JP2007078174A - Power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device using a compact mechanism with a less number of components for giving speed reducing rotation to a wheel while transmitting thereto the rotating power of an electric motor at a great reduction ratio. <P>SOLUTION: An input wheel 7 is integrally fitted to the inside of a rotor 6 of the electric motor 4. External gears 10a, 10b are rotatably provided outside eccentric shaft portions 8a, 8b provided at the ends of the input wheel 7. The external gears 10a, 10b are meshed with fixed internal gears 11a, 11b provided outside and having a different number of teeth, and the external gears 10a, 10b are revolved by the rotation of the input wheel 7 while being meshed one by one with the internal teeth of the internal gears 11a, 11b and the external gears 10a, 10b are rotated by a difference in the number of teeth of the internal gears 11a, 11b per one rotation of the input wheel 7. The rotating motion of the external gears 10a, 10b is transmitted via a torque transmission mechanism 21 to flanges 18a, 18b of a hub shaft 16 inserted into the input wheel 7 to give speed reducing rotation to the hub shaft 16 and an output wheel 25 fixed to the hub shaft 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power transmission device that transmits rotational power between an electric motor and wheels.

  As power transmission devices that decelerate the rotation of the rotor of the electric motor and transmit it to the wheels of the vehicle, those described in Patent Document 1 and Patent Document 2 are conventionally known. An in-wheel motor drive device described in Patent Document 1 includes an electric motor that generates a driving force, a wheel shaft to which a wheel of a wheel is connected, and a speed reducer that decelerates the rotation of the electric motor and transmits it to the wheel shaft. As the speed reducer, a parallel shaft type gear speed reducer in which a plurality of gears having different numbers of teeth is combined is employed.

  On the other hand, in the electric vehicle speed reduction device described in Patent Document 2, a planetary gear speed reduction mechanism is provided in two stages between the rotor of the electric motor and the wheel hub. Is distributed to the left and right unsprung wheels via the drive shaft.

JP 2005-7914 A JP-A-5-332401

  By the way, in the in-wheel motor drive device described in Patent Document 1, since a large-scale power transmission mechanism such as a propeller shaft and a differential is not necessary, attention has been paid from the viewpoint of reducing the weight and downsizing of the vehicle. The parallel shaft type gear reducer has a reduction ratio of about 1/2 to 1/3, and is not sufficient as a reducer mounted on an in-wheel motor drive device, and the weight of the reducer is heavy. However, the increase in unsprung weight has the disadvantage that the ride comfort becomes worse, and it has not yet been put into practical use.

  On the other hand, although the planetary gear type reduction mechanism of the reduction gear for electric vehicles described in Patent Document 2 can obtain a large reduction ratio as compared with the parallel shaft type gear reduction device, the reduction gear mounted on the in-wheel motor drive device. The machine is still inadequate. In order to obtain a sufficient reduction ratio, it is necessary to make a planetary gear type reduction mechanism composed of a sun gear, ring gear, pinion gear and pinion gear carrier in a multi-stage configuration, which increases the number of parts and makes it difficult to make it compact. The problem of increasing the weight and size of the reducer occurs.

  An object of the present invention is to provide a power transmission device having a compact configuration with a small number of parts that can transmit rotation of an electric motor to a wheel with a large reduction ratio.

  In order to solve the above-described problems, in the present invention, an electric motor in which a rotor is rotatably provided in a casing fixed to a vehicle body side (a vehicle body including a suspension device) and a stator fixed to the inner periphery of the casing. A motor, an input wheel that is incorporated in the rotor of the electric motor and rotates integrally with the rotor, and an eccentric shaft portion is formed at the shaft end, and is fixed to the casing and arranged coaxially with the input wheel The internal gear is rotatably supported by the eccentric shaft portion of the input wheel and meshes with the internal gear. The number of teeth is smaller than that of the internal gear that rotates while the rotor rotates and revolves by meshing with the internal teeth of the internal gear. An external gear, a hub shaft that is inserted into the input wheel and rotatably supported, and has a flange that faces the external gear in the axial direction, and is provided between the external gear and the flange of the hub shaft. External teeth A torque transmission mechanism that absorbs the revolving motion of the external gear and transmits the rotation of the external gear to the flange, an output wheel that is fitted to the shaft end of the hub shaft and is prevented from rotating, and has a wheel mounting flange on the outer periphery, The vehicle body side mounting flange is provided on the outer periphery, and a configuration comprising an outer member that rotatably supports the output wheel via double row rolling elements is adopted.

  In the power transmission device configured as described above, when the rotor is rotated by energizing the stator, the input wheel rotates together with the rotor, and the eccentric shaft portion provided at the shaft end portion of the input wheel rotates eccentrically. Due to the eccentric rotation of the eccentric shaft portion, the external teeth of the external gear supported by the eccentric shaft portion revolve around the rotational axis of the input wheel while meshing with the internal teeth of the internal gear one by one.

  At this time, since the number of external teeth of the external gear is smaller than the number of internal teeth of the internal gear, the external gear reverses the rotation direction of the input ring by the difference in the number of teeth between the internal gear and the external gear per rotation of the input ring. Rotating in the direction, the rotation motion is transmitted to the flange via the torque transmission mechanism, and the hub shaft and the output wheel fixed to the hub shaft rotate at a reduced speed.

  Here, the external teeth of the external gear and the internal teeth of the internal gear may be involute teeth, the external teeth of the external gear may be trochoidal curve teeth, and the internal teeth of the internal gear may be external pins. As in the latter case, when the external teeth of the external gear are trochoidal curved teeth and the internal teeth of the internal gear are external pins, the meshing rate can be increased and the power transmission device is excellent in durability with little damage to the teeth. Can be obtained.

  In the power transmission device according to the present invention, as a torque transmission mechanism, a plurality of pins are provided on one of the opposed surfaces of the external gear and the flange at equal intervals on a concentric circle, and each pin is formed from a pin diameter formed on the other of the opposed surfaces. It is possible to employ a configuration in which each pin is inserted into a large circular hole and each pin is brought into contact with a part of the inner periphery of each circular hole.

  In the power transmission device as described above, there are two eccentric shaft portions formed on the input wheel, the external gears are rotatably supported by the eccentric shaft portions, and each of the internal gears meshed with the respective external gears is formed in the casing. The hub shaft that is fixed and inserted into the input wheel is provided with a flange facing each of the eccentric shaft portions, and the torque transmission mechanism is provided between the opposing surfaces of the flange and the external gear. The rotational power can be transmitted from the two paths to the hub shaft and the output wheel, the load of the rotational power transmitted from one path can be reduced, and the rotational power can be transmitted more stably.

  Here, if the two eccentric shaft portions are provided with a 180 ° phase shift in the circumferential direction, vibrations generated by the eccentric rotation of the eccentric shaft portions can be canceled out, so that a power transmission device that generates less vibration is obtained. be able to.

  In the power transmission device according to the present invention, when a roller is rotatably fitted to each of a plurality of pins forming the torque transmission mechanism and each roller is brought into contact with a part of the inner periphery of the circular hole, the pin and the circular hole are Contact resistance can be reduced, and torque loss can be reduced.

  Further, the support rigidity of the external gear can be increased by relatively rotatably supporting the input wheel and the hub shaft by means of a rolling bearing incorporated inside the eccentric shaft portion of the input wheel.

  As described above, in the power transmission device according to the present invention, the rotation of the rotor causes the external gear meshing with the fixed internal gear to rotate by the difference in the number of teeth between the internal gear and the external gear, and the rotational motion is a torque transmission mechanism. Thus, the power of the electric motor composed of the stator and the rotor can be transmitted to the output wheel with a large reduction ratio.

  In addition, since the speed reduction mechanism has a small number of parts including an internal gear and an external gear, a small and compact power transmission device can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a casing 2 is provided on the inboard side of a knuckle 1 as a vehicle body. The casing 2 is fixed to a flange 34 of an outer member 32, which will be described later, by tightening bolts 3, and an electric motor 4 is incorporated therein.

  The electric motor 4 includes a stator 5 attached to an inner diameter surface of the casing 2 and a rotor 6 incorporated inside the stator 5, and the rotor 6 is rotated by supplying electric power to the stator 5. Yes.

  An input wheel 7 is fitted inside the rotor 6 and integrated with the rotor 6. The input wheel 7 has an outer cylinder portion 7a fitted to the inner diameter surface of the rotor 6 and an inner cylinder portion 7b, and eccentric shaft portions 8a and 8b are formed at both ends of the inner cylinder portion 7b. The two eccentric shaft portions 8a and 8b are 180 ° out of phase in the circumferential direction, and external gears 10a and 10b are rotatably supported via needle roller bearings 9 outside the eccentric shaft portions 8a and 8b. .

  Internal gears 11a and 11b are provided on the outer sides of the external gears 10a and 10b, respectively. The internal gears 11a and 11b are arranged coaxially with the input wheel 7 so that one end thereof is positioned between the outer tube portion 7a and the inner tube portion 7b of the input wheel 7. An outward flange 12 is formed at the outer end located outside from the outer edge of the casing 2, and the flange 12 is fixed to the end plate 2 a of the casing 2.

  As shown in FIG. 2, the external teeth 13 of the external gears 10a and 10b and the internal teeth 14 of the internal gears 11a and 11b are involute teeth, and the number of teeth of the external teeth 13 is smaller than the number of teeth of the internal teeth 14. The portion meshes with the internal teeth 14.

  As shown in FIG. 1, a seal member 15 is installed between the inner ends of the internal gears 11 a and 11 b and the inner cylindrical portion 7 b of the input wheel 7 to prevent leakage of lubricating oil to the coil portion of the stator 5. It is out.

  A hub shaft 16 is inserted inside the input wheel 7, and the hub shaft 16 and the input wheel 7 are relatively rotatably supported by rolling bearings 17 incorporated inside the eccentric shaft portions 8a and 8b. ing.

  The hub axle 16 is provided with flanges 18a and 18b that are axially opposed to the external gears 10a and 10b. The flanges 18a and 18b are attached to the casing 2 via rolling bearings 19 attached to the outer diameter surfaces thereof. It is supported rotatably.

  Here, the flange 18a provided at the shaft end portion of the hub shaft 16 is fitted into a small diameter shaft portion 16a formed at the shaft end of the hub shaft 16, and is a nut engaged with the small diameter shaft portion 16a by screw engagement. It is fixed by 20 tightening.

  External gears 10a and 10b that revolve while revolving by meshing with the internal gears 11a and 11b between the opposing surfaces of the external gears 10a and 10b and the flanges 18a and 18b that axially face the external gears 10a and 10b. A torque transmission mechanism 21 that absorbs the revolving motion and transmits the rotational motion to the flanges 18a and 18b is incorporated.

  As shown in FIGS. 1 and 3, the torque transmission mechanism 21 has a plurality of pins 22 on the opposite surfaces of the external gears 10a and 10b to the flanges 18a and 18b, and the same circle centered on the axis of the eccentric shaft portions 8a and 8b. The rollers 23 are rotatably fitted to the pins 22 and are inserted into the circular holes 24 formed in the flanges 18a and 18b, and a part of the inner periphery of the circular holes 24 is provided. It is set as the structure made to contact. The inner diameter dimension of the circular hole 24 and the outer diameter dimension of the pin 22 are set so that the radius of the rotation orbit circle drawn by the center of the pin 22 in the circular hole 24 becomes the eccentric amount of the eccentric shaft portions 8a and 8b. Has been.

  In the embodiment, a needle roller bearing is used as the roller 23 from the viewpoint of reducing the radial thickness, but the present invention is not limited to this. For example, any rolling bearing can be adopted regardless of whether the rolling element is a roller or a ball, such as a cylindrical roller bearing, a tapered roller bearing, an angular ball bearing, a four-point contact ball bearing, and a self-aligning roller bearing. it can.

  Contrary to the above, pins may be provided on the flanges 18a and 18b, and circular holes may be formed on the side surfaces of the external gears 10a and 10b. Further, the roller 23 may be omitted, and the pin may be brought into direct contact with a part of the inner periphery of the circular hole. In this case, it is preferable to support the pin rotatably.

  An output wheel 25 is fitted to the end of the hub shaft 16 on the outboard side. The output wheel 25 includes a hub wheel 26 and a bearing inner ring 27. The bearing inner ring 27 has a cylindrical portion 27a at the end, and the cylindrical portion 27a is fitted in the hub wheel 26, and the diameter of the inner ring portion is increased. It is integrated with the hub wheel 26 by caulking. On the other hand, a wheel mounting flange 28 is formed on the outer periphery of the hub wheel 26, and a wheel fixing bolt 29 is mounted on the wheel mounting flange 28.

  The output wheel 25 is configured such that the cylindrical portion 27 a of the bearing inner ring 27 and the hub shaft 16 are coupled by a spline 30 so as to rotate integrally with the hub shaft 16. The output wheel 25 is fixed to the hub shaft 16 by tightening a nut 31 that is screw-engaged with the screw shaft 16 b at the shaft end of the hub shaft 16.

  An outer member 32 is provided outside the output wheel 25, and the output wheel 25 is rotatably supported by double row rolling elements 33 incorporated between the outer member 32 and the output wheel 25.

  The outer member 32 has a vehicle body mounting flange 34 on the outer periphery, and the vehicle body mounting flange 34 is abutted against the side surface of the knuckle 1 on the outboard side and is fixed to the knuckle 1 by tightening bolts 35. . The casing 2 is fixed to the body mounting flange 34.

  The power transmission device shown in the embodiment has the above structure. When the rotor 6 is rotated by supplying power to the coil of the stator 5 of the electric motor 4 shown in FIG. 1, the input wheel 7 rotates together with the rotor 6. The eccentric shaft portions 8a and 8b rotate eccentrically.

  By the eccentric rotation of the eccentric shaft portions 8a and 8b, the external teeth 13 of the external gears 10a and 10b supported by the eccentric shaft portions 8a and 8b are engaged with the internal teeth 14 of the internal gears 11a and 11b one by one. Revolve around 16.

  At this time, since the number of teeth of the external teeth 13 of the external gears 10a and 10b is smaller than the number of teeth of the internal teeth 14 of the internal gears 11a and 11b, the external gears 10a and 10b are input by a difference in the number of teeth from the internal gears 11a and 11b. The wheel 7 rotates in the direction opposite to the rotation direction, and the rotation motion is transmitted to the flanges 18a and 18b via the pin 22, and the hub shaft 16 and the output wheel 25 rotate at a reduced speed.

Here, when the number of teeth of the internal teeth 14 of the internal gears 11a and 11b is Z ₁ and the number of teeth of the external teeth 13 of the external gears 10a and 10b is Z ₂ , the reduction ratio is (Z ₁ −Z ₂ ) / Z. ₂ can be expressed.

  Thus, in the power transmission device shown in the embodiment, the external gears 10a and 10b meshing with the fixed internal gears 11a and 11b by the rotation of the input wheel 7 that rotates integrally with the rotor 6 are one of the input wheels 7. Since the rotation of the internal gears 11a, 11b and the external gears 10a, 10b rotates by the difference in the number of teeth per rotation and the rotation is transmitted to the hub shaft 16 and the output wheel 25 via the torque transmission mechanism 21, the stator 5 and the rotor 6 can be transmitted to the output wheel 25 with a large reduction ratio.

  In addition, since the speed reduction mechanism has a small number of parts including the internal gears 11a and 11b and the external gears 10a and 10b, a small and compact power transmission device can be obtained. As shown in the embodiment, the outer ring part 7a and the inner cylinder part 7b are provided in the input wheel 7, and a part of the internal gears 11a and 11b is accommodated between the outer cylinder part 7a and the inner cylinder part 7b. As a result, the axial length of the power transmission device can be made more compact.

  In the above description of the operation, electric power is supplied to the electric motor 4 to drive the electric motor 4, and the power from the electric motor 4 is transmitted to the output wheel 25 to which the wheels are attached. When decelerating or going down a hill, the power from the wheels may be converted to high rotation and low torque by the deceleration unit and transmitted to the electric motor 4, and the electric motor 4 may generate power. Further, the electric power generated here may be used for the electric motor 4 or other electric devices provided in the vehicle after temporarily storing in the battery.

  The control of the power transmission device shown in the embodiment includes, for example, an accelerator pedal position sensor, a brake depression amount sensor, a vehicle speed sensor, a battery temperature detection sensor, a voltage sensor connected between battery terminals, and a power line from the battery. Electric power is exchanged between the battery and the electric motor via the inverter based on these signals after inputting signals from various sensors such as current sensors and motor rotation position detection sensors installed in the electronic control unit. It is done by adjusting.

  For the control, for example, the number of rotations of the wheels driven by the power transmission device installed at each of the left and right or front and rear, left and right positions is independently controlled according to the steering angle of the steering wheel, thereby turning the vehicle stably. Or the idling of the wheel is detected from the signals of the wheel speed sensors of the front and rear wheels, and the rotational speed of the power transmission device is controlled based on the detection result to stabilize the posture of the vehicle.

  In FIG. 2, the external teeth 13 of the external gears 10a and 10b and the internal teeth 14 of the internal gears 11a and 11b are involute teeth, but as shown in FIG. 4, the external teeth 13 of the external gears 10a and 10b are trochoidal curve tooth shapes. The internal teeth 14 of the internal gears 11a and 11b may be external pins.

  As shown in FIG. 4, when the external teeth 13 of the external gears 10a and 10b are trochoidal curved teeth and the internal teeth 14 of the internal gears 11a and 11b are external pins, the meshing rate can be increased and the teeth can be broken. It is possible to obtain a power transmission device with less durability and excellent durability.

A longitudinal front view showing an embodiment of a power transmission device according to the present invention Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. Sectional drawing which shows the other example of a gear-type reduction mechanism

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Knuckle 2 Casing 4 Electric motor 5 Stator 6 Rotor 7 Input wheel 8a Eccentric shaft part 8b Eccentric shaft part 10a External gear 10b External gear 11a Internal gear 11b Internal gear 13 External tooth 14 Internal tooth 16 Hub shaft 18a Flange 18b Flange 21 Torque transmission Mechanism 22 Pin 23 Roller 24 Circular hole 25 Output wheel 26 Hub wheel 28 Wheel mounting flange 32 Outer member 33 Rolling element 34 Flange

Claims (8)

A casing fixed to the vehicle body side;
An electric motor in which a rotor is rotatably provided in a stator fixed to the inner periphery of the casing;
An input wheel that is incorporated into the rotor and rotates integrally with the rotor, and an eccentric shaft portion is formed at the shaft end; and
An internal gear fixed to the casing and arranged coaxially with the input wheel;
An external gear that is rotatably supported by the eccentric shaft portion of the input wheel and meshes with the internal gear, and has a smaller number of teeth than an internal gear that rotates while revolving by meshing with the internal teeth of the internal gear by rotation of the rotor;
A hub shaft that is inserted into the input wheel and rotatably supported, and has a flange facing the external gear in the axial direction;
A torque transmission mechanism provided between the outer gear and the flange of the hub shaft to absorb the revolution movement of the outer gear and transmit the rotation of the outer gear to the flange;
An output wheel fitted to the shaft end of the hub shaft and prevented from rotating, and having a wheel mounting flange on the outer periphery;
An outer member having a flange for mounting on the vehicle body on the outer periphery, and rotatably supporting the output wheel via a double row rolling element;
A power transmission device comprising:   The power transmission device according to claim 1, wherein the external teeth of the external gear and the internal teeth of the internal gear are involute teeth.   2. The power transmission device according to claim 1, wherein the external teeth of the external gear are trochoidal curved teeth, and the internal teeth of the internal gear are external pins.   In the torque transmission mechanism, a plurality of pins are provided concentrically on one of the opposing surfaces of the external gear and the flange, and each pin is inserted into a circular hole larger than the pin diameter formed on the other of the opposing surfaces. The power transmission device according to any one of claims 1 to 3, comprising a configuration in which each pin is in contact with a part of the inner periphery of each circular hole.   There are two eccentric shaft portions formed on the input wheel, each of the eccentric shaft portions rotatably supports an external gear, each of the internal gears meshed with each external gear is fixed to the casing, and the hub shaft has The power transmission device according to any one of claims 1 to 4, wherein a flange is provided to face each of the eccentric shaft portions, and the torque transmission mechanism is provided between the flange and the facing surface of the external gear.   The power transmission device according to claim 5, wherein the two eccentric shaft portions are provided with a 180 ° phase shift in the circumferential direction.   The power transmission device according to any one of claims 1 to 6, wherein a roller is rotatably fitted to each pin, and each roller is brought into contact with a part of the inner periphery of the circular hole.   The power transmission device according to any one of claims 1 to 7, wherein the input wheel and the hub shaft are relatively rotatably supported by a rolling bearing incorporated inside an eccentric shaft portion of the input wheel.

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