Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Electric vehicle
Reexamination Certificate
2000-05-16
2002-03-12
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Electric vehicle
C290S04000F, C290S04000F, C290S04000F, C290S04000F, C180S193000
Reexamination Certificate
active
06356817
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 11-136549 filed on May 18, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power output unit, a method of controlling the power output unit, and a hybrid vehicle. More particularly, the present invention relates to a power output unit which has an internal combustion engine and motor-generators and in which an output shaft of the internal combustion engine, rotational shafts of the motor-generators and a drive shaft are mechanically connected to one another, a method of controlling the power output unit, and a hybrid vehicle.
2. Description of the Related Art
In recent years, various constructions have been proposed for a hybrid vehicle having motor-generators in addition to an internal combustion engine. A hybrid vehicle makes it possible to significantly reduce an amount of consumption of fossil fuel in comparison with a vehicle having a gasoline engine. As environmental problems become acute, social demands for hybrid vehicles grow. A parallel hybrid vehicle is one of such hybrid vehicles. In a parallel hybrid vehicle, both a power from an internal combustion engine and a power from an electric motor can be transmitted to a vehicle axle.
FIG. 1
shows an example of the structure of a parallel hybrid vehicle. The hybrid vehicle shown in
FIG. 1
has an engine
150
and motor-generators MG
1
, MG
2
. These three components are mechanically coupled to one another through a planetary gear
120
. The planetary gear
120
is composed of three gears and has three rotational shafts respectively coupled to the gears. The gears constituting the planetary gear
120
are a sun gear
121
which rotates at the center, a planetary pinion gear
123
which rotates around the sun gear
121
while auto rotating, and a ring gear
122
which rotates around the planetary pinion gear
123
. The planetary pinion gear
123
is pivoted on a planetary carrier
124
. In the hybrid vehicle shown in
FIG. 1
, a crank shaft
156
serving as a drive shaft of the engine
150
is coupled to a rotational shaft of the planetary carrier
124
, thus constituting a planetary carrier shaft
127
. A drive shaft of the motor-generator MG
1
is coupled to a rotational shaft of the sun gear
121
, thus constituting a sun gear shaft
125
. A drive shaft of the motor-generator MG
2
is coupled to a rotational shaft of the ring gear
122
, thus constituting a ring gear shaft
126
. Furthermore, the ring gear
122
is coupled to a vehicle axle
112
through a chain belt
129
and a differential gear.
For the purpose of explaining the basic operation of a hybrid vehicle having such a construction, operation of the planetary gear
120
will first of all be described. In the planetary gear
120
, if rotational speeds of two of the three rotational shafts and a torque of one of the three rotational shafts (hereinafter a rotational speed and a torque of a certain rotational shaft will comprehensively be referred to as a rotational state) are determined, rotational states of all the rotational shafts are determined. Although a relation among rotational states of the rotational shafts can be found out using a calculation formula which is well known to the community of mechanics, it can also be found out geometrically by means of an alignment chart.
FIG. 2
shows an alignment chart as an example. While the axis of ordinate shows rotational speeds of the rotational shafts, the axis of abscissa shows a relation in distance among gear ratios of the gears. A position C, which is an interior division point of 1: &rgr; between the sun gear shaft
125
(S in
FIG. 2
) and the ring gear shaft
126
(R in FIG.
2
), is defined as a position of the planetary carrier shaft
127
. The value of &rgr; represents a ratio (Zs/Zr) of the number of teeth of the sun gear
121
(Zs) to the number of teeth of the ring gear
122
(Zr). For the points S, C and R defined along the axis of abscissa, rotational speeds Ng, Ne and Nm of the rotational shafts are plotted respectively. According to the feature of the planetary gear
120
, the three points that have thus been plotted never fail to be aligned along a single line. This line is referred to as an operation co-line. A line is uniquely determined if two points are specified. Thus, reference to this operation co-line makes it possible to calculate a rotational speed of one of the three rotational shafts from rotational speeds of the remaining two rotational shafts.
According to the feature of the planetary gear
120
, when torque values of the rotational shafts are replaced with forces acting on the operation co-line, the operation co-line maintains its balance as a rigid body. As a concrete example, a torque acting on the planetary carrier shaft
127
is defined as Te. In this case, as shown in
FIG. 2
, a force corresponding to the torque Te is applied upwards to the operation co-line at the position C. A direction of application of the force is determined in accordance with a direction of the torque Te. Also, a torque Tp acting on the ring gear shaft
126
is applied downwards to the operation co-line at the position R. Tes and Tep shown in
FIG. 2
are two equivalent forces obtained as a result of distribution of the torque Te according to the law of distribution of forces acting on a rigid body. The torque values Tes, Tep can be expressed by the following formulas (1) and (2).
Tes=&rgr;/(1+&rgr;)×Te (1)
Tep=1/(
1+&rgr;)×Te
(2)
In consideration of a condition that the operation co-line is balanced as a rigid body during application of those forces, it is possible to calculate a torque Tg to be applied to the sun gear shaft
125
by the motor-generator MG
1
and a torque Tm to be applied to the ring gear shaft by the motor-generator MG
2
. The torque Tg becomes equal to the torque Tes, and the torque Tm becomes equal to a difference between the torque Tp and the torque Tep. The torque values Tg, Tm having such features are expressed by the following formulas (3) and (4) respectively.
Tg=−&rgr;/(1+&rgr;)×Te (3)
Tm=Tp−1/(1+&rgr;)×Te (4)
While the engine
150
coupled to the planetary carrier shaft
127
rotates, the sun gear
121
and the ring gear
122
can rotate in various operation states with the aforementioned conditions on the operation co-line being satisfied. When the sun gear
121
rotates, it is possible to generate electricity in the motor-generator MG
1
by means of a rotational power of the sun gear
121
. When the ring gear
122
rotates, it is possible to transmit a power outputted from the engine
150
to the vehicle axle
112
. In a hybrid vehicle having a construction shown in
FIG. 1
, a power outputted from the engine
150
is divided into a power that is mechanically transmitted to the vehicle axle
112
and a power that is converted into electric power through regeneration of one of the motor-generators MG
1
, MG
2
(operating as a generator). Furthermore, the electric power that has been regenerated is used for power running of the other motor-generator (operating as an electric motor), whereby the vehicle can travel with a desired power outputted to the vehicle axle
112
. Thus, when the hybrid vehicle constructed as shown in
FIG. 1
travels, the motor-generators MG
1
, MG
2
usually perform power running or regeneration. In this case, control is performed such that the electric power consumed during power running is balanced against the electric power generated during regeneration.
In the hybrid vehicle constructed as shown in
FIG. 1
, when controlling a travelling state of the vehicle, a torque requirement for the vehicle axle
112
(actually the ring gear shaft
126
mechanically coupled to the vehicle axle) is first of all determined from a vehicle speed and an accelerator opening degree. A power requirement to b
Cuchlinski Jr. William A.
Kenyon & Kenyon
Marc-Coleman Marthe
Toyota Jidosha & Kabushiki Kaisha
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