Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
2000-10-10
2003-12-02
Bonck, Rodney H. (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
C180S065230
Reexamination Certificate
active
06656082
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid vehicle having both an engine and a motor as power sources, and more specifically to a hybrid vehicle having a changeover mechanism that changes connection of the motor between a drive shaft linked with the wheels and an output shaft of the engine.
2. Description of the Related Art
A parallel hybrid vehicle is one type of the hybrid vehicles having both an engine and a motor as power sources. The parallel hybrid vehicle has a power regulation unit linked with the engine. Part of the power output from the engine is transmitted to a drive shaft linked with the wheels via the power regulation unit, while the residual power is regenerated as electric power. The regenerative electric power is accumulated in a battery or is used to drive the motor, which is used as the power source. The parallel hybrid vehicle controls the power regulation unit and the motor, so as to arbitrarily convert the revolving speed and the torque output from the engine to those suitable for the drive shaft. The hybrid vehicle selects a desirable driving point of the engine having a high driving efficiency and drives the engine at that point, irrespective of the revolving speed and the torque of the drive shaft, thus ensuring excellent resource saving effects and less emission.
In the parallel hybrid vehicle, the motor may be linked with either the drive shaft or the output shaft of the engine. When the motor is connected with the drive shaft, the engine, the power regulation unit, and the motor are linked in this order.
FIG. 30
schematically illustrates the structure of a hybrid vehicle having a motor linked with a drive shaft. In the example of
FIG. 30
, a pair-rotor motor CM having an inner rotor IR and an outer rotor OR that are rotatable relative to each other is used as the power regulation unit. As illustrated in
FIG. 30
, the pair-rotor motor CM is connected to an output shaft CS of an engine EG, whereas an assist motor AM is linked with a drive shaft DS. This structure ensures the high driving efficiency in the state of underdrive when the revolving speed of the drive shaft DS is lower than that of the engine EG. This structure is called “underdrive connection” in this specification.
FIG. 31
shows power transmission in the underdrive connection when the revolving speed of the engine EG is higher than that of the drive shaft DS. The power output from the engine EG is reduced in revolving speed and enhanced in torque to be output from the drive shaft DS. The pair-rotor motor CM transmits a power PU
1
output from the engine EG as a power PU
2
of the reduced revolving speed. A slip occurs between two rotors in the pair-rotor motor CM, so that electric power is generated based on the slip. Part of the power PU
1
is accordingly regenerated as an electric power EU
1
. The assist motor AM is driven with this regenerative electric power to increase the torque of the drive shaft DS. This generates a power PU
3
corresponding to the required revolving speed and torque of the drive shaft DS.
FIG. 32
shows power transmission in the underdrive connection when the revolving speed of the engine EG is lower than that of the drive shaft DS. The pair-rotor motor CM carries out the power running to transmit the power PU
1
output from the engine EG as a power PU
4
of the raised revolving speed. The assist motor AM acts as a load to reduce its excess torque, thereby outputting the power PU
3
corresponding to the required revolving speed and torque of the drive shaft DS. The assist motor AM regenerates part of the mechanical power PU
4
as an electric power EU
2
, so as to apply the loading. This regenerative electric power is used for the power running of the pair-rotor motor CM.
In the case where the revolving speed of the engine EG is higher than that of the drive shaft DS (in the case of FIG.
31
), the electric power regenerated by the pair-rotor motor CM located on the upstream side is supplied to the assist motor AM located on the downstream side in a path along which the power output from the engine EG is transmitted to the drive shaft DS. In the case where the revolving speed of the engine EG is lower than that of the drive shaft DS (in the case of FIG.
32
), on the other hand, the electric power regenerated by the assist motor AM located on the downstream side is supplied to the pair-rotor motor CM located on the upstream side. The electric power supplied to the pair-rotor motor CM is subsequently supplied to the assist motor AM located on the downstream side as a mechanical power. This results in a circulation of power &ggr;
1
as shown in FIG.
32
. The circulation of power &ggr;
1
reduces the effective power transmitted to the drive shaft DS out of the power output from the engine EG, thus lowering the driving efficiency of the hybrid vehicle.
When the motor is connected with the output shaft of the engine, on the other hand, the engine, the motor, and the power regulation unit are linked in this order.
FIG. 33
schematically illustrates the structure of the hybrid vehicle having the motor linked with the output shaft of the engine. In the example of
FIG. 33
, the assist motor AM is linked with the output shaft CS of the engine EG, whereas the pair-rotor motor CM functioning as the power regulation unit is connected with the drive shaft DS. This structure ensures the high driving efficiency in the state of overdrive when the revolving speed of the drive shaft DS is higher than the revolving speed of the engine EG. This structure is called “overdrive connection” in this specification.
FIG. 34
shows power transmission in the overdrive connection when the revolving speed of the engine EG is higher than that of the drive shaft DS.
FIG. 35
shows power transmission in the overdrive connection when the revolving speed of the engine EG is lower than that of the drive shaft DS. Only the pair-rotor motor CM is capable of regulating the revolving speed of the transmitted power. The phenomena occurring in the overdrive connection are just opposite to those occurring in the underdrive connection. In the case where the revolving speed of the engine EG is higher than that of the drive shaft DS (in the case of FIG.
34
), an electric power EO
1
regenerated by the pair-rotor motor CM located on the downstream side is supplied to the assist motor AM located on the upstream side. In the case where the revolving speed of the engine EG is lower than that of the drive shaft DS (in the case of FIG.
35
), on the other hand, an electric power EO
2
regenerated by the assist motor AM located on the upstream side is supplied to the pair-rotor motor CM located on the downstream side. In the structure that the motor is linked with the output shaft of the engine, a circulation of power &ggr;
2
occurs in the case of FIG.
34
. This lowers the driving efficiency of the hybrid vehicle.
In the hybrid vehicle, a high efficiency driving area defined by the vehicle speed and the output torque depends upon the connection of the assist motor AM. One proposed technique changes the connection of the assist motor AM between the engine and the drive shaft, in order to improve the driving efficiency of the hybrid vehicle over a wide range.
A diversity of problems, however, arise in the process of changing the connection of the assist motor AM. A concrete example of the changeover mechanism is described here.
FIG. 36
illustrates the structure of a hybrid vehicle in which the connection of the assist motor AM is changeable. The connection of the assist motor AM is changed by means of a synchronized gear unit including three gears SG
1
, SG
2
, and SG
3
. A rotor of the assist motor AM is linked with the gear SG
3
that is slidable in the direction of the arrow. The gears SG
1
and SG
2
are respectively connected to the rotating shafts of the clutch motor CM and the engine EG. Sliding the gear SG
3
as shown by the arrow enables the connection of the assist motor AM to be changed.
The synchronized gear unit requires a certain space, in
Nagamatsu Shigetaka
Yamada Yoshinori
Bonck Rodney H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pang Roger
Toyota Jidosha & Kabushiki Kaisha
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