Prime-mover dynamo plants – Electric control – Starting and generating dynamo
Reexamination Certificate
2000-10-23
2003-04-29
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Electric control
Starting and generating dynamo
C290S04000F
Reexamination Certificate
active
06555927
ABSTRACT:
The disclosure of Japanese Patent Application No. 11-329891 filed on Nov. 19, 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 invention relates to vehicular engine starting control apparatus and vehicular engine starting control methods for a vehicle having an engine and a motor generator as power sources.
2. Description of Related Art
Hybrid vehicles having an engine and a motor generator as power sources for driving the vehicle are known. For example, as disclosed in Japanese Laid-Open Patent Application No 9-170533 (which corresponds to U.S. Pat. No. 5,934,395), some vehicles of this type have an engine started by means of a motor generator and others have an engine started by a separate starter (a dedicated motor for starting the engine).
A hybrid vehicle performs an iterative operation of automatically stopping and restarting the engine (hereinafter referred to as “intermittent operation” for convenience of explanation). Thus, the engine is either started through operation by the vehicle driver (started by switching an ignition key from OFF to ON) or automatically restarted during intermittent operation. However, in the aforementioned vehicles, a suitable selection in terms of the characteristics of the starter and the motor generator has not always been made.
SUMMARY OF THE INVENTION
It is one object of the invention to provide a vehicular engine starting control apparatus for a vehicle equipped with both a starter and a motor generator wherein startability of the engine can be improved by starting the engine while suitably selecting between the starter and the motor generator.
In order to solve the aforementioned and/or other problems, according to a first aspect of the invention there is provided a vehicular engine starting control apparatus for a vehicle having an engine which outputs power to a drive shaft of the vehicle, a motor generator which inputs power to and outputs power from a power transmission path that extends from an output shaft the engine to the drive shaft, and a starter which is coupled to the output shaft of the engine. The vehicular starting control apparatus includes a controller that: (1) receives an initial engine starting command if an ignition key has been switched from OFF to ON; (2) receives an engine restarting command upon fulfillment of a predetermined restarting condition during automatic stop of the engine; (3) issues a command to start the engine by using the starter upon issuance of the initial engine starting command; and (4) issues a command to start the engine by using the motor generator upon issuance of the engine restarting command.
In general, the starter and the motor generator are intrinsically different in function. Although they are both electric motors, they are different in type and performance.
The starter (ST) can reliably start the engine under any circumstance (e.g., even in a frigid state). The starter is usually constructed of a DC motor and driven at a low speed and a large torque with a low voltage and large electric power. Thus, since the starter is capable of generating a large torque, the engine can be started reliably even at a low temperature. On the other hand, the starter has disadvantages such as large power consumption, inadequate responsive characteristics and strong oscillation.
The motor generator (MG) is used as an electric motor to assist or replace the engine when driving the vehicle, and is used as a generator to regenerate coasting energy during deceleration (which is used to charge a battery that supplies energy to the motor generator when it is used as an electric motor). Thus, because of mechanical characteristics of the motor generator, the torque that can be generated thereby is smaller in comparison with the starter. The motor generator is driven at a high speed and a low torque with a high voltage and small electric power. Thus, even when the engine is repeatedly stopped and automatically restarted irrespective of the driver's intention as in the case of intermittent operation, the motor generator makes it possible to start the engine without causing a sense of incongruity to the driver. However, the motor generator cannot generate a large torque and is thus unsuited for the starting operation at a low temperature, for example. Especially in a frigid state where the battery itself cannot function properly, the motor generator is disadvantageous in that it causes further deterioration of startability.
In the first aspect of the invention, the engine starting operation that is performed when the driver switches the ignition ON and the engine restarting operation that is automatically performed during intermittent operation are distinguished from each other. If the ignition key has been switched from OFF to ON, the engine is started by the starter. On the other hand, the engine is restarted by the motor generator while the vehicle is being driven (i.e., restarted during intermittent operation).
In many cases, the engine is initially started by switching the ignition key ON when the temperature is low. Because this operation is performed by the starter, the engine starting operation can be performed with high reliability. Because this starting operation is based on the driver's intention, oscillation or noise can be tolerated to some extent. Such oscillation or noise sometimes helps the driver confirm that the engine definitely has been started. Further, since the engine is restarted by means of the motor generator during intermittent operation, the engine restarting operation can be performed tranquilly and smoothly (without causing a sense of incongruity to the driver). Therefore, it is possible to sufficiently exploit advantages of using the starter and the motor generator while counterbalancing their disadvantages.
According to a second aspect of the invention, there is provided a vehicular engine starting control apparatus for a vehicle having an engine which outputs power to a drive shaft of the vehicle, a motor generator which inputs power to and outputs power from a power transmission path that extends from an output shaft of the engine to the drive shaft, and a starter which is coupled to the output shaft of the engine. The vehicular engine starting control apparatus includes a temperature detector which detects a temperature of the engine, and a controller which: (1) issues a command to start the engine with the starter if the detected temperature of the engine is equal to or lower than a predetermined temperature; and (2) issues a command to start the engine with the motor generator if the detected temperature of the engine is higher than the predetermined temperature.
In the second aspect of the invention, it is determined whether the engine is to be started with the starter or with the motor generator depending on a detected temperature of the engine. That is, since the engine cannot be started smoothly when the temperature of the engine is low, the engine is started with the starter. Thus, while sacrificing tranquility to some extent, startability of the engine is ensured with high reliability. On the other hand, since the engine can be started smoothly when the temperature of the engine is high, the engine is started with the motor generator. Thus, startability of the engine is ensured with tranquility, smoothness and good responsive characteristics.
In the case of the second aspect of the invention, when starting the engine, the starter or the motor generator is selected depending on a temperature of the engine, without regard to whether the engine is started through operation of the ignition key or the engine is restarted during intermittent operation. This aspect of the invention is especially useful when the engine is started during intermittent operation. That is, when the engine is started during intermittent operation, use of the motor generator usually causes no problem. For example, if the vehicle has been stationary for a long time in a cold
Okada Daimon
Suzuki Naoto
Suzuki Takashi
Takaoka Toshifumi
Ponomarenko Nicholas
Toyota Jidosha & Kabushiki Kaisha
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