JP2004027844A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle capable of reducing noises when shifting from an EV drive mode to an engine drive mode. <P>SOLUTION: The hybrid vehicle 1 has an EV drive mode in which it operates only on the power of a motor 3, and an engine drive mode in which it operates while driving at least an engine 2. The EV vehicle has a controller 6 which in the EV drive mode controls the rpm of the engine 2 to be not more than desired restart rpm and which downshifts an automatic transmission to set the engine 2 at rpm higher than the desired restart rpm if the engine rpm is not higher than the desired restart rpm during shift from the EV drive mode to the engine drive mode, thereby starting fuel injection and controlling the motor 3 to raise the rpm of the engine 2 so that it is higher than engine-drive-mode desired rpm for the engine drive mode. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hybrid vehicle having an EV traveling mode in which an engine and a motor are used as driving sources and traveling using only the power of the motor, and an engine traveling mode in which at least the engine is driven to travel.
[0002]
[Prior art]
In recent years, a hybrid vehicle including an engine and a motor as a driving source of the vehicle has been proposed. As this type of hybrid vehicle, for example, as disclosed in JP-A-7-67208, a driving mode using only a motor as a power source, a driving mode using only an engine as a power source, a motor and an engine Some have a plurality of traveling modes such as a traveling mode using both of them as power sources. When the hybrid vehicle travels, a traveling mode is appropriately selected from these traveling modes, and the traveling mode is appropriately switched according to traveling conditions and the like.
[0003]
[Problems to be solved by the invention]
By the way, in order to prevent the occurrence of a shock caused by simultaneously performing the switching of the traveling mode and the change of the gear ratio of the automatic transmission, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 10-2241, the switching process of the traveling mode is performed. And a technique for shifting the gear ratio changing process.
[0004]
However, a running mode in which the vehicle runs only with the power of the motor (hereinafter, referred to as “EV running mode”) is changed to a running mode in which at least the engine is driven to run (hereinafter, referred to as “engine running mode (or ENG running mode)”). When shifting, if the engine is not provided with a sufficient number of revolutions, noise may be generated at the time of shifting to the running mode, and the above-described conventional technology cannot solve the problem.
[0005]
Further, in the EV running mode in which the vehicle runs only with the power of the motor, it is desirable to suppress the engine speed as much as possible. However, when shifting from the engine running mode to the EV running mode, the engine speed becomes higher than necessary due to inertia and the like. In some cases, the load on the motor increases, which is an obstacle to improving fuel efficiency.
[0006]
The present invention has been made in view of such circumstances, and suppresses generation of noise when shifting from the EV driving mode in which the vehicle runs only with the power of the motor to the engine driving mode in which at least the engine is driven to run. It is an object of the present invention to provide a hybrid vehicle capable of performing the above.
[0007]
It is another object of the present invention to provide a hybrid vehicle that can prevent the engine from rotating more than necessary during EV running and can improve fuel efficiency.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1 uses an engine (for example, an engine 2 in an embodiment described later) and a motor (for example, a motor 3 in an embodiment described later) as drive sources, An automatic transmission (for example, an automatic transmission 4 in an embodiment to be described later) that transmits power from the driving source to wheels (for example, a wheel 5 in an embodiment to be described later) is provided. A hybrid vehicle (for example, a hybrid vehicle 1 in an embodiment described later) including an EV traveling mode that performs an EV traveling mode and an engine traveling mode that travels while driving the engine. The engine is controlled at a rotational speed equal to or lower than the target rotational speed, and an error is generated when shifting from the EV traveling mode to the engine traveling mode. When the rotation speed of the gin is equal to or less than the restart target rotation speed (for example, step S16 in the embodiment described later), the automatic transmission is controlled to increase the engine rotation speed above the restart target rotation speed. The fuel injection is started at a rotational speed (for example, step S18 in an embodiment described later) (for example, step S20 in an embodiment described later), and the rotational speed of the engine is shifted to the engine running mode by the motor. A hybrid vehicle including a control unit (for example, a control device 6 according to an embodiment described later) for controlling the rotation speed to be higher than a target rotation speed in an engine running mode.
[0009]
According to this invention, when shifting from the EV running mode to the engine running mode, if the engine speed is equal to or less than the restart target speed, the engine speed is set higher than the restart target speed. Since the automatic transmission is controlled to be at the rotation speed, the rotation speed of the engine can be reliably set to be higher than the restart target rotation speed. The fluctuation can be suppressed within a certain range. Accordingly, noise generated due to torque fluctuation when shifting from the EV running mode to the engine running mode can be suppressed, and drivability is improved. Emissions can also be reduced by increasing the engine speed.
Further, in the EV running mode, the engine is controlled at a rotation speed equal to or lower than the target restart rotation speed, thereby improving fuel efficiency.
[0010]
The invention described in claim 2 is the invention according to claim 1, wherein when the engine speed is equal to or less than the restart target speed, the automatic transmission causes the automatic transmission to exceed the restart target speed. The hybrid vehicle is characterized by continuously controlling the number of revolutions such that
According to the present invention, the rotation speed of the engine can be set higher than the target rotation speed in a shorter time, and the transition of the driving mode can be performed more smoothly.
[0011]
According to a third aspect of the present invention, there is provided an EV traveling mode in which an engine and a motor are used as driving sources, an automatic transmission that transmits power from the driving source to wheels, and the vehicle runs only with the power of the motor. A hybrid vehicle having an engine running mode in which the engine is driven by driving the engine. When the engine running mode is shifted from the engine running mode to the EV running mode, the engine speed is higher than a target restart speed (for example, as described later). In step S36 in the embodiment, the automatic transmission is controlled to reduce the engine speed to a value equal to or lower than the restart target speed (for example, step S38 in an embodiment described later). Injection is stopped (for example, step S40 in an embodiment described later), and the vehicle shifts to the EV running mode at the restart target rotation speed or less. Control means (e.g., the control device 6 in the embodiment described below) that controls the so that a hybrid vehicle comprising: a.
[0012]
According to the present invention, when shifting from the engine running mode to the EV running mode, the automatic transmission is controlled so that the engine speed is equal to or lower than the restart target speed. The number of rotations can be reliably set to be equal to or less than the target rotation speed for restart. For this reason, at the time of the transition to the EV running, the number of revolutions of the engine can be suppressed sufficiently low, the driving force required for the motor can be reduced correspondingly, and the fuel efficiency can be improved.
[0013]
The invention described in claim 4 is the invention described in claim 3, wherein when the engine speed is higher than the restart target speed, the automatic transmission uses the restart target speed. A hybrid vehicle characterized by continuously controlling the number of revolutions as follows.
[0014]
According to the present invention, the rotation speed of the engine can be made to reach the target rotation speed in a shorter time, and the transition of the running mode can be performed more smoothly.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a hybrid vehicle 1 according to an embodiment of the present invention. As shown in FIG. 1, this hybrid vehicle 1 uses an engine 2 and a motor 3 as drive sources, and can transmit power from the drive sources to wheels 5 via an automatic transmission 4. In the present embodiment, the engine 2 and the motor 3 are directly connected, and are configured to rotate at the same rotational speed Ne. The automatic transmission 4 in the present embodiment uses a stepped automatic transmission (AT).
[0016]
Further, the hybrid vehicle 1 includes a control device (ECU) 6. The control device 6 is connected to various sensors 7 to 10 to be described later, selects an appropriate driving mode from a plurality of driving modes provided in advance based on input values from the sensors 7 to 10, and controls the selected driving mode. Control commands are issued to the engine 2, the motor 3, and the automatic transmission 4 according to the mode as shown by arrows A to C. The various sensors 7 to 10 include an engine speed detection sensor 7 connected to the engine 2 and detecting the speed Ne of the engine 2, a gear position detection sensor 8 for detecting a gear position (GP) in the automatic transmission 4, There are a vehicle speed detection sensor 9 connected to the output shaft of the tire 5 for detecting a vehicle speed, an accelerator opening sensor 10 for detecting an amount of depression of an accelerator pedal (not shown), and the like.
[0017]
The hybrid vehicle 1 according to the present embodiment has an EV traveling mode in which the vehicle can travel only with the motor 3, and an engine traveling mode in which the vehicle travels by driving at least the engine. Here, the engine traveling mode includes a mode in which the vehicle travels with the engine alone and a mode in which the vehicle travels with both the engine and the motor. These are collectively referred to as an engine traveling mode.
[0018]
In the hybrid vehicle 1 described above, the transition of the driving mode is performed as follows. FIG. 2 is a time chart showing a transition process from the EV traveling mode to the engine traveling mode (ENG traveling mode). In the figure, GP indicates the gear position of the automatic transmission 4 and Ne indicates the rotation speed of the engine 2.
[0019]
FIG. 3 is a process chart showing the control performed according to the time chart shown in FIG. As shown in step S10 in the figure, it is determined whether or not the current travel mode is the EV travel mode. If the determination is "YES", the flow proceeds to step S12, and the determination is "NO". In this case, the process proceeds to step S14. If the process has proceeded to step S14, the current traveling mode (EV traveling mode) is continued, and the processing of this step is terminated. In step S12, it is determined whether there is a request to shift to the ENG traveling mode. This determination is made by the ECU 6 based on the depression amount of the accelerator pedal, the vehicle speed, and the like. If the determination is "YES", the flow proceeds to step S16. If the result of the determination is "NO", the operation proceeds to step S14 described above, where the current traveling mode is continued, and the processing of this step ends.
[0020]
In step S14, by checking the rotation speed Ne of the engine 2, it is determined whether or not this rotation speed is equal to or lower than the target restart rotation speed (see the dashed line in FIG. 2). If the determination is "YES", the flow proceeds to step S18; if the determination is "NO", the flow proceeds to step S20. In step S18, the gear position (GP) is shifted to the lower gear (shift from 4th to 3rd), thereby increasing the rotation speed of the engine 4. Then, after a lapse of a predetermined time, the determination in step S16 is performed again.
[0021]
In the present embodiment, when the determination result is "NO" again in step S16, the gear position is further shifted to the lower gear. As a result, the number of revolutions can be reliably set to be higher than the target rotation speed, and the mode can be shifted in a shorter time.
[0022]
In step S20, fuel injection to engine 2 is started (FI return). Then, as shown in step S22, the rotation speed of the motor 3 is synchronized with the rotation speed Ne of the driven engine 2 to reduce the torque fluctuation at the tire end and suppress the shock, thereby improving the fuel efficiency of the engine 2. I am planning. Then, as shown in step S24, the motor 3 and the engine 2 are controlled such that the driving force (tire end driving force) to the wheels 3 becomes the required driving force, and the engine running mode target rotation speed (see FIG. After the rotational speed is higher than (see the broken line), as shown in step S26, the operation shifts to ENG traveling. Thus, a series of processing ends.
[0023]
FIG. 4 is a time chart showing a transition process from the engine traveling mode (ENG traveling mode) to the EV traveling mode. In the figure, GP indicates the gear position of the automatic transmission 4 and Ne indicates the rotation speed of the engine 2.
[0024]
FIG. 5 is a process chart showing the time chart control shown in FIG. As shown in step S30 in the figure, it is determined whether or not the current travel mode is the ENG travel mode. If the determination is "YES", the flow proceeds to step S32, and the determination is "NO". In this case, the process proceeds to step S34. If the process has proceeded to step S34, the current traveling mode (ENG traveling mode) is continued, and the processing of this step is ended. In step S32, it is determined whether or not there is a request to shift to the EV running mode in the same manner as in step S12 described above. If the result of the determination is "YES", the flow proceeds to step S36. If the result of the determination is "NO", the flow proceeds to step S34 to continue the current traveling mode and terminate the processing of this step.
[0025]
In step S36, by checking the engine speed Ne, it is determined whether or not this engine speed is equal to or less than the target restart engine speed (see the dashed line in FIG. 2). When the determination is "YES", the flow proceeds to step S40, and when the determination is "NO", the flow proceeds to step S38. In step S38, the gear position (GP) of the automatic transmission 4 is shifted to a higher gear (shift from 3rd to 4th), and the rotation speed of the engine 4 is reduced. Then, after the elapse of a predetermined time, the determination in step S36 is performed again.
[0026]
In the present embodiment, if the determination result is "NO" again in step S36, the gear position is further shifted to the higher gear. As a result, the number of revolutions can be reliably reduced to the target rotation speed or less, and the mode can be shifted in a shorter time.
[0027]
In step S40, fuel injection to engine 2 is stopped (FI stop). Then, since the engine 2 does not exhibit the driving force, it is possible to shift to the EV independent traveling as shown in step S42. Thus, the above-described series of processing ends. As described above, at the time of the transition to the EV running, the engine 2 is prevented from having an unnecessarily high rotation speed, so that the load on the motor 3 is reduced and the fuel efficiency can be greatly improved.
[0028]
In the above-described embodiment, the case where the automatic transmission is a stepped type (AT) has been described. However, the present invention is not limited to this, and is also applicable to a case of a stepless type automatic transmission (CVT). can do. In this case, when shifting from the EV running mode to the engine running mode, the automatic transmission is controlled to set the engine speed to a speed higher than the restart target speed and to start fuel injection. The engine speed may be controlled by the motor to a speed higher than an engine running mode target speed for shifting to the engine running mode. Further, when the engine speed is higher than the target restart speed when shifting from the engine drive mode to the EV drive mode, the engine is set to a speed lower than the target restart speed by the automatic transmission. In this case, the fuel injection to the engine may be stopped to shift to the EV running mode at or below the above-mentioned target restart speed.
[0029]
【The invention's effect】
As described above, according to the invention described in claim 1, when the engine speed is lower than the target restart speed when the engine speed is shifted from the EV running mode to the engine running mode, the engine speed is reduced. The automatic transmission is controlled so that the engine speed is higher than the restart target engine speed, so that the engine speed can be surely higher than the restart target engine speed. Even when driving by injection, torque fluctuation can be suppressed within a certain range. Thus, noise generated due to torque fluctuation when shifting from the EV running mode to the engine running mode can be suppressed, and drivability is improved. Further, in the EV running mode, the engine is controlled at a rotation speed equal to or lower than the target restart rotation speed, thereby improving fuel efficiency.
[0030]
According to the second aspect of the present invention, the rotation speed of the engine can be set higher than the target restart rotation speed in a shorter time, and the transition of the driving mode can be performed more smoothly.
[0031]
According to the third aspect of the present invention, when shifting from the engine running mode to the EV running mode, the automatic transmission is controlled so that the engine speed is equal to or lower than the target restart speed. Thus, the engine speed can be reliably reduced to the restart target speed or less. For this reason, at the time of the transition to the EV running, the rotation speed of the engine can be sufficiently suppressed, and the driving force required for the motor can be reduced accordingly, and the fuel efficiency can be improved.
[0032]
According to the invention described in claim 4, the engine speed can reach the restart target speed in a shorter time, and the transition of the running mode can be performed more smoothly.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a main configuration of a hybrid vehicle according to an embodiment of the present invention.
FIG. 2 is a time chart showing a transition process of a traveling mode by the hybrid vehicle shown in FIG.
FIG. 3 is a process chart showing control performed according to the time chart shown in FIG. 2;
FIG. 4 is a time chart showing a transition process of a traveling mode by the hybrid vehicle shown in FIG. 1;
FIG. 5 is a process chart showing control performed according to the time chart shown in FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Engine 3 Motor 4 Transmission 5 Vehicle 6 Control device (ECU)
7 Sensor

Claims (4)

An EV traveling mode in which an engine and a motor are used as driving sources and an automatic transmission for transmitting power from the driving source to wheels, and an EV traveling mode in which the vehicle travels using only the power of the motor; A hybrid vehicle comprising:
In the case of the EV running mode, the engine is controlled at a rotation speed equal to or lower than the restart target rotation speed, and
If the engine speed is equal to or less than the restart target speed when the vehicle shifts from the EV drive mode to the engine drive mode, the automatic transmission is controlled to increase the engine speed above the restart target speed. Control means for starting fuel injection at a rotation speed of, and controlling the rotation speed of the engine to a rotation speed higher than a target rotation speed of an engine drive mode in which the motor is shifted to the engine drive mode. A hybrid vehicle characterized by the following. 2. The automatic transmission according to claim 1, wherein when the rotation speed of the engine is equal to or lower than the target restart rotation speed, the automatic transmission continuously controls the rotation speed to be equal to or higher than the target restart rotation speed. 3. The hybrid vehicle as described. An EV traveling mode in which an engine and a motor are used as driving sources and an automatic transmission for transmitting power from the driving source to wheels, and an EV traveling mode in which the vehicle travels using only the power of the motor; A hybrid vehicle comprising:
When the engine speed is higher than the target restart speed when the engine shifts from the engine drive mode to the EV drive mode, the engine is set to a speed lower than the target restart speed by the automatic transmission. A hybrid vehicle comprising control means for stopping fuel injection into the vehicle and controlling to shift to an EV running mode at or below the restart target rotation speed. 4. The automatic transmission according to claim 3, wherein when the rotation speed of the engine is higher than the target rotation speed, the automatic transmission continuously controls the rotation speed to be equal to or lower than the target rotation speed. A hybrid vehicle according to claim 1.

Images