JP2010210049A - Planetary gear mechanism and electrically driven vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planetary gear mechanism and an electrically driven vehicle capable of restraining an exciting force in both rotating direction and radial direction. <P>SOLUTION: The planetary gear mechanism is provided with four pinions 10P, 20P, and the phase of engagement with sun gears 10S, 20S of each of the pinions 10P, 20P and ring gears 10R, 20R is shifted equidistantly, and the relative tooth face shape of engagement with each of the pinions 10P, 20P and the sun gears 10S, 20S or ring gears 10R, 20R are modified in the same direction for the opposed pinions, and modified in the reverse direction for the adjacent pinions. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a planetary gear mechanism and an electric vehicle.

  Patent Document 1 discloses a configuration using a planetary gear mechanism as a reduction device for an in-wheel motor. In the planetary gear mechanism, a technology is known in which the number of teeth of the sun gear and the ring gear is set so as to shift the meshing phases of the pinions with respect to the sun gear and the ring gear at equal intervals, and the vibration level in the rotational direction is suppressed.

JP 2006-188153 A

  However, the method of shifting the phase difference at equal intervals is effective for suppressing vibrations in the rotational direction, but for radial vibrations, vibrations that are plus or minus for one rotation of the carrier with respect to the meshing order Z are obtained. There is a problem that a so-called sideband phenomenon occurs in which the level of the Z + 1 component or the Z-1 order component increases, and vibration increases.

  An object of the present invention is to provide a planetary gear mechanism and an electric vehicle that can suppress both vibrations in the rotational direction and radial direction.

  In the present invention, the engagement phase of each even-numbered pinion is shifted at equal intervals, the relative tooth surface shape of the engagement between each pinion and the sun gear or the ring gear is modified in the same direction between the opposing pinions, and adjacent pinions Then it was corrected in the opposite direction.

  Therefore, in the present invention, both vibrations in the rotational direction and radial direction can be suppressed.

1 is a schematic diagram of an electric vehicle 100 according to a first embodiment. FIG. 2A is a view of the planetary gear mechanism 10 as viewed from the direction of the arrow A, and FIG. It is a figure which shows each pinion of the planetary gear mechanism 10 (20) of Example 1. FIG. Example 1 (a) Schematic diagram of relative tooth surface shape TSP1 of engagement between first pinion 10P1 and sun gear or ring gear, (b) Schematic diagram of relative tooth surface shape of engagement between second pinion 10P2 and sun gear or ring gear FIG. 4C is a schematic diagram of a relative tooth surface shape of meshing between the third pinion 10P3 and the sun gear or the ring gear, and FIG. 6D is a schematic diagram of a relative tooth surface shape of meshing of the fourth pinion 10P4 and the sun gear or the ring gear. (A) Relationship between the order of one planetary gear mechanism and the amplitude of the radial excitation force, and (b) the other of the pinion and the sun gear or ring gear in the same relative tooth shape. It is a relationship diagram between the order of the planetary gear mechanism and the amplitude of the exciting force in the radial direction. Example 1 (a) Relationship diagram between the order of the planetary gear mechanism 10 and the amplitude of the radial excitation force, (b) Relationship diagram between the order of the planetary gear mechanism 20 and the amplitude of the excitation force in the radial direction It is. Example 2 (a) Schematic diagram of relative tooth surface shape TSP1 of engagement between first pinion 10P1 and sun gear or ring gear, (b) Schematic diagram of relative tooth surface shape of engagement between second pinion 10P2 and sun gear or ring gear FIG. 4C is a schematic diagram of a relative tooth surface shape of meshing between the third pinion 10P3 and the sun gear or the ring gear, and FIG. 6D is a schematic diagram of a relative tooth surface shape of meshing of the fourth pinion 10P4 and the sun gear or the ring gear. Example 2 (a) Relationship diagram between the order of the planetary gear mechanism 10 and the amplitude of the radial excitation force, (b) Relationship diagram between the order of the planetary gear mechanism 20 and the amplitude of the excitation force in the radial direction It is. FIG. 6 is a schematic diagram illustrating a drive system of an electric vehicle 100 according to a third embodiment. FIG. 3 is a diagram showing a state in which excitation forces FE10 and FE20 of radial vibrations of two planetary gear mechanisms 10 and 20 are in opposite phases.

  Hereinafter, modes for carrying out the present invention will be described based on each embodiment shown in the drawings.

FIG. 1 is a schematic diagram of an electric vehicle 100 according to the first embodiment. The electric vehicle 100 according to the first embodiment is a front wheel drive type electric vehicle in which front wheels (drive wheels) FR and FL are driven by two in-wheel motors 1 and 2.
The in-wheel motor 1 includes a planetary gear mechanism 10 (see FIG. 2) as a reduction gear, and the in-wheel motor 2 includes a planetary gear mechanism 20 (see FIG. 2) as a reduction gear. The two planetary gear mechanisms 10 and 20 have the same shape (same gear specifications, substantially the same relative tooth surface shape).

  As shown in FIG. 2 (a), the planetary gear mechanism 10 is a single pinion type planetary gear mechanism having a sun gear 10S, a ring gear 10R, and a carrier 10C that rotatably supports four pinions 10P engaged therewith. The ring gear 10R is fixed to the housing, the sun gear 10S rotates integrally with the input side (motor side), and the carrier 10C rotates integrally with the output shaft (wheel side).

  As shown in FIG. 2 (b), the planetary gear mechanism 20 is a single pinion planetary gear mechanism having a sun gear 20S, a ring gear 20R, and a carrier 20C that rotatably supports four pinions 20P engaged therewith. The ring gear 20R is fixed to the housing, the sun gear 10S rotates integrally with the input side (motor side), and the carrier 20C rotates integrally with the output side (wheel side).

  The sun gears 10S and 20S and the ring gears 10R and 20R have the meshing phases of the pinions 10P and 20P with the sun gears 10S and 20S or the ring gears 10R and 20R deviated at equal intervals by 1/4 pitch with reference to one pinion 10P and 20P. In this way, the number of teeth is set. Thereby, the exciting force in the rotation direction can be suppressed, and the amplitude of vibration can be reduced.

  In the first embodiment, when the electric vehicle 100 moves forward (in the direction of the arrow in FIG. 1), the planetary gear mechanism 10 of the right front wheel FR rotates in the clockwise direction (CW) in the direction of arrow A. On the other hand, the planetary gear mechanism 20 of the left front wheel FL rotates counterclockwise (CCW) in the direction of arrow B. That is, when the vehicle travels, the two planetary gear mechanisms 10 and 20 rotate in opposite directions with respect to the respective arrows.

Next, the relative tooth surface shape of the engagement between the pinions 10P and 20P of the first embodiment and the sun gear or the ring gear will be described. Since the planetary gear mechanism 10 and the planetary gear mechanism 20 have the same shape, only the planetary gear mechanism 10 will be described.
As shown in FIG. 3, when the four pinions 10P of the planetary gear mechanism 10 are placed in order 10P1, 10P2, 10P3, 10P4 in the clockwise direction, in the first embodiment, each pinion 10P1, 10P2, 10P3, 10P4 and the sun gear Alternatively, the relative tooth surface shape of meshing with the ring gear is subjected to the same amount of pressure angle modification that is in the same direction between opposing pinions and in the opposite direction between adjacent pinions. “Pressure angle modification” refers to modification in the direction of toothpaste, which involves modification of releasing the tooth tip and modification of releasing the tooth base.

  4 (a) to 4 (d) are schematic views showing the relative tooth surface shapes of the pinions 10P1, 10P2, 10P3, 10P4 and the sun gears or ring gears after pressure angle adjustment, and the shapes are indicated by contour lines. ing. In the first pinion 10P1 shown in FIG. 4 (a), a relative tooth surface shape TSP1 that comes into contact with the tooth base with respect to the sun gear 10S and the ring gear 10R is obtained by modifying the tooth tip side. In the second pinion 10P2 shown in FIG. 4 (b), a tooth surface shape TSP2 that is in contact with the tooth tip with respect to the sun gear 10S and the ring gear 10R is obtained by modifying the tooth base side. In the third pinion 10P3 shown in FIG. 4 (c), a tooth surface shape TSP3 is obtained that is in contact with the tooth base with respect to the sun gear 10S and the ring gear 10R by the modification that releases the tooth tip side. In the fourth pinion 10P4 shown in FIG. 4 (d), the tooth surface shape TSP4 is formed so as to come into contact with the tooth tip with respect to the sun gear 10S and the ring gear 10R by the modification that allows the tooth base side to escape.

Next, the operation will be described.
[Rotation direction vibration suppression action]
Conventionally, in a planetary gear mechanism, vibrations in the rotational direction are suppressed by setting the number of teeth of the sun gear and the ring gear so as to shift the meshing phases of the pinions with respect to the sun gear and the ring gear at equal intervals.

  However, in the planetary gear mechanism in which the phase difference is shifted at equal intervals, frequency modulation occurs in radial vibration, and the Z + 1-order component or Z-1 of vibration that is plus or minus for one rotation of the carrier with respect to the meshing order Z There is a problem that a so-called sideband phenomenon occurs in which the level of the next component increases, and vibration in that direction increases. Hereinafter, the Z + 1 order component and the Z-1 order component of the vibration generated by the sideband phenomenon are referred to as Z + 1 order and Z-1 order sidebands.

  Whether the Z-1 order or Z + 1 order sideband appears depends on the rotation direction. If the direction of meshing phase is different from the rotation direction of the carrier, a Z + 1 order sideband is generated, and if the direction of meshing phase is different from the direction of rotation of the carrier, the Z-1 order is Sidebands are generated.

  On the other hand, in the planetary gear mechanism 10 of the first embodiment, the first pinion 10P1 and the third pinion 10P3 are modified to release the tooth tip side so that the relative tooth surface shape of the engagement with the sun gear or the ring gear comes into contact with the tooth root. In the 2nd pinion 10P2 and the 4th pinion 10P4, the pinion facing each other (10P1) is made by modifying the tooth base side so that the relative tooth surface shape of the engagement with the sun gear or the ring gear comes into contact with the tooth tip. And 10P3, 10P2 and 10P4), the modification direction is the same direction, and adjacent pinions (10P1 and 10P2, 10P2 and 10P3, 10P3 and 10P4, 10P4 and 10P1) have the modification direction opposite. The same applies to the planetary gear mechanism 20.

As a result, amplitude modulation occurs in the excitation force of the radial vibration, and both Z + 1 order and Z-1 order sidebands are generated. Further, the amplitude is reduced to about ½.
That is, in the planetary gear mechanisms 10 and 20 according to the first embodiment, the Z + 1-order sideband and the Z-1st-order sideband are approximately the same regardless of the rotation direction, and one sideband is generated. Because it is generated with an amplitude of / 2, the level of vibration in the radial direction is suppressed compared to a planetary gear mechanism in which one of the Z + 1-order or Z-1-order sidebands appears and the phase difference is shifted at equal intervals. it can.

[Buzzing sound suppression effect]
As shown in the first embodiment, in an electric vehicle using planetary gear mechanisms having the same shape on the left and right as a reduction device for an in-wheel motor, planetary gears in which the phase difference is shifted at equal intervals to suppress vibration in the rotational direction When the mechanism is used, one planetary gear mechanism generates a Z-1st order sideband, and the other planetary gear mechanism generates a Z + 1st order sideband. At this time, because the Z + 1 order sideband and the Z-1 order sideband have similar sound frequencies, the sounds interfere with each other, and the sound changes at a frequency corresponding to the frequency difference between the sounds. A so-called “groaning sound” is generated, which gives the passenger discomfort.

  FIG. 5 shows, as a comparative example of the first embodiment, a planetary gear mechanism in which the phase difference is shifted to the left and right of the drive wheel at equal intervals as a reduction device, and the relative tooth surface shape of the engagement between each pinion and the sun gear or ring gear is the same. Is the relationship between the order and the amplitude of exciting force in the radial direction. As shown in FIG. 5, in the planetary gear mechanism of the right front wheel, a Z + 1-order side band having a large amplitude is generated as shown in FIG. 5 (a), and in the planetary gear mechanism of the left front wheel, FIG. As can be seen, a Z-1 order sideband with a large amplitude is generated.

  On the other hand, in the electric vehicle 100 of the first embodiment, as shown in FIG. 6 (a), the radial excitation force of the planetary gear mechanism 10 is Z + 1 as compared with the case of FIG. 5 (a). The next component is halved, and the Z-1 order component with the same amplitude appears. Similarly, as shown in FIG. 6B, the radial excitation force of the planetary gear mechanism 20 has a Z-1 order component halved compared to the case of FIG. Z + 1 order component appears.

  Therefore, in the two planetary gear mechanisms 10 and 20, a Z-1 order sideband and a Z + 1 order sideband in the radial direction are generated, and the sum of the amplitudes of the left and right wheels at each order is shown in FIG. The Z + 1 order and Z-1 order sidebands shown in Fig. 1 are almost equal, but because there is actually a phase difference between the left and right wheels, the superimposed Z-1 order sound and Z + 1 order sound The level is smaller than in the comparative example. For this reason, in the planetary gear mechanisms 10 and 20 of the first embodiment, the level of the beat sound generated by the interference of the vibration noises of the planetary gear mechanisms 10 and 20 with respect to the comparative example can be suppressed.

[Cost reduction effect]
Japanese Patent Application Laid-Open No. 2008-37133 discloses a technique for suppressing the generation of beat noise by configuring the left and right in-wheel motor left and right reduction devices with three-shaft gears and changing the number of teeth of the left and right three-shaft gears. It is disclosed. However, this prior art requires different speed reducers on the left and right, leading to an increase in cost due to an increase in the number of parts.

  On the other hand, in the first embodiment, the planetary gear mechanisms 10 and 20 having the same shape (same gear specifications and substantially the same relative tooth surface shape) are used as the reduction gears of the in-wheel motors 1 and 2, and therefore, compared with the above-described conventional technology. Thus, the cost can be reduced by reducing the number of parts.

Next, the effect will be described.
The planetary gear mechanisms 10 and 20 and the electric vehicle 100 of the first embodiment have the effects listed below.
(1) Four pinions 10P and 20P are provided, and the meshing phases of the pinions 10P and 20P with the sun gears 10S and 20S and the ring gears 10R and 20R are shifted at equal intervals, so that each pinion 10P and 20P meshes with the sun gear or the ring gear. The relative tooth surface shape was modified in the same direction between opposing pinions, and modified in the opposite direction between adjacent pinions. Thereby, both the vibration in the rotational direction and the radial direction can be suppressed.

  (2) Since the tooth profile modification is a pressure angle modification, it is possible to realize a relative tooth profile that reduces the radial vibration by a relatively easy modification of the tooth profile.

  (3) In the electric vehicle 100 having the in-wheel motors 1 and 2 on the front wheels FR and FL, the planetary gear mechanisms 10 and 20 are applied as the reduction gears of the in-wheel motors 1 and 2, so the planetary gear mechanisms 10 and 20 The beat sound caused by the interference of the generated sound can be reduced, and the discomfort given to the passenger can be reduced.

  The second embodiment is an example in which the modification direction of the tooth surface shape of the pinion is different from that of the first embodiment. In addition, about the part which is common in Example 1, it represents with the same name and the same code | symbol, and abbreviate | omits description.

  In the second embodiment, the sun gears 10S and 20S, the ring gears 10R and 20R and the pinions 10P and 20P of the planetary gear mechanisms 10 and 20 are helical gears, and the relative tooth surfaces of the meshes between the pinions 10P1, 10P2, 10P3, and 10P4 and the sun gear or the ring gear are used. The shape is subjected to the same amount of twist angle modification in the same direction between opposing pinions and in the opposite direction between adjacent pinions. “Twist angle modification” is correction in the tooth width direction, and refers to a modification that releases the meshing start side of the tooth width and a modification that releases the meshing end side.

  FIGS. 7A to 7D are schematic views showing the relative tooth surface shapes of the meshes between the pinions and the sun gears or ring gears after the twist angle correction, and the shapes are indicated by contour lines. In the first pinion 10P1 shown in FIG. 7 (a), the relative tooth surface shape TSP1 near the end of the engagement is obtained by the modification that releases the engagement initial side. In the second pinion 10P2 shown in FIG. 7 (b), the relative tooth surface shape TSP2 that comes into contact with the beginning of the engagement is obtained by the modification that releases the engagement end side. In the third pinion 10P3 shown in FIG. 7C, the relative tooth surface shape TSP3 near the end of the engagement is obtained by the modification that releases the engagement initial side. In the fourth pinion 10P4 shown in FIG. 7 (d), the relative tooth surface shape TSP4 that comes into contact with the beginning of meshing is obtained by the modification that releases the meshing end side.

Next, the operation will be described.
[Rotation direction vibration suppression action]
In the planetary gear mechanism 10 according to the second embodiment, the first pinion 10P1 and the third pinion 10P3 are first engaged to be engaged, and the second pinion 10P2 and the fourth pinion 10P4 are subjected to end-of-engagement modification so that the opposing pinions (10P1 And 10P3, 10P2 and 10P4), the modification direction is the same direction, and adjacent pinions (10P1 and 10P2, 10P2 and 10P3, 10P3 and 10P4, 10P4 and 10P1) have the modification direction opposite. The same applies to the planetary gear mechanism 20.

As a result, amplitude modulation occurs in the excitation force of the radial vibration, and both Z + 1 order and Z-1 order sidebands are generated. Further, the amplitude is reduced to about ½.
For this reason, as shown in FIG. 8 (a), the radial excitation force of the planetary gear mechanism 10 of the right front wheel FR has a Z + 1 order component halved compared to the case of FIG. 5 (a), The Z-1 order component of almost the same level appears. Similarly, as shown in FIG. 8 (b), the excitation force in the radial direction of the planetary gear mechanism 20 of the left front wheel FL is half that of the Z-1 order component compared to the case of FIG. 5 (b), A Z + 1 order component of almost the same level appears.

  Therefore, in the planetary gear mechanisms 10 and 20 of the second embodiment, the level of vibration in the radial direction can be suppressed as in the first embodiment. Further, in the electric vehicle 100 according to the second embodiment, as in the first embodiment, it is possible to suppress the level of the beat sound generated by the interference of the vibration sounds of the planetary gear mechanisms 10 and 20.

Next, the effect will be described.
The planetary gear mechanisms 10 and 20 and the electric vehicle 100 of the second embodiment have the following effects in addition to the effects (1) and (3) of the first embodiment.
(4) Since the tooth surface is modified with the twist angle, it is possible to realize a tooth surface shape that reduces vibration in the radial direction with relatively easy tooth surface modification.

  The third embodiment is an example in which the roaring sound is canceled by correcting the rotation angles of the in-wheel motors 1 and 2. In addition, about the part which is common in Example 1, it represents with the same name and the same code | symbol, and abbreviate | omits description.

FIG. 9 is a schematic diagram illustrating a drive system of the electric vehicle 100 according to the third embodiment.
The battery 101 supplies power to the inverter 102. The inverter 102 controls the current and voltage of the in-wheel motors 1 and 2 connected to the front wheels FR and FL to generate drive torque.

The accelerator sensor 103 detects the accelerator opening. The shift sensor 104 detects a shift position. The signal of each sensor is sent to the control unit 105.
The control unit 105 calculates a target motor torque based on signals from the accelerator sensor 103 and the shift sensor 104, and controls the inverter 102 based on the target motor torque.

The in-wheel motors 1 and 2 include resolvers 106 and 107 that detect a rotation angle of a rotor (not shown).
The control unit (rotation angle correction means) 105 monitors the rotation angles of the in-wheel motors 1 and 2 detected by the resolvers 106 and 107, and the vibration waveforms of the left and right planetary gear mechanisms 10 and 20 maintain an inverse phase relationship. As described above, the driving force control for correcting the rotation angles of the left and right front wheels FL and FR is performed.

Next, the operation will be described.
[Buzzing sound canceling action]
The relationship between the phase of the two planetary gear mechanisms 10 and 20 and the radial excitation force varies depending on the difference between the inner and outer rings generated during turning and the difference in rotational speed caused by slip. At this time, the closer the Z + 1-order sideband and the Z-1th-order sideband are, the louder the beating sound.

In the third embodiment, therefore, the number of rotations of both in-wheel motors 1 and 2 is monitored using resolvers 106 and 107 that detect the rotation angles of both in-wheel motors 1 and 2, and the vibrations of the two planetary gear mechanisms 10 and 20 are monitored. The rotations of both in-wheel motors 1 and 2 are adjusted so that the waveforms always maintain an antiphase relationship (see FIG. 10).
For this reason, the suppression effect of the roaring sound can be enhanced by always canceling out the Z-1st order sideband and the Z + 1st order sideband.

Here, the correction of the rotation angle may be performed only during steady running. “During steady driving” refers to a state where the vehicle is traveling straight or turning at a substantially constant speed. This is because, during steady running, the rotational angle of the left and right drive wheels FL, FR is small compared to a transient state such as acceleration / deceleration, making it easy to correct the rotation angle. Furthermore, if the driving force is corrected in a transient state, the vehicle behavior may be disturbed.
In the third embodiment, the resolvers 106 and 107 are used as means for monitoring the rotation angle of the in-wheel motors 1 and 2. Since the resolver is an essential configuration for driving control of the motor in the electric vehicle, the cost does not increase due to the addition of a new configuration.

Next, the effect will be described.
The planetary gear mechanisms 10 and 20 and the electric vehicle 100 of the third embodiment have the following effects in addition to the effects (1) and (3) of the first embodiment.
(5) The control unit 105 corrects the rotation angle of the left front wheel FL and the right front wheel FR so that the radial excitation force waveforms of the two planetary gear mechanisms 10 and 20 are in opposite phases, so that the beat noise is suppressed. The effect can be enhanced.

(Other examples)
The best mode for carrying out the present invention has been described above based on the embodiments. However, the specific configuration of the present invention is not limited to the embodiments and is within the scope of the invention. Any design changes are included in the present invention.

  For example, in the example, pressure angle modification and torsion angle modification were described as examples of tooth surface modification, but Z + 1 order component and Z-1 order component are generated at the same level even in other tooth surface modification. It is included in the present invention that the modification to be performed is performed at each pinion position.

In the embodiment, the number of pinions is four, but the number of pinions may be an even number of four or more.
The motor is not limited to an in-wheel motor.
The present invention can also be applied to a rear wheel drive vehicle.

FL Left front wheel (drive wheel)
FR Right front wheel (drive wheel)
1,2 In-wheel motor
10,20 Planetary gear mechanism
10P, 20P pinion
105 Control unit (rotation angle correction means)

Claims (5)

Provide an even number of pinions,
Shift the meshing phase of each pinion to the sun gear and ring gear at equal intervals,
A planetary gear mechanism characterized in that the relative tooth surface shape of the engagement between each pinion and a sun gear or ring gear is modified in the same direction between opposing pinions and in the opposite direction between adjacent pinions. The planetary gear mechanism according to claim 1,
The planetary gear mechanism according to claim 1, wherein the modification is a pressure angle modification. The planetary gear mechanism according to claim 1,
The planetary gear mechanism according to claim 1, wherein the modification is a twist angle modification. In an electric vehicle having a reduction gear between each drive wheel and each motor,
An electric vehicle characterized in that the planetary gear mechanism according to any one of claims 1 to 3 is applied as the reduction gear. The electric vehicle according to claim 4,
An electric vehicle comprising rotation angle correction means for correcting the rotation angle of the left and right drive wheels so that the radial excitation force waveforms of the left and right planetary gear mechanisms are in opposite phases.

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