Hybrid vehicles

Abstract

To more appropriately determine combustion deterioration of an engine during execution of rapid catalyst warming-up control and more appropriately perform the rapid catalyst warming-up control.SOLUTION: During execution of rapid catalyst warming-up control for warming up a catalyst of a purification device by operating an engine at predetermined speed by injecting fuel in a compression stroke or an expansion stroke and delaying ignition timing, in the case where an idling operation of the engine is instructed, combustion deterioration of the engine is determined when engine speed becomes lower than predetermined speed by a speed threshold value or greater, and in the case where the idling operation of the engine is not instructed, the combustion deterioration of the engine is determined when engine torque estimated from output torque of a first electric motor becomes lower than predetermined torque by a torque threshold value or greater.SELECTED DRAWING: Figure 3

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 an output shaft of an engine, and a second electric motor capable of inputting and outputting power for running. [Background technology]

[0002] A conventional technique of this type has been proposed in which fuel is injected during the compression stroke to rapidly warm up the catalyst of a purification device attached to the exhaust system of the engine, and the ignition timing is significantly delayed (see, for example, Patent Document 1). In this type of rapid catalyst warm-up, the amount of intake air and the ignition timing are also adjusted so that the engine speed becomes a predetermined speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-32318 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned rapid catalyst warm-up, it is desirable to interrupt the rapid catalyst warm-up when the engine speed falls below a certain level from a predetermined speed, because the engine combustion deteriorates. However, in a hybrid vehicle equipped with a first electric motor capable of generating electricity mechanically connected to the output shaft of the engine and a second electric motor capable of inputting and outputting power for running, the first electric motor supports the engine speed so that it does not fall below a predetermined speed even if the engine combustion deteriorates. In this case, if the rapid catalyst warm-up is continued, the torque output by the first electric motor causes the battery to discharge, and the battery's charge storage rate decreases.

[0005] A primary object of the hybrid vehicle of the present invention is to more appropriately determine deterioration of engine combustion while rapid catalyst warm-up control is being executed, and to more appropriately execute rapid catalyst warm-up control. [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 in-cylinder injection valve and a purification device having a catalyst for purifying exhaust gas attached to an exhaust system; 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 traveling; 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: The control device, while executing a rapid catalyst warm-up control for warming up a catalyst of the purification device by operating the engine at a predetermined revolution speed and performing fuel injection during a compression stroke or an expansion stroke and by retarding an ignition timing, When an idle operation of the engine is instructed, a deterioration in combustion of the engine is determined when a rotation speed of the engine falls below the predetermined rotation speed by an amount equal to or greater than a rotation speed threshold value; When an idle operation of the engine is not instructed, a deterioration in combustion of the engine is determined when a torque of the engine estimated from an output torque of the first electric motor falls below a predetermined torque by an amount equal to or greater than a torque threshold value. It is characterized by:

[0008] In the hybrid vehicle of the present invention, when the engine is instructed to idle during the execution of the rapid catalyst warm-up control, which warms up the catalyst of the purification device by operating the engine at a predetermined rotation speed by injecting fuel during the compression stroke or expansion stroke and retarding the ignition timing, the deterioration of engine combustion is determined when the engine rotation speed falls below the predetermined rotation speed by more than the rotation speed threshold value. When the engine is instructed to idle (idle on), the engine rotation speed is controlled by the fuel injection amount and ignition timing to be the predetermined rotation speed. Therefore, when the engine rotation speed falls below the predetermined rotation speed by more than the rotation speed threshold value even with this control, it is determined that the deterioration of engine combustion is too great to continue the rapid catalyst warm-up control. In this case, it is preferable to interrupt the rapid catalyst warm-up control. When the engine is not instructed to idle during the execution of the rapid catalyst warm-up control, the deterioration of engine combustion is determined when the engine torque estimated from the output torque of the first electric motor falls below the predetermined torque by more than the torque threshold value. When the engine idle operation is not instructed (when the engine is in the idle off state), the engine speed is controlled by the first motor so that it becomes a predetermined speed. Therefore, even if the engine output torque becomes small, the engine speed is maintained at the predetermined speed. Therefore, when the engine torque estimated from the output torque of the first motor falls below the predetermined torque by a torque threshold value or more, the engine combustion deterioration is determined. In the case of the engine combustion deterioration, the output torque of the first motor increases in order to maintain the engine speed, and the battery discharge power also increases, so that it becomes necessary to suppress the increase in the battery discharge power. In this case, it is preferable to interrupt the rapid catalyst warm-up control. That is, in the hybrid vehicle of the present invention, when the engine idle operation is instructed, the engine combustion deterioration is determined based on the engine speed, and when the engine idle operation is not instructed, the engine combustion deterioration is determined based on the engine torque estimated from the output torque of the first motor. This makes it possible to more appropriately determine the engine combustion deterioration during the execution of the rapid catalyst warm-up control.Furthermore, when engine combustion deteriorates, the rapid catalyst warm-up control can be interrupted, for example, so that the rapid catalyst warm-up control can be performed more appropriately.

[0009] In the hybrid vehicle of the present invention, the control device may interrupt the rapid catalyst warm-up control when it is determined that the engine combustion has deteriorated while the rapid catalyst warm-up control is being executed. That is, when an idle operation of the engine is instructed, it may determine to interrupt the rapid catalyst warm-up control based on the engine speed, and when an idle operation of the engine is not instructed, it may determine to interrupt the rapid catalyst warm-up control based on the engine torque estimated from the output torque of the first electric motor. This makes it possible to more appropriately determine to interrupt the rapid catalyst warm-up control.

[0010] In the hybrid vehicle of the present invention, the control device may determine the improvement of the engine combustion deterioration when the engine speed reaches or exceeds the predetermined speed or a return speed that is greater than the predetermined speed minus the speed threshold value when idling of the engine is instructed during the interruption of the rapid catalyst warm-up control, and determine the improvement of the engine combustion deterioration when the engine torque estimated from the output torque of the first electric motor reaches or exceeds the predetermined torque or a return torque that is greater than the predetermined torque minus the torque threshold value when idling of the engine is not instructed. Since the determination of the improvement of the engine combustion deterioration is similar to the determination of the engine combustion deterioration, the improvement of the engine combustion deterioration can be more appropriately determined by determining the improvement of the engine combustion deterioration based on the engine speed when idling of the engine is instructed, and determining the improvement of the engine combustion deterioration based on the engine torque estimated from the output torque of the first electric motor when idling of the engine is not instructed. In this case, the control device may be configured to resume the rapid catalyst warm-up control when it determines that the deterioration of combustion in the engine has improved while the rapid catalyst warm-up control is suspended. In this way, the rapid catalyst warm-up control can be resumed more appropriately. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an outline of the configuration of an engine 22. [Diagram 3] 4 is a flowchart showing an example of a rapid catalyst warm-up control interruption process executed by an engine ECU 24. [Figure 4] 5 is a flowchart showing an example of a rapid catalyst warm-up control recovery process executed by an engine ECU 24. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0013] Fig. 1 is a schematic diagram showing the configuration of a hybrid vehicle 20 according to an embodiment of the present invention, and Fig. 2 is a schematic diagram showing 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 through 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 through 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 as to ignite the fuel sprayed in a spray form from the in-cylinder injection valve 127. The engine 22 has the port injection valve 126 and the in-cylinder injection valve 127, and can be operated in any one of a port injection mode, an in-cylinder injection mode, and a common injection mode. In the port injection mode, air purified by the air cleaner 122 is drawn into the intake pipe 123 and passes through the throttle valve 124 and the surge tank 125, while fuel is injected from the port injection valve 126 downstream of the surge tank 125 of the intake pipe 123 to mix the air and fuel. This mixture is then drawn into the combustion chamber 129 via the intake valve 128 and combusted explosively by an electric spark from the spark plug 130, and the reciprocating motion of the piston 132, which is pushed down by the energy of the mixture in the cylinder bore, is converted into the rotational motion of the crankshaft 23. In the in-cylinder injection mode, air is drawn into the combustion chamber 129 in the same manner as in the port injection mode, and fuel is injected from the in-cylinder injection valve 127 during the intake stroke and compression stroke, and the fuel is combusted explosively by an electric spark from the spark plug 130 to obtain the rotational motion of the crankshaft 23. In the common injection mode, fuel is injected from the port injection valve 126 when air is drawn into the combustion chamber 129, and fuel is injected from the in-cylinder injection valve 127 during the intake stroke and the compression stroke, and the fuel is exploded and burned by an electric spark from the spark plug 130 to obtain the rotational motion of the crankshaft 23. These injection modes are switched based on the operating state of the engine 22. Exhaust discharged from the combustion chamber 129 into the exhaust pipe 134 via the exhaust valve 133 is discharged into the outside air via a 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 a port injection valve 126 and an in-cylinder injection valve 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. This feed pump 152 supplies fuel in 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 regulating 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 value Pflolim, and opens when the fuel pressure in low-pressure supply pipe 153 is equal to or higher than threshold value Pflolim. When relief valve 156 opens, a portion 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] The high-pressure pump 157 is driven by power from the engine 22 (in this embodiment, the rotation of the intake camshaft that opens and closes the intake valve 128) and is configured as a pump that pressurizes fuel in the low-pressure supply pipe 153 and supplies it to the high-pressure supply pipe 158. The high-pressure pump 157 has an electromagnetic valve 157a connected to its intake port and opens and closes when pressurizing the fuel, a check valve 157b connected to its discharge port and restricts the backflow of fuel and maintains the fuel pressure in the high-pressure supply pipe 158, and a plunger 157c that is actuated (moves in the vertical direction in FIG. 1 ) by the rotation of the engine 22 (the rotation of the intake camshaft). When the engine 22 is operating, the high-pressure pump 157 draws in fuel from the low-pressure supply pipe 153 when the electromagnetic valve 157a is opened, 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 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 (not shown).

[0020] Signals from various sensors required for controlling the operation of the engine 22 are input to the engine ECU 24 via an input port. 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 the 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 that opens and closes the intake valve 128 and the rotational position of an exhaust camshaft that opens and closes the exhaust valve 133. Other examples of such a measurement include the throttle opening TH from a throttle valve position sensor 124a that detects the position of the throttle valve 124, the intake air amount Qa from an air flow meter 123a attached upstream of the throttle valve 124 in the intake pipe 123, the intake air temperature Ta from a temperature sensor 123t attached upstream of the throttle valve 124 in the intake pipe 123, and the surge pressure Ps from a pressure sensor 125a attached to the surge tank 125. Other examples of such a measurement 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 of such fuel pressure 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).

[0021] Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via an output port. 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 ignition plug 130, and a control signal to a variable valve timing mechanism 139 that can change the opening and closing timing of the intake valve 128. Other examples 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.

[0022] 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 a load factor KL (the ratio of the volume of air actually taken in 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.

[0023] As shown in Fig. 1, the planetary gear 30 is configured as a single pinion type planetary gear mechanism. A rotor of a motor MG1 is connected to a sun gear of the planetary gear 30. A drive shaft 36 that is connected 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.

[0024] The motor MG1 is configured, for example, as 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, for example, as a synchronous generator motor, and its rotor is connected to the drive shaft 36. The inverters 41, 42 are used to drive the motors MG1, MG2, and are connected to a battery 50 via a power line 54. The motors MG1, MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40 controlling the switching of a plurality of switching elements (not shown) of the inverters 41, 42.

[0025] The motor ECU 40 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors required for driving and controlling the motors MG1 and MG2 are input to the motor ECU 40 via the input ports. 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 the like to a plurality of switching elements (not shown) of the inverters 41 and 42 via the output ports. The motor ECU 40 is connected to the HVECU 70 via a 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.

[0026] The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery, and as described above, is connected to the inverters 41, 42 via the power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter referred to as the "battery ECU") 52.

[0027] Although not shown, the battery ECU 52 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. 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 a voltage Vb of the battery 50 from a voltage sensor (not shown) attached between the terminals of the battery 50, a current Ib of the battery 50 from a current sensor (not shown) attached to an output terminal of the battery 50, and a 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 a power storage ratio SOC of the battery 50 based on an integrated value of the current Ib of the battery 50 from the current sensor. The power storage ratio SOC is a ratio of the amount of power that can be discharged from the battery 50 to the total capacity of the battery 50.

[0028] Although not shown, the HVECU 70 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. Signals from various sensors are input to the HVECU 70 via the input port. 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 operation 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 port.

[0029] In the hybrid vehicle 20 of the embodiment thus configured, the HVECU 70, the engine ECU 24, and the motor ECU 40 are controlled in a coordinated manner to basically switch between a hybrid driving mode (HV driving mode) in which the engine 22 is operated, and an electric driving mode (EV driving mode) in which the engine 22 is not operated, and the vehicle runs while operating the engine 22 intermittently.

[0030] 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 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 (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 charge storage rate 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.

[0031] 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 the 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 a plurality of switching elements of the inverters 41, 42 so that the motors MG1, MG2 are driven by the torque commands Tm1*, Tm2*.

[0032] 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 a value of 0, sets the torque command Tm2* of the motor MG2 so that the driving torque Td* is output to the drive shaft 36, and transmits the set torque commands Tm1* and Tm2* to the motor ECU 40. The control of the inverters 41 and 42 by the motor ECU 40 has been described above.

[0033] 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 satisfied, and the engine 22 is stopped and the mode is switched to the EV driving mode. In the EV driving mode, when the target power Pe* calculated in the same manner 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 satisfied, and the engine 22 is started and the mode is switched to the HV driving mode.

[0034] 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 temperature at which the catalyst is activated or the accelerator is off is satisfied. 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 rotation speed Ne of the engine 22 at a predetermined rotation speed Nset (for example, 1300 rpm, etc.), injecting fuel from the in-cylinder injection valve 127 once to three times during the intake stroke to homogenize the mixture in the combustion chamber 129, and performing explosive combustion (homogeneous combustion) by setting the ignition timing to the vicinity of the base ignition timing, which is retarded from the normal timing. Rapid catalyst warm-up is performed by maintaining the rotation speed Ne of the engine 22 at a predetermined rotation speed Nset (for example, 1300 rpm, etc.), injecting fuel from the in-cylinder injection valve 127 during the intake stroke, as well as performing the final fuel injection during the compression stroke to increase the fuel concentration of the mixture in the combustion chamber 129 near the ignition plug 130, and performing explosive combustion (stratified combustion) with the ignition timing set to near the base ignition timing that is further retarded from the base ignition timing of normal catalyst warm-up. Since retarding the ignition timing reduces combustion efficiency, the amount of intake air is increased to maintain the rotation speed Ne of the engine 22, while the amount of combustion gas increases, which increases the absolute amount of emission components, 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. In some cases, the fuel is ignited in synchronization with the fuel injection during the expansion stroke, resulting in explosive combustion (stratified charge combustion).

[0035] Next, the operation of the hybrid vehicle 20 of the embodiment thus configured, particularly the operation when interrupting the rapid catalyst warm-up control and resuming the interrupted rapid catalyst warm-up control, will be described. Fig. 3 is a flowchart showing an example of a rapid catalyst warm-up control interruption process executed by the engine ECU 24, and Fig. 4 is a flowchart showing an example of a rapid catalyst warm-up control restoration process executed by the engine ECU 24. The rapid catalyst warm-up control interruption process of Fig. 3 is repeatedly executed while the rapid catalyst warm-up control is being executed, and the rapid catalyst warm-up control restoration process of Fig. 4 is repeatedly executed while the rapid catalyst warm-up control is interrupted by the rapid catalyst warm-up control interruption process of Fig. 3 and remains interrupted. The rapid catalyst warm-up control interruption process and the rapid catalyst warm-up control restoration process will be described below in order.

[0036] 3, the engine ECU 24 first determines whether or not idling of the engine 22 is instructed (idle on or idle off) (step S100). In the case of the rapid catalyst warm-up, when the engine 22 is in the idle on state, the engine 22 is controlled to operate autonomously at a predetermined rotation speed Nset. On the other hand, when the engine 22 is in the idle off state, the rapid catalyst warm-up is performed by controlling the rotation speed of the motor MG1 so that the rotation speed Ne of the engine 22 becomes the predetermined rotation speed Nset, and controlling the engine 22 so that a predetermined torque (e.g., 20 Nm or 30 Nm) Tset is output from the engine 22.

[0037] When it is determined in step S100 that the engine is in the idle-on state, the engine speed Ne of the engine 22 is input (step S110), and it is determined whether or not the engine speed Ne of the engine 22 is less than the predetermined engine speed Nset minus the engine speed threshold Nref, that is, whether or not the engine 22 is experiencing a deterioration in combustion (step S120). When it is determined that the engine speed Ne of the engine 22 is equal to or greater than the predetermined engine speed Nset minus the engine speed threshold Nref, it is determined that the engine 22 is experiencing a deterioration in combustion and that the rapid catalyst warm-up is being performed normally, and this process is terminated. On the other hand, when it is determined that the engine speed Ne of the engine 22 is less than the predetermined engine speed Nset minus the engine speed threshold Nref, it is determined that the engine 22 is experiencing a deterioration in combustion and that the rapid catalyst warm-up control may cause a misfire or the like of the engine 22 if the rapid catalyst warm-up control is continued, and the rapid catalyst warm-up control is interrupted (step S160), and this process is terminated. This makes it possible to prevent the engine 22 from experiencing a misfire or the like due to the rapid catalyst warm-up during the idle-on state.

[0038] When it is determined in step S100 that the engine is in the idle-off state, the torque Tm1 of the motor MG1 is input (step S130), and an estimated torque Teest that is estimated to be output from the engine 22 is estimated from the torque Tm1 of the motor MG1 (step S140). It is determined whether the estimated torque Teset is less than a torque obtained by subtracting a torque threshold value Tref from a predetermined torque Tset, that is, whether the combustion of the engine 22 is deteriorating (step S150). The torque Tm1 of the motor MG1 can use a torque command Tm1* of the motor MG1 set by the HVECU 70. The estimated torque Teest can be calculated from the gear ratio of the planetary gear 30 (number of teeth of the sun gear / number of teeth of the ring gear) and the torque Tm1 of the motor MG1. The predetermined torque Teset is set as the torque output from the engine 22 during rapid catalyst warm-up during the idle-off state. When it is determined that the estimated torque Teest is equal to or greater than the predetermined torque Tset minus the torque threshold Tref, it is determined that the combustion of the engine 22 has not deteriorated and that the rapid catalyst warm-up is being performed normally, and this process is terminated. On the other hand, when it is determined that the estimated torque Teest is less than the predetermined torque Tset minus the torque threshold Tref, it is determined that the combustion of the engine 22 has deteriorated and that if the rapid catalyst warm-up control is continued, the torque output from the motor MG1 will increase, causing the discharge power of the battery 50 to increase and the power storage percentage SOC of the battery 50 to decrease, and the rapid catalyst warm-up control is interrupted (step S160) and this process is terminated. This makes it possible to prevent the discharge power of the battery 50 from increasing and the power storage percentage SOC of the battery 50 from decreasing due to the rapid catalyst warm-up during idle off.

[0039] When the rapid catalyst warm-up control return process of FIG. 4 is executed, the engine ECU 24 first determines whether or not an idle operation of the engine 22 has been instructed (idle on or idle off) (step S200).

[0040] When it is determined in step S200 that the engine is in the idle-on state, the rotation speed Ne of the engine 22 is input (step S210), and it is determined whether or not the rotation speed Ne of the engine 22 is equal to or greater than a predetermined rotation speed Nset (step S220). When it is determined that the rotation speed Ne of the engine 22 is equal to or greater than the predetermined rotation speed Nset, it is determined that the deterioration of the combustion of the engine 22 has improved and rapid catalyst warm-up can be performed normally, and the rapid catalyst warm-up control is restored (step S260), and this process is terminated. On the other hand, when it is determined that the rotation speed Ne of the engine 22 is less than the predetermined rotation speed Nset, it is determined that the deterioration of the combustion of the engine 22 has not improved and rapid catalyst warm-up control should not be restored yet, and this process is terminated.

[0041] When it is determined in step S200 that the engine is in an idle-off state, the torque Tm1 of the motor MG1 is input (step S230), and an estimated torque Teest that is estimated to be output from the engine 22 is estimated from the torque Tm1 of the motor MG1 (step S240), and it is determined whether the estimated torque Teset is equal to or greater than a predetermined torque Tset (step S250). When it is determined that the estimated torque Teset is equal to or greater than the predetermined torque Tset, it is determined that the deterioration of the combustion of the engine 22 has improved and that rapid catalyst warm-up can be performed normally, and the rapid catalyst warm-up control is resumed (step S260), and this process is terminated. On the other hand, when it is determined that the estimated torque Teest is less than the predetermined torque Tset, it is determined that the deterioration of the combustion of the engine 22 has not improved and that the rapid catalyst warm-up control should not be resumed yet, and this process is terminated.

[0042] In the hybrid vehicle 20 of the embodiment described above, when the engine 22 is in the idle-on state while the rapid catalyst warm-up control is being executed, it is determined that the combustion of the engine 22 has deteriorated and the rapid catalyst warm-up control is interrupted when the rotation speed Ne of the engine 22 falls below the rotation speed obtained by subtracting the rotation speed threshold Nref from the predetermined rotation speed Nset. On the other hand, when the engine 22 is in the idle-off state while the rapid catalyst warm-up control is being executed, it is determined that the combustion of the engine 22 has deteriorated and the rapid catalyst warm-up control is interrupted when the estimated torque Teest estimated to be output from the engine 22 from the torque Tm1 of the motor MG1 falls below the torque obtained by subtracting the torque threshold Tref from the predetermined torque Tset. That is, by changing the method of determining the deterioration of the combustion of the engine 22 depending on whether the engine 22 is in the idle-on state or the idle-off state, it is possible to more appropriately determine the deterioration of the combustion of the engine 22 and more appropriately interrupt the rapid catalyst warm-up control. As a result, it is possible to more appropriately execute the rapid catalyst warm-up control.

[0043] In the hybrid vehicle 20 of the embodiment, when the engine 22 is in the idle-on state while the rapid catalyst warm-up control is suspended, the improvement of the deterioration of the combustion of the engine 22 is determined when the rotation speed Ne of the engine 22 reaches or exceeds a predetermined rotation speed Nset, and the rapid catalyst warm-up control is resumed. On the other hand, when the engine 22 is in the idle-off state while the rapid catalyst warm-up control is suspended, the improvement of the deterioration of the combustion of the engine 22 is determined when the estimated torque Teest estimated to be output from the engine 22 from the torque Tm1 of the motor MG1 reaches or exceeds a predetermined torque Tset, and the rapid catalyst warm-up control is resumed. That is, by changing the method of determining the improvement of the deterioration of the combustion of the engine 22 depending on whether the engine 22 is in the idle-on state or the idle-off state, the improvement of the deterioration of the combustion of the engine 22 can be more appropriately determined, and the rapid catalyst warm-up control can be more appropriately resumed. As a result, the rapid catalyst warm-up control can be more appropriately performed.

[0044] In the hybrid vehicle 20 of the embodiment, while the rapid catalyst warm-up control is interrupted, when the engine 22 is in an idle-on state, the rapid catalyst warm-up control is restored when the rotation speed Ne of the engine 22 reaches or exceeds a predetermined rotation speed Nset, and when the engine 22 is in an idle-off state, the rapid catalyst warm-up control is restored when the estimated torque Teest estimated to be output from the engine 22 from the torque Tm1 of the motor MG1 reaches or exceeds a predetermined torque Tset. However, when the engine 22 is in an idle-on state, the rapid catalyst warm-up control may be restored when the rotation speed Ne of the engine 22 reaches or exceeds a return rotation speed that is greater than the rotation speed obtained by subtracting a rotation speed threshold value Nref from the predetermined rotation speed Nset, and when the engine 22 is in an idle-off state, the rapid catalyst warm-up control may be restored when the estimated torque Teest estimated to be output from the engine 22 from the torque Tm1 of the motor MG1 reaches or exceeds a return torque that is greater than the torque obtained by subtracting a return threshold value Tref2 from the predetermined torque Tset.

[0045] 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.

[0046] In the hybrid vehicle 20 of the embodiment, the engine 22 is provided with the port injection valve 126 and the in-cylinder injection valve 127, but an engine that does not include the port injection valve and only includes the in-cylinder injection valve may be used.

[0047] 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.

[0048] 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.

[0049] In the embodiment, the present invention has been described as being applied to a hybrid vehicle 20 including 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 capable of generating electricity that is mechanically connected to the output shaft of the engine, and a second motor that can input and output power for running.

[0050] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on Means for Solving the Problems 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".

[0051] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0052] Although the form for carrying out the present invention has been described above using examples, 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 without departing from the scope of the gist of the present invention. [Industrial Applicability]

[0053] The present invention can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0054] 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, 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, 139 variable valve timing mechanism, 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 rotational 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, MG1,MG2 motor.

Claims

1. an engine having an in-cylinder injection valve and a purification device having a catalyst for purifying exhaust gas attached to an exhaust system; 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 traveling; 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: The control device, while executing a rapid catalyst warm-up control for warming up a catalyst of the purification device by operating the engine at a predetermined revolution speed and performing fuel injection during a compression stroke or an expansion stroke and by retarding an ignition timing, When an idle operation of the engine is instructed, a deterioration in combustion of the engine is determined when a rotation speed of the engine falls below the predetermined rotation speed by an amount equal to or greater than a rotation speed threshold value; When an idle operation of the engine is not instructed, a deterioration in combustion of the engine is determined when a torque of the engine estimated from an output torque of the first electric motor falls below a predetermined torque by an amount equal to or greater than a torque threshold value. A hybrid vehicle characterized by

2. 2. The hybrid vehicle according to claim 1, the control device interrupts the rapid catalyst warm-up control when it is determined that combustion in the engine has deteriorated during execution of the rapid catalyst warm-up control. Hybrid car.

3. 3. The hybrid vehicle according to claim 2, The control device, while the rapid catalyst warm-up control is suspended, when an idle operation of the engine is instructed, an improvement in the deterioration of combustion of the engine is determined when a rotation speed of the engine reaches or exceeds the predetermined rotation speed or a return rotation speed that is greater than a rotation speed obtained by subtracting the rotation speed threshold value from the predetermined rotation speed; when an idle operation of the engine is not instructed, the improvement of the deterioration of combustion in the engine is determined when the torque of the engine estimated from the output torque of the first electric motor reaches or exceeds the predetermined torque or a return torque that is greater than a torque obtained by subtracting the torque threshold value from the predetermined torque. Hybrid car.

4. 4. The hybrid vehicle according to claim 3, the control device returns to the rapid catalyst warm-up control when it determines that the deterioration of combustion in the engine has improved while the rapid catalyst warm-up control is interrupted. Hybrid car.

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