Hybrid vehicle

Details Hybrid vehicle Hybrid vehicle

1999-12-27

2002-02-12

Marmor, Charles A. (Department: 3681)

Interrelated power delivery controls, including engine control

Plural engines

Electric engine

C477S008000, C475S005000

Reexamination Certificate

active

06346062

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid vehicle which has a continuously variable transmission using a metal belt, and which is driven by both electric energy and mechanical energy from an internal combustion engine.
This application is based on Japanese Patent Application No. 10-372046, the contents of which are incorporated herein by reference.
2. Description of the Related Art
To reduce emission of toxic substances in the air, electric vehicles have been developed. These electric vehicles, which are driven only by electric energy, have a limited driving range, depending on the capacities of batteries for storing the electric energy. To obtain a sufficient driving range, the batteries must have enormous capacities, which significantly deteriorate the driving performances. Therefore, hybrid vehicles, which use batteries with reduced size, can ensure sufficient driving range, and can improve the driving performances by driving internal combustion engines with fossil fuel while obtaining the mechanical energy and electric energy from the internal combustion engines, have been developed.
Of these hybrid vehicles, a hybrid vehicle which adds a driving/regenerating motor at a predetermined reduction ratio to the driving shaft of a conventional vehicle which has a continuously variable transmission (CVT) using a metal belt, is known. To manufacture this hybrid vehicle, an existing power plant can be utilized as is, and the weight and costs of the system and investment in the manufacturing plant and machinery can be reduced because the additional electrical parts are small.
An example of the hybrid vehicle is shown in
FIGS. 4 and 5
.
FIG. 4
is a schematic diagram showing the power train of the hybrid vehicle
1
, and
FIG. 5
is a schematic diagram showing the hydraulic circuit of the hybrid vehicle
1
.
In the power train shown in
FIG. 4
, the force from the engine (internal combustion engine) E is input via a torque converter
2
to a forward/reverse switching planetary gear set
3
. As shown in
FIG. 5
, the forward/reverse switching planetary gear set
3
selectively engages with one of frictional elements
6
and
7
, which are hydraulically actuated, by a hydraulic switching valve
5
mechanically connected to a select lever
4
, in response to the operation of a select lever
4
. Thus, the rotational direction of the force from the engine E, which is input to a driving pulley (first pulley)
9
of a CVT
8
shown in
FIG. 4
, can be switched.
Further, the rotation of the driving pulley
9
is transmitted via a metal belt
10
to a driven pulley (second pulley)
11
. The ratio of the rotational speeds of the driving pulley
9
to the driven pulley
11
depends on the wrapping diameters of the metal belt
10
around the pulleys. The wrapping diameters are controlled by pressing forces produced by the oil pressure given to side houses
12
and
13
of the pulleys. The oil pressure is produced by an oil pump (oil pressure producing mechanism)
14
which is driven by the engine E.
The force transmitted to the driven pulley
11
is further transmitted via the final reduction gear (driving force transmitting device)
15
to a drive shaft
16
, which drives driving wheels W. The final reduction gear
15
is connected via a gear
17
to the output shaft from the driving/regenerating motor M.
The driving/regenerating motor M is electrically connected to the battery and the motor controller which are not shown.
The hybrid vehicle
1
can convert the kinetic energy of the vehicle into electrical energy (regeneration) by means of the driving/regenerating motor M when the vehicle decelerates. Further, once the engine E is stopped while the vehicle is parked, the vehicle can be restarted by the driving/regenerating motor M in response to the request from the driver. When the driver demands more power, the engine E is additionally started, and the force is transmitted via the CVT
8
to the drive shaft
16
, to thereby provide sufficient driving force.
As described above, by adding electrical parts which are smaller than those of an electric vehicle to the metal belt CVT, the kinetic energy of the vehicle can be effectively collected. The engine may be stopped while the vehicle is parked, and therefore the fuel consumption can be remarkably improved.
However, although the above-mentioned hybrid vehicle
1
has improved fuel consumption, the following problems arise.
When driving only by the driving/regenerating motor M while stopping the engine E, the CVT
8
is rotated as the driving/regenerating motor M is rotated, because the output shaft of the driving/regenerating motor M is always connected to the driven pulley
11
of the CVT
8
. The force for rotating the CVT
8
becomes a burden on the driving/regenerating motor M, which causes energy loss. Further, in this situation, because the oil pump
14
is driven by the engine E, the oil pressure is not available when the engine E is stopped. Therefore, the pressing forces for rotating the metal belt
10
and the driving and driven pulleys
9
and
11
together without slippage do not act effectively, and the metal belt
10
may slip on the driving pulley
9
and on the driven pulley
11
at a relative speed. The relative slippage between the metal belt and the pulleys must be prevented under all circumstances, and if it is not prevented, their lives may be adversely affected.
Further, when starting the engine E after the starting of the vehicle by the driving/regenerating motor M, the oil pump
11
may be actuated at the same time as the starting of the engine E. When the unstable oil pressure just after the start-up of the oil pump
11
is provided to the frictional elements
6
and
7
and the side houses
12
and
13
, the driving force from the engine E may be unstably transmitted to the drive shaft
16
.
BRIEF SUMMARY OF THE INVENTION
The present invention is intended to reduce the energy loss caused by driving the vehicle by the motor while stopping the internal combustion engine, and to prevent the degradation of the continuously variable transmission using the metal belt. Further, the present invention is intended to ensure driving comfort when starting the internal combustion engine while driving the vehicle only by the motor.
According to a first embodiment of the present invention, the hybrid vehicle comprises: an internal combustion engine (i.e., an engine E in the embodiment); a continuously variable transmission (a CVT
8
in the embodiment); for transmitting a force between a first pulley (a driving pulley
9
in the embodiment) and a second pulley (a driven pulley
11
in the embodiment) through a metal belt (the metal belt
10
in the embodiment); and a motor (a driving/regenerating motor M in the embodiment), wherein an output shaft of the internal combustion engine is connected to the first pulley, the second pulley is connected to an output shaft of the motor, the output shaft of the motor is connected to a driving force transmitting device (a final reduction gear
15
in the embodiment) for transmitting a driving force from the second pulley and the motor, the motor and the driving force transmitting device are connected to the second pulley via an engaging element (a clutch
22
in the embodiment) for selectively connecting or disconnecting the transmission of the driving force to the second pulley, and the engaging element disconnects the transmission of the force when the internal combustion engine is stopped.
The hybrid vehicle does not transmit the driving force from the motor to the continuously variable transmission when driving the vehicle only by the motor. Thus, the continuously variable transmission does not become a load on the motor.
According to a second invention, the hybrid vehicle of the first invention, the continuously variable transmission presses the metal belt onto the first pulley and onto the second pulley by oil pressure from an oil pressure producing mechanism (an oil pump
14
in the embodiment) which is driven by the internal combus

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