Hybrid vehicles

Abstract

To make opening / closing timing of a suction valve more appropriate when rapid catalyst warming-up control is executed.SOLUTION: When catalyst warming-up control for warming up a catalyst of a purifier is executed by operation during delaying ignition timing, idle operation of an engine is instructed, a variable valve timing mechanism is controlled so that opening / closing timing of a suction valve becomes first predetermined target valve timing. By using the first predetermined target valve timing as the opening / closing timing of the suction valve suitable for performing catalyst warming-up while performing the idle operation, the opening / closing timing of the suction valve when catalyst warming-up control is executed during idle-on can be made more appropriate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle equipped with a first electric motor capable of generating electricity mechanically connected to the output shaft of an engine equipped with a variable valve timing mechanism, and a second electric motor capable of inputting and outputting power for driving. [Background technology]

[0002] As a conventional technique of this type, a hybrid vehicle has been proposed in which a purification device having a catalyst for purifying exhaust gas is attached to the exhaust system and the engine has a variable valve timing mechanism that can change the opening and closing timing of the intake valve (see, for example, Patent Document 1). In this hybrid vehicle, when a request to warm up the purification catalyst is made and the running power is greater than the power equivalent to the output limit, if the degree of catalyst warm-up has not reached a predetermined level, the engine is controlled to open and close the intake valve at an earlier timing than after the degree of catalyst warm-up has reached the predetermined level. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-071664 Summary of the Invention [Problem to be solved by the invention]

[0004] When warming up the catalyst in the purification device, it is desirable to complete the catalyst warm-up quickly, so it is desirable to change the engine operation depending on the state of the hybrid vehicle. When the engine is in a state where idling is commanded and torque output from the engine is not required, the engine operation state can be made suitable for rapid catalyst warm-up. On the other hand, when the engine is not in a state where idling is commanded and torque output from the engine is required, it is necessary to achieve both torque output from the engine and catalyst warm-up. In an engine equipped with a variable valve timing mechanism, the intake valve opening and closing timing is also one of the engine operating states, so it is desirable to maintain appropriate opening and closing timing even during catalyst warm-up.

[0005] A primary object of the hybrid vehicle of the present invention is to provide a more appropriate timing for opening and closing the intake valve when catalyst warm-up control is executed. [Means for solving the problem]

[0006] The hybrid vehicle of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The hybrid vehicle of the present invention is an engine having an exhaust system equipped with a purification device having a catalyst for purifying exhaust gas, a variable valve timing mechanism capable of changing the opening and closing timing of an intake valve, and a direct injection valve; a first electric motor mechanically connected to an output shaft of the engine and capable of generating electricity; a second electric motor capable of inputting and outputting power for running; an electricity storage device capable of exchanging electric power with the first electric motor and the second electric motor; a control device that controls the engine, the first electric motor, and the second electric motor; A hybrid vehicle comprising: When executing rapid catalyst warm-up control for warming up the catalyst of the purification device by operating the engine with a retarded ignition timing, if an idle operation of the engine is instructed, the control device controls the variable valve timing mechanism so that the opening and closing timing of the intake valve becomes a first predetermined target valve timing. It is characterized by:

[0008] In the hybrid vehicle of the present invention, when rapid catalyst warm-up control is performed to warm up the catalyst of the purification device by operating the vehicle with retarded ignition timing, the variable valve timing mechanism is controlled so that the intake valve opening / closing timing becomes a first predetermined target valve timing when engine idle operation is instructed (idle on). When idle on, no torque is requested to the engine and the engine is controlled to idle at a predetermined rotation speed. Therefore, by setting the intake valve opening / closing timing (first predetermined target valve timing) appropriate for this, the intake valve opening / closing timing when catalyst warm-up control is performed during idle on can be made more appropriate. The first predetermined target valve timing can be determined by experimentation, machine learning, or the like.

[0009] In the hybrid vehicle of the present invention, when executing the catalyst warm-up control, if the engine is not instructed to idle, the control device may control the variable valve timing mechanism so that the intake valve opening / closing timing is set to a second predetermined target valve timing different from the first predetermined target valve timing. When catalyst warm-up is performed during idle-off, the engine may be set to output a predetermined torque (e.g., 20 Nm or 30 Nm) at a predetermined engine speed (e.g., 1100 rpm or 1300 rpm). Therefore, by setting the intake valve opening / closing timing (second predetermined target valve timing) appropriate for such engine operation, the intake valve opening / closing timing during catalyst warm-up control during idle-off can be more appropriate. The second predetermined target valve timing can be determined through experiments, machine learning, or the like, and is retarded from the first predetermined target valve timing.

[0010] In the hybrid vehicle of the present invention, when executing the catalyst warm-up control, the control device may control the variable valve timing mechanism so that the intake valve opening / closing timing is a third predetermined target valve timing when the engine is not instructed to idle, the engine is permitted to operate at a fixed point, or a torque demand value for the engine is less than a predetermined value. The third predetermined target valve timing is an opening / closing timing that allows torque output from the engine without changing the intake valve timing when the torque demand value for the engine is less than the predetermined value. This allows torque up to the torque demand value to be output from the engine while warming up the catalyst without changing the opening / closing timing of the intake valve. The third predetermined target valve timing may be the same as the second predetermined target valve timing, or may be slightly advanced or retarded from the second predetermined target valve timing. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the outline of the configuration of an engine 22. [Figure 3] FIG. 2 is a diagram showing the outline of the configuration of a variable valve timing mechanism 160. [Figure 4] FIG. 2 is a diagram showing the outline of the configuration of a variable valve timing mechanism 160. [Figure 5] 4 is a flowchart showing an example of normal catalyst warm-up control executed by an engine ECU 24. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0013] Fig. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to one embodiment of the present invention, and Fig. 2 is a diagram showing an outline of the configuration of an engine 22. As shown in Fig. 1, the hybrid vehicle 20 of the embodiment includes the engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and a hybrid electronic control unit (hereinafter referred to as HVECU) 70.

[0014] The engine 22 is configured as a six-cylinder internal combustion engine that uses fuel such as gasoline or diesel and outputs power through four strokes: intake, compression, expansion (explosive combustion), and exhaust. As shown in FIG. 2, the engine 22 has a port injection valve 126 that injects fuel supplied from a fuel supply device 150 via a low-pressure supply pipe 153 into an intake port, and an in-cylinder injection valve 127 that injects fuel supplied from the fuel supply device 150 via a high-pressure supply pipe 158 into a cylinder. The in-cylinder injection valve 127 is disposed approximately at the center of the top of a combustion chamber 129 and injects fuel in a spray form. The spark plug 130 is disposed near the in-cylinder injection valve 127 so that it can ignite the fuel sprayed from the in-cylinder injection valve 127 in a spray form. The port injection valve 126 and the in-cylinder injection valve 127 enable the engine 22 to operate in any of a port injection mode, an in-cylinder injection mode, and a common injection mode. In the port injection mode, air purified by an air cleaner 122 is drawn into an intake pipe 123 and passes through a throttle valve 124 and a surge tank 125. At the same time, fuel is injected from a port injection valve 126 downstream of the surge tank 125 in the intake pipe 123 to mix the air and fuel. This mixture is then drawn into a combustion chamber 129 via an intake valve 128 and is explosively combusted by an electric spark from an ignition plug 130. The reciprocating motion of a piston 132, which is pushed down within the cylinder bore by the energy of the fuel, is converted into rotational motion of the crankshaft 23. In the direct injection mode, as in the port injection mode, air is drawn into the combustion chamber 129, and fuel is injected from a direct injection valve 127 during the intake stroke or compression stroke. The fuel is explosively combusted by an electric spark from the ignition plug 130 to generate rotational motion of the crankshaft 23. In the common injection mode, fuel is injected from port injection valve 126 when air is drawn into combustion chamber 129, and fuel is injected from in-cylinder injection valve 127 during the intake stroke and compression stroke, and the fuel is explosively burned by an electric spark from spark plug 130, generating rotational motion of crankshaft 23. These injection modes are switched based on the operating state of engine 22. Exhaust gas discharged from combustion chamber 129 through exhaust valve 133 into exhaust pipe 134 is discharged into the outside air via purification device 135.The purification device 135 has a purification catalyst (three-way catalyst) 135a that purifies harmful components in the exhaust gas, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

[0015] The fuel supply device 150 is configured as a device that supplies fuel in a fuel tank 151 to the port injection valves 126 and the in-cylinder injection valves 127 of the engine 22. The fuel supply device 150 includes the fuel tank 151, a feed pump 152, a low-pressure supply pipe 153, a check valve 154, a relief pipe 155, a relief valve 156, a high-pressure pump 157, and a high-pressure supply pipe 158.

[0016] Feed pump 152 is configured as an electric pump that operates by receiving power from a battery (not shown), and is disposed in fuel tank 151. Feed pump 152 supplies fuel from fuel tank 151 to low-pressure supply pipe 153. Low-pressure supply pipe 153 is connected to port injection valve 126. Check valve 154 is provided in low-pressure supply pipe 153, and allows fuel to flow in the direction from feed pump 152 to port injection valve 126, while restricting fuel flow in the opposite direction.

[0017] Relief pipe 155 is connected to low-pressure supply pipe 153 and fuel tank 151. Relief valve 156 is provided in relief pipe 155, and closes when the fuel pressure in low-pressure supply pipe 153 is below threshold Pflolim, and opens when the fuel pressure in low-pressure supply pipe 153 is equal to or higher than threshold Pflolim. When relief valve 156 opens, some of the fuel in low-pressure supply pipe 153 is returned to fuel tank 151 via relief pipe 155. In this way, the fuel pressure in low-pressure supply pipe 153 is prevented from becoming excessive.

[0018] High-pressure pump 157 is driven by power from engine 22 (in this embodiment, the rotation of intake camshaft 119, which opens and closes intake valve 128), and is configured as a pump that pressurizes fuel in low-pressure supply pipe 153 and supplies it to high-pressure supply pipe 158. High-pressure pump 157 has an electromagnetic valve 157a connected to its intake port that opens and closes when pressurizing the fuel, a check valve 157b connected to its discharge port that regulates backflow of fuel and maintains the fuel pressure in high-pressure supply pipe 158, and a plunger 157c that is actuated (moves in the vertical direction in FIG. 1 ) by the rotation of engine 22 (the rotation of intake camshaft 119). When the electromagnetic valve 157a is opened while the engine 22 is running, the high-pressure pump 157 draws in fuel from the low-pressure supply pipe 153, and when the electromagnetic valve 157a is closed, the high-pressure pump 157 pressurizes the fuel to be supplied to the high-pressure supply pipe 158 by intermittently sending the fuel compressed by the plunger 157c to the high-pressure supply pipe 158 via the check valve 157b.

[0019] The engine 22 also includes a variable valve timing mechanism 160 on the intake camshaft 119 that can continuously change the opening and closing timing VT (opening timing VToin and closing timing VTcin) of the intake valve 128 while maintaining the operating angle (the angle between the opening timing VToin and the closing timing VTcin). Figures 3 and 4 are diagrams showing an outline of the configuration of the variable valve timing mechanism 160.

[0020] As shown in the figure, variable valve timing mechanism 160 includes a vane-type VVT ​​controller 162, a vane position sensor 163, and an oil control valve 166. VVT controller 162 is composed of a housing portion 162a, a vane portion 162b, and an assist spring (not shown). Housing portion 162a is fixed to a timing gear 174 connected to the crankshaft 23 of each bank via a timing chain 172. Vane portion 162b is fixed to intake camshaft 119, which opens and closes intake valve 128. Both ends of the assist spring are attached to housing portion 162a and vane portion 162b, respectively, and urges vane portion 162b in the advance direction. Vane position sensor 163 detects the position of vane portion 162b. The oil control valve 166 is configured as a well-known oil control valve having a sleeve, a spool valve, a linear solenoid, a plunger, etc., and operates (the spool valve moves) in response to the current supplied from a current adjustment unit (not shown) to apply oil pressure to the advance side oil chamber and the retard side oil chamber of the VVT ​​controller 162.

[0021] In variable valve timing mechanism 160, vane portion 162b is rotated relative to housing portion 162a by adjusting the hydraulic pressure acting on the advance-side oil chamber and the retard-side oil chamber of VVT controller 162 via oil control valve 166. This continuously changes the angle of intake camshaft 119 at the opening / closing timing VT of intake valve 128. In this embodiment, the angle of intake camshaft 119 corresponding to the opening / closing timing VT of intake valve 128 that allows efficient power output from engine 22 is set as a reference angle. By advancing the angle of intake camshaft 119 from the reference angle, an operating state in which high torque can be output from engine 22 can be achieved. Furthermore, by setting the angle of intake camshaft 119 to a predetermined angle on the retard side (e.g., the most retarded angle), pressure fluctuations within the cylinders of engine 22 can be reduced, resulting in an operating state suitable for stopping and starting engine 22.

[0022] The operation of the engine 22 is controlled by an engine ECU 24. The engine ECU 24 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, although these are not shown.

[0023] Signals from various sensors required for controlling the operation of the engine 22 are input via an input port to the engine ECU 24. Examples of signals input to the engine ECU 24 include a crank angle θcr from a crank position sensor 140 that detects the rotational position of a crankshaft 23 of the engine 22, and a coolant temperature Tw from a water temperature sensor 142 that detects the temperature of the coolant for the engine 22. Other examples of signals input to the engine ECU 24 include cam angles θci and θco from a cam position sensor 144 that detects the rotational position of an intake camshaft 119 that opens and closes intake valves 128 and the rotational position of an exhaust camshaft that opens and closes exhaust valves 133. Other examples include a throttle opening TH from a throttle valve position sensor 124a that detects the position of the throttle valve 124, an intake air amount Qa from an air flow meter 123a attached upstream of the throttle valve 124 in the intake pipe 123, an intake air temperature Ta from a temperature sensor 123t attached upstream of the throttle valve 124 in the intake pipe 123, and a surge pressure Ps from a pressure sensor 125a attached to the surge tank 125. Other examples include a front air-fuel ratio AF1 from a front air-fuel ratio sensor 137 attached upstream of the purification device 135 in the exhaust pipe 134, and a rear air-fuel ratio AF2 from a rear air-fuel ratio sensor 138 attached between the purification device 135 and the PM filter 136 in the exhaust pipe 134. Other examples include the fuel temperature Tftnk from a fuel temperature sensor 151t attached to the fuel tank 151, the rotation speed Np of the feed pump 152 from a rotation speed sensor 152a attached to the feed pump 152, the low-pressure fuel pressure (the pressure of the fuel supplied to the port injection valve 126) PL from a fuel pressure sensor 153p attached to the low-pressure supply pipe 153 near the port injection valve 126 (e.g., a low-pressure delivery pipe), and the high-pressure fuel pressure (the pressure of the fuel supplied to the in-cylinder injection valve 127) PH from a fuel pressure sensor 158p attached to the high-pressure supply pipe 158 near the in-cylinder injection valve 127 (e.g., a high-pressure delivery pipe).

[0024] The engine ECU 24 outputs various control signals via an output port for controlling the operation of the engine 22. Examples of signals output from the engine ECU 24 include a control signal to the throttle valve 124, a control signal to the port injection valve 126, a control signal to the in-cylinder injection valve 127, a control signal to the spark plug 130, and a control signal to a variable valve timing mechanism 160 that can change the opening and closing timing of the intake valve 128. Other examples of signals output from the engine ECU 24 include a control signal to the feed pump 152 of the fuel supply device 150 and a control signal to the electromagnetic valve 157a of the high-pressure pump 157.

[0025] The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the engine 22 from the crank position sensor 140. The engine ECU 24 also calculates the load factor KL (the ratio of the volume of air actually taken in during one cycle to the stroke volume per cycle of the engine 22) based on the intake air amount Qa from the air flow meter 123a and the rotation speed Ne of the engine 22.

[0026] As shown in Fig. 1, the planetary gear 30 is configured as a single-pinion planetary gear mechanism. A rotor of a motor MG1 is connected to a sun gear of the planetary gear 30. A drive shaft 36, which is coupled to drive wheels 39a, 39b via a differential gear 38, is connected to a ring gear of the planetary gear 30. A crankshaft 23 of the engine 22 is connected to a carrier of the planetary gear 30.

[0027] The motor MG1 is configured as, for example, a synchronous generator motor, and as described above, its rotor is connected to the sun gear of the planetary gear 30. The motor MG2 is configured as, for example, a synchronous generator motor, and its rotor is connected to the drive shaft 36. The inverters 41 and 42 are used to drive the motors MG1 and MG2, and are connected to a battery 50 via a power line 54. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40, which controls the switching of a plurality of switching elements (not shown) of the inverters 41 and 42.

[0028] The motor ECU 40 includes a microcomputer (not shown) having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors required for driving and controlling the motors MG1 and MG2 are input to the motor ECU 40 via the input port. Examples of signals input to the motor ECU 40 include rotational positions θm1 and θm2 from rotational position sensors (not shown) that detect the rotational positions of the rotors of the motors MG1 and MG2, and phase currents Iu1, Iv1, Iu2, and Iv2 from current sensors (not shown) that detect the phase currents flowing through the phases of the motors MG1 and MG2. The motor ECU 40 outputs switching control signals and other signals to multiple switching elements (not shown) of the inverters 41 and 42 via the output port. The motor ECU 40 is connected to the HVECU 70 via the communication port. The motor ECU 40 calculates the electrical angles θe1, θe2 and rotation speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position sensors.

[0029] Battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery, and as described above, is connected to inverters 41, 42 via power line 54. Battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0030] The battery ECU 52 includes a microcomputer (not shown) having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors required for managing the battery 50 are input to the battery ECU 52 via an input port. Examples of signals input to the battery ECU 52 include the voltage Vb of the battery 50 from a voltage sensor (not shown) attached between the terminals of the battery 50, the current Ib of the battery 50 from a current sensor (not shown) attached to the output terminals of the battery 50, and the temperature Tb of the battery 50 from a temperature sensor (not shown) attached to the battery 50. The battery ECU 52 is connected to the HVECU 70 via a communication port. The battery ECU 52 calculates the state of charge (SOC) of the battery 50 based on the integrated value of the current Ib of the battery 50 from the current sensor. The state of charge (SOC) is the ratio of the amount of power that can be discharged from the battery 50 to the total capacity of the battery 50.

[0031] Although not shown, the HVECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the HVECU 70 via the input ports. Examples of signals input to the HVECU 70 include an ignition signal from an ignition switch 80 and a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81. Other examples of signals input to the HVECU 70 include an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication ports.

[0032] In the hybrid vehicle 20 of the embodiment configured in this manner, cooperative control between the HVECU 70, engine ECU 24, and motor ECU 40 basically switches between a hybrid driving mode (HV driving mode) in which the vehicle runs with the engine 22 operating, and an electric driving mode (EV driving mode) in which the vehicle runs without the engine 22 operating, and the vehicle runs while operating the engine 22 intermittently.

[0033] In the HV driving mode, the HVECU 70 basically first sets a driving torque Td* required for driving (required of the drive shaft 36) based on the accelerator opening Acc and the vehicle speed V, and then calculates a driving power Pd* required for driving by multiplying the set driving torque Td* by the rotation speed Nd of the drive shaft 36 (the rotation speed Nm2 of the motor MG2). Next, the HVECU 70 sets a target power Pe* for the engine 22 based on the driving power Pd* and the power storage percentage SOC of the battery 50, and sets a target rotation speed Ne* and target torque Te* for the engine 22 and torque commands Tm1* and Tm2* for the motors MG1 and MG2 so that the target power Pe* is output from the engine 22 and the driving torque Td* is output to the drive shaft 36. The set target rotation speed Ne* and target torque Te* are sent to the engine ECU 24, and the torque commands Tm1* and Tm2* are sent to the motor ECU 40.

[0034] The engine ECU 24 performs operation control of the engine 22, such as intake air amount control, fuel injection control, ignition control, and opening / closing timing control, so that the engine 22 operates based on the target rotation speed Ne* and target torque Te*. The intake air amount control is performed by controlling the opening of the throttle valve 124. The fuel injection control is performed by controlling the fuel injection amount from the port injection valve 126 and the in-cylinder injection valve 127 in the port injection mode, the in-cylinder injection mode, or the shared injection mode. The ignition control is performed by controlling the ignition timing of the spark plug 130. The motor ECU 40 performs switching control of multiple switching elements of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1* and Tm2*.

[0035] In the EV driving mode, the HVECU 70 sets the driving torque Td* in the same manner as in the HV driving mode, sets the torque command Tm1* of the motor MG1 to the value 0, and sets the torque command Tm2* of the motor MG2 so that the driving torque Td* is output to the drive shaft 36. The set torque commands Tm1* and Tm2* are sent to the motor ECU 40. The control of the inverters 41 and 42 by the motor ECU 40 has been described above.

[0036] In the HV driving mode, when the target power Pe* falls below the power threshold Peref, it is determined that the stop condition for the engine 22 is met, and the engine 22 is stopped and the driving mode is switched to the EV driving mode. In the EV driving mode, when the target power Pe* calculated in the same way as in the HV driving mode falls above the power threshold (Peref+α), it is determined that the start condition for the engine 22 is met, and the engine 22 is started and the driving mode is switched to the HV driving mode.

[0037] In the hybrid vehicle 20 of the embodiment, catalyst warm-up is performed on the purification catalyst (three-way catalyst) 135a of the purification device 135 attached to the exhaust pipe 134 of the engine 22. The catalyst warm-up of the purification device 135 is performed when the condition that the catalyst temperature Tc is equal to or lower than a predetermined temperature below the activation temperature or when the accelerator is released is met. There are two types of catalyst warm-up: normal catalyst warm-up and rapid catalyst warm-up. The normal catalyst warm-up is performed by maintaining the engine 22 rotation speed Ne at a predetermined rotation speed Nset (e.g., 1300 rpm), injecting fuel from the in-cylinder injection valve 127 one to three times during the intake stroke to homogenize the mixture in the combustion chamber 129, and setting the ignition timing to near the base ignition timing, which is retarded from the normal timing, to perform explosive combustion (homogeneous combustion). Rapid catalyst warm-up is achieved by maintaining engine speed Ne at a predetermined speed Nset (e.g., 1300 rpm), injecting fuel from in-cylinder injection valve 127 not only during the intake stroke but also during the compression stroke, thereby increasing the fuel concentration of the air-fuel mixture in combustion chamber 129 near spark plug 130, and then setting the ignition timing to near the base ignition timing further retarded from the base ignition timing for normal catalyst warm-up, thereby performing explosive combustion (stratified charge combustion). Since retarding the ignition timing reduces combustion efficiency, the intake air amount is increased to maintain engine speed Ne. However, the increased amount of combustion gas increases the absolute amount of emissions, but promotes catalyst warm-up. Therefore, rapid catalyst warm-up can further promote catalyst warm-up by further retarding the ignition timing compared to normal catalyst warm-up. In addition, with rapid catalyst warm-up, fuel is injected one to three times during the intake stroke and compression stroke, and the final fuel injection is performed during the expansion stroke, and ignition is sometimes performed in synchronization with the fuel injection during this expansion stroke, resulting in explosive combustion (stratified combustion).

[0038] Next, the operation of the hybrid vehicle 20 of this embodiment configured as described above, particularly the operation when setting the opening and closing timing of the intake valve 128 during normal catalyst warm-up control, will be described. Figure 5 is a flowchart showing an example of normal catalyst warm-up control executed by the engine ECU 24.

[0039] When the normal catalyst warm-up control of FIG. 5 is executed, the engine ECU 24 first determines whether or not idle operation of the engine 22 has been instructed (idle-on or idle-off) (step S100). If it is determined that idle-on is instructed, the engine ECU 24 executes idle-on catalyst warm-up control so that the engine 22 operates autonomously (idle operation) at a predetermined engine speed Nset and sets the ignition timing Tp to a timing Tp1 that is significantly retarded from the timing Tp0 during normal idle operation (step S110). The target valve timing of the variable valve timing mechanism 160 is set to a first predetermined target valve timing (step S120), and the process ends. The first predetermined target valve timing can be determined by experimentation, machine learning, or the like to promote catalyst warm-up. In the idle-on catalyst warm-up control, the ignition timing Tp and the intake air amount Qa are feedback-controlled so that the engine speed Ne of the engine 22 becomes the predetermined engine speed Nset.

[0040] If it is determined in step S100 that the engine 22 is in the idle-off state, the process determines whether fixed-point operation of the engine 22 is permitted and whether the torque required for the engine 22 is less than a predetermined value (step S130). If it is determined that fixed-point operation of the engine 22 is not permitted and the torque required for the engine 22 is equal to or greater than the predetermined value, catalyst warm-up control for the idle-off state is executed (step S140) so that the engine 22 outputs a predetermined torque Tset (e.g., 20 Nm or 30 Nm) at a predetermined engine speed Nset and the ignition timing Tp is set to a timing Tp2 that is slightly advanced from the timing Tp1 during idle-on. The process then ends. The target valve timing of the variable valve timing mechanism 160 is set to a second predetermined target valve timing (step S150). The second predetermined target valve timing can be determined by experimentation, machine learning, or the like so as to promote catalyst warm-up while outputting the predetermined torque Tset from the engine 22, and is more retarded than the first predetermined target valve timing.

[0041] If it is determined in step S130 that fixed-point operation of the engine 22 is permitted or that the torque request value for the engine 22 is less than a predetermined value, the process executes predetermined catalyst warm-up control for idle-off so that the engine 22 outputs a predetermined torque Tset (e.g., 20 Nm or 30 Nm) at a predetermined rotational speed Nset and sets the ignition timing Tp to a timing Tp3 that is slightly retarded from the timing Tp1 during idle-on (step S160). The process then ends. The third predetermined target valve timing is used to enable the engine 22 to output torque up to the predetermined torque Tset as driving torque during catalyst warm-up. If catalyst warm-up is interrupted (the ignition timing Tp is advanced), the engine 22 can output torque up to a certain value (greater than the predetermined torque Tset) as driving torque without changing the opening / closing timing. Therefore, although rapid catalyst warm-up is switched between execution and suspension in response to torque requests to the engine 22 up to a certain torque, it is possible to respond without changing the opening / closing timing of the intake valve 128. The third predetermined target valve timing may be the same as or different from the second predetermined target valve timing. In this embodiment, since the second predetermined target valve timing is used for catalyst warm-up control during idle off, the same timing as the second predetermined target valve timing is used as the third predetermined target valve timing in consideration of its continuity.

[0042] In the hybrid vehicle 20 of the embodiment described above, when catalyst warm-up is performed during idle on, the first predetermined target valve timing is set as the opening / closing timing of the intake valve 128. This makes it possible to make the opening / closing timing of the intake valve 128 more appropriate when catalyst warm-up control is performed during idle on.

[0043] Furthermore, in the hybrid vehicle 20 of the embodiment, when catalyst warm-up is performed during idle off, a second predetermined target valve timing different from the first predetermined target valve timing during idle on is set as the opening / closing timing of the intake valve 128. This makes it possible to more appropriately set the opening / closing timing of the intake valve 128 when catalyst warm-up control is performed during idle off.

[0044] In the hybrid vehicle 20 of the embodiment, when it is determined that fixed-point operation of the engine 22 is permitted during idle-off or that the torque request value for the engine 22 is less than a predetermined value, a third predetermined target valve timing (same as the second predetermined target valve timing in the embodiment) is set as the opening / closing timing for the intake valve 128. This allows for a torque request for the engine 22 up to a certain torque greater than the predetermined torque Tset to be accommodated without changing the opening / closing timing of the intake valve 128, although catalyst warm-up is switched between execution and suspension.

[0045] In the hybrid vehicle 20 of the embodiment, when it is determined that fixed-point operation of the engine 22 is permitted during idle-off or that the torque demand value for the engine 22 is less than a predetermined value, the third predetermined target valve timing, which is the same as the second predetermined target valve timing, is set as the opening / closing timing of the intake valve 128, just as when rapid catalyst warm-up is performed during idle-off. However, the third predetermined target valve timing may be different from the second predetermined target valve timing. In this case, the third predetermined target valve timing may be more advanced or more retarded than the second predetermined target valve timing.

[0046] In the hybrid vehicle 20 of the embodiment, the engine 22 used is one in which the in-cylinder injection valve 127 is arranged approximately in the center of the top of the combustion chamber 129, but it is also possible to use an engine in which the in-cylinder injection valve 127 is arranged on the side wall (side) of the combustion chamber 129.

[0047] In the hybrid vehicle 20 of the embodiment, the engine 22 is equipped with the port injection valve 126 and the in-cylinder injection valve 127, but an engine equipped with only the in-cylinder injection valve without the port injection valve may also be used.

[0048] In the hybrid vehicle 20 of the embodiment, the battery 50 is used as the power storage device, but any device capable of storing power may be used, such as a capacitor.

[0049] The hybrid vehicle 20 of the embodiment includes the engine ECU 24, the motor ECU 40, the battery ECU 52, and the HVECU 70, but at least two of these may be configured as a single electronic control unit.

[0050] In the embodiment, the present invention has been described as being applied to a hybrid vehicle 20 that includes an engine 22, motors MG1 and MG2, and a planetary gear 30. However, the hybrid vehicle may have any configuration as long as it includes an engine, a first motor that is mechanically connected to the output shaft of the engine and is capable of generating electricity, and a second motor that is capable of inputting and outputting power for running.

[0051] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the purification device 135 corresponds to the "purification device," the engine 22 corresponds to the "engine," the motor MG1 corresponds to the "first electric motor," the motor MG2 corresponds to the "second electric motor," the battery 50 corresponds to the "electricity storage device," and the engine ECU 24, the motor ECU 40, and the HVECU 70 correspond to the "control device."

[0052] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0053] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0054] The present invention can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0055] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 24 Engine ECU, 30 Planetary gear, 36 Drive shaft, 38 Differential gear, 39a, 39b Drive wheels, 40 Motor ECU, 41, 42 Inverter, 50 Battery, 52 Battery ECU, 54 Power line, 70 HVECU, 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 87 Vehicle speed sensor, 119 Intake camshaft, 122 Air cleaner, 123 Intake pipe, 123a Air flow meter, 123t Temperature sensor, 124 Throttle valve, 124a Throttle valve position sensor, 125 Surge tank, 125a Pressure sensor, 126 Port injection valve, 127 In-cylinder injection valve, 128 intake valve, 129 combustion chamber, 130 spark plug, 132 piston, 133 exhaust valve, 134 exhaust pipe, 135 purification device, 135a purification catalyst, 136 PM filter, 136a differential pressure sensor, 137 front air-fuel ratio sensor, 138 rear air-fuel ratio sensor, 140 crank position sensor, 142 water temperature sensor, 144 cam position sensor, 150 fuel supply device, 151 fuel tank, 151t fuel temperature sensor, 152 feed pump, 152a rotation speed sensor, 153 low-pressure supply pipe, 153p fuel pressure sensor, 154 check valve, 155 relief pipe, 156 relief valve, 157 high-pressure pump, 157a solenoid valve, 157b check valve, 157c plunger, 158 high-pressure supply pipe, 158p Fuel pressure sensor, 160 variable valve timing mechanism, 162 VVT controller, 162a housing part, 162b vane part, 163 vane position sensor, 166 oil control valve, 172 timing chain, 174 timing gear, MG1, MG2 motors.

Claims

1. an engine having an exhaust system equipped with a purification device having a catalyst for purifying exhaust gas, a variable valve timing mechanism capable of changing the opening and closing timing of an intake valve, and a direct injection valve; a first electric motor mechanically connected to an output shaft of the engine and capable of generating electricity; a second electric motor capable of inputting and outputting power for running; an electric storage device capable of exchanging electric power with the first electric motor and the second electric motor; a control device that controls the engine, the first electric motor, and the second electric motor; A hybrid vehicle comprising: The control device When executing catalyst warm-up control for warming up the catalyst of the purification device by operating the engine with a retarded ignition timing, if an idle operation of the engine is instructed, the engine is controlled so that the engine idles at a predetermined rotation speed, and the variable valve timing mechanism is controlled so that the opening and closing timing of the intake valve becomes a first predetermined target valve timing; When the catalyst warm-up control is executed and an idle operation of the engine is not instructed, the engine is controlled so as to output a predetermined torque at the predetermined rotation speed, and the variable valve timing mechanism is controlled so that the opening and closing timing of the intake valve becomes a second predetermined target valve timing that is retarded from the first predetermined target valve timing. Hybrid car.

2. The hybrid vehicle according to claim 1, When executing the catalyst warm-up control, if an idle operation of the engine is not instructed, a fixed-point operation of the engine is permitted, or a torque request value for the engine is less than a predetermined value, the control device controls the variable valve timing mechanism so that the opening / closing timing of the intake valve becomes a third predetermined target valve timing. Hybrid car.

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