JP2004116362A - Power control device for parallel hybrid electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress prescribed substance included in exhaust gas from an engine in a parallel hybrid electric vehicle. <P>SOLUTION: This power control device for a parallel hybrid electric vehicle 40 comprises a required driving torque setting means 56 for setting a required driving torque to driving wheels 67 based on the driving state of a driver; a plurality of driving characteristic setting maps 58, 58a, 58b setting the operating state of an engine 62 and a motor 64 according to the required driving torque set by the required driving torque setting means 56; an engine speed detecting means 69 for detecting the rotating speed of the engine 62; and a map selecting means 57 for selecting the maps 58, 58a, 58b according to the engine speed detected by the engine speed detecting means 69. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to 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]
In recent years, it has been strongly desired to suppress various substances contained in exhaust gas of an engine (hereinafter, referred to as “exhaust gas substances”). Although this exhaust gas substance differs depending on the type of engine, for example, carbon dioxide (CO ₂ ), Carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter (PM).
[0003]
It is known that these various types of exhaust gas substances can be suppressed by controlling the operating point (for example, torque and rotation speed) of the engine. However, usually, the engine of an automobile keeps the operating point constant. It is difficult to control the exhaust gas component at the operating point of the engine because the torque and the rotation speed change every moment instead of the steady operation.
[0004]
[Problems to be solved by the invention]
On the other hand, from the viewpoint of air pollution prevention and noise reduction, technology related to a hybrid electric vehicle (HEV) has attracted attention and has been put to practical use.
The HEV method is roughly classified into two types, a series type and a parallel type.
[0005]
Of these, the parallel type is a system in which both the engine and the motor are mechanically connected to the driving wheels, and both can drive the driving wheels. It can be used properly according to the driving request (driving state) by the driver.
Further, such a parallel type hybrid electric vehicle also has a technology for switching between a map for driving the vehicle motor to generate power from the engine speed and the load and a map for driving and driving the vehicle motor. (For example, see Patent Document 1).
[0006]
However, such a map region does not always coincide with an engine operation region in which the emission of exhaust gas substances (for example, HC) can be suppressed. Therefore, in the parallel type HEV, exhaust gas substances such as NOx and HC contained in exhaust gas from the engine are used. There is room for further control of the emission of carbon dioxide.
[0007]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a parallel hybrid electric vehicle that can suppress a predetermined substance contained in exhaust gas from an engine.
[0008]
[Patent Document 1] JP-A-2001-314003
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a power control apparatus for a parallel hybrid electric vehicle, wherein a drive shaft of an engine and a drive shaft of a motor are both mechanically connected to drive wheels of the vehicle. In the control device, a required drive torque setting means for setting a required drive torque for the drive wheel based on a driving state of the driver, and a request drive torque of the engine and the motor in accordance with the required drive torque set by the required drive torque setting means A plurality of operating characteristic setting maps for setting an operating state, an engine speed detecting means for detecting the engine speed, and an engine speed detected by the engine speed detecting means are included in exhaust gas from the engine. The amount of the specified substance contained in the exhaust gas from the engine is lower than that in the low rotation range where the amount of the specified substance is relatively large. Depending on the case of the target small high rpm, it is characterized in that it includes a map selecting means for selecting one of the maps from the operating characteristic setting map the plurality of.
[0010]
Therefore, energy loss can be suppressed, efficient traveling can be performed, and the amount of the component of the predetermined substance contained in the exhaust gas can be effectively suppressed.
According to a second aspect of the present invention, in the power control device for a parallel hybrid electric vehicle, the driving characteristic setting map may include a control map for a low rotation range and a control map for a high rotation range of the engine. The map selection means selects a low rotation speed control map when the engine rotation speed is less than a predetermined rotation speed, and selects a high rotation speed control map when the engine rotation speed is equal to or higher than the predetermined rotation speed. Selecting a map, wherein the low-revolution-range control map is set so that the required drive torque for the drive wheels is obtained in preference to the motor torque of the motor over the engine torque of the engine. I have.
[0011]
Therefore, it is possible to appropriately transmit the driving force according to the engine speed to the driving wheels, which can also contribute to the improvement that can be achieved with a simple configuration.
According to a third aspect of the present invention, there is provided a power control device for a parallel hybrid electric vehicle according to the first or the second aspect, wherein a battery for supplying power to the motor and a remaining power for detecting a remaining power of the battery are provided. The operating characteristic setting map includes a capacity detection unit, and the operating characteristic setting map is configured to output the engine and the engine in accordance with the remaining power detected by the remaining power detection unit and the required driving torque set by the required driving torque setting unit. The driving state of the motor is set.
[0012]
Therefore, it is possible to drive the hybrid electric vehicle with high efficiency while keeping the SOC at an appropriate level.
According to a fourth aspect of the present invention, there is provided the power control apparatus for a parallel hybrid electric vehicle according to the second to third aspects, wherein a component of a predetermined substance contained in exhaust gas from the engine in the range of the predetermined rotation speed or more. Storage means for storing, for each of the engine rotation speeds, the engine torque having the lowest amount and holding it as a target engine torque, wherein the high rotation speed control map stores the engine in accordance with the target engine torque; The engine is operated preferentially, and if the required drive torque set by the required drive torque setting means is larger than the target engine torque, the motor is driven to compensate for the insufficient torque. If the required drive torque set by the required drive torque setting means is smaller than the target engine torque, the motor is used as a generator. Is actuated, characterized by using a power surplus torque.
[0013]
For this reason, it is possible to effectively suppress the component amount of the predetermined substance in the exhaust gas, and it is possible to suppress the energy loss while reliably fulfilling the driving demand of the driver.
[0014]
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. 1 to 4. FIG. 1 is a schematic block diagram showing a main configuration thereof, and FIG. FIG. 3 is a graph showing an operating state of the engine, showing a torque distribution control map switching rotational speed α, and FIG. 3 is a schematic diagram of a driving characteristic setting map for controlling a driving force source of the HEV vehicle. FIG. 4 is a diagram showing a case where the engine speed is in a low speed rotation region, and FIG. 4 is a schematic diagram of a driving characteristic setting map for controlling a driving force source of the HEV vehicle, showing a case where the engine speed is in a high speed rotation region. .
[0015]
As shown in FIG. 1, a parallel hybrid electric vehicle 40 according to one embodiment of the present invention mainly includes an integrated control unit (power control device; ECU) 50, an engine 62, a clutch 63, a motor 64, and a transmission 65. , A battery 71 and an inverter 72. Hereinafter, these devices will be briefly described.
The engine 62 is a diesel engine, and its drive shaft (not shown) is mechanically connected to drive wheels 67 via a clutch 63, a motor 64, a transmission 65, and a propeller shaft (drive shaft for drive wheels) 66. The HEV vehicle 40 is driven by driving the drive wheels 67 by the engine driving force generated by the engine 62.
[0016]
When the motor 64 functions as a generator, the engine 62 serves as a driving force source of the motor 64 to generate high-voltage (for example, about 300 V) AC power.
The engine 62 is electrically connected to an accelerator opening sensor 68 that detects the amount of depression of an accelerator pedal 61 that is depressed in response to a driver's drive request and transmits the detection result to the ECU 50. Further, the engine 62 is provided with an engine speed sensor (engine speed detecting means) 69 for measuring the speed Ne of the engine drive shaft.
[0017]
The clutch 63 is an electromagnetic clutch which disconnects the mechanical connection between the engine 62 and the motor 64, and its operation is controlled by an ECU 50 described later.
The motor 64 obtains electric power from a battery 71 described later via an inverter 72, functions as an electric motor (motor), and drives the drive wheels 67.
[0018]
On the other hand, when the motor 64 functions as a generator, the engine driving force is input to the motor 64 via the clutch 63. At this time, the motor 64 generates high-voltage (for example, about 300 V) AC power. The high-voltage AC power is stored in the battery 71 after being converted into DC power by the inverter 72.
Further, the motor 64 operates as a generator also at the time of regenerative braking such as braking of the vehicle. In this case, the motor 64 functioning as a generator generates kinetic energy due to rotation of the drive wheels 67. After being converted into electric energy (electric power), it is stored in a battery 71 via an inverter 72. The operation control such as whether the motor 64 functions as an electric motor or a generator is performed by the ECU 50.
[0019]
The transmission 65 appropriately transmits the rotation speed of a motor drive shaft (not shown) driven by the driving force of the engine 62 or the driving force of the motor 64 to the driving wheels 67. In addition, during the regenerative braking operation, the transmission 65 inputs the rotation of the propeller shaft 66, which is rotated by the rotation (kinetic energy) of the driving wheel 67, to the motor 64 after appropriately changing the speed. The operation of the transmission 65 is controlled by the ECU 50.
[0020]
The battery 71 is electrically connected to the inverter 72 to enable charging and discharging of high-voltage (for example, about 300 V) DC power. Further, the battery 71 is provided with a power sensor (power remaining capacity detecting means) 73 for measuring the remaining power amount stored in the battery 71.
The inverter 72 is electrically interposed between the battery 71 and the motor 64, converts DC power stored in the battery 71 into AC power, and sends the AC power to the motor 64, or causes the motor 64 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 71 to charge the battery 71. Further, the inverter 72 converts the DC power stored in the battery 71 into AC power and then feeds the AC power to the motor 64 so that the AC power is adjusted to a frequency corresponding to the rotation speed of the motor 64 so that the AC power is adjusted. It also has a function to increase the operating efficiency of the 64.
[0021]
The ECU 50 is electrically connected to each of the accelerator opening sensor 68, the engine speed sensor 69, the engine 62, the clutch 63, the motor 64, the transmission 65, the battery 71, and the inverter 72, and integrates each device. It is for controlling, and mainly comprises a memory (storage means) 51 and a CPU (not shown).
[0022]
The memory 51 includes a required torque setting means 56 realized by software, a map selector (map selection means) 57, two operation characteristic setting maps 58a and 58b, and a target engine torque T. _e Is stored.
The required driving torque setting means 56 is configured to determine the required driving torque (hereinafter referred to as “required driving torque”) based on the depression of the accelerator pedal 61 and the engine speed detected by the accelerator opening sensor 68. ) Is calculated and set.
[0023]
The map selector 57 selects a control map corresponding to the engine speed Ne detected by the engine speed detecting means 69 from the plurality of control maps 58a and 58b held in the memory 51.
The operation characteristic setting map 58 includes a low rotation speed control map 58a used when the engine 62 is operated in a low rotation speed range (for example, from idle speed to less than 1500 rpm) and a high rotation speed control range (for example, (1500 rpm or more), which is used when the engine is operated at a high speed range, and is appropriately selected by the map selector 57.
[0024]
Here, switching between these two maps will be described with reference to FIG.
In the graph showing the engine operation state shown in FIG. 2, the vertical axis represents the engine torque, the horizontal axis represents the engine speed, and the region where the speed is lower than the control map switching speed α is set as the low speed region A. In addition, a region where the rotation speed is higher than the control map switching rotation speed α is set as the high rotation region B, and when the engine 62 is operating in the low rotation region A, the control for the low rotation region is performed. While the control for realizing the required driving torque is performed using the map 58a, when the engine 62 is operating in the high rotation region B, the driving torque is reduced using the high rotation region control map 58b. Control. It should be noted that the low-speed range control map 58a and the high-speed range control map 58b may be collectively referred to as an "operating characteristic setting map 58", and the operating characteristic setting map 58 is described in FIGS. 4 will be described later in detail.
[0025]
Target engine torque T _e Is a set value obtained by connecting points obtained by measuring and plotting the torque at which the amount of NOx contained in the exhaust gas from the engine 62 becomes minimum at each rotation speed by a line.
That is, the target engine torque T _e , The amount of NOx contained in the exhaust gas from the engine 62 can be greatly reduced.
[0026]
By the way, in the graph shown in FIG. _e Is not set. This is because, in the engine speed range below the torque distribution control map switching speed α (that is, in the low speed region A), the minimum amount of NOx contained in the exhaust gas from the engine 62 is determined by the torque distribution control map switching speed. This is because the number is much larger than when the operation is performed at α or more (that is, in the high rotation region B). In other words, even if the engine 62 is operated with the torque that minimizes NOx in the low rotation region A, the effect of suppressing the amount of NOx contained in the exhaust gas from the engine 62 is not so significant. Therefore, in the low rotation region A, the required driving torque is mainly realized by the motor 64 instead of controlling the torque of the engine 62 and the operation of the engine 62 is stopped as much as possible, so that the exhaust gas from the engine 62 is included. The NOx amount is suppressed.
[0027]
On the other hand, in the region above the torque distribution control map switching rotational speed α (that is, the high rotational region B), the target engine torque T _e Operating the engine 62 along the characteristic line is effective in reducing the amount of NOx contained in the exhaust gas from the engine 62. In this case, control is performed so that the required driving torque is mainly realized by the engine 62. Thus, the amount of NOx contained in the exhaust gas from the engine 62 is suppressed.
[0028]
Next, an operation characteristic setting map 58 used when controlling the driving state of the engine 62 and the motor 64 paying attention to the above-mentioned suppression of the amount of NOx in the exhaust gas will be described.
First, the low-speed rotation range control map 58a will be described with reference to FIG.
As shown in FIG. 3, in the low-rotational-range control map 58a, the required driving torque is set on the vertical axis, the remaining power (SOC) in the battery 71 is set on the horizontal axis, and the lower limit SOC and the target SOC are set on the horizontal axis. Each of the SOC and the upper limit SOC is set.
[0029]
The lower limit SOC is a value determined in advance that if the amount of power stored in the battery 71 further decreases, the power required to drive the motor 64 may be insufficient. This is the charged amount near 45% when the full charge is 100%.
The target SOC is a value determined in advance that the amount of charge in the battery 71 is optimal, and is, for example, a value near 50% of the amount of charge.
[0030]
The upper limit SOC is a value that is determined in advance as a possibility that the battery 71 may be in an overcharged state when the charged amount in the battery 71 is further increased. Value.
In addition, the area of the control map 58a for the low rotation range is divided into a first area 1, a second area 2, a third area 3, a fourth area 4, a fifth area 5, and a sixth area 6. Hereinafter, a value determined by the required driving torque set by the depression amount of the accelerator pedal 61 and the rotation speed of the engine 62 and the SOC of the battery 71 will be described as a “control point”.
[0031]
The low rotation speed control map 58a is a map used when the engine is operating at a low rotation speed in the low rotation speed region A (that is, when the engine speed is low rotation speed).
In the low-revolution-range control map 58a, the amount of NOx contained in the exhaust gas from the engine operating at low rotation becomes large, so that the operation of the engine 62 is suppressed while the motor drive by the motor 64 is performed as much as possible. The control for running the HEV vehicle 40 using the force is set.
[0032]
That is, as shown in the low-speed range map 58a of FIG. 3, when the electric power is sufficiently stored (that is, the battery SOC is equal to or higher than the target SOC) and the driver's required driving torque is equal to or less than the motor maximum torque. (Refer to the fifth region 5 and the sixth region 6), only the motor torque is used for traveling, and the engine 62 is controlled to a no-load operation (equivalent to idle). That is, in this case, the driving torque required by the driver is set as in the following equation (1).
[0033]
Required drive torque = Motor torque (1)
If the magnitude of the required driving torque exceeds the motor maximum torque that the motor 64 can output (see the third area 3 and the fourth area 4), the engine 62 is operated to The engine torque compensates for the insufficient torque that cannot be covered by the torque generated by the engine. That is, in this case, the driving torque required by the driver is satisfied as in the following equation (2).
[0034]
Required drive torque = motor maximum torque + engine torque (2)
As described above, by controlling the operating state of the engine 62, the amount of NOx component contained in the exhaust gas from the engine 62 can be suppressed.
When the SOC of the battery 71 becomes equal to or lower than the target SOC (see the second area 2), the operation of the motor 64 is stopped to avoid a decrease in the SOC, and only the engine torque of the engine 62 is used for traveling. Is controlled. In this case, the required drive torque is set as in the following equation (3).
[0035]
Required drive torque = engine torque (3)
When the SOC of the battery 71 has dropped below the lower limit SOC (see the first region 1), the control is executed to operate the motor 64 as a generator and use the engine torque for both traveling and power generation. It is supposed to. In this case, the required driving torque is represented by the following equation (4). The “motor power generation torque” below is a torque consumed when the motor 4 functioning as a generator is driven to generate power, and its value is negative.
[0036]
Required drive torque = engine torque + motor power generation torque (4)
As described above, in the first region 1 and the second region 2, the motor 64 is mainly operated to control the operation of the engine 62 mainly in the low rotation region where the amount of NOx contained in the exhaust gas is relatively large. The NOx emission increases as compared with the operation in the third region 3, the fourth region 4, the fifth region 5, and the sixth region 6, which are temporarily performed until the SOC of the battery 71 recovers. Since the operation is simple, the increase in the NOx emission is also temporary, so that the increase in the NOx emission is suppressed as much as possible.
[0037]
Next, the high rotation range control map 58b will be described with reference to FIG.
This high-speed range control map 58b is a map used when the engine is operating in the high-speed range B (that is, when the engine speed is high).
That is, since the amount of NOx component contained in the exhaust gas from the engine 62 operating at a high speed is basically small, in the high speed range control map 58b, the drive torque by the engine 62 is mainly used. In principle, control for running the HEV vehicle 40 is performed. Specifically, the engine 62 is set to the target engine torque T at which the NOx emission is minimized. _e , And the target engine torque T _e The control is performed such that the difference torque between the driving torque desired by the driver and the driver is supplemented by the motor 64 as the electric motor or consumed by the motor 64 as the generator.
[0038]
For example, in the ninth region 9, the engine 62 is set to the target engine torque T _e , And the target engine torque T _e Performs control to compensate for the insufficient torque that cannot cover the required driving torque with the motor torque. In this case, the required driving torque is set as in the following equation (5).
Required drive torque = Target engine torque T _e + Motor torque (5)
Further, for example, in the eleventh region 11 and the twelfth region 12, the engine 62 is set to the target engine torque T. _e , And the target engine torque T _e In, control is performed to consume a torque (excess torque) that becomes excessive than the required driving torque as a torque (motor generation torque) necessary to drive the motor 64 functioning as a generator. In this case, the required driving torque is set as in the following equation (6). As described above, the motor power generation torque is negative.
[0039]
Required drive torque = Target engine torque T _e + Motor generated torque (6)
If the SOC of the battery 71 is lower than the target SOC and the required drive torque is larger than the target engine torque (see the eighth area 8), the operation of the motor 64 is stopped to avoid the decrease in the SOC. Then, the vehicle is controlled so as to run only by the driving torque of the engine 62. In this case, the required driving torque is set as in the following equation (7).
[0040]
Required drive torque = engine torque (7)
When the SOC of the battery 71 has dropped below the lower limit SOC (see the seventh area 7), the motor 64 is operated as a generator, and the driving torque of the engine 62 is used for both traveling and power generation. Control is performed. In this case, the required driving torque is represented by the following equation (8).
[0041]
Required drive torque = engine torque + motor power generation torque (8)
When the SOC of the battery 71 has risen to the upper limit SOC or more (see the tenth region 10 and the thirteenth region 13), the HEV vehicle 40 is controlled to run by the driving torque of the motor 64, and The torque that cannot achieve the required drive torque by the maximum motor drive torque, which is the maximum torque by the motor 64, is compensated for by the engine drive torque by the engine 62.
[0042]
That is, in the tenth region 10, the required driving torque is set by the following equation (9).
Required drive torque = motor maximum torque + engine torque (9)
In the thirteenth region 13, the required driving torque is set by the following equation (10).
[0043]
Required drive torque = Motor torque (10)
Note that, in the thirteenth region 13, the engine 62 is operating under no-load operation.
In the tenth area 10 and the thirteenth area 13, the driving is switched to the driving by the motor 64 because the SOC of the battery 71 has already exceeded the upper limit SOC, and the battery 71 may be in an overcharged state. . Therefore, in the tenth region 10 and the thirteenth region 13, the control for using the motor 64 as the electric motor is preferentially performed so that the SOC of the battery 71 is lower than the upper limit SOC.
[0044]
Further, as described above, in the seventh region 7, the eighth region 8, and the tenth region 10, the engine 62 is supplied with the target engine torque T. _e In order to perform the control of operating in the ninth region 9, the eleventh region 11, and the twelfth region 12, the NOx emission amount increases as compared with the operation in the ninth region 9, the eleventh region 11, and the twelfth region 12. This is a temporary operation until the SOC of the battery 71 is optimized, and an increase in NOx emission is suppressed as much as possible.
[0045]
Since the power control device for a parallel hybrid electric vehicle as one embodiment of the present invention is configured as described above, the following operations and effects can be obtained.
First, the required torque setting means 56 calculates the required driving torque for the HEV vehicle 40 based on the accelerator opening information from the accelerator opening sensor 68 and the engine speed information Ne from the engine speed detecting means 69.
[0046]
Then, based on information from the engine speed detecting means 69, the map selector 57 selects one of the plurality of operating characteristic setting maps 58 according to the engine speed Ne of the engine 62 obtained from the engine speed detecting means 69. Select a control map. Here, if the rotation speed of the engine 62 is less than the control map switching rotation speed α (for example, 1500 rpm), the low rotation range control map 58a shown in FIG. 3 is selected, while the rotation speed of the engine 62 is controlled by the control map. If it is equal to or higher than the switching rotation speed α (for example, 1500 rpm), the high rotation range control map 58b shown in FIG. 4 is selected.
[0047]
The ECU 50 controls the inverter 72, the engine 62, the clutch 63, the motor 64, and the transmission 65 based on the selected low rotation speed control map 58a or high rotation speed control map 58b.
Here, the operation of the control based on the low-rotational-region operating characteristic setting map 58a shown in FIG. 3 will be described.
[0048]
When there is a control value in the first area 1 shown in FIG. 3, the ECU 50 shown in FIG. 1 controls the HEV vehicle 40 to use only the driving force by the engine 62 for traveling. More specifically, the clutch 63 is brought into the engaged state, and the engine 62 is controlled according to the required driving torque calculated by the required torque setting means 56 and the rotational speed Ne of the engine 62 detected by the engine rotational speed detecting means 69. And the transmission 65 is controlled to drive the drive wheels 67. At the same time, a command is issued to the motor 64 and the inverter 72 so that the motor 64 functions as a generator, and the motor 64 to which the engine driving force is input is controlled so as to generate high-voltage AC power. I do.
[0049]
In the first region 1, the control to be performed when the SOC is less than the lower limit SOC is set regardless of the required driving torque. That is, in the first region 1, the SOC of the battery 71 is extremely low, and therefore, it is necessary to give the highest priority to charging the battery 71. For this reason, after making the motor 64 function as a generator, the engine driving force of the engine 62 is input to the motor 64, the generated power is stored in the battery 71, and at the same time, the engine driving force is transmitted to the driving wheels 67. The HEV vehicle 40 is controlled to travel.
[0050]
When there is a control value in the second region 2 shown in FIG. 3, the ECU 50 shown in FIG. 1 puts the clutch 63 into the connected state, furthermore, the required drive torque calculated by the required torque setting means 56 and the engine speed detecting means 69. The engine 62 and the transmission 65 are controlled in accordance with the rotation speed Ne of the engine 62 detected by the control unit to drive the drive wheels 67. In addition, the motor 64 and the inverter 72 are instructed so that the motor 64 does not function as a generator or an electric motor, and the drive wheels 67 are controlled to be driven only by the engine driving force.
[0051]
In the second region 2, the control to be performed when the SOC is equal to or more than the lower limit SOC and less than the target SOC is set regardless of the required driving torque. In the second region 2, the SOC of the battery 71 is higher than the lower limit SOC, so there is no need to urgently charge the battery 71. However, since the SOC is lower than the target SOC, it is desirable to avoid lowering the SOC. Therefore, the ECU 50 controls the HEV vehicle 40 to travel by inputting only the engine driving force of the engine 62 to the driving wheels 67 without using the motor 64 as an electric motor or a generator.
[0052]
When there are control values in the third region 3 and the fourth region 4 shown in FIG. 3, the ECU 50 shown in FIG. 1 instructs the motor 64 to output the maximum torque, and sets the clutch 63 to the connected state. The engine 62 is instructed to output an insufficient torque of the required drive torque that cannot be covered by the motor maximum torque.
The third region 3 defines the control to be performed when the required driving torque is larger than the motor maximum torque and the SOC is between the target SOC and the lower limit SOC, and the fourth region 4 Defines the control to be performed when the required torque is greater than the motor maximum torque and the SOC is equal to or higher than the upper limit SOC. In the third region 3 and the fourth region 4, since the SOC of the battery 71 is equal to or higher than the target SOC, the motor 64 is actively driven to perform control for using the HEV vehicle 40 as a driving power source for traveling.
[0053]
When there are control values in the fifth region 5 and the sixth region 6 shown in FIG. 3, the ECU 50 shown in FIG. The output is controlled within the range, and the driving wheels 67 are controlled to be driven only by the motor driving force of the motor 64. At this time, the engine 62 is instructed to perform the no-load operation.
[0054]
The fifth area 5 sets the control to be performed when the required driving torque is less than the motor maximum torque and the SOC is equal to or higher than the target SOC and less than the upper limit SOC. The control to be performed when the SOC is less than the maximum torque and the SOC is equal to or more than the upper limit SOC is set. In the fifth region 5 and the sixth region 6, since the SOC of the battery 71 is higher than the target SOC, the motor 64 is actively operated, and the control is performed using the motor 64 as a driving power source for traveling the HEV vehicle 40. Perform Further, since the required driving torque can be achieved only by the motor driving force of the motor 64, there is no need to use the engine driving force of the engine 62.
[0055]
Next, the operation of the control based on the high speed range operation characteristic setting map 58b shown in FIG. 4 will be described. When there is a control value in the seventh region 7 shown in FIG. 4, the first region shown in FIG. 1 is performed. Similarly, when the control value is in the eighth area 8 shown in FIG. 4, the same control as in the second area 2 shown in FIG. 10 is performed. When the control value is in the tenth area 10 shown in FIG. 4, the same control as in the third area 3 and the fourth area 4 shown in FIG. 3 is performed, and the control value is further stored in the thirteenth area 13 shown in FIG. In the case where there is, the same control as in the above-described sixth area 6 shown in FIG. 3 is performed, so that the description thereof is omitted here.
[0056]
When the control value is in the ninth region 9 shown in FIG. 4, the ECU 50 shown in FIG. _e Is controlled to drive based on the. Further, the target engine torque T is calculated from the required drive torque. _e The motor 64 is controlled so that the insufficient torque obtained by subtracting the following is obtained from the motor 64.
[0057]
In the ninth region 9, the required driving torque is the target engine torque T _e Is set to be larger than the target SOC and less than the upper limit SOC.
Here, once again, the target engine torque T _e Will be described.
Target engine torque T _e Is a set value obtained by connecting points obtained by measuring and plotting the torque at which the amount of NOx contained in the exhaust gas from the engine 62 becomes minimum at each rotation speed by a line, as described above with reference to FIG. 2, for example. Thus, it can be shown by a dashed line in FIG. In other words, if the engine 62 is operated in accordance with the target engine torque 59, the amount of NOx contained in the exhaust gas from the engine 62 can be greatly reduced.
[0058]
Therefore, when there is a control point in the ninth region 9, the operating point of the engine 62 is fixed so as to be the target engine torque, and the required drive torque that cannot be satisfied by the target engine torque (that is, the required drive torque) Control is performed to compensate for the insufficient torque (difference between the torque and the target engine torque) by the motor driving force of the motor 64.
[0059]
When there are control values in the eleventh region 11 and the twelfth region 12 shown in FIG. 4, the ECU 50 shown in FIG. _e Is instructed to drive based on. Also, the target engine torque T _e Then, the surplus torque obtained by subtracting the required driving torque from is input to the motor 64 functioning as a generator to control the power generation.
[0060]
The eleventh region 11 sets a control to be performed when the required driving torque is smaller than the target engine torque and the SOC is equal to or more than the lower limit SOC and less than the target SOC. Control to be performed when the required torque is smaller than the target engine torque and the SOC is equal to or higher than the target SOC and lower than the upper limit SOC is set.
[0061]
In the eleventh region 11 and the twelfth region 12, the ECU 50 sets the operating point of the engine 62 to the target engine torque T described above. _e And the target engine torque T _e A control is performed in which excess torque (excess torque) generated when the required drive torque is smaller than the required drive torque is used for driving the motor 64 functioning as a generator. The surplus torque is equal to the target engine torque T _e Is obtained by subtracting the required driving torque from.
[0062]
As described above, according to the power control apparatus for a parallel hybrid electric vehicle according to one embodiment of the present invention, the engine driving force of the engine and the motor driving force of the motor are determined based on a map corresponding to the engine speed. Since the power can be selectively or combined transmitted to the drive wheels of the hybrid electric vehicle, energy loss can be suppressed and efficient driving can be achieved.
[0063]
Also, a low-revolution-range control map selected when the engine is operated at a low rotation speed (for example, when starting the vehicle) and a control map for the low-speed range selected when the engine is operated at a high rotation speed (for example, during cruising). According to the two maps, the high-speed range control map and the high-speed range control map, it is possible to efficiently transmit the driving force source corresponding to the engine speed to the driving wheels with a simple configuration.
[0064]
Further, since the engine speed at which the control map is switched is set by focusing on the NOx component amount contained in the exhaust gas from the engine, the NOx emission amount can be effectively suppressed.
In addition, since the driving characteristic setting map is set based on the driving request torque, which is a driving request from the driver, and the remaining power (SOC) in the battery, the hybrid electric power is maintained at an appropriate level while maintaining the SOC at an appropriate level. It is possible to run a car.
[0065]
In particular, by operating the engine in accordance with the target engine torque stored for each engine speed with the engine torque at which the amount of NOx component contained in the exhaust gas from the engine becomes the minimum, the NOx emission is effectively suppressed. It becomes possible. Furthermore, if the difference torque between the target engine torque and the required drive torque is positive, the difference torque is a surplus torque, and is stored in the battery as power without losing energy by using this torque for power generation. If the torque of the difference is negative, the torque is insufficient. Therefore, by assisting this with the motor driving force of the motor, the driver can effectively suppress the amount of NOx component contained in the exhaust gas from the engine. , It is possible to accurately cope with the drive request, and to suppress energy loss.
[0066]
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.
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.
[0067]
Also, the battery 71 has been described as a lithium ion battery, but may be a nickel metal hydride battery, a lead battery, or the like.
Further, in the above-described embodiment, the case where the engine 62 is a diesel engine is described, but an engine other than the diesel engine, for example, a gasoline engine or a gas turbine engine may be used.
[0068]
However, 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 due to 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 being exhausted from the engine. The reason will be described below.
[0069]
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 purifying device is installed in the exhaust pipe, and can purify the above-mentioned exhaust gas only when the fuel burns near the stoichiometric air-fuel ratio.
[0070]
Briefly explaining the purification in 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. This O oxidizes CO and HC, so that NOx is converted 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.
[0071]
In addition, if a lean NOx catalyst is used, it is possible in principle to remove NOx from exhaust gas containing too much oxygen, but a lean NOx catalyst is weak against sulfur and uses diesel fuel that uses light oil containing a large amount of sulfur as fuel. It is also difficult to use a lean NOx catalyst for the engine.
Therefore, 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 at the time when exhaust gas is released from the engine.
[0072]
Further, the diesel engine has good fuel efficiency regardless of the operating point. Therefore, by controlling the operating point (for example, torque and rotation speed) of the engine as in the present invention, exhaust gas substances (for example, NOx, HC, etc.) are controlled. The present invention is particularly useful for a parallel type HEV using a diesel engine, since it is possible to continue operation with good fuel efficiency even if the above is suppressed.
[0073]
【The invention's effect】
As described above in detail, according to the parallel hybrid electric vehicle of the present invention, the engine driving force of the engine and the motor driving force of the motor are selectively or combined based on a map corresponding to the engine speed. Since the power can be transmitted to the drive wheels of the hybrid electric vehicle, energy loss can be suppressed, and efficient travel can be achieved.
[0074]
Further, if the engine speed at which the control map is switched is set by focusing on the component amount of the predetermined substance contained in the exhaust gas contained in the exhaust gas from the engine, the component amount of the predetermined substance is effectively suppressed. (Claim 1).
Also, a low-revolution-range control map selected when the engine is operated at a low rotation speed (for example, when starting the vehicle) and a control map for the low-speed range selected when the engine is operated at a high rotation speed (for example, during cruising). By providing two maps, a high-speed range control map and a high-speed range control map, it is possible to appropriately transmit a driving force source corresponding to the engine speed to the driving wheels with a simple configuration. .
[0075]
Further, if the driving characteristic setting map is set based on the driving request torque, which is a driving request by the driver, and the remaining power (SOC) in the battery, high efficiency can be maintained while maintaining the SOC at an appropriate level. Thus, the hybrid electric vehicle can be driven (claim 3).
In addition, by operating the engine according to the target engine torque stored for each engine speed, the engine torque at which the component amount of the predetermined substance contained in the exhaust gas from the engine is minimized, the component of the predetermined substance in the exhaust gas The amount can be effectively suppressed. Further, by efficiently using or supplementing the torque (excess torque or insufficient torque) of the difference between the target engine torque and the required drive torque, it is possible to suppress the energy loss while satisfying the driver's drive requirement. (Claim 4).
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a configuration of a parallel hybrid electric vehicle according to an embodiment of the present invention.
FIG. 2 is a graph showing an engine operating state of the parallel hybrid electric vehicle according to one embodiment of the present invention.
FIG. 3 is a schematic diagram of a driving characteristic setting map for controlling a driving force source of the parallel-type hybrid electric vehicle according to one embodiment of the present invention, showing a case where the engine speed is in a low-speed rotation range. It is.
FIG. 4 is a schematic diagram of a driving characteristic setting map for controlling a driving force source of the parallel hybrid electric vehicle according to one embodiment of the present invention, showing a case where the engine speed is in a high-speed rotation range. It is.
[Explanation of symbols]
40 HEV vehicle (parallel hybrid electric vehicle)
50 Integrated control unit (power control unit; ECU)
51 memory (storage means)
57 Map Selector (Map Selector)
58 Operation characteristic setting map
58a Control map for low rotation range (operation characteristic setting map)
58b High speed range control map (operating characteristic setting map)
62 Diesel engine (engine)
64 motor (motor / generator)
67 drive wheels
69 Engine speed sensor (engine speed detecting means)
71 Battery
73 Power sensor (power remaining amount detecting means)

Claims (4)

In a power control device for a parallel hybrid electric vehicle in which both the drive shaft of the engine and the drive shaft of the motor are mechanically connected to the drive wheels of the vehicle,
Required drive torque setting means for setting a required drive torque for the drive wheel based on a driving state of the driver;
A plurality of operating characteristic setting maps for setting an operating state of the engine and the motor according to the required driving torque set by the required driving torque setting means;
Engine speed detecting means for detecting the engine speed,
When the engine speed detected by the engine speed detecting means is in a low speed range where the component amount of the predetermined material contained in the exhaust gas from the engine is relatively large, and when the predetermined material contained in the exhaust gas from the engine And a map selecting means for selecting one map from the plurality of driving characteristic setting maps in accordance with the case where the component amount is relatively high in the high rotation range.
A power control device for a parallel hybrid electric vehicle. The operating characteristic setting map is composed of a control map for a low rotation range and a control map for a high rotation range of the engine,
The map selecting means selects the low rotation speed control map when the engine rotation speed is less than the predetermined rotation speed, and selects the high rotation speed control map when the engine rotation speed is equal to or higher than the predetermined rotation speed. ,
The control map for the low rotation speed range is set so as to obtain the required drive torque for the drive wheels from the motor torque by the motor over the engine torque by the engine. A power control device for the parallel hybrid electric vehicle according to the above. A battery for supplying power to the motor;
Power remaining capacity detection means for detecting the remaining power of the battery;
The driving characteristic setting map sets a driving state of the engine and the motor in accordance with the remaining power detected by the remaining power detecting means and the required driving torque set by the required driving torque setting means. The power control device for a parallel hybrid electric vehicle according to claim 1, wherein the power control device is configured to perform the following. A storage means for storing, for each engine speed, an engine torque in which an amount of a predetermined substance contained in exhaust gas from the engine is minimum in an area not less than the predetermined number of revolutions, and holding it as a target engine torque; ,
The high rotation range control map is
Causing the engine to preferentially operate along the target engine torque,
If the required drive torque set by the required drive torque setting means is greater than the target engine torque, the motor is driven to compensate for the insufficient torque, and
If the required drive torque set by the required drive torque setting means is smaller than the target engine torque, the motor is operated as a generator and surplus torque is used for power generation. The power control device for a parallel hybrid electric vehicle according to any one of claims 2 to 3.

Images