Unit

Abstract

[Problem] To reduce the radial dimension of a unit and to improve sound vibration performance when the radial dimension of the unit has been reduced. [Solution] This unit comprises: a first motor; a second motor; a first planetary gear mechanism connected to the first motor; a second planetary gear mechanism connected to the second motor; and a housing that accommodates the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism. The first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism are coaxially arranged. The rotation phase of a first pinion gear with respect to a first ring gear of the first planetary gear mechanism and the rotation phase of a second pinion gear with respect to a second ring gear of the second planetary gear mechanism are shifted from each other.

Description

unit

[0001] The present invention relates to a unit.

[0002] Patent Document 1 discloses a vehicle drive device (unit) that has a pair of rotating electric machines and a pair of planetary gear mechanisms and independently drives left and right wheels.

[0003] Japanese Patent Application Laid-Open No. 2020-139577

[0004] However, in the vehicle drive device of Patent Document 1, a gear pair is provided to transmit the driving force from the pair of rotating electric machines to the left and right wheels, respectively, which may increase the size of the vehicle drive device.

[0005] The present invention aims to reduce the radial dimensions of a unit and to improve sound vibration performance when the radial dimensions of the unit are reduced.

[0006] According to one aspect of the present invention, a unit includes a first motor, a second motor, a first planetary gear mechanism connected to the first motor, a second planetary gear mechanism connected to the second motor, and a housing that accommodates the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism, wherein the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism are arranged coaxially, and the rotational phase of a first pinion gear relative to a first ring gear of the first planetary gear mechanism and the rotational phase of a second pinion gear relative to a second ring gear of the second planetary gear mechanism are configured to be offset.

[0007] According to one aspect of the present invention, the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism are arranged coaxially, so that the components are not arranged side by side in the radial direction. This allows the radial dimension of the unit to be reduced. Furthermore, the first ring gear of the coaxially arranged first planetary gear mechanism and the second ring gear of the second planetary gear mechanism are configured to have a rotational phase offset, so the positions of the peaks of the vibration waveform generated by the rotation of the pinion gear can be shifted. This prevents the peaks of the vibration waveform from overlapping and amplifying vibration, thereby improving sound and vibration performance. This allows the radial dimension of the unit to be reduced, and also improves sound and vibration performance when the radial dimension of the unit is reduced.

[0008] Fig. 1 is a skeleton diagram illustrating an overview of a unit according to an embodiment of the present invention. Fig. 2 is a structural diagram illustrating a first ring gear of a first planetary gear mechanism. Fig. 3 is a structural diagram illustrating a second ring gear of a second planetary gear mechanism. Fig. 4 is a structural diagram illustrating a state in which the first ring gear of the first planetary gear mechanism and the second ring gear of the second planetary gear mechanism are overlapped in the direction of the rotation axis.

[0009] A drive unit 1 as a unit according to an embodiment of the present invention will be described below with reference to the drawings.

[0010] First, the overall configuration of the drive unit 1 will be described with reference to Fig. 1. Fig. 1 is a skeleton diagram for explaining the outline of the drive unit 1.

[0011] The drive unit 1 is applied to a vehicle 100 and rotates a pair of drive wheels 2 of the vehicle 100. The drive unit 1 includes a first motor 10, a second motor 20, a first planetary gear mechanism 30, a second planetary gear mechanism 40, and a housing 50.

[0012] The first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 are arranged coaxially. "Coaxial arrangement" means that the rotation centers are aligned. In other words, when multiple elements are arranged coaxially, the multiple elements are configured to overlap each other when viewed from the direction of the rotation axis. This means that the components are not arranged side by side in the radial direction, making it possible to reduce the radial dimensions of the drive unit 1.

[0013] The drive unit 1 transmits the output torque of the first motor 10 to one of the drive wheels 2 and transmits the output torque of the second motor 20 to the other drive wheel 2, thereby driving a pair of drive wheels 2 (left and right in this case). The drive unit 1 is capable of independently controlling the output torque of the first motor 10 and the output torque of the second motor 20.

[0014] The first motor 10 is housed in a housing 50. The first motor 10 is electrically connected to a battery (not shown) outside the drive unit 1 via an inverter (not shown), and functions as an electric motor by receiving power from the battery. The first motor 10 can also function as a generator. The first motor 10 has a rotor 11 and a stator 12.

[0015] The rotor 11 has a motor shaft 11a and is rotatably supported by the housing 50 via bearings (not shown). The stator 12 is fastened to the inner wall of the housing 50 by a plurality of bolts (not shown).

[0016] The second motor 20 is housed in the housing 50. The second motor 20 is electrically connected to a battery outside the drive unit 1 via an inverter (not shown), and functions as an electric motor by receiving power from the battery. The second motor 20 can also function as a generator. The second motor 20 has a rotor 21 and a stator 22.

[0017] The rotor 21 has a motor shaft 21a and is rotatably supported by the housing 50 via bearings (not shown). The stator 22 is fastened to the inner wall of the housing 50 by a plurality of bolts (not shown).

[0018] The first planetary gear mechanism 30 is accommodated in the housing 50. The first planetary gear mechanism 30 is connected to the first motor 10. The first planetary gear mechanism 30 has a sun gear 31 as a first sun gear, a plurality of pinion gears 32 as first pinion gears, a carrier 33 as a first carrier, and a ring gear 34 as a first ring gear.

[0019] The sun gear 31 is connected to the motor shaft 11 a of the first motor 10. The output torque of the first motor 10 is transmitted to the sun gear 31 via the motor shaft 11 a. The sun gear 31 is in mesh with a plurality of pinion gears 32.

[0020] The rotation of the sun gear 31 is transmitted to the pinion gears 32, which rotate on their own axes and revolve around the sun gear 31. The pinion gears 32 are in mesh with a ring gear .

[0021] The carrier 33 is rotatably supported by the housing 50 via bearings (not shown). The carrier 33 rotates as the pinion gear 32 revolves around the sun gear 31. The rotation of the carrier 33 is transmitted to the drive wheels 2 via the drive shaft 2a.

[0022] The ring gear 34 is fixed to the inner wall of the housing 50 by a spline structure 35. The ring gear 34 may be fastened to the inner wall of the housing 50 by a plurality of bolts (not shown).

[0023] The second planetary gear mechanism 40 is accommodated in the housing 50. The second planetary gear mechanism 40 is connected to the second motor 20. The second planetary gear mechanism 40 has a sun gear 41 as a second sun gear, a plurality of pinion gears 42 as second pinion gears, a carrier 43 as a second carrier, and a ring gear 44 as a second ring gear.

[0024] The sun gear 41 is connected to the motor shaft 21a of the second motor 20. The output torque of the second motor 20 is transmitted to the sun gear 41 via the motor shaft 21a. The sun gear 41 is in mesh with a plurality of pinion gears 42.

[0025] The rotation of the sun gear 41 is transmitted to the pinion gears 42, which rotate on their own axes and revolve around the sun gear 41. The pinion gears 42 are in mesh with a ring gear 44.

[0026] The carrier 43 is rotatably supported by the housing 50 via bearings (not shown). The carrier 43 rotates as the pinion gear 42 revolves around the sun gear 41. The rotation of the carrier 43 is transmitted to the drive wheels 2 via the drive shaft 2a.

[0027] The ring gear 44 is fixed to the inner wall of the housing 50 by a spline structure 45. The ring gear 44 may be fastened to the inner wall of the housing 50 by a plurality of bolts (not shown).

[0028] The housing 50 is composed of one or more members. That is, the housing 50 may be composed of a plurality of members. The housing 50 accommodates the first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 therein. The housing 50 is fixed to the vehicle 100 so as not to be rotatable.

[0029] Next, the arrangement of the ring gear 34 of the first planetary gear mechanism 30 and the ring gear 44 of the second planetary gear mechanism 40 will be described with reference to Figures 2 to 4. Figure 2 is a configuration diagram illustrating the ring gear 34. Figure 3 is a configuration diagram illustrating the ring gear 44. Figure 4 is a configuration diagram showing the ring gear 34 and the ring gear 44 overlapped in the direction of the rotation axis.

[0030] 2, the ring gear 34 of the first planetary gear mechanism 30 has an internal gear 34a. The internal gear 34a is formed in an annular shape on the inner periphery of the ring gear 34 by alternately providing teeth 34b and tooth grooves 34c.

[0031] 3, the ring gear 44 of the second planetary gear mechanism 40 has an internal gear 44a. The internal gear 44a is formed in an annular shape on the inner periphery of the ring gear 44 by alternately providing teeth 44b and tooth grooves 44c.

[0032] The circular pitch of the internal gear 34a of the ring gear 34 is set to be equal to the circular pitch of the internal gear 44a of the ring gear 44. The "circular pitch" refers to the distance between the teeth 34b (tooth 44b) and the width of the tooth gap 34c (tooth gap 44c).

[0033] 4, when viewed from the direction of the rotation axis, the teeth 34b of the internal gear 34a of the ring gear 34 of the first planetary gear mechanism 30 are configured to have portions that overlap with tooth grooves 44c of the internal gear 44a of the ring gear 44 of the second planetary gear mechanism 40. Therefore, even if the pinion gears 32 and 42 revolve and are positioned at the same circumferential angle at the same time, the internal gear 34a of the ring gear 34 and the internal gear 34a of the ring gear 44 are not in the same rotational phase because the angles between them are misaligned.

[0034] The "rotational phase" refers to the timing at which the pinion gear 32 and the ring gear 34 mesh together (the timing at which the pinion gear 42 and the ring gear 44 mesh together). In other words, "the rotational phase is shifted" means that in the left and right planetary gear mechanisms 30, 40, the timing at which the pinion gear 32 and the ring gear 34 mesh together is shifted from the timing at which the pinion gear 42 and the ring gear 44 mesh together.

[0035] In this way, the rotational phase of the pinion gear 32 relative to the ring gear 34 of the first planetary gear mechanism 30 and the rotational phase of the pinion gear 42 relative to the ring gear 44 of the second planetary gear mechanism 40 are configured to be shifted.

[0036] Therefore, by shifting the rotational phase between the first planetary gear mechanism 30 and the second planetary gear mechanism 40, the positions of the peaks of the vibration waveforms generated by the rotation of the pinion gears 32, 42 in both planetary gear mechanisms 30, 40 are shifted. Because the first planetary gear mechanism 30 and the second planetary gear mechanism 40 are arranged coaxially, if the positions of the peaks of the vibration waveforms are aligned, the vibrations will be amplified due to the overlap of the peaks of the vibration waveforms because both planetary gear mechanisms 30, 40 are aligned in the direction of the rotation axis. However, by shifting the positions of the peaks of the vibration waveforms, the amplification of vibrations can be suppressed, and sound and vibration performance can be improved.

[0037] Furthermore, in order to obtain the effect of suppressing the amplification of vibration and improving noise and vibration performance, the peak position of the vibration waveform can be shifted by the simple method of shifting the positions of the teeth 34b, 42b of the ring gears 34, 44, which has the advantage of eliminating the need for complicated controls, etc.

[0038] 4, when viewed from the direction of the rotation axis, the central portions of the teeth 34b of the internal gear 34a of the ring gear 34 are configured to have portions that overlap with the central portions of the tooth grooves 44c of the internal gear 44a of the ring gear 44. In other words, the teeth 44b of the internal gear 44a of the ring gear 44 are located in the center between adjacent pairs of teeth 34b of the internal gear 34a of the ring gear 34. Furthermore, the teeth 34b of the internal gear 34a of the ring gear 34 are located in the center between adjacent pairs of teeth 44b of the internal gear 44a of the ring gear 44.

[0039] In this case, overlapping the center of the tooth 34b with the center of the tooth groove 44c increases the offset between the teeth 34b, 42b of the two ring gears 34, 44. A larger offset further reduces the amplification of vibration, thereby improving noise and vibration performance.

[0040] Here, it is possible to shift the positions of the teeth 34b, 44b of the ring gears 34, 44 by making the circular pitch of the ring gear 34 different from the circular pitch of the ring gear 44, but in that case, the difficulty of designing both planetary gear mechanisms 30, 40 increases when rotating both drive wheels 2 in the same way.

[0041] In contrast, in the drive unit 1, the circular pitch of the internal gear 34a of the ring gear 34 is set to be equal to the circular pitch of the internal gear 44a of the ring gear 44. By designing the circular pitches to be equal, the stop points and spline positions of the ring gears 34, 44 can be adjusted so that the teeth 34b, 42b are misaligned during assembly, thereby making it possible to reduce the difficulty of the design.

[0042] The configuration and effects of the present embodiment will now be described.

[0043] (1) The drive unit 1 comprises a first motor 10, a second motor 20, a first planetary gear mechanism 30 connected to the first motor 10, a second planetary gear mechanism 40 connected to the second motor 20, and a housing 50 that accommodates the first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40. The first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 are arranged coaxially, and are configured so that the rotational phase of the pinion gear 32 relative to the ring gear 34 of the first planetary gear mechanism 30 is shifted from the rotational phase of the pinion gear 42 relative to the ring gear 44 of the second planetary gear mechanism 40.

[0044] With this configuration, the first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 are arranged coaxially, so that the components are not arranged side by side in the radial direction, thereby enabling the radial dimension of the drive unit 1 to be reduced.

[0045] Furthermore, by shifting the rotational phases of the first planetary gear mechanism 30 and the second planetary gear mechanism 40 by structural design or control, the positions of the peaks of the vibration waveforms generated by the rotation of the pinion gears 32, 42 in both planetary gear mechanisms 30, 40 are shifted. Because the first planetary gear mechanism 30 and the second planetary gear mechanism 40 are arranged coaxially, if the positions of the peaks of the vibration waveforms are aligned, the vibrations will be amplified due to the overlap of the peaks of the vibration waveforms because both planetary gear mechanisms 30, 40 are aligned in the direction of the rotation axis. However, by shifting the positions of the peaks of the vibration waveforms, the amplification of vibrations can be suppressed, and sound and vibration performance can be improved.

[0046] (2) The drive unit 1 comprises a first motor 10, a second motor 20, a first planetary gear mechanism 30 connected to the first motor 10, a second planetary gear mechanism 40 connected to the second motor 20, and a housing 50 that accommodates the first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40. The first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 are arranged coaxially, and are configured so that, when viewed from the direction of the rotation axis, the teeth 34b of the internal gear 34a of the ring gear 34 of the first planetary gear mechanism 30 have a portion that overlaps with the tooth groove 44c of the internal gear 44a of the ring gear 44 of the second planetary gear mechanism 40.

[0047] With this configuration, the first motor 10, the second motor 20, the first planetary gear mechanism 30, and the second planetary gear mechanism 40 are arranged coaxially, so that the components are not arranged side by side in the radial direction, thereby enabling the radial dimension of the drive unit 1 to be reduced.

[0048] Furthermore, in order to obtain the effect of suppressing the amplification of vibration and improving noise and vibration performance, the peak position of the vibration waveform can be shifted by the simple method of shifting the positions of the teeth 34b, 42b of the ring gears 34, 44, which has the advantage of eliminating the need for complicated controls, etc.

[0049] (3) When viewed from the direction of the rotation axis, the center portions of the teeth 34b of the internal gear 34a of the ring gear 34 have portions that overlap with the center portions of the tooth grooves 44c of the internal gear 44a of the ring gear 44.

[0050] According to this configuration, overlapping the center of the tooth 34b with the center of the tooth groove 44c increases the offset between the teeth 34b, 42b of the two ring gears 34, 44. A larger offset further reduces the amplification of vibration, thereby improving noise and vibration performance.

[0051] (4) The circular pitch of the internal gear 34 a of the ring gear 34 is set to be equal to the circular pitch of the internal gear 44 a of the ring gear 44 .

[0052] With this configuration, it is possible to shift the positions of the teeth 34b, 44b of the ring gears 34, 44 by making the circular pitch of the ring gear 34 (the distance between the teeth 34b (the width of the tooth gap 34c)) different from the circular pitch of the ring gear 44 (the distance between the teeth 44b (the width of the tooth gap 44c)). However, in this case, it becomes more difficult to design both planetary gear mechanisms 30, 40 in order to rotate both drive wheels 2 in the same way. By designing the circular pitches to be equal, the stop points and spline positions of the ring gears 34, 44 can be adjusted so that the teeth 34b, 42b are shifted during assembly, thereby making it possible to reduce the difficulty of the design.

[0053] Although an embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0054] In the above embodiment, the rotational phase of the pinion gear 32 relative to the ring gear 34 and the rotational phase of the pinion gear 42 relative to the ring gear 44 are shifted by the simple method of shifting the positions of the teeth 34b, 42b of the ring gears 34, 44. Alternatively, the rotational phase of the pinion gear 32 relative to the ring gear 34 and the rotational phase of the pinion gear 42 relative to the ring gear 44 may be shifted by control without shifting the positions of the teeth 34b, 42b of the ring gears 34, 44.

[0055] For example, a sensor (not shown) may be provided that directly or indirectly detects the positions of the tooth tips of the pinion gears 32, 42, and control may be performed to shift the rotation start positions of the first motor 10 and the second motor 20 before they start rotating. Also, similar control may be performed while the first motor 10 and the second motor 20 are rotating so that the pinion gears 32, 42 are not simultaneously positioned at the same angle on the circumference. By performing control in this manner, it is possible to shift the rotational phase of the pinion gear 32 relative to the ring gear 34 and the rotational phase of the pinion gear 42 relative to the ring gear 44.

[0056] REFERENCE SIGNS LIST 1 Drive unit (unit) 10 First motor 20 Second motor 30 First planetary gear mechanism 32 Pinion gear (first pinion gear) 34 Ring gear (first ring gear) 34a Internal gear 34b Teeth 34c Tooth space 40 Second planetary gear mechanism 42 Pinion gear (second pinion gear) 44 Ring gear (second ring gear) 44a Internal gear 44b Teeth 44c Tooth space 50 Housing

Claims

1. A unit comprising: a first motor; a second motor; a first planetary gear mechanism connected to the first motor; a second planetary gear mechanism connected to the second motor; and a housing that accommodates the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism, wherein the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism are arranged coaxially, and wherein the rotational phase of a first pinion gear relative to a first ring gear of the first planetary gear mechanism is shifted from the rotational phase of a second pinion gear relative to a second ring gear of the second planetary gear mechanism.

2. A unit comprising: a first motor; a second motor; a first planetary gear mechanism connected to the first motor; a second planetary gear mechanism connected to the second motor; and a housing that accommodates the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism, wherein the first motor, the second motor, the first planetary gear mechanism, and the second planetary gear mechanism are arranged coaxially, and wherein, when viewed from the direction of the rotation axis, the teeth of the internal gear of the first ring gear of the first planetary gear mechanism have portions that overlap with the tooth grooves of the internal gear of the second ring gear of the second planetary gear mechanism.

3. A unit according to claim 2, wherein, when viewed in the direction of the rotation axis, the center of the teeth of the internal gear of the first ring gear has a portion that overlaps with the center of the tooth groove of the internal gear of the second ring gear.

4. A unit according to claim 2 or 3, wherein the circular pitch of the internal gear of said first ring gear is set to be equal to the circular pitch of the internal gear of said second ring gear.

Images