JP7258422B2 - 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, stores the generated power in a power storage device (battery and/or capacitor), and drives a motor. feed the generator. 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 rotate the internal combustion engine. of electricity.

When the amount of electric charge currently stored in the power storage device is below a predetermined amount, or when the required output of the motor generator for traveling is large, the internal combustion engine is started to supply fuel to the cylinders for combustion, The rotational driving force output from the internal combustion engine is used to drive the electric power generation motor generator to generate electric power to charge the power storage device or increase the 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 2016-064735 A

In a hybrid vehicle, even if the internal combustion engine does not burn fuel to generate rotational driving force, the vehicle can be driven by the rotational driving force output from the motor generator for traveling. Therefore, even during operation of the vehicle, the frequency of stopping the operation of the internal combustion engine is high, and the stopping of the internal combustion engine may continue for a relatively long time.

While the internal combustion engine is stopped, it is customary to open the throttle valve on the intake passage to a certain degree or more in preparation for restarting later. In addition, when the rotation of the internal combustion engine stops in a valve overlap state in which both the intake valve and the exhaust valve of one of the cylinders of the internal combustion engine are open, the running dynamic pressure causes the intake port of the intake passage to Air flows through the cylinder toward the catalyst for purifying exhaust gas in the exhaust passage. As a result, the cylinders and the catalyst for purifying the exhaust are cooled excessively, resulting in a decrease in temperature, which deteriorates the startability of the internal combustion engine, reduces the combustion efficiency immediately after starting, and increases the amount of harmful substances contained in the exhaust. There is a concern that there will be inconveniences such as

SUMMARY OF THE INVENTION The present invention has been made for the first time by focusing on the above problems, and an intended object of the present invention is to suppress excessive cooling of a cylinder and/or a catalyst while an internal combustion engine is stopped in a hybrid 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 hybrid vehicle equipped with an internal combustion engine capable of supplying driving force for is operated to fully close the EGR valve on the EGR passage connecting the internal combustion engine , and the gap between the intake port of the intake passage of the internal combustion engine and the catalyst for purifying the exhaust gas of the exhaust passage is closed. A control device for a hybrid vehicle that does not perform such an operation if the temperature is higher than or equal to or higher than a predetermined value or that does not perform such an operation if the temperature of the catalyst for purifying exhaust gas is higher than a predetermined value. .

According to the present invention, it is possible to suppress excessive cooling of the cylinders and/or the catalyst while the internal combustion engine is stopped in the hybrid vehicle.

1 is a diagram showing an overview of a series hybrid vehicle and a control device according to an embodiment of the present invention; FIG. FIG. 4 is a diagram showing the classification of the required output in the control performed by the control device of the embodiment; The figure which shows the schematic structure of the internal combustion engine mounted in the hybrid vehicle of the same embodiment. FIG. 4 is a timing chart showing the stroke of each cylinder of a three-cylinder internal combustion engine and the crank angle at which valve overlap occurs.

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 driving motor generator 4 and the drive wheels 62 . 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 in which the electric charge is stored, 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 . In addition, the electric power generation motor generator 2 also functions as an electric motor that generates rotational driving force by itself 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 .

However, if electric charge is already stored up to the capacity of the electric 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, a fuel cut can be executed to temporarily stop the supply of fuel to the cylinders 11 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 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 .

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 engine controller 01 that controls the internal combustion engine 1, a generator controller 02 that controls the power generation motor generator 2 and the generator inverter 21, a battery controller 03 that controls the power storage device 3, and a driving motor. A driver controller 04 and the like for controlling the generator 4 and the driver inverter 41 are connected so as to be able to communicate with each other via an electric communication line such as a CAN (Controller Area Network).

The ECU 0 senses the accelerator opening degree operated by the driver, that is, the amount of depression of the accelerator pedal, the shift position, that is, the position of the shift lever or selector lever, the ON/OFF state of the switch, and the current vehicle speed. , the road gradient, the amount of electricity stored in the electricity storage device 3, the power generated by the motor generator 2 for power generation, etc., the rotational driving force output by the motor generator 4 for traveling, the rotational driving force output by the internal combustion engine 1, The magnitude of electric power generated by the motor generator 2 is controlled to increase or decrease.

If the power storage device 3 currently stores a sufficient amount of electric charge and the required output of the running 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 not operated. On the other hand, if the amount of electric charge currently stored in the power storage device 3 is below a predetermined amount, or if the required output of the motor-generator 4 for traveling is large, the internal combustion engine 1 is started and the cylinders 11 The fuel is supplied to and combusted, and the rotational driving force output from the internal combustion engine 1 is used to drive the power generation amount motor generator 2, and the power is generated to charge the power storage device 3 or to be supplied to the running motor generator 4. increase the power to run.

FIG. 2 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. In principle, the required output increases as the accelerator opening increases, and increases as the vehicle speed increases. In FIG. 2, 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.

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 11 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. When about to start, the power generation motor generator 2 performs motoring for starting the internal combustion engine 1 . Motoring for starting the internal combustion engine 1 continues until the internal combustion engine 1 burns fuel and can rotate independently. More specifically, the rotational speed of the crankshaft of the internal combustion engine 1 being sensed rises above the minimum value required for starting, and the crankshaft of the internal combustion engine 1 rotates more than a predetermined number of times from the start of motoring or reaches a predetermined speed. Motoring is terminated when the rotation is equal to or more than the angle. After the start of the internal combustion engine 1 is completed and the motoring of the internal combustion engine 1 is finished, the electric power supply to the power generation motor generator 2 is reduced to zero.

The condition that the crankshaft has rotated a predetermined number of times or more or a predetermined angle or more may be replaced with the completion of cylinder discrimination for obtaining the current stroke or piston position of each cylinder 11 of the internal combustion engine 1 . Naturally, the current stroke of each cylinder 11 needs to be known in order to inject fuel at an appropriate timing according to the stroke of each cylinder 11 and to ignite and burn the fuel at an appropriate timing. Cylinder discrimination is performed using a crank angle sensor that emits a pulse signal each time the crankshaft of the internal combustion engine 1 rotates by a predetermined angle, and a cam angle sensor that emits a pulse signal each time the intake camshaft or exhaust camshaft rotates by a predetermined angle. . Since the method of discriminating cylinders is well known, the explanation thereof is omitted here.

FIG. 3 shows an outline of an internal combustion engine 1 mounted on a hybrid vehicle. The internal combustion engine 1 is, for example, a spark ignition four-stroke engine, and includes a plurality of cylinders 11 (one of which is shown in FIG. 1). In this embodiment, a three-cylinder engine having three cylinders 11 is assumed as the internal combustion engine 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 input interface of the engine controller 01 forming a part of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a rotation angle of the crankshaft of the internal combustion engine 1, and a crank angle that detects the engine speed. Output from a sensor that detects the crank angle signal b output from a sensor (engine rotation sensor), the depression amount of the accelerator pedal, or the opening of the throttle valve 132 as the accelerator opening (engine output requested by the driver, requested load factor). A brake depression amount signal d output from a sensor that detects the depression amount of the brake pedal or a master cylinder pressure that is the pressure of hydraulic fluid discharged from the master cylinder, and an intake passage 13 Intake air temperature/intake pressure signal e output from a temperature/pressure sensor that detects the intake air temperature and pressure in the surge tank 133 (in particular, the surge tank 133) Output from a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine 1 A cooling water temperature signal f, a cam angle signal g output from a cam angle sensor at multiple cam angles of an intake camshaft or an exhaust camshaft, an atmospheric pressure signal h output from an atmospheric pressure sensor for detecting atmospheric pressure, etc. are input. be done.

From the output interface of the engine controller 01 , an ignition signal i for the igniter of the spark plug 112 , a fuel injection signal j for the injector 111 , an opening operation signal k for the throttle valve 132 , and an opening signal k for the EGR valve 123 . It outputs a degree operation signal l and the like.

The processor of the engine controller 01 interprets and executes a program stored in memory in advance, calculates operating parameters, and controls the operation of the internal combustion engine 1 . The engine controller 01 acquires various types of information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine 1 via an input interface, acquires the engine speed, and controls the cylinders 11. Estimate the amount of air inhaled. Then, various types of operation such as the required fuel injection amount corresponding to the intake air amount, fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR gas amount), etc. Determine parameters. The engine controller 01 applies various control signals i, j, k, l corresponding to operating parameters through an output interface.

When the operation of the internal combustion engine 1 is stopped, a valve overlap state may occur in which both the intake valve and the exhaust valve of one of the cylinders 11 are open. In particular, in the three-cylinder engine 1, as shown in FIG. 4, the timing (or crank angle) T at which one cylinder 11 approaches the compression stroke from the intake stroke, in other words, the piston of the same cylinder 11 is at the intake bottom dead center. At the timing when it starts to rise toward compression top dead center after reaching , it sometimes stops due to increased rotational resistance.
In this case, any one of the other cylinders 11 is about to enter the intake stroke from the exhaust stroke, and both the intake valve and the exhaust valve of that cylinder 11 are opened.

Even while the internal combustion engine 1 is stopped in this state, the vehicle is running. Therefore, due to the running dynamic pressure, running wind, that is, air blows from the intake port into the intake passage 13 and blows through from the intake passage 13 side to the exhaust passage 14 side via the cylinder 11 concerned. As a result, the combustion chamber of the cylinder 11 and the catalyst 141 for purifying the exhaust gas are excessively cooled to lower the temperature. The temperature drop in the combustion chamber of the cylinder 11, together with the temperature difference between the combustion chambers of the other cylinders 11, causes a decrease in the combustion efficiency of the air-fuel mixture, a delay in starting the internal combustion engine, deterioration of fuel efficiency, and the like. In addition, the temperature drop of the catalyst 141 lowers the purification efficiency of the harmful substances HC, CO and NO _x by the catalyst 141, leading to an increase in the amount of harmful substances discharged.

Therefore, (the engine controller 01 of) the ECU 0 of the present embodiment controls the air cleaner at the intake port of the intake passage 13 of the internal combustion engine 1 when the operation of the internal combustion engine 1 is stopped and the vehicle is caused to run by the motor generator 4 for running. 131 and the catalyst 141 of the exhaust passage 14 are closed. For example, while the internal combustion engine 1 is stopped, the throttle valve 132 on the intake passage 13 and the EGR valve 123 on the external EGR passage 121 connecting the intake passage 13 and the exhaust passage 14 are fully closed. As a result, even if both the intake valve and the exhaust valve of any one of the cylinders 11 are open, the intake passage 13 and the exhaust passage 14 are not consistently communicated with each other and are isolated from each other. It is possible to prevent the air from flowing toward the catalyst 141 of 14.

Alternatively, when stopping the operation of the internal combustion engine 1, (the generator controller 02 of) the ECU 0 controls the power generation motor generator so that the internal combustion engine 1 does not stop at the timing T when any of the cylinders 1 is in the valve overlap state. It is also conceivable to control the rotation of 2. By doing so, the air cleaner 131 in the intake passage 13 and the catalyst 141 in the exhaust passage 14 can be closed by the intake and exhaust valves of the cylinder 11 .

If a shutter valve other than the throttle valve 132 is provided on the intake passage 13 or the exhaust passage 14 of the internal combustion engine 1, (the engine controller 01 of) the ECU 0 performs an operation to fully close the shutter valve, Thus, the air may be prevented from flowing from the air cleaner 131 in the intake passage 13 toward the catalyst 141 in the exhaust passage 14 .

The operations described above are not always executed when the operation of the internal combustion engine 1 is stopped. If the current temperature of the cooling water of the internal combustion engine 1 or the temperature of the catalyst 141 is higher than a predetermined value, it is preferable not to perform the above operations and to avoid power consumption associated with the operations.

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 A hybrid vehicle comprising an engine 1 and a motoring electric motor 2 capable of supplying a driving force for rotating the internal combustion engine 1 to the internal combustion engine 1 is controlled by stopping the internal combustion engine 1 to start the vehicle. A control device 0 for a hybrid vehicle is configured to close the space between the intake port 131 of the intake passage 13 of the internal combustion engine 1 and the exhaust purification catalyst 141 of the exhaust passage 14 while the vehicle is running.

According to the present embodiment, excessive cooling of the cylinders 11 and the catalyst 141 while the operation of the internal combustion engine 1 is stopped is suppressed. As a result, it is possible to avoid problems such as a decrease in fuel combustion efficiency in the internal combustion engine 1, start delay or start failure of the internal combustion engine, and an increase in emissions of harmful substances.

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

However, it is of course possible to apply the present invention to a hybrid vehicle in which the driving force output by the internal combustion engine can be supplied to the drive wheels for running the vehicle. At this time, between the internal combustion engine and the drive wheels, there are two states: a state in which driving force can be transmitted between them, and a state in which the internal combustion engine can rotate independently of the driving wheels without transmitting driving force between them. A power transmission mechanism (such as a clutch capable of switching between connection and disconnection, a transmission mechanism using planetary gears, etc.) is provided. Then, it determines whether the internal combustion engine is to be operated or stopped according to the required output corresponding to the accelerator opening and the like, and when the internal combustion engine is to be operated, the power transmission mechanism is set to the latter state and motoring of the internal combustion engine is started. Then, fuel is supplied to the cylinders to start 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 drive 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)
REFERENCE SIGNS LIST 1 internal combustion engine 12 exhaust gas recirculation (EGR) device 121 external EGR passage 123 EGR valve 13 intake passage 131 intake port (air cleaner)
DESCRIPTION OF SYMBOLS 132... Throttle valve 14... Exhaust passage 141... Catalyst for purifying exhaust gas 2... Generator, electric motor for motoring (motor generator for power generation)
4 . . . Electric motor for traveling (motor generator for traveling)
3... Power storage device 62... Drive wheel

Claims (1)

a traveling electric motor capable of supplying a driving force for traveling to the driving wheels;
It controls a hybrid vehicle equipped with an internal combustion engine that can supply driving force for power generation to a generator that generates electric power to be supplied to a traction motor, or can supply driving force for running to drive wheels. There is
When the vehicle is running with the internal combustion engine stopped , the throttle valve on the intake passage and the EGR valve on the EGR passage that connects the intake passage and the exhaust passage are fully closed by performing an operation to fully close the intake of the intake passage of the internal combustion engine. The gap between the port and the exhaust purification catalyst in the exhaust passage is closed, but if the cooling water temperature of the internal combustion engine is higher than a predetermined value, such operation is not performed, or the temperature of the exhaust purification catalyst is a high temperature equal to or higher than a predetermined value, the control device for a hybrid vehicle does not perform such an operation .

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