JP7139073B2 - Hybrid vehicle control device - Google Patents

Description

The present invention relates to a control device for controlling a hybrid vehicle equipped with an electric motor for running and an internal combustion engine.

2. Description of the Related Art Recently, hybrid vehicles equipped with two types of power sources, an electric motor and an internal combustion engine, are gaining popularity. A series-type hybrid vehicle (see, for example, the following patent document) generates power by driving a motor generator for power generation with an internal combustion engine, and stores the generated power in a power storage device, such as a lithium ion secondary battery or a nickel metal hydride secondary battery. It is stored in a battery and/or a capacitor, etc., and supplied to a motor-generator for running. Then, the driving wheels of the vehicle are rotated by the motor generator for traveling to travel.

Not only the motor-generator for power generation but also the motor-generator for traveling can generate power by regenerative braking, and the generated power can be stored in the power storage device. When electric charge is already stored up to the capacity of the power storage device, the electric power obtained by regenerative braking is intentionally supplied to the motor generator for power generation, and this is operated as an electric motor to perform motoring to rotationally drive the internal combustion engine. This consumes excess power.

In a hybrid vehicle, the vehicle can be driven by the rotational driving force output from the motor generator for traveling without firing the internal combustion engine to generate the rotational driving force by burning the fuel. Therefore, even during operation of the vehicle, the state where the rotation of the internal combustion engine is stopped may continue.

When the amount of electric charge stored in the power storage device decreases, or when the required output of the traction motor generator is large, the internal combustion engine is started, fuel is supplied to the cylinders, and the fuel is combusted, and the internal combustion engine outputs rotational drive. The electric power is used to drive the electric power generation motor generator, and electric power is generated to charge the power storage device or increase electric power supplied to the running motor generator.

In a series-system hybrid vehicle, the motor generator for power generation also serves to motor (or crank) the internal combustion engine in preparation for starting the stopped internal combustion engine. During motoring, the required power is supplied from the power storage device.

JP 2019-131035 A

Conventionally, for the purpose of reducing the operation force required for braking a vehicle, that is, the force applied to the brake pedal, the force is boosted by utilizing the intake negative pressure generated downstream of the throttle valve in the intake passage of an internal combustion engine. A vacuum booster (vacuum type) brake booster is widely used.

The negative pressure stored in the brake booster is consumed when the vehicle driver steps on the brake pedal. As already described, the hybrid vehicle can run with the internal combustion engine stopped. While the rotation of the internal combustion engine is stopped, the intake negative pressure cannot be supplied to the brake booster. Therefore, when the negative pressure stored in the brake booster decreases to the lower limit threshold value, the internal combustion engine is motored or fired to generate an intake negative pressure, and the negative pressure is supplied to the brake booster so that the brake booster is , the negative pressure stored in is restored to the upper limit threshold value.

During the period in which the negative pressure of the brake booster is restored by the motoring of the internal combustion engine, the electric power stored in the power storage device is consumed by the electric motor for motoring, and the electric power that can be supplied from the power storage device to the electric motor for running is reduced accordingly. Decrease. As a result, even if the driver depresses the accelerator pedal to request acceleration of the vehicle, there is a concern that the acceleration performance desired by the driver cannot be obtained. This problem manifests itself particularly when the capacity of the power storage device is small.

Even if the internal combustion engine is fired to recover the negative pressure of the brake booster, it is necessary to reduce the opening of the throttle valve, which is the intake throttle valve, in order to obtain a large intake negative pressure. The amount of intake air and the amount of fuel injected decrease, and the output of the internal combustion engine decreases. Ultimately, it is not possible to direct a large amount of power to the drive wheels for driving the vehicle, and acceleration is limited.

SUMMARY OF THE INVENTION The present invention, which has been made in view of the above, aims at achieving compatibility between ensuring negative pressure to be stored in the brake booster and accelerating performance of the vehicle.

In the present invention, the driving force for power generation can be supplied to the driving motor capable of supplying the driving force for driving to the driving wheels, and the generator generating the electric power to be supplied to the driving motor, or the driving force for driving can be supplied to the driving wheels. a brake booster that stores the intake negative pressure generated downstream of the throttle valve in the intake passage of the internal combustion engine and uses the negative pressure to boost the brake pedal force; and a motoring electric motor capable of supplying driving force for rotating the internal combustion engine, the control device for controlling a hybrid vehicle, wherein when the negative pressure stored in the brake booster falls below a lower limit threshold, the motor Motoring, which rotates the internal combustion engine by the ring electric motor, or firing, which supplies fuel to the internal combustion engine to start and rotate it, restores the negative pressure stored in the brake booster to the upper threshold value, which is higher than the lower threshold value. The motoring or firing is continued until the negative pressure recovers above the upper threshold, and the motoring or firing is terminated on the condition that the negative pressure recovers above the upper threshold, indicating the driver's intention to accelerate the vehicle. A control device for a hybrid vehicle is configured that lowers the upper limit threshold when a predetermined acceleration request condition is satisfied, compared to when it is not. More specifically, the degree of opening of the accelerator operated by the driver is greater than or equal to a predetermined value, the required output corresponding to the degree of accelerator opening and vehicle speed is greater than or equal to a predetermined value, or the output and rotation speed of the traction motor It is conceivable that the upper limit threshold value is lowered when the amount of increase in the applied current or applied voltage per unit time is greater than or equal to a predetermined value, assuming that the acceleration requirement is met. In any case, it is preferable that the upper limit threshold is set to a value equal to or greater than the minimum amount of negative pressure required to brake a running vehicle.

When the acceleration request condition is satisfied and the negative pressure stored in the brake booster recovers to the upper limit threshold value or more due to the motoring of the internal combustion engine, the motoring is terminated and the electric storage device mounted on the vehicle is used to supply the electric motor for traveling. It is preferable to increase the power supplied to the . That is, by supplying the electric power that has been supplied to the motoring motor until the end of the motoring to the driving motor, the driving force output by the driving motor is increased.

When the acceleration request condition is satisfied and the negative pressure stored in the brake booster recovers to the upper limit threshold value or more due to the motoring of the internal combustion engine, if the accelerator opening is the judgment value or more, motoring is stopped. It is also possible to move to firing, perform power generation by the generator, and if the accelerator opening is less than the judgment value, end the motoring and stop the rotation of the internal combustion engine. In a situation where the driver is requesting high acceleration and the required output of the traction motor is large, the internal combustion engine is quickly started and switched to firing, and the electric power generated by the generator is supplied to the traction motor. to increase the driving force output by the driving motor.

Advantageous Effects of Invention According to the present invention, in a hybrid vehicle, it is possible to ensure both the negative pressure stored in the brake booster and the acceleration performance of the vehicle.

1 is a diagram showing a schematic configuration of a series hybrid vehicle and a control device according to an embodiment of the present invention; FIG. The figure which shows the outline|summary of the internal combustion engine mounted in the hybrid vehicle of the same embodiment. FIG. 4 is a diagram showing the classification of the required output in the control performed by the control device of the embodiment; FIG. 4 is a flow diagram showing an example of the procedure of processing executed by the control device according to the embodiment according to the program; FIG. 4 is a flow diagram showing an example of the procedure of processing executed by the control device according to the embodiment according to the program; FIG. 4 is a timing chart illustrating how control is performed by the control device of the embodiment; FIG. 4 is a timing chart illustrating how control is performed by the control device of the embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of main systems of a hybrid vehicle in this embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generating motor generator 2 that is driven by the internal combustion engine 1 to generate power, a power storage device 3 that stores the electric power generated by the power generating motor generator 2, the power generating motor generator 2 and/or Alternatively, it is provided with a traveling motor generator 4 that receives electric power supply from the power storage device 3 to drive the driving wheels 62 of the vehicle.

The hybrid vehicle of the present embodiment is a series hybrid electric vehicle that uses the internal combustion engine 1 only for power generation, and the drive wheels 62 of the vehicle are exclusively supplied with driving force for running from the motor generator 4 for running. The internal combustion engine 1 and the drive wheels 62 are mechanically separated from each other, and originally rotational driving force is not transmitted between them. In other words, the internal combustion engine 1 can rotate completely independently of the motor generator 4 for traveling and the drive wheels 62, and can stop completely independently. Therefore, during operation of the vehicle in which the ignition switch (power switch or ignition key) is turned on, even if the vehicle is in a state in which the vehicle can run by depressing the accelerator pedal, the power storage device 3 is sufficiently charged. Under the condition that the electric charge is accumulated and the brake booster 15 has accumulated a sufficient negative pressure, the operation of the internal combustion engine 1 involving fuel combustion may not be performed.

A crankshaft, which is a rotating shaft of the internal combustion engine 1, is mechanically connected to a rotating shaft of a motor generator 2 for power generation via a gear mechanism. By inputting the rotational driving force output by the internal combustion engine 1 to the electric power generating motor generator 2, the electric power generating motor generator 2 generates electric power. The generated electric power is charged in the power storage device 3 and/or supplied to the traveling motor generator 4 . The power generation motor generator 2 also functions as an electric motor for motoring, which itself generates rotational driving force to rotationally drive the crankshaft of the internal combustion engine 1 . For example, the power generation motor generator 2 performs motoring (cranking) as preparation for starting the stopped internal combustion engine 1 .

The running motor generator 4 generates driving force for running the vehicle, and inputs the driving force to the drive wheels 62 via the speed reducer 61 . In addition, the running motor generator 4 rotates together with the drive wheels 62 to generate electric power, and recovers the kinetic energy of the vehicle as electric energy. The electric power generated by this regenerative braking charges the power storage device 3 .

Of course, if electric charge is already stored up to the capacity of the power storage device 3 and further charging is difficult, the electric power regenerated by the traveling motor generator 4 is intentionally supplied to the electric power generating motor generator 2 to generate electric power. The internal combustion engine 1 is rotationally driven by operating the motor generator 2 as an electric motor. This consumes excess electric power while maintaining the braking performance of the vehicle. Further, at this time, since the rotation of the internal combustion engine 1 is maintained, fuel cut can be executed to temporarily stop the supply of fuel to the cylinders of the internal combustion engine 1 .

The power generator inverter 21 converts the AC power generated by the power generation motor generator 2 into DC power. Then, the DC power is input to power storage device 3 or drive inverter 41 . In addition, when the power generation motor generator 2 is operated as an electric motor, the power generator inverter 21 converts the DC power supplied from the power storage device 3 and/or the drive inverter 41 into AC power, and then converts the power generation motor generator 2 into AC power. to enter.

The drive inverter 41 converts the DC power supplied from the power storage device 3 and/or the generator inverter 21 into AC power and inputs the AC power to the motor generator 4 for running. In addition, the drive inverter 41 converts AC power generated by the traveling motor generator 4 when the vehicle is regeneratively braked into DC power and inputs the DC power to the power storage device 3 or the generator inverter 21 . The generator inverter 21 and the drive inverter 41 form part of a PCU (Power Control Unit).

The power storage device 3 is a battery and/or a capacitor or the like. The battery is a high-voltage secondary battery with high energy density, such as a lithium-ion secondary battery or a nickel-hydrogen secondary battery. The power storage device 3 charges and stores electric power generated by each of the motor generator 2 for power generation and the motor generator 4 for running. Power storage device 3 also discharges electric power for operating motor generator 2 for electric power generation and motor generator 4 for running as electric motors, and supplies necessary electric power to motor generators 2 and 4 .

FIG. 2 shows an outline of the internal combustion engine 1 mounted on the hybrid vehicle of this embodiment. The internal combustion engine 1 is a spark-ignited four-stroke engine, and includes a plurality of cylinders 11 (eg, three cylinders, one of which is shown in FIG. 1). An injector 111 for injecting fuel toward the intake port is provided near the intake port of each cylinder 11 . A spark plug 112 is attached to the ceiling of the combustion chamber of each cylinder 11 . The spark plug 112 receives an induced voltage generated by the ignition coil and induces spark discharge between the center electrode and the ground electrode.

An intake passage 13 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 11 . An air cleaner 131, an electronic throttle valve 132, a surge tank 133, and an intake manifold 134 are arranged in this order on the intake passage 13 from upstream. The air cleaner 131 is located at the most upstream position in the intake passage 13, that is, at the intake port that takes in air. The air intake opens to the front of the vehicle to take in cool air and increase the charging efficiency of the internal combustion engine.

An exhaust passage 14 for exhausting exhaust guides the exhaust generated as a result of burning fuel in the cylinder 11 from the exhaust port of each cylinder 11 to the outside. An exhaust manifold 142 and a three-way catalyst 141 for purifying exhaust gas are arranged on the exhaust passage 14 .

An external EGR (Exhaust Gas Recirculation) device 12 implements so-called high pressure loop EGR. The EGR device 12 includes an external EGR passage 121 that communicates the upstream side of the catalyst 141 in the exhaust passage 14 and the downstream side of the throttle valve 132 in the intake passage 13, an EGR cooler 122 provided on the EGR passage 121, and the EGR passage 121. and an EGR valve 123 that opens and closes the EGR passage 121 to control the flow rate of EGR gas flowing through the EGR passage 121 . The inlet of the EGR passage 121 is connected to the exhaust manifold 142 in the exhaust passage 14 or a predetermined location downstream thereof. An outlet of the EGR passage 121 is connected to a predetermined location downstream of the throttle valve 132 in the intake passage 13 , specifically, a surge tank 133 .

The internal combustion engine 1 is provided with a brake booster 15 for reducing the operating force required for braking the vehicle, that is, the force applied to the brake pedal. The brake booster 15 introduces intake negative pressure from a portion (or a surge tank 133) downstream of the throttle valve 132 in the intake passage 13, and uses the negative pressure to boost the depression force of the brake pedal. It is widely known. The brake booster 15 has a constant pressure chamber (negative pressure chamber) that stores negative pressure and a variable pressure chamber (atmospheric pressure chamber) to which atmospheric pressure is applied. ing. The negative pressure line 151 guides the intake negative pressure on the downstream side of the throttle valve 132 to the constant pressure chamber. A check valve 152 is provided on the negative pressure line 151 to retain the negative pressure in the constant pressure chamber and prevent the positive pressure from being applied to the constant pressure chamber.

When the driver does not operate the brake pedal, the constant pressure chamber communicates with the variable pressure chamber, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the constant pressure chamber and the variable pressure chamber are cut off, and air is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes the control pressure that boosts the force applied to the brake pedal. The brake depression force amplified by the brake booster 15 is converted into hydraulic pressure in the master cylinder 16 . The master cylinder pressure output by the master cylinder 16, that is, the pressure of the brake fluid discharged by the master cylinder 16 is transmitted to a brake device such as a brake caliper or a wheel cylinder via a hydraulic circuit, and is used for braking the vehicle by the brake device. Used.

An ECU (Electronic Control Unit) 0, which is a control device for controlling the internal combustion engine 1, the motor generator 2 for power generation, the power storage device 3, the inverters 21 and 41, and the motor generator 4 for running, includes a processor, a memory, an input interface, an output interface, and the like. It is a microcomputer system having The ECU 0 includes a plurality of ECUs, that is, an EFI (Electronic Fuel Injection) ECU 01 that controls the internal combustion engine 1 , a generator ECU 02 that controls the power generation motor generator 2 and the generator inverter 21 , and a BMS (Battery Management) that controls the power storage device 3 . System) ECU 03, driving machine ECU 04 for controlling the traveling motor generator 4 and driving machine inverter 41, etc., and HV (Hybrid Vehicle) ECU, which is a higher-level controller that controls them, are connected to CAN (Controller Area Network), etc. are connected so as to be able to communicate with each other via an electric communication line.

For the ECU 0, a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine 1 and the engine speed , the accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal by the driver as the accelerator opening (in other words, the driving force requested by the driver to the vehicle), and the driver pressing the brake pedal. A brake depression amount signal output from a switch that detects depression, a sensor that detects the amount of depression of the brake pedal by the driver, or a sensor that detects master cylinder pressure, which is the pressure of the brake fluid discharged from the master cylinder 16. d, an intake air temperature/pressure signal e output from a temperature/pressure sensor that detects the intake air temperature and pressure in the intake passage 13 (especially the surge tank 133), and a water temperature that detects the temperature of the cooling water of the internal combustion engine 1 A cooling water temperature signal f output from a sensor, a battery SOC (State Of Charge) signal g output from a sensor (in particular, a battery current and/or battery voltage sensor) that detects the amount of charge stored in the power storage device 3, and a brake. A negative pressure signal h or the like output from a negative pressure sensor that detects negative pressure stored in the constant pressure chamber of the booster 15 is input.

Then, the ECU 0 senses through various sensors the accelerator opening degree operated by the driver, the shift position, that is, the position of the shift lever or the selector lever, the current vehicle speed, the gradient of the road surface, and the power storage device 3. The rotational driving force output by the motor-generator 4 for traveling and the output by the internal combustion engine 1 are determined according to the amount of stored charge, the magnitude of the negative pressure stored in the brake booster 15, the power generated by the motor-generator 2 for power generation, and the like. It controls the increase/decrease of the rotational driving force to be generated and the magnitude of the electric power generated by the power generation motor generator 2 .

In principle, if the power storage device 3 is currently storing a sufficient amount of electric charge and the required output of the traction motor generator 4 is small, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is operated. do not do. On the other hand, if the amount of electric charge stored in the power storage device 3 falls below the threshold value, or if the required output of the motor-generator 4 for traveling is large, the internal combustion engine 1 is started and fuel is supplied to the cylinders. , drives the generator motor generator 2 with the rotational driving force output from the internal combustion engine 1, performs power generation to charge the storage device 3, or electric power supplied to the motor generator 4 for running enhance the

FIG. 3 shows the relationship between the output requested by the driver of the vehicle and whether or not the internal combustion engine 1 and the motor/generator 2 should be operated. The required output is determined by the degree of opening of the accelerator operated by the driver and the vehicle speed. The driving force to be applied to the drive wheels 62 increases as the accelerator opening increases. The required output increases as the driving force to be applied to the drive wheels 62 increases, and increases as the vehicle speed increases. In FIG. 3, the required output increases toward the upper right.

In a low output region I where the driving force to be applied to the drive wheels 62 is relatively small and the vehicle speed is also relatively low, the ECU 0 stops the operation of the internal combustion engine 1 without supplying fuel, and causes the power generation motor generator 2 to generate power. Do not operate as a machine. In the low output region I, the traveling motor generator 4 receives electric power supply only from the power storage device 3 and outputs driving force for traveling the vehicle. The low output region I is typically when the accelerator opening is 0 or less than a predetermined value, or when the vehicle is decelerating.

On the other hand, the ECU 0 supplies fuel to the internal combustion engine 1 to operate it in medium and high power ranges II and III, in which the driving force to be applied to the drive wheels 62 is greater than a certain level or the vehicle speed is higher than a certain level. The generator 2 is operated as a power generator. In the medium output region II where the required output is not significantly high, the motor generator 4 for traveling receives power supply mainly from the motor generator 2 for power generation, and outputs driving force for traveling the vehicle. At this time, a small amount of power is supplied from the power storage device 3, or no power is supplied at all. In the high output region III where the required output is remarkably high, the traveling motor generator 4 receives power supply from both the electric power generating motor generator 2 and the power storage device 3, and outputs driving force for traveling the vehicle.

The internal combustion engine 1 is started while the fuel is not being supplied to the cylinders of the internal combustion engine 1 and the internal combustion engine 1 is not being operated, and the drive wheels 62 are being driven by the traveling motor generator 4 to drive the vehicle. In order to execute power generation by the motor generator 2 for power generation, first, the motor generator 2 for power generation is operated as an electric motor, thereby performing motoring for starting the internal combustion engine 1 . Then, the crankshaft of the internal combustion engine 1 rotates a predetermined number of times or more or a predetermined angle or more, and after completion of cylinder discrimination for obtaining the current stroke or piston position of each cylinder of the internal combustion engine 1, each cylinder of the internal combustion engine 1 rotates. To inject fuel at an appropriate timing in accordance with a stroke, and to start firing for igniting and burning the fuel at an appropriate timing. The rotation angle and rotation speed of the crankshaft of the internal combustion engine 1, i.e., the engine speed, can be detected (in the generator ECU 02) via a resolver attached to the motor generator 2 for power generation. It can also be detected via a sensor (at EFI ECU01).

When the internal combustion engine 1 rotates independently and can output the rotational driving force necessary for power generation, in other words, even if the output of the motor generator 2 for power generation is reduced, the engine speed does not tend to increase. When it can be maintained, the output of the motor generator 2 for power generation, which is operated as an electric motor, is reduced to 0 to end the motoring, and the motor generator 2 for power generation is rotationally driven by the internal combustion engine 1 this time. Furthermore, the power generation motor generator 2 is operated as a power generator, and the generated power is increased from zero.

Thus, the intake air amount and the fuel injection amount supplied to the cylinder 1 of the internal combustion engine 1 and the electric power generated by the motor generator 2 are adjusted to increase or decrease so that the engine speed follows the target speed, which is increased in stages. Implement feedback control. The final target engine speed is the engine speed at which the internal combustion engine 1 can be operated at optimum or near-optimal efficiency and which is most advantageous for the fuel consumption rate, or at which the internal combustion engine 1 produces maximum torque or maximum output or torque or output close thereto. Set the rpm that you can achieve.

Incidentally, the EFI ECU 01 forming a part of the ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for the operation control of the internal combustion engine 1 through an input interface, and calculates the engine speed. is obtained, and the amount of air taken into the cylinder 11 is estimated. Then, the required fuel injection amount (necessary for realizing the target air-fuel ratio) matching the intake air amount, fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing (one time It determines operating parameters of the internal combustion engine 1 such as the number of ignitions for combustion), the required EGR rate (or EGR gas amount), and the like. The EFI ECU 01 outputs various control signals i, j, k, l corresponding to operating parameters to the igniter of the spark plug 112, the injector 111, the throttle valve 132, the EGR valve 123, etc. via an output interface.

However, as shown in FIG. 4, the ECU 0 determines that the negative pressure currently stored in the brake booster 15 (especially under the condition that the vehicle is running with the rotation of the internal combustion engine 1 stopped) reaches the lower limit threshold. When it falls below (step S1), motoring is performed to rotate the crankshaft of the internal combustion engine 1 by the motor generator 2 for power generation (step S2) regardless of the magnitude of the current required output. When the crankshaft of the internal combustion engine 1 is rotated to move the pistons and intake/exhaust valves of each cylinder 1, intake air flows through the intake passage 13, and intake negative pressure is generated downstream of the throttle valve 132, which is an intake throttle valve. generated and the negative pressure can be replenished to the constant pressure chamber of the brake booster 15 . In step S2, instead of motoring the internal combustion engine 1, it is possible to start the internal combustion engine 1, supply fuel to the cylinders 11, and execute firing for autonomously rotating the crankshaft.

The motoring (or firing, step S2) of the internal combustion engine 1 for supplying the intake negative pressure to the brake booster 15 is continued until the negative pressure stored in the brake booster 15 recovers to the upper limit threshold or more (step S3). continue. Naturally, the upper limit threshold in step S3 is higher than the lower limit threshold in step S2.

In addition, as shown in FIG. 5, the ECU 0 of the present embodiment suggests the driver's intention to accelerate the vehicle with respect to the upper threshold value to be compared with the negative pressure stored in the brake booster 15 in step S3. If the predetermined acceleration request condition is satisfied (step S0), the upper limit threshold value is lowered (step S8) as compared with the case otherwise (step S9).

During motoring of the internal combustion engine 1 , a large amount of electric power is supplied from the power storage device 3 to the power generating motor generator 2 that rotationally drives the internal combustion engine 1 . Since the amount of power output from power storage device 3 is finite, the power that can be supplied from power storage device 3 to motor generator 4 for traveling is reduced by the amount consumed by motor generator 2 for power generation. Of course, while the internal combustion engine 1 is motoring, the electric power generation motor generator 2 cannot generate electric power. Therefore, even though the driver requests acceleration of the vehicle, the driving motor generator 4 cannot output a necessary and sufficient amount of driving force, and the desired acceleration performance cannot be obtained. There is a concern that the problem of deterioration of performance or drive feeling will be caused. This problem manifests itself when the capacity of the power storage device 3 mounted on the vehicle and the power that can be output are small.

Even if the internal combustion engine 1 is fired and the negative pressure is supplied to the brake booster 15, it is necessary to narrow the opening of the throttle valve 132 in order to obtain a large intake negative pressure. As a result, the output of the internal combustion engine 1 decreases. As a result, the electric power that can be generated by the motor generator 2 for power generation is reduced, and the electric power supplied to the motor generator 4 for running cannot be expected to increase.

Therefore, in the present embodiment, when the acceleration request condition is satisfied (step S0), the upper limit threshold value is set to a lower value to advance the timing at which the condition of step S3 becomes true, and the negative pressure is applied to the brake booster 15. is terminated as early as possible. As a result, the time at which the electric power supplied to the traveling motor generator 4 can be increased is advanced, and the vehicle can be accelerated in accordance with the intention of the driver.

The acceleration requirement in step S0 is, for example, that the accelerator opening degree operated by the driver is greater than or equal to a predetermined value, or that the required output corresponding to the accelerator opening degree and vehicle speed is greater than or equal to a predetermined value. Alternatively, the acceleration request condition is established when the amount of increase per unit time such as the output of the running motor generator 4, the number of rotations (which may be that of the drive wheels 62), the applied current or the applied voltage is greater than a predetermined value. It can be a thing.

The upper limit threshold to be compared with the negative pressure stored in the brake booster 15, which is set in step S8, may be set to be equal to or larger than the minimum required negative pressure for suitably braking the running vehicle. preferable. For example, the upper limit threshold is set to a negative pressure that is consumed until the driver depresses the brake pedal once to stop the running vehicle, in other words, it is set to a value equal to or higher than the negative pressure used for braking once. . The upper limit threshold set in step S8 may be variably adjusted according to the current accelerator opening, vehicle speed, and the like. The upper threshold set in step S9 is larger than the upper threshold set in step S8 and is equal to or greater than the sum of the negative pressures used for braking twice or more.

In step S3, when the negative pressure stored in the brake booster 15 recovers to the upper limit threshold or more, the subsequent processing is selected according to the accelerator opening at that time or the magnitude of the required output for the motor generator 4 for traveling. do. If the acceleration request condition is not satisfied (step S0), for example, if the accelerator opening is smaller than a predetermined value or the required output is smaller than a predetermined value, the motoring of the internal combustion engine 1 by the motor generator 2 for power generation is stopped. (step S7) to stop the rotation of the internal combustion engine 1 and the motor generator 2 for power generation.

If the accelerator opening is greater than or equal to a predetermined value but less than the determination value, or if the required output is greater than or equal to the predetermined value but less than the determination value (step S4), motoring of the internal combustion engine 1 by the motor generator 2 for power generation is started. is stopped, and part or all of the electric power that has been supplied from the power storage device 3 to the motor-generator 2 for power generation is supplied to the motor-generator 4 for travel (step S6). That is, the electric power supplied from the power storage device 3 to the traveling motor generator 4 is increased from before, and the driving force output from the traveling motor generator 4 and input to the drive wheels 62 is increased. The determination value referred to in step S4 is a value higher than the predetermined value referred to in step S0.

If the accelerator opening is larger than the judgment value or the required output is larger than the judgment value (step S4), the motoring of the internal combustion engine 1 by the motor generator 2 for power generation is started to make the internal combustion engine 1 independent. At the same time, the power generation motor generator 2 is operated as a power generator to generate power, and part or all of the generated power is supplied to the running motor generator 4 (step S5). . That is, the electric power supplied to the traveling motor-generator 4 is further increased compared to step S6, and the driving force output from the traveling motor-generator 4 and input to the driving wheels 62 is further enhanced. In step S5, compared to step S2, the opening degree of the throttle valve 132 is further increased to increase the intake air amount and the fuel injection amount charged into the cylinder 11. FIG.

The determination value in step S4 defines the magnitude relationship between the power that can be output by the power storage device 3 at present and the output that is currently requested from the motor-generator 4 for traveling. In other words, if the accelerator opening or the required output is smaller than the judgment value, it means that the electric power that can be output by the power storage device 3 exceeds the required output for the motor generator 4 for traveling, and the electric power is not generated by the motor generator 2 for power generation. , means that the electric power required for accelerating the vehicle can be supplied to the traveling motor generator 4 only from the power storage device 3 . On the other hand, if the accelerator opening or the required output is larger than the judgment value, it means that the electric power that can be output from the power storage device 3 is lower than the required output for the traveling motor generator 4, and the power generating motor generator 2 must generate power. For example, it means that the electric power required for accelerating the vehicle cannot be supplied to the traveling motor generator 4 .

In step S6 or S7, instead of stopping the rotation of the internal combustion engine 1, the engine may be started and fired in an idling or low load region close to idling. In an idling or low-load operating region, the opening of the throttle valve 132 is reduced to the minimum required, and a large intake negative pressure is generated downstream of the throttle valve 132 in the intake passage 13 . By applying this intake negative pressure, the brake booster 15 can store a negative pressure higher than the upper limit threshold lowered in step S8.

6 and 7 show patterns of control executed by the ECU 0 of this embodiment. In FIGS. 6 and 7, time _t0 is the time when the negative pressure stored in the brake booster 15 has decreased to the lower limit threshold, that is, the motoring of the internal combustion engine 1 is started to replenish the negative pressure in the brake booster 15. It is time. A dashed line represents an upper limit threshold to be compared with the negative pressure stored in the brake booster 15, which is appropriately raised or lowered by the ECU 0 of the present embodiment.

Assuming that the upper threshold is not lowered through steps S0 and S8 shown in FIG. Motoring continues and does not end until _time t2 when the negative pressure stored in the brake booster 15 increases significantly. 6 and 7, the output of the traveling motor-generator 4 is restricted for a long period of _time from time _t0 to time t2, and the driver's Desired acceleration performance cannot be achieved.

However, if the _upper threshold is lowered through steps S0 and S8, the motoring can be terminated at time t1 when the negative pressure stored in the brake booster 15 recovers to the minimum required level for subsequent braking of the vehicle. . After time t1, the output of the traveling motor generator ₄ can be increased to achieve the acceleration performance desired by the driver. FIG. 6 exemplifies a case where step S6 of stopping the rotation of the internal combustion engine ₁ and the power generation motor generator 2 is performed after time t1. FIG. 7 exemplifies a case where step S5 is executed in which the internal combustion engine ₁ is fired and the electric power generation motor generator 2 is used to generate electric power after time t1.

In the present embodiment, the driving motor 4 that can supply driving force for driving to the drive wheels 62, and the internal combustion engine that can supply the driving force for power generation to the generator 2 that generates electric power to be supplied to the driving motor 4 an engine 1; a brake booster 15 that stores intake negative pressure generated downstream of a throttle valve 132 in an intake passage 13 of the internal combustion engine 1 and utilizes the negative pressure to boost the brake depression force; A control device 0 for controlling a hybrid vehicle comprising a motoring electric motor 2 capable of supplying a driving force for rotating a brake booster 1, when the negative pressure stored in the brake booster 15 falls below the lower limit threshold, The motoring that rotates the internal combustion engine 1 by the motoring electric motor 2 or the firing that supplies fuel to the internal combustion engine 1 to start and rotate it, and the negative pressure stored in the brake booster 15 is higher than the lower limit threshold. The motoring or firing is continued until the vehicle recovers to the upper limit threshold or more, and if a predetermined acceleration request condition that indicates the driver's intention to accelerate the vehicle is satisfied, compared to the case that it is not. A control device 0 for a hybrid vehicle that lowers the upper limit threshold is configured.

According to this embodiment, when the internal combustion engine 1 is motored or fired for the purpose of supplying negative pressure to the brake booster 15, if the driver indicates his intention to accelerate the vehicle, his intention Accordingly, the motoring or firing can be terminated early, and the driving force supplied to the drive wheels 62 can be increased as quickly as possible to achieve the acceleration desired by the driver.

When the acceleration request condition is satisfied and the negative pressure stored in the brake booster 15 recovers to the upper limit threshold value or more due to the motoring of the internal combustion engine 1, the motoring is terminated and the on-vehicle power storage device 3 The electric power supplied to the traveling electric motor 4 can be increased more than before. That is, by supplying the electric power that has been supplied to the motoring motor 2 before the end of motoring to the traveling electric motor 4, the driving force output by the traveling electric motor 4 is increased.

Further, when the acceleration request condition is satisfied and the negative pressure stored in the brake booster 15 is restored to the upper limit threshold value or more by the motoring of the internal combustion engine 1, if the accelerator opening is the judgment value or more, For example, the motoring is shifted to firing to generate power by the generator 2, and if the accelerator opening is less than the judgment value, the motoring is terminated and the rotation of the internal combustion engine 1 is stopped. In a situation where the driver is requesting high acceleration and the required output of the traction motor 4 is large, the internal combustion engine 1 is quickly started and switched to firing, and the electric power generated by the generator 2 is supplied to the traction motor. 3 to further increase the driving force output by the driving motor 3. In a situation where the driver does not request a very high acceleration and the required output for the traveling electric motor 4 is not so large, the internal combustion engine 1 and the motoring electric motor 2 are stopped to avoid excessive fuel consumption.

This embodiment is effective in exhibiting necessary and sufficient power performance when the capacity of the power storage device 3 mounted on the vehicle is originally small or when the amount of charge currently stored in the power storage device 3 is small. do. This is useful in a small vehicle that lacks space for mounting a large-sized, large-capacity power storage device 3 . It is also advantageous for avoiding the increase in weight and cost associated with mounting a large-sized, large-capacity power storage device 3 .

The present invention is not limited to the embodiments detailed above. For example, the vehicle in the above embodiment is a series type hybrid vehicle, and inputting the driving force output from the internal combustion engine 1 to the driving wheels 62 of the vehicle instead of the generator 2 has not been considered.

However, it is also possible to apply the present invention to other types of hybrid vehicles, such as hybrid vehicles in which the driving force output by the internal combustion engine is supplied to the drive wheels for running the vehicle. At this time, between the internal combustion engine and the driving wheels, a state in which the driving force can be transmitted between them, and a state in which the internal combustion engine can rotate/stop independently of the driving wheels without transmitting the driving force between the two. A power transmission mechanism capable of switching between states (such as a clutch capable of switching between disconnection and connection, a transmission mechanism using planetary gears, etc.) is interposed. Then, it determines whether the internal combustion engine is to be operated or stopped according to the required output corresponding to the accelerator opening, etc., and when the internal combustion engine is to be operated, the power transmission mechanism is set to the latter state and the internal combustion engine is motored. Alternatively, fuel is supplied to the cylinders to fire the internal combustion engine, and the power transmission mechanism is placed in the former state so that the driving force output by the internal combustion engine can be supplied to the driving wheels. Needless to say, the power transmission mechanism is placed in the latter state when the operation of the internal combustion engine is to be stopped.

In addition, the specific configuration of each part and the content of processing can be modified in various ways without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to the control of hybrid vehicles.

0... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1... Internal combustion engine 13... Intake passage 132... Throttle valve 15... Brake booster 2... Generator, electric motor for motoring (motor generator for power generation)
3... Power storage device 4... Electric motor for traveling (motor generator for traveling)
62... Drive wheel

Claims (4)

a traveling electric motor capable of supplying a driving force for traveling to the driving wheels;
an internal combustion engine capable of supplying driving force for power generation to a generator that generates electric power to be supplied to the electric motor for traveling, or supplying driving force for traveling to drive wheels;
a brake booster that stores intake negative pressure generated downstream of a throttle valve in an intake passage of an internal combustion engine and utilizes the negative pressure to boost the brake depression force;
A control device for controlling a hybrid vehicle including a motoring electric motor capable of supplying an internal combustion engine with driving force for rotating the internal combustion engine,
When the negative pressure stored in the brake booster falls below the lower limit threshold, motoring is performed to rotate the internal combustion engine using the motoring electric motor, and the negative pressure stored in the brake booster rises above the upper limit threshold, which is higher than the lower limit threshold. The motoring is continued until the negative pressure recovers, and the motoring is terminated on the condition that the negative pressure recovers to the upper limit threshold or more,
A control device for a hybrid vehicle that lowers the upper limit threshold when a predetermined acceleration request condition indicating the driver's intention to accelerate the vehicle is satisfied, compared to when it is not. The accelerator opening degree operated by the driver is larger than a predetermined value, the required output corresponding to the accelerator opening degree and vehicle speed is larger than a predetermined value, or the output, rotation speed, applied current or applied voltage of the traction motor When the amount of increase per unit time of
When the negative pressure stored in the brake booster recovers to the upper limit threshold value or more due to the motoring of the internal combustion engine when the acceleration request condition is satisfied,
Either end the motoring and increase the power supplied from the in-vehicle power storage device to the traction motor, or
Alternatively, if the accelerator opening is greater than or equal to the judgment value, motoring is switched to firing and power is generated by the generator, and if the accelerator opening is less than the judgment value, motoring is terminated and the internal combustion engine rotates. 2. The control device according to claim 1, adapted to stop a traveling electric motor capable of supplying a driving force for traveling to the driving wheels;
an internal combustion engine capable of supplying driving force for power generation to a generator that generates electric power to be supplied to the electric motor for traveling, or supplying driving force for traveling to drive wheels;
a brake booster that stores intake negative pressure generated downstream of a throttle valve in an intake passage of an internal combustion engine and utilizes the negative pressure to boost the brake depression force;
A control device for controlling a hybrid vehicle including a motoring electric motor capable of supplying an internal combustion engine with driving force for rotating the internal combustion engine,
When the negative pressure stored in the brake booster falls below the lower limit threshold, the motoring that rotates the internal combustion engine by the motoring electric motor or the firing that supplies fuel to the internal combustion engine to start and rotate it is performed, and the brake is applied. The motoring or firing continues until the negative pressure stored in the booster recovers to the upper threshold value, which is higher than the lower threshold value. and terminates
If a predetermined acceleration request condition that suggests the driver's intention to accelerate the vehicle is satisfied, the upper limit threshold is lowered compared to the case that it is not, and
The accelerator opening degree operated by the driver is larger than a predetermined value, the required output corresponding to the accelerator opening degree and vehicle speed is larger than a predetermined value, or the output, rotation speed, applied current or applied voltage of the traction motor A control device for a hybrid vehicle that determines that the acceleration request condition is met and lowers the upper limit threshold when the amount of increase in the number per unit time is greater than or equal to a predetermined value. 4. A control system for a hybrid vehicle according to claim 1, wherein said upper limit threshold is set to a value equal to or greater than the minimum negative pressure required to brake a running vehicle.

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