U.S. patent application number 13/979289 was filed with the patent office on 2013-12-05 for motor driving force transmission device.
This patent application is currently assigned to JTEKT CORPORATION. The applicant listed for this patent is Tsune Kobayashi, Keita Nomura, Tohru Onozaki, Hideki Shibata, Kunihiko Suzuki, Masaharu Tagami, Tomoyoshi Takai, Hiroshi Takuno, Motoyasu Yamamori. Invention is credited to Tsune Kobayashi, Keita Nomura, Tohru Onozaki, Hideki Shibata, Kunihiko Suzuki, Masaharu Tagami, Tomoyoshi Takai, Hiroshi Takuno, Motoyasu Yamamori.
Application Number | 20130324342 13/979289 |
Document ID | / |
Family ID | 49098406 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130324342 |
Kind Code |
A1 |
Onozaki; Tohru ; et
al. |
December 5, 2013 |
MOTOR DRIVING FORCE TRANSMISSION DEVICE
Abstract
A motor driving force transmission device includes electric
motors which produce motor driving force with which a rear
differential is operated and a speed reduction and transmission
mechanism which reduces the speed of the motor driving force of the
electric motors and transmits it to the rear differential. The
speed reduction and transmission mechanism has eccentric cams which
rotate as the electric motors are driven, transmission members
which rotate as the eccentric cams rotate, and is disposed on an
outer circumference of the rear differential.
Inventors: |
Onozaki; Tohru; (Nagoya-shi,
JP) ; Kobayashi; Tsune; (Okazaki-shi, JP) ;
Tagami; Masaharu; (Kashihara-shi, JP) ; Yamamori;
Motoyasu; (Nagoya-shi, JP) ; Takuno; Hiroshi;
(Nukata-gun, JP) ; Suzuki; Kunihiko;
(Gamagori-shi, JP) ; Takai; Tomoyoshi;
(Kariya-shi, JP) ; Nomura; Keita; (Kariya-shi,
JP) ; Shibata; Hideki; (Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Onozaki; Tohru
Kobayashi; Tsune
Tagami; Masaharu
Yamamori; Motoyasu
Takuno; Hiroshi
Suzuki; Kunihiko
Takai; Tomoyoshi
Nomura; Keita
Shibata; Hideki |
Nagoya-shi
Okazaki-shi
Kashihara-shi
Nagoya-shi
Nukata-gun
Gamagori-shi
Kariya-shi
Kariya-shi
Kariya-shi |
|
JP
JP
JP
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
JTEKT CORPORATION
Osaka-shi, Osaka
JP
|
Family ID: |
49098406 |
Appl. No.: |
13/979289 |
Filed: |
January 11, 2012 |
PCT Filed: |
January 11, 2012 |
PCT NO: |
PCT/JP2012/050385 |
371 Date: |
August 23, 2013 |
Current U.S.
Class: |
475/150 |
Current CPC
Class: |
F16H 2001/325 20130101;
F16H 48/34 20130101; B60L 2240/423 20130101; B60W 20/00 20130101;
Y02T 10/7072 20130101; B60L 50/61 20190201; B60W 2510/087 20130101;
B60K 6/365 20130101; B60W 2720/406 20130101; Y02T 10/62 20130101;
B60K 17/356 20130101; B60K 7/0007 20130101; B60L 2240/425 20130101;
F16H 48/20 20130101; Y02T 10/64 20130101; B60L 50/16 20190201; F16H
48/08 20130101; B60W 30/1843 20130101; B60W 2710/083 20130101; Y02T
10/72 20130101; B60L 2260/28 20130101; B60W 10/08 20130101; Y02T
10/70 20130101; Y10T 74/19642 20150115; B60L 3/0061 20130101; B60L
2240/36 20130101; B60K 6/52 20130101; B60L 2220/44 20130101; B60K
1/02 20130101; H02K 7/116 20130101; B60L 15/20 20130101 |
Class at
Publication: |
475/150 |
International
Class: |
F16H 48/34 20060101
F16H048/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2011 |
JP |
2011-003349 |
Feb 17, 2011 |
JP |
2011-032206 |
Mar 30, 2011 |
JP |
2011-073852 |
Nov 24, 2011 |
JP |
2011-256577 |
Dec 21, 2011 |
JP |
2011-280033 |
Claims
1. A motor driving force transmission device comprising: an
electric motor which is configured to produce a motor driving force
for operating a differential mechanism; and a speed reduction and
transmission mechanism which is configured to reduce speed of the
motor driving force of the electric motor to transmit to the
differential mechanism, wherein the speed reduction and
transmission mechanism includes: an eccentric cam which is
configured to rotate as the electric motor is driven; and a
transmission member which is configured to rotate as the eccentric
cam rotates, and the speed reduction and transmission mechanism is
disposed on an outer circumference of the differential
mechanism.
2. The motor driving force transmission device according to claim
1, wherein the electric motor is disposed on the outer
circumference of the differential mechanism.
3. The motor driving force transmission device according to claim
1, wherein the electric motor includes: a stator which is fixed to
a device main body; and a rotor which is configured to rotate
around an outer circumference of the stator.
4. The motor driving force transmission device according to claim
1, wherein the electric motor includes: a first electric motor
which is configured to produce a first motor driving force; and a
second electric motor which is connected to the first electric
motor and is configured to produce a second motor driving force,
the first electric motor and the second electric motor being
connected to the differential mechanism via the speed reduction and
transmission mechanism.
5. The motor driving force transmission device according to claim
4, wherein in the speed reduction and transmission mechanism, the
eccentric cam includes a plurality of eccentric cams which are
configured to rotate as at least one of the first electric motor
and the second electric motor is driven, and the transmission
member includes a plurality of transmission members which are
configured to rotate as the plurality of eccentric cams rotate.
6. The motor driving force transmission device according to claim
5, wherein in the speed reduction and transmission mechanism, the
plurality of transmission members are provided on the differential
mechanism at portions which are spaced apart from each other at
equal intervals around a rotational axis of the differential
mechanism.
7. The motor driving force transmission device according to claim
1, wherein in the speed reduction and transmission mechanism, the
plurality of transmission members include internal gears which are
configured to mesh with an input member of the differential
mechanism via external gears.
8. The motor driving force transmission device according to claim
1, wherein in the speed reduction and transmission mechanism, the
plurality of eccentric cams are disposed around an outer
circumference of a portion of an outer circumferential portion of
the input member of the differential mechanism, the portion having
an outside diameter smaller than a largest outside diameter of the
differential mechanism.
9. The motor driving force transmission device according to claim
8, wherein in the speed reduction and transmission mechanism, the
plurality of eccentric cams are: a first eccentric cam which is
positioned on one axial side of an axial central portion of the
input member; and a second eccentric cam which is positioned on the
other axial side of the axial central portion of the input member,
the first eccentric cam and the second eccentric cam being disposed
in line in an axial direction of the input member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a motor driving force
transmission device which is preferably used in an electric vehicle
having, for example, an electric motor as a drive source.
BACKGROUND ART
[0002] In conventional motor driving force transmission devices,
there are driving force transmission devices that include an
electric motor which produces a motor driving force and a speed
reduction and transmission mechanism for transmitting the motor
driving force of the electric motor to a differential mechanism,
which are installed in a motor vehicle (refer to Patent Literature
1, for example).
[0003] The electric motor has an output shaft that rotates based on
electric power of an onboard battery and which is disposed on an
axis of the speed reduction and transmission mechanism.
[0004] The speed reduction and transmission mechanism has a pair of
speed reduction and transmission portions on the periphery of its
axis and is disposed sideways of the differential mechanism, being
connected to the electric motor and the differential mechanism (a
differential case). One of the speed reduction and transmission
portions is connected to the output shaft of the electric motor,
and the other is connected to the differential case side.
[0005] In this configuration, the output shaft of the electric
motor rotates based on the electric power of the onboard battery,
and in association with the rotation of the electric motor, the
motor driving force is transmitted from the electric motor to the
differential mechanism via the speed reduction and transmission
mechanism. Then, the motor driving force transmitted to the
differential mechanism is delivered to left and right wheels from
the differential mechanism.
PRIOR ART LITERATURE
Patent Literature
[0006] Patent Literature 1: JP-A-2007-218407
SUMMARY OF THE INVENTION
Problem that the Invention is to Solve
[0007] According to the motor driving force transmission device
described in Patent Literature 1, however, the speed reduction and
transmission mechanism is disposed on the axis which is parallel to
the axis of the differential mechanism. As a result of this, a
radial dimension of the whole device is increased, leading to a
problem that the whole device is increased in size.
[0008] Consequently, an object of the invention is to provide a
motor driving force transmission device which can reduce the radial
dimension of the whole of the device to thereby realize a reduction
in size in the radial direction of the device.
Means for Solving the Problem
[0009] With a view to attaining the object, the invention provides
a motor driving force transmission device which will be described
under (1) to (9).
(1) There is provided a motor driving force transmission device
comprising an electric motor which generates a motor driving force
for operating a differential mechanism and a speed reduction and
transmission mechanism which is configured to reduce speed of the
motor driving force of the electric motor to transmit to the
differential mechanism, wherein the speed reduction and
transmission mechanism includes an eccentric cam which is
configured to rotate as the electric motor is driven and a
transmission member which is configured to rotate as the eccentric
cam rotates, and the speed reduction and transmission mechanism is
disposed on an outer circumference of the differential mechanism.
(2) In the motor driving force transmission device according to (1)
above, the electric motor is disposed on the outer circumference of
the differential mechanism. (3) In the motor driving force
transmission device according to (1) or (2) above, the electric
motor includes a stator which is fixed to a device main body and a
rotor which is configured to rotate around an outer circumference
of the stator. (4) In the motor driving force transmission device
according to any of (1) to (3) above, the electric motor includes a
first electric motor which is configured to produce a first motor
driving force and a second electric motor which is connected to the
first electric motor and is configured to produce a second motor
driving force, the first electric motor and the second electric
motor being connected to the differential mechanism via the speed
reduction and transmission mechanism. (5) In the motor driving
force transmission device according to (4) above, in the speed
reduction and transmission mechanism, the eccentric cam includes a
plurality of eccentric cams which are configured to rotate as at
least one of the first electric motor and the second electric motor
is driven, and the transmission member includes a plurality of
transmission members which are configured to rotate as the
plurality of eccentric cams rotate. (6) In the motor driving force
transmission device according to (5) above, in the speed reduction
and transmission mechanism, the plurality of transmission members
are provided on the differential mechanism at portions which are
spaced apart from each other at equal intervals around a rotational
axis of the differential mechanism. (7) In the motor driving force
transmission device according to any of (1) to (6) above, in the
speed reduction and transmission mechanism, the plurality of
transmission member includes internal gears which are configured to
mesh with an input member of the differential mechanism via
external gears. (8) In the motor driving force transmission device
according to any of (1) to (7) above, in the speed reduction and
transmission mechanism, the plurality of eccentric cams are
disposed around an outer circumference of a portion of an outer
circumferential portion of the input member of the differential
mechanism, the portion having an outside diameter smaller than a
largest outside diameter of the differential mechanism. (9) In the
motor driving force transmission device according to (8) above, in
the speed reduction and transmission mechanism, the plurality of
eccentric cams are a first eccentric cam which is positioned on one
axial side of an axial central portion of the input member and a
second eccentric cam which is positioned on the other axial side of
the axial central portion of the input member, the first eccentric
cam and the second eccentric cam being disposed in line in an axial
direction of the input member.
Advantage of the Invention
[0010] According to the invention, it is possible to reduce a
radial dimension of the device main body, and hence, it is possible
to realize a reduction in size of the device in a radial
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a plan view shown to schematically illustrate a
vehicle in which a motor driving force transmission device
according to a first embodiment of the invention is installed.
[0012] FIG. 2 is a sectional view shown to illustrate the motor
driving force transmission device according to the first embodiment
of the invention.
[0013] FIG. 3 is a sectional view (a sectional view taken along the
line A-A in FIG. 2) showing a speed reduction and transmission
mechanism of the motor driving force transmission device according
to the first embodiment of the invention.
[0014] FIG. 4 is a sectional view showing an operating state of the
speed reduction and transmission mechanism of the motor driving
force transmission device according to the first embodiment of the
invention.
[0015] FIG. 5 is a sectional view shown to illustrate an electric
motor of the motor driving force transmission device according to
the first embodiment of the invention.
[0016] FIG. 6 is a block diagram shown to illustrate the motor
driving force transmission device according to the first embodiment
of the invention.
[0017] FIG. 7 is a sectional view showing a speed reduction and
transmission mechanism of a motor driving force transmission device
according to a second embodiment of the invention.
[0018] FIG. 8 is a sectional view showing an operating state of the
speed reduction and transmission mechanism of the motor driving
force transmission device according to the second embodiment.
[0019] FIG. 9 is a sectional view shown to illustrate a motor
driving force transmission device according to a third embodiment
of the invention.
[0020] FIG. 10 is a sectional view shown to illustrate a motor
driving force transmission device according to a fourth embodiment
of the invention.
MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0021] Hereinafter, a motor driving force transmission device
according to a first embodiment of the invention will be described
in detail by reference to the drawings.
[0022] FIG. 1 shows schematically a four-wheel-drive vehicle. As
shown in FIG. 1, a four-wheel-drive vehicle 101 employs a front
drive line system related with front wheels which employs an engine
as a drive source and a rear drive line system related with rear
wheels which employs an electric motor as a drive source and
includes a motor driving force transmission device 1, an engine
102, a transaxle 103, a pair of front wheels 104, and a pair of
rear wheels 105.
[0023] The motor driving force transmission device 1 is disposed in
the rear drive line system of the four-wheel-drive vehicle 101 and
is supported together with a rear differential 107 on a vehicle
body (not shown) of the four-wheel-drive vehicle 101 via a
differential carrier (a device main body) 106.
[0024] Additionally, the motor driving force transmission device 1
is designed to transmit a motor driving force of an electric motor
(which will be described later) to the pair of rear wheels 105.
This configuration enables the motor driving force of the electric
motor to be outputted to rear axle shafts 108 via the motor driving
force transmission device 1 and the rear differential 107, whereby
the pair of rear wheels 105 are driven. The motor driving force
transmission device 1 will be described in detail later.
[0025] The engine 102 is disposed in the front drive line system of
the four-wheel-drive vehicle 101. This configuration allows a
driving force of the engine 102 to be outputted to front axle
shafts 109 via the transaxle 103, whereby the pair of front wheels
104 are driven.
[0026] (Overall Configuration of Motor Driving Force Transmission
Device 1)
[0027] FIG. 2 shows the whole of the motor driving force
transmission device. As shown in FIG. 2, the motor driving force
transmission device 1 substantially includes a speed reduction and
transmission mechanism 2 which reduces the speed of at least one
motor driving force of a first motor driving force a and a second
motor driving force b (both of which are shown in FIG. 6) and
transmits it to the rear differential 107, a first electric motor 3
which produces the first motor driving force a, a second electric
motor 4 which produces the second motor driving force b, and a
vehicle ECU (Electronic Control Unit) 5 which functions as a
control unit for outputting control signals which control the first
electric motor 3 and the second electric motor 4.
[0028] The rear differential 107 is made up of a differential
mechanism of a bevel gear type having a differential case (an input
member) 110, a pinion gear shaft 111, a pair of pinion gears 112
and a pair of side gears 113 and is accommodated within the
differential carrier 106.
[0029] By adopting this configuration, a rotational force of the
differential case 110 is delivered from the pinion gear shaft 111
to the side gears 113 via the pinion gears 112 and is further
transmitted to the left and right rear wheels 105 from the rear
axle shafts 108.
[0030] On the other hand, when a driving resistance is produced
between the left and right rear wheels 105, the rotational force of
the differential case 110 is delivered to the left and right rear
wheels 105 in a differential fashion as a result of spinning or
rotating of the pinion gears 112.
[0031] The differential case 110 has an accommodating space 110a
and shaft insertion holes 110b in an interior thereof and is
disposed rotatably within the differential carrier 106 via tapered
roller bearings 114. Additionally, the differential case 110 is
designed to rotate around a rotational axis O when receiving at
least one motor driving force of the first motor driving force a
and the second motor driving force b. An external gear 110c is
mounted on the differential case 110, which has an involute tooth
profile and employs the rotational axis O as a gear axis
thereof.
[0032] The pinion gear shaft 111 is disposed on an axis L which
intersects the rotational axis O at right angles within the
accommodating space 110a in the differential case 110 and is
restricted from rotating around the axis L.
[0033] The pair of pinion gears 112 are supported rotatably on the
pinion gear shaft 111 and are accommodated in the accommodating
space 110a in the differential case 110.
[0034] The pair of side gears 113 are accommodated within the
accommodating space 110a in the differential case 110 and are
connected to the rear axle shafts 108 which pass through the shaft
insertion holes 110b through spline fitting. Additionally, the pair
of side gears 113 are disposed so that their gear axes intersect
gear axes of the pair of pinion gears 112 at right angles so as to
mesh with the pair of pinion gears 112.
[0035] (Configuration of Speed Reduction and Transmission Mechanism
2)
[0036] FIGS. 3 and 4 show the speed reduction and transmission
mechanism. As shown in FIGS. 3 and 4, the speed reduction and
transmission mechanism 2 has a pair of eccentric cams 6,7 which
rotate as at least one electric motor of the first electric motor 3
and the second electric motor 4 (both of which are shown in FIG. 2)
is driven and a pair of transmission members 8, 9 which oscillate
as the pair of eccentric cams 6, 7 rotate and is disposed on an
outer circumference of the rear differential 107 while being
interposed between the first electric motor 3 and the second
electric motor 4 on the rotational axis O (shown in FIG. 2).
[0037] The pair of eccentric cams 6, 7 are disposed in line on the
rotational axis O and are mounted on an inner circumferential
surface of a second connecting member (a connecting cylinder)
10.
[0038] The eccentric cam 6, which is one of the pair of eccentric
cams, has a through hole 6a which is centered at a point (an axis)
O1 which deviates a deviation amount .delta.1 (.delta.1=.delta.)
from a center (a point on the rotational axis O) thereof, and is
disposed to face the first electric motor 3. The eccentric cam 6 is
designed to cause the transmission member 8 to perform a circular
motion which deviates a deviation amount 6 from the rotational
center O when receiving at least one motor driving force of the
first motor driving force a and the second motor driving force b.
When the eccentric cam 6 rotates in one circumferential direction
(a direction indicated by an arrow m1), the transmission member 8
oscillates so that the axis O1 thereof moves in a direction
indicated by an arrow n1 about the rotational axis O. When the
eccentric cam 6 rotates in the other circumferential direction (a
direction indicated by an arrow m2), the transmission member 8
oscillates so that the axis O1 thereof moves in a direction
indicated by an arrow n2 (an opposite direction to the direction
indicated by the arrow n1) about the rotational axis O. The
transmission member 8 moves the axis O1 along a circumferential
direction of a circle that is centered at the rotational axis O and
which has a radius equal to the deviation amount .delta. and
revolves without rotating one full rotation relative to the
differential carrier (the device main body) 106.
[0039] The other eccentric cam 7 has a through hole 7a which is
centered at a point (an axis) O2 which deviates a deviation amount
.delta.2 (.delta.2=.delta.) from a center (a point on the
rotational axis O) thereof, and is disposed to face the second
electric motor 4. The other eccentric cam 7 is designed to cause
the transmission member 9 to perform a circular motion which
deviates the deviation amount .delta. from the rotational center O
when receiving at least one motor driving force of the first motor
driving force a and the second motor driving force b. When the
eccentric cam 7 rotates in the one circumferential direction (the
direction indicated by the arrow m1), the transmission member 9
oscillates so that the axis O2 thereof moves in the direction
indicated by the arrow n1 about the rotational axis O. When the
eccentric cam 7 rotates in the other circumferential direction (the
direction indicated by the arrow m2), the transmission member 9
oscillates so that the axis O2 thereof moves in the direction
indicated by the arrow n2 (the opposite direction to the direction
indicated by the arrow n1) about the rotational axis O. The
transmission member 9 moves the axis O2 along a circumferential
direction of a circle that is centered at the rotational axis O and
which has a radius equal to the deviation amount .delta. and
revolves without rotating one full rotation relative to the
differential carrier (the device main body) 106.
[0040] The one eccentric cam 6 and the other eccentric cam 7 are
mounted on the inner circumferential surface of the second
connecting member (the connecting tube) 10 so that a distance from
the center point O1 of the through hole 6a to the rotational axis O
and a distance from the center point O2 of the through hole 7a to
the rotational axis O are equal and that circumferential distances
of the point O1 and the point O2 around the rotational axis O are
equal.
[0041] The pair of transmission members 8, 9 are made up of
internal gears which mesh with the external gear 110c of the
differential case 110, are disposed along the rotational axis O and
are provided on the external gear 110c at portions which are spaced
apart from each other at equal intervals (180.degree.) around the
rotational axis (the rotational axis O) of the external gear 110c.
By adopting this configuration, the speed reduction and
transmission mechanism 2 is connected to the rear differential 107
in a well-balanced fashion. Internal gears having an involute tooth
profile are employed for the pair of transmission members 8, 9
which have a larger number of teeth Z2 (for example, Z2=211) than
the number of teeth Z1 (for example, Z1=198) of the external gear
110c and which are in mesh with the external gears 110c having the
involute tooth profile at all times. A speed reduction ratio of the
speed reduction and transmission mechanism 2 is calculated by
diving (Z2-Z1) by Z2 or (Z2-Z1)/Z2.
[0042] The transmission member 8, which is one of the pair of
transmission members, is disposed rotatably on an inner surface of
the through hole 6a in the eccentric cam 6, which is one of the
pair of eccentric cams, via a needle roller bearing 12. A plurality
of pin insertion holes 8a are disposed in the transmission member 8
at equal intervals in a circumferential direction thereof so that a
plurality of first connecting members (connecting pins) 11 are
inserted therethrough, each pin insertion hole 8a having a bore
diameter which is larger than a dimension resulting from adding the
deviation amount 6 to a pin diameter of each connecting pin 11.
[0043] The transmission member 9, which is the other of the pair of
transmission members, is disposed rotatably on an inner surface of
the through hole 7a in the eccentric cam 7, which is the other of
the pair of eccentric cams, via a needle roller bearing 12.
Similarly to the transmission member 8, a plurality of pin
insertion holes 9a are disposed in the other transmission member 9
at equal intervals in a circumferential direction thereof so that
the plurality of connecting pins 11 are inserted therethrough, each
pin insertion hole 9a having a bore diameter which is larger than
the dimension resulting from adding the deviation amount b to the
pin diameter of each connecting pin 11.
[0044] (Configuration of First Electric Motor 3)
[0045] FIG. 5 shows the electric motor. FIG. 6 shows a control
system of the speed reduction and transmission mechanism. As shown
in FIGS. 5 and 6, the first electric motor 3 has a stator 3a and a
rotor 3b and is connected to the rear differential 107 via the
speed reduction and transmission mechanism 2 on the rotational axis
O (shown in FIG. 2), and the stator 3a is connected to the ECU 5.
Additionally, the first electric motor 3 is configured so that when
a control signal is inputted thereinto from the ECU 5, the stator
3a produces the first motor driving force a for operating the rear
differential 107 between the rotor 3b and itself so as to rotate
the rotor 3b.
[0046] The stator 3a has a stator core 30a and coils 31a, is
disposed on an inner circumferential side of the first electric
motor 3 and is fixed to the differential carrier 106 (shown in FIG.
2).
[0047] The stator core 30a includes, for example, a plurality of
silicon steel plates which are laminated one on the top of the
other and is made up of a cylindrical member as a whole. A
plurality of (20 in this embodiment) tees 300a are provided side by
side in a circumferential direction at equal intervals on an outer
circumferential surface of the stator core 30a.
[0048] The coil 31a is made up of an electric wire which is
supplied with electric power from an onboard battery (not shown)
and is wound around the tee 300a of the stator core 30a.
[0049] The rotor 3b has a rotor core 30b and segment magnets 31b
and is disposed on an outer circumferential side of the first
electric motor 3.
[0050] The rotor core 30b includes, for example, a plurality of
silicon steel plates which are laminated one on the top of the
other and is made up of a cylindrical member as a whole.
[0051] The segment magnets 31b include a plurality of (four in this
embodiment) permanent magnets which are magnetized to an N pole and
an S pole from a rotor radial inner side towards a rotor radial
outer side and a plurality of (four in this embodiment) permanent
magnets which are magnetized to an N pole and an S pole from a
rotor radial outer side towards a rotor radial inner side. These
permanent magnets of the two types are aligned alternately side by
side in the circumferential direction and are bonded to an inner
circumferential surface of the rotor core 30b at equal
intervals.
[0052] (Configuration of Second Electric Motor 4)
[0053] The second electric motor 4 has a stator 4a and a rotor 4b
and is connected to the rear differential 107 via the speed
reduction and transmission mechanism 2 on the rotational axis O
(shown in FIG. 2), and the stator 4a is connected to the ECU 5.
Additionally, the second electric motor 4 is configured so that
when a control signal is inputted thereinto from the ECU 5, the
stator 4a produces the second motor driving force b for operating
the rear differential 107 between the rotor 4b and itself so as to
rotate the rotor 4b.
[0054] The stator 4a has a stator core 40a and coils 41a, is
disposed on an inner circumferential side of the second electric
motor 4 and is fixed to the differential carrier 106. In addition,
the stator 4a is connected to the stator 3a of the first electric
motor 3 via a plurality of connecting pins 11. The stator 4a is
mounted together with the stator 3a on the differential carrier 106
(shown in FIG. 2) with nuts 13 (shown in FIG. 2).
[0055] The stator core 40a includes, for example, a plurality of
silicon steel plates which are laminated one on the top of the
other and is made up of a cylindrical member as a whole. A
plurality of (20 in this embodiment) tees 400a are provided side by
side in a circumferential direction at equal intervals on an outer
circumferential surface of the stator core 40a.
[0056] The coil 41a is made up of an electric wire which is
supplied with electric power from the onboard battery (not shown)
and is wound around the tee 400a of the stator core 40a.
[0057] The rotor 4b has a rotor core 40b and segment magnets 41b,
is disposed on an outer circumferential side of the second electric
motor 4, and is connected to the rotor 3b of the first electric
motor 3 via a connecting cylinder 10.
[0058] The rotor core 40b includes, for example, a plurality of
silicon steel plates which are laminated one on the top of the
other and is made up of a cylindrical member as a whole.
[0059] The segment magnets 41b include a plurality of (four in this
embodiment) permanent magnets which are magnetized to an N pole and
an S pole from a rotor radial inner side towards a rotor radial
outer side and a plurality of (four in this embodiment) permanent
magnets which are magnetized to an N pole and an S pole from a
rotor radial outer side towards a rotor radial inner side. These
permanent magnets of the two types are aligned alternately side by
side in the circumferential direction and are bonded to an inner
circumferential surface of the rotor core 40b at equal
intervals.
[0060] (Configuration of ECU 5)
[0061] The ECU 5 is connected to a sensor (not shown) in addition
to the first electric motor 3 and the second electric motor 4.
Additionally, when a detection signal is inputted thereinto which
signals that a driving torque which is smaller than a predetermined
torque is required for the rear differential 107, the ECU 5 outputs
a control signal to drive alternately the first electric motor 3
and the second electric motor 4, while the detection signal signals
that a driving torque which is equal to or larger than the
predetermined torque is required for the rear differential 107, the
ECU 5 outputs a control signal to drive both the first electric
motor 3 and the second electric motor 4.
[0062] By adopting this configuration, the ECU 5 puts the
four-wheel-drive vehicle 101 in a four-wheel-drive state based on
the front drive line system and the rear drive line system by not
only operating the rear drive line system by driving at least one
electric motor of the first electric motor 3 and the second
electric motor 4 but also driving the front wheels 104 by the
engine 102.
[0063] In addition, while the four-wheel-drive vehicle 101 is
running normally, the ECU 5 puts the four-wheel-drive vehicle 101
in a two-wheel-drive state by stopping the operation of the rear
drive line system by stopping the driving of the first electric
motor 3 and the second electric motor 4 while allowing the engine
102 to drive the front wheels 104.
[0064] (Operation of Motor Driving Force Transmission Device 1)
[0065] Next, the operation of the motor driving force transmission
device 1 illustrated in this embodiment will be described by using
FIGS. 1 to 4 and 6.
[0066] In FIG. 2, when, by supplying electric power to one electric
motor of the first electric motor 3 and the second electric motor 4
(for example, the first electric motor 3) of the four-wheel-drive
vehicle 101 (shown in FIG. 1), the first electric motor 3 is
driven, the first motor driving force a (shown in FIG. 6) of this
first electric motor 3 is imparted to the speed reduction and
transmission mechanism 2 via the connecting cylinder 10, whereby
the speed reduction and transmission mechanism 2 is actuated.
[0067] Because of this, in the speed reduction and transmission
mechanism 2, as shown in FIGS. 3 and 4, the eccentric cams 6, 7
rotate, for example, in the direction indicated by the arrow m1,
and the transmission members 8, 9 perform circular motions in the
direction indicated by the arrow n1 while sliding on each other
with the transmission members 8, 9 each deviating the deviation
amount .delta. from the rotation axis O.
[0068] In conjunction with this, the first motor driving force a is
transmitted from the transmission members 8, 9 to the external gear
110c of the rear differential 107 (shown in FIG. 1), whereby the
external gear 110c rotates in the opposite direction (the direction
indicated by the arrow m2) to the rotating direction of the
eccentric cams 6, 7.
[0069] This actuates the rear differential 107, and the first motor
driving force a is delivered to the rear axle shafts 108 to thereby
be transmitted to the left and right rear wheels 105.
[0070] Here, to allow the motor driving force transmission device 1
to continue to operate when the driving torque which is smaller
than the predetermined torque is required for the rear differential
107, when a predetermined period of time during which the first
electric motor 3 is to be driven continuously elapses, the supply
of electric power to the first driving motor 3 is stopped, and the
second electric motor 4, which is the other electric motor, is
driven. This is because the first electric motor 3 is heated
excessively in case the supply of electric power to the first
electric motor 3 still continues even after the predetermined
period of time elapses. Thus, the first electric motor 3 is
prevented from being heated excessively by stopping the supply of
electric power to the first electric motor 3.
[0071] Then, when the second electric motor 4 is driven by supply
electric power to the second electric motor 4, the second motor
driving force b (shown in FIG. 6a) of the second electric motor 4
is imparted to the speed reduction and transmission mechanism 2 via
the connecting cylinder 10, whereby the speed reduction and
transmission mechanism 2 is actuated. Because of this, in a similar
way to the way in which the first electric motor 3 is driven, the
second motor driving force b is transmitted to the rear
differential 107 via the speed reduction and transmission mechanism
2. This actuates the rear differential 107, and the second motor
driving force b is delivered to the rear axle shafts 108 to thereby
be transmitted to the left and right rear wheels 105.
[0072] Here, to allow the motor driving force transmission device 1
to continue to operate when the driving torque which is smaller
than the predetermined torque is required for the rear differential
107, when a predetermined period of time during which the second
electric motor 4 is to be driven continuously elapses, the supply
of electric power to the second driving motor 4 is stopped, and the
first electric motor 3 is driven.
[0073] In this way, the first electric motor 3 and the second
electric motor 4 are driven alternately to thereby restrain the
first electric motor 3 and the second electric motor 4 from being
heated excessively, thereby making it possible to allow the motor
driving force transmission device 1 to operate continuously.
[0074] In the motor driving force transmission device 1 configured
in the way described heretofore, since the speed reduction and
transmission mechanism 2, the first electric motor 3 and the second
electric motor 4 are disposed on the outer circumference of the
rear differential 107, it is possible to reduce the axial and
radial dimensions of the motor driving force transmission device
1.
[0075] In this embodiment, since the rotation of the first electric
motor 3 and the second electric motor 4 is transmitted to the rear
wheels 105 while being reduced in speed by the speed reduction and
transmission mechanism 2, even in the event that low torque
electric motors are used as the first electric motor 3 and the
second electric motor 4, it is possible to transmit a relatively
large torque to the rear wheels 105. As this occurs, since the
rotor 3b and the rotor 4b are disposed on the outer circumference
of the stator 3a and the stator 4a, respectively, it is possible to
transmit a larger torque to the rear wheels 105 than when the
rotors are disposed on an inner circumference of the stators.
[0076] Additionally, in this embodiment, since the segment magnets
31b of the rotor 3b are bonded to the inner circumferential surface
of the rotor core 30b and the segment magnets 41b of the rotor 4b
are bonded to the inner circumferential surface of the rotor core
40b, there is no such situation that a force is applied to the
segment magnets 31, 41b that is produced as a result of a
centrifugal force being produced by the rotation of the rotors 3b,
4b and which attempts to separate the segment magnets 31b, 41b from
the corresponding rotor cores 30b, 40b.
[0077] In the embodiment, while the motor driving force
transmission device 1 is described as being actuated by rotating
the eccentric cams 6, 7 in the direction indicated by the arrow m1,
the motor driving force transmission device 1 can also be actuated
in a similar way to the way described in this embodiment even by
rotating the eccentric cams 6, 7 in the direction indicated by the
arrow m2. As this occurs, the external gear 110c rotates in the
opposite direction (the direction indicated by the arrow m1) to the
rotating direction of the eccentric cams 6, 7.
[0078] In addition, while the first motor driving force a or the
second motor driving force b is described as being transmitted from
the speed reduction and transmission mechanism 2 to the rear
differential 107, the invention is not limited thereto. When the
torque which is equal to or larger than the predetermined torque is
required for the rear differential 107, it is possible to transmit
a motor driving force which is larger than the first motor driving
force a and the second motor driving force b from the speed
reduction and transmission mechanism 2 to the rear differential 107
by driving both the first electric motor 3 and the second electric
motor 4.
[0079] [Advantage of First Embodiment]
[0080] According to the first embodiment that has been described
heretofore, the following advantages can be obtained.
(1) The speed reduction and transmission mechanism 2, the first
electric motor 3 and the second electric motor 4 are disposed on
the outer circumference of the rear differential 107, whereby the
axial and radial dimensions of the motor driving force transmission
device 1 (the device main body) can be reduced, thereby making it
possible to realize a reduction in size of the device as a whole.
(2) Since the rotor 3b of the first electric motor 3 is disposed on
the outer circumference of the stator 3a thereof and the rotor 4b
of the second electric motor 4 is disposed on the outer
circumference of the stator 4a thereof, it is possible to produce a
larger motor driving force than when the rotors are disposed on the
inner circumference of the stators. (3) The motor driving force
transmission device 1 can be used continuously by employing
alternately the first electric motor 3 and the second electric
motor 4, whereby the first electric motor 3 and the second electric
motor 4 are restrained from generating heat excessively even when
the motor driving force transmission device 1 is operated
continuously over a long period of time.
Second Embodiment
[0081] Next, a motor driving force transmission device according to
a second embodiment of the invention will be described by using
FIGS. 7 and 8. FIGS. 7 and 8 show a speed reduction and
transmission mechanism. In FIGS. 7 and 8, like reference numerals
will be given to members which have the same or similar functions
to those shown in FIGS. 3 and 4, and the detailed description
thereof will be omitted here.
[0082] As shown in FIGS. 7 and 8, a speed reduction and
transmission mechanism 71 of a motor driving force transmission
device according to the second embodiment of the invention is
characterized in that a pair of transmission members 72, 73 are
formed of internal gears having a cycloid tooth profile.
[0083] Because of this, an external gear 110c of a differential
case 110 of a rear differential 107 is formed of an external gear
having a cycloid tooth profile that has a smaller number of teeth
than those of the pair of transmission members 72, 73 and which is
normally in mesh with the pair of transmission members 72, 73.
[0084] Additionally, the pair of transmission members 72, 73 are
disposed along a rotational axis O (shown in FIG. 2) and are
connected to the external gear 110c at portions which are spaced
180.degree. apart from each other around the rotational axis (the
rotational axis O) thereof.
[0085] In the motor driving force transmission device configured in
the way described above, similar to the motor driving force
transmission device 1 described in the first embodiment, the speed
reduction and transmission mechanism 2, a first electric motor 3
and a second electric motor 4 are disposed on an outer
circumference of the rear differential 107, and therefore, it is
possible to reduce an axial and radial dimensions of the motor
driving force transmission device 1.
[0086] [Advantage of the Second Embodiment]
[0087] According to the second embodiment that has been described
above, a similar advantage to the advantage of the first embodiment
can be obtained.
Third Embodiment
[0088] Next, a motor driving force transmission device according to
a third embodiment of the invention will be described by using FIG.
9. FIG. 9 shows a motor driving force transmission device. In FIG.
9, like reference numerals will be given to members which have the
same or like functions to those shown in FIG. 2, and the detailed
description thereof will be omitted here.
[0089] As shown in FIG. 9, a motor driving force transmission
device 80 according to the third embodiment of the invention is
characterized by including a housing 81 of which a rotational axis
O is an axis of rear axle shafts 108, a rear differential 107 which
delivers a motor driving force to rear wheels 105, an electric
motor 82 which generates a motor driving force for operating the
rear differential 107 and a speed reduction and transmission
mechanism 2 which reduces the speed of the driving force of the
electric motor 82 to transmit it to the rear differential 107, with
the speed reduction and transmission mechanism 2 disposed on the
same axis as an axis of the electric motor 82 (the rotational axis
O).
[0090] It should be noted that since the electric motor 82 is
substantially the same in configuration as the first electric motor
3 and the second electric motor 4 which are described in the first
embodiment, corresponding reference numerals will be given to
portions corresponding to the portions of, for example, the first
electric motor 3 (reference numerals 82a and 82b will be given to a
stator of the electric motor 82 and a rotor of the electric motor
82, respectively, so as to correspond to the stator 3a and the
rotor 3b of the first electric motor 3).
[0091] In addition, one side end portion and the other side end
portion of a differential case 110 is supported rotatably on a
bearing mounting portion 810b of a first housing element 810 via a
ball bearing 86 and on a bearing mounting portion 830b of a stator
supporting member 83 via a ball bearing 87, respectively.
[0092] The housing 81 has the first housing element 810 which
accommodates the rear differential 107 and the speed reduction and
transmission mechanism 2 and a second housing element 811 that
communicates with the first housing element 810 and accommodates
the electric motor 82 (except some parts) and which is disposed on
a vehicle body.
[0093] The first housing element 810 is disposed at one side of the
housing 81 and is formed of a stepped and bottomed cylindrical
member which is opened in a side which faces the second housing
element 811 as a whole. A shaft insertion hole 810a is provided in
a bottom portion of the first housing element 810, allowing the
rear axle shaft 108 to be inserted therethrough.
[0094] A cover 115 which covers an opening portion in the shaft
insertion hole 810a is interposed between one of the rear wheels
105 and the shaft insertion hole 810a. The cover 115 has a
cylindrical portion 115a through which the rear axle shaft 108 is
inserted, and an inner circumferential surface of the cylindrical
portion 115a is attached to an outer circumferential surface of the
rear axle shaft 108. A seal member 116 which seals up the opening
portion in the shaft insertion hole 810a is attached to an inner
circumferential surface of the shaft insertion hole 810a. In
addition, a differential case bearing mounting portion 810b is
provided on the inner circumferential surface of the shaft
insertion hole 810a.
[0095] An attaching flange 810c is provided integrally at an
opening end portion of the first housing element 810 so as to
project from an outer circumferential surface thereof. A plurality
of (six in this embodiment) pin mounting holes 810d are arranged at
equal intervals around the rotational axis O in the first housing
element 810 so that connecting pins 11 are mounted therein.
[0096] The second housing element 811 is disposed at the other side
of the housing 81 and is formed of a bottomed cylindrical member
which is opened in a side which faces the first housing element 810
as a whole. A shaft insertion hole 811a through which the rear axle
shaft 108 is inserted is provided in a bottom portion of the second
housing element 811.
[0097] A cover 117 which covers an opening portion in the shaft
insertion hole 811a is interposed between the other of the rear
wheels 105 and the shaft insertion hole 811a. The cover 117 has a
cylindrical portion 117a through which the rear axle shaft 108 is
inserted, and an inner circumferential surface of the cylindrical
portion 117a is attached to an outer circumferential surface of the
rear axle shaft 108. A seal member 118 which seals up the opening
portion in the shaft insertion hole 811a is attached to an inner
circumferential surface of the shaft insertion hole 811a.
[0098] In addition, a first rising portion 811b and a second rising
portion 811c are provided integrally on a bottom portion of the
second housing element 811 so that the first rising portion 811b
projects therefrom at an inner opening circumferential edge of the
shaft insertion hole 811a and that the second rising portion 811c
projects therefrom in a position lying radially outwards of the
first rising portion 811b. The cylindrical stator supporting
portion 83, which faces oppositely the bottom portion of the second
housing element 811 across the electric motor 82, is attached
together with the stator 82a of the electric motor 82 to the first
rising portion 811b with attaching bolts 84.
[0099] The stator supporting member 83 has a shaft insertion hole
83a through which the rear axle shaft 108 is inserted and is
interposed between the electric motor 82 and the speed reduction
and transmission mechanism 2. A flange 83b is provided integrally
on an outer circumferential surface of the stator supporting member
83 so as to project therefrom. A differential case bearing mounting
portion 830b is provided on an inner circumferential surface of the
flange 83b. A plurality of (six in this embodiment) pin mounting
holes 831b are provided in the flange 83b so that connecting pins
11 are mounted therein.
[0100] A shaft bearing mounting portion 811b and a rotor bearing
mounting portion 8110c are provided on an inner circumferential
surface of the first rising portion 811b and on an outer
circumferential surface of the second rising portion 811c,
respectively.
[0101] The electric motor 82 is made up of an outer rotor motor
which includes the stator 82a and the rotor 82b and is connected to
the rear differential 107 via the speed reduction and transmission
mechanism 2 on the motor axis (the rotational axis O), and the
stator 82a is connected to an ECU 5 (shown in FIGS. 2 and 5). Then,
in the electric motor 82, when a control signal is inputted into
the stator 82a from the ECU 5, a motor driving force which operates
the rear differential 107 is generated between the stator 82a and
the rotor 82b so as to rotate the rotor 82b.
[0102] The stator 82a is disposed on an inner circumferential side
of the electric motor 82 and is attached together with the stator
supporting member 83 to the first rising portion 811b of the second
housing element 811 with the attaching bolts 84.
[0103] The rotor 82b is disposed on an outer circumferential side
of the electric motor 82 and is supported rotatably on a rotor
bearing mounting portion 8110c on the second rising portion 811c
via a bearing 85.
[0104] The speed reduction and transmission mechanism 2 has a pair
of eccentric cams 6, 7 which are driven to rotate by the electric
motor 82 and a pair of transmission members 8, 9 which oscillate in
association with the rotation of the pair of eccentric cams 6, 7
and is disposed on an outer circumference of the rear differential
107 on the same axis as an axis of the electric motor 82 (the
rotational axis O).
[0105] When the eccentric cam 6 rotates in one circumferential
direction (the direction indicated by the arrow m1), the
transmission member 8 oscillates so that an axis O1 thereof moves
in the direction indicated by the arrow n1 about the rotational
axis O. When the eccentric cam 6 rotates in the other
circumferential direction (the direction indicated by the arrow
m2), the transmission member 8 oscillates so that the axis O1
thereof moves in the direction indicated by the arrow n2 (the
opposite direction to the direction indicated by the arrow n1)
about the rotational axis O. The transmission member 8 moves the
axis O1 along a circumferential direction of a circle that is
centered at the rotational axis O and which has a radius equal to a
deviation amount .delta. and revolves without rotating one full
rotation relative to the housing (a device main body) 81.
[0106] When the eccentric cam 7 rotates in the one circumferential
direction (the direction indicated by the arrow m1), the
transmission member 9 oscillates so that an axis O2 thereof moves
in the direction indicated by the arrow n1 about the rotational
axis O. When the eccentric cam 7 rotates in the other
circumferential direction (the direction indicated by the arrow
m2), the transmission member 9 oscillates so that the axis O2
thereof moves in the direction indicated by the arrow n2 (the
opposite direction to the direction indicated by the arrow n1)
about the rotational axis O. The transmission member 9 moves the
axis O2 along a circumferential direction of a circle that is
centered at the rotational axis O and which has a radius equal to a
deviation amount .delta. and revolves without rotating one full
rotation relative to the housing (the device main body) 81.
[0107] In the motor driving force transmission device 80 which is
configured in this way, when the electric motor 82 is driven by
supplying electric power to the electric motor 82, the motor
driving force of the electric motor 82 is imparted to the speed
reduction and transmission mechanism 2 via a connecting cylinder
10, whereby the speed reduction and transmission mechanism 2
operates in a similar way to the way in which the motor driving
force transmission device 1 described in the first embodiment
operates.
[0108] [Advantage of the Third Embodiment]
[0109] According to the third embodiment that has been described
heretofore, the following advantages will be obtained.
(1) The radial dimension of the motor driving force transmission
device 1 (the device main body) can be reduced by disposing the
speed reduction and transmission mechanism 2 on the outer
circumference of the electric motor 8, thereby making it possible
to realize a reduction in size of the device in the radial
direction thereof. (2) Since the rotor 82b is disposed on the outer
circumference of the stator 82a of the electric motor 82, when
compared with a case where the rotor is disposed on an inner
circumference of the stator, a larger motor driving force can be
produced.
Fourth Embodiment
[0110] Next, a motor driving force transmission device according to
a fourth embodiment will be described by using FIG. 10. FIG. 10
shows a motor driving force transmission device. In FIG. 10, like
reference numerals will be given to members having functions like
or similar to those of the members shown in FIG. 9, and the
detailed description thereof will be omitted here.
[0111] As shown in FIG. 10, a motor driving force transmission
device 90 according to the fourth embodiment of the invention is
characterized in that eccentric cams 6, 7 are disposed on outer
circumferences of portions 110g, 110h which lie on an outer
circumferential portion of a differential case (an input member)
110 of a rear differential 107 and have outside diameters which are
smaller than a largest outside diameter D1 of the differential case
110.
[0112] Because of this, the differential case 110 is formed of a
rotational member which includes the portions 110g, 110h and has a
portion 110d which supports a pinion gear shaft 111 at an axially
central portion thereof, the rotational member additionally having
portions 110e, 110f where ball bearings 86, 87 are mounted at axial
end portions thereof and being formed symmetrical relative to a
rotational axis O and an axis L.
[0113] An outside diameter D1 of the portion 110d is set to a
largest dimension in outside diameters of outer circumferential
portions on the differential case 110.
[0114] The portion 110e is disposed on one axial side of the
portion 110d, and the portion 110f is disposed on the other axial
side of the portion 110d. An outside diameter D2 of the portion
110e is set to a dimension which is smaller than an outside
diameter D3 of the portion 110f (D3>D2). The outside diameter D2
of the portion 110e and the outside diameter D3 of the portion 110f
are both set to the dimensions which are smaller than the outside
diameter D1 of the portion 110d (D1>D3>D2).
[0115] The portions 110g, 110h are disposed in line in the axial
direction (the rotational axis O) of the differential case 110.
Additionally, the portion 110g is interposed between the portion
110d and the portion 110e, and the portion 110h is interposed
between the portion 110d and the portion 110f. Outside diameters of
the portions 110g, 110h are substantially equal (referred to as D4)
and are set to a dimension which is larger than the outside
diameters D2, D3 (D3<D4) but is smaller than the outside
diameter D1 (D1>D3).
[0116] An external gear 110i which meshes with one transmission
member 8 of transmission members is mounted on an outer
circumferential portion of the portion 110g, and an external gear
110j which meshes with the other transmission member 9 is mounted
on an outer circumferential portion of the portion 110h. A gear
that employs the rotational axis O as a gear axis thereof and which
has an involute tooth profile is used for the external gears 110i,
110j.
[0117] Connecting pins 11 are inserted through pin insertion holes
8a in the one transmission member 8, and the transmission member 8
is supported rotatably (so as to perform a circular motion) by the
connecting pins 11 via a needle roller bearing 88. In addition, the
eccentric cam (a first eccentric cam) 6 is disposed rotatably on an
outer circumferential portion of the one transmission member 8 via
a needle roller bearing 12. Additionally, the one transmission
member 8 is restricted from moving in an axial direction towards
the other transmission member 9 by a movement restricting member
98.
[0118] The connecting pins 11 are inserted through pin insertion
holes 9a in the other transmission member 9, and the transmission
member 9 is supported rotatably (so as to perform a circular
motion) by the connecting pins 11 via a needle roller bearing 88.
In addition, the eccentric cam (a second eccentric cam) 7 is
disposed rotatably on an outer circumferential portion of the other
transmission member 9 via a needle roller bearing 12. Additionally,
the other transmission member 9 is restricted from moving in an
axial direction towards the one transmission member 8 by a movement
restricting member 99.
[0119] In the motor driving force transmission device 90 which is
configured in this way, when an electric motor 82 is driven by
supplying electric power to the electric motor 82, the motor
driving force of the electric motor 82 is imparted to a speed
reduction and transmission mechanism 2 via a connecting cylinder
10, whereby the speed reduction and transmission mechanism 2
operates in a similar way to the way in which the motor driving
force transmission device 80 described in the third embodiment
operates.
[0120] [Advantage of the Fourth Embodiment]
[0121] According to the fourth embodiment that has been described
heretofore, the following advantages will be obtained.
(1) The eccentric cams 6, 7 are disposed on the outer
circumferential portion of the differential case 110 at the outer
circumferences of the portions 110g, 110h whose outside diameters
D4 are smaller than the largest outside diameter D1 of the
differential case 110, whereby the radial dimension of the motor
driving force transmission device 90 can be reduced, thereby making
it possible to realize a reduction in size of the device in the
radial direction. In this case, the reduction in size of the device
in the radial direction is enabled by disposing the speed reduction
and transmission mechanism 2 by making use of space portions
(so-called dead spaces) which are situated on both axial sides of
the portion 110d of the differential case 110, and therefore, this
size reduction is attained by avoiding the enlargement of the motor
driving force transmission device 90 in the axial direction. (2)
The ball bearings 86, 87 can be disposed at the portions 110e, 110f
whose outside diameters D2, D3 are smaller than the outside
diameters D4 of the portions 110g, 110h, and therefore, the ball
bearings 86, 87 can be made small in size, thereby making it
possible to realize a reduction in production costs. (3) A rotor
82b is disposed on an outer circumference of a stator 82a of the
electric motor 82, and therefore, similar to the advantage
described in the third embodiment, a larger motor driving force can
be produced than when the rotor is disposed on the inner
circumference of the stator.
[0122] Thus, while the motor driving force transmission device of
the invention has been described based on the embodiments thereof,
the invention is not limited to the embodiments that have been
described, and hence, the invention can be carried out in various
forms without departing from the spirit and scope thereof. For
example, the following modifications are also possible.
(1) In the embodiments (the first embodiment and the second
embodiment), while the first electric motor 3 and the second motor
4 are switched to be driven alternately when the predetermined
period of time elapses, the invention is not limited thereto. The
electric motors may be switched to be driven alternately when the
integral value of the motor current of the first electric motor or
the second electric motor reaches or exceeds a predetermined
threshold. Additionally, the electric motors may be switched to be
driven alternately when the temperature of the first electric motor
or the second electric motor reaches or exceeds a predetermined
threshold or when the rotational speed of the first electric motor
or the second electric motor reaches a predetermined threshold. (2)
In the embodiments, the one eccentric cam 6 and the other eccentric
cam 7 are described as being installed on the inner circumferential
surface of the second connecting member (the connecting cylinder)
10 so that the distance from the center point O1 of the through
hole 6a to the rotation axis O equals the distance from the center
point O2 of the through hole 7a to the rotational axis O and that
the point O1 and the point O2 are spaced equidistantly apart from
each other around the rotational axis O, and the pair of
transmission members 8, 9 (the transmission members 72, 73) are
described as being provided on the rear differential 107 at the
portions which are spaced equidistantly (180.degree.) apart from
each other around the rotational axis. However, the invention is
not limited thereto, and the number of transmission members can be
changed as required. Namely, when the number of transmission
members is n (n.gtoreq.3), assuming that a center point of a
through hole of a first eccentric cam, a center point of a through
hole of a second eccentric cam, . . . and a center point of a
through hole of an nth eccentric cam are disposed sequentially in
one direction around the rotational axis of the second connecting
member on an imaginary plane which intersects the rotational axis
of the second connecting member (the rotational axis of the rear
differential) at right angles, the eccentric cams are installed on
the inner circumferential surface of the second connecting member
so that distances from the center points of the through holes to
the rotational axis equal each other and that an included angle
which is formed by lines which connect the center points of the
through holes of any two adjacent eccentric cams of the first
eccentric cam, the second eccentric cam, . . . and the nth
eccentric cam and the rotational axis of the second connecting
member is 360.degree./n, and the n transmission members are
provided on the rear differential at portions which are spaced
apart from each other at angular intervals of 360.degree./n around
the rotational axis thereof. For example, in the case of three
transmission members being provided, assuming that a center point
of a first eccentric cam, a center point of a through hole of a
second eccentric cam and a center point of a through hole of a
third eccentric cam are disposed sequentially in one direction
around the rotational axis of the second connecting member on the
imaginary plane which intersects the rotational axis of the second
connecting member, the three transmission members are installed on
the inner circumferential surface of the second connecting member
so that distances from the center points of the through holes to
the rotational axis of the second connecting member equal each
other and that an included angle which is formed by lines which
connect the center points of the through holes of any two adjacent
eccentric cams of the first eccentric cam, the second eccentric cam
and the third eccentric cam and the rotational axis of the second
connecting member is 120.degree., and the three transmission
members are provided on the rear differential at portions which are
spaced apart from each other at angular intervals of 120.degree.
around the rotational axis thereof. (3) In the embodiments
described above, while the invention is described as being applied
to the four-wheel-drive vehicle 101 which employs the engine 102
and the electric motors 3, 4 in parallel as the drive source, the
invention is not limited thereto, and hence, the invention can also
be applied to an electric vehicle which employs only an electric
motor as a drive source in a similar way to the way in which the
embodiments are carried out. (4) In the embodiments described
above, while the invention is described as being applied to the
four-wheel-drive vehicle 101 in which the front wheels 104 are
driven by the engine 102 which is mounted at the front and the rear
wheels 105 are driven by the electric motor (the first electric
motor 3 and the second electric motor 4 in the first and second
embodiments and the electric motor 82 in the third and fourth
embodiments) which is mounted at the rear of the vehicle, the
invention is not limited thereto, and hence, the invention can also
be applied to a four-wheel-drive vehicle in which rear wheels are
driven by an engine which is mounted at the front and front wheels
are driven by an electric motor which is mounted at the rear of the
vehicle.
INDUSTRIAL APPLICABILITY
[0123] According to the invention, the radial dimension of the
device main body can be reduced, thereby making it possible to
realize a reduction in size of the device in the radial
direction.
[0124] This patent application is based on Japanese Patent
Application No. 2011-3349 filed on Jan. 11, 2011, Japanese Patent
Application No. 2011-32206 filed on Feb. 17, 2011, Japanese Patent
Application No. 2011-73852 filed on Mar. 30, 2011, Japanese Patent
Application No. 2011-256577 filed on Nov. 24, 2011, and Japanese
Patent Application No. 2011-280033 filed on Dec. 21, 2011, the
contents of which are incorporated herein by reference.
DESCRIPTION OF REFERENCE NUMERALS
[0125] 1 motor driving force transmission device; 2 speed reduction
and transmission mechanism; 3 first electric motor; 3a stator; 30a
stator core; 300a tee; 31a coil; 3b rotor; 30b rotor core; 31b
segment magnet; 4 second electric motor; 4a stator; 40a stator
core; 400a tee; 41a coil; 4b rotor; 40b rotor core; 41b segment
magnet; 5 ECU; 6, 7 eccentric cam; 6a, 7a through hole; 8, 9
transmission member; 8a, 9a pin insertion hole; 10 connecting
cylinder; 11 connecting pin; 12 needle roller bearing; 13 nut; 71
speed reduction and transmission mechanism; 72, 73 transmission
member; 80 motor driving force transmission device; 81 housing; 810
first housing element; 810a shaft insertion hole; 810b bearing
mounting portion; 810c attaching flange; 810d pin mounting hole;
811 second housing element; 811a shaft insertion hole; 811b first
rising portion; 8110b bearing mounting portion; 811c second rising
portion; 8110c bearing mounting portion; 82 electric motor; 82a
stator; 82b rotor; 83 stator supporting member; 83a shaft insertion
hole; 83b flange; 830b bearing mounting portion; 831b pin mounting
hole; 84 attaching bolt; 85, 86, 87 ball bearing; 88 needle roller
bearing; 90 motor driving force transmission device; 98, 99
movement restricting member; 115 cover; 115a cylindrical portion;
116 seal member; 117 cover; 117a cylindrical portion; 118 seal
member; 101 four-wheel-drive vehicle; 102 engine; 103 transaxle;
104 front wheel; 105 rear wheel; 106 differential carrier; 107 rear
differential; 108 rear axle shaft; 109 front axle shaft; 110
differential case; 110a accommodating space; 110b shaft insertion
hole; 110c external gear; 110d, 110e, 110f, 110g, 110h portion;
110i, 110j external gear; 111 pinion gear shaft; 112 pinion gear;
113 side gear; 114 tapered roller bearing; a first motor driving
force, b second motor driving force, D1, D2, D3, D4 outside
diameter; O rotational axis; O1, O2 point (axis); L axis; .delta.,
.delta.1, .delta.2 deviation amount.
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