Hybrid vehicle

Abstract

The present invention addresses the problem of providing a hybrid vehicle in which freezing of moisture in blow-by gas is suppressed without affecting driving performance. A hybrid vehicle is provided with: an engine and a motor; a clutch that switches between an engaged state in which power from the engine can be transmitted to the drive wheels and a disengaged state in which power cannot be transmitted; a supercharger including a compressor and a turbine disposed in an intake passage and an exhaust passage of the engine, respectively, and a variable nozzle mechanism for adjusting the flow rate of exhaust gas flowing into the turbine according to the opening degree of a nozzle; an intercooler provided downstream of the compressor in the intake passage; a return passage that causes blow-by flow generated by the engine to flow to the intake passage upstream of the compressor; a communication passage, one end of which is connected to the intake passage downstream of the compressor and upstream of the intercooler, and the other end of which is connected to the return passage; and an on-off valve that opens and closes the communication passage.

Description

Technical Field

[0001] This invention relates to a hybrid vehicle. Background Technology

[0002] Hybrid vehicles sometimes have engines equipped with superchargers. The supercharger has a compressor and a turbine, as well as a variable nozzle mechanism that adjusts the flow rate of exhaust gas flowing into the turbine by adjusting the opening of the nozzles (e.g., see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-145748 Summary of the Invention

[0004] Hybrid vehicles sometimes have a return path that directs blow-by air generated by the engine into the intake passage, located upstream of the compressor. Moisture in the blow-by air flowing through this return path can sometimes freeze and form ice. This ice can potentially collide with the compressor, affecting its durability. Therefore, it is desirable to suppress this freezing of moisture in the blow-by air, but it is desirable to achieve this without affecting the driving performance of the hybrid vehicle.

[0005] Therefore, the object of the present invention is to provide a hybrid vehicle that suppresses the freezing of moisture in blow-by gas without affecting driving performance.

[0006] The above objective can be achieved by a hybrid vehicle comprising: an engine and an electric motor capable of transmitting power to drive wheels; a clutch that switches between an engaged state capable of transmitting power from the electric motor to the drive wheels and a disengaged state capable of transmitting power from the engine to the drive wheels, and a disengaged state in which power cannot be transmitted; a turbocharger including a compressor and a turbine respectively disposed in the intake and exhaust passages of the engine, and a variable nozzle mechanism for adjusting the flow rate of exhaust gas flowing into the turbine by adjusting the opening of the nozzles; and an intercooler disposed in the intake passage. The compressor is located further downstream; a return flow path directs the blow-by air generated by the engine to the intake passage, which is located further upstream than the compressor; a connecting passage, one end of which is connected to the intake passage, which is located further downstream than the compressor and further upstream than the intercooler, and the other end of which is connected to the return flow path; an on / off valve that opens and closes the connecting passage; and a control device that, when the clutch is in the disengaged state, the motor is running, and the engine is in operation, controls the opening of the nozzles based on the variable nozzle mechanism to pressurize the intake air by the compressor and open the on / off valve.

[0007] One end of the connecting passage may be closer to the compressor than the intercooler.

[0008] The control device can control the nozzle opening to a minimum value when the clutch is in the disengaged state, the motor is running, and the engine is in operation.

[0009] Invention Effects

[0010] According to the present invention, a hybrid vehicle is provided that can suppress the freezing of moisture in blow-by gas without affecting driving performance. Attached Figure Description

[0011] Figure 1 This is a schematic structural diagram of the hybrid vehicle in this embodiment.

[0012] Figure 2 This is a schematic diagram of the engine's structure.

[0013] Figure 3 This is a flowchart illustrating blow-by temperature control performed by the ECU.

[0014] Figure 4 This is a diagram illustrating the airflow during intake when the valve is open. Detailed Implementation

[0015] [Brief Structure of Hybrid Vehicles]

[0016] Figure 1 This is a schematic structural diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a clutch 40, an electric motor 45, and a transmission 50 are sequentially arranged in the power transmission path from the engine 10 to the drive wheels 60. The engine 10 and the electric motor 45 are equipped as the driving source for the hybrid vehicle 1. The engine 10 can transmit power to the drive wheels 60 via the electric motor 45, the transmission 50, and the differential 55. The electric motor 45 can transmit power to the drive wheels 60 via the transmission 50 and the differential 55. The engine 10 is, for example, a gasoline engine, but it can also be a diesel engine. The transmission 50 includes a torque converter and an automatic transmission.

[0017] Clutch 40 is located between engine 10 and motor 45 on the same power transmission path. Clutch 40 receives hydraulic supply from the disengaged state and becomes engaged, thereby connecting the power transmission between engine 10 and motor 45. In other words, when clutch 40 is engaged, the power of engine 10 can be transmitted to drive wheel 60. Clutch 40 becomes disengaged when hydraulic supply stops, cutting off the power transmission between engine 10 and motor 45. In other words, when clutch 40 is disengaged, engine 10 is cut off from the power transmission path, and the power of engine 10 cannot be transmitted to drive wheel 60.

[0018] The motor 45 is connected to the battery 70 via the PCU 65. The motor 45 functions as the driving power source for the hybrid vehicle 1 based on the power supplied from the battery 70. Furthermore, the motor 45 also functions as a generator to charge the battery 70 based on power transmitted from the engine 10 or the drive wheels 60.

[0019] PCU65 is controlled by ECU100, described later. During traction operation with the output torque of motor 45, PCU65 converts the DC voltage of battery 70 to AC voltage to adjust the power supplied to motor 45. During regenerative operation with motor 45 generating electricity, PCU65 converts the AC voltage from motor 45 to DC voltage to adjust the regenerative power supplied to battery 70.

[0020] The hybrid vehicle 1 is equipped with an Electronic Control Unit (ECU) 100, which serves as the vehicle's control device. The ECU 100 is an electronic control unit that includes arithmetic processing circuits for various calculations related to vehicle driving control and a memory storing control programs or data. The ECU 100 is an example of a control device. While details will be described later, the ECU 100 performs blow-by temperature control.

[0021] ECU 100 enables the hybrid vehicle 1 to operate in either electric motor driving mode or hybrid driving mode. In electric motor driving mode, ECU 100 stops the engine 10 and disengages the clutch 40, utilizing the power of the electric motor 45 for driving. In hybrid driving mode, the clutch 40 is engaged, and the vehicle utilizes at least the power of the engine 10 for driving. Furthermore, in hybrid driving mode, the output of the electric motor 45 can be used to assist in driving the engine 10.

[0022] [Engine's general structure]

[0023] Figure 2 This is a schematic diagram of the structure of engine 10. Engine 10 is a spark-ignition four-cylinder gasoline engine, which is an example of an internal combustion engine, but it is not limited to this. It can also be an engine other than a four-cylinder engine, such as a compression-ignition diesel engine or other types of engines.

[0024] The engine 10 includes an internal combustion engine body 11, a cylinder head cover 12, a crankcase 13, pistons 14, a combustion chamber 15, an intake passage 16, an exhaust passage 19, a turbocharger 20, an intercooler 22, and a throttle valve 24. The internal combustion engine body 11 has cylinders 11a, a cylinder head cover 12 disposed above the cylinders 11a, and a crankcase 13 disposed below the cylinders 11a. The pistons 14 reciprocate within the combustion chamber 15 of the cylinders 11a. Intake passages 16 and exhaust passages 19 are connected to each cylinder of the internal combustion engine body 11. Figure 2 Only a portion of the exhaust passage 19 is shown in the image. The air filter 17 is installed near the inlet portion of the intake passage 16.

[0025] The supercharger 20 includes a compressor 20a, a turbine 20b, and a variable nozzle mechanism 20c. The compressor 20a is located downstream of the air filter 17 in the intake passage 16 and pressurizes the intake air. The compressor 20a and turbine 20b are integrally connected via a connecting shaft. The turbine 20b is located in the exhaust passage 19. The exhaust gas from the turbine 20b causes the compressor 20a and turbine 20b to rotate together, thereby pressurizing the intake air.

[0026] The variable nozzle mechanism 20c adjusts the flow rate of exhaust gas flowing into the turbine 20b by adjusting the nozzle opening. The nozzle opening, controlled by the variable nozzle mechanism 20c, is controlled by the ECU 100. If the nozzle opening decreases, the spacing between the nozzle blades on the turbine 20b narrows, and the flow path area of ​​the exhaust gas flowing into the turbine 20b decreases. As a result, the flow rate of the exhaust gas flowing into the turbine 20b increases, and the rotational speed of the turbine 20b increases. On the other hand, if the nozzle opening increases, the spacing between the nozzle blades on the turbine 20b increases, and the flow path area of ​​the exhaust gas flowing into the turbine 20b increases. As a result, the flow rate of the exhaust gas flowing into the turbine 20b decreases, and the rotational speed of the turbine 20b decreases. With this increase or decrease in the rotational speed of the turbine 20b, the rotational speed of the compressor 20a also increases or decreases, and the intake boost pressure also increases or decreases.

[0027] Intercooler 22 is located downstream of compressor 20a in intake passage 16 to cool the pressurized air. Electronically controlled throttle valve 24 is located downstream of intercooler 22 and is controlled by ECU 100.

[0028] A guide passage 31 is provided inside cylinder 11a. A storage space 32 communicating with the guide passage 31 is provided inside cylinder head cover 12. An oil separator 33 communicating with the storage space 32 is provided on cylinder head cover 12. One end of a return passage 34 is connected to the oil separator 33. The other end of the return passage 34 is connected to the intake passage 16, which is downstream of the air filter 17 and upstream of the compressor 20a.

[0029] If the pressure upstream of compressor 20a becomes negative, the blow-by gas is drawn to oil separator 33 via guide passage 31 and accumulation space 32. In oil separator 33, oil mist in the blow-by gas is separated. The blow-by gas separated from the oil mist flows back to intake passage 16 via return passage 34. Thus, the blow-by gas is sent into combustion chamber 15 via intake passage 16 for combustion.

[0030] A connecting passage 38 is provided, connecting the intake passage 16 and the return passage 34. One end 381 of the connecting passage 38 is connected to the intake passage 16, downstream of the compressor 20a and upstream of the intercooler 22. The other end 382 of the connecting passage 38 is connected to the return passage 34. An opening / closing valve 39 is provided on the connecting passage 38 to open and close the passage. The opening and closing of the opening / closing valve 39 is controlled by the ECU 100. In hybrid driving mode or electric motor driving mode when the engine 10 is stopped, the opening / closing valve 39 is controlled to be closed.

[0031] [Gas leakage and temperature rise control]

[0032] Figure 3 This is a flowchart illustrating the blow-by temperature control performed by ECU 100. This control is repeatedly executed during ignition. ECU 100 determines whether clutch 40 is disengaged (step S1). If "no" is found in step S1, this control ends.

[0033] If "Yes" is received in step S1, the ECU100 determines whether the driving mode is the electric motor driving mode (step S2). That is, it determines whether the driving mode is driven solely by the power transmitted from the motor 45 to the drive wheels 60. If "No" is received in step S2, the control process ends.

[0034] If "yes" is received in step S2, the ECU 100 determines whether the engine 10 is being driven (step S3). The engine 10 being driven means that the engine 10 is performing fuel injection and igniting the air-fuel mixture. If "no" is received in step S3, this control ends. Furthermore, "yes" in steps S1 to S3 refers to, for example, a situation where the engine 10 is intermittently driven in electric motor driving mode to maintain the engine 10 temperature above a specified temperature.

[0035] If "yes" is selected in step S3, the ECU100 controls the nozzle opening to its minimum value via the variable nozzle mechanism 20c (step S4). As a result, the turbine 20b and compressor 20a reach their maximum speeds, and the compressor 20a pressurizes the intake air. Consequently, the intake air is compressed, and its temperature rises.

[0036] Next, ECU100 opens the on / off valve 39 (step S5). As a result, part of the high-temperature intake air from compressor 20a flows into return passage 34 via connection passage 38. Figure 4 This is an illustration of the airflow when the on / off valve 39 is open.

[0037] Thus, part of the high-temperature intake air flows into the return flow path 34. Furthermore, as described above, one end 381 of the connecting passage 38 is connected to the intake passage 16 further downstream of the compressor 20a and further upstream of the intercooler 22. Therefore, before the high-temperature intake air from the compressor 20a is cooled by the intercooler 22, it flows into the return flow path 34 via the connecting passage 38. This causes the blow-by air in the return flow path 34 to heat up, suppressing the freezing of moisture in the blow-by air. Therefore, collisions between ice and the compressor 20a are prevented, ensuring the durability of the compressor 20a.

[0038] Furthermore, as described above, when "yes" is true in steps S1 to S3, the nozzle opening is controlled to a minimum by the variable nozzle mechanism 20c and the on / off valve 39 is opened, thereby suppressing the freezing of moisture in the blow-by gas. Here, "yes" in steps S1 to S3 refers to a state where the engine 10 is in motion, but the motion of the engine 10 does not affect the driving performance of the hybrid vehicle 1. For example, when the vehicle is powered by the engine 10, if the nozzle opening is controlled and the on / off valve 39 is opened, a portion of the pressurized intake air may not be delivered to the engine 10 but instead circulate between the connecting passage 38 and the compressor 20a. As a result, the torque of the engine 10 may become unstable, affecting the driving performance of the hybrid vehicle 1. In this embodiment, when "yes" is true in steps S1 to S3, the nozzle opening is controlled and the on / off valve 39 is opened, thus suppressing the freezing of moisture in the blow-by gas without affecting the driving performance of the hybrid vehicle 1.

[0039] Furthermore, one end 381 of the connecting passage 38 is closer to the compressor 20a than the intercooler 22. Therefore, before the heat from the intake air, which becomes high-temperature air by the compressor 20a, is taken away by the intake passage 16, the high-temperature intake air flows into the return passage 34. Thus, the blow-by air in the return passage 34 is further heated, suppressing the freezing of moisture in the blow-by air. Additionally, the shorter the length of the connecting passage 38, the better. This is because a longer connecting passage 38 results in more heat being taken away from the intake air.

[0040] In the above embodiment, the nozzle opening is controlled to a minimum value by the variable nozzle mechanism 20c, but it is not limited to this. It is sufficient to control the nozzle opening to at least the extent that the intake air is pressurized. This is because if the intake air is pressurized, the temperature of the intake air increases. For example, as long as the nozzle opening in the above case is smaller than the nozzle opening controlled when the engine 10 is running in the naturally aspirated region in the mixed driving mode, the intake air is pressurized.

[0041] The hybrid vehicle 1 has an engine 10 and an electric motor 45 as its driving power source, but is not limited to this type of hybrid vehicle. For example, it could also be a hybrid vehicle with an engine and two electric motors connected to each other via a planetary gear mechanism and a clutch having the above-mentioned functions.

[0042] While the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments. Various modifications and alterations are possible within the scope of the spirit of the present invention as set forth in the claims.

[0043] Symbol Explanation

[0044] 1-Hybrid vehicle, 10-Engine, 11-Internal combustion engine body, 16-Intake passage, 19-Exhaust passage, 20-Turbocharger, 20a-Compressor, 20b-Turbine, 20c-Variable nozzle mechanism, 22-Intercooler, 34-Return passage, 38-Connecting passage, 39-On / off valve, 100-ECU (Control Unit).

Claims

1. A hybrid vehicle, characterized in that, have: Engine and electric motor, which can transmit power to the drive wheels; The clutch switches between an engaged state, in which it can transmit power from the motor to the drive wheel, and an disengaged state, in which it can transmit power from the engine to the drive wheel, and in which it cannot transmit power. A turbocharger includes a compressor and a turbine respectively disposed in the intake and exhaust passages of the engine, and a variable nozzle mechanism for adjusting the flow rate of exhaust gas flowing into the turbine by means of the nozzle opening. An intercooler is located downstream of the compressor in the intake passage; The return flow path directs the blow-by airflow generated by the engine to the intake passage, which is located upstream of the compressor. A connecting passage, one end of which is connected to the intake passage downstream of the compressor and upstream of the intercooler, and the other end of which is connected to the return passage. An on / off valve that opens and closes the connecting passage; and A control device that, when the clutch is in the disengaged state, the motor is running, and the engine is in operation, controls the opening of the nozzle based on the variable nozzle mechanism to pressurize the intake air by the compressor and open the on / off valve.

2. The hybrid vehicle according to claim 1, characterized in that, One end of the connecting passage is closer to the compressor than the intercooler.

3. The hybrid vehicle according to claim 2, characterized in that, The control device controls the nozzle opening to a minimum value when the clutch is in the disengaged state, the motor is running, and the engine is in operation.

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