Hybrid vehicle control method and control device

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

[Technical Field]

[0001] The present invention relates to a control method and a control device for a hybrid vehicle in which an internal combustion engine is motored by powering a motor generator. [Background technology]

[0002] In hybrid vehicles equipped with an internal combustion engine and a motor generator, such as a series hybrid vehicle, a series-parallel hybrid vehicle, or a parallel hybrid vehicle, the internal combustion engine may be motored by powering the motor generator.

[0003] For example, Patent Document 1 discloses a technology in which, when regenerative braking is performed by a driving motor generator under circumstances in which the battery does not have a sufficient charge, the internal combustion engine is motored by another motor generator connected to the internal combustion engine, and the excess power generated by the regenerative braking is consumed by this motoring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-018212 Summary of the Invention [Problem to be solved by the invention]

[0005] When an internal combustion engine is motored as described above, negative pressure is created inside the cylinder, especially during the piston's downward stroke, making it easier for oil in the crankcase to seep into the combustion chamber. This results in increased oil consumption and the release of HC contained in the oil to the outside. [Means for solving the problem]

[0006] The control of the hybrid vehicle according to the present invention comprises: A series hybrid vehicle equipped with a power generating motor generator, an internal combustion engine that drives the power generating motor generator to generate electricity, and a traction motor generator that drives the drive wheels using the generated electricity.In hybrid vehicles, An electric compressor is provided in the intake system of the internal combustion engine, When consumption of surplus power is required, the internal combustion engine is motored by powering the power generating motor generator, which consumes power; this When motoring the above Turn on the electric compressor While consuming electricity It increases the pressure of the intake air supplied to the combustion chamber of an internal combustion engine. [Effects of the Invention]

[0007] According to this invention, When consumption of surplus electricity is required, the electric compressor operates in conjunction with the motoring of the internal combustion engine by the power generation motor generator, thereby enabling effective power consumption. The operation of the electric compressor increases the intake pressure during motoring, suppressing the development of negative pressure inside the cylinder. Problems when motoring Less oil seeps into the combustion chamber. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of the configuration of a series hybrid vehicle. [Figure 2] 1 is a diagram illustrating the configuration of an internal combustion engine according to an embodiment; [Figure 3] FIG. 10 is an explanatory diagram showing the power consumption during motoring of the embodiment in comparison with a reference example. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 shows a schematic configuration of a series hybrid vehicle as an example of a hybrid vehicle to which the present invention can be applied. The series hybrid vehicle is configured to include a power-generating motor-generator 1 that operates primarily as a generator, an internal combustion engine 2 used as a power-generating internal combustion engine that drives the power-generating motor-generator 1 in response to power demands, a traction motor-generator 4 that operates primarily as a motor to drive drive wheels 3, and a battery 5 that temporarily stores the generated power. The power obtained by the internal combustion engine 2 driving the power-generating motor-generator 1 is stored in the battery 5 via an inverter device (not shown). The traction motor-generator 4 is driven and controlled using the power from the battery 5. The power generated by the traction motor-generator 4 during regeneration is stored in the battery 5 via an inverter device (not shown).

[0010] The operation of the motor generators 1 and 4, the charging and discharging of the battery 5, and the operation of the internal combustion engine 2 are controlled by a controller 6. The controller 6 is composed of multiple controllers connected to each other so that they can 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. Information such as the accelerator pedal position and vehicle speed (not shown) is input to the controller 6. The battery controller 9 also calculates the SOC of the battery 5 based on the voltage and 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 electricity. That is, the internal combustion engine 2 that drives the power-generating motor generator 1 is started and stopped via the engine controller 8 based on the power requirement corresponding to the SOC of the battery 5, the accelerator pedal position, etc.

[0011] 2 shows the system configuration of an internal combustion engine 2. This internal combustion engine 2 is a four-stroke, 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 of each cylinder 13, and a spark plug 16 is arranged in the center surrounded by these intake valves 14 and exhaust valves 15. A fuel injection valve 17 that supplies fuel into the cylinder 13 is provided below the intake valve 14. The ignition timing of the spark plug 16 and the injection timing and injection amount of fuel by the fuel injection valve 17 are controlled by an engine controller 8. The combustion chamber 10 is separated from the space inside a crankcase 20 by a piston 11 that slides up and down inside the cylinder 13.

[0012] Here, an electrically assisted turbocharger having a motor-generator unit 12c coaxially arranged with a turbine 12b and a compressor 12a is used as the turbocharger 12. In this electrically assisted turbocharger 12, the rotor can be rotated by the power running of the motor-generator unit 12c to compress and feed intake air even when the combustion operation of the internal combustion engine 2 is stopped. In other words, it functions as a kind of electric compressor. Furthermore, while the internal combustion engine 2 is operating in combustion mode, the motor-generator unit 12c can be controlled to regenerate and absorb excess exhaust energy, recovering it as electric power. The motor-generator unit 12c is controlled by the engine controller 8. The electric power required for the motor-generator unit 12c is supplied from the vehicle battery 5 via an inverter circuit (not shown), and the regenerated electric power is similarly stored in the vehicle battery 5.

[0013] The intake valve 14 and the exhaust valve 15 are equipped with variable valve mechanisms 18, 19 that can change the opening and closing timings of the valves, respectively. These variable valve mechanisms 18, 19 may be of any type, for example, a mechanism that retards the phase of the camshaft relative to the phase of the crankshaft. Furthermore, the variable valve mechanisms 18, 19 may be configured to change the valve lift in addition to the opening and closing timings.

[0014] The intake passage 21 has an intake collector 21a, and upstream of this intake collector 21a is provided an electronically controlled throttle valve 22 whose opening is controlled by a control signal from the engine controller 8. The compressor 12a of the turbocharger 12 is located upstream of the throttle valve 22, and an air flow meter 24 that detects the amount of intake air and an air cleaner 25 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, high-pressure intake air. A recirculation valve 27 is also provided to communicate the discharge side and intake side of the compressor 12a.

[0015] The turbine 12b of the turbocharger 12 is located in the exhaust passage 30, and a pre-catalytic device 31 and a main catalytic device 32 for purifying exhaust gas are disposed downstream of the turbine 12b. The pre-catalytic device 31 is disposed at the outlet of the turbine 12b, and the main catalytic device 32 is disposed under the floor of the vehicle. An air-fuel ratio sensor 33 for detecting the air-fuel ratio is disposed upstream of the turbine 12b in the exhaust passage 30. The turbine 12b is equipped with a wastegate valve 34 that bypasses part of the exhaust gas in accordance with the boost pressure in order to control the boost pressure. The wastegate valve 34 is, for example, an electrically operated valve whose opening is controlled by the engine controller 8.

[0016] The engine also includes exhaust gas recirculation passages that recirculate a portion of the exhaust gas from the exhaust passage 30 to the intake passage 21. These passages include a low-pressure exhaust gas recirculation passage 35 that recirculates the exhaust gas from the downstream side of the turbine 12b to a position upstream of the compressor 12a, and a high-pressure exhaust gas recirculation passage 36 that recirculates the exhaust gas from the upstream side of the turbine 12b to a position downstream of the compressor 12a, such as 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. The high-pressure exhaust gas recirculation passage 36 is provided with a high-pressure EGR valve 39. Essentially, exhaust gas recirculation is performed via the low-pressure exhaust gas recirculation passage 35 in the supercharging range, and via the high-pressure exhaust gas recirculation passage 36 in the non-supercharging range.

[0017] In addition to the air flow meter 24 and air-fuel ratio sensor 33, detection signals from sensors such as a crank angle sensor 41 for detecting engine speed, a water temperature sensor 42 for detecting coolant temperature, and a boost pressure sensor 43 for detecting boost pressure are input to the engine controller 8. Based on these detection signals and requests from the other controllers 7 and 9, the engine controller 8 optimally controls the fuel injection amount and injection timing, ignition timing, the opening of the throttle valve 22, boost pressure, etc.

[0018] 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 electricity. The generated electricity is consumed by the traction motor generator 4, and surplus electricity is stored in the battery 5. Furthermore, when the vehicle is decelerating or going downhill, the traction motor generator 4 is controlled to generate electricity, and the obtained electricity is recovered in the battery 5.

[0019] On the other hand, depending on the conditions, the internal combustion engine 2 connected to the power-generator motor-generator 1 may be motored by the power running of the power-generator motor-generator 1. For example, when the SOC of the battery 5 reaches a predetermined upper limit SOC value during regenerative control of the traction motor-generator 4, motoring of the internal combustion engine 2 using the power-generator motor-generator 1 is performed, and regenerative power is consumed in order to avoid deterioration of the battery 5 due to overcharging. Note that such power consumption by motoring can be performed, for example, while traveling downhill while actually performing regeneration, or it may be performed before reaching a downhill road in order to predict a downhill road and lower the SOC of the battery 5 in advance.

[0020] When the internal combustion engine 2 is motored externally in this manner, as described above, negative pressure develops in the cylinder 13, particularly during the downward stroke of the piston 11, and oil in the crankcase 20 tends to leak into the combustion chamber 10. This results in increased oil consumption and the discharge of hydrocarbons contained in the oil to the outside. To suppress the development of such negative pressure, in this embodiment, when the internal combustion engine 2 is motored by the power-generating motor-generator 1, the motor-generator section 12c of the turbocharger 12 is driven to rotate and the compressor 12a pressurizes and delivers intake air. This increases the pressure in the intake air collector 21a, which in turn increases the pressure in the combustion chamber 10 during motoring. This reduces the amount of oil that leaks from the crankcase 20 into the combustion chamber 10.

[0021] 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. Maintaining a positive pressure in this way reliably suppresses the movement of oil from the crankcase 20 toward the combustion chamber 10 due to the pressure difference. However, even if the pressure inside the combustion chamber 10 becomes negative during the downward stroke of the piston 11, the pressure difference between the pressure inside the crankcase 20 and the pressure inside the combustion chamber 10 is reduced due to the pressurization of the intake air caused by the drive of the turbocharger 12, thereby achieving the effect of reducing the movement of oil toward the combustion chamber 10.

[0022] On the other hand, powering the motor generator section 12c of the turbocharger 12 while the internal combustion engine 2 is motoring is also advantageous in terms of power consumption. In other words, the power consumption of the motor generator section 12c is added to the power consumption of the power-generating motor generator 1, which accelerates the consumption of regenerative power on downhill roads or the like or a decrease in the SOC of the battery 5.

[0023] More precisely, the turbocharger 12 performs a supercharging operation, thereby reducing the pumping loss of the internal combustion engine 2 and reducing the power consumption of the power-generating motor generator 1 required for motoring the internal combustion engine 2. However, the total power consumption becomes relatively large when the power consumption of the motor generator section 12c is added.

[0024] FIG. 3 is an explanatory diagram illustrating the power consumption of (a) a comparative example in which the electrically assisted turbocharger 12 is not used, and (b) an embodiment in which a supercharging operation by the electrically assisted turbocharger 12 is added.

[0025] In the case of comparative example (a), if the required power consumption is W0 and the power consumption of the power-generating motor-generator 1 during motoring is W1, then there is a relationship of W0 = W1. Also, at this time, the pressure P1 inside the cylinder 13 is "P1 < 0," i.e., a negative pressure. The power consumption W1 and the pressure P1 are correlated with each other, and the greater the power consumption W1 is increased by controlling the opening of the throttle valve 22, the lower the pressure P1 becomes (the more negative pressure develops). In other words, the greater the power consumption W1, the greater the oil consumption.

[0026] In the case of Example (b), if the required power consumption is W0, the power consumption of the power-generating motor-generator 1 during motoring is W2, and the power consumption of the motor-generator section 12c of the turbocharger 12 is W3, then the relationship W0 = W2 + W3 holds. Therefore, the relationship W1 > W2 holds. That is, for the same required power consumption W0, the power consumption W2 of the power-generating motor-generator 1 is smaller than the power consumption W1 in Comparative Example (a) by the amount of the power consumption W3 of the motor-generator section 12c. At this time, the pressure P2 inside the cylinder 13 is higher than the pressure P1 in Comparative Example (a). This pressure P2 also correlates with the power consumption W2 required for motoring. That is, when pressure P2 is higher than P1, the power consumption W2 becomes smaller than W1.

[0027] Thus, in the above embodiment, assuming that the same required power consumption W0 is consumed, by driving the turbocharger 12 with the motor generator section 12c, a high pressure P2 can be obtained within the cylinder 13, and oil leakage from the crankcase 20 can be suppressed.

[0028] Furthermore, if the pressure inside the cylinder 13 is allowed to be the same as in the comparative example, the total power consumption (W2+W3) will be greater than the power consumption W1 in the comparative example. This means that, for example, the motoring time required to reduce the SOC of the battery 5 to a certain level will be shorter, and as a result, the amount of oil that moves from the crankcase 20 to the combustion chamber 10 during motoring will be less.

[0029] The pumping loss during motoring (i.e., the power consumption W2 required for motoring) is affected by, for example, the opening of the throttle valve 22, the opening and closing characteristics (opening / closing timing, lift amount, etc.) of the intake valve 14 and the exhaust valve 15 by the variable valve mechanisms 18 and 19, the opening of the high-pressure EGR valve 39 in the high-pressure exhaust gas recirculation passage 36, and the like. In a preferred embodiment, the pumping loss is appropriately set by controlling at least one of these elements. Then, by combining control of these elements with control of the motor-generator unit 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.

[0030] While the internal combustion engine 2 is in combustion operation, the electrically assisted turbocharger 12 can be used in a normal manner. That is, the response of supercharging can be improved by powering the motor generator unit 12c at the start of supercharging or when exhaust energy is insufficient. When exhaust energy is excessive, exhaust energy can be recovered by regenerative control of the motor generator unit 12c.

[0031] Although one embodiment in which the present invention is applied to a series hybrid vehicle has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, ,above In the above embodiment, an electrically assisted turbocharger is used as the electric compressor, but any type of electric compressor may be used, including a relatively low-pressure so-called blower. It does not necessarily have to be a supercharger used for supercharging during combustion operation, and a configuration with an electric compressor for pressure adjustment during motoring is also possible. [Explanation of symbols]

[0032] 1...Power generating motor generator 2...Internal combustion engine 4...Traction motor generator 5. Battery 6...Controller 8...Engine controller 10...Combustion chamber 12...Turbocharger 12a...Compressor 12b...Turbine 12c...Motor generator section 18,19...Variable valve mechanism 22...Throttle valve 39...High-pressure EGR valve

Claims

1. A series hybrid vehicle equipped with a power generating motor generator, an internal combustion engine that drives the power generating motor generator to generate electricity, and a traction motor generator that drives drive wheels using the generated electricity, An electric compressor is provided in the intake system of the internal combustion engine, When consumption of surplus power is required, the internal combustion engine is motored by powering the power generating motor generator, which consumes power; During motoring, the electric compressor is operated to consume power and increase the pressure of intake air supplied to the combustion chamber of the internal combustion engine. A method for controlling a hybrid vehicle.

2. The electric compressor is an electrically assisted turbocharger having a motor generator unit coaxially arranged with the turbine and compressor. The method for controlling a hybrid vehicle according to claim 1 .

3. Operate the electric compressor so that the combustion chamber of the internal combustion engine is under positive pressure.

3. A method for controlling a hybrid vehicle according to claim 1.

4. The pressure in the combustion chamber is controlled by combining control of at least one of the opening and closing characteristics of the intake valve or exhaust valve, the opening of the throttle valve in the intake passage, and the opening of the exhaust gas recirculation control valve in the exhaust gas recirculation passage that guides EGR gas from the exhaust passage upstream of the turbine to the intake passage downstream of the compressor with control of the electrically assisted turbocharger. The method for controlling a hybrid vehicle according to claim 2.

5. A motor generator for generating electricity; an internal combustion engine that drives the power-generating motor generator to generate electricity; a driving motor generator that drives drive wheels using the generated electric power; an electric compressor provided in an intake system of an internal combustion engine; A controller; In a series hybrid vehicle equipped with The above controller is When consumption of surplus power is required, the internal combustion engine is motored by powering the power generating motor generator, which consumes power; During motoring, the electric compressor is operated to consume power and increase the pressure of intake air supplied to the combustion chamber of the internal combustion engine. A control device for a hybrid vehicle.

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