New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`VEHICLE WITH ELECTRIC TRANSAXLE
`
`Inventors: Yoshitaka KOCHIDOMARI & Takashi NISHIZAWA
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`BACKGROUNDOF THE INVENTION
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`Field of the Invention
`
`foeed]
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`The present invention relates to a vehicle, such as a utility vehicle,
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`equipped with an electric transaxle integrated with an axle and anelectric
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`motor for driving the axle.
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`BackgroundArt
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`[0002]
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`As disclosed by US 7,946,953 B and US 2010/0263958 A, a
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`conventional engine utility vehicle is equipped with a mid-shipped engine, a
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`rear transaxle casing supporting right and lefi rear wheels, a front transaxle
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`casing supporting right and left
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`front wheels, and a transmission for
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`distributing power of the engine between the front and rear transaxle casings.
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`Each of the front and rear transaxle casings incorporates a differential unit
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`differentially connecting the right and left front or rear wheels to each other.
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`The transmission is combination of a hydrostatic stepless transmission (HST)
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`and a gear transmission, or combination of a belt transmission serving as a
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`continuously variable transmission (CVT) and a gear transmission,
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`for
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`example.
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`[0003]
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`Sometypesofsports utility vehicle are mainly used for hunting purpose.
`Silence is a matter of great importance for hunting vehicles. Therefore, many
`utility vehicles used for hunting are electric vehicles equipped with electric
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`motors. However, hunting vehicles are sometimes desired to have great power,
`such as engine power, for high-speed traveling on road, for high-torque
`traveling on rough fields or for other purposes. Further, recently, people
`dwelling in residential districts greatly demand utility vehicles because the
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`utility vehicles are convenientfor variousdaily livings, e.g., for taking children
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`to and from schoolor kindergarten bas stops. The residents search after silence,
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`

`

`
`
`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`compactness and economyofthe utility vehicles. An electric motor is an
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`effective means for achieving the silence. However,
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`the residents also
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`sometimesdesire the utility vehicles to have great power, such as engine power,
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`for high-speed traveling on road or other purposes.
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`.
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`(oaed]
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`To satisfy the above-mentioned desires, a utility vehicle is expected to
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`have an engine and anelectric motor and to be configured so that either/both
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`electric power or/and engine power can be optionally selected as power for
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`driving the utility vehicle, while ensuring compactness in structure and
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`economy in structure and in power consumption.
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`BRIEF SUMMARYOF THE INVENTION
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`[0005]
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`Anobject of the invention is to provide a vehicle that is adaptable as a
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`compact and economyutility vehicle configured so that either electric power or
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`engine powercan be optionally selected for driving the vehicle.
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`[0006]
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`To achieve the object, a vehicle according to the invention comprises
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`right andleft electric transaxles, right andleft first drive wheels, an engine, right
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`and left second drive wheels, a transmission for transmitting power from the
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`engine to the right and left second drive wheels, a generator, a battery, and a
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`modeselection means. Each of the right and left electric transaxles includes a
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`casing incorporating a drive train and supporting an axle, and includes an
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`electric motor mounted on the casing to drive the axle via the drive train. The
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`right andleft first drive wheels are provided on the axles of the respective right
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`and left electric transaxles. The generator generates electric power by driving
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`the engine. The battery reserves the electric power generated by the generator
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`so as to supply the electric power to the electric motors of the right and left
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`electric transaxles. The mode selection meansis provided for selecting either a
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`first drive mode where only the rightandleft first drive wheels are driven by the
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`electric motors of the respective right and left electric transaxles or a second
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`drive mode where only the right and left second drive wheels are driven by the
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`engine via the transmission.
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`[0007]
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`Therefore, an operator who operates the vehicle can operate the mode
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`selection meansso as to optionally select either the first drive mode for driving
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`the vehicle by only electric power, thereby obtaining silence, or the second
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`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`drive modefordriving the vehicle by only engine power, thereby obtaining high
`torque for efficient traveling of the vehicle. Such an optional selection of drive
`modeis advantageousin achieving an operator’s desired traveling performance
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`of the vehicle as well as or rather than economizing power consumptionofthe
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`vehicle. Further, the vehicle has neither means for transmitting power of the
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`engineto the first drive wheels nor meansfor transmitting powerofthe electric
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`motors to the second drive wheels, thereby being simplified and economized in
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`structure.
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`[0008]
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`These,
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`further and other objects,
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`features and advantages of the
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`invention will appear more fully from the following detailed description with
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`reference to the accompanying drawings.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0009]
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`Fig. 1 is a skeleton diagram of a hybrid vehicle V1 equipped with a pair
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`of electric transaxles ET1 for driving front wheels 14 and with an engine and
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`transmission system 20 for driving rear wheels 24.
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`{0010}
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`Fig. 2 is a plan view partly in section of electric transaxle ET1 used for
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`vehicle V1.
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`[0011]
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`Fig. 3 is a sectional plan view of engine and transmission system 20
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`used for vehicle V1.
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`[0012]
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`[0013]
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`Fig. 4 is a side view partly in section of an electric transaxle ET2.
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`Fig. 5 is a schematic side view ofan electric utility vehicle V2 equipped
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`with electric transaxle ET2 serving as a rear transaxle from which poweris
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`taken off and is transmitted into a front transaxle casing via a propeller shaft.
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`[O014]
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`Fig. 6 is a schematic side view pf a hybrid utility vehicle V3 equipped
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`with electric transaxle ET2 serving as a rear transaxle, and equipped with an
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`engine 80 whose power can be transmitted to the front transaxle casing or/and
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`electric transaxle ET2 serving as the rear transaxle.
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`[0015]
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`Fig. 7 is a fragmentary schematic side view of vehicle V3 equipped with
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`an electric transaxle ET2a serving as a modification ofelectric transaxle ET2.
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`[0016]
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`Fig. 8 is a side view partly in section of an electric transaxle ET2b
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`serving as another modification of electric transaxle ET2.
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`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`[0017]
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`Fig. 9 is a schematic side view pfanelectric utility vehicle V4 equipped
`with electric transaxles ET2b serving as front and rear transaxles.
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`[00138]
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`Fig. 10 is a side view partly in section of an electric transaxle ET2c
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`serving as a modification ofelectric transaxle ET2b.
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`DETAILED DESCRIPTION OF THE INVENTION
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`[0019]
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`Referring to Figs. 1, 2 and 3, a hybrid vehicle (hereinafter, simply
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`referred to as “vehicle”) V1 will be described. Vehicle V1 is a utility vehicle,
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`for example. Vehicle V1 is equipped with a pair of electric transaxles ET]
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`serving as right and left front transaxles for driving respective right and left
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`front wheels 14, and is equipped with an engine and transmission system 20 for
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`driving right and left rear wheels 24. Engine and transmission system 20
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`includes an engine 21, a transaxle casing 22, and a belt transmission BT1 for
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`transmitting power from engine 21 into transaxle casing 22. Right andleft rear
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`wheels 24 are provided on distal ends of respective right and left rear axles 23
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`supported by transaxle casing 22. Transaxle casing 22 incorporates a forward
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`traveling gear train FG, a backward traveling gear train RG, and a differential
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`gear unit D differentially connecting proximal ends ofright and left rear axles
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`23 to each other. Either forward traveling gear train FG or backward traveling
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`gear train RG is selected to transmit power from belt transmission BT1 to
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`differential gear unit D.
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`[0020]
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`Further, vehicle V1 is equipped with a generator 19 that is driven by
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`driving engine 21 so as to generate electric power, and is equipped with a
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`battery 18 for reserving the electric power generated by generator 19 and for
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`supplying the electric power to electric motors 2 of respective electric
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`transaxles ET1.
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`[0021]
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`Referring to Figs. 1 and 2, each of right and left electric transaxles ET1
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`will be described. Electric transaxle ET1 includes a reduction gear casing 1, an
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`axle 12, an electric motor 2, and a reduction gear train RG1 disposed in
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`reduction gear casing | so as to transmit powerfromelectric motor 2 to axle 12.
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`fGG22)
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`Axle 12 is journalled by reduction gear casing 1 via a bearing 16, and is
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`extended outward from reduction gear casing 1 through an opening of reduction
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`gear casing 1 so as to be fixedly provided on a distal end portion thereof with a
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`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`hub 13 that is fixed to a rim 14a of front wheel 14. The opening of reduction
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`gear casing 1 passing axle 12 therethrough is covered with a cover la. Axle 12
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`is formed with a flange 12a on a proximal end portion thereof disposed in
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`reduction gear casing 1, and flange 12ais journalled by reduction gear casing 1
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`via a bearing 15.
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`[0023}
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`Electric motor 2 is fastened to reduction gear casing 1 via a bolt 17 and
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`so on. A motor output shaft 3 of electric motor2 is inserted at a tip thereof into
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`reduction gear casing 1 and is extended coaxially to axle 12. Reduction gear
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`train RG1 interposed between motor output shaft 3 and axle 12 will be detailed.
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`A motoroutput gear 4 is fixed on thetip of motor output shaft 3. A sun gear8 is
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`disposed between the tip of motor output shaft 3 and flange 12a of axle 12
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`coaxially to motor output shaft 3 and axle 12. Sun gear8 is fixedly fitted into a
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`carrier 7 that is disposed betweenthe tip of motor output shaft 3 and flange 12a
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`of axle 12, so that sun gear 8 is rotatably integral with carrier 7. Carrier 7 is
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`extended from sun gear 8 in a radial direction of motor output shaft 3 and axle
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`12, and pivotally supports a planetary gear 5 via a pivot shaft 6 extended parallel
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`to motor output shaft 3 and axle 12. Planetary gear 5 meshes with motor output
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`gear4.
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`[0024]
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`Further, an internal gear 10 is fixed on an inner peripheral surface of
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`reduction gear casing 1, and planetary gear 5 meshes with internal gear 10. On
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`the other hand, flange 12a of axle 12 pivotally supports a planetary gear 9 via a
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`pivot shaft 11 extended parallel to motor output shaft 3 and axle 12. Planetary
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`gear 9 meshes with sun gear 8, and meshes with internal gear 10.
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`In this way,
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`motor output gear 4, planetary gear 5, sun gear 8, planetary gear 9 and internal
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`gear 10 constitute reduction gear train RG1.
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`[0025]
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`Powerof electric motor 2 is transmitted to axle 12 via reduction gear
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`train RG1 in the following way. When motoroutput gear 4 rotates together with
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`motor output shaft 3, planetary gear 5 is rotated by the rotation of motor output
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`gear 4 so as to revolve along internal gear 10 around an axis of motor output
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`shaft 3. The revolution of planetary gear 5 causes rotation of carrier 7 centered
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`on an axis of sun gear 8, thereby causing rotation of sun gear 8 centered onits
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`own axis. Planetary gear 9 is rotated by the rotation of sun gear 8 so as to
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`revolve along internal gear 10 around an axis of axle 12. The revolution of
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`planetary gear 9 causesrotation of flange 12a centered on the axis of axle 12,
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`

`

`NewU.S. Provisional Patent Application
`Our Ref: KK-205P
`
`thereby causingrotation of axle 12 centered on its own axis. In this way, due to
`internal gear 10, the rotation of planetary gear 5 followingthe rotation of motor
`output gear 4 is converted into the revolution of planetary gear 5 such as to
`reduce the rotary speed of sun gear 8, andthen,the rotation of planetary gear 9
`following the speed-reduced rotation of sun gear 8 is converted into the
`revolution of planetary gear 9 suchasto further reduce the rotary speed of axle
`12. Therefore, reduction gear train RG1 has a great reduction gearratio while
`
`[0026]
`
`ensuring its compactness.
`Electric motors 2 of respective right and left electric transaxles ET1 are
`supplied with electric power from battery 18, and their turning on and off and
`their output rotary speedsare controlled by a controller (not shown) provided in
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`vehicle V1. Especially, to turn vehicle V1, the output rotary speedsof electric
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`motors 2 of right and left electric transaxles ET1 are differentially controlled so
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`as to differentially rotate right and left front wheels 14.
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`[0027}
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`Engine and transmission system 20 will be detailed with reference to
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`Figs.
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`1 and 3. Belt transmission BT1 includes a belt transmission cover 25,
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`pulleys 27 and 29 and a belt 28. An engine output shaft 26 of engine 21 is
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`extended into belt transmission cover 25 so as to serve as an input shaft of belt
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`transmission BT1, a transmission input shaft 30 of the gear transmission in
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`transaxle casing 22 is extended outward from transaxle casing 22 in parallel to
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`engine output shaft 26 and into belt transmission cover 25 so as to serve as an
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`output shaft of belt transmission BT1. In belt transmission cover 25, pulley 27
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`is provided on engine output shaft 26, pulley 29 is provided on transmission
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`input shaft 30, and belt 28 is interposed between pulleys 27 and 29. Belt
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`transmission BT1 is a continuously variable transmission (CVT),
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`in which
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`pulleys 27 and 29 are split pulleys, configured so that a ratio of a radius of a
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`looping portion of belt 28 in pulley 27 round engine output shaft 26 to a radius
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`of a looping portion of belt 28 in pulley 29 round transmission input shaft 30 is
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`variable.
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`[0028]
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`Generator 19 is disposed around engine output shaft 26 in belt
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`transmission cover 25. Generator 19 includes a stator 21a fixed to engine 21,
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`and includesa rotor 27afixed to pulley 27. Stator 21a is provided with armature
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`windings 21b, and rotor 27a is provided with magnets 27b. Stator 21a and rotor
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`27a are disposed so that magnets 27b face armature windings 21b. Therefore,
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`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`whenstator 27a rotates together with engine output shaft 26, armature windings
`27a are excited by rotating magnets 27b so as to generate electric power to be
`
`[0029]
`
`reserved in battery 18.
`In transaxle casing 22, transmission input shaft 30, a counter shaft 31,
`andright and let coaxial axles 23 are extendedin parallel and are journalled by
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`transaxle casing 22 via bearings.
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`In detail, transaxle casing 22 includes right
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`and left gear housings 22a and 22b andright and left brake housings 22c¢ and
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`22d. Right and left gear housings 22a and 22b are joined to each other at a
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`vertical joint plane so as to define a gear chamber of transaxle casing 22
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`incorporating forward traveling gear train FG, backwardtraveling gear train RG
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`and differential gear unit D. Right brake housing 22c is joined to right gear
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`housing 22a so as to extend rightward from right gear housing 22a, thereby
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`journaling right axle 23 via bearings, and thereby defining a right brake
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`chamberoftransaxle casing 22 incorporating a right brake 44 for braking right
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`axle 23. Left brake housing 22d is joined to left gear housing 22b so as to
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`extend leftward from left gear housing 22b, thereby journaling left axle 23 via
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`bearings, and thereby defining a left brake chamber of transaxle casing 22
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`incorporating a left brake 44 for braking left axle 23. Right and left axles 23
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`project rightwardly and leftwardly outward from right and left brake housings
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`22c and 22d, respectively, so as to be provided on respective distal ends thereof
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`with respective right and left rear wheels 24.
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`[0030]
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`In each of the right and left brake chambers of transaxle casing 22,
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`friction discs that are unrotatable relative to corresponding axle 23 and friction
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`discs that are unrotatable relative to transaxle casing 22 are alternately aligned
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`so as to constitute each of right and left brakes 44. A brake shoe 45 is disposed
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`in each ofthe right and left brake chambers between each brake 44 and each of
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`right and left gear housings 22a and 22b. Right and left brake arms 46 are
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`pivoted on outer portions of respective right and left brake housings 22c and
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`22d, and are operatively connected to respective brake shoes 45 and to a brake
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`manipulator (not shown) of vehicle V1. When the brake manipulator is
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`operated for braking, brake arms 46 are rotated to move respective brake shoes
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`45 toward respective brakes 44 so as to press the friction discs of respective
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`brakes 44 against one another, thereby applying brakes 44 to stop right andleft
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`axles 23. When the brake manipulator is operated for unbraking, brake arms 46
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`

`

`New USS. Provisional Patent Application
`Our Ref: KK-205P
`
`are rotated to move respective brake shoes 45 away from respective brakes 44
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`so as to separate the friction discs of respective brakes 44 from one another,
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`thereby allowingrotation of right and left axles 23 freely from respective brakes
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`44.
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`[0031]
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`In the gear chamberof transaxle casing 22, a centrifugal governor 47 is
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`provided on transmission input shaft 30. Centrifugal governor 47 detects the
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`rotary speed of transmission input shaft 30 (serving as the output shaft of belt
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`transmission BT1) and controls engine 21 to change the rotary speed of engine
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`output shaft 26 (serving as the input shaft of belt transmission BT1) in
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`correspondenceto the detected rotary speed of transmission input shaft 30.
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`[0032]
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`In the gear chamber of transaxle casing 22, a forward traveling drive
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`gear 32 and a backwardtraveling drive gear 33 are formed (or fixed) on
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`transmission input shaft 30.
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`In the gear chamber of transaxle casing 22, a
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`forward traveling driven gear 34 and a backward traveling driven gear 35 are
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`fitted on counter shaft 31 so as to be rotatable relative to counter shaft 31.
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`Forwardtraveling drive gear 32 and forward traveling driven gear 34 mesh with
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`each other so as to constitute forward traveling gear train FG. Backward
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`traveling drive gear 33 and backward traveling driven gear 35 mesh with an idle
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`gear (not shown) so that backward traveling drive gear 33, the idle gear and
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`backward traveling driven gear 35 constitute backward traveling gear train RG.
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`Further, a pinion 37 is formed(or fixed) on counter shaft 31 so as to transmit the
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`rotary force of counter shaft 31 to later-discussed differential gear unit D.
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`[0033]
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`Counter shaft 31 is formed with a spline portion between gears 34 and
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`35, and a reverser shifter 36 is spline-fitted on the spline portion of countershaft
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`31 so that reverser shifter 36 is unrotatable relative to counter shaft 31 and is
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`axially slidable on counter shaft 31. Gears 34 and 35 are formed with notches in
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`respective portions thereof facing reverser shifter 36. Reverser shifter 36 is
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`formed on axial opposite ends thereof with teeth to befitted into the notches of
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`respective gears 34 and 35. The notches of forward traveling driven gear 34 and
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`the teeth on one end ofreverser shifter 36 facing forward traveling driven gear
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`34 constitute a dog clutch for forward traveling rotation of axles 23. The
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`notches of backward traveling driven gear 35 and the teeth on the other end of
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`reverser shifter 36 facing backward traveling driven gear 35 constitute a dog
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`clutch for backwardtraveling rotation of axles 23.
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`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`[0034]
`
`Reverser shifter 36 can be shifted among a forward traveling position, a
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`neutral position and a backward traveling position. When reversershifter 36 is
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`disposed at the forward traveling position, the teeth on one end of reverser
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`shifter 36 are fitted into the notches of forward traveling driven gear 34 so as to
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`rotatably integrate forward traveling driven gear 34 with counter shaft 31 via
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`reverser shifter 36, so that the rotary force of transmission input shaft 30 driven
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`by engine 21 via belt transmission BT1 is transmitted to counter shaft 31 via
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`forward traveling gear train FG, thereby rotating axles 23 in the forward
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`traveling rotation direction of rear wheels 24.
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`hen reverser shifter 36 is
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`disposed at the backward traveling position (as shown in Fig. 3), the teeth on the
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`other end of reverser shifter 36 are fitted into the notches of backward traveling
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`driven gear 35 so as to rotatably integrate backward traveling driven gear 35
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`with counter shaft 31 via reverser shifter 36, so that the rotary force of
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`transmission input shaft 30 is transmitted to counter shaft 31 via backward
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`traveling gear train RG, thereby rotating axles 23 in the backward traveling
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`rotation direction of rear wheels 24. Whenreverser shifter 36 is disposed at the
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`neutral position (as shownin Fig. 1), neither forward traveling driven gear 34
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`nor backward traveling driven gear 35 hasthe teeth of reverser shifter 36 in the
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`notches thereof, so that gears 34 and 35 are allowed torotate relative to counter
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`shaft 31, thereby preventing the rotary force oftransmission input shaft 30 from
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`being transmitted to counter shaft 31, and thereby making axles 23 free from the
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`powerof engine 21.
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`[0035]
`
`In the gear chamber of transaxle casing 22, differential gear unit D
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`differentially connects proximal end portions of right and left axles 23 to each
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`other. Differential gear unit D includes a differential input gear (bull gear) 38, a
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`differential casing 39, a pivot shaft 40, bevel differential pinions 41 and right
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`and left bevel differential side gears 42. Right and left axles 23 are journalled
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`by respective right and left gear housings 22a and 22b via respective bearings
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`and are extended at the respective proximal ends thereof into the gear chamber
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`of transaxle casing 22 so as to be inserted into differential casing 39, so that
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`axles 23 are rotatable relative to differential casing 39. In differential casing 39,
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`right and left bevel differential side gears 42 are fixed on the proximal ends of
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`respective right andleft axles 23.
`
`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`[0036]
`
`Differential input gear 38 is fixed on differential casing 39 and meshes
`with pinion 37 on counter shaft 31. Pivot shaft 40 is extended in a radial
`
`direction of axles 23, andis fixed to differential casing 39 so as to be rotatably
`
`integral with differential casing 39 and differential input gear 38..Bevel
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`differential pinions 41 are pivoted on pivot shaft 40. Each of bevel differential
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`pinions 41 meshes with both right andleft differential side gears 42.
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`[0037]
`
`Due to the above-mentioned structure, transmission input shaft 30
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`receives the power of engine 21 via belt transmission BT1, and in transaxle
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`casing 22, either forward traveling gear train FG or backward traveling gear
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`train RG is selected by reverser shifter 36 so as to transmit the power of engine
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`21 from transmission input shaft 30 to counter shaft 31, thereby transmitting
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`the powerof engine 21 from counter shaft 31 to right and left rear wheels 24 via
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`pinion 37, differential gear unit D and right andleft axles 23.
`
`[0038]
`
`As understood from the above-mentioned structure and Fig. 1, vehicle
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`V1 is provided with neither means for distributing the power of engine 21 to
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`front wheels 14 nor meansfor distributing the powerof electric motors 2 to rear
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`wheels 24. This is because vehicle V1 rather sets importance on the advantages
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`in structural simplicity and reduction of components and costs. Assumptive
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`driving modesof vehicle V1 are two types of 2WD (two wheel drive) mode: a
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`first 2WD modeto drive vehicle V1 by driving only rear wheels 24 by powerof
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`engine 21; and a second 2WD modeto drive vehicle V1 by driving only front
`
`wheels 14 by powerofelectric motors 2.
`
`[0039]
`
`In this regard, vehicle V1 is provided with a mode selection means,e.g.,
`
`a switch, a button,a dial, a lever or a pedal, whichis operatedto select either the
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`first 2WD mode where only rear wheels 24 are driven by engine 21 or the
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`second 2WD mode whereonly front wheels 14 are driven by electric motors2.
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`Therefore, an operator who drives vehicle V1 can optionally select either the
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`first 2WDfor obtaining silence or the second 2WDfor obtaining high power.
`
`[0040]
`
`Various changes and modifications may be made in vehicle V1. For
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`example, vehicle V1! may be alternatively provided with engine and
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`transmission system 20 for driving right and left front wheels 14 and with the
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`pair of electric transaxles ET1 for driving right and left rear wheels 24. Further,
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`it is possible that vehicle V1 can travel in 4WD (for wheel drive) mode, where
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`front wheels 14 are driven by electric motors 2 of electric transaxles ET1 and
`
`10
`
`

`

`New U.S. Frovisional Patent Application
`Our Ref: KK-205P
`
`simultaneously rear wheels 24 are driven by engine 21 of engine and
`
`transmission system 20, if rotary speeds of front wheels 14 and rear wheels 24
`
`can be equalized well. Incidentally, if vehicle V1 is provided with means,e.g.,
`a propeller shaft and universal joints, for transmitting power from electric
`
`motors 2 to rear wheels 24 and/orfor transmitting power from engine 21 to front
`
`wheels 14, front wheels 14 can be driven by combined powers of electric
`
`motors 2 and engine 21 and/or rear wheels 24 can be driven by combined
`
`powers of engine 21 and electric motors 2.
`
`[0041]
`
`Referring to Fig.4, an electric transaxle ET2 will be described. Electric
`
`transaxle ET2 is defined as a transaxle integrated with an electric motor 51.
`
`Electric transaxle ET1 includes a reduction gear casing 52, a differential gear
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`casing 53, and a powertaking-off (PTO) casing 54. Reduction gear casing 52
`
`includes a main housing 52a and a cover 52b joined to each other. Electric
`
`motor 51 and differential gear casing 53 are fixed to main housing 52a of
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`reduction gear casing 52 so as to be cantilevered from reduction gear casing 52
`
`in the same direction. PTO casing 54 is fixed to cover 52b of reduction gear
`
`casing 52 so as to extend from reduction gear casing 52 opposite to electric
`
`motor 51 and differential gear casing 53. Hereinafter, it is assumedthat electric
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`motor 51 and differential gear casing 53 are extended rearward from reduction
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`gear casing 52, and PTO casing 54 is extended forward from reduction gear
`
`casing 52.
`
`[0042]
`
`Electric motor 51 has a motor output shaft 51a that is extended into
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`reduction gear casing 52. A motor output pinion 51b is fixed on motor output
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`shaft 51a in reduction gear casing 52. A gear member 55 is formed with a
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`cup-shaped portion and with an axial shaft 55a extended from the cup-shaped
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`portion thereof. Gear member55 is disposed in reduction gear casing 52 so as
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`to have axial shaft 55a journalled by cover 52a via bearings 66. Axial shaft 55a
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`of gear member55 is extended in the axial direction of motor output shaft 51a,
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`however, is axially offset from motor output shaft 51a in the radial direction of
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`motor output shaft 51a, i.e., is not coaxial to motor output shaft 51a.
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`[9043]
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`An inner peripheral surface of the cup-shaped portion of gear member
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`55 is toothed to form an inner peripheral gear 55b, and an outer peripheral
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`surface of the cup-shaped portion of gear member 55 is toothed to form an outer
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`peripheral gear 55c. Motor output shaft 51a is inserted into the cup-shaped
`
`li
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`

`

`New U.S. Provisional Patent Application
`OurRef: KK-205P
`
`[0044]
`
`portion of gear member55 so that motor output pinion 51b meshes with inner
`peripheral gear 55b of gear member55.
`Motor output pinion 51b and inner peripheral gear 55b constitute a
`reduction gear train that is advantageous in its compactness and its large
`reduction gear ratio. More specifically, when viewed in the axial direction of
`motor output shaft 51a and axial shaft 55a, motor output pinion 51b is disposed
`within a circle defined by inner peripheral gear 55b, thereby achieving the
`compactness, especially, minimizing the gear arrangement in radial directions
`of axial shaft 55a. Further, even in the case that the diametrical size of gear
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`member 55 (i.e., the diameter of inner peripheral gear 55b) is limited, the
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`diametrical difference between motor output pinion 51b and inner peripheral
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`gear 55b can be increased by reducing the diametrical size of motor output
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`pinion 51b,
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`thereby ensuring a large reduction gear ratio as well as the
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`compactness.
`
`[0045]
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`However, it should be considered that as the diametrical size of motor
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`output pinion 51b is reduced, the axial offset degree of electric motor 51 from
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`gear member55 (i.e., the deviation of motor output shaft 51a from axial shaft
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`55a in the radial direction of gear member55)is increased. Therefore, to allow
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`the diametrical size reduction of motor output pinion 51b relative to inner
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`peripheral gear 55b for ensuring the large reduction gearratio, electric transaxle
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`ET2 is configured so that electric motor 51 can be mounted on a portion of
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`reduction gear casing 52 such as to ensure the required axial offset degree of
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`electric motor 51 from gear member55 in reduction gear casing 52.
`
`[0046]
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`A final reduction gear 56 is disposed in reduction gear casing 52 and
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`mesheswith outer peripheral gear 55c of gear member 55. As a result, motor
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`output pinion 51b, inner peripheral gear 55b, outer peripheral gear 55c andfinal
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`reduction gear 56 constitute an entire reduction gear train RG2 in reduction gear
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`casing 52. Final reduction gear 56 is fixed on a reduction output shaft 57.
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`Reduction output shaft 57 is journalled by main housing 52a of reduction gear
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`casing 52 via a bearing 67, and is journalled by cover 52b of reduction gear
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`casing 52 via a bearing 68 so as to extendin the axial direction of motor output
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`shaft 51a. A rear end portion of reduction output shaft 57 is inserted into
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`differential gear casing 53 via main housing 52a of reduction gear casing 52. A
`
`12
`
`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205F
`
`bevel pinion 37ais formed on the rear end portion of reduction output shaft 37
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`in differential gear casing 53.
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`(0047)
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`A differential gear unit 58 is disposed in differential gear casing 53 so as
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`to differentially connect proximal ends of right and left axies 59 to each other.
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`Differential gear unit 58 has a bevel input gear 58a that meshes with bevel
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`pinion 57a, Right and left axles S9 are journalled by differential gear casing 53
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`and are extended rightwardly and leftwardly (perpendicular to the axial
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`direction of motor output shaft 51a) outward from differential gear casing 53.
`
`[0048]
`
`PTOcasing 54 is formed in a rear portion thereof with a clutch chamber
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`54a, and is formedin a front portion thereof with a PTO shaft chamber 54b that
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`is opened forwardly outward. A PTOshaft 61 is journalled via a bearing 69 by a
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`partitioning wall of PTO casing 54 formed between chambers 54a and 54b. A
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`rear end portion 6fb of PTO shaft 61 is splined on an outer peripheral surface
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`thereef, and is formed therein with a rearwardly opened recess 6la. Rear end
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`portion 61b of PTO shaft 61 is disposed in clutch chamber 54a. A front end
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`portion 6lc of PPO shaft 61 is splined on an outer peripheral surface thereof,
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`and is disposed in PTO chamber 546. A front portion 37b of reduction output
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`shaft 57 is splined on an outer peripheral surface thereof, and is disposed in
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`cluich chamber 54a. A front end projection 57c that is diametrically smaller
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`than splined front portion 57b of reduction output shaft 57 projects forward
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`from splined front portion 57b, andis inserted into recess 61a of PTO shaft 61 in
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`clutch chamber 54a, so that reduction output shaft 57 is rotatable relative to
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`PTOshaft 61.
`
`[0049]
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`A clutch 60 is interposed between reduction output shaft 57 and PTO
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`shaft 61 in clutch chamber 54a. Clutch 60 includes a clutch slider 62, a spline
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`hub 63, a detent assembly 64 and a spacer 65. Spline hub 63is fixed on splined
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`front portion 57b of reduction output shaft 57, and spacer 65 is fixed on
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`reduction output shaft 57 between spline hub 63 and cover 52b ofreduction gear
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`casing 52. Clutch slider 62 is fitted on the splined outer peripheral surface of
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`rear end portion 61b of PTO shaft 61 so asto be axially slidable on PTO shaft 61
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`and so as to be unrotatable relative to PTO shaft 61. Detent assembly 64
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`includes a pair of balls and a compressed spring sandwiched betweenthe balls,
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`andis fitted in a diametric through hole of PTO shaft 61, so that the balls are
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`pressed against clutch slider 62 by the spring.
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`13
`
`

`

`New U.S. Provisional Patent Application
`Our Ref: KK-205P
`
`[0050]
`
`Clutch slider 62 can be shifted between a clutch-on position and a
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`clutch-off position, and can be held at either the cl