USRE36678E - Hybrid vehicle - Google Patents

Abstract

A hybrid vehicle having an internal combustion engine, a generator connected with an output shaft extending from the internal combustion engine, an electric motor axially aligned with the output shaft, an output gear assembly connected to an output shaft driven by the rotor of the electric motor and positioned between the generator and the electric motor, a clutch adapted to connect and disconnect the generator to/from the output gear assembly, a differential gear unit, and a counter shaft oriented in parallel the output shaft driven by the rotor.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a vehicle having a hybrid power source operationally combining an internal combustion engine, such as a gasoline engine, diesel engine or gas-turbine engine, with an electric motor operating off current stored in a battery mounted in the vehicle and, more particularly, to an assembly including the internal combustion engine, a generator and the electric motor in a hybrid vehicle.

2. Description of the Related Art

The present invention can be applied both to a series type assembly and a parallel type assembly. Three types of hybrid arrangement are known. The first type is the series type assembly in which the hybrid vehicle moves under power of the electric motor operating on current generated by the generator driven by the internal combustion engine which is constantly running. The second type is the parallel type assembly in which both the internal combustion engine and the electric motor are arranged to relate to the drive wheels, but are selectively used. The third type is the series-parallel type assembly combining the series type and parallel type assemblies.

The conventional hybrid vehicle of the series type assembly has the internal combustion engine and the generator integrally combined and the electric motor or an electric motor and transmission unit separated therefrom. A motor vehicle typically mounts the electric motor and the transmission at its front portion, the internal combustion engine and the generator at its rear and the battery intermediate the front and rear.

However, in a passenger car, the internal combustion engine (with the generator), provided at the front of the vehicle, is cooled by ram air. Accordingly, the battery should be located either at the intermediate or rear portion of the vehicle. In consideration of providing sufficient interior space for passengers and a practical traveling distance on one battery charge, several batteries are typically arranged at the rear portion of the vehicle.

It has therefore been preferable to install the electric motor and the transmission unit at the front of the vehicle in a total plan for weight balance and interior space for passengers.

A certain clearance between the internal combustion engine and generator unit and the electric motor and transmission unit should be provided because the two units should be mounted in the vehicle separately to appropriately relate to different drive components and systems causing vibration, which separation requires a large space for the internal combustion engine, generator, electric motor and transmission unit in the vehicle. In the series type hybrid vehicle, such a disadvantage is conspicuous due to a relatively large generator, so that an arrangement aligning the internal combustion engine, generator, electric motor and transmission all together in an engine compartment at the front of the vehicle is impossible.

Even if such an arrangement could be fit into the engine compartment, somehow or other, the steering angle required for the front wheels to turn requires a large clearance circle and further requires separate cases for the internal combustion engine, generator, electric motor and transmission unit, which results in an increase in the number of parts, in weight and in the cost for manufacturing.

Giving precedence to the internal combustion engine and 35 the generator, the electric motor and the transmission unit are difficult to locate at the central portion of the vehicle, whereby the differential gear unit receiving driving power from the electric motor also tends to be located off-center of the vehicle, so that shafts laterally and oppositely extending from the differential gear unit have different lengths which causes a torque on the steering.

SUMMARY OF THE INVENTION

An object of the present invention is to arrange the generator and the electric motor in alignment and within an integrated case to reduce the required longitudinal dimension of the hybrid vehicle.

To attain the foregoing object, a hybrid vehicle according to the present invention has: (a) an internal combustion engine; (b) a generator connected with an output shaft extending from the internal combustion engine, the generator including a magneto stator and a rotor driven by the magneto stator; (c) an electric motor axially aligned with the output shaft extending from the internal combustion engine, the electric motor including a magneto stator and a rotor driven by the magneto stator; (d) an output gear assembly connected to an output axle shaft driven by the rotor of the electric motor and located between the generator and the electric motor; (e) a clutch adapted to connect and disconnect the generator to/from the output gear assembly; (f) a differential gear unit; and (g) a counter shaft oriented in parallel to the output shaft related to the rotor, the counter shaft including gears transmitting a torque from the output gear assembly to the differential gear unit.

The output shaft related to the rotor of the electric motor is provided with an automatic transmission unit after the rotor of the electric motor, so that the rotational speed of the rotor of the electric motor is transmitted to the output shaft connected with the output gear assembly. The automatic transmission unit includes at least one planetary gear unit and is arranged to operate as an under-drive unit.

The automatic transmission unit should also include a hydraulic wet clutch.

The output shaft from the internal combustion engine is connected with the rotor of the generator through a damper.

The generator includes a speed-increasing gear assembly in the interior thereof, so that the rotational speed of the output shaft of the internal combustion engine is accelerated and transferred to the rotor of the generator. The speed-increasing gear assembly of the generator is in the form of a planetary gear unit. Furthermore, the output shaft from the internal combustion engine is connected with the speed-increasing gear assembly of the generator through a damper.

The output gear assembly arranged between the generator and the electric motor is smaller in size than both the generator and the electric motor.

The generator, the electric motor and the output gear assembly are arranged to be received all together in an integrated casing. The integrated casing is abutted against the internal combustion engine. The integrated casing includes three members, the first member being adapted to receive the generator, the second member being adapted to receive the output gear assembly, and the third member being adapted to receive the electric motor. The stator of the generator should be fixed to the first member of the case and the stator of the electric motor is fixed to the third member of the case.

The clutch is preferably a hydraulic wet clutch.

According to the present invention, the generator, electric motor and transmission unit are aligned with an output shaft extending from the internal combustion engine and all are received in the integrated casing, whereby a single anti-rattle means is sufficient due to the unified vibration generated by them. The integrated arrangement of the internal combustion engine and the electric motor does not require a space between them to prevent interference but, rather, minimizes the longitudinal dimensions thereof.

Furthermore, the rotation of the internal combustion engine is mainly transmitted to the generator and that of the electric motor goes to the differential gear unit via the transmission gear unit and the output shaft located in the central portion of the casing, so that the power transmitting path is short and the shafts laterally and oppositely extending from the differential gear unit have the same length to avoid torque on the steering and thereby improve reliability of power transmission.

Because the generator is secured on the integrated casing adjacent the internal combustion engine, the rotor thereof can be securely and rotatably supported at both ends.

The integrated casing housing the generator, electric motor and transmission gear unit and the shortened power transmitting path contribute to a decrease in the number of parts, in weight and in manufacturing cost.

Use of a generator in place of a torque converter in a front-wheel front-drive vehicle, allows the system according to the present invention to be manufactured in already existing facilities for assembling transmission units. The shafts conventionally applied to the differential gear unit can be replaced to easily start production line work.

As the electric motor is located spaced from the internal combustion engine, design of the electric motor may be freely changed without changing the arrangement of the internal combustion engine and generator.

With optional provision of a clutch between the generator and the transmission unit, the series type hybrid vehicle can be used in high speed cruising, just as a parallel type vehicle and, if necessary, the vehicle can be propelled without the generator.

By providing a speed increasing gear assembly inside of the rotor, the generator offers the advantages of shortening the axial length and allowing generation of an effectively higher voltage by the generator.

Locating the transmission unit inside of the rotor of the electric motor provides the advantages of shortening the longitudinal length and not restricting design of the electric motor since there are no limitations dictating radial or longitudinal dimensions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the hybrid unit according to a first embodiment of the present invention;

FIG. 2 is a sectional view of the first embodiment;

FIG. 3 is a schematic view of the hybrid unit according to a second embodiment of the present invention;

FIG. 4 is a sectional view of the second embodiment;

FIG. 5 is a sectional view of a generator in combination with a planetary gear assembly; and

FIG. 6 is a schematic view illustrating an arrangement of the hybrid unit and a battery in a hybrid vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

A first preferred embodiment of the present invention will now be described with reference to FIGS. 1 and 2.

An engine compartment provided at a front portion of the vehicle houses an internal combustion engine (hereinafter referred to as "engine") 1, such as a gasoline or diesel engine, which is transversely mounted, and ahybrid unit 2, which replaces a conventional automatic-transmission unit and receives output of the engine 1. Thehybrid unit 2 has anintegral case 3 which abuts one end of the engine and is defined by three sections (3A, 3B, 3C).Case 3 houses agenerator 6, aclutch 7, a two-speedautomatic transmission unit 9 and an electric motor in alignment with output shaft la of the engine 1. Adifferential gear unit 11 is mounted under thecase 3.

Thegenerator 6 is provided, in place of the torque converter of the conventional automatic transmission unit, adjacent to the engine 1 in agenerator housing 3A forming one section of theintegral case 3. Thegenerator 6 has astator coil 12 fixed to the housing and arotor 15 connecting to the output axle 1a via adamper 13. Thedamper 13, located radially inward of thestator coil 12, includes aninput element 13a connected to the output axle 1a, anoutput element 13b connected to therotor 15 and plural springs 13c provided therebetween. Therotor 15 includes aboss portion 15a, ahub 15b and amagnetic member 15c wound around the outer circumferential surface of the hub. Thehub 15b is secured to thedamper 13 and theboss 15a has a cylindrical shape and is fitted over aspline shaft 17.

Theclutch 7 is a hydraulic-wet multiple disk clutch having an input section connected to thespline shaft 17 and an output section connected to anintermediate shaft 21 extending toward theautomatic transmission unit 9. Theintermediate shaft 21 is rotatably supported in a cylindrically shapedoutput axle 22 which, in turn, is connected to acounter drive gear 23 at its distal end near theclutch 7. As can be seen from FIG. 2, theclutch 7 and thecounter drive gear 23 are arranged near the central portion of thecase 3 or, more particularly, incentral case section 3B, i.e. in an area encircled by anannular flange 3a (shown partially cut off). At the forward end of theannular flange 3a, there is attached apump case 19 adjacent a side wall of thegenerator housing 3A. Thepump case 19 houses an internal gear pump for supplying a hydraulic fluid toclutches 7 and C2 and to a brake B and for lubricating moving parts of thehybrid unit 2.

The two-speedautomatic transmission unit 9 includes an under-drive mechanism (U/D) with a singleplanetary gear unit 25 including a ring gear R, which is connected to theintermediate shaft 21, and a carrier CR fixed to theoutput shaft 22. A direct clutch C2, in the form of a hydraulic-wet multiple disk clutch, is arranged between the carrier CR and a sun gear S. A hydraulic multiple disk type brake B for slow speed and a one-way clutch F are arranged in parallel between the sun gear S and thecase section 3B.

Theelectric motor 10 is a hollow motor, such as a brush-less DC motor, induction motor or direct current shunt motor, and is mounted in amotor case section 3C, isolated from the engine 1. Theelectric motor 10 is defined by aflat stator 26 and aflat rotor 27, thestator 26 being secured to the inner wall surface of themotor case section 3C and wound with acoil 28, and therotor 27 being connected to theintermediate shaft 21 and the ring gear R of theplanetary gear unit 25. Theelectric motor 10 defines a large central interior space A for accommodating the two-speedautomatic transmission unit 9. Incidentally, thetransmission unit 9 is not housed entirely within central space A, but extends into thecase section 3B.

In the lower portion of thegenerator housing 3A and thecase section 3B, is mounted acounter shaft 29 with output todifferential gear unit 11. Thecounter shaft 29 is provided with a counter drivengear 30, meshing with thedrive gear 23, and apinion gear 31. Thedifferential gear unit 11 further comprises aring gear 32 meshing with thepinion gear 31 to transmit torque to the laterally extendingfront shafts 33a and 33b, respectively, in different ratios, from thering gear 32. Incidentally, in a sectional end view, the spline shaft 17 (21, 22), thecounter shaft 29 and twofront shafts 33a, 33b would be seen oriented at respective vertexes of a triangle.

As can be seen from the drawings, the radii of thecounter drive 23 and of the clutch 7 are smaller than those of thegenerator 6 and theelectric motor 10 and the outer diameter of theannular flange 3a encircling them is smaller than those of thegenerator housing 3A and themotor case 3C. Thepinion gear 31 secured to thecounter shaft 29 is arranged close to theclutch 7 and, more particularly, centered between the twoshafts 33a and 33b. Thepinion gear 31 is meshed with thering gear 32 securely attached to differential case 11a of thedifferential gear unit 11 which, in turn, is centered between the twoshafts 33a and 33b driving, respectively,wheels 49a and 49b.

Theboss 15a of thegenerator 6 is rotatably supported by aslide bearing 35 at its forward end and by thesplined shaft 17 through acap 36 at its rear end. Thesplined shaft 17 is supported in asleeve 19a, extending at one end through thepump case 19, through slidingbearings 37, 39. Accordingly, theboss 15a can be supported, at its forward end, on the rigidly mountedpump case 19 and, at its rear end, by thesplined shaft 17 at two points. It should be understood that as thesplined shaft 17 and therotor 15 are connected to rotate as a single unit, therotor 15 does not rotate relative to thesplined shaft 17.

Lubricating oil is fed through acentral oil path 41 of theintermediate shaft 21, through anoil path 40 of themotor case 3C and through plural radially extending holes 41a in theintermediate shaft 21 and also into lubricatingoil path 42 of thepump case 19. The lubricating oil from theoil path 42 flows through a gap a between thesplined shaft 17 and thesleeve 19a to lubricate the slidingbearings 37, 39, through a hole b to a slidingbearing 35 and through a hole d and a center hole e of theshaft 17 to the cap 36 (See, FIGS. 2 and 7).

Since thegenerator 6, theelectric motor 10 and theautomatic transmission unit 9 are installed all together in thecase 3, a single lubricating pool is sufficient to lubricate and cool thegenerator 6 as well as the automatic 10transmission unit 9.

Incidentally, FIG. 1, also shows abattery 45, aconverter 46 for conversion of alternating current into direct current and aninverter 47 for controlling the electrical current to theelectric motor 10.

FIG. 8 is a plan view schematically showing the hybrid vehicle according to the present invention in an arrangement wherein the engine 1, thegenerator 6, theelectric motor 10 and theautomatic transmission unit 9 are all installed transversely in the engine compartment, in this order, with adifferential gear unit 11 mounted via thecounter gear arrangement 29, 30, 31 located in about the center of the whole. As has been described above, thedifferential gear unit 11 is centrally located between the drivingshafts 33a and 33b to transmit rotation to thefront wheels 49a and 49b. Thebattery 45 is located at the rear of the vehicle betweenrear wheels 50a and 50b (see FIG. 6).

The invention facilitates an operative sequence as will be explained in more detailed below.

In normal operation, theclutch 7 is released to isolate the rotation of theintermediate shaft 21 from that of theshaft 17 driven by the engine 1. The engine 1 is occasionally started by operation of a switch control by an operator for running at a constant speed, determined to suppress exhaust gas while achieving high efficiency, both in short stops and in running. The rotation of the engine 1 is transmitted to therotor 15 of thegenerator 6 via thedamper 13 to generate a predetermined electrical current in thestator coil 12. The thus-generated electrical power is stored in the battery 4 via theconverter 46. The rotation of engine 1 also produces an oil pressure by driving the oil pump housed in thecase 19, via theboss 15a.

The electrical current from thebattery 45 and/orconverter 46 is supplied to theelectric motor 10 via theinverter 47 responsive, for example, to operation of an accelerator pedal. The speed of rotation of therotor 27 of theelectric motor 10 is changed by theautomatic transmission unit 9 based on the throttle opening and the speed of travel and thereafter transmitted to theoutput shaft 22. More particularly, in first speed, the direct clutch C2 is released but the one-way clutch F is engaged. The rotation of therotor 27 drives the ring gear R which, in turn, drives the pinion P of the carrier CR at a relatively reduced speed to thereby rotate theoutput shaft 22 as the under-drive mode. In regenerative braking, the brake B is operated to stop the sun gear S so that the rotation of theoutput shaft 22 is transmitted to therotor 27.

In second speed, the direct clutch C2 is engaged so that the motion of the sun gear S is integrated with that of the carrier CR to thereby rotate thegear unit 25, which results in an integral rotation of therotor 27 and theoutput shaft 22.

The thus-rotatedoutput shaft 22 drives thecounter drive gear 23, the counter drivengear 30 and thepinion gear 31, in succession, and this rotation is finally transmitted to thedifferential gear unit 11 to rotate thefront wheel shafts 33a and 33b.

Under a high load torque when starting, accelerating or climbing, theautomatic transmission unit 9 maintains first speed to maximize the torque from theelectric motor 10. For high speed cruising, theautomatic transmission unit 9 shifts to the second speed state, under conditions where theelectric motor 10 will not be required to cope with any high load torque.

As has been mentioned above, this embodiment is a series type assembly which normally drives the vehicle by theelectric motor 10 but, when theelectric motor 10 is out of order or the vehicle is to be run at a high speed on a highway, theclutch 7 is activated, either by the operator or automatically, whereby the output of theelectric motor 10 is converted to an arrangement in parallel with the engine output. In this state, the rotation of the output axle 1a is not only transmitted to therotor 15 via thedamper 13, but also to theintermediate shaft 21 via thespline shaft 17 and the engagedclutch 7, with input to the ring gear R of theautomatic transmission unit 9. It is therefore possible not to use theelectric motor 10 while the rotation of the engine 1 is being transmitted to theautomatic transmission unit 9.

FIGS. 3 and 4 depict a second embodiment according to the present invention. Incidentally, in the description of the following embodiments, the same reference numerals will be used to designate the same or similar components as those in the first embodiment, so that the description will be omitted or simplified.

The difference between this second embodiment and the first embodiment is in the addition of a speed increasinggear assembly 52 in thegenerator 6. The speed increasing gear assembly is a single planetary gear unit by which the output of shaft 1a of the engine 1 is transmitted to the carrier CR via adamper 13, the ring gear R2 is connected to therotor 15 and the sun gear S2 is secured on thepump case 19 via thesleeve 19a. The carrier CR2 is slipped over thespline shaft 17.

As shown in FIG. 5, the lubricating oil from the lubricatingoil path 42 from the pump housed incase 19 is fed to a carrier oil path f of theplanetary gear unit 52 through the aperture a between thespline shaft 17 and thesleeve 19a and the oil path d, e of theshaft 17 and then fed into the oil path g of the pinion shaft via anoil pan 53. The lubricating oil is also fed to the slidingbearing 37 from the aperture a, fed to the slidingbearing 35 through the hole b, supplied to an aperture i between the sleeve 10a and theboss 54 through the hole h and fed to thebearings 55, 56, 57 via the oil path j.

Accordingly, the rotation of the output shaft 1a of the 5 engine 1 is transmitted to the carrier CR2 of the speed-=increasinggear assembly 52 viadamper 13. The speed-increasinggear assembly 52 accelerates the rotational speed of the ring gear R2 because the sun gear S2 is temporarily stopped, therotor 15 connected to the ring gear R2 is accelerated relative to thecoil 12. Accordingly, thegenerator 6 generates a high voltage to charge thebattery 45 via theconverter 46. The speed-increasinggear assembly 52 is located inside of therotor 15 without changing the dimensions of thegenerator 6 to allow for preferred lubrication and cooling.

The speed-increasinggear assembly 52 may be of a double-pinion planetary gear unit instead of the single planetary gear unit used in the above mentioned embodiments.

Theautomatic transmission unit 9 provided intermediate therotor 27 of theelectric motor 10 and thedrive gear 23 could be omitted and therotor 27 of theelectric motor 10 may be connected to thegear 23 directly or via a reduction gear unit.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (21)

What is claimed is:

1. A hybrid vehicle, comprising:

(a) an internal combustion engine having output at an engine shaft;

(b) a generator connected to said engine shaft, said generator including:

a first stator; and

a first rotor rotatably mounted coaxially with said first stator;

(c) an electric motor axially aligned with said engine shaft and including:

a second stator; and

a second rotor rotatably mounted coaxially with said second stator;

(d) an output gear assembly connected to an output shaft driven by said second rotor and located between said generator and said electric motor;

.[.(e) a clutch adapted to connect and disconnect said engine shaft to/from said second rotor;

(f).]. .Iadd.(e) .Iaddend.a differential gear unit driven by said output gear assembly; and

.[.(g).]. .Iadd.(f) .Iaddend.a counter shaft oriented in parallel with the output shaft, said counter shaft including gears for transmitting torque from said output gear assembly to said differential gear unit.

2. The hybrid vehicle according to claim 1, wherein said output gear assembly is provided with an automatic transmission unit after said second rotor for changing the speed of the rotation of said second rotor and for transmitting the rotation to the output shaft.

3. The hybrid vehicle according to claim 2, wherein the automatic transmission unit includes at least one planetary gear unit.

4. The hybrid vehicle according to claim 3, wherein the automatic transmission unit is arranged as an under-drive unit.

5. The hybrid vehicle according to claim 2, wherein the automatic transmission unit includes a hydraulic wet clutch.

6. The hybrid vehicle according to claim 1, wherein the engine shaft is connected with said first rotor through a damper.

7. The hybrid vehicle according to claim 1, wherein said generator includes a speed-increasing gear assembly located in its interior, for increasing the speed of rotation received from the engine shaft and for transferring the rotation at the increased speed to said first rotor.

8. The hybrid vehicle according to claim 7, wherein the speed-increasing gear assembly of said generator is a planetary gear unit.

9. The hybrid vehicle according to claim 7, wherein the engine shaft is connected with the speed-increasing gear assembly of said generator through a damper.

10. The hybrid vehicle according to claim 1, wherein the radial dimension of said output gear assembly located between said generator and said electric motor is smaller in size than corresponding dimensions of both of said generator and said electric motor.

11. The hybrid vehicle according to claim 1, wherein said generator, said electric motor and said output gear assembly are all housed together in one integral case.

12. The hybrid vehicle according to claim 11, wherein the integral case is abutted against said internal combustion engine.

13. The hybrid vehicle according to claim 12, wherein the integral case has three defined sections, the first section housing said generator, the second section housing said output gear assembly, and the third section housing said electric motor.

14. The hybrid vehicle according to claim 13, wherein said first stator is fixed to the first section of the case.

15. The hybrid vehicle according to claim 13, wherein said second stator is fixed to the third section of the case.

16. The hybrid vehicle according to claim .[.1.]. .Iadd.20.Iaddend., wherein said clutch is a hydraulic wet clutch.

17. A hybrid vehicle comprising:

drive wheels for propelling the vehicle;

a differential unit for transmitting torque to the drive wheels;

an internal combustion engine having torque output at an engine shaft;

an output gear for transmitting .Iadd.the .Iaddend.torque to said differential unit;

.[.a clutch for selectively connecting said engine shaft to said output gear;.].

a battery for storing electric power;

a generator, driven off of said engine shaft, for charging said battery;

an electric motor, powered by said battery, for transmitting torque to said output gear, said motor including a rotor;

wherein said internal combustion engine is axially aligned with, in succession, said generator.[., said clutch.]., said output gear and said electric motor.

18. The hybrid vehicle according to claim 17 wherein said engine shaft is continuously rotated at a constant speed.

19. The hybrid vehicle according to claim 17 additionally comprising:

an intermediate shaft .[.connected to said clutch.]. for receiving torque from said internal combustion engine and fixed to said rotor for receiving torque from said motor;

an output shaft coaxial with and rotatable supported by said intermediate shaft, said output shaft being fixed to said output gear; and

a transmission unit for transmitting torque from said intermediate shaft to said output shaft and for changing the speed of the transmitted torque. .Iadd.

20. The hybrid vehicle according to claim 17 further comprising a clutch for selectively connecting said engine shaft to said output gear and wherein said intermediate shaft is connected to said clutch for receiving the torque from said internal combustion through said clutch. .Iaddend..Iadd.

21. The hybrid vehicle according to claim 1 further comprising a clutch adapted to connect said engine to said second rotor and to disconnect said engine from said second rotor. .Iaddend.

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