JP2014088091A - Control device for hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid electric vehicle control device capable of selecting an efficient driving force and reducing fuel consumption deterioration with suppressing a torque shock when switching the driving source.SOLUTION: In a motor traveling area set in an area of a low engine speed and a low required torque, an engine is controlled so that only engine speed is maintained with generating a driving force of a motor (4) according to a required torque and connecting a clutch (6) without generating a driving force of the engine (2).

Description

  The present invention relates to a control device for a hybrid electric vehicle that includes an engine and an electric motor as driving sources for traveling and can switch the driving source by connecting / disconnecting a clutch, and more particularly to traveling mode selection control.

In recent years, hybrid electric vehicles including an engine and an electric motor (hereinafter referred to as a motor) as drive sources have been developed for the purpose of improving fuel consumption and exhaust gas performance.
For example, there is a hybrid electric vehicle in which a clutch is provided between an engine and a motor, and a drive source can be switched by connecting and disconnecting the clutch. In such a hybrid electric vehicle, it is possible to run with only the motor by stopping the engine and disengaging the clutch. In addition, when the required driving torque cannot be achieved only by the motor or engine driving torque, the driving torque combining the engine and the motor can be used by connecting the clutch.

Therefore, in the hybrid electric vehicle, efficient driving is realized by switching according to the situation, traveling using only the motor, traveling using only the engine, and traveling using both the motor and the engine.
For example, a motor assist amount is determined according to the driving state of the vehicle during vehicle acceleration, and the determined assist amount is corrected according to a charge amount (also referred to as SOC: State Of Charge) of the power storage device (battery) at that time. Hybrid electric vehicles have been developed (see Patent Document 1).

  Also, a hybrid electric vehicle has been developed that calculates a required torque from the accelerator opening and compares the engine efficiency and the motor efficiency as a drive source for outputting the required torque, and selects the more efficient drive source ( Patent Document 2).

JP 2000-69609 A JP 2002-118903 A

However, when the assist amount of the motor is set based on the SOC of the battery as in Patent Document 1, if the SOC is sufficient and the assist amount of the motor is increased and the torque distribution of the engine is reduced, the engine is not operated efficiently. May be done.
In the above Patent Document 2, a gasoline engine is assumed as an engine. However, in the case of a diesel engine that is basically more efficient than a gasoline engine, an efficient operating region is different from that of a gasoline engine. It is difficult to apply this technology directly to a diesel-electric hybrid electric vehicle.

  Also, in a hybrid electric vehicle in which switching between the engine and the motor is performed by connecting / disconnecting the clutch, a state in which the clutch is disconnected and the vehicle is driven only by the motor is switched to traveling using the engine by connecting the clutch. In order to suppress torque shock, it is necessary to match the rotation of the engine side and the motor side. At this time, a relatively large amount of fuel is consumed in order to increase the rotational speed of the engine that has been stopped or idling. For this reason, there is also a problem that fuel consumption deteriorates when the drive source is frequently switched.

  The present invention has been made to solve such a problem, and the object of the present invention is to select an efficient drive source and to reduce fuel consumption deterioration while suppressing torque shock at the time of drive source switching. An object of the present invention is to provide a control apparatus for a hybrid electric vehicle that can be used.

  In order to achieve the above-described object, the hybrid electric vehicle control device according to claim 1 is a hybrid electric vehicle control device including an engine and an electric motor as drive sources, and is provided between the engine and the electric motor. A clutch that connects and disconnects the driving force of the engine transmitted from the engine to the drive wheels via the electric motor, and when the electric motor is used as a driving source, the clutch is in a connected state, Engine control means for controlling the engine so as to maintain only the engine rotation without generating a driving force by the engine.

  According to a hybrid electric vehicle control device of a second aspect, in the first aspect, the required torque calculation means for calculating the required torque based on the accelerator opening, the engine speed detection means for detecting the engine speed of the engine, Travel mode selection control means for selecting either one or both of the engine and the electric motor as a drive source based on a map that defines the travel mode according to the required torque and the engine speed, and the travel mode selection control means In the map, at least in a predetermined operating range determined from the efficiency of the engine, the required torque, and the frequency of use of the engine speed, the engine control means controls the clutch while using the electric motor as a drive source. Connected to the engine without generating driving force from the engine. It is set to drive mode for controlling the engine so as to maintain the rotational only are characterized.

  The hybrid electric vehicle control device according to claim 3, wherein the map in the travel mode selection control means is the predetermined driving region within a range of operating states in which the efficiency of the engine is low and the frequency of use is high. Is set.

  According to the hybrid electric vehicle control apparatus of the first aspect of the present invention using the above-described means, when traveling using the electric motor as a drive source, the clutch is brought into a connected state, and only the engine rotation is performed without generating the driving force by the engine. It will be maintained. That is, the load on the electric motor is not increased by supplying only a small amount of fuel that can maintain the rotation of the engine while the engine is rotated synchronously with the electric motor by setting the clutch in a connected state.

  As a result, it is not necessary to match the rotational speed of the clutch when traveling from traveling using an electric motor as a drive source to traveling using an engine, and the traveling mode can be smoothly transitioned, and extra for adjusting the rotational speed. No more fuel is consumed. Since the clutch remains connected, there is no torque shock or the like, and the driver does not feel uncomfortable. Therefore, fuel consumption deterioration can be reduced while suppressing torque shock at the time of switching the drive source.

  According to the hybrid electric vehicle control apparatus of the second aspect, the drive source is selected based on the map in which the travel mode is determined according to the required torque and the engine speed. This map shows that within a predetermined operating range determined from engine efficiency, required torque, and frequency of use of engine speed, the clutch is engaged while the motor is the driving source and the driving force by the engine is generated. It is set to select a travel mode that maintains only the engine speed without any change.

Thus, the electric motor can be used according to the engine efficiency and the use frequency by determining the range using the electric motor as the drive source from the engine efficiency and the use frequency of the operating state. Thereby, an efficient drive source can be selected.
According to the control apparatus for a hybrid electric vehicle of the third aspect, in the map for determining the driving mode, the clutch is engaged while the electric motor is used as the driving source, and only the engine rotation is maintained without generating the driving force by the engine. The operating range is determined in a range where the engine efficiency is low and the required torque and engine speed are frequently used.

  In other words, the engine is not used as a drive source in the operation region where the engine efficiency is low and frequently used, and the operation by the electric motor is actively performed. The effect of maintaining the engine rotation with the clutch connected is particularly effective in driving conditions in which the driving mode is frequently switched. Become. As a result, traveling with poor engine efficiency can be avoided, and an efficient drive source with improved fuel efficiency can be selected.

It is a schematic block diagram of the control apparatus of the hybrid electric vehicle in one Embodiment of this invention. It is an example of the driving mode selection map memorize | stored in ECU of the control apparatus of the hybrid electric vehicle in one Embodiment of this invention. It is explanatory drawing which sets the drive source switching line in FIG. It is explanatory drawing which shows the drive source switching line for every gear stage. It is a flowchart which shows the clutch control routine at the time of deceleration which ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a control apparatus for a hybrid electric vehicle according to an embodiment of the present invention, which will be described with reference to FIG.
A vehicle 1 shown in FIG. 1 is a truck of a hybrid electric vehicle including an engine 2 and a motor 4 (electric motor) as drive sources.

  The engine 2 is a diesel engine, and the diesel engine is provided with an exhaust treatment device such as a DPF (Diesel particulate filter) not shown. A clutch 6 is provided between the engine 2 and the motor 4. The output shaft of the engine 2 is connected to the input shaft (input side) of the clutch 6, and the rotation shaft of the motor 4 is connected to the output shaft (output side) of the clutch 6.

  The motor 4 is, for example, a permanent magnet type synchronous motor that can generate power, and the rotating shaft of the motor 4 is connected to the input shaft of the transmission 8. The transmission 8 includes a plurality of gears, shifts the driving force input through the gears corresponding to the selected shift speed, and transmits them to the output shaft of the transmission 8. The drive force is transmitted from the output shaft of the transmission 8 to the left and right drive wheels 16 via the propeller shaft 10, the differential device 12, and the drive shaft 14.

  The motor 4 is connected to a battery 18 mounted on the vehicle 1 via an inverter 20, and receives torque from the battery 18 to generate torque. The battery 18 is a secondary battery such as lithium ion or nickel metal hydride, and the inverter 20 converts the DC power from the battery 18 into AC power and supplies the motor 4 with power. On the other hand, when the vehicle is decelerated, the motor 4 functions as a generator and is regeneratively driven. That is, the motor 4 generates AC power by the driving force transmitted in reverse from the driving wheels 16, and the regenerative torque generated by the motor 4 at this time acts as a braking torque for the driving wheels 16 and functions as a so-called regenerative brake. . The AC power is converted into DC power by the inverter 20 and then charged to the battery 18 so that the kinetic energy due to the rotation of the drive wheels 16 is recovered as electric energy.

  In the vehicle 1 having such a configuration, only the rotating shaft of the motor 4 is mechanically connected to the drive wheels 16 via the transmission 8 when the clutch 6 is in the disconnected state. That is, only the torque generated by the motor 4 (hereinafter referred to as motor torque) is transmitted to the drive wheels 16 as the drive torque or braking torque of the vehicle 1. Such traveling using only the motor 4 as a driving source is hereinafter referred to as motor traveling.

  On the other hand, when the clutch 6 is in the connected state, the output shaft of the engine 2 is mechanically connected to the transmission 8, the drive wheels 16 and the like via the rotating shaft of the motor 4. That is, at this time, when the motor torque is set to 0 and only the engine 2 is operated, only the torque generated by the engine 2 (hereinafter referred to as engine torque) becomes the driving torque or braking torque of the vehicle 1. Such traveling using only the engine 2 as a driving source is hereinafter referred to as engine traveling.

If the motor 4 is also operated in this state, the sum of the motor torque and the engine torque becomes the driving torque or braking torque of the vehicle 1. Such traveling using both the engine 2 and the motor 4 as a drive source is hereinafter referred to as hybrid traveling.
The vehicle 1 is equipped with an ECU (Electronic Control Unit) 22 that integrally controls the engine 2, the motor 4, the clutch 6, and the transmission 8 in order to adjust the distribution of the motor torque and the engine torque. Has been.

The ECU 22 is communicably connected to a control unit (not shown) of each engine 2, motor 4, clutch 6, and transmission 8 using a CAN (Controller Area Network) or the like.
For example, the ECU 22 is currently selected from the information such as the fuel injection amount and the injection timing from the engine 2, the information from the clutch 6 to the connection state of the clutch 6, the motor rotation number information and the motor torque information from the motor 4, and the transmission 8. Various information such as the current gear position information and SOC information from the battery 18 is acquired.

  Further, the vehicle 1 is provided with sensors such as an engine speed sensor 24 (engine speed detection means) for detecting the speed of the engine 2 and an accelerator sensor 26 for detecting the accelerator opening corresponding to depression of the accelerator pedal. It has been. The ECU 22 is connected to each of the sensors 24 and 26 so as to be able to transmit information.

The ECU 22 configured as described above monitors the SOC of the battery 18 and the driving state of the vehicle 1, and optimizes fuel consumption and exhaust gas performance, and performs engine 2 and motor 4 to perform driving according to the driver's request. The clutch 6, the transmission 8, etc. are controlled.
For example, the ECU 22 calculates the driver's required torque from the accelerator opening detected by the accelerator sensor 26 (requested torque calculating means). In the ECU 22, a travel mode selection map for selecting each travel mode of motor travel, engine travel, and hybrid travel according to the required torque and the engine speed is stored for each gear position of the transmission 8. The ECU 22 selects a travel mode based on the map and various other driving states (travel mode selection control means).

  2 to 4, FIG. 2 shows an example of the travel mode selection map, FIG. 3 shows an explanatory diagram of the drive source switching line setting in FIG. 2, and FIG. 4 shows the drive for each shift stage. An explanatory view showing a source switching line is shown. Note that the horizontal axis of the maps shown in these figures represents the engine speed, and the vertical axis represents the required torque. The driving mode selection maps shown in FIGS. 2 and 3 are for the case where the transmission 8 is in the third speed.

As shown in FIG. 2, in the travel mode selection map, a motor travel region in which the motor travel mode is set is set in the region of the low engine speed and the low required torque. An engine traveling region for setting the engine traveling mode is set in the region of the high required torque.
In the map, a line indicating the maximum torque that can be output by the engine 2 (hereinafter referred to as engine maximum torque) is shown as a convex shape in the range of the high required torque. For the region where the engine speed is low and the required torque is higher than the engine maximum torque line, a hybrid travel region is set to a hybrid travel mode in which the motor torque compensates for the insufficient torque only by the engine torque. .

  In the motor travel region, the ECU 22 controls the engine 2 so as to generate only the driving force of the motor 4 according to the required torque, and keep only the engine rotation without generating the driving force by the engine 2 with the clutch 6 in the connected state ( Engine control means). That is, the ECU 22 supplies the small amount of fuel that can maintain the rotation of the engine 2 while rotating the engine 2 synchronously with the clutch 6 in the connected state so that the load on the motor 4 does not increase. To. The ECU 22 gradually increases the engine torque while gradually decreasing the motor torque while the clutch 6 is connected when the required torque and the engine speed shift to the engine travel region in the travel mode selection map. Specifically, the engine running mode is shifted to cover all the required torque with the engine torque.

  In the travel mode selection map of FIG. 2, the drive source is switched at the boundary line between the motor travel region and the engine travel region, and this line (hereinafter referred to as drive source switching line) is the fuel consumed in the engine 2. Energy efficiency (hereinafter referred to as engine efficiency), engine speed and required torque frequency used in normal vehicle travel (hereinafter referred to as usage frequency), and maximum torque that can be output by the motor 4 Is set based on a line (hereinafter referred to as a motor maximum torque line).

Specifically, as shown in FIG. 3, the drive source switching line has a shape that expands toward the low engine efficiency side as the engine speed increases in the same manner as the motor maximum torque line shape, and partially overlaps the high usage frequency region. It is like that.
Furthermore, as shown in FIG. 4, the drive source switching line has a lower required engine torque side with a lower engine efficiency and a higher engine speed side as the gear stage increases to the third speed, fourth speed, fifth speed, and sixth speed. It becomes an extended shape. Although not shown, the drive switching line is also set for each SOC of the battery 18, and the motor travel region tends to decrease as the SOC decreases.

The ECU 22 selects a travel mode based on the travel mode selection map set in this way and other various operation states.
Referring now to FIG. 5, there is shown a flowchart showing a travel mode selection control routine, which will be described below along the same flowchart. The travel mode selection control routine is executed when the accelerator pedal is in the travel state.
First, as step S1 in FIG. 5, the ECU 22 determines whether the SOC of the battery 18 is greater than or equal to a first predetermined value or when the vehicle is starting. The first predetermined value is set to, for example, an upper limit value (for example, 60%) of the SOC range in which the battery 18 can be normally used. If the determination result is true (Yes), the process proceeds to step S2.

  In step S2, the ECU 22 controls the motor 4 and the like so that the motor travels with the clutch 6 in the disengaged state, and the routine returns. This is because the engine 2 is not scheduled to be used for a long time when the SOC of the battery 18 that satisfies the condition of step S1 is sufficient, and the engine is stopped when the vehicle is started. The fuel consumption can be improved by disengaging the clutch 6 and stopping the engine 2 rather than consuming a small amount of fuel to maintain the rotation. Therefore, the ECU 22 selects the motor travel mode with the clutch 6 disengaged regardless of the travel mode selection map shown in FIG.

On the other hand, if the determination result in step S1 is false (No), that is, if the SOC is not more than the first predetermined value and the vehicle is not starting, the process proceeds to step S3.
In step S3, the ECU 22 determines whether or not the requested torque is greater than the engine maximum torque. If the determination result is true (Yes), that is, if the required torque is in the hybrid travel region on the travel mode selection map of FIG. 2, the process proceeds to step S4.

In step S4, the ECU 22 controls the engine 2 and the motor 4 so as to perform the hybrid running in which the torque that is insufficient by the engine torque is compensated by the motor torque, and returns the routine.
On the other hand, if the determination result in step S3 is false (No), that is, if the required torque is equal to or less than the engine maximum torque, the process proceeds to step S5.

  In step S5, the ECU 22 determines whether or not the SOC of the battery 18 is greater than a second predetermined value. The second predetermined value is set to a lower limit value (for example, 35%) of the SOC range in which the battery 18 can be normally used. When the determination result is true (Yes), that is, when the motor 4 can be used, the process proceeds to the next step S6.

In step S6, the ECU 22 determines whether or not the gear stage of the transmission 8 is greater than a predetermined stage. For example, the predetermined gear is set to a gear (for example, the third speed) selected when the vehicle 1 starts. If the determination result is true (Yes), the process proceeds to the next step S7.
In step S7, the ECU 22 determines whether or not the required torque and the engine speed are within the range surrounded by the drive source switching line (in the motor travel region) in the travel mode selection map shown in FIG. If the determination result is true (Yes), the process proceeds to the next step S8.

  In step S8, the ECU 22 determines whether or not the required torque is smaller than the motor maximum torque limit value. The motor maximum torque limit value is a value that limits the motor maximum torque, and is set according to the temperature of the motor 4, the SOC, and the like. When the determination result is true (Yes), that is, when the required torque can be generated only by the motor 4, the process proceeds to the next step S9.

In step S9, the ECU 22 determines whether or not the DPF provided in the engine 2 is not being regenerated. If the determination result is true (Yes), that is, if all the conditions of steps S5 to S9 are satisfied, the process proceeds to step S10.
In step S10, the ECU 22 selects motor travel with the clutch 6 in a connected state, and returns the routine. As described above, at this time, the ECU 22 controls the engine 2 so as to maintain only the engine rotation without generating a driving force.

  On the other hand, if any of the determination results in steps S5 to S9 is false (No), the process proceeds to step S11. For example, when the SOC of the battery 18 is less than or equal to the second predetermined value and it becomes difficult to use the motor 4, when the gear stage is smaller than the predetermined stage and the torque fluctuation is large, the required torque and the engine speed are switched to the drive source. If the engine efficiency is outside the range of the line and the engine efficiency is not low, the required torque is equal to or greater than the motor maximum torque limit value and the motor 4 alone cannot satisfy the required torque, or the engine 2 needs to be operated during DPF regeneration. If yes, go to Step S11.

In step S11, the ECU 22 controls the engine 2 to run the engine alone with the clutch 6 in the connected state, and returns the routine.
As described above, the ECU 22 keeps only the engine rotation without generating the driving force by the engine 2 when the travel using the motor 4 as the drive source is performed in step S10 and the clutch 6 is connected. As a result, when shifting to travel using the engine 2 as a drive source in step S4 or step S11, it is not necessary to adjust the engine speed to connect the clutch 6, and the travel mode can be transitioned smoothly. In addition, unnecessary fuel for adjusting the rotational speed is not consumed. Since the clutch 6 remains connected, there is no torque shock or the like and the driver does not feel uncomfortable.

The motor travel in step S10 is selected mainly based on the travel mode selection map, and the area in which the motor travel is performed is set according to the efficiency and use frequency of the engine 2 and the maximum motor torque. Thus, efficient drive source selection can be realized.
Specifically, in the operation region where the engine efficiency is low and frequently used, the engine 2 is not used as a drive source, and the operation by the motor 4 is actively performed. The effect of maintaining the engine rotation with the clutch 6 connected at this time is particularly effective under the driving conditions in which the driving mode is frequently switched. To make it more efficient.

Therefore, in the control apparatus for a hybrid electric vehicle according to the present embodiment, it is possible to avoid driving with poor engine efficiency, and to select an efficient driving source with improved fuel efficiency, and at the time of switching the driving source. It is possible to reduce fuel consumption deterioration while suppressing torque shock.
Although the description of the embodiment of the control apparatus for a hybrid electric vehicle according to the present invention is finished above, the embodiment is not limited to the above embodiment.

For example, in the above embodiment, the vehicle 1 is a truck, but the present invention can also be applied to a passenger car of a hybrid electric vehicle equipped with a diesel engine.
Moreover, the maps shown in FIGS. 2 to 4 of the above embodiment show an example of the tendency of the drive source switching line and the like, and change according to the use of each vehicle. For example, the drive source switching line does not need to have the same shape as that of the motor maximum torque, and may be set based on at least the engine efficiency and the use frequency. Further, as shown in FIG. 4, the drive source switching line may be fixed without being changed in accordance with the gear position.

1 Vehicle 2 Engine 4 Motor (electric motor)
6 Clutch 8 Transmission 18 Battery 22 ECU (Engine control means, required torque calculation means, travel mode selection control means)
24 engine speed sensor (engine speed detection means)
26 Accelerator sensor

Claims (3)

A control device for a hybrid electric vehicle having an engine and an electric motor as drive sources,
A clutch provided between the engine and the electric motor for connecting and disconnecting the driving force of the engine transmitted from the engine to the driving wheels via the electric motor;
An engine control means for controlling the engine so as to maintain only the engine rotation without generating the driving force by the engine when the electric motor is driven as a drive source;
A control apparatus for a hybrid electric vehicle, comprising: A required torque calculating means for calculating a required torque based on the accelerator opening;
Engine speed detecting means for detecting the engine speed of the engine;
Travel mode selection control means for selecting one or both of the engine and the electric motor as a drive source based on a map that defines a travel mode according to the required torque and the engine speed,
The map in the travel mode selection control means is the engine while using the electric motor as a drive source at least within a predetermined operation region determined from the efficiency of the engine, the required torque, and the use frequency of the engine speed. 2. The hybrid according to claim 1, wherein the driving mode is set to control the engine so that the clutch is engaged by the control means and only the engine rotation is maintained without generating the driving force by the engine. Electric vehicle control device.   3. The hybrid electric vehicle according to claim 2, wherein the predetermined operating range is set in the range of the operating state in which the efficiency of the engine is low and the frequency of use is high in the map in the driving mode selection control unit. Automotive control device.

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