U.S. patent application number 09/749685 was filed with the patent office on 2001-08-23 for transmission for hybrid electric vehicle.
Invention is credited to Jung, Hu-Yong.
Application Number | 20010016532 09/749685 |
Document ID | / |
Family ID | 19631018 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016532 |
Kind Code |
A1 |
Jung, Hu-Yong |
August 23, 2001 |
Transmission for hybrid electric vehicle
Abstract
To improve acceleration performance on starting and in low speed
ranges as well as minimizing energy loss with its simple structure
of light weight and small size, a transmission for a hybrid
electric vehicle includes a first motor connected to a battery
through an inverter, the first motor functioning as a generator, a
differential disposed between an engine and the first motor to
provide driving force from one of the first motor and the engine, a
final reduction gear engaged with the differential to transmit
drive force to wheels, a second motor connected to the battery
through the inverter to directly drive an axle shaft, a first
one-way clutch disposed between the differential and the engine,
and a second one-way clutch disposed within the differential.
Inventors: |
Jung, Hu-Yong;
(Kwacheon-city, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
19631018 |
Appl. No.: |
09/749685 |
Filed: |
December 28, 2000 |
Current U.S.
Class: |
475/5 ;
180/65.235; 180/65.285; 475/9; 903/903; 903/905; 903/906; 903/909;
903/913; 903/951 |
Current CPC
Class: |
Y10S 903/906 20130101;
Y10S 903/909 20130101; Y10S 903/913 20130101; F16H 2037/0866
20130101; B60K 1/02 20130101; B60K 6/445 20130101; Y10S 903/905
20130101; F16H 48/06 20130101; Y02T 10/62 20130101; Y10S 903/951
20130101; B60W 10/26 20130101; B60W 10/08 20130101; B60K 6/383
20130101; Y10S 903/903 20130101 |
Class at
Publication: |
475/5 ;
475/9 |
International
Class: |
B60K 006/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 1999 |
KR |
99-63696 |
Claims
What is claimed is:
1. A transmission for a hybrid electric vehicle comprising: a first
motor connected to a battery through an inverter, the first motor
functioning as a generator; a differential disposed between an
engine and the first motor to provide driving force from one of the
first motor and the engine; a final reduction gear engaged with the
differential to transmit drive force to wheels; a second motor
connected to the battery through the inverter to directly drive an
axle shaft; a first one-way clutch disposed between the
differential and the engine; and a second one-way clutch disposed
within the differential.
2. The transmission of claim 1 wherein the differential comprises a
first drive pinion connected to the engine by the first one-way
clutch, a second drive pinion having a first end connected to the
first drive pinion by the second one-way clutch and a second end
connected to the first motor, first and second driven pinions
driven by the first and second drive pinions, respectively, and a
carrier engaged with the first and second driven pinions to
transmit power of the first and second drive pinions to the final
reduction gear.
3. The transmission of claim 2 wherein the first one way clutch is
designed to transmit clockwise rotational force from the engine to
the first drive pinion, and the second one-way clutch is designed
to transmit clockwise rotational force from the second drive pinion
to the first drive pinion.
Description
BACKGROUND OF THE INVENTION
[0001] (a) Field of the Invention
[0002] The present invention relates to a transmission for a hybrid
electric vehicle (HEV) having a high acceleration performance on
start and in low speed ranges as well as having a simple structure
of light-weight and small-size, resulting in minimizing energy
loss.
[0003] (b) Description of the Related Art
[0004] Hybrid electric vehicles (HEVs) were conceived as a way to
compensate for the shortfall in battery technology of an electric
vehicle. So, HEVs combine the internal combustion engine of a
conventional vehicle with the battery and electric motor of an
electric vehicle.
[0005] Typically, the HEVs are classified into series, parallel,
and split types according to a power transmission structure.
[0006] The series type HEV uses an engine just as a generator for
generating electricity for a battery pack so as to overcome the
drawback of the electric vehicle having a short driving distance.
That is, the driving force of the series type HEV comes entirely
from the electric motor as in a purely electric vehicle. The series
type HEV has a disadvantage in that a power loss occurs during an
electricity/power conversion and an AC/DC conversion. However, the
engine never idles, which reduces vehicle emissions.
[0007] The parallel type HEV has a direct mechanical connection
between the engine and the wheels as in a conventional vehicle, but
also has an electric motor that drives the wheels so as to provide
extra power to the driveline when power assist is needed for
climbing on a slope or for quick acceleration.
[0008] The split type HEV is a compromise type having advantages of
both the series and parallel type systems for optimizing energy
efficiency. FIG. 2 schematically shows a split type HEV.
[0009] The split type HEV comprises a battery 112, an inverter 114
for inverting DC (direct current) from the battery 112 into AC
(alternating current), a motor 116 for converting electrical energy
from the inverter 114 into mechanical energy, a planetary gear set
120 acting as a mechanical energy distributor, and a final
reduction gear 124 for transferring the driving torque to
wheels.
[0010] The planetary gear set 120 includes a sun gear 128, a ring
gear 130 connected to the final reduction gear 124, and a few
pinion gears 132 connected by a carrier 134 and circumferentially
interposed between the sun gear 128 and the ring gear.
[0011] In the split type HEV, the electric motor supplies power
when the vehicle is starting and running at a low speed, and it can
easily reverse the vehicle by changing a rotation direction of the
motor 116. The vehicle uses the power created from the engine in a
normal driving state and the motor acts as a generator for
regenerating the battery during the engine operation. The motor can
also provide extra power to the wheels when a power assist is
needed for quick acceleration.
[0012] The series and parallel type HEVs use continuously variable
transmissions (CVTs), and the adoption of the CVT increases the
vehicle's weight and causes energy loss through generating
hydraulic pressure.
[0013] In the split type HEV, a planetary gear set interposed
between the engine and the motor causes an increase in both the
vehicle's weight and manufacturing costs.
SUMMARY OF THE INVENTION
[0014] The present invention has been made in an effort to solve
the above problems of the prior art.
[0015] It is an object of the present invention to provide a
transmission for a HEV capable of improving acceleration
performance on starting and in low speed ranges as well as
minimizing energy loss with its simple structure of light weight
and small size.
[0016] To achieve the above object, the present invention provides
a transmission for a hybrid electric vehicle comprising a first
motor connected to a battery through an inverter, the first motor
functioning as a generator, a differential disposed between an
engine and the first motor to provide driving force from one of the
first motor and the engine, a final reduction gear engaged with the
differential to transmit drive force to wheels, a second motor
connected to the battery through the inverter to directly drive an
axle shaft, a first one-way clutch disposed between the
differential and the engine, and a second one-way clutch disposed
within the differential.
[0017] Preferably, the differential comprises a first drive pinion
connected to the engine by the first one-way clutch, a second drive
pinion having a first end connected to the first drive pinion by
the second one-way clutch and a second end connected to the first
motor, first and second driven pinions driven by the first and
second drive pinions, respectively, and a carrier engaged with the
first and second driven pinions to transmit power of the first and
second drive pinions to the final reduction gear.
[0018] Preferably, the first one way clutch is designed to transmit
clockwise rotational force from the engine to the first drive
pinion, and the second one-way clutch is designed to transmit
clockwise rotational force from the second drive pinion to the
first drive pinion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate an embodiment of
the invention, and, together with the description, serve to explain
the principles of the invention, wherein:
[0020] FIG. 1 is a simplified block diagram of an HEV equipped with
a transmission according to a preferred embodiment of the present
invention; and
[0021] FIG. 2 is a simplified block diagram of an HEV equipped with
a prior art transmission.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] A preferred embodiment of the present invention will be
described hereinafter with reference to the accompanying
drawings.
[0023] In FIG. 1, an HEV comprises a battery 12, an inverter 14 for
inverting direct current (DC) of the battery 12 into alternating
current (AC), two motors 16 and 18 and a combustion engine 20 for
providing driving torque, a final reduction gear 24 engaged with a
differential, and first and second one-way clutches 26 and 28.
[0024] The battery 12 is preferably one of a Ni--MH battery and a
Li-ion battery that is widely used for the HEV.
[0025] The motors 16 and 18 convert electric energy of the battery
into mechanical energy to drive the differential 22 and the axle
shaft 30, respectively. The motors 16 and 18 also function as
generators that convert mechanical energy generated during the
shifting and braking operations into electric energy to recharge
the battery.
[0026] To drive the final reduction gear 24 by coupling power from
both the engine 20 and the first motor 16, a power coupling manner
is used in this embodiment. That is, the differential 22 is
disposed between the first motor 16 and the engine 20, and the
one-way clutch 26 is disposed between the differential 22 and the
engine 20. The one-way clutch 28 is disposed in the differential
22.
[0027] Describing more in detail, the differential 22 includes a
first drive pinion 32 connected to the engine 20 by the one-way
clutch 26, a second drive pinion 34 having a first end connected to
the first drive pinion 32 by the one-way clutch 28 and a second end
connected to the first motor 16, first and second driven pinions 36
and 38 driven by the first and second drive pinions 32 and 34, and
a carrier 40 engaged with the driven pinions 36 and 38 to transmit
power of the first and second drive pinions 32 and 34 to the final
reduction gear 24.
[0028] The one-way clutch 26 is designed to transmit clockwise
power from the engine 20 to the first drive pinion 32, and the
one-way clutch 28 is designed to transmit clockwise power from the
second drive pinion 34 to the first drive pinion 32.
[0029] Accordingly, when the vehicle is accelerated, since the
second drive pinion 34 rotates clockwise by the first motor 16, the
rotational power is transmitted only to the first drive pinion 32
but not to the engine. In a normal operation of the vehicle, since
the power transmission shaft (i.e., crankshaft) of the engine
rotates clockwise, the rotational power of the power transmission
shaft is transmitted only to the first drive pinion 32 but not to
the second drive pinion 34 and the first motor 16. During the
normal operation of the vehicle, the rotation of the first motor 16
is controlled in connection with the rotations of the engine and
the second motor.
[0030] The power transmission of the above described power
transmission system will be described hereinafter.
[0031] First, when the vehicle starts or runs at a low speed, only
the first and second motors 16 and 18 are driven by the battery.
That is, the first motor 16 drives the differential 22, and the
second motor 18 drives the axle shaft 30. Accordingly, the vehicle
speed depends on a control logic associated with the first and
second motors. At this point, the driving force through the first
motor 16 is transmitted to the first drive pinion 32 synchronized
with the second drive pinion 34 by the second one-way clutch 28.
Here, the engine 20 operation is initiated by a starter motor.
[0032] When the vehicle is accelerated above a predetermined speed
such that the rotational number becomes higher than that of the
first motor 16, the differential 22 is driven by the engine 20,
while the axle shaft 30 is continuously driven by the second motor
18, Here, the first motor 16 is rotatable in both directions
(forward and reverse directions) according to the rotational
numbers of the engine 20 and the second motor 18. When the first
motor 16 rotates in the reverse direction, this functions as a
generator for recharging the battery.
[0033] When braking force is applied to the vehicle, since the
revival braking force is generated on the second motor 18, the
second motor 18 functions as a generator.
[0034] Since the above described HEV is designed to transmit power
using a differential and a one-way clutch, the structure thereof is
simpler than a conventional one employing a continuously variable
transmission and a planetary gear unit to transmit power.
Accordingly, the HEV according to the present invention is capable
of improving acceleration performance on starting and in low speed
ranges as well as minimizing energy loss with its simple structure
of light weight and small size.
[0035] Although preferred embodiments of the present invention have
been described in detail hereinabove, it should be clearly
understood that many variations and/or modifications of the basic
inventive concepts herein taught which may appear to those skilled
in the present art will still fall within the spirit and scope of
the present invention, as defined in the appended claims.
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