JP2797863B2 - Hybrid electric vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hybrid electric vehicle equipped with an auxiliary engine for driving a generator when battery power is insufficient.

[0002]

2. Description of the Related Art There has been known a so-called series hybrid electric vehicle in which a generator and an engine are mounted together with a driving motor, and when the power of a battery is insufficient, the generator is driven by the engine to supplement the power. Have been.

In this type of hybrid electric vehicle, start and stop of an engine are controlled based on a charge / discharge state of a battery, for example, a battery terminal voltage, as disclosed in Japanese Patent Application Laid-Open No. 3-143201. It has become. In other words, the engine is stopped when the battery is sufficiently charged, the driving motor is driven by the battery power, and the vehicle travels. However, when the terminal voltage falls below a predetermined value, the engine starts, and the power is generated. Drive the machine. The power of the generator is supplied to the drive motor and used for charging the battery, so that the battery terminal voltage is recovered. At this point, the engine stops.
The output of the engine is automatically controlled by an actuator or the like linked to the throttle valve so that the rated speed of the generator is attained.

[0004]

In the conventional configuration in which the start and stop of the engine are simply controlled based on the state of charge / discharge of the battery, for example, a pattern in which the vehicle travels toward a city after traveling in a suburb is considered. Occasionally, suburban driving is performed with battery power, and then the engine is frequently started during traffic congestion in the city area, which tends to cause a large amount of exhaust emissions in urban areas where vehicles are densely packed. There is a defect. In other words, it is preferable that the vehicle runs with only the battery power as much as possible during traffic jams. However, the above-mentioned conventional vehicle does not consider this point at all.

[0005]

Therefore, in the present invention, the start and stop of the engine are controlled in consideration of the vehicle speed. That is, the hybrid electric vehicle according to the present invention includes a driving motor for driving the vehicle, a chargeable / dischargeable battery serving as a power supply for the driving motor, a generator for charging the battery, and a drive for driving the generator. Charging / discharging state detecting means for detecting a charging / discharging state of the battery, average vehicle speed detecting means for detecting an average vehicle speed of the vehicle, starting the engine based on the charging / discharging state and the average vehicle speed, Engine start / stop control means for controlling stop.

The engine start / stop control means has, for example, a control characteristic of starting the engine at a stage where the battery discharge amount is small when the average vehicle speed is high. Alternatively, the engine is always operated when the average vehicle speed is equal to or higher than a predetermined value. Alternatively, the engine is not stopped when the average vehicle speed is equal to or higher than a predetermined value.

[0007]

When the battery power becomes insufficient, the engine is started by the engine start / stop control means, and when the battery is recovered by charging, the engine is stopped.
Here, in the above configuration, the start and stop of the engine are controlled not only in the battery charge / discharge state but also in consideration of the average vehicle speed, and the engine is not operated as much as possible at a low vehicle speed. Charging is performed with emphasis.

In general, the average vehicle speed is high in suburban driving,
The engine is started or continuously operated at a stage where the battery discharge amount is small. Thus, during suburban travel, the battery is maintained at or near full charge. For this reason, the frequency of engine operation after the shift to the city area traveling is reduced, and the emission of emissions is suppressed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the structure of a hybrid electric vehicle according to the present invention. The drive motor 1 is composed of, for example, a three-phase induction motor,
Is driving. The drive motor 1 is basically driven by the power of a battery 3 and includes a motor drive control device 4 that converts a DC voltage of the battery 3 into a three-phase AC voltage and controls the speed thereof. ing.

The battery 3 is provided with a charge / discharge state detecting device 5 for detecting the charge / discharge state.

The engine 6 is composed of, for example, a gasoline engine and drives a generator 7. A catalyst device 8 is interposed in the exhaust system of the engine 6.
Also, in order to variably control the amount of intake air in the intake passage,
A solenoid type air control valve 9 is interposed. The air control valve 9 is controlled by an air control valve control device 10 using, for example, a microcomputer system. FIG. 3 shows an example of the air control valve 9, and a housing 31.
A spool 34 is provided to open and close the inlet port 32 and the outlet port 33 of the spool 3.
4 is provided at one end.
The solenoid 35 is turned on and off by a pulse signal of a predetermined cycle, and the intake air amount of the engine 6 can be continuously controlled by variably controlling the ON duty ratio.

The engine 6 includes a starter motor (not shown),
It has an ignition device and a fuel supply device, and these are controlled by the engine start / stop control device 11. The engine start / stop control device 11 operates based on a signal from the charge / discharge state detection device 5 described above.

Reference numeral 12 denotes an average vehicle speed detecting device for detecting an average vehicle speed of the vehicle. The average vehicle speed detection device 12 counts the number of revolutions of the drive shaft per unit time to determine the vehicle speed, for example, and averages the vehicle speed detected by the pulse counter over a relatively long time (for example, three minutes). And a switching circuit.

As shown in FIG. 2, the generator 7 uses a three-phase AC generator having an armature coil 21 and a field coil 22. The three-phase full-wave generator converts an AC voltage into a DC voltage. A rectifier circuit 23 and an automatic voltage regulator (AVR) 24 for controlling the current of the field coil 22 so as to keep the voltage constant are provided. The electric power generated by the generator 7 is supplied to the drive motor 1, and the surplus is used for charging the battery 3.

As shown in FIG. 2, the charging / discharging state detecting device 5 for the battery 3 includes a Hall element 25 for detecting a magnetic field due to the charging / discharging current of the battery 3, DOD for calculating DOD (battery discharge depth) (%) by referring to a detection circuit 26 and a map stored in a memory based on the current value and the battery voltage
The calculation circuit 27 and the DOD value are stored in an appropriate time (for example, 5
And an averaging circuit 28 for averaging in minutes. FIG. 4 shows an example of a map in the DOD calculation circuit 27. In the DOD, 0% indicates a fully charged state and 100% indicates a completely discharged state.

The engine start / stop control device 11 includes the D
Starting the engine 6 based on the OD value and the average vehicle speed,
Stop control is being performed. The engine start / stop control device 11 is actually configured by a microcomputer system together with the air control valve control device 10. FIG. 5 shows the engine start / stop control device 11.
Shows the control characteristics at OFF → ON in FIG.
The start of the engine 6 is performed along the line S1 and ON →
The engine 6 is stopped along the OFF line S2. For example, in a low vehicle speed region where the average vehicle speed is 30 km / h or less, the OFF → ON line S1 is at the position of DOD = 60%, and the ON → OFF line S2 is at the position of DOD = 20%. Therefore, when the DOD value becomes 60% or more during traveling by the battery 3, the engine 6 is started, and the power generation by the generator 7 is started. Then, when the DOD value recovers to 20% or less as a result of charging by the generator 7, the engine 6 stops. When the engine 6 is started, a starter motor (not shown) operates, but the energization of the starter motor is stopped when the rotation speed of the engine 6 is detected to be equal to or higher than a predetermined rotation speed.

The above OFF which defines the start of the engine 6 →
In the region where the average vehicle speed is 30 km / h or more, the ON line S1 has such a characteristic that the DOD gradually decreases toward the smaller DOD as the vehicle speed increases. That is, as the average vehicle speed increases, the engine 6 is started at a stage where the amount of discharge is small, and the battery 3
Is started. At the point where the average vehicle speed is 90 km / h, the OFF → ON line S1 has DOD = 0%. Therefore,
In a high vehicle speed region of 90 km / h or more, the engine 6
It is always operated regardless of the size of D.

Note that the vehicle speed (90 km / h in the example of FIG. 5) at the point where the OFF → ON line S1 is at DOD = 0%, that is, at the point where the engine 6 is always in the operating state is set near the balance vehicle speed. This balanced vehicle speed is a vehicle speed at which the output of the generator 7 and the input of the drive motor 3 that are rated are balanced assuming that the vehicle is running at a constant vehicle speed, that is, the battery 3 is neither charged nor discharged. No vehicle speed.

On the other hand, ON which defines the stop of the engine 6 →
The OFF line S2 has a characteristic in which the average vehicle speed is equal to or higher than 30 km / h and also gradually decreases toward the smaller DOD as the vehicle speed increases, and DOD = 0 at the point of 60 km / h.
%. In other words, the higher the average vehicle speed, the more the charging is performed to a state closer to full charge, and in the high speed region of 60 km / h or more, the engine 6 once started does not stop.

As described above, in the above configuration, the battery 3 is positively charged using the engine 6 during suburban driving when the average vehicle speed is generally high. Further, in a relatively low vehicle speed region, the engine 6 is not started until the battery 3 discharges considerably, and the engine 6 is stopped earlier. Therefore, when driving in urban areas, especially in situations where vehicles are densely packed and congested,
The vehicle runs using the battery 3 and the frequency of operation of the engine 6 is greatly reduced.

In a region where the vehicle speed is 60 km / h or more,
Once started, the engine 6 does not stop regardless of the state of charge. This is because the start of the engine 6 is performed in an area where the DOD is small (for example, 30% or less). For example, if the DOD is stopped at about 10 to 20%, the start and stop of the engine 6 frequently occur. This avoids the problem of being repeated. Since most of the problematic exhaust emissions are emitted at the time of starting, even if the operation time of the engine 6 is shortened, the total emission of the emission increases when the number of starts and stops increases.
Therefore, the stop of the engine 6 is prohibited in the area of 60 km / h or more as described above.

The engine 6 does not stop as described above.
In the range of 0 km / h or more, the automatic voltage regulator 24 controls the field current so that the battery 3 is not overcharged, and the output itself of the engine 6 is controlled by the air control valve 9.
Is controlled so as to follow the load fluctuation of the generator 7 via the. The point of 60 km / h is a vehicle speed balanced at, for example, approximately 50% of the maximum output of the generator 7.
In the range of 0 km / h or more, by performing the output adjustment of 50 to 100%, it is possible to prevent the overcharge of the battery 3 and to always keep the battery 3 in a fully charged state.

[0024]

As is apparent from the above description, in the hybrid electric vehicle according to the present invention, the operation of the engine for charging the battery is mainly performed when the vehicle is running at high speed, that is, when traveling in a suburb, and a full charge is performed. Alternatively, the battery is kept in a state close to this. For this reason, after shifting to urban driving, operation mainly by the battery is performed, and operation of the engine is suppressed. Therefore, emission emissions in a city area where vehicles are densely packed are greatly suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing one embodiment of a hybrid electric vehicle according to the present invention.

FIG. 2 is a circuit diagram showing a configuration of a charge / discharge state detection device.

FIG. 3 is a sectional view showing an example of an air control valve.

FIG. 4 is an explanatory diagram showing an example of a DOD value map.

FIG. 5 is a characteristic diagram showing control characteristics of starting and stopping the engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drive motor 3 ... Battery 5 ... Charge / discharge state detection device 6 ... Engine 7 ... Generator 8 ... Catalyst device 9 ... Air control valve 10 ... Air control valve control device 11 ... Engine start / stop control device 12 ... Average vehicle speed detection apparatus

Claims (4)

(57) [Claims] 1. A driving motor for driving a vehicle, a chargeable / dischargeable battery serving as a power source for the driving motor, a generator for charging the battery, an engine for driving the generator, Charge / discharge state detecting means for detecting a charge / discharge state, average vehicle speed detecting means for detecting an average vehicle speed of the vehicle, and engine start / stop for controlling start / stop of the engine based on the charge / discharge state and the average vehicle speed. A hybrid electric vehicle comprising control means. 2. The hybrid electric system according to claim 1, wherein said engine start / stop control means has a control characteristic of starting the engine at a stage where the battery discharge amount is small when the average vehicle speed is high. Car. 3. The hybrid electric vehicle according to claim 1, wherein the engine start / stop control means operates the engine constantly when the average vehicle speed is equal to or higher than a predetermined value. 4. The hybrid electric vehicle according to claim 1, wherein said engine start / stop control means does not stop the engine when the average vehicle speed is equal to or higher than a predetermined value.