JP2008074252A - Controller for hybrid electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a hybrid electric vehicle by which an exhaust gas performance is kept almost constant over the use period of the vehicle. <P>SOLUTION: The controller for the hybrid electric vehicle is provided with: a power generator 4 to be driven by an engine 2 for charging a battery 8; and a motor 10 for receiving a power to be supplied from the battery 8, and for driving a driving wheel 18. A basic power generation point is set at a more deteriorating side than the operating point where the predetermined emission gas characteristics of the engine 2 become the most satisfactory as a power generation point as the operating point of the engine 2 in the case of charging the battery 8, and when charging the battery 8 based on the output of the power generator 4, the engine 2 is operated at a power generation point shifted from the basic power generation point to the direction where the emission gas characteristics are improved according to the level of deterioration of the battery 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control apparatus for a hybrid electric vehicle, and more particularly, a series in which an engine is dedicated to power generation, power generated by a generator is stored in a battery, and driving wheels are driven by a motor that operates with power supplied from the battery. The present invention relates to a control device for a hybrid electric vehicle.

Conventionally, the engine is used exclusively for driving the generator, the generated power of the generator is stored in the battery, the battery power is supplied to the motor, and the driving wheels of the motor are used to drive the drive wheels of the vehicle. Type hybrid electric vehicles have been developed and put into practical use.
In such a series hybrid electric vehicle, when the charging rate of the battery decreases, the engine is operated to drive the generator, and the generated power of the generator is charged to the battery so that the charging rate does not decrease excessively. ing.

The power generation point that is the operating point of the engine at this time is defined by, for example, the engine speed and output torque, and various combinations of engine speed and output torque can be considered even with the same generated power. It is conceivable to perform engine operation control at a power generation point that prioritizes any one of the various characteristics of the.
In Patent Document 1, a basic power generation point that optimizes the fuel efficiency of the engine is determined as such a power generation point, and the power generation point is shifted from the basic power generation point in accordance with the temperature of the catalyst for purifying the exhaust of the engine. Series hybrid electric vehicles have been proposed.

Further, instead of giving priority to the fuel consumption of the engine, it is conceivable to prioritize the engine exhaust gas characteristics and set the power generation point so that the engine exhaust gas characteristics are the best.
JP 11-82093 A

  However, the battery generally deteriorates over time, and the internal resistance tends to increase with the progress of deterioration. As the internal resistance of the battery increases, energy loss inside the battery increases, and the time required for charging the battery is extended. Therefore, the operation time of the engine for charging the battery is extended, and the amount of engine exhaust gas increases accordingly.

Vehicle exhaust gas performance is evaluated by the amount of air pollutants contained in the exhaust gas, but the initial exhaust gas performance of the vehicle cannot be maintained due to the increase in the amount of engine exhaust gas. There arises a problem that the exhaust gas performance at the time and the exhaust gas performance after aging are different.
Normally, a vehicle is evaluated for various performances in the state of a new vehicle, but if the exhaust gas performance of the vehicle differs between the new vehicle and after the lapse of time, the vehicle cannot be evaluated properly. There is.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a control apparatus for a hybrid electric vehicle capable of maintaining the exhaust gas performance substantially constant over the period of use of the vehicle. There is.

  In order to achieve the above object, a control device for a hybrid electric vehicle of the present invention is supplied from an engine, a generator driven by the engine, a battery charged by the output of the generator, and the battery. A motor that operates by receiving electric power and drives a driving wheel of a vehicle, a deterioration degree detecting means that detects a degree of deterioration of the battery, and a power generation point that is an operating point of the engine when the battery is charged. When the basic power generation point is set on the side where the predetermined exhaust gas characteristics are worse than the best operating point, and the battery is charged by the output of the generator, the battery detected by the deterioration degree detecting means is detected. Depending on the degree of deterioration, the power generation point shifted from the basic power generation point to the direction in which the exhaust gas characteristics improve. Characterized in that a control means for operating the engine (claim 1).

According to the control apparatus for a hybrid electric vehicle configured as described above, when electric power is supplied from the battery to the motor, the motor drives the driving wheels so that the vehicle travels and the generator driven by the engine The generated power is charged to the battery.
The power generation point, which is the engine operating point when the battery is charged by the generator, is a predetermined discharge of the engine because the battery has not deteriorated shortly after the new battery is mounted on the vehicle. This is the basic power generation point set on the worse side of the operating point where the gas characteristics are best. Further, when the battery deteriorates as the battery usage period elapses, the power generation point shifts from the basic power generation point to the direction of improving the exhaust gas characteristics in accordance with the degree of battery deterioration.

In the hybrid electric vehicle control device, the control means shifts the power generation point while maintaining the output of the engine substantially constant (claim 2).
According to the hybrid electric vehicle control apparatus configured as described above, when the power generation point is shifted from the basic power generation point according to the degree of deterioration of the battery, the output of the engine is maintained substantially constant.

Furthermore, in the control apparatus for the hybrid electric vehicle, the deterioration degree detecting means detects an internal resistance of the battery as the deterioration degree (Claim 3).
According to the hybrid electric vehicle control apparatus configured as described above, the internal resistance of the battery is detected as the degree of deterioration, and the power generation point is improved from the basic power generation point to the improvement of the exhaust gas characteristics in accordance with the increase in the internal resistance of the battery. Will move.

Further, in the control device for the hybrid electric vehicle, the control means is worse than a point where the exhaust gas characteristic of the engine is best based on an increase in the internal resistance of the battery during a predetermined period of use of the battery. The basic power generation point is set on the side to be operated (claim 4).
According to the hybrid electric vehicle control apparatus configured as described above, the exhaust gas characteristics of the engine are worse than the best point based on the increase in the internal resistance of the battery during a predetermined battery use period. Basic power generation points are set in

Furthermore, in the control device for the hybrid electric vehicle, the power generation point is defined by the engine speed and the output torque, and the control means is more than the point where the exhaust gas characteristic of the engine is the best. The basic power generation point is set on the side having high output torque and low engine speed (Claim 5).
According to the control apparatus for a hybrid electric vehicle configured as described above, the basic power generation point is set on the side where the output torque is higher and the engine speed is lower than the point where the exhaust gas characteristic of the engine is the best.

  According to the control apparatus for a hybrid electric vehicle of the present invention, when a new battery is installed in the vehicle, it is sooner than the operating point where the exhaust gas characteristics are best when the battery is charged by the generator. The engine is operated at the basic power generation point set on the worse side. And as the battery deteriorates, the power generation point shifts from the basic power generation point in the direction of improving the exhaust gas characteristics according to the degree of battery deterioration, so even if the time required for charging is extended due to battery deterioration, the engine By improving the exhaust gas characteristics of the vehicle, the exhaust gas performance of the vehicle can be maintained almost constant over the period of use from the time of a new vehicle. Therefore, even when the vehicle is a new vehicle, it is possible to appropriately evaluate the exhaust gas performance of the vehicle.

  According to the control device for a hybrid electric vehicle of claim 2, when the power generation point is shifted from the basic power generation point according to the degree of deterioration of the battery, the engine output is maintained substantially constant. The time required for charging the battery does not fluctuate due to a change in engine output. As a result, it becomes possible to maintain the exhaust gas performance of the vehicle substantially constant with higher accuracy by shifting the power generation point according to the degree of deterioration of the battery.

  Furthermore, according to the control device for a hybrid electric vehicle of claim 3, the internal resistance of the battery directly related to the charging time of the battery is detected as the degree of deterioration, and from the basic power generation point according to the increase in the internal resistance of the battery. Since the power generation point is shifted in the direction of improving the exhaust gas characteristics, the exhaust gas performance of the vehicle can be maintained almost constant with higher accuracy.

  According to the control apparatus for a hybrid electric vehicle of claim 4, the engine exhaust gas characteristics are deteriorated from the best point based on the increase in the internal resistance of the battery during a predetermined battery use period. Since the basic power generation point is set to the power generation point, it is possible to appropriately shift the power generation point over the period of use of the battery and maintain the exhaust gas performance of the vehicle substantially constant.

  Furthermore, according to the control device for a hybrid electric vehicle of claim 5, the basic power generation point is set on the side where the output torque is higher and the engine speed is lower than the point where the exhaust gas characteristic of the engine is the best. In general, at the same engine output, the higher the output torque and the lower the engine speed, the better the fuel economy of the engine. Therefore, it is possible to improve the fuel efficiency of the engine while maintaining the vehicle's exhaust gas performance almost constant. It becomes.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a main part configuration diagram of a series hybrid electric vehicle 1 equipped with a control device according to an embodiment of the present invention.
The output shaft of the engine 2 which is a diesel engine is connected to the rotating shaft of the generator 4, and the generated power of the generator 4 driven by the engine 2 is stored in the battery 8 via the inverter 6.

The inverter 6 adjusts the current flowing between the generator 4 and the battery 8 so that the battery 8 is appropriately charged by the electric power supplied from the generator 4.
Further, the generator 4 operates as a motor when electric power is supplied from the battery 8 via the inverter 6 when the engine 2 is stopped, and also has a function of cranking the engine 2.

On the other hand, the hybrid electric vehicle 1 is equipped with a motor 10 for traveling, and the output shaft of the motor 10 has left and right drive wheels 18 via a speed reducer 12, a differential device 14 and a pair of drive shafts 16. It is connected to.
The electric power of the battery 8 is supplied to the motor 10 via the inverter 6, and the driving force transmitted from the motor 10 to the driving wheel 18 can be adjusted by adjusting the electric power supplied to the motor 10 by the inverter 6. It can be done.

  Further, at the time of vehicle braking, the motor 10 operates as a generator, and kinetic energy generated by the rotation of the drive wheels 18 is transmitted to the motor 10 and converted into AC power, thereby generating regenerative braking torque. Then, this AC power is converted into DC power by the inverter 6 and then charged to the battery 8, and the kinetic energy due to the rotation of the drive wheels 18 is recovered as electric energy.

The HEV-ECU (control means) 20 includes the engine 2, the generator 4, the inverter 6, the motor 10, the driving state of the motor 10 and the vehicle, and information from the engine ECU 22 and the battery ECU 24. And integrated control is performed so that the motor 10 operates properly.
That is, the HEV-ECU 20 is connected to an accelerator opening sensor 28 that detects an operation amount of the accelerator pedal 26, and controls the inverter 6 according to the operation amount of the accelerator pedal 26 detected by the accelerator opening sensor 28. Thus, the driving force transmitted from the motor 10 to the driving wheels 18 is adjusted according to the driver's request.

Further, at the time of vehicle braking, the HEV-ECU 20 controls the regenerative braking force generated by the motor 10 by controlling the inverter 6 to adjust the power supplied from the motor 10 operating as a generator to the battery 8.
Further, the HEV-ECU 20 sends a command to the engine ECU 22 to drive the generator 4 by the engine 2 so that the engine 2 operates at a predetermined operating point when the battery 8 needs to be charged. The inverter 6 is controlled so that the battery 8 is properly charged by generating predetermined generated power from the battery.

  The engine ECU 22 is provided to perform overall operation control of the engine 2, and based on a command from the HEV-ECU 20, start / stop control of the engine 2 for driving the generator 4, and from the generator 4 to the battery 8 controls the operation of the engine 2 to obtain the generated electric power necessary for charging 8 and adjusts the fuel injection amount and the injection timing of the engine 2 and sends various information obtained from the engine 2 to the HEV-ECU 20. sending.

  The battery ECU (degradation degree detection means) 24 detects the temperature of the battery 8, the voltage of the battery 8, the current flowing between the inverter 6 and the battery 8, and the charge of the battery 18 from these detection results. While calculating | requiring a rate, the internal resistance of the battery 8 is calculated | required as what shows the deterioration degree of the battery 8. FIG. And the calculated | required charging rate and internal resistance are sent to HEV-ECU20 with the said detection result.

The internal resistance of the battery 8 is calculated from the voltage of the battery 8 and the history of the current flowing between the inverter 6 and the battery 8, and the calculation method itself is known.
When the driver depresses the accelerator pedal in the series hybrid electric vehicle 1 configured as described above, the HEV-ECU 20 detects the operation amount of the accelerator pedal 26 detected by the accelerator opening sensor 28 and a travel speed sensor (not shown). Based on the vehicle traveling speed, a drive torque to be transmitted to the drive wheels 18 is obtained, and the inverter 6 is controlled so that the motor 10 generates this drive torque.

As a result, the electric power of the battery 24 is supplied to the motor 10 via the inverter 6, and the drive torque generated by the motor 10 is transmitted to the left and right drive wheels 18 via the speed reducer 12, the differential device 14 and the drive shaft 16. The vehicle runs.
When the battery ECU 24 detects that the charging rate of the battery 8 has decreased to the predetermined lower limit charging rate due to the power supply to the motor 10, the HEV-ECU 20 receives information from the battery ECU 24 and determines that the battery 8 needs to be charged. Then, the inverter 6 is controlled so as to operate the generator 4 as a motor, and a command is sent to the engine ECU 22 to start supplying fuel to start the engine 2.

In this way, the generator 4 operates as a motor to crank the engine 2, and the engine ECU 22 receives a command from the HEV-ECU 20 and starts supplying fuel to the engine 2, thereby starting the engine 2.
When the start of the engine 2 is completed, the engine ECU 22 sends information indicating that the start of the engine 2 is completed to the HEV-ECU 20, and the HEV-ECU 20 receives this information and sends the information to the inverter 6 so that the generator 4 operates as a generator. Send control signal. Further, the HEV-ECU 20 controls the inverter 6 so that the generated power of the generator 4 becomes a predetermined power, and is an operating point of the engine 2 when driving the generator 4 that generates power with the predetermined power to the engine ECU 22. Specify the power generation point.

The engine ECU 22 receives an instruction from the HEV-ECU 20 and controls the engine 2 so that the engine 2 operates at a power generation point instructed from the HEV-ECU 20.
Here, the power generation point is determined by the rotation speed and output torque of the engine 2 corresponding to the predetermined power, and when the vehicle is a new vehicle and the battery 8 is not deteriorated, the basic power generation point is used for the engine 2. Driving is performed.

In this embodiment, the NOx emission amount of the engine 2 is defined as the exhaust gas characteristic of the engine 2, and this basic power generation point has the smallest NOx emission amount in the relationship between the engine speed and the output torque at which a predetermined power can be obtained. The operating point increases from the operating point where the exhaust gas characteristics become the best, that is, the operating point becomes worse than the operating point where the exhaust gas characteristics become the best.
FIG. 2 shows an equal NOx emission amount line per unit time when the engine speed and the output torque of the engine 2 are parameters, as a solid curve, and the more it moves in the direction indicated by the arrow D1 in the figure. That is, the NOx emission amount decreases as it moves inward.

In FIG. 2, the curve indicated by the alternate long and short dash line is an equal output line L from which a predetermined generated power can be obtained. In this embodiment, the basic power generation point is set to the operating point a on the equal output line L. As shown in FIG. 2, the operating point a is on the side where the NOx emission amount increases on the iso-output line L than the operating point b where the NOx emission amount is minimum, that is, the exhaust gas characteristics deteriorate. .
When the vehicle is a new vehicle and the battery 8 is new, the engine ECU 22 controls the engine 2 so that the engine speed and output torque correspond to the operating point a that is the basic power generation point instructed by the HEV-ECU 20. To do.

On the other hand, when charging / discharging is repeated and the battery 8 is deteriorated due to aging, and the degree of deterioration gradually increases, the internal resistance of the battery 8 required by the battery ECU 24 also gradually increases accordingly.
When the HEV-ECU 20 receives the information on the internal resistance of the battery 8 obtained by the battery ECU 24, the HEV-ECU 20 performs power generation by the generator 4 according to the increase from the internal resistance of the battery 8 when the battery 8 is not deteriorated. The power generation point instructed to the engine ECU 22 is shifted from the operating point a, which is a basic power generation point, to the direction in which the exhaust gas characteristics of the engine 2 are improved, that is, the direction of the arrow D2 shown in FIG.

The engine ECU 22 controls the engine 2 so that the engine speed and the output torque correspond to the power generation point instructed by the HEV-ECU 20, and the NOx emission amount per unit time from the engine 2 is operated at the basic power generation point. Compared to
Here, when the power generation point is shifted in accordance with the increase in the internal resistance of the battery 8, the increase in the NOx emission amount caused by the extension of the charging time due to the increase in the internal resistance of the battery 8 is offset per unit time. The power generation point is set by the amount of movement that realizes the reduction of the NOx emission amount.

Therefore, although the time required for charging the battery 8 increases due to the deterioration of the battery 8 and the increase in internal resistance, the amount of NOx discharged per unit time from the engine 2 decreases. The total amount of NOx discharged until completion can be made substantially the same as the amount of NOx discharged when the battery 8 is a new vehicle and is not deteriorated.
In this way, even if the time required for charging is extended due to the deterioration of the battery 8, the exhaust gas performance of the vehicle can be maintained at a substantially constant state from the time of the new vehicle. It becomes possible to appropriately evaluate the exhaust gas performance of the vehicle.

The basic power generation point is preferably set as follows.
That is, the battery 8 is replaced with a new one when it has deteriorated to some extent, but the power generation point when the internal resistance immediately before the replacement becomes the operating point where the NOx emission amount is the smallest on the equal output line L in FIG. Let b.
On the other hand, the period until the replacement is determined by the specifications of the battery 8 and the like, and the increase in the internal resistance of the battery 8 within this period is previously grasped by experiments or the like. If the increase in the internal resistance of the battery 8 is obtained, the time required for charging the battery 8 in the state immediately before the replacement can be obtained, so that the total amount of NOx discharged from the start of charging to completion of the battery 8 is obtained. Can be obtained from the NOx emission amount per unit time at the operating point b in FIG. 2 and the time required to charge the battery 8.

The basic power generation point is that the NOx emission amount per unit time obtained by dividing the total NOx emission amount at the time of charging the battery 8 immediately before the replacement thus obtained by the charging time required for the new battery 8 is realized. .
By setting the basic power generation point in this way, the power generation point is appropriately shifted according to the change in the internal resistance of the battery 8 over the entire use period of the battery 8, and the vehicle exhaust gas performance determined by the NOx emission amount is almost the same. It can be kept constant.

  Further, in this embodiment, when the internal resistance changes due to deterioration of the battery 8, the power generation point is shifted on the equal output line L of the equal output line, and the same generated power, that is, the same engine output is maintained. ing. By doing so, the time required for charging the battery 8 does not fluctuate due to a change in the output of the engine 2. Therefore, by shifting the power generation point in accordance with the increase in the internal resistance of the battery 8, the power generation point is further changed. It becomes possible to maintain the exhaust gas performance of the vehicle almost constant with high accuracy.

When the engine 2 is operated at the power generation point designated by the HEV-ECU 20 and the generator 4 is driven to charge the battery 8 with the generated power, the charging rate of the battery 8 gradually increases. It rises.
When the battery ECU 24 detects that the charging rate of the battery 8 has increased to the predetermined upper limit charging rate, the HEV-ECU 20 determines that the charging of the battery 8 has been completed by receiving information from the battery ECU 24, and the engine 2 A command is sent to the engine ECU 22 to stop the supply of fuel to stop the operation, and the inverter 6 is controlled to stop the power generation by the generator 4.

When the engine ECU 22 receives a command from the HEV-ECU 20 and shuts off the fuel supply to the engine 2, the engine 2 stops.
As described above, when the battery 8 is charged by the generator 4 driven by the engine 2, the power generation point shifts from the basic power generation point to the direction of improving the exhaust gas characteristics as the internal resistance of the battery 8 increases. Therefore, even if the time required for charging is extended due to deterioration of the battery 8, the exhaust gas performance of the engine 2 is improved, so that the exhaust gas performance of the vehicle is maintained at a substantially constant state over the period of use from the time of the new vehicle. It becomes possible. Therefore, even when the vehicle is a new vehicle, it is possible to appropriately evaluate the exhaust gas performance of the vehicle.

  In the present embodiment, the internal resistance of the battery 8 obtained by the battery ECU 24 as described above is used as the degree of deterioration of the battery 8. Since the internal resistance of the battery 8 is directly related to the time required for charging the battery 8, the vehicle exhaust gas performance can be accurately obtained by shifting the power generation point in accordance with the increase in the internal resistance of the battery 8. Can be maintained substantially constant.

In addition, when the battery 8 is replaced with a new one for some reason, the internal resistance of the battery 8 obtained by the battery ECU 24 returns to the value when no deterioration has occurred, so the battery 4 is charged by the generator 4. In this case, the engine 2 is operated again at the basic power generation point.
By operating the engine 2 at the basic power generation point, the amount of NOx emission per unit time increases, but since the battery 8 is new, the charging time is shorter than before the battery 8 is replaced. The performance will be the same as the new car.

Therefore, even if the battery 8 is replaced, the exhaust gas performance of the vehicle can be maintained almost constant from the time of the new vehicle.
Further, in the present embodiment, the operating point a of FIG. 2 is used as the basic power generation point. However, the operating point c on the opposite side to the operating point a on the iso-output line L is also per unit time. The NOx emission amount may be the same, and this operating point c may be the basic power generation point, and the power generation point may be shifted in the direction of the operating point b as the internal resistance of the battery 8 increases.

However, in this case, since the output power torque is lower and the engine speed is higher than when the operating point a is the basic power generation point, the fuel consumption of the engine 2 is higher than when the operating point a is the basic power generation point. Will get worse.
That is, by setting the basic power generation point on the side where the high output torque and the low engine speed are obtained with respect to the operating point b that minimizes the NOx emission amount per unit time on the equal output line L, The fuel consumption can be improved.

  In addition, since the power generation point moves toward the operating point b, the exhaust gas performance of the vehicle that is maintained substantially constant is determined by the NOx emission amount per unit time at the operating point b. become. Therefore, the battery 8 is charged with the generated power corresponding to the iso-output line that passes through the operating point where the NOx emission amount per unit time becomes the smallest in the characteristics of the NOx emission amount in FIG. If the basic power generation point is set on the line, the exhaust gas performance of the vehicle can be kept almost constant in a state as good as possible.

Although the description of the control apparatus for a hybrid electric vehicle according to one embodiment of the present invention is finished above, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the power generation point is shifted while maintaining the same generated power, that is, the same engine output, even if the internal resistance changes due to deterioration of the battery 8. In this case, as described above, the time required for charging the battery 8 does not fluctuate due to the output change of the engine 2, so that the exhaust gas performance of the vehicle can be maintained substantially constant with high accuracy. Although there is an advantage that it becomes possible, the power generation point may be shifted while changing the output of the engine 2 instead.

A modification of the above embodiment will be described with reference to FIG.
FIG. 3 shows an equal NOx emission amount line per unit time as a real curve when the engine speed and the output torque of the engine are used as parameters as in FIG.
In FIG. 3, the basic power generation point is set at the operating point d on the equi-output line L1 indicated by the alternate long and short dash line, the engine speed at the operating point d is N1, and the output torque of the engine 2 is Tq. On the other hand, at the operating point e where the exhaust gas characteristic of the engine 2 is the best at the same output torque Tq as the operating point d, the engine speed is N2, which is on the iso-output line L2, which is higher than the iso-output line L1. Therefore, the basic power generation point is on the side that deteriorates from the operating point e at which the exhaust gas characteristics of the engine 2 are best at the output torque Tq.

  When the vehicle is a new vehicle and the battery 8 is new, when the battery 4 is charged by the generator 4, the HEV-ECU 20 instructs the engine ECU 22 about the basic power generation point, and the engine ECU 22 instructs the HEV-ECU 20 to The engine 2 is controlled so that the engine speed N1 and the output torque Tq correspond to the operating point d, which is the basic power generation point.

  On the other hand, when charging and discharging are repeated and the internal resistance of the battery 8 increases due to secular change, the HEV-ECU 20 rotates the engine according to the increase from the internal resistance of the battery 8 when the battery 8 is not deteriorated. By increasing the number from the engine speed N1 at the operating point d, the power generation point is shifted from the operating point d to the operating point e, that is, in the direction in which the exhaust gas characteristics of the engine 2 are improved, and instructed to the engine ECU 22. Since the power generation point instructed at this time is to maintain the output torque of the engine 2 at Tq and increase the engine speed from N1, the output of the engine 2 is increased as compared with the case of the basic power generation point.

The engine ECU 22 controls the engine 2 so that the engine speed and the output torque correspond to the power generation point instructed by the HEV-ECU 20, and the NOx emission amount per unit time from the engine 2 is operated at the basic power generation point. Compared to
Therefore, even if the internal resistance increases due to the deterioration of the battery 8 and the time required for charging the battery 8 increases, the NOx emission amount per unit time from the engine 2 decreases, and thus the battery 8 is completed from the start of charging. The total NOx emission amount up to can be made substantially the same as the NOx emission amount when the battery 8 is a new vehicle that is new and has not deteriorated.

Here, the amount of movement at the time of shifting the power generation point is set in the same manner as in the above embodiment, but in this modification, the output of the engine 2 increases as described above due to the shift of the power generation point. Since the time required for charging the battery 8 is reduced by that amount, the accuracy in maintaining the exhaust gas characteristics of the vehicle substantially constant as compared with the above embodiment is somewhat lowered.
In order to prevent a decrease in accuracy due to the shortening of the charging time, for example, the movement amount of the power generation point corresponding to the increase in the internal resistance of the battery 8 is corrected in the decreasing direction by the increase in the output of the engine 2. Good.

  In the above modification, the power generation point is shifted by changing the engine speed while maintaining the output torque of the engine 2 constant. However, both the output torque of the engine 2 and the engine speed are changed. Thus, the power generation point may be shifted, or the power generation point may be shifted by changing the output torque of the engine 2 while maintaining the engine speed constant.

In either case, the basic power generation point is set on the side where the exhaust gas characteristics deteriorate from the operating point where the exhaust gas characteristics of the engine 2 are optimal, and the exhaust gas characteristics from the basic power generation point according to the increase in the internal resistance of the battery 8. The power generation points should be shifted in the direction of improvement.
Further, when the power generation point is shifted by changing both the output torque of the engine 2 and the engine speed, the operating point at which the NOx emission amount per unit time becomes the smallest in the characteristics of the NOx emission amount of FIG. Is an operating point e, an operating point other than the operating point e can be selected as appropriate according to the operating conditions of the engine 2 and used as a basic power generation point.

In this case, as the internal resistance of the battery 8 increases, the power generation point is shifted from the basic power generation point toward the operating point e where the amount of NOx emission per unit time is minimized, so that the exhaust gas performance of the vehicle is as good as possible. It is possible to maintain a substantially constant state.
Further, in the above modification, the operating point e is set as the operating point at which the exhaust gas characteristic of the engine 2 is the best at the same output torque Tq as the operating point d that is the basic power generation point. The operating point e where the NOx emission amount per unit time is the smallest in the quantity characteristic may be set as the operating point e, and the operating point d of the basic power generation point may be set at the same output torque as the operating point e.

Also in this case, as the internal resistance of the battery 8 increases, the power generation point shifts from the basic power generation point toward the operating point e where the amount of NOx emission per unit time is the smallest. Can be maintained substantially constant while keeping the state as good as possible.
In the above embodiment and the modification, the internal resistance directly related to the charging time of the battery 8 is used as the deterioration degree of the battery 8, but the deterioration degree is detected by something other than the internal resistance. Also good. That is, since the time required for charging the battery 8 increases as the degree of deterioration of the battery 8 increases, the same effect can be obtained by detecting the degree of deterioration other than the internal resistance of the battery 8.

The degree of deterioration of the battery 8 may be estimated based on, for example, a temperature change of the battery 8 or a voltage fluctuation, or may be estimated in a period that has elapsed since the start of use of the battery 8. May be.
Further, in the above-described embodiment and modification, the NOx emission amount is used as the exhaust gas characteristic of the engine 2, which is particularly effective when the engine 2 is a diesel engine. Emissions of components other than NOx such as carbon) and HC (hydrocarbon) may be used, and target exhaust gas characteristics may be set according to the type of engine 2, fuel used, operating environment, and the like. .

  Therefore, the engine 2 is not limited to a diesel engine, and various engines such as a gasoline engine can be used.

It is a principal part block diagram of the series type hybrid electric vehicle 1 by which the control apparatus which concerns on one Embodiment of this invention was mounted. It is a figure which shows the relationship between the electric power generation point used with the control apparatus of FIG. 1, and the equal NOx discharge amount line per unit time. It is a figure which shows the relationship between the electric power generation point used with the modification of the control apparatus of FIG. 1, and the equal NOx discharge amount line per unit time.

Explanation of symbols

2 Engine 4 Generator 8 Battery 10 Motor 18 Drive Wheel 20 HEV-ECU (Control Unit)
24 battery ECU (deterioration degree detection means)

Claims (5)

Engine,
A generator driven by the engine;
A battery charged by the output of the generator;
A motor that operates by receiving electric power supplied from the battery and drives the driving wheels of the vehicle;
A deterioration degree detecting means for detecting the deterioration degree of the battery;
As a power generation point that is the operating point of the engine at the time of charging the battery, a basic power generation point is set on the side where the predetermined exhaust gas characteristic of the engine is worse than the optimal operating point, and the output of the generator When charging the battery, the engine is operated at a power generation point shifted from the basic power generation point in a direction in which the exhaust gas characteristics are improved according to the degree of deterioration of the battery detected by the deterioration degree detecting means. And a control device for the hybrid electric vehicle.   2. The control apparatus for a hybrid electric vehicle according to claim 1, wherein the control means shifts the power generation point while maintaining the output of the engine substantially constant.   The control device for a hybrid electric vehicle according to claim 1, wherein the deterioration degree detecting means detects an internal resistance of the battery as the deterioration degree.   The control means sets the basic power generation point on the side where the exhaust gas characteristic of the engine is worse than the best point based on an increase in the internal resistance of the battery during a predetermined usage period of the battery. The control apparatus for a hybrid electric vehicle according to any one of claims 1 to 3. The power generation point is defined by the engine speed and output torque.
5. The control unit according to claim 1, wherein the control unit sets the basic power generation point on the side where the output torque is higher and the engine speed is lower than the point where the exhaust gas characteristic of the engine is optimal. A control apparatus for a hybrid electric vehicle according to claim 1.

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