JP2004116363A - Power control device for parallel hybrid electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to the improvement of exhaust gas characteristics from an engine in a parallel hybrid electric vehicle. <P>SOLUTION: This power control device for the parallel hybrid electric vehicle 40 has a control map 2 specifying the driven state of an engine 12 and a motor 14 according to a required driving torque and engine speed and having a target operating region 54 in which the component amount of prescribed substance included in exhaust gas from the engine 12 is minimized, drives the engine 12 preferentially over the motor 14 and controls to keep the operating state of the engine 12 within the target operating region 54. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power control device in a parallel hybrid electric vehicle in which a drive shaft of an engine and a drive shaft of a motor are mechanically connected.
[0002]
[Prior art]
2. Description of the Related Art In recent years, hybrid electric vehicles (HEV) have been put into practical use from the viewpoints of air pollution prevention and noise reduction.
There are roughly two types of hybrid electric vehicles, a series type and a parallel type.
[0003]
The parallel type is a system in which both the engine and the motor can drive the wheels, and the driving force by the engine and the driving force by the motor can be selectively used according to the situation. Furthermore, in a parallel-type hybrid electric vehicle, it is not necessary to convert mechanical driving force by engine operation into electric driving force, so that engine output can be mechanically transmitted to driving wheels, In an operation region where the engine output is high, traveling using the engine output can be positively performed.
[0004]
In the parallel type, it is possible to drive with only the motor or to assist the operation of the engine with the motor. The driving force of the motor and the driving force of the engine are used in various combinations. The driving efficiency is excellent.
As an example of this, in a parallel-type hybrid vehicle, there is disclosed a technique of running an engine and a motor depending on an operation region with respect to running of only an engine (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-2000-27672
[0006]
[Problems to be solved by the invention]
In a general parallel-type hybrid electric vehicle, the vehicle is driven by an engine driving force (engine torque) output from the engine, and control is performed so that the motor assists the engine driving force, thereby improving the operating efficiency of the engine. Techniques for achieving this are known. That is, the engine operation is assisted by the driving force of the motor so that the engine can be operated at the point where the fuel efficiency of the engine is the best. Naturally, improving fuel efficiency is an important point from an economic point of view and also from an environmental protection point of view.
[0007]
However, in recent years, NOx, HC, CO, CO ₂ It is strongly desired to suppress the amount of components such as PM and PM from the viewpoint of environmental protection. The present invention has been made in view of such a problem, and an object of the present invention is to provide a power control device for a parallel-type hybrid electric vehicle that contributes to improvement in exhaust gas characteristics of an engine.
[0008]
[Means for Solving the Problems]
In the power control apparatus for a parallel hybrid electric vehicle according to the present invention, both the drive shaft of the engine and the drive shaft of the motor are mechanically connected to the drive shaft of the vehicle, and are set based on the driving state of the driver. A power control device for a parallel hybrid electric vehicle that drives at least one of the motor and the engine so as to attain the required drive torque, wherein the drive of the engine and the motor is performed in accordance with the required drive torque and the engine speed. While defining the state, a control map having a target operation region in which the component amount of the predetermined substance contained in the exhaust gas of the engine is equal to or less than the predetermined amount, and the engine is more than the motor so that the required driving torque is obtained. Characterized in that the engine is operated with priority and the operating state of the engine is controlled to be within the target operating range. That.
[0009]
Therefore, it is possible to effectively suppress the predetermined components contained in the exhaust gas by simple engine control.
According to a second aspect of the present invention, in the power control device for a parallel hybrid electric vehicle according to the first aspect, when the required driving torque is larger than a maximum torque in the target operation region, The invention is characterized in that the engine is operated at the maximum torque in the target operation region and the insufficient torque is supplemented by the motor.
[0010]
Therefore, it is possible to reliably respond to the driving (torque) request from the driver by the motor torque or the engine torque, thereby improving the driving performance while effectively suppressing the predetermined components contained in the exhaust gas. Can be contributed to.
According to a third aspect of the present invention, in the power control apparatus for a parallel hybrid electric vehicle according to the first aspect of the present invention, when the required driving torque is smaller than a minimum torque within the target operation region, The engine is operated with a minimum torque in the target operation region, and power is generated by the motor using excess torque.
[0011]
Therefore, the drive (torque) request from the driver can be responded to by the engine torque output from the engine operating in the target operation region, and the battery can be charged by generating the motor using the surplus torque. Therefore, while effectively suppressing the predetermined components contained in the exhaust gas, it is possible to use energy efficiently without energy loss and to contribute to improvement.
[0012]
According to a fourth aspect of the present invention, there is provided the power control device for a parallel hybrid electric vehicle according to the first aspect, wherein the target operation range is such that the component amount of the predetermined substance contained in the exhaust gas of the engine is the minimum. And the target engine torque line is set by defining the engine torque at which the amount of NOx contained in the exhaust gas from the engine becomes minimum in accordance with the engine speed. It is characterized by.
For this reason, it is possible to contribute to the improvement that the amount of NOx contained in the exhaust gas from the engine can be effectively suppressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a power control device for a parallel hybrid electric vehicle according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic block diagram showing a configuration of a power control device in a parallel hybrid electric vehicle according to an embodiment of the present invention, and FIG. 2 is a schematic control showing control contents for power system devices of the hybrid electric vehicle. FIG. 3 is a flowchart showing a control flow for power-system devices of the hybrid electric vehicle.
[0014]
As shown in FIG. 1, a power system device 40 of an HEV vehicle 30 to which the power control device of the present invention is applied includes a diesel engine (engine) 12, a clutch 13, a motor / generator (motor) 14, a transmission 15, It is composed of a battery 16 and an inverter 17.
In the power system equipment 40, a drive shaft (not shown) of the engine 12 and a drive shaft (not shown) of the motor 14 are connected via a clutch 13 so as to be connectable / disconnectable. The transmission 18 is connected to the drive wheels 18 via a transmission 15, and after the driving force of the engine 12 or the motor 14 is appropriately shifted by the transmission 15.
[0015]
The engine 12 is a diesel engine that drives the drive wheels 18 and generates electric power by driving the motor 14 as a generator. After the engine speed is detected by an engine speed sensor (not shown), the result is transmitted to an integrated control unit (ECU) 1 (described later).
[0016]
The clutch 13 is an electromagnetic clutch that disconnects the mechanical connection between the engine 12 and the motor 14, and the operation thereof is controlled by the integrated control unit 1 described later.
The motor 14 functions as an electric motor (motor) or a generator (generator). When the motor 14 functions as an electric motor, the motor 14 is driven by inputting electric power from a battery 16 to be described later. The drive wheels 18 are driven. The motor 14 is capable of running the HEV vehicle 30 by itself, and the motor 14 assists the operation of the engine 12 when the driving force of the engine 12 is transmitted to the drive wheels 18 (assist operation). It is also possible to perform
[0017]
On the other hand, when the motor 14 functions as a generator, a driving force is input from the engine 12 to the motor 14 via the connected clutch 13 to generate a high-voltage (for example, about 600 V) three-phase alternating current. . The high-voltage AC power generated by the motor 14 is converted into DC power by the inverter 17 and charged into the battery 16.
[0018]
Further, the hybrid electric vehicle 30 has a regenerative brake that operates during braking such as when an engine brake is used or when a foot brake (not shown) is used. That is, when the regenerative braking is operated, the kinetic energy due to the rotation of the drive wheels 18 is converted into electric energy (electric power) by the motor 14 functioning as a generator, and then charged into the battery 16 via the inverter 17. Has become.
[0019]
The ECU 1 controls the operation such as whether the motor 14 functions as a motor or a generator.
The transmission 15 changes the driving force generated by the engine 12 or the motor 14 to an appropriate speed and transmits the driving force to the driving wheels 18, and at the time of the above-described regenerative braking operation, sets the rotating force of the driving wheels 18 to an appropriate speed. It functions so that the speed is changed and input to the motor 14. The operation of the transmission 15 is controlled by the ECU 1.
[0020]
The battery 16 is a lithium-ion battery that stores high-voltage (for example, about 600 V) DC power in a chargeable / dischargeable manner, and is electrically connected to the inverter 17.
The inverter 17 is electrically connected between the battery 16 and the motor 14, converts the DC power stored in the battery 16 into AC power, and then sends the AC power to the motor 14, or causes the motor 14 to function as a generator. In this case, the high-voltage AC power generated in this case is converted into DC power, and is then sent to the battery 16 to charge the battery 16. Further, the inverter 17 converts the DC power stored in the battery 16 into AC power and then feeds the AC power to the motor 14 so that the AC power is adjusted to a frequency corresponding to the rotational speed of the motor 14 so that the AC power is adjusted. 14 also has the function of increasing the operating efficiency.
[0021]
Each of the above-described engine 12, clutch 13, motor 14, transmission 15, battery 16, and inverter 17 is electrically connected to the ECU 1 so as to comprehensively control each device. The ECU 1 includes a storage area (not shown) such as a memory and a CPU (not shown), and various information such as a control map (to be described later) shown in FIG. 2 is stored in the storage area. The power system devices 40 are controlled in accordance with the traveling state of the HEV vehicle 30 and the state of the driver's drive request (for example, accelerator opening and governor opening).
[0022]
Then, the CPU of the ECU (power control device) 1 of the present invention controls each device of the power system devices 40 based on the control map shown in FIG.
As shown in FIG. 2, the control map 2 has a vertical axis indicating the driver's driving request (requested driving torque), a horizontal axis indicating the engine speed, and a division into five regions. Have been. Hereinafter, the five regions, that is, the low rotation region 51, the motor drive region 52, the motor power generation region 53, the low NOx emission region (target operation region) 54, and the regeneration region 55 will be described.
[0023]
For example, when the driver depresses the accelerator pedal to start the stopped HEV vehicle 30 and the rotation speed of the engine 12 during idling gradually increases (see the low rotation region 51), the hybrid electric vehicle 30 travels. Is used preferentially by the motor torque of the motor 14. Then, when the required driving torque cannot be satisfied with the motor torque, control using the engine torque from the engine 12 is performed.
[0024]
That is, the low rotation region 51 is a region surrounded by the condition that the engine rotation speed is equal to or lower than the predetermined rotation speed α (for example, 1500 rpm) and the required driving torque is equal to or higher than 0, and is a function of the torque and the engine rotation speed. When a determined point (hereinafter, this value is referred to as “control point” or “operating point”) is in this low rotation region 51, the driver's drive request is given priority over the motor torque output from the motor 14. It is achieved by gaining. If the required drive torque cannot be achieved even with the maximum motor torque, control is performed to achieve the required drive torque by supplementarily using the engine torque output by the engine 12.
[0025]
Thereafter, when the control point is in a state where the rotation speed of the engine 12 increases to become higher than the predetermined rotation speed α and the driver depresses the accelerator pedal to some extent (see the NOx low emission region 54), Control is performed so that all the torque used for traveling is obtained from the engine torque by the engine 12.
That is, the NOx low emission region 54 is set as a region where the component amount of the predetermined substance (here, NOx) is less than or equal to the predetermined amount based on the target engine torque line T where the component amount of the predetermined substance is the lowest. If the control point is within the target operation area 54 and is an area experimentally obtained based on predetermined driving conditions of the electric vehicle 30, all of the driving torque required by the driver is determined by the engine 12. It is controlled so as to obtain from the engine torque.
[0026]
In this case, the motor 14 only functions as a mere shaft for transmitting the driving force from the engine 12 input via the clutch 13 to the transmission 15. Such a state of the motor 14 is hereinafter referred to as "idling" or "idling state". That is, the idle motor 14 does not function as a motor or a generator.
[0027]
Here, the reason why control is performed so that the vehicle runs with only the driving force of the engine 12 when the control point is in the target operation area 54 will be described. The required drive torque can be satisfied only by the engine torque of the engine 12, and when the engine 12 is operated in this region, the amount of NOx component contained in the exhaust gas from the engine 12 can be satisfied under a predetermined condition (for example, (10.15 mode).
[0028]
Hereinafter, a method of setting the target operation area 54 will be described. The target operating region 54 is calculated by an experiment based on a target engine torque line (minimum operating curve of NOx emission amount) T, the amount of NOx contained in the exhaust gas of the engine, and the running conditions of the hybrid electric vehicle 30. , The NOx emission minimum operation curve T is a line connecting the points at which the torque at which the NOx component amount contained in the exhaust gas from the engine 12 is minimized at each rotational speed of the engine 12 is unambiguous through experiments and the like. It is a curve that can be obtained in a typical manner.
[0029]
That is, theoretically, if the engine 12 is operated along the NOx emission minimum operation curve T, the amount of NOx component contained in the exhaust gas from the engine 12 can be reduced most. When the control point (operating point) exceeds the NOx emission minimum operation curve T (when the required driving torque cannot be satisfied only by the driving force of the engine 12 operating on the NOx emission minimum operation curve T) The motor 14 functions as an electric motor to assist the operation of the engine 12 to correct the actual engine torque so as to follow the NOx emission minimum operation curve T, while the control point falls below the NOx emission minimum operation curve T. (If the driving force of the engine 12 operating with the NOx emission minimum operation curve T alone exceeds the required driving torque), the motor 12 functions as a generator to apply a load to the engine 12, By performing control to correct the actual engine torque so as to follow the NOx emission minimum operation curve T, theoretically, the NOx contained in the engine exhaust gas is reduced. It should be able to most reduced.
[0030]
However, when an experiment is performed to drive the HEV vehicle 30 so that the engine 12 follows the NOx emission minimum operation curve T under predetermined driving conditions that simulate actual driving or actual driving such as the 10.15 mode, It was found that a larger amount of NOx than the theoretical value was contained in the exhaust gas.
This is because when the operation state of the engine 12 is controlled so as to accurately follow the NOx emission minimum operation curve T, the motor 14 frequently operates as a motor or a generator, so that the number of times power is transferred into and out of the battery 16 and the inverter 17 is increased. Is excessive, which results in an increase in electrical loss. In this case, efficiency is degraded, and the merit of operating with the NOx emission minimum operation curve is lost.
[0031]
That is, when the motor 14 functions as an electric motor, the electric power stored in the battery 16 is consumed by being supplied to the motor 14 via the inverter 17. On the other hand, when the motor 14 functions as a generator, The electric power generated by the motor 14 as a generator is supplied to the battery 16 via the inverter 17 to be charged, but the motor 14 as the generator has the same amount of electric power as the electric power used. Even if power is generated, an input / output loss of the power in the inverter 17 and the battery 16 occurs, and it is necessary to drive the engine by this loss to compensate for the power.
[0032]
For this reason, if the NOx emission minimum operation curve T is set as the operation target of the engine 12, a situation occurs in which the NOx emission is not significantly reduced when the HEV vehicle 30 actually runs.
Therefore, in the present invention, a low NOx emission region (target operation region) 54 is set in the control map 2 so that even if the control point of the engine 20 deviates from the NOx emission minimal operation curve T, the NOx low emission region 54 is set within the NOx low emission region 54. If there is, the control is performed such that the driving request of the driver is satisfied only by the engine torque by controlling the operation of the engine 14 without using the motor torque by the motor 14.
[0033]
When the required drive torque is larger than the NOx low emission area 54 (see the motor drive area 52), the maximum torque of the NOx low emission area 54 according to the rotation speed of the engine 12 at that time (hereinafter, “maximum target engine”) The control is performed such that the engine 12 is operated with the torque, and the torque that does not reach the required driving torque is compensated by the motor torque by the motor 14.
[0034]
That is, the motor drive region 52 is defined under the condition that the engine speed is higher than the predetermined speed and the required drive torque is equal to or greater than the target maximum engine torque which is the maximum torque of the target operation region 54. In the motor drive region 52, it is specified that control is performed such that the drive torque requested by the driver is obtained preferentially from the torque of the engine 12 driven at the target maximum engine torque. Have been. In addition, it is stipulated that, when the required driving torque cannot be achieved with the target maximum engine torque, control for operating the motor 14 is performed so as to appropriately obtain the motor torque.
[0035]
On the other hand, when the required driving torque is smaller than the NOx low emission area 54 (see the motor power generation area 53), the minimum torque of the NOx low emission area 54 according to the rotation speed of the engine 12 at that time (hereinafter, “minimum target engine”) The required drive torque is satisfied by operating the engine 12 with the torque, and the surplus torque generated at that time is consumed by the motor 14 functioning as a generator to generate electric power and charge the battery 16.
[0036]
That is, the motor power generation region 53 is a region defined under the condition that the engine speed is operated at the predetermined rotation speed α or more and the torque is less than the minimum engine torque of the target operation region 54. In, the control is performed so that the driving torque required by the driver is obtained from the torque by the engine 12 operating at the minimum target engine torque which is the minimum torque in the target operation area. In addition, when this control is performed, the minimum target engine torque actually output from the engine 12 becomes larger than the required drive torque desired by the driver. In this case, the required minimum engine torque is calculated from the required drive torque. Is applied to the motor 14 by a surplus torque (hereinafter, referred to as “power generation driving torque”) calculated by subtracting the power from the motor 14 to operate the motor 14 as a generator. The electric power generated by this surplus torque is stored in the battery 16 via the inverter 17.
[0037]
Further, when the driver releases the accelerator pedal to use the engine brake or performs a braking operation by using a foot brake or the like (see the braking area 55), the motor 14 functions as a regenerative brake, The hybrid electric vehicle 30 is braked and generates power.
That is, the regenerative region 55 is a region defined under the condition that the required drive torque is less than 0 (that is, during braking) regardless of the engine speed, and the kinetic energy of the traveling HEV vehicle 30 is used as a generator. Control is performed such that the electric power is converted into electric energy (electric power) by the functioning motor 14 and the electric power is stored in the battery 16 via the inverter 17. At this time, the engine 12 performs the fuel-free injection operation.
[0038]
Since the power control device for a parallel hybrid electric vehicle as one embodiment of the present invention is configured as described above, control is executed according to, for example, a flowchart shown in FIG.
First, in step A1, it is determined whether the required driving torque is equal to or greater than zero. If the required driving force is equal to or greater than zero, the process proceeds along the yes route to reach step A2, while if the required driving force is less than zero, the process proceeds along the no route and reaches step A7.
[0039]
In step A7, regenerative control is performed. The regenerative control is control defined by a regenerative area 55 of the control map 2 shown in FIG. 2, and the kinetic energy of the traveling HEV vehicle 30 is converted into electric energy (electric power) by the motor 14 functioning as a generator. The power is converted and stored in the battery 16 via the inverter 17.
[0040]
On the other hand, in step A2, it is determined whether or not the rotation speed of engine 12 is greater than α rpm. Here, if the engine speed is higher than α rpm, the operation proceeds along the yes route to reach step A3, while if the engine speed is equal to or lower than α rpm, the operation proceeds along the no route and reaches step A10.
In step A10, it is determined whether the required drive torque is greater than the maximum motor torque. If the required drive torque is smaller than the maximum motor torque, the vehicle travels through the no route to reach step A14, while if the required drive torque is greater than the motor maximum torque, it travels from the step 10 through the yes route to reach step A11. .
[0041]
In step A14, the motor 14 is controlled such that the motor torque becomes the required drive torque, and the hybrid electric vehicle 30 travels. In this case, the engine 12 is maintained in the no-load operation state because the operating range is such that the amount of NOx contained in the exhaust gas of the engine 12 is relatively large.
On the other hand, in step A11, the required driving torque of the driver exceeds the motor maximum torque, which is the maximum torque that can be output by the motor 14, and therefore, the difference torque that does not reach the required driving torque at the motor maximum torque (ie, , Insufficient torque) by the engine 12. That is, in this case, the control is executed so as to satisfy the required driving torque by the motor maximum torque + engine torque.
[0042]
The control in steps A10, A11, and A14 is control defined in the low rotation region 51 of the control map shown in FIG.
When the process proceeds from step A2 to step A3, it is determined whether the required drive torque is within the target operation region 54 shown in FIG. When the target drive torque is within the target operation area 54, the vehicle travels along the yes route to reach step A8. Conversely, when the target drive torque is not within the target operation area 54, the vehicle travels along the no route. It reaches step A4.
[0043]
In step A8, only the engine 12 is operated to achieve the required driving torque, and the motor 14 is not operated. The control in step A8 is control specified in the target operation area 54 shown in FIG.
On the other hand, when the process proceeds from step A3 to step A4, it is determined whether the required drive torque is greater than the maximum target engine torque (the boundary between the target operation area 54 and the motor drive area 52 in FIG. 2). If the required drive torque is larger than the maximum target engine torque, the vehicle travels through the yes route to reach step A5. If the required drive torque is equal to or less than the maximum target engine torque, it travels through the no route and reaches step A12.
[0044]
In step A12, the minimum torque in the target operation area 54 (minimum target engine torque; the boundary between the target operation area 54 and the motor power generation area 53 in FIG. 2) and the motor when the motor 14 functions as a generator It is determined whether or not the sum of the torque at the time of the maximum load (the maximum power generation load) is smaller than the required drive torque. That is, it is determined whether the following expression (1) is satisfied.
[0045]
Required drive torque <minimum target engine torque + maximum power generation load (torque) (1)
Note that the maximum power generation load is a negative value because it is a value indicating that the engine 12 consumes the engine torque.
Then, if the equation (1) is satisfied, the system proceeds along the yes route to reach step A13. On the other hand, if the equation (1) is not satisfied, the system proceeds along the no route and reaches step A15.
[0046]
Here, when the process proceeds to step A13, the required driving torque is further reduced even if the maximum power generation load is added to the minimum target engine torque. Therefore, in step A13, an instruction to operate the motor 14 as a generator at the maximum power generation load is given, and the engine 12 is operated at a torque equal to or lower than the minimum target engine torque so as to attain the required driving torque.
[0047]
When the control in step A13 is performed, the operating point of the engine 12 is outside the target operating area 54. However, the control is performed such that the engine output from the engine 12 is suppressed after the power generation load of the motor 14 is maximized. Therefore, the amount by which the operating point of the engine 12 deviates from the target operating area 54 can be minimized.
[0048]
When the process proceeds to step A15, control is performed such that the required drive torque is obtained by variably applying a load for power generation by the motor 14 to the minimum target engine torque.
That is, in the control in step A15, since the engine 12 is operated in the target operation area 54, the engine 12 is calculated by subtracting the minimum target engine torque from the required drive torque while suppressing the NOx emission to the minimum required. Since the surplus torque to be generated can be diverted to the power generation by the motor 14, the amount of NOx contained in the exhaust gas from the engine 12 can be reduced, and charging can be performed with high efficiency. Note that the above control in step A13 and step A15 corresponds to control in the motor power generation region 53 of the control map 2 shown in FIG.
[0049]
On the other hand, when the process proceeds from step A4 to step A5, the required drive torque is larger than the sum of the target maximum torque according to the rotation speed in the target operation region 54 and the maximum torque of the motor 14 (maximum motor torque). Is determined by the following equation (2).
Required drive torque> Maximum target engine torque + Maximum motor torque (2)
That is, the engine 12 is operated at the maximum target engine torque, and it is determined whether or not the required drive torque can be achieved by further adding the motor torque by the motor 14 to the maximum target engine torque. It is.
[0050]
In step A5, if the above equation (2) does not hold, the process proceeds along the no route to step A9. On the other hand, if the above equation (2) does not hold, the yes route goes to A6.
In step A9, the engine 12 is operated at the maximum target engine torque, and control is performed to compensate for the torque less than the required drive torque by the motor torque at the maximum target engine torque.
[0051]
On the other hand, in step A6, since the required drive torque cannot be obtained even if the maximum motor torque is added to the maximum target engine torque, in this case, the maximum motor torque is output from the motor 14, and the required drive torque cannot be satisfied. The required drive torque is obtained by controlling the engine 12 so that the torque is supplemented by the engine torque. Also, in this case, the operating point of the engine 12 deviates from the target operating area 54. However, since the motor torque by the motor is used to the maximum, the amount by which the operating point of the engine 12 deviates from the target operating area 54 is , Can be minimized. Note that the control in steps A6 and A9 described above corresponds to the control set in the motor drive area 52 in the control map 2 in FIG.
[0052]
As described above, in the present invention, by operating the engine 12 as much as possible with a torque that minimizes the component amount of the predetermined substance contained in the exhaust gas from the engine 12, the predetermined component amount contained in the exhaust gas can be reduced. Becomes possible.
It should be noted that the present invention is not limited to the above-described embodiment and its modifications, and can be implemented with various modifications without departing from the spirit of the present invention.
[0053]
For example, in the above embodiment, the clutch 63 is described as an electromagnetic clutch, but may be a fluid clutch or a friction clutch. Here, when a friction clutch is used as the clutch 63, it may be a single-plate type or a double-plate type, and may be either dry or wet.
Further, although the battery 71 has been described as a lithium ion battery, it may be a nickel metal hydride battery or a lead battery.
[0054]
Further, in the above-described embodiment, the case where the engine 62 is a diesel engine has been described. However, an engine other than the diesel engine, for example, a gasoline engine or a gas turbine engine may be used. The present invention has a particularly great effect when a diesel engine is used.
[0055]
That is, when purifying exhaust gas components of a diesel engine, it is difficult to use an exhaust gas purification device represented by a three-way catalyst in terms of engine characteristics. Therefore, the amount of components such as NOx and HC contained in exhaust gas is reduced by the engine. It is very preferable to apply the present invention, which can suppress the air burned in the exhaust gas from the engine when the air is exhausted from the engine. The reason will be described below.
[0056]
In an exhaust gas purification system of a gasoline engine, a so-called three-way catalyst capable of simultaneously purifying three types of exhaust gas substances, that is, carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) in exhaust gas, is used. A so-called shaping device is attached to the exhaust pipe so that the exhaust gas can be purified only when the fuel burns near the stoichiometric air-fuel ratio.
[0057]
That is, in the purification by the three-way catalyst, first, when exhaust gas containing CO, HC, and NOx burned near the stoichiometric air-fuel ratio is input to the three-way catalyst, the three-way catalyst removes O from NOx. , CO and HC are oxidized by the removed O, so that NOx is reduced to N ₂ And CO and HC are CO ₂ And H ₂ O.
However, since diesel engines burn light oil in an excess air (oxygen) state, there is an excess of oxygen in exhaust gas, and it is difficult to purify NOx even with a three-way catalyst.
[0058]
In addition, if a lean catalyst is used, it is possible in principle to remove NOx from exhaust gas containing too much oxygen, but in the first place the catalyst is weak against sulfur and is used in diesel engines that use light oil containing a large amount of sulfur as fuel. Is difficult to use a lean catalyst.
As described above, since it is difficult to purify exhaust gas in an exhaust system of a diesel engine, exhaust gas substances are already suppressed when exhaust gas is released from the engine.
[0059]
In general, the operating point at which fuel consumption is high and the operating point at which NOx is low or the operating point at which HC is low are often not the same. Even if the control device of the present invention is applied after using it as an engine to perform control to suppress exhaust gas components (for example, NOx), the diesel engine has good fuel efficiency in almost all operating ranges, and the operating point is slightly increased. Since the shift does not significantly affect the fuel efficiency, it is possible to achieve both effects of suppressing exhaust gas components and improving fuel efficiency.
[0060]
【The invention's effect】
As described in detail above, according to the power control apparatus for a parallel hybrid electric vehicle of the present invention, the control map is set based on the engine torque line at which the component amount of the predetermined substance contained in the exhaust gas of the engine becomes minimum. The target operation region in which the component amount of the predetermined substance is set to be equal to or less than the predetermined amount is set, and control can be performed such that the operation state of the engine falls within the target operation region. (Claim 1).
[0061]
When the driving torque required by the driver is larger than the maximum torque in the target operation area, the engine is operated at the maximum torque in the target operation area and the motor is used to compensate for the insufficient torque. The driving force (torque) required by the driver can be reliably transmitted to the driving wheels by the motor torque and the engine torque while effectively suppressing the predetermined component, thereby contributing to an improvement in driving performance. .
[0062]
Further, when the required driving torque is smaller than the minimum torque in the target operation region, the engine is operated at the minimum torque in the target operation region, and control is performed to generate electric power with the motor using the surplus torque. While effectively suppressing the components, the driving force (torque) required by the driver is surely secured by the engine torque, and the motor can be generated by the surplus torque, so that the battery can be charged. Therefore, it is possible to use energy efficiently without wasting energy (claim 3).
[0063]
Further, the target operation region is set based on the target engine torque line in which the component amount of the predetermined substance contained in the exhaust gas of the engine is the lowest, and the target engine torque line is such that the NOx amount contained in the exhaust gas from the engine is the lowest. Since the engine torque is set by defining it according to the engine speed, the amount of NOx contained in the exhaust gas from the engine can be effectively suppressed (claim 4).
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a configuration of a power control device in a parallel hybrid electric vehicle according to an embodiment of the present invention.
FIG. 2
5 is a schematic control map showing control contents for power system devices of the hybrid electric vehicle in the parallel hybrid electric vehicle according to one embodiment of the present invention.
FIG. 3
5 is a flowchart illustrating a control flow for power system devices of the hybrid electric vehicle.
[Explanation of symbols]
1 Integrated control unit (ECU)
2 Control map
12 Engine
14 Motor (motor / generator)
30 Hybrid electric vehicle (vehicle)
54 NOx low emission area (target operation area)

Claims (4)

The drive shaft of the engine and the drive shaft of the motor are both mechanically connected to the drive shaft of the vehicle, and drive at least one of the motor and the engine such that the required drive torque is set based on the driving state of the driver. In a power control device for a parallel hybrid electric vehicle,
A control having a target operating region in which the driving state of the engine and the motor is defined according to the required driving torque and the engine speed, and the component amount of a predetermined substance contained in exhaust gas of the engine is equal to or less than a predetermined amount. Maps and
A parallel hybrid electric machine, wherein the engine is operated with a higher priority than the motor so that the required drive torque is obtained, and the operating state of the engine is controlled so as to be within the target operation range. Power control device for automobile. 2. The system according to claim 1, wherein when the required driving torque is larger than the maximum torque in the target operation region, the engine is operated at the maximum torque in the target operation region, and the insufficient torque is supplemented by the motor. A power control device for the parallel hybrid electric vehicle according to the above. When the required driving torque is smaller than the minimum torque in the target operation region, the engine is operated with the minimum torque in the target operation region, and power is generated by the motor using excess torque. A power control device for a parallel hybrid electric vehicle according to claim 1. The target operation region is set based on a target engine torque line in which the component amount of the predetermined substance contained in the exhaust gas of the engine is the minimum,
2. The parallel engine according to claim 1, wherein the target engine torque line is set by defining an engine torque that minimizes the amount of NOx contained in exhaust gas from the engine according to the engine speed. 3. Power control device for hybrid electric vehicles.

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