JP2023028185A - Hybrid vehicle control method and control device - Google Patents

Abstract

To curb consumption of oil due to negative pressure when motoring of an internal combustion engine 2 is performed with a motor generator 1 for power generation.SOLUTION: An internal combustion engine 2 comprises an electrically assisted turbocharger 12 which functions as an electric compressor. When motoring of the internal combustion engine 2 is performed for reducing SOC of a battery 5, a motor generator section 12c of the turbocharger 12 is driven so as to increase pressure of intake air supplied to a combustion chamber 10 and thereby preventing transfer of oil from a crank case 20 to the combustion chamber 10 during the motoring. Although a reduction in a pump loss causes electricity consumption of the motor generator 1 for power generation to be reduced, total electricity consumption including the electricity consumption of the motor generator section 12c can be increased.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control method and control apparatus for a hybrid vehicle in which motoring of an internal combustion engine is sometimes performed by power running of a motor generator.

In hybrid vehicles equipped with an internal combustion engine and a motor generator, such as series hybrid vehicles, series-parallel hybrid vehicles, or parallel hybrid vehicles, motoring of the internal combustion engine may be performed by power running of the motor generator.

For example, in Patent Document 1, when regenerative braking is performed by a motor-generator for running in a situation where there is no charge margin in the battery, the internal combustion engine is motored by another motor-generator connected to the internal combustion engine, and regenerative braking is performed. A technique is disclosed in which excess electric power generated by braking is consumed by this motoring.

Japanese Patent Application Laid-Open No. 2010-018212

When the internal combustion engine is motored as described above, the inside of the cylinder becomes negative pressure, especially during the downward stroke of the piston, and the oil in the crankcase tends to seep out to the combustion chamber side. As a result, there is a problem that oil consumption increases and HC contained in the oil is discharged to the outside.

The control of the hybrid vehicle according to the present invention is performed by providing an electric compressor in the intake system of the internal combustion engine in a hybrid vehicle in which motoring of the internal combustion engine is sometimes performed by power running of the motor generator, and operating the electric compressor during motoring. to increase the pressure of the intake air supplied to the combustion chamber of the internal combustion engine.

According to this invention, the operation of the electric compressor increases the intake pressure during motoring, thereby suppressing the development of negative pressure in the cylinder. As a result, the amount of oil seeping into the combustion chamber is reduced.

FIG. 2 is a configuration explanatory diagram of a series hybrid vehicle; 1 is an explanatory diagram of the configuration of an internal combustion engine according to an embodiment; FIG. FIG. 4 is an explanatory diagram showing power consumption during motoring in an embodiment in comparison with a reference example;

FIG. 1 schematically shows the configuration of a series hybrid vehicle as an example of a hybrid vehicle to which the present invention is applied. The series hybrid vehicle includes a motor generator 1 for power generation that mainly operates as a power generator, an internal combustion engine 2 that is used as an internal combustion engine for power generation that drives the motor generator 1 for power generation according to electric power demand, and an internal combustion engine 2 that mainly operates as a motor. It is composed of a traveling motor generator 4 that drives the drive wheels 3 as a driving force, and a battery 5 that temporarily stores the generated electric power. Electric power obtained by the internal combustion engine 2 driving the motor generator 1 is stored in the battery 5 via an inverter device (not shown). The driving motor generator 4 is driven and controlled using the electric power of the battery 5 . Electric power generated during regeneration by the running motor generator 4 is stored in the battery 5 via an inverter device (not shown).

A controller 6 controls the operations of the motor generators 1 and 4 , the charging and discharging of the battery 5 , and the operation of the internal combustion engine 2 . The controller 6 includes a plurality of controllers connected so as to communicate with each other, such as a motor controller 7 that controls the motor generators 1 and 4, an engine controller 8 that controls the internal combustion engine 2, and a battery controller 9 that manages the battery 5. It is Information such as the degree of opening of an accelerator pedal (not shown) and vehicle speed is input to the controller 6 . The battery controller 9 also obtains the SOC of the battery 5 based on the voltage/current of the battery 5 . When the SOC drops to a predetermined lower limit level, the internal combustion engine 2 is started via the engine controller 8 to generate power. That is, the internal combustion engine 2 that drives the power generation motor generator 1 is started/stopped via the engine controller 8 based on the electric power demand according to the SOC of the battery 5, the opening degree of the accelerator pedal, and the like.

FIG. 2 shows the system configuration of the internal combustion engine 2. As shown in FIG. The internal combustion engine 2 is a four-stroke cycle spark ignition internal combustion engine equipped with a turbocharger 12. A pair of intake valves 14 and a pair of exhaust valves 15 are arranged on the ceiling wall surface of each cylinder 13. , and an ignition plug 16 is arranged in a central portion surrounded by the intake valve 14 and the exhaust valve 15 . A fuel injection valve 17 that supplies fuel into the cylinder 13 is provided below the intake valve 14 . The engine controller 8 controls the ignition timing of the ignition plug 16 and the injection timing and injection amount of fuel by the fuel injection valve 17 . The combustion chamber 10 is separated from the space in the crankcase 20 by a piston 11 that slides up and down in the cylinder 13 .

Here, as the turbocharger 12, an electrically assisted turbocharger having a motor generator section 12c coaxially with the turbine 12b and the compressor 12a is used. In this electrically assisted turbocharger 12, even when the combustion operation of the internal combustion engine 2 is stopped, it is possible to rotate the rotor by the power running of the motor generator section 12c and pump the intake air. That is, it functions as a kind of electric compressor. Further, during the combustion operation of the internal combustion engine 2, the motor-generator section 12c is regeneratively controlled so as to absorb excess exhaust energy, which can be recovered as electric power. The motor generator section 12 c is controlled by the engine controller 8 . Electric power necessary for the motor generator section 12c is supplied from the battery 5 for running the vehicle via an inverter circuit (not shown), and the electric power obtained by regeneration is similarly stored in the battery 5 for running the vehicle.

Also, the intake valve 14 and the exhaust valve 15 are provided with variable valve mechanisms 18 and 19 capable of changing their opening timing and closing timing. Although the variable valve mechanisms 18 and 19 may be of any type, for example, a mechanism that delays the phase of the camshaft with respect to the phase of the crankshaft can be used. Furthermore, the configuration may be such that the valve lift amount can be changed in addition to the opening timing and the closing timing.

The intake passage 21 has an intake collector 21a, and an electronically controlled throttle valve 22 whose opening is controlled by a control signal from the engine controller 8 is provided upstream of the intake collector 21a. A compressor 12a of the turbocharger 12 is positioned upstream of the throttle valve 22, and an air flow meter 24 and an air cleaner 25 for detecting the amount of intake air are disposed upstream of the compressor 12a. A water-cooled intercooler 26, for example, is provided between the compressor 12a and the throttle valve 22 to cool the high temperature and high pressure intake air. A recirculation valve 27 is provided to communicate the discharge side and the suction side of the compressor 12a.

A turbine 12b of the turbocharger 12 is positioned in the exhaust passage 30, and a pre-catalyst device 31 and a main catalyst device 32 for purifying exhaust gas are disposed downstream thereof. The pre-catalyst device 31 is arranged at the outlet of the turbine 12b, and the main catalytic device 32 is arranged under the floor of the vehicle. An air-fuel ratio sensor 33 that detects the air-fuel ratio is arranged upstream of the turbine 12b in the exhaust passage 30 . Turbine 12b includes a wastegate valve 34 that bypasses a portion of the exhaust in response to boost pressure to control boost pressure. The wastegate valve 34 is, for example, of an electric type whose opening is controlled by the engine controller 8 .

As an exhaust gas recirculation passage for recirculating part of the exhaust gas from the exhaust passage 30 to the intake passage 21, a low-pressure exhaust gas recirculation passage 35 for recirculating the exhaust gas from the downstream side of the turbine 12b to a position upstream of the compressor 12a and the upstream side of the turbine 12b. A high-pressure exhaust gas recirculation passage 36 for recirculating the exhaust gas to a position downstream of the compressor 12a, for example, the intake collector 21a. The low-pressure exhaust gas recirculation passage 35 is provided with, for example, a water-cooled EGR gas cooler 37 and a low-pressure EGR valve 38 . A high pressure EGR valve 39 is provided in the high pressure exhaust gas recirculation passage 36 . Basically, the exhaust gas is recirculated through the low-pressure exhaust gas recirculation passage 35 in the supercharging region, and the exhaust gas is recirculated through the high-pressure exhaust gas recirculation passage 36 in the non-supercharging region.

In addition to the air flow meter 24 and the air-fuel ratio sensor 33, the engine controller 8 includes a crank angle sensor 41 for detecting the engine speed, a water temperature sensor 42 for detecting the cooling water temperature, and a supercharging sensor for detecting the supercharging pressure. Detection signals from sensors such as the pressure sensor 43 are input. Based on these detection signals and requests from other controllers 7 and 9, the engine controller 8 optimally controls the fuel injection amount, injection timing, ignition timing, opening of the throttle valve 22, supercharging pressure, etc. there is

The internal combustion engine 2 is basically started when the SOC of the battery 5 drops to a predetermined lower limit SOC value, and is stopped when the SOC recovers to a predetermined level. That is, the internal combustion engine 2 drives the power generation motor generator 1 to generate power. The generated electric power is consumed by the traveling motor generator 4 and the surplus electric power is stored in the battery 5 . Further, when the vehicle is decelerating or descending a slope, the motor generator 4 for traveling is regeneratively controlled, and the obtained electric power is collected in the battery 5 .

On the other hand, the internal combustion engine 2 connected to the power generation motor generator 1 may be motored by the power running of the power generation motor generator 1 depending on the conditions. For example, when the SOC of the battery 5 reaches a predetermined upper limit SOC value during regenerative control of the motor generator 4 for traveling, the internal combustion engine using the motor generator 1 for power generation is used to avoid deterioration of the battery 5 due to overcharging. 2 motoring is performed and regenerative power is consumed. Note that power consumption by such motoring can be executed, for example, during running downhill while regeneration is actually being performed, or the power can be reduced before reaching the downhill so that the SOC of the battery 5 can be lowered in advance by predicting the downhill. may be executed at

When the internal combustion engine 2 is motored from the outside in this way, as described above, the inside of the cylinder 13 becomes negative pressure especially during the downward stroke of the piston 11, and the oil in the crankcase 20 seeps into the combustion chamber 10 side. easier. As a result, there is a problem that oil consumption increases and HC contained in the oil is discharged to the outside. In order to suppress the development of such negative pressure, in this embodiment, when the internal combustion engine 2 is motored by the motor generator 1 for power generation, the motor generator section 12c of the turbocharger 12 is turned on in parallel with this. It is rotationally driven, and the intake air is pressure-fed by the compressor 12a. As a result, the pressure in the intake collector 21a increases, which in turn increases the pressure in the combustion chamber 10 during motoring. Therefore, less oil leaks from the crankcase 20 to the combustion chamber 10 side.

In a preferred embodiment, the turbocharger 12 is driven to such an extent that the pressure inside the combustion chamber 10 is positive even during the downward stroke of the piston 11 . By maintaining the positive pressure in this manner, the movement of oil from the crankcase 20 to the combustion chamber 10 side due to the pressure difference is reliably suppressed. However, even if the pressure in the combustion chamber 10 becomes negative during the downward stroke of the piston 11, the pressure in the crankcase 20 and the pressure in the combustion chamber 10 are increased by pressurizing the intake air by driving the turbocharger 12. Since the pressure difference is reduced, the effect of reducing the movement of oil to the combustion chamber 10 side is obtained.

On the other hand, powering the motor generator section 12c of the turbocharger 12 during motoring of the internal combustion engine 2 is advantageous in terms of power consumption. That is, the power consumption of the motor-generator section 12c is added to the power consumption of the motor-generator 1 for power generation, and the consumption of regenerated power on a downhill road or the like or the decrease in the SOC of the battery 5 is accelerated.

More strictly speaking, the turbocharger 12 performs the supercharging operation to reduce the pump loss of the internal combustion engine 2 , thereby reducing the power consumption of the motor generator 1 required for motoring the internal combustion engine 2 . However, the addition of the power consumption of the motor generator section 12c makes the total power consumption relatively large.

FIG. 3 is an explanatory diagram illustrating the power consumption of (a) a comparative example that does not use the electric assist turbocharger 12 and (b) an embodiment that adds a supercharging operation using the electric assist turbocharger 12. .

In the case of the comparative example (a), where W ₀ is the required power consumption and W ₁ is the power consumption of the motor generator 1 during motoring, there is a relationship of W ₀ =W ₁ . At this time, the pressure P ₁ in the cylinder 13 becomes "P ₁ <0", that is, a negative pressure. The power consumption W ₁ and the pressure P ₁ are correlated with each other, and the pressure P ₁ decreases (negative pressure develops) as the power consumption W ₁ is increased by controlling the opening of the throttle valve 22 or the like. In other words, if you try to obtain a large power consumption _W1 , the oil consumption will increase accordingly.

In the case _of the _embodiment ( _b ), W There is a relationship of ₀ = _W2 + _W3 . Therefore, the relationship W ₁ >W ₂ is obtained. That is, for the same required power consumption _W0 , the power consumption _W2 of the power generation motor generator 1 is smaller than the power consumption _W1 in the comparative example (a) by the power consumption _W3 of the motor generator section 12c. . Then, the pressure _P2 in the cylinder 13 at this time becomes higher than the pressure _P1 in the case of the comparative example (a). This pressure _P2 also correlates with the power consumption _W2 required for motoring. That is, the power consumption _W2 becomes smaller than _W1 when the pressure _P2 becomes higher than _P1 .

Thus, in the above embodiment, if the same required power consumption _W0 is consumed, the pressure _P2 in the cylinder 13 can be increased by driving the turbocharger 12 with the motor generator section 12c. As a result, seepage of oil from the crankcase 20 is suppressed.

Also, if the pressure in the cylinder 13 is allowed to be approximately the same as in the comparative example, the total power consumption (W ₂ +W ₃ ) will be greater than the power consumption W ₁ in the comparative example. This means, for example, that the motoring time required to lower the SOC of the battery 5 to a certain level is shortened, and as a result, the battery moves from the crankcase 20 to the combustion chamber 10 side along with the motoring. less oil to run.

The pump loss during motoring (that is, the power consumption W ₂ required for motoring) depends on, for example, the opening of the throttle valve 22, the opening/closing characteristics of the intake valve 14 and the exhaust valve 15 by the variable valve mechanisms 18 and 19 (opening/closing timing, lift amount, etc.), the degree of opening of the high-pressure EGR valve 39 in the high-pressure exhaust gas recirculation passage 36, and the like. In a preferred embodiment, controlling at least one of these factors sets pump losses appropriately. By combining the control of these elements with the control of the motor generator section 12c of the turbocharger 12, the pressure in the combustion chamber 10 can be appropriately controlled, and the balance between the pressure in the cylinder 13 and the total power consumption can be optimized. It is possible to

Note that while the internal combustion engine 2 is in combustion operation, the electrically assisted turbocharger 12 can be used in a general manner. That is, at the start of supercharging or when the exhaust energy is insufficient, the supercharging response can be enhanced by the power running of the motor generator section 12c. When the exhaust energy is excessive, the exhaust energy can be recovered by the regeneration control of the motor generator section 12c.

An embodiment in which the present invention is applied to a series hybrid vehicle has been described above, but the present invention is not limited to the above embodiment, and various modifications are possible. For example, the present invention can be applied to hybrid vehicles other than the series hybrid type, and can be widely applied to hybrid vehicles in which motoring of an internal combustion engine can be performed by power running of a motor generator regardless of the type. Further, in the above embodiment, an electric assist turbocharger is used as the electric compressor, but any type of electric compressor may be used, and a relatively low-pressure so-called blower may be used. It is not always necessary to use a supercharger for supercharging during combustion operation, and it is also possible to have a configuration provided with an electric compressor for adjusting pressure during motoring.

DESCRIPTION OF SYMBOLS 1... Motor generator for electric power generation 2... Internal combustion engine 4... Motor generator for traveling 5... Battery 6... Controller 8... Engine controller 10... Combustion chamber 12... Turbocharger 12a... Compressor 12b... Turbine 12c... Motor generator part 18, 19... Variable Valve mechanism 22... Throttle valve 39... High pressure EGR valve

Claims (7)

In a hybrid vehicle in which motoring of an internal combustion engine may be performed by power running of a motor generator,
An electric compressor is provided in the intake system of the internal combustion engine,
During motoring, the electric compressor is operated to increase the pressure of the intake air supplied to the combustion chamber of the internal combustion engine.
A control method for a hybrid vehicle. As the electric compressor, an electric assist turbocharger having a motor generator unit coaxial with the turbine and the compressor is used.
A control method for a hybrid vehicle according to claim 1. In order to consume surplus power from the running battery that exchanges power with both the motor generator and the electric compressor, motoring is performed by the motor generator and intake air is pressurized by the electric compressor.
A control method for a hybrid vehicle according to claim 1 or 2. operating the electric compressor so that the combustion chamber of the internal combustion engine has a positive pressure;
The hybrid vehicle control method according to any one of claims 1 to 3. At least one of opening/closing characteristics of an intake valve or an exhaust valve, an opening degree of a throttle valve in an intake passage, and an opening degree of an exhaust recirculation control valve in an exhaust recirculation passage that guides EGR gas from an exhaust passage upstream of the turbine to an intake passage downstream of the compressor. Combining one control and the control of the electrically assisted turbocharger to control the pressure in the combustion chamber;
A control method for a hybrid vehicle according to claim 2. The motor-generator is a motor-generator for power generation driven by an internal combustion engine, and the series hybrid vehicle is driven by another motor-generator for running.
The hybrid vehicle control method according to any one of claims 1 to 5. a motor generator used at least for power generation;
an internal combustion engine that drives the motor generator for power generation and is capable of motoring by powering the motor generator;
an electric compressor provided in an intake system of an internal combustion engine;
a controller that operates the electric compressor to increase the pressure of intake air supplied to a combustion chamber of the internal combustion engine when the internal combustion engine is motored;
A hybrid vehicle control device comprising:

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