressure between the brush 14a and the ground 10b increases. Note that the spring 14g may be configured to elastically bias the ground 10b in a direction in which the contact pressure between the brush 14a and the ground 10b increases, instead of or in addition to the brush 14a.

[0138] The other configurations are the same as those of the fifteenth embodiment.

[0139] According to the power transmission device 119 of the nineteenth embodiment, by grounding the rotor shaft S1 to the ground 10b only via the brush 14a, the grounding inductance between the rotor shaft S1 and the ground 10b is reduced compared to the case where a conductor such as a pigtail is used for grounding, and it is possible to reduce the high frequency components of the shaft voltage.

[0140] In addition, it has the same effects as the fifteenth embodiment.

[0141] (Embodiment 20) As shown in FIG. 30, a power transmission device 120 of the twentieth embodiment has a ground contact mechanism 14F, and the structure of this ground contact mechanism 14F is different from that of the ground contact mechanism 14E of the nineteenth embodiment.

[0142] In the grounding mechanism 14F, the spring 14g is a leaf spring portion for grounding that is configured as part of the housing 14c, and this leaf spring portion elastically urges the brush 14a to press it against the gland 10b. Here, the contact of the spring 14g with the brush 14a does not involve sliding, unlike the contact between the rotor shaft S1 and the brush 14a, and the amount of pressing is small, so that the leaf spring portion can be used instead of a coil spring.

[0143] The other configurations are the same as those of the 19th embodiment.

[0144] According to the power transmission device 120 of the twentieth embodiment, the spring 14g is formed by utilizing a part of the housing 14c, thereby making it possible to reduce the number of parts.

[0145] In addition, it has the same effects as the 19th embodiment.

[0146] In addition, in the above-mentioned grounding mechanism 14F, it is preferable that the housing 14c is configured so that the dimension of the accommodating space 14j in the third direction Z exceeds the opening width in the third direction Z of the opening 14k facing the peripheral surface of the rotor shaft S1 (see Figure 30).

[0147] 31, when the rotor shaft S1 rotates in the first rotation direction D1, the end of the brush 14a on the rotor shaft S1 side receives a load moving toward the left side in the figure. At this time, the movement of the end of the brush 14a on the rotor shaft S1 side is restricted by the opening edge of the housing 14c, while the end of the brush 14a on the accommodation space 14j side is prevented from interfering with the right wall surface of the accommodation space 14j.

[0148] As shown in Fig. 32, when the rotor shaft S1 rotates in the second rotation direction D2, the brush 14a receives a load such that the end of the brush 14a on the rotor shaft S1 side moves toward the right side in the figure. At this time, the movement of the end of the brush 14a on the rotor shaft S1 side is restricted by the contact point Cc formed with the retaining portion 14i, while the end of the brush 14a on the accommodation space 14j side is prevented from interfering with the left wall surface of the accommodation space 14j. If the retaining portion 14i is conductive, an electrical connection is formed not only with the ground 10b but also with the retaining portion 14i.

[0149] Therefore, regardless of the direction of rotation of the rotor shaft S1, the brush 14a can maintain an electrical connection with the ground 10b at the contact point Cb formed between both ends of the brush 14a, and the rotor shaft S1 can be stably grounded to the ground 10b via the brush 14a.

[0150] (Embodiment 21) As shown in FIG. 33, a power transmission device 121 of the twenty-first embodiment has a ground contact mechanism 14G, and the structure of this ground contact mechanism 14G is different from that of the ground contact mechanism 14E of the nineteenth embodiment.

[0151] In the grounding mechanism 14G, the brush 14a has a cross-sectional shape that is substantially L-shaped when viewed in the axial direction of the rotor shaft S1. One end of the brush 14a is elastically biased by a spring 14b in a direction away from the rotor shaft S1, so that the end face of the other end of the brush 14a contacts the peripheral surface of the rotor shaft S1 at a contact point Ca. An intermediate portion between both ends of the brush 14a contacts the ground 10b at a contact point Cb.

[0152] The brush 14a is pressed against the rotor shaft S1 and the gland 10b by utilizing the so-called "lever principle." In this case, one end of the brush 14a serves as a force point, either the other end or the middle part of the brush 14a serves as a fulcrum, and either the other end or the middle part of the brush 14a serves as a point of action. The spring 14b serves both as a spring for sliding contact and a spring for grounding. The spring 14b elastically biases the brush 14a so that the contact pressure of the brush 14a against both the rotor shaft S1 and the gland 10b increases. This allows the rotor shaft S1 to be stably grounded to the gland 10b via the brush 14a.

[0153] The other configurations are the same as those of the 19th embodiment.

[0154] According to the power transmission device 121 of the twenty-first embodiment, the number of springs can be reduced compared to the nineteenth embodiment.

[0155] In addition, it has the same effects as the 19th embodiment.

[0156] (Embodiment 22) As shown in FIG. 34, the power transmission device 122 of the twenty-second embodiment differs from the power transmission device 101 of the first embodiment in that the power transmission device 122 does not include the ground contact mechanism 14.

[0157] The power transmission device 122 includes a first conductor 17, a second conductor 18, a spacer Sp, and a capacitance generating portion 19.

[0158] The first conductor 17 is provided on the rotating machine axis S1 so as to rotate integrally with the rotor 11 (see FIG. 2) of the rotating machine 10. The first conductor 17 is a flat plate with a constant thickness in the first direction X, and has a disk shape that is circular when viewed in the first direction X (see FIG. 35). This allows the first conductor 17 to be made compact.

[0159] The second conductor 18 is fixed directly or indirectly to the stator 12 of the rotating machine 10, and is configured to be disposed opposite the first conductor 17 in the first direction X, which is the axial direction. Like the first conductor 17, the second conductor 18 is a flat plate with a constant thickness in the first direction X, and has a disk shape that is circular when viewed in the first direction X. This allows the second conductor 18 to be made compact.

[0160] The first conductor 17 has a circular opposing surface 17a with the first direction X as the normal direction relative to the second conductor 18. The second conductor 18 has a circular opposing surface 18a with the first direction X as the normal direction relative to the first conductor 17. The two opposing surfaces 17a, 18a are planes perpendicular to the first direction X and are arranged parallel to each other.

[0161] The spacer Sp is interposed between the first conductor 17 and the bearing 15 to determine the distance between the two opposing surfaces 17a, 18a. The spacer Sp simplifies the process of setting the desired distance between the two opposing surfaces 17a, 18a. The number of spacers Sp is not particularly limited, and one or more spacers Sp can be provided as necessary.

[0162] The capacitance forming portion 19 is formed between the opposing surface 17a of the first conductor 17 and the opposing surface 18a of the second conductor 18. According to this capacitance forming portion 19, a dielectric 19a is interposed between the two opposing surfaces 17a, 18a, thereby forming a capacitance. At this time, the smaller the distance between the two opposing surfaces 17a, 18a, the larger the capacitance becomes. Although the type of the dielectric 19a is not particularly limited, grease can be used as the dielectric 19a in order to increase the capacitance.

[0163] The other configurations are the same as those in the first embodiment.

[0164] According to the power transmission device 122 of the twenty-second embodiment, when the vibration in the axial direction (first direction X) of the rotating machine shaft S1 is small, by forming a capacitance between the two opposing surfaces 17a, 18a perpendicular to the first direction X, it is possible to suppress the high-frequency component of the shaft voltage generated in the rotating machine shaft S1 from propagating to the downstream side of the power transmission path A even when a grounding mechanism is not used. This makes it possible to prevent the generation of high-frequency components of electromagnetic noise. Of course, a grounding mechanism may be added to this power transmission device 122.

[0165] In addition, the same effects as those of the first embodiment are achieved.

[0166] (Embodiment 23) As shown in FIG. 36, a power transmission device 123 of the twenty-third embodiment differs from the power transmission device 122 of the twenty-second embodiment in the structures of a first conductor 17 and a second conductor 18.

[0167] In the power transmission device 123, the first conductor 17 has a plurality of (two in FIG. 36) flat plate portions 17b arranged in parallel with a gap in the first direction X, and the second conductor 18 has a plurality of (three in FIG. 36) flat plate portions 18b arranged in parallel with a gap in the first direction X.

[0168] One flat plate portion 18b of second conductor 18 is configured as a portion shared with case 10a. This allows the number of parts to be reduced. Note that, if necessary, an element other than second conductor 18 may have a portion shared with case 10a.

[0169] The flat plate portions 17b of the first conductor 17 and the flat plate portions 18b of the second conductor 18 are alternately arranged in the first direction X. At this time, the opposing surface of the flat plate portion 17b opposing the flat plate portion 18b and the case 10a becomes the opposing surface 17a of the first conductor 17, and the opposing surface of the flat plate portion 18b opposing the flat plate portion 17b becomes the opposing surface 18a of the second conductor 18. Therefore, in this embodiment, four opposing surfaces 17a and three opposing surfaces 18a are formed, and capacitance forming portions 19 are formed in multiple locations (four locations in FIG. 36).

[0170] The first conductor 17 has an inner peripheral portion 17c. This inner peripheral portion 17c is a joint portion with the peripheral surface of the rotor shaft S1, and also constitutes the spacer Sp of the twenty-second embodiment. In this way, by making the inner peripheral portion 17c of the first conductor 17 a common portion with the spacer Sp, the number of parts can be reduced compared to the case where the spacer Sp is a dedicated part. Note that the spacer Sp may be constituted by using a part of the second conductor 18, if necessary.

[0171] 37, the first conductor 17 is composed of two divided parts that can be divided into halves at a position corresponding to the rotor axis S. This simplifies the assembly work of the first conductor 17. Note that, if necessary, the first conductor 17 can be composed of three or more divided parts, and the second conductor 18 can be composed of multiple divided parts.

[0172] The other configurations are the same as those of the twenty-second embodiment.

[0173] According to the power transmission device 123 of the twenty-third embodiment, by providing a plurality of opposing surfaces 17a, 18a, the number of locations where the capacitance generating portion 19 is formed can be increased, and the capacitance can be increased.

[0174] In addition, the same effects as those of the twenty-second embodiment are achieved.

[0175] (Embodiment 24) As shown in FIG. 38, a power transmission device 124 of the twenty-fourth embodiment differs from the power transmission device 122 of the twenty-second embodiment in the structures of the first conductors 17 and the second conductors 18.

[0176] In the power transmission device 124, the first conductor 17 is formed by the rotor 11 itself. Therefore, the first conductor 17 is formed by a portion shared with the rotor 11. The second conductors 18 are provided on both sides of the rotor 11 in the first direction X. The two second conductors 18 are formed by a portion shared with the rotation speed sensor R provided on the rotating machine axis S1. Both sides of the rotor 11 form opposing surfaces 17a that face the opposing surfaces 18a of each of the second conductors 18.

[0177] The other configurations are the same as those of the twenty-second embodiment.

[0178] According to the power transmission device 124 of the twenty-fourth embodiment, the first conductor 17 is configured by a portion shared with the rotor 11, and the second conductor 18 is configured by a portion shared with the rotation speed sensor R, thereby making it possible to reduce the number of parts.

[0179] In addition, the same effects as those of the twenty-second embodiment are achieved.

[0180] (Embodiment 25) As shown in FIG. 39, a power transmission device 125 of the twenty-fifth embodiment differs from the power transmission device 122 of the twenty-second embodiment in the structures of the first conductors 17 and the second conductors 18.

[0181] In the power transmission device 125, the first conductor 17 is formed of a first gear G1 (see FIG. 2) provided around the axial circumference of the rotating shaft S2. Therefore, the first conductor 17 is formed of a common portion with the first gear G1. The second conductors 18 are provided on both sides of the first gear G1 in the first direction X. Both sides of the first gear G1 form opposing surfaces 17a that face the opposing surfaces 18a of the second conductors 18.

[0182] The other configurations are the same as those of the twenty-second embodiment.

[0183] According to the power transmission device 125 of the twenty-fifth embodiment, the first conductor 17 is formed by a portion shared with the first gear G1, so that the number of parts can be reduced.

[0184] In addition, the same effects as those of the twenty-second embodiment are achieved.

[0185] (Embodiment 26) As shown in FIG. 41, a power transmission device 126 of the twenty-sixth embodiment has a ground contact mechanism 14H, and the structure of this ground contact mechanism 14H is different from that of the ground contact mechanism 14 of the first embodiment (see FIG. 3).

[0186] The grounding mechanism 14H is provided between the shaft end S1b of the rotating machine shaft S1 and the ground 10b. The grounding mechanism 14H has a conductive brush 14a and a conductive elastic spring 14b interposed between the brush 14a and the shaft end S1b.

[0187] 41 and 42, the spring 14b is a leaf spring that is conductive, has a noncircular cross-sectional shape, and is flexible in the first direction X. The spring 14b is fitted into a hollow portion S1c that is provided in a concave shape in the end surface of the shaft end portion S1b of the rotor shaft S1. The hollow portion S1c is concentric with the rotor shaft S1 and forms a space with a smaller diameter than the rotor shaft S1. When the spring 14b is fitted into the hollow portion S1c, it receives a load from the rotor shaft S1 in the first direction X, and is therefore securely held by the rotor shaft S1.

[0188] 41, the ground 10b is configured as a cover provided on the case 10a so as to cover the shaft end S1b. The ground 10b is conductive and is electrically connected to the spring 14b via the brush 14a.

[0189] The brush 14a is fixed to the spring 14b by crimping, thereby forming an integrated module with the spring 14b. The brush 14a has a contact point Cd that contacts the gland 10b on the central axis M of the rotor shaft S1. The brush 14a is elastically biased by the spring 14b in a direction that increases the contact pressure at the contact point Cd.

[0190] The other configurations are the same as those in the first embodiment.

[0191] According to the power transmission device 126 of the twenty-sixth embodiment, the spring 14b is fitted into the hollow portion S1c of the rotor shaft S1, so that the ground contact mechanism 14H requires less space, thereby making it possible to reduce the size of the device.

[0192] By using a leaf spring with a non-circular cross section as the spring 14b and increasing the contact area with the brush 14a, it is possible to reduce the inductance, thereby reducing the high frequency components of the axial voltage. In addition, such a leaf spring is effective in replacing a general coil spring in a structure in which the amount of wear of the brush 14a is relatively small and the pressing stroke in the first direction X is relatively small.

[0193] In addition, the same effects as those of the first embodiment are achieved.

[0194] (Embodiment 27) As shown in FIG. 43, a power transmission device 127 of the twenty-seventh embodiment has a ground contact mechanism 14I, and the structure of this ground contact mechanism 14I is different from that of the ground contact mechanism 14H of the twenty-sixth embodiment.

[0195] In the grounding mechanism 14I, the brush 14a is releasably fastened to the gland 10b by a bolt member BT. The brush 14a has a contact point Ce that contacts the spring 14b on the central axis M of the rotating machine shaft S1. The brush 14a is elastically biased by the spring 14b in a direction that increases the contact pressure at the contact point Ce.

[0196] The other configurations are the same as those of the twenty-sixth embodiment.

[0197] According to the power transmission device 127 of the twenty-seventh embodiment, the brush 14a of the grounding mechanism 14H is fastened to the gland 10b by the bolt member BT, so that the brush 14a can be removed from the gland 10b and replaced according to its wear, thereby improving the maintainability of the grounding mechanism 14H.

[0198] In addition, it has the same effects as the twenty-sixth embodiment.

[0199] The present invention is not limited to the exemplary embodiments described above, and various applications and modifications are possible without departing from the scope of the present invention. For example, modified examples can be implemented by appropriately combining the characteristic parts of the above-described embodiments. [Explanation of symbols]

[0200] 1...vehicle, 2...vehicle body, 3...driving wheel, 4...inverter, 10...rotating machine, 10b...ground, 11...rotor, 12...stator, 14, 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14I...grounding mechanism, 14a...brush, 14b...spring (elastic body, first elastic body), 14e...earth wire, 14g...spring (second elastic body), 15, 21, 22, 23...bearing, 15a...outer ring, 15b...inner ring, 15c...rolling body, 16, 24, 25...power transmission section, 17...first conductor body, 17a...opposing surface, 18...second conductor, 18a...opposing surface, 19...capacitance forming portion, 20...reduction gear, 101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127...vehicle power transmission device, A...power transmission path, S1,S2,S3,S4...rotating shaft, S1...rotating machine shaft, S4...drive shaft, G5...planetary gear

Claims

1. A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), A plurality of rotating shafts (S1, S2, S3, S4) including a rotating machine shaft (S1) of the rotating machine; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, respectively; A grounding mechanism (14, 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14I); Equipped with A vehicle power transmission device (101, 102, 103, 104, 105, 109, 115, 116, 117, 118, 119, 120, 121, 126, 127), wherein the rotating machine shaft has an output side shaft end (S1a) located on the power transmission path that is grounded to the vehicle body (2) via the grounding mechanism.

2. The plurality of rotating shafts includes a drive shaft (S4) that drives the drive wheels, 2. The vehicle power transmission device according to claim 1, wherein the plurality of power transmission parts mechanically transmit the driving force of the rotary machine to the drive shaft via a plurality of gears.

3. 3. The vehicle power transmission device according to claim 2, wherein the plurality of gears includes a planetary gear (G5).

4. 4. The vehicle power transmission device according to claim 1, wherein the rotating machine is an in-wheel motor configured such that the rotating machine shaft is integrally connected to the drive wheel.

5. The plurality of rotating shafts includes a drive shaft (S4) that drives the drive wheels, 2. The power transmission device for a vehicle according to claim 1, wherein the drive shaft is connected to each of both shaft ends of the rotating machine shaft.

6. The vehicle power transmission device according to any one of claims 1 to 5, wherein the grounding mechanism includes a conductive brush (14a) and an elastic body (14b) that applies pressure to the brush so as to press it against the peripheral surface of the shaft end of the rotating machine shaft.

7. 7. The vehicle power transmission device according to claim 6, wherein the grounding mechanism has a conductive second elastic body (14g) interposed between the brush and the ground (10b) when the elastic body is a first elastic body (14b), and the second elastic body electrically connects the brush and the ground and elastically biases the brush and the ground in a direction separating them from each other.

8. 8. The vehicle power transmission device according to claim 7, wherein at least one of the first spring which is the first elastic body and the second spring which is the second elastic body is configured so that its cross-sectional shape in the spring extension / contraction direction is non-circular.

9. 7. The vehicle power transmission device according to claim 6, wherein the grounding mechanism has a second elastic body (14g) that elastically biases at least one of the brush and the ground in a direction that increases the contact pressure between the brush and the ground when the brush is in direct contact with the ground (10b) and the elastic body is a first elastic body (14b).

10. the grounding mechanism has a conductive brush (14a) and a conductive elastic body (14b) interposed between the brush and the shaft end of the rotating machine shaft, the elastic body and a ground (10b) being electrically connected via the brush; 6. The vehicle power transmission device according to claim 1, wherein the brush has a contact point that contacts the ground or the elastic body on the central axis (M) of the rotating machine shaft, and is elastically biased by the elastic body in a direction that increases contact pressure at the contact point.

11. A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), A plurality of rotation axes (S1, S2, S3, S4), a plurality of bearings (15, 21, 22, 23) for rotatably supporting the plurality of rotating shafts; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, a grounding mechanism (14) for grounding a target rotating shaft, which is at least one of the plurality of rotating shafts, to a body (2) of the vehicle; Equipped with a reducer (20) constituting the power transmission path is provided, and a reducer shaft (S2, S3) of the reducer is the symmetric rotation shaft; The plurality of bearings include an insulating bearing having an outer ring (15a), an inner ring (15b), and a plurality of rolling elements (15c) held for rolling between the outer ring and the inner ring, and at least one of the outer ring, the inner ring, and the plurality of rolling elements is made of an electrically insulating material.

12. 12. The vehicle power transmission device according to claim 11, wherein the target rotating shaft is a portion not located on the power transmission path, and one of the two shaft ends that is a shorter distance from the power transmission path to the bearing provided at that shaft end is grounded to the vehicle body via the grounding mechanism.

13. 13. The power transmission device for a vehicle according to claim 11, wherein the grounding mechanism is constituted by a ground wire (14e) electrically connected to the target rotating shaft.

14. 14. The power transmission device for a vehicle according to claim 11, wherein all of the plurality of bearings are the insulating bearings.

15. a first conductor (17) that rotates integrally with the rotor (11) of the rotating machine; a second conductor (18) fixed directly or indirectly to the stator (12) of the rotating machine and disposed opposite to the first conductor in the axial direction of the rotating machine shaft (S1); a capacitance forming portion (19) formed between the opposing surface (17a) of the first conductor and the opposing surface (18a) of the second conductor; The vehicle power transmission device according to any one of claims 11 to 14, comprising:

16. A vehicle power transmission device that transmits a driving force of a rotating machine (10) controlled by an inverter (4) to driving wheels (3) of a vehicle (1) through a power transmission path (A), A plurality of rotating shafts (S1, S2, S3, S4) including a rotating machine shaft (S1) of the rotating machine; a plurality of power transmission units (16, 24, 25) for transmitting power between the plurality of rotating shafts, A grounding mechanism (14, 14C, 14D, 14E, 14F, 14H, 14I); Equipped with a target rotating shaft which is at least one of the plurality of rotating shafts has a grounding portion which is connected to the power transmission path and is located within a region from an output side of the rotating shaft to a downstream side of the power transmission path and is grounded to the body (2) of the vehicle via the grounding mechanism, The grounding mechanism includes a conductive brush (14a), a first elastic body (14b) that applies pressure to the brush so as to press it against the peripheral surface of the target rotating shaft, and a conductive second elastic body (14g) that is interposed between the brush and a ground (10b), and the second elastic body electrically connects the brush and the ground and elastically biases the brush and the ground in a direction separating them from each other, in a vehicle power transmission device (101, 102, 103, 104, 105, 106, 107, 108, 117, 118, 119, 120, 126, 127).

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