Hybrid vehicles

Abstract

The objective is to provide a hybrid vehicle that suppresses the freezing of moisture in blow-by gas without affecting driving performance. [Solution] The hybrid vehicle includes an engine and a motor, a clutch that switches between an engaged state that can transmit power from the engine to the drive wheels and a disengaged state that cannot transmit power, a supercharger including a compressor and a turbine arranged in the intake passage and exhaust passage of the engine, respectively, and a variable nozzle mechanism that adjusts the flow velocity of exhaust gas flowing into the turbine by the opening of the nozzle, an intercooler provided downstream of the compressor in the intake passage, a return passage that flows blow-by gas generated by the engine to the intake passage upstream of the compressor, a connecting passage whose one end is connected downstream of the compressor in the intake passage and upstream of the intercooler, and whose other end is connected to the return passage, and an on / off valve that opens and closes the connecting passage.

Description

Technical Field

[0001] The present invention relates to a hybrid vehicle.

Background Art

[0002] The engine of a hybrid vehicle may be provided with a supercharger. The supercharger has a compressor and a turbine, and further has a variable nozzle mechanism for adjusting the flow velocity of the exhaust gas flowing into the turbine by the opening degree of the nozzle (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A hybrid vehicle may be provided with a recirculation passage for flowing the blow-by gas generated by the engine to the upstream side of the compressor in the intake passage. Moisture in the blow-by gas flowing through the recirculation passage may freeze to form ice blocks. There is a risk that these ice blocks may collide with the compressor and affect durability. Therefore, it is desirable to suppress the freezing of moisture in such blow-by gas, but it is desirable to be able to achieve this without affecting the running performance of the hybrid vehicle.

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

Means for Solving the Problems

[0006] The above objective is to provide a supercharger including an engine and motor capable of transmitting power to the drive wheels, 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 compressor and turbine arranged in the intake passage and exhaust passage of the engine, respectively, and a variable nozzle mechanism that adjusts the flow velocity of the exhaust gas flowing into the turbine by the nozzle opening, an intercooler provided downstream of the compressor in the intake passage, and a blowback valve generated by the engine. This can be achieved by a hybrid vehicle comprising: a recirculation passage that flows exhaust gas to the intake passage 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 recirculation passage; an on-off valve that opens and closes the connecting passage; and a control device that controls the opening degree of the nozzle by the variable nozzle mechanism and opens the on-off valve so that the intake air is supercharged by the compressor when the clutch is disengaged, the vehicle is driven by the motor, and the engine is running.

[0007] The one end of the communication passage may be closer to the compressor than to the intercooler.

[0008] The control device may control the nozzle opening to a minimum value when the clutch is disengaged, the vehicle is being driven by the motor, and the engine is running. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a hybrid vehicle that suppresses the freezing of moisture in blow-by gas without affecting driving performance. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the hybrid vehicle in this embodiment. [Figure 2] This is a schematic diagram of the engine's configuration. [Figure 3]This flowchart illustrates the blow-by gas temperature control performed by the ECU. [Figure 4] This is a diagram illustrating the airflow from the intake when the valve is open. [Modes for carrying out the invention]

[0011] [Overall configuration of a hybrid vehicle] Figure 1 is a schematic diagram of the hybrid vehicle 1. The hybrid vehicle 1 has a power transmission path from the engine 10 to the drive wheels 60, in which a clutch 40, a motor 45, and a transmission 50 are provided in that order. The engine 10 and motor 45 are mounted as the drive source for the hybrid vehicle 1. The engine 10 can transmit power to the drive wheels 60 via the motor 45, transmission 50, and differential gear 55. The motor 45 can transmit power to the drive wheels 60 via the transmission 50 and differential gear 55. The engine 10 is, for example, a gasoline engine, but it may also be a diesel engine. The transmission 50 includes a torque converter and an automatic transmission.

[0012] The clutch 40 is located between the engine 10 and the motor 45 on the same power transmission path. The clutch 40 engages from a disengaged state when hydraulic pressure is supplied, connecting the power transmission between the engine 10 and the motor 45. In other words, when the clutch 40 is engaged, the power of the engine 10 can be transmitted to the drive wheels 60. The clutch 40 disengages in response to the cessation of hydraulic pressure supply, interrupting the power transmission between the engine 10 and the motor 45. In other words, when the clutch 40 is disengaged, the engine 10 is disconnected from the power transmission path, and the power of the engine 10 cannot be transmitted to the drive wheels 60.

[0013] The motor 45 is connected to the battery 70 via the PCU 65. The motor 45 functions as a power source for the hybrid vehicle 1 in response to power supplied from the battery 70. Furthermore, the motor 45 also functions as a generator that charges the battery 70 in response to power transmission from the engine 10 and the drive wheels 60.

[0014] The PCU65 is controlled by the ECU100, which will be described later. In the case of powered operation where the motor 45 outputs torque, the PCU65 converts the DC voltage of the battery 70 to an AC voltage and adjusts the power supplied to the motor 45. In the case of regenerative operation where the motor 45 generates electricity, the PCU65 converts the AC voltage from the motor 45 to a DC voltage and adjusts the regenerative power supplied to the battery 70.

[0015] Hybrid vehicle 1 is equipped with an ECU (Electronic Control Unit) 100 as the vehicle's control device. The ECU 100 is an electronic control unit comprising an arithmetic processing circuit that performs various calculations related to vehicle driving control, and a memory that stores control programs and data. The ECU 100 is an example of a control device. The ECU 100 performs blow-by gas temperature rise control, which will be described in more detail later.

[0016] The ECU 100 drives the hybrid vehicle 1 in either motor-only driving mode or hybrid driving mode. In motor-only driving mode, the ECU 100 stops the engine 10, releases the clutch 40, and drives the vehicle using the power of the motor 45. In hybrid driving mode, the clutch 40 is engaged and the vehicle drives using at least the power of the engine 10. In hybrid driving mode, the output of the motor 45 can also assist in driving the engine 10.

[0017] [Engine Overview] Figure 2 is a schematic diagram of the engine 10. Engine 10 is a spark-ignition type 4-cylinder gasoline engine, which is an example of an internal combustion engine, but is not limited to this. It may also be a type of engine other than a 4-cylinder engine, such as a compression-ignition type diesel engine.

[0018] The engine 10 includes an engine body 11, a head cover 12, a crankcase 13, a piston 14, a combustion chamber 15, an intake passage 16, an exhaust passage 19, a supercharger 20, an intercooler 22, and a throttle valve 24. The engine body 11 has a cylinder 11a, a head cover 12 provided above the cylinder 11a, and a crankcase 13 provided below the cylinder 11a. The piston 14 reciprocates within the combustion chamber 15 of the cylinder 11a. An intake passage 16 and an exhaust passage 19 are connected to each cylinder of the engine body 11. The exhaust passage 19 shows only a part thereof in FIG. 2. An air cleaner 17 is attached near the inlet portion of the intake passage 16.

[0019] The supercharger 20 has a compressor 20a, a turbine 20b, and a variable nozzle mechanism 20c. The compressor 20a is installed on the downstream side of the air cleaner 17 in the intake passage 16 and supercharges the intake air. The compressor 20a is integrally connected to the turbine 20b via a connecting shaft. The turbine 20b is arranged in the exhaust passage 19. The exhaust passing through the turbine 20b causes the compressor 20a to rotate together with the turbine 20b, and the intake air is supercharged by the compressor 20a.

[0020] The variable nozzle mechanism 20c adjusts the flow velocity of the exhaust flowing into the turbine 20b by the opening degree of the nozzle. The opening degree of the nozzle by the variable nozzle mechanism 20c is controlled by the ECU 100. When the opening degree of the nozzle becomes small, the interval between the nozzle vanes provided on the turbine 20b narrows, and the flow area of the exhaust flowing into the turbine 20b becomes small. As a result, the flow velocity of the exhaust flowing into the turbine 20b increases, and the rotational speed of the turbine 20b increases. On the other hand, when the opening degree of the nozzle becomes large, the interval between the nozzle vanes provided on the turbine 20b becomes large, and the flow area of the exhaust flowing into the turbine 20b becomes large. As a result, the flow velocity of the exhaust flowing into the turbine 20b decreases, and the rotational speed of the turbine 20b decreases. Along with such an increase or decrease in the rotational speed of the turbine 20b, the rotational speed of the compressor 20a also increases or decreases, and the supercharging pressure of the intake air also increases or decreases.

[0021] The intercooler 22 is installed downstream of the compressor 20a in the intake passage 16 and cools the supercharged air. The electronically controlled throttle valve 24 is provided downstream of the intercooler 22 and is controlled by the ECU 100.

[0022] A guide passage 31 is provided in the cylinder 11a. An accumulation space 32 communicating with the guide passage 31 is provided in the head cover 12. An oil separator 33 communicating with the accumulation space 32 is provided in the 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 downstream of the air cleaner 17 in the intake passage 16 and upstream of the compressor 20a.

[0023] When the pressure upstream of the compressor 20a becomes negative pressure, the blow-by gas is sucked into the oil separator 33 through the guide passage 31 and the accumulation space 32. In the oil separator 33, the oil mist in the blow-by gas is separated. The blow-by gas from which the oil mist has been separated is refluxed to the intake passage 16 through the return passage 34. In this way, the blow-by gas is sent into the combustion chamber 15 through the intake passage 16 and used for combustion.

[0024] A communication passage 38 that connects the intake passage 16 and the return passage 34 is provided. One end 381 of the communication passage 38 is connected downstream of the compressor 20a in the intake passage 16 and upstream of the intercooler 22. The other end 382 of the communication passage 38 is connected to the return passage 34. An on-off valve 39 for opening and closing the communication passage 38 is provided in the communication passage 38. The opening and closing of the on-off valve 39 are controlled by the ECU 100. In the hybrid driving mode or the motor driving mode when the engine 10 is stopped, the on-off valve 39 is controlled to be in a closed state.

[0025] [Blow-by Gas Temperature Rise Control] Figure 3 is a flowchart illustrating the blow-by gas temperature rise control performed by the ECU 100. This control is repeatedly executed while the ignition is on. The ECU 100 determines whether the clutch 40 is in the disengaged state (step S1). If the answer in step S1 is No, this control terminates.

[0026] If the answer in step S1 is Yes, the ECU 100 determines whether the driving mode is motor driving mode (step S2). That is, it determines whether the vehicle is being driven by power transmitted only from the motor 45 to the drive wheels 60. If the answer in step S2 is No, this control process ends.

[0027] If the answer in step S2 is Yes, the ECU 100 determines whether the engine 10 is running or not (step S3). The engine 10 is running when it is in a state where fuel injection and ignition of the air-fuel mixture are being performed. If the answer in step S3 is No, this control is terminated. Note that if the answer in steps S1 to S3 is Yes, for example, when the engine 10 is run intermittently in motor driving mode to maintain the temperature of the engine 10 above a predetermined temperature.

[0028] If the answer in step S3 is Yes, the ECU 100 controls the nozzle opening to the minimum value using the variable nozzle mechanism 20c (step S4). This causes the rotational speed of the turbine 20b and compressor 20a to reach their maximum, and the intake air is supercharged by the compressor 20a. As a result, the intake air is compressed and its temperature rises.

[0029] Next, the ECU 100 opens the on-off valve 39 (step S5). As a result, some of the intake air, which has been heated by the compressor 20a, flows into the recirculation passage 34 via the communication passage 38. Figure 4 is an explanatory diagram of the intake air flow when the on-off valve 39 is open.

[0030] As a result, some of the intake air, which has become hot, flows into the recirculation passage 34. Also, as described above, 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. Therefore, the intake air, which has become hot due to the compressor 20a, flows into the recirculation passage 34 via the connecting passage 38 before it is cooled by the intercooler 22. This causes the blow-by gas in the recirculation passage 34 to heat up, suppressing the freezing of moisture in the blow-by gas. Consequently, collisions of ice chunks with the compressor 20a are avoided, and the durability of the compressor 20a is ensured.

[0031] Furthermore, as described above, if the answer to steps S1 to S3 is Yes, the variable nozzle mechanism 20c controls the nozzle opening to the minimum value, opening the on-off valve 39, thereby suppressing the freezing of moisture in the blow-by gas. Here, the answer to steps S1 to S3 is Yes, which means that the engine 10 is running, but the engine 10's operation does not affect the drivability of the hybrid vehicle 1. For example, if the nozzle opening is controlled and the on-off valve 39 opens while the vehicle is being driven by the engine 10, some of the supercharged intake air may not be sent to the engine 10 but instead circulate between the communication passage 38 and the compressor 20a. As a result, the torque of the engine 10 may become unstable, potentially affecting the drivability of the hybrid vehicle 1. In this embodiment, since the nozzle opening is controlled and the on-off valve 39 opens when the answer to steps S1 to S3 is Yes, the freezing of moisture in the blow-by gas is suppressed without affecting the drivability of the hybrid vehicle 1.

[0032] Furthermore, one end 381 of the connecting passage 38 is closer to the compressor 20a than to the intercooler 22. Therefore, the hot intake air flows into the recirculation passage 34 before much of the heat from the intake air, which has been heated to a high temperature by the compressor 20a, is taken away by the intake passage 16. As a result, the blow-by gas in the recirculation passage 34 is heated more, and the freezing of moisture in the blow-by gas is suppressed. It should be noted that a shorter length of the connecting passage 38 is preferable. This is because if the connecting passage 38 is long, a larger amount of heat from the intake air is taken away by the connecting passage 38.

[0033] In the above embodiment, the nozzle opening was controlled to the minimum value by the variable nozzle mechanism 20c, but the embodiment is not limited to this. It is sufficient that the nozzle opening is controlled to the extent that the intake air is supercharged. This is because the temperature of the intake air rises when it is supercharged. For example, in the hybrid driving mode, the nozzle opening in the above case should be smaller than the nozzle opening controlled when the engine 10 is running in the naturally aspirated range, so that the intake air is supercharged.

[0034] Hybrid vehicle 1 is equipped with an engine 10 and one motor 45 as a driving power source, but is not limited to such a hybrid vehicle. For example, a hybrid vehicle may be equipped with an engine and two motors connected to each other via a planetary gear mechanism and a clutch having the above-described function.

[0035] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0036] 1. Hybrid vehicle 10 Engines 11. Engine body 16 Intake passage 19 Exhaust passage 20 Supercharger 20a compressor 20b Turbine 20c Variable nozzle mechanism 22 Intercooler 34 Reflux passage 38 Communication path 39. Shut-off valve 100 ECUs (Control Units)

Claims

1. An engine and motor capable of transmitting power to the drive wheels, A clutch that switches between an engaged state in which power from the engine can be transmitted to the drive wheel and a disengaged state in which power cannot be transmitted, while power from the motor can be transmitted to the drive wheel. A supercharger including a compressor and a turbine arranged in the intake passage and exhaust passage of the engine, respectively, and a variable nozzle mechanism that adjusts the flow velocity of the exhaust gas flowing into the turbine by the opening of the nozzle, An intercooler provided downstream of the compressor in the aforementioned intake passage, A recirculation passage that directs blow-by gas generated in the engine to the intake passage upstream of the compressor, A connecting passage having one end connected to the intake passage downstream of the compressor and upstream of the intercooler, and the other end connected to the return passage, A valve for opening and closing the aforementioned communication passage, A control device that controls the opening degree of the nozzle by the variable nozzle mechanism and opens the on / off valve so that intake air is supercharged by the compressor when the clutch is in the disengaged state, the motor is driving the vehicle, and the engine is running, A hybrid vehicle equipped with [a specific feature / ability].

2. The hybrid vehicle according to claim 1, wherein one end of the connecting passage is closer to the compressor than to the intercooler.

3. The hybrid vehicle according to claim 2, wherein the control device controls the opening of the nozzle to the minimum value when the clutch is disengaged, the vehicle is being driven by the motor, and the engine is running.

Images