JP5795854B2 - Control device for hybrid electric vehicle - Google Patents

Description

  The present invention relates to a hybrid electric vehicle that travels with power output from at least one of an internal combustion engine and an electric motor that uses power stored in a battery as a power source, and that generates a regenerative braking torque during regeneration of the electric motor and decelerates. The present invention relates to the technical field of control devices.

  In recent years, attention has been focused on an internal combustion engine such as a gasoline engine or a diesel engine, and a hybrid electric vehicle that can run using at least one of an electric motor that can be driven by electric power stored in a battery as a power source. In this type of hybrid electric vehicle, the motor is regeneratively driven during deceleration to store the kinetic energy of the vehicle in the battery as electric energy (electric power), and the motor is powered by the stored electric power to drive the fuel consumption of the internal combustion engine. To improve fuel efficiency.

  In order to further improve fuel efficiency in hybrid electric vehicles, it is important how to efficiently recover regenerative energy during deceleration. In particular, since regenerative braking torque is generated according to the regenerative energy to be recovered in the electric motor, the regenerative energy recovery efficiency should be maximized while considering that the generated regenerative braking torque is in a range that does not give the driver a sense of incongruity. Is an issue. For example, in Patent Document 1, the regenerative braking torque generated by the electric motor at the time of deceleration is variably set according to the depression amount and the depression speed of the brake pedal, thereby realizing the deceleration behavior in accordance with the intention of the driver. A technique for improving the recovery efficiency of regenerative energy is described.

JP-A-6-253406

  According to Patent Document 1, the regenerative braking torque generated by the electric motor at the time of deceleration is set to have a proportional relationship with the depression amount and the depression speed of the brake pedal, and the proportionality coefficient is fixed regardless of the driving condition. Has been. In the first place, the behavior of the vehicle intended by the driver when decelerating varies depending on the driving conditions in which the vehicle is placed. Nevertheless, in Patent Document 1, the regenerative braking torque is uniformly calculated based only on the depression amount and the depression speed of the brake pedal regardless of the traveling condition of the vehicle. Therefore, depending on the running conditions of the vehicle, there is a problem that the regenerative braking torque becomes a value far from the driver's intention, and in some cases a shock or the like deteriorates drivability.

  Specifically, in Patent Document 1, when the proportionality coefficient is set to a large value, the magnitude of the regenerative braking torque becomes excessive, giving the driver a shock, and drivability deteriorates. Concerned. Therefore, in Patent Document 1, it is necessary to set the proportionality coefficient small in order to prevent such deterioration of drivability. As a result, there is a problem that the regenerative energy recovery efficiency also decreases as the regenerative braking torque generated during regeneration decreases.

  The present invention has been made in view of the above problems, and an object thereof is to provide a control device for a hybrid electric vehicle that can efficiently recover regenerative energy without deteriorating drivability during regenerative braking of an electric motor. To do.

In order to solve the above-described problems, a control apparatus for a hybrid electric vehicle according to the present invention transmits power output from at least one of an internal combustion engine and an electric motor powered by using electric power stored in a battery via a transmission. A control device for a hybrid electric vehicle that travels by transmitting to a driving wheel and transmits the regenerative braking torque to the driving wheel and decelerates by driving the motor regeneratively, and detects a depression amount of a brake pedal A pedal depression amount detecting means; a rotational speed detecting means for detecting the rotational speed of the electric motor;
A reference regenerative braking torque of the electric motor is calculated based on the detected gear speed and the detected gear speed based on the detected gear speed and the detected gear speed. When the sum of the regenerative braking torque and the additional regenerative braking torque is less than the maximum regenerative braking torque of the motor, the additional regeneration calculated based on the detected depression amount of the brake pedal, the rotation speed of the motor, and the gear position. Regenerative braking torque calculating means for calculating the regenerative braking torque by adding a braking torque to the reference regenerative braking torque, wherein the regenerative braking torque is obtained by changing the rotation speed of the motor from the first rotation speed to the first rotation speed. It is set to increase over a second rotational speed higher than the rotational speed, and to decrease from the second rotational speed to a third rotational speed higher than the second rotational speed, and , Characterized in that it is set to zero in the first rotational speed is less than range.

  According to the present invention, when the reference regenerative braking torque is less than the maximum regenerative braking torque of the motor, the regenerative energy recovery efficiency is set by adding the regenerative braking torque and adding the regenerative braking torque to the reference regenerative braking torque. Can be improved. In particular, the additional regenerative braking torque is calculated according to the vehicle running conditions (the amount of depression of the brake pedal, the number of revolutions of the electric motor, and the gear position of the transmission), so that reference regenerative braking is performed to prevent deterioration of drivability. Even when the torque is set to be relatively small, good regenerative energy recovery efficiency can be obtained.

Preferably, the plus regenerative braking torque may shift speed of the transmission is set so as to decrease in accordance with decrease. In this case, since the additional regenerative braking torque is set to be smaller as the gear ratio of the shift speed becomes smaller (that is, when the gear is on the low speed side), the vehicle safety on the low speed side can be ensured satisfactorily. In other words, when the vehicle is in a driving condition such as when the vehicle is required to be accurately controlled by the driver's depression of the brake pedal, the regenerative braking torque is suppressed by setting the additional regenerative braking torque to a small value. Safety can be improved by enabling the vehicle to be controlled more faithfully by operating the brake pedal.

  The additional regenerative braking torque may be set so as to increase as the amount of depression of the brake pedal increases. In this case, since it is assumed that the driver intends a rapid deceleration as the amount of depression of the brake pedal increases, the recovery efficiency of regenerative energy can be improved by increasing the additional regenerative braking torque.

  When the reference regenerative braking torque is greater than the maximum regenerative braking torque, the regenerative braking torque is set to the maximum regenerative braking torque, and is provided between the output shaft of the internal combustion engine and the input shaft of the electric motor. A clutch may be connected to decelerate by applying an engine brake by the internal combustion engine. In this case, if the reference regenerative braking torque exceeds the maximum regenerative braking torque of the motor, the regenerative drive of the motor is regenerated and the regenerative braking torque of the motor covers as much as possible. The braking force that cannot be overcome can be supplemented by engine braking.

  According to the present invention, when the reference regenerative braking torque is less than the maximum regenerative braking torque of the motor, the regenerative energy recovery efficiency is set by adding the regenerative braking torque and adding the regenerative braking torque to the reference regenerative braking torque. Can be improved. In particular, the additional regenerative braking torque is calculated according to the vehicle running conditions (the amount of depression of the brake pedal, the number of revolutions of the electric motor, and the gear position of the transmission), so that reference regenerative braking is performed to prevent deterioration of drivability. Even when the torque is set to be relatively small, good regenerative energy recovery efficiency can be obtained.

1 is a block diagram conceptually showing an overall configuration of a hybrid electric vehicle according to the present invention. It is a flowchart figure which shows the control content of the hybrid electric vehicle which concerns on this invention. It is a graph which shows the relationship between a motor rotation speed and a reference | standard regenerative braking torque. It is a graph which shows the relationship between the depression amount of a brake pedal, motor rotation speed, a gear stage, and an addition regenerative braking torque.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a block diagram conceptually showing the overall configuration of a hybrid electric vehicle 1 according to the present invention. A hybrid electric vehicle 1 according to the present invention is a parallel hybrid electric vehicle, and an input shaft of a clutch 3 is connected to an output shaft of a diesel engine 2 (hereinafter referred to as “engine 2”). Further, the input shaft of the transmission 5 is connected to the motor 4 through the rotation shaft. Left and right drive wheels 9 are connected to the output shaft of the transmission 5 via a propeller shaft 6, a differential 7 and a drive shaft 8. Each of the left and right drive wheels 9 is provided with a brake 12 so that the driver can decelerate the vehicle by generating a mechanical braking torque when the driver depresses the brake pedal 13. .

  The engine 2 is an internal combustion engine that functions as one of the power sources of the hybrid electric vehicle 1. The engine 2 is a diesel engine. For example, by reciprocating the air at high temperature and injecting fuel in the combustion chamber, the reciprocating motion of the piston caused by the explosive force by combustion using spontaneous ignition can be converted into the rotational motion of the output shaft. It is configured to be possible.

  The clutch 3 is provided between the output shaft of the engine 2 and the rotating shaft of the motor 4, and is a power transmission mechanism configured to be able to switch these mechanical connection states. When the clutch 3 is connected, since the output shaft of the engine 2 is mechanically connected to the rotation shaft of the motor 4, the drive wheel 9 is connected to both the output shaft of the engine 2 and the rotation shaft of the motor 4. It will be. On the other hand, when the clutch 3 is disengaged, the output shaft of the engine 2 is mechanically disconnected from the rotating shaft of the motor 4, so that only the rotating shaft of the motor 4 is connected to the drive wheel 9 via the transmission 5. Will be connected.

  The motor 4 functions as one of the power sources of the hybrid electric vehicle 1 by converting the DC power stored in the battery 11 to AC by the inverter 10 and driving it, and AC generated by the motor 4 during regeneration. It is an electric motor that functions as a generator that converts electric power into direct current by the inverter 10 and charges the battery 11.

  The transmission 5 is a power transmission mechanism configured to be able to switch between a plurality of gear stages having different gear ratios, and the power output from the engine 2 and the motor 4 is transmitted via the propeller shaft 6, the differential device 7, and the drive shaft 8. To the left and right drive wheels 9. Particularly in the present embodiment, the transmission 5 is a five-speed forward / reverse one-stage transmission, and the “first speed” side, which is the low speed side of the forward speed, has a small gear ratio, and the “5-speed” side, which is the high speed side, changes the speed. The ratio is set to be large. The transmission 5 may be an automatic transmission or a manual transmission. In addition, although the speed change stage of the transmission 5 is five forward speeds and one reverse speed, it need not be limited to this.

  The battery 11 is a storage battery capable of storing DC power for powering the motor 4. Direct current power is stored in the battery 11, and the direct current power is AC converted by the inverter 10 and then supplied to the motor 4. On the other hand, charging of the battery 11 is performed by supplying AC power generated by regeneration of the motor 4 to the battery 11 after being DC converted (rectified) by the inverter 10.

  When the clutch 3 is in the connected state, the output shaft of the engine 2 is mechanically connected to the rotating shaft of the motor 4, so that the drive wheel 9 is connected to both the output shaft of the engine 2 and the rotating shaft of the motor 4. . In this case, when the motor 4 is powered, both the output torque of the engine 2 and the output torque of the motor 4 are transmitted to the drive wheels 9 via the transmission 5. That is, a part of the drive torque of the drive wheels 9 is supplied from the engine 2 and the rest is supplied from the motor 4. Further, when the charge amount of the battery 11 decreases during traveling, the motor 4 is regeneratively driven with the remainder of the output torque of the engine 2 while driving the drive wheels 9 using a part of the output torque of the engine 2. By doing so, the battery 11 can also be charged.

  When the clutch 3 is disconnected (that is, not in the connected state), the output shaft of the engine 2 is mechanically disconnected from the rotating shaft of the motor 4 and only the rotating shaft of the motor 4 is connected to the drive wheels 9. It is mechanically connected via the transmission 5. In this case, when the motor 4 is powered, the output torque of the engine 2 is not transmitted to the drive wheels 9 and only the output torque of the motor 4 is transmitted. That is, the hybrid electric vehicle 1 travels exclusively by driving the motor 4 using the electric power stored in the battery 11.

  The brake pedal 13 transmits a mechanical braking torque to the drive wheels 9 to decelerate the vehicle by operating the brakes 12 provided on the drive wheels 9 in accordance with the depression amount by the driver. Further, the accelerator pedal 14 increases the output torque of at least one of the engine 2 and the motor 4 that are power sources according to the amount of depression by the driver to accelerate the vehicle. In this embodiment, a hydraulic brake pedal 13 and an accelerator pedal 14 are employed.

  The vehicle ECU 26 is an electronic control unit configured to be able to control the entire operation of the hybrid electric vehicle 1 together with the engine ECU 27, the inverter ECU 28, and the battery ECU 29. Thus, the vehicle ECU 26 is configured to control the operation state of each part of the hybrid electric vehicle 1 including the engine 2, the clutch 3, the motor 4, and the transmission 5, and to obtain the control state of each part. Has been.

  For example, the vehicle ECU 26 detects the depression amount of the brake pedal 13 by detecting the depression amount of the brake pedal 13 as an electrical signal by a hydraulic sensor (not shown) installed in the hydraulic path of the brake pedal 13. Further, the vehicle ECU 26 detects the depression amount of the accelerator pedal 14 by detecting the depression amount of the accelerator pedal 14 as an electric signal by an accelerator opening sensor (not shown). Further, the vehicle ECU 26 can detect which gear stage is selected in the transmission 5 by accessing the transmission 5, and can detect the motor rotation speed by accessing the motor 4. It is configured. That is, the vehicle ECU 26 functions as an example of the “brake pedal depression amount detecting means”, “rotational speed detecting means”, and “shift speed detecting means” of the present invention.

  The engine ECU 27 is an electronic control unit for performing various controls necessary for the operation of the engine 2. For example, fuel injection in the engine 2 is performed so that torque to be output from the engine 2 set by the vehicle ECU 26 can be output. Control the amount and injection timing.

  The inverter ECU 28 is an electronic control unit for performing various controls necessary for the operation of the inverter 10. For example, the inverter ECU 28 controls the inverter 10 so that torque to be output from the motor 4 set by the vehicle ECU 26 can be output. Thus, the motor 4 is controlled to be powered or regeneratively operated.

  The battery ECU 29 obtains the amount of charge of the battery 11 by obtaining information obtained from a battery current sensor or a battery voltage sensor (not shown) capable of detecting the current and voltage of the battery 11 via the vehicle ECU 26, The obtained SOC is transmitted to the vehicle ECU 26.

  The vehicle ECU 26, the engine ECU 27, the inverter ECU 28, and the battery ECU 29 described above are electronic control units each including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In accordance with the control program stored in the program, various controls described later can be executed. The physical, mechanical and electrical configurations of these various controls are not limited to this.

  Next, a specific operation of the hybrid electric vehicle 1 configured as described above will be described with reference to FIG. FIG. 2 is a flowchart showing the control contents of the hybrid electric vehicle 1 according to the present invention.

  First, the vehicle ECU 26 determines whether or not the accelerator pedal 14 is OFF by detecting the depression amount from the accelerator pedal 14 (step S101). When the accelerator pedal 14 is ON (step S101: NO), it is assumed that the driver does not intend to decelerate the vehicle. Therefore, it is not necessary to perform the control described below, and the vehicle ECU 26 ends the process (END). . On the other hand, when the accelerator pedal 14 is OFF (step S101: YES), the vehicle ECU 26 further detects the depression amount from the brake pedal 13 to determine whether or not the brake pedal 13 is ON (step S102). .

  When the brake pedal 13 is ON (step S102: YES), the vehicle ECU 26 acquires the depression amount F, the motor rotation speed R, and the gear stage S of the brake pedal 13 (step S103), and the obtained depression amount of the brake pedal. A reference regenerative braking torque Tsr and an additional regenerative braking torque Tad are calculated based on F, the motor rotation speed R, and the gear stage S (step S104 & step S105).

  In step S104, the reference regenerative braking torque Tsr is calculated based on the motor rotation speed R and the gear stage S acquired in step S103. Here, FIG. 3 is a graph showing the relationship between the motor speed R and the reference regenerative braking torque Tsr. The reference regenerative braking torque Tsr increases with an increase in the motor rotational speed R in the range where the motor rotational speed is equal to or greater than R0, and reaches the maximum regenerative braking torque Tm of the motor 4 (see the alternate long and short dash line). Set to follow. Such a correspondence relationship between the motor rotational speed R and the reference regenerative braking torque Tsr is set in advance by a theoretical, experimental, or simulation method for each gear position, and stored in advance in a memory or the like built in the vehicle ECU 26. Has been.

  In step S105, an additional regenerative braking torque Tad is calculated based on the brake pedal depression amount F, the motor rotation speed R, and the gear stage S acquired in step S103. FIG. 4 is a graph showing the relationship between the brake pedal depression amount F, the motor rotation speed R, the shift speed S, and the additional regenerative braking torque Tad.

  FIG. 4A shows the relationship between the additional regenerative braking torque Tad and the motor rotational speed R when the gear stage S of the transmission 5 is set to “fifth speed”. The additional regenerative braking torque Tad is set so that the motor rotation speed increases from R0 or more toward R1, and decreases as it goes from R1 or more to R2. Further, the additional regenerative braking torque Tad is set to increase as the amount of depression of the brake pedal increases. This is because when the amount of brake pedal depression is large, the driver intends to suddenly decelerate, so it is in line with the driver's intention to set a large regenerative braking torque, and the recovery efficiency of regenerative energy is improved. This is because it can be improved.

  On the other hand, the additional regenerative braking torque Tad is set to zero in a range where the motor speed is smaller than R0 (for example, a region close to a creep region or a stopped state). This is because the vehicle speed is assumed to be low (close to a stopped state) in a region where the motor rotation speed R is small, so that braking control faithful to the driver's brake pedal depression amount F is ensured from the viewpoint of ensuring drivability and safety. This is because the additional regenerative braking torque Tad is suppressed.

  FIG. 4B shows the relationship between the additional regenerative braking torque Tad and the motor rotational speed R when the gear position of the transmission 5 is set to “third speed”. In this case, compared with FIG. 4A, the general behavior of the additional regenerative braking torque Tad with respect to the change in the motor rotational speed R is similar, but the additional regenerative braking torque Tad is set to be small as a whole. ing. In other words, since the vehicle speed is assumed to decrease (approach to the stopped state) when the gear position of the transmission 5 becomes low, the faithfulness to the driver's brake pedal depression amount F is ensured from the viewpoint of ensuring drivability and safety. This is because the additional regenerative braking torque Tad is suppressed so that accurate braking control is possible. As a result, when the gear position is on the low speed side, the additional regenerative braking torque Tad is reduced, so that braking control faithful to the driver's brake pedal depression operation is possible, and drivability can be improved.

  FIG. 4C shows the relationship between the additional regenerative braking torque Tsr and the motor rotational speed R when the gear position of the transmission 5 is set to “first speed” or “second speed”. In this case, the additional regenerative braking torque Tsr is always set to zero regardless of the motor rotational speed R. This is because it is assumed that the vehicle is in a state closer to the stop state at a lower speed than in FIG. 4B, so the additional regenerative braking torque Tad is set to zero and the brake pedal of the driver is set as much as possible. This is because braking control faithful to the stepping action is possible, and safety is improved.

  The correspondence relationship between the additional regenerative braking torque Tsr and the motor rotational speed R at each gear stage shown in FIG. 4 is set in advance by a theoretical, experimental, or simulation method, and stored in a memory or the like built in the vehicle ECU 26. Stored in advance.

Returning to FIG. 2 again, the vehicle ECU 26 determines whether the sum of the reference regenerative torque calculated in step S104 and the additional regenerative torque calculated in step S105 is equal to or less than the maximum regenerative braking torque Tm of the motor 4. (Step S106). As shown by the point (a) in FIG. 3, when the sum is equal to or less than the maximum regenerative braking torque Tm of the motor 4 (step S106: YES), the vehicle ECU 26 sets the regenerative braking torque Tr based on the following equation ( Step S107).
Regenerative braking torque Tr = reference regenerative braking torque Tsr + additional regenerative braking torque Tad (1)
Then, the vehicle ECU 26 performs regenerative control of the motor 4 so that the regenerative braking torque Tr calculated by the equation (1) is generated (step S108). Thus, by calculating the regenerative braking torque Tr by adding the regenerative braking torque Tad to the reference regenerative braking torque Tsr, it is possible to improve the recovery efficiency of regenerative energy during deceleration. In particular, since the additional regenerative braking torque Tad is set according to the vehicle running conditions (motor rotation speed R and gear stage S), the reference regenerative braking torque Tsr is set to be relatively small in order to prevent deterioration of drivability. Even in this case, good energy recovery efficiency can be obtained.

On the other hand, when the sum is larger than the maximum regenerative braking torque Tm of the motor 4 (step S106: NO) as shown by a point (b) in FIG. 3, the vehicle ECU 26 sets the regenerative braking torque Tr based on the following equation. (Step S109).
Regenerative braking torque Tr = Maximum regenerative braking torque Tm (2)
Then, the vehicle ECU 26 regeneratively controls the motor 4 so as to generate the regenerative braking torque Tr calculated by the equation (2), connects the clutch, and applies the engine brake (step S110). In this case, since the regenerative braking torque Tr exceeds the maximum regenerative braking torque Tm that can be generated by the motor, the maximum regenerative braking torque Tm is generated from the motor to obtain the maximum regenerative energy and the insufficient braking force. Is compensated by engine brake.

  In step S110, the shortage of the regenerative braking torque of the motor is compensated by the engine brake, but it may be compensated by automatic control of a mechanical brake instead of the engine brake.

  As described above, in the hybrid electric vehicle 1 according to the present invention, even when the reference regenerative braking torque is set to be relatively small in order to prevent the drivability from being deteriorated, the vehicle running conditions (the number of rotations of the motor) By adding the additional regenerative braking torque that is set according to the transmission speed of the transmission), it is possible to obtain good energy recovery efficiency.

  The present invention relates to a hybrid electric vehicle that travels with power output from at least one of an internal combustion engine and an electric motor that uses power stored in a battery as a power source, and that generates a regenerative braking torque during regeneration of the electric motor and decelerates. The control device can be used.

DESCRIPTION OF SYMBOLS 1 Hybrid electric vehicle 2 Engine 3 Clutch 4 Motor 5 Transmission 9 Drive wheel 11 Battery 13 Brake pedal 14 Accelerator pedal 26 Vehicle ECU
27 Engine ECU
28 Inverter ECU
29 Battery ECU

Claims (4)

By driving the motive power output from at least one of the internal combustion engine and an electric motor powered by using the electric power stored in the battery as a motive power source through a transmission to drive wheels, and driving the electric motor regeneratively A control device for a hybrid electric vehicle that transmits a regenerative braking torque to the drive wheels to decelerate,
Brake pedal depression amount detection means for detecting the depression amount of the brake pedal,
A rotational speed detection means for detecting the rotational speed of the electric motor;
Shift speed detecting means for detecting a shift speed of the transmission;
A reference regenerative braking torque of the electric motor is calculated based on the detected rotation speed of the electric motor and the detected gear position, and the sum of the calculated reference regenerative braking torque and the added regenerative braking torque is the value of the electric motor. By adding the added regenerative braking torque calculated based on the detected amount of depression of the brake pedal, the number of rotations of the electric motor and the gear position to the reference regenerative braking torque when the maximum regenerative braking torque is not reached, Regenerative braking torque calculating means for calculating regenerative braking torque, and
The additional regenerative braking torque increases from the first rotation speed to a second rotation speed higher than the first rotation speed, and from the second rotation speed to a third rotation speed higher than the second rotation speed. A control apparatus for a hybrid electric vehicle, which is set to decrease and is set to zero in a range smaller than the first rotation speed .   2. The control apparatus for a hybrid electric vehicle according to claim 1, wherein the additional regenerative braking torque is set to decrease as the gear position of the transmission decreases. The plus regenerative braking torque, the control device for a hybrid electric vehicle according to claim 1, characterized in that the depression amount of the brake pedal is set to increase in accordance with increase. When the reference regenerative torque is greater than the maximum regenerative braking torque, the regenerative braking torque is set to the maximum regenerative braking torque, and a clutch provided between the output shaft of the internal combustion engine and the input shaft of the electric motor is provided. The control device for a hybrid electric vehicle according to any one of claims 1 to 3 , wherein the controller is connected and decelerated by applying an engine brake by the internal combustion engine.

Images