Hybrid vehicle control device

Abstract

To clear freezing in a blow-by gas treatment device when moisture in blow-by gas condenses and freezes, thereby preventing the blockage of the blow-by gas treatment device, and to prevent engine damage caused by an abnormal increase in the internal pressure of a crankcase when the blow-by gas treatment device becomes blocked due to freezing.SOLUTION: In HEV-CU 80, in a state where the outside temperature is at or below a predetermined temperature, when an engine 10 is operated after EV driving with a second motor generator 12, if the internal pressure of a crankcase rises to a first threshold or higher, it is determined that a blow-by gas treatment device 160 is frozen and then the engine 10 is prohibited from stopping. Thereafter, if the internal pressure of the crankcase rises to a level at or above a second threshold, which is higher than the first threshold, it is determined that the blow-by gas treatment device 160 is blocked due to freezing, and the engine 10 is stopped, switching the driving mode to EV driving with the second motor generator 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle, and more particularly to a control device for a hybrid vehicle that is provided with an engine having a blow-by gas treatment device and an electric motor as drive sources. [Background technology]

[0002] In recent years, hybrid electric vehicles (HEVs) that can effectively improve the fuel consumption rate (fuel economy) of a vehicle by using both an engine and an electric motor (motor generator) have been widely put to practical use. In addition, some HEVs have been put to practical use, enabling EV driving in which the engine is stopped and the vehicle runs only on the electric motor for long periods of time and at high vehicle speeds, for example, by increasing the motor output and battery capacity.

[0003] Meanwhile, in order to prevent blow-by gas that has leaked out from between the cylinders and pistons of the engine into the crankcase from being released into the environment (atmosphere), blow-by gas treatment devices have been widely used that return the blow-by gas to the engine's intake system and combust it for treatment (see, for example, Patent Document 1).

[0004] The blow-by gas treatment device (blow-by circuit) is composed of, for example, a scavenging line that connects the inside of the crankcase with the downstream side of the throttle valve and returns (introduces) the blow-by gas to the intake system, a flow control valve (PCV (Positive Crankcase Ventilation) valve) that adjusts the flow rate of the blow-by gas flowing through the scavenging line, and a fresh air line that connects the upstream side of the throttle valve with the inside of the crankcase and introduces fresh air. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-173548 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in an extremely low temperature environment, for example, the blow-by gas containing moisture is cooled by the cold air (fresh air) from the outside, and the moisture in the blow-by gas condenses and freezes to form ice. The ice may then clog the scavenging line or the fresh air line, causing an abnormal increase in the pressure inside the crankcase.

[0007] In particular, in an extremely low temperature environment of, for example, -20°C or less, if the engine is stopped and the vehicle is driven in EV mode (at high vehicle speeds) using only the electric motor after driving for a short time using the engine (while it is running), the cooling of the blow-by gas treatment device (scavenging line, fresh air line, and flow control valve (PCV valve)) is accelerated (i.e., the cooling of the blow-by gas therein progresses), and the moisture in the blow-by gas condenses and becomes more likely to freeze. If the freezing of the blow-by gas treatment device (scavenging line, fresh air line, and / or flow control valve (PCV valve)) progresses and becomes completely blocked, the pressure inside the crankcase will abnormally increase, which may lead to damage to the engine.

[0008] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a control device for a hybrid vehicle that has an engine with a blow-by gas treatment device and an electric motor as drive sources, and that, when the moisture in the blow-by gas condenses and freezes, causing the blow-by gas treatment device to freeze, can thaw the device and prevent it from becoming clogged, and, when the blow-by gas treatment device becomes clogged due to freezing, can prevent damage to the engine due to an abnormal increase in internal pressure in the crankcase. [Means for solving the problem]

[0009] A control device for a hybrid vehicle according to one aspect of the present invention is a control device for a hybrid vehicle equipped with an engine having a blow-by gas treatment device including a scavenging line communicating between a crankcase and a downstream side of a throttle valve in an intake system for returning blow-by gas to the intake system, a fresh air line communicating between the upstream side of the throttle valve in the intake system and the crankcase for introducing fresh air, and a flow control valve interposed in the scavenging line for adjusting the flow rate of the blow-by gas according to the pressure in the intake system, and an electric motor as a drive source, the control device comprising: an outside air temperature sensor for detecting an outside air temperature; a pressure sensor attached to the fresh air line for detecting an internal pressure of the crankcase of the engine; and a control unit for controlling the drive of the engine and the electric motor, When the control unit stops the engine and starts the engine from EV driving, in which the vehicle runs only on the electric motor, in a situation where the outside air temperature detected by the outside air temperature sensor is below a predetermined temperature, if the crankcase internal pressure detected by the pressure sensor rises to or above a first threshold value, it determines that the scavenging line, fresh air line, and / or flow control valve that constitute the blow-by gas treatment device are frozen and prohibits the engine from being stopped, and if the crankcase internal pressure then rises to or above a second threshold value that is higher than the first threshold value, it determines that the scavenging line, fresh air line, and / or flow control valve that constitute the blow-by gas treatment device are blocked due to freezing, stops the engine, and switches to EV driving using the electric motor.

[0010] According to a control device for a hybrid vehicle according to one aspect of the present invention, when the outside air temperature is below a predetermined temperature, and the engine is started from EV driving, in which the engine is stopped and the vehicle is driven only by the electric motor, if the crankcase pressure rises to or above a first threshold value, it is determined that the scavenging line, the fresh air line, and / or the flow control valve constituting the blow-by gas treatment device are frozen, and the engine is prohibited from being stopped. Therefore, the blow-by gas treatment device can be unfrozen by the heat of the engine. Furthermore, if the crankcase pressure subsequently rises to or above a second threshold value higher than the first threshold value, it is determined that the scavenging line, the fresh air line, and / or the flow control valve constituting the blow-by gas treatment device are blocked due to freezing, and the engine is stopped and switched to EV driving by the electric motor. Therefore, it is possible to prevent damage to the engine due to an abnormal rise in the crankcase pressure. Effect of the Invention

[0011] According to the present invention, when the moisture in the blow-by gas condenses and freezes, causing the blow-by gas treatment device to freeze, the freezing can be thawed to prevent the blow-by gas treatment device from becoming clogged, and when the blow-by gas treatment device becomes clogged due to freezing, it is possible to prevent damage to the engine due to an abnormal increase in internal pressure in the crankcase. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a control device for a hybrid vehicle according to an embodiment, and a hybrid vehicle to which the control device is applied; [Diagram 2] 1 is a diagram showing a configuration of an engine having a blow-by gas treatment device mounted on a hybrid vehicle according to an embodiment; [Diagram 3] 4 is a flowchart showing a procedure of a freeze-thawing process of a blow-by gas treatment device and a process of preventing engine damage, which are performed by a control device for a hybrid vehicle according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, unless otherwise necessary, the same reference numerals will be used for the same or corresponding parts in the drawings. In addition, the same reference numerals will be used for the same elements in each drawing, and duplicated explanations will be omitted.

[0014] First, the configuration of a control device for a hybrid vehicle according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a diagram showing the configuration of a control device for a hybrid vehicle and a hybrid vehicle to which the control device is applied. Fig. 2 is a diagram showing the configuration of an engine 10 having a blow-by gas treatment device 160 mounted on the hybrid vehicle. Note that, here, the hybrid vehicle control device will be described taking as an example a case where it is mounted on a series-parallel hybrid vehicle (HEV).

[0015] First, the configuration of a hybrid vehicle will be described with reference to Fig. 1. A power split mechanism 30 is connected to a crankshaft 10a of an engine 10 (details of which will be described later) via a flywheel damper 20 that absorbs rotational fluctuations of the engine 10 and a pair of gears 21. A drive train 15 that is composed of a plurality of gears, shafts, etc. and transmits torque between the drive wheels, and a first motor-generator (MG) 11 (corresponding to an electric motor in the claims) are connected to the power split mechanism 30. The power split mechanism 30 has a planetary gear mechanism composed of, for example, a sun gear 30a, a ring gear 30b, a pinion gear 30c, and a planetary carrier 30d, and splits and transmits the drive torque generated by the engine 10 to the drive train 15 and the first motor-generator 11.

[0016] More specifically, the carrier 30d is connected to the crankshaft 10a of the engine 10 via the flywheel damper 20 and a pair of gears 21. The sun gear 30a is connected to the first motor-generator 11. Meanwhile, the ring gear 30b is connected to a propeller shaft 50 constituting the drive train 15 via a pair of gears (counter gears) 31, and is further connected to a front drive shaft 60 via a driving reduction gear 43.

[0017] When the first motor-generator 11 functions as a generator, the power distribution mechanism 30 distributes the torque (driving force) from the engine 10 input from the planetary carrier 30d to the sun gear 30a and the ring gear 30b according to the gear ratios of the two. On the other hand, when the first motor-generator 11 functions as a motor, the power distribution mechanism 30 integrates the torque from the engine 10 input from the planetary carrier 30d and the torque from the first motor-generator 11 input from the sun gear 30a, and outputs the integrated torque to the ring gear 30b. The torque output to the ring gear 30b is output to a propeller shaft 50 constituting the drive train 15 via a pair of gears (counter gears) 31, and is also output to a front drive shaft 60 via a drive reduction gear 43.

[0018] On the other hand, a second motor generator (MG) 12 (corresponding to an electric motor in the claims) is also connected to the drive train 15. More specifically, the second motor generator 12 is connected to a propeller shaft 50 via a motor reduction gear 41. The second motor generator 12 is also connected to a front drive shaft 60 via a drive reduction gear mechanism 40 composed of the motor reduction gear 41 and a drive reduction gear 43. The front drive shaft 60 transmits torque to the front wheels. The propeller shaft 50 transmits torque to the rear wheels.

[0019] The first motor-generator 11 and the second motor-generator 12 are configured as synchronous generator-motors that combine a function as a motor that converts supplied electric power into mechanical power and a function as a generator that converts input mechanical power into electric power. That is, the first motor-generator 11 and the second motor-generator 12 each operate as a motor that generates driving torque when driving the vehicle, and operate as a generator during regeneration. The first motor-generator 11 mainly operates as a generator, and the second motor-generator 12 mainly operates as a motor.

[0020] The driving reduction gear mechanism 40 is configured to include a motor reduction gear 41 and a driving reduction gear 43. The motor reduction gear 41 is configured from a planetary gear, and the reduction gear 43 is configured from, for example, a spur gear (or a helical gear).

[0021] More specifically, the motor reduction gear 41 has a planetary gear mechanism including, for example, a sun gear 41a, a ring gear 41b, a pinion gear 41c, and a planetary carrier 41d. When the second motor-generator 12 functions as a motor, the motor reduction gear 41 decelerates the rotation transmitted from the second motor-generator 12 (increases the torque) and outputs it from the planetary carrier 41d. On the other hand, the motor reduction gear 41 accelerates the rotation due to the torque (driving force) input to the planetary carrier 41d (reduces the torque) and outputs it from the sun gear 41a, thereby causing the second motor-generator 12 to function as a generator.

[0022] The front drive shaft 60 transmits torque between the driving reduction gear mechanism 40 and the driving wheels (front wheels in the example of FIG. 1). More specifically, the torque transmitted to the front drive shaft 60 is transmitted to a front differential (hereinafter also referred to as "front diff") 62. The front diff 62 is, for example, a bevel gear type differential device. The torque from the front diff 62 is transmitted to a left front wheel (not shown) via a left front wheel drive shaft, and is also transmitted to a right front wheel (not shown) via a right front wheel drive shaft.

[0023] On the other hand, the propeller shaft 50 transmits torque to the rear wheels. A transfer clutch 51 is interposed in the propeller shaft 50 to adjust the torque transmitted to the rear wheels. The transfer clutch 51 controls the fastening force (i.e., the torque distribution rate to the rear wheels) according to the drive state of the four wheels (for example, the slip state of the front wheels) and the engine torque. Therefore, the torque transmitted to the propeller shaft 50 is distributed according to the fastening force of the transfer clutch 51, and is also transmitted to the rear wheels.

[0024] More specifically, the torque transmitted to the propeller shaft 50 and adjusted (distributed) by the transfer clutch 51 is transmitted to a rear differential (hereinafter also referred to as "rear diff") 52. A left rear wheel drive shaft and a right rear wheel drive shaft (not shown) are connected to the rear differential 52. The driving force from the rear differential 52 is transmitted to the left rear wheel (not shown) via the left rear wheel drive shaft, and is also transmitted to the right rear wheel (not shown) via the right rear wheel drive shaft.

[0025] As configured in this manner, in the vehicle according to this embodiment (AWD HEV vehicle), the front and rear wheels (vehicle) can be driven by the power of the engine 10 and the second motor-generator 12, etc. Also, depending on the driving conditions, it is possible to switch between driving only by the second motor-generator 12 (EV driving) and driving by the engine 10 and the second motor-generator 12, etc. Furthermore, it is also possible to generate electricity (regenerate) by the first motor-generator 11, etc.

[0026] The engine 10, which is the driving force source of the vehicle, and the second motor-generator 12 and first motor-generator 11 are comprehensively controlled by a hybrid vehicle control unit (hereinafter referred to as “HEV-CU”) 80.

[0027] HEV-CU80 is composed of a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as the calculation results, a backup RAM in which the stored contents are retained, and an input / output I / F, etc.

[0028] The HEV-CU 80 is connected to various sensors, including an accelerator sensor 91 that detects the amount of depression of the accelerator pedal, i.e., the operation amount of the accelerator pedal, an outside air temperature sensor 93 that detects the outside air temperature (air temperature outside the vehicle), a rotation speed sensor 95 that detects the rotation speed of the front drive shaft 60, a resolver 97 that detects the rotation speed (rotation speed) of the first motor-generator 11, and a resolver 98 that detects the rotation speed (rotation speed) of the second motor-generator 12. As the outside air temperature sensor 93, for example, a thermistor whose resistance value changes according to temperature can be used. In addition, the HEV-CU 80 is also connected to a pressure sensor 164 that is attached to the fresh air line 163 and detects the pressure of the fresh air line 163, that is, the internal pressure of the crankcase 10b of the engine 10. As the pressure sensor 164, for example, a known sensor that outputs an electric signal (for example, a voltage) according to pressure can be used.

[0029] The HEV-CU 80 is also connected to an engine control unit (hereinafter referred to as "ECU") 81 that controls the engine 10, a vehicle dynamics control unit (hereinafter referred to as "VDCU") 85 that improves driving stability by suppressing vehicle skids, etc., via a CAN (Controller Area Network) 70 so as to be able to communicate with each other. The HEV-CU 80 receives various information, such as engine speed and brake operation amount, from the ECU 81 and the VDCU 85 via the CAN 70. Meanwhile, the HEV-CU 80 transmits various information, such as the speed (rotational speed) of the first motor-generator 11, the speed (rotational speed) of the second motor-generator 12, and accelerator operation amount, to the ECU 81 via the CAN 70.

[0030] Based on the various types of information acquired, the HEV-CU 80 comprehensively controls the driving of the engine 10, the second motor-generator 12, and the first motor-generator 11. The HEV-CU 80 determines and outputs the required output of the engine 10, stop prohibition / permission information (details will be described later), and torque command values ​​(target motor torque) for the second motor-generator 12 and the first motor-generator 11 based on, for example, the accelerator operation amount (drive force required by the driver), the driving state of the vehicle, the charging rate (SOC: State Of Charge) of the high-voltage battery 90 (corresponding to the storage battery in the claims), and the like.

[0031] A power control unit (hereinafter referred to as "PCU") 82 drives the second motor generator 12 and the first motor generator 11 via an inverter 82a based on the torque command value. The PCU 82 has an inverter 82a that converts DC power from a high-voltage battery 90 into three-phase AC power and supplies it to the second motor generator 12 and the first motor generator 11. As described above, the PCU 82 drives the second motor generator 12 and the first motor generator 11 via the inverter 82a based on the torque command value received from the HEV-CU 80. On the other hand, during regeneration, the inverter 82a converts the AC voltage generated by the first motor generator 11 and the second motor generator 12 into a DC voltage to charge the high-voltage battery 90.

[0032] Furthermore, the ECU 81 adjusts, for example, the opening of the electronically controlled throttle valve 113 based on the required output.

[0033] Next, the configuration of the engine 10 mounted on the hybrid vehicle will be described in detail with reference to FIG.

[0034] The engine 10 may be of any type, for example a horizontally opposed four-cylinder gasoline engine. The engine 10 is an in-cylinder injection engine that directly injects fuel into the cylinders. In the engine 10, air taken in through an air cleaner 116 is throttled by an electronically controlled throttle valve (hereinafter also simply referred to as a "throttle valve") 113 provided in an intake pipe 115, passes through an intake manifold 111, and is taken into each cylinder formed in the engine 10. The intake pipe 115 and the intake manifold 111 correspond to an intake system described in the claims.

[0035] The amount of air sucked in through air cleaner 116 is detected by an air flow meter 114 disposed between air cleaner 116 and throttle valve 113. A vacuum sensor (intake pressure sensor) 130 for detecting the pressure inside intake manifold 111 (intake manifold pressure) is disposed inside a collector section (surge tank) constituting intake manifold 111. Furthermore, a throttle sensor 131 for detecting the opening degree of throttle valve 113 is disposed in throttle valve 113.

[0036] An intake port 122 and an exhaust port 123 are formed in the cylinder head for each cylinder (only one bank is shown in FIG. 2). Each intake port 122 and exhaust port 123 is provided with an intake valve 124 and an exhaust valve 125 for opening and closing the intake port 122 and exhaust port 123, respectively. A variable valve timing mechanism 126 is disposed between the intake cam shaft that drives the intake valve 124 and the intake cam pulley, which rotates the intake cam pulley and the intake cam shaft relatively to continuously change the rotational phase (displacement angle) of the intake cam shaft with respect to the crankshaft 10a, thereby advancing or retarding the valve timing (opening / closing timing) of the intake valve 124. The variable valve timing mechanism 126 variably sets the opening and closing timing of the intake valve 124 according to the engine operating state.

[0037] Similarly, a variable valve timing mechanism 127 is disposed between the exhaust camshaft and the exhaust cam pulley, which rotates the exhaust cam pulley and the exhaust camshaft relatively to continuously change the rotational phase (displacement angle) of the exhaust camshaft with respect to the crankshaft 10a, thereby advancing or retarding the valve timing (opening / closing timing) of the exhaust valve 125. The variable valve timing mechanism 127 variably sets the opening / closing timing of the exhaust valve 125 according to the engine operating state.

[0038] An injector 112 that injects fuel into the cylinder is attached to each cylinder of the engine 10. The injector 112 directly injects fuel pressurized by a high-pressure fuel pump (not shown) into the combustion chamber of each cylinder.

[0039] Further, a spark plug 117 for igniting the air-fuel mixture and an igniter-integrated coil 121 for applying high voltage to the spark plug 117 are attached to the cylinder head of each cylinder. In each cylinder of the engine 10, the air-fuel mixture of the intake air and the fuel injected by the injector 112 is ignited by the spark plug 117 and combusted. Exhaust gas after combustion is discharged through an exhaust pipe 118.

[0040] An air-fuel ratio sensor 119 is attached downstream of the collecting portion of the exhaust pipe 118 and upstream of the exhaust purification catalyst 120. As the air-fuel ratio sensor 119, a linear air-fuel ratio sensor (LAF sensor) is used which can output a signal corresponding to the oxygen concentration and unburned gas concentration in the exhaust gas (i.e., a signal corresponding to the air-fuel ratio of the mixture) and can linearly detect the air-fuel ratio.

[0041] An exhaust purification catalyst 120 is disposed downstream of the LAF sensor 119. The exhaust purification catalyst 120 is a three-way catalyst that simultaneously oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx), purifying harmful gas components in the exhaust gas into harmless carbon dioxide (CO2), water vapor (H2O), and nitrogen (N2). A silencer (muffler) 143 that reduces exhaust noise is attached downstream of the exhaust purification catalyst 120.

[0042] An exhaust gas recirculation device (hereinafter referred to as an "EGR (Exhaust Gas Recirculation) device") 140 is provided in the exhaust pipe 118, which recirculates a portion of the exhaust gas discharged from the engine 10 to the intake manifold 111 of the engine 10. The EGR device 140 has an EGR pipe 141 that connects the exhaust pipe 118 of the engine 10 with the intake manifold 111, and an EGR valve 142 that is interposed on the EGR pipe 141 and adjusts the amount of exhaust gas recirculation (EGR flow rate). The opening degree (EGRSTP) of the EGR valve 142 is controlled by the ECU 81 according to the operating state of the engine 10.

[0043] In addition to the above-mentioned air flow meter 114, LAF sensor 119, vacuum sensor 130, and throttle sensor 131, a cam angle sensor 132 for identifying the cylinder of engine 10 is attached near the camshaft of engine 10. Also, a crank angle sensor 133 for detecting the rotational position of crankshaft 10a is attached near the crankshaft 10a of engine 10. Here, a timing rotor 133a having, for example, 34 projections with two teeth missing formed at 10° intervals is attached to the end of crankshaft 10a, and crank angle sensor 133 detects the rotational position of crankshaft 10a by detecting the presence or absence of the projection of timing rotor 133a. As cam angle sensor 132 and crank angle sensor 133, for example, an electromagnetic pickup type sensor or the like is used.

[0044] These sensors are connected to the ECU 81. In addition, the ECU 81 is also connected to various sensors such as a water temperature sensor 134 that detects the temperature of the cooling water for the engine 10, an oil temperature sensor 135 that detects the temperature of the lubricating oil, and the like.

[0045] The ECU 81 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM in which the stored contents are held by a battery or the like, and an input / output I / F, etc. The ECU 81 also includes an injector driver that drives the injector 112, an output circuit that outputs an ignition signal, and a motor driver that drives the electric motor 113a that opens and closes the electronically controlled throttle valve 113, etc. The ECU 81 also receives information such as the required output of the engine 10, stop prohibition / permission information, the number of revolutions (rotational speed) of the first motor-generator 11, the number of revolutions (rotational speed) of the second motor-generator 12, and accelerator operation amount from the HEV-CU 80 via the CAN 70.

[0046] The ECU 81 identifies the cylinder from the output of the cam angle sensor 132, and determines the rotational angular velocity and engine speed from the output of the crank angle sensor 133. The ECU 81 also acquires various information such as the intake air amount, the intake pipe negative pressure, the air-fuel ratio of the mixture, and the water temperature and oil temperature of the engine 10 based on the detection signals input from the various sensors described above. The ECU 81 then controls the engine 10 by controlling the fuel injection amount, the ignition timing, and various devices such as the throttle valve 113 and the EGR valve 142 based on the required output of the engine 10 from the HEV-CU 80, stop prohibition / permission information, and the acquired various information.

[0047] The engine 10 also has a blow-by gas treatment device 160 that introduces blow-by gas leaking from the combustion chamber into the crankcase 10b through between the cylinder and the piston into the intake pipe 115 or the like (intake system) and combusts it. The blow-by gas treatment device 160 includes a scavenging line (PCV line) 161 that connects the inside of the crankcase 10b with the downstream side of the throttle valve 113 of the intake pipe 115 or the like and returns (introduces) the blow-by gas to the intake pipe 115 or the like, a PCV valve 162 (corresponding to a flow control valve in the claims) that is interposed in the scavenging line 161 and adjusts the flow rate of the blow-by gas flowing through the scavenging line 161 depending on the pressure of the intake pipe 115 or the like, and a fresh air line 163 that connects the upstream side of the throttle valve 113 with the inside of the crankcase 10b and introduces fresh air.

[0048] In this embodiment, the PCV valve 162 is of a type that operates according to the pressure difference between the crankcase 10b and the downstream side of the throttle valve 113 (eg, the intake manifold 111).

[0049] Incidentally, in an extremely low-temperature environment of, for example, -20°C or lower, the blow-by gas containing moisture is cooled by the cold external air (fresh air), and the moisture in the blow-by gas condenses and freezes to form ice. If the scavenging line 161 or the fresh air line 163 is blocked by the ice, an abnormal increase in the pressure inside the crankcase may occur.

[0050] In particular, in an extremely low-temperature environment of, for example, -20°C or less, when the engine 10 is stopped and the vehicle runs in EV mode using only the second motor-generator 12, the cooling of the blow-by gas treatment device 160 (the scavenging line 161, the fresh air line 163, and the PCV valve 162) is accelerated (i.e., the cooling of the blow-by gas therein progresses), and the moisture in the blow-by gas becomes more likely to condense and freeze. If the freezing of the blow-by gas treatment device 160 (the scavenging line 161, the fresh air line 163, and / or the PCV valve 162) progresses and becomes completely blocked, the pressure inside the crankcase will abnormally increase, which may lead to damage to the engine 10.

[0051] Therefore, the above-mentioned HEV-CU80 has a function of preventing the blow-by gas processing device 160 from being blocked by unfreezing it when moisture in the blow-by gas condenses and freezes, and the blow-by gas processing device 160 freezes (when there is a possibility of blockage due to ice), and of preventing the engine 10 from being damaged (damaged) by an abnormal increase in the crankcase internal pressure when the blow-by gas processing device 160 is blocked due to freezing. That is, the HEV-CU80 functions as a control unit described in the claims. Note that the HEV-CU80 realizes this function by executing a program stored in an EEPROM or the like by a microprocessor.

[0052] Therefore, when the engine 10 is stopped and the engine 10 is started from EV driving in which the engine 10 is driven only by the second motor-generator 12 under a condition where the outside air temperature detected by the outside air temperature sensor 93 is below a predetermined temperature (e.g., -20°C), if the crankcase internal pressure detected by the pressure sensor 164 rises above a first threshold value (with hysteresis), the HEV-CU 80 determines that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are frozen (are becoming clogged or may become clogged by ice), and prohibits the engine 10 from being stopped (prohibits EV driving). Then, the blow-by gas treatment device 160 (the scavenging line 161, the fresh air line 163, and / or the PCV valve 162) is unfrozen (the ice is melted) by the heat of the engine 10.

[0053] In addition, in order to extend the driving distance in EV driving in the event that the engine 10 is stopped and forced to switch to EV driving due to the blow-by gas treatment device 160 subsequently freezing and becoming blocked (to prepare for a situation in which the engine 10 is forced to switch to EV driving), it is preferable that the HEV-CU 80 regenerates the first motor-generator 11 and charges the high-voltage battery 90 when the crankcase internal pressure rises above the first threshold value and stopping of the engine 10 is prohibited.

[0054] If the crankcase pressure subsequently rises to or exceeds a second threshold (with hysteresis) higher than the first threshold, the HEV-CU 80 determines that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are completely blocked due to freezing, stops the engine 10, and switches to EV driving using the second motor-generator 12. This prevents damage to the engine 10 due to an abnormal rise in crankcase pressure.

[0055] The second threshold value is set, for example, taking into consideration the upper limit and safety factor of the hardware of the engine 10. When the crankcase internal pressure rises to or exceeds the second threshold value and the engine 10 is rendered inoperable, for example, a warning light may be turned on to notify the driver of this.

[0056] Furthermore, in order to more reliably determine whether the blow-by gas treatment device 160 has frozen, the HEV-CU 80 prohibits the engine 10 from stopping until a predetermined time (e.g., about one minute) has elapsed, even if the crankcase internal pressure does not rise above the first threshold value after the engine 10 is operated (started) from EV driving.

[0057] On the other hand, when a predetermined time (e.g., about one minute) has elapsed without the crankcase internal pressure rising above the first threshold value after the engine 10 has been operated (started) from EV driving, the HEV-CU 80 switches to normal control that permits the engine 10 to be stopped. That is, the HEV-CU 80 determines that the blow-by gas treatment device 160 has not frozen, and switches to normal control that permits the engine 10 to be stopped (permits EV driving).

[0058] Furthermore, when the crankcase internal pressure rises above the first threshold value after operating (starting) the engine 10 from EV driving and then falls below the first threshold value without rising above the second threshold value, the HEV-CU 80 switches to normal control that permits the engine 10 to be stopped. That is, the HEV-CU 80 determines that the blow-by gas treatment device 160 has been unfrozen without being blocked, and switches to normal control that permits the engine 10 to be stopped (permits EV driving).

[0059] Next, the operation of the control device for the hybrid vehicle will be described with reference to Fig. 3. Fig. 3 is a flow chart showing the procedure of the freeze-thawing process of the blow-by gas treatment device 160 and the engine damage prevention process performed by the control device for the hybrid vehicle. This process is mainly executed repeatedly at a predetermined timing in the HEV-CU 80.

[0060] In step S100, a determination is made as to whether the outside air temperature is equal to or lower than a predetermined temperature (for example, -20°C). If the outside air temperature is equal to or lower than the predetermined temperature, the process proceeds to step S102. On the other hand, if the outside air temperature is higher than the predetermined temperature, the process is temporarily terminated.

[0061] In step S102, it is determined whether the engine 10 has been operated (started) from EV running, in which the engine 10 is stopped and the vehicle runs only on the second motor / generator 12. If the engine 10 has been operated (started), the process proceeds to step S104. On the other hand, if the engine 10 has not been operated (started), the process temporarily exits.

[0062] In step S104, stopping of the engine 10 is prohibited. Next, in step S106, it is determined whether the crankcase pressure of the engine 10 has risen to or above a first threshold value (with hysteresis). If the crankcase pressure has risen to or above the first threshold value, the process proceeds to step S110. On the other hand, if the crankcase pressure has not risen to or above the first threshold value, the process proceeds to step S108.

[0063] In step S108, a determination is made as to whether or not a predetermined time (for example, about one minute) has elapsed after the engine 10 has been operated (started) from EV driving. If the predetermined time has not elapsed, the process proceeds to step S104, and the above-described processes from step S104 onwards are repeatedly executed. On the other hand, if the predetermined time has elapsed, it is determined that the blow-by gas processing device 160 has not frozen, and in step S114, the process switches to normal control in which stopping of the engine 10 is permitted (EV driving is permitted). Then, the process ends.

[0064] In step S110, it is determined that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are frozen (are becoming clogged or may become clogged due to ice), and stopping of the engine 10 is prohibited. Then, regeneration is performed by the first motor-generator 11, and the high-voltage battery 90 is charged.

[0065] Next, in step S112, it is determined whether the crankcase pressure has fallen below the first threshold value. If the crankcase pressure has fallen below the first threshold value, it is determined that the blow-by gas processing device 160 has been unfrozen without being blocked, and the process proceeds to step S114. On the other hand, if the crankcase pressure has not fallen below the first threshold value, the process proceeds to step S116.

[0066] In step S114, the engine 10 is permitted to be stopped (EV driving is permitted), and control is switched to normal control. After that, the process exits from this process.

[0067] In step S116, it is determined whether the crankcase pressure of the engine 10 has risen to or above a second threshold value (with hysteresis) that is higher than the first threshold value. If the crankcase pressure has risen to or above the second threshold value, the process proceeds to step S118. On the other hand, if the crankcase pressure has not risen to or above the second threshold value, the process proceeds to step S110, and the processes from step S110 onwards are repeatedly executed.

[0068] In step S118, it is determined that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are clogged due to freezing, and the engine 10 is stopped and switched to EV driving by the second motor-generator 12. Then, this process is terminated.

[0069] As described above in detail, according to this embodiment, when the engine 10 is operated (started) from EV running in which the engine 10 is stopped and runs only on the second motor-generator 12 in a situation where the outside air temperature is below a predetermined temperature (for example, -20°C), if the crankcase internal pressure rises to or above the first threshold value, it is determined that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are frozen (are becoming clogged or may become clogged by ice), and the engine 10 is prohibited from stopping (EV running is prohibited). Therefore, the blow-by gas treatment device 160 can be unfrozen by the heat of the engine 10. Furthermore, if the crankcase internal pressure subsequently rises to or above the second threshold value higher than the first threshold value, it is determined that the scavenging line 161, the fresh air line 163, and / or the PCV valve 162 constituting the blow-by gas treatment device 160 are completely clogged due to freezing, and the engine 10 is stopped and switched to EV running by the second motor-generator 12. Therefore, damage to the engine 10 due to an abnormal increase in the pressure inside the crankcase can be prevented.

[0070] As a result, if the moisture in the blow-by gas condenses and freezes, causing the blow-by gas treatment device 160 to freeze, the freezing can be thawed to prevent the blow-by gas treatment device 160 from becoming clogged, and if the blow-by gas treatment device 160 becomes clogged due to freezing, it is possible to prevent damage to the engine 10 due to an abnormal increase in internal pressure in the crankcase.

[0071] According to this embodiment, even if the crankcase internal pressure does not rise to or exceed the first threshold value after the engine 10 is operated (started) from EV driving, the engine 10 is prohibited from being stopped until a predetermined time (for example, about one minute) has elapsed. Therefore, it is possible to more reliably determine whether the blow-by gas treatment device 160 is frozen or not.

[0072] According to this embodiment, after the engine 10 is operated (started) from EV driving, if a predetermined time (for example, about one minute) has elapsed without the crankcase internal pressure rising to or exceeding the first threshold value, the control is switched to normal control that permits the engine 10 to be stopped. Therefore, if it is determined that the blow-by gas treatment device 160 has not frozen, the control can be switched to normal control that permits the engine 10 to be stopped (EV driving).

[0073] According to this embodiment, after the engine 10 is operated (started) from EV running, if the crankcase internal pressure increases to or exceeds the first threshold value and then falls below the first threshold value without increasing to or exceeds the second threshold value, control is switched to normal control that permits stopping of the engine 10. Therefore, if it is determined that the freezing of the blow-by gas treatment device 160 has been resolved without causing blockage, control can be switched to normal control that permits stopping of the engine 10 (EV running).

[0074] According to this embodiment, when the crankcase internal pressure rises to or exceeds the first threshold value and stopping of the engine 10 is prohibited, regeneration is performed by the first motor-generator 11 to charge the high-voltage battery 90. Therefore, if the engine 10 is subsequently stopped and forced to switch to EV driving due to the blow-by gas treatment device 160 freezing and clogging, the driving distance in EV driving can be extended (i.e., preparation can be made assuming a case where the engine 10 is forced to switch to EV driving).

[0075] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the control device according to the present invention is applied to a series-parallel hybrid vehicle (HEV), but the control device can be applied to a different type of hybrid vehicle (for example, a parallel hybrid vehicle or a series hybrid vehicle) or a plug-in hybrid vehicle (PHEV) that can be charged from an external source. In addition, in the above embodiment, two electric motors (the first motor generator 11 and the second motor generator 12) are provided, but the number of electric motors is not limited to two (two motors), and may be one (one motor), or three (three motors) or more. Similarly, the configuration of a drive system or the like that is composed of a plurality of gears and shafts is not limited to the above embodiment.

[0076] Furthermore, the system configuration of the controllers such as the HEV-CU 80 and the ECU 81, and the functional division of each controller are not limited to the above embodiment. For example, the ECU 81 may be configured to read the crankcase internal pressure, determine whether the blow-by gas treatment device 160 is frozen or blocked, and transmit the determination result to the HEV-CU 80.

[0077] In the above embodiment, the present invention is applied to a naturally aspirated (NA) engine, but the present invention can also be applied to an engine equipped with a supercharger (turbocharger, etc.). Furthermore, in the above embodiment, the present invention is applied to an AWD vehicle (all-wheel drive vehicle), but the present invention can also be applied to, for example, a 2WD vehicle (FF vehicle or FR vehicle). [Explanation of symbols]

[0078] 10 Engine 10b Crankcase 11 First motor generator 12 Second motor generator 20 Flywheel damper 30 Driving force split mechanism 40 Driving reduction gear mechanism 41 Motor reduction gear 43 Driving reduction gear 50 Propeller shaft 51 Transfer clutch 52 Rear differential 60 Front drive shaft 62 Front differential 70 CAN 80 HEV-CU 81 ECU 82 PCU 85 VDCU 90 High voltage battery (storage battery) 91 Accelerator Sensor 93 Outside Air Temperature Sensor 95 RPM Sensor 97,98 Resolver 111 Intake manifold 112 Injector 113 Electronically controlled throttle valve 114 Air flow meter 115 Intake pipe 117 Spark Plug 118 Exhaust pipe 119 Air-fuel ratio sensor 120 Exhaust purification catalyst 130 Vacuum sensor (intake pressure sensor) 131 Throttle sensor 133 Crank angle sensor 133a Timing rotor 134 Water temperature sensor 140 Exhaust Gas Recirculation System 141 EGR piping 142 EGR valve 143 Silencer 160 Blow-by gas treatment device 161 Scavenging line 162 PCV valve 163 New Air Line 164 Pressure Sensor

Claims

1. A control device for a hybrid vehicle equipped with an engine having a blow-by gas treatment device including a scavenging line communicating a crankcase with a downstream side of a throttle valve of an intake system and returning blow-by gas to the intake system, a fresh air line communicating an upstream side of a throttle valve of the intake system with the crankcase and introducing fresh air, and a flow control valve interposed in the scavenging line and adjusting a flow rate of the blow-by gas in accordance with a pressure of the intake system, and an electric motor as a drive source, An outside air temperature sensor for detecting an outside air temperature; a pressure sensor attached to the fresh air line and capable of detecting an internal pressure of a crankcase of the engine; a control unit that controls the drive of the engine and the electric motor, The control unit includes: in a situation where the outside air temperature detected by the outside air temperature sensor is equal to or lower than a predetermined temperature, when the engine is stopped and the engine is started from EV driving in which the vehicle is driven only by the electric motor, if the crankcase internal pressure detected by the pressure sensor rises to or above a first threshold value, it is determined that a scavenging line, a fresh air line, and / or a flow control valve constituting the blow-by gas treatment device are frozen, and stopping of the engine is prohibited; Thereafter, when the crankcase internal pressure rises to or above a second threshold value higher than the first threshold value, it is determined that the scavenging line, the fresh air line, and / or the flow control valve constituting the blow-by gas treatment device are clogged due to freezing, and the engine is stopped and the vehicle is switched to EV driving using the electric motor. A control device for a hybrid vehicle.

2. 2. The control device for a hybrid vehicle according to claim 1, wherein the control unit prohibits stopping of the engine until a predetermined time has elapsed, even if the crankcase internal pressure does not rise above the first threshold value after the engine is started from EV driving.

3. 3. The control device for a hybrid vehicle according to claim 2, wherein the control unit switches to normal control to permit stopping of the engine when the predetermined time has elapsed without the crankcase internal pressure increasing above the first threshold value after the engine is started from EV driving.

4. 4. The control device for a hybrid vehicle according to claim 3, wherein the control unit switches to normal control that permits stopping of the engine when, after the engine is started from EV driving and the crankcase internal pressure rises to or above the first threshold value and then falls to less than the first threshold value without rising to or above the second threshold value.

5. 5. The control device for a hybrid vehicle according to claim 4, wherein the control unit, when the crankcase internal pressure rises to or exceeds the first threshold value and the engine is prohibited from being stopped, causes the electric motor to regenerate power and charges a storage battery that supplies power to the electric motor.

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