JP2013100780A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device which can prevent rough idling in fuel injection recovery which results from fuel evaporation in fuel cut.SOLUTION: In an engine 1 including a port injection injector 10a and a direct injection injector 10b, when a port injection injector end temperature rises to a fuel saturation vapor pressure temperature, the internal combustion engine control device prohibits fuel injection from the port injection injector 10a and performs fuel injection only from the direct injection injector 10b. Subsequently, when an accumulated intake air amount reaches a required intake air amount required for lowering the port injection injector end temperature to the fuel saturation vapor pressure temperature, the internal combustion engine control device permits fuel injection from the port injection injector 10a.

Description

  The present invention relates to a control device for an internal combustion engine mounted on an automobile or the like. In particular, the present invention relates to an improvement in control at the time of return of fuel injection from a fuel cut (stop of fuel injection from an injector accompanying accelerator-off or the like).

  Conventionally, as disclosed in, for example, Patent Document 1 and Patent Document 2 below, when a vehicle equipped with an engine (internal combustion engine) as a driving force source is traveling, the engine speed is a predetermined value or more (or suction) When the driver releases the accelerator pedal (accelerator off) and the engine is driven, the fuel cut condition is satisfied and fuel injection from the injector is stopped (fuel cut). In addition, fuel consumption is reduced. In general, during the fuel cut, the throttle valve opening is reduced and the pumping loss is increased so that the vehicle deceleration corresponding to the driver's accelerator-off operation can be obtained.

  In addition, when the required driving force increases due to the driver depressing the accelerator pedal (accelerator on) during the fuel cut, the fuel injection from the injector is resumed assuming that the fuel cut cancellation condition is satisfied. .

JP 2010-270615 A JP 2011-183986 A

  By the way, as an injector provided in the engine, one that injects fuel into the intake port (hereinafter sometimes referred to as “port injection injector”) or one that injects fuel directly into the cylinder (hereinafter referred to as “port injector”) , Sometimes referred to as “direct injection injector”).

  In the engine provided with the port injection injector, for example, the fuel cut condition is maintained in a state in which the engine temperature (which has a correlation with the coolant temperature and the oil temperature) is relatively high due to, for example, high load operation being performed. When the above is established, fuel injection from the port injector is stopped and the opening of the throttle valve is reduced, the following problems may occur.

  That is, when the opening of the throttle valve becomes small (for example, when the opening becomes “0”), the tip temperature of the injector may increase. This is because the amount of intake air flowing through the intake port decreases as the throttle valve opening decreases, and until that time (until the fuel cut condition is met), the tip of the injector that has been cooled by this intake air This is because is no longer cooled.

  The injector tip temperature rises as the fuel cut duration increases, and when the injector tip temperature reaches a predetermined temperature or higher, the temperature of the fuel present in the injector is saturated. The vapor pressure temperature rises and vapor (bubbles) may be generated in the fuel.

  If the fuel cut cancellation condition is satisfied and fuel injection is resumed in a situation where the vapor is generated, an appropriate fuel injection amount cannot be obtained due to the influence of the vapor (sufficient for stable combustion). There is a possibility that the fuel injection amount cannot be obtained), and in the idling operation, there is a rough idle state in which the engine speed greatly fluctuates, or in some cases, the engine stalls.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a control device for an internal combustion engine that can avoid the above-described problems caused by fuel vaporization during fuel cut. It is in.

-Summary of invention-
The outline of the present invention taken to achieve the above object is that when there is a possibility that vapor is generated in the fuel in the port injector when the fuel cut cancellation condition is satisfied, this port injection is performed. The fuel injection from the injector is prohibited, and the driving force is obtained by other means.

-Solution-
Specifically, the present invention includes an intake passage injection valve that injects fuel toward the intake passage, stops fuel injection from the intake passage injection valve when a predetermined fuel cut condition is satisfied, A control apparatus for an internal combustion engine that resumes fuel injection from the intake passage injection valve when a fuel cut cancellation condition is satisfied is assumed. The control device for the internal combustion engine prohibits fuel injection from the intake passage injection valve when the temperature of the intake passage injection valve when the fuel cut cancellation condition is satisfied reaches the fuel vapor generation temperature. The fuel injection control means is provided.

  With this specific matter, it is possible to avoid a situation in which fuel is injected from the intake passage injection valve in a situation where vapor is generated in the fuel inside the intake passage injection valve. Can not be obtained and the operation of the internal combustion engine becomes unstable.

  Examples of the configuration in which fuel injection from the prohibited intake passage injection valve is permitted include the following. That is, when the fuel cut cancellation condition is satisfied, the temperature of the intake passage injection valve reaches the fuel vapor generation temperature, and when fuel injection from the intake passage injection valve is prohibited, the intake passage injection valve then flows through the intake passage. The fuel injection from the intake passage injection valve is permitted when the intake air amount reaches a predetermined cooling-required intake air amount that can eliminate fuel vapor in the intake passage injection valve.

  In this way, when the intake passage injection valve is cooled by using the cooling action by the intake air flowing through the intake passage to eliminate the fuel vapor, the amount of intake air flowing through the intake passage is a cooling that can eliminate the vapor. By permitting fuel injection from the intake passage injection valve when the required intake air amount is reached, fuel injection from the intake passage injection valve is not prohibited more than necessary. The injection return timing can be set appropriately.

  Examples of means for obtaining a required driving force for the internal combustion engine when fuel injection from the intake passage injection valve is prohibited include the following. That is, as the fuel injection valve, the intake passage injection valve and the in-cylinder injection valve that directly injects fuel into the cylinder are provided. When the temperature of the intake passage injection valve when the fuel cut release condition is satisfied reaches the fuel vapor generation temperature, fuel injection from the intake passage injection valve is prohibited and the required driving force The amount of fuel that can be obtained is injected from the in-cylinder injection valve.

  According to this, even when the fuel injection from the intake passage injection valve is prohibited, the driving force required for the internal combustion engine can be obtained by the fuel injection from the in-cylinder injection valve. There is no shortage of driving force due to the prohibition of fuel injection from the valve.

  Specifically, the temperature of the intake passage injection valve is the temperature of the tip portion of the intake passage injection valve facing the intake passage.

  Since the front end portion of the intake passage injection valve faces the intake passage, it is cooled by intake air flowing through the intake passage when the internal combustion engine is driven, so that vapor is generated in the fuel in the intake passage injection valve. There is no. However, if the fuel cut condition is satisfied and the intake air does not flow into the intake passage, this cooling effect is not exhibited, the temperature of the intake passage injection valve rises, and vapor may be generated in the fuel. Further, since the tip portion of the intake passage injection valve has a particularly small heat capacity, this also tends to increase the temperature, and vapor may be generated in the fuel. In such a situation, after the fuel cut cancellation condition is satisfied, by flowing the intake air through the intake passage, the tip portion of the intake passage injection valve is rapidly cooled, and the generation of vapor is eliminated.

  Further, the temperature of the tip portion of the intake passage injection valve is estimated based on the internal combustion engine coolant temperature and the fuel cut duration when the fuel cut cancellation condition is satisfied.

  The relationship between the internal combustion engine coolant temperature and the fuel cut duration at the time when the fuel cut cancellation condition is satisfied and the temperature of the tip portion of the intake passage injection valve (hereinafter simply referred to as “tip temperature”) is as follows. The higher the internal combustion engine coolant temperature at the time when the condition is satisfied, and the longer the fuel cut duration, the higher the tip temperature. Further, during the fuel cut, combustion in the combustion chamber is not performed, so the temperature of the internal combustion engine (oil temperature or the like) gradually decreases, and the internal combustion engine cooling water temperature also decreases accordingly. That is, the degree of influence of the temperature of the internal combustion engine on the temperature of the tip portion of the intake passage injection valve changes. Thus, the estimation accuracy can be improved by estimating the tip temperature based on the parameter that greatly affects the temperature of the tip of the intake passage injection valve.

  When the internal combustion engine can be rotated by an electric motor (for example, when the internal combustion engine can be motored by a motor in a hybrid vehicle), the temperature of the intake passage injection valve when the fuel cut release condition is satisfied If the internal combustion engine is stopped when the fuel vapor generation temperature is reached, the fuel injection from the intake passage injection valve is prohibited and the drive shaft of the internal combustion engine is rotated by the electric motor to Air is circulated through the passage.

  Thus, even in a situation where the driving force is not required for the internal combustion engine, the drive shaft of the internal combustion engine is rotated by the electric motor so that air flows through the intake passage, and the tip of the intake passage injection valve is cooled by the air. The part is cooled rapidly and the vapor is quickly eliminated.

  In the case where the internal combustion engine and the generator motor are provided as driving sources for driving (for example, in the case of a hybrid vehicle capable of motor driving), the driving in the regeneration mode in which the generator motor performs regenerative power generation when the vehicle decelerates. When the fuel cut cancellation condition is satisfied, the throttle valve provided in the intake passage is opened in the regeneration mode.

  As a result, air is circulated through the intake passage by opening the throttle valve while ensuring deceleration of the vehicle due to regenerative power generation by the generator motor, and the tip portion of the intake passage injection valve is rapidly cooled by the cooling action by this air. Can be made. As a result, the vapor is eliminated at an early stage.

  In the present invention, if there is a possibility that vapor is generated in the fuel in the intake passage injection valve when the fuel cut cancellation condition is satisfied, fuel injection from the intake passage injection valve is prohibited. For this reason, it is possible to prevent the operation of the internal combustion engine from becoming unstable due to failure to obtain an appropriate fuel injection amount.

It is a figure showing a schematic structure of a hybrid vehicle concerning an embodiment. It is a figure which shows schematic structure of the engine mounted in the hybrid vehicle. It is a block diagram which shows the control system of a hybrid vehicle. It is a flowchart figure which shows the procedure of F / C return control which concerns on 1st Embodiment. It is a figure which shows an example of a cooling required intake air amount setting map. It is a figure which shows the relationship between integrated intake air amount and injector front-end | tip temperature. It is a figure which shows an example of a time-dependent change of injector tip temperature. It is a flowchart figure which shows the procedure of the port injection control in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to an FF (front engine / front drive) type hybrid vehicle will be described.

  FIG. 1 is a schematic configuration diagram showing a hybrid vehicle according to the present embodiment. As shown in FIG. 1, a hybrid vehicle HV includes an engine (internal combustion engine) 1 that generates a driving force for traveling the vehicle, a first motor generator MG1 (first generator motor) that mainly functions as a generator, A second motor generator MG2 (second generator motor) that functions as a motor, a power split mechanism 3, a reduction mechanism 4, a counter drive gear 51, a counter driven gear 52, a final gear 53, a differential device 54, a front wheel axle (drive shaft) 61, 61, front wheels (drive wheels) 6L, 6R, an ECU (Electronic Control Unit) 100, and the like, and the control device of the present invention is realized by a program executed by the ECU 100.

  The ECU 100 includes, for example, an HV (hybrid) ECU, an engine ECU, a motor ECU, a battery ECU, and the like, and these ECUs are connected so as to communicate with each other.

  Next, components of the engine 1, the motor generators MG1 and MG2, the power split mechanism 3, the reduction mechanism 4, the ECU 100, and the like will be described.

-Engine-
The engine 1 is a power device such as a gasoline engine or a diesel engine, and burns fuel to output power.

  FIG. 2 shows a schematic configuration of the engine 1 (only one cylinder). As shown in FIG. 2, the engine 1 is a spark ignition type reciprocating engine 1, and includes a port injection type injector (port injection injector; intake passage injection valve) 10a and an in-cylinder direct injection type injector (direct injection injector; cylinder). (Inner injection valve) 10b, and an air-fuel mixture is generated in the combustion chamber 12 by the fuel injected from at least one of the injectors 10a and 10b.

  A piston 13 is provided in each cylinder 11 of the engine 1, and the piston 13 reciprocates in the cylinder 11 as the air-fuel mixture burns.

  The injectors 10a and 10b are respectively connected to delivery pipes 10c and 10d as fuel pressure accumulating containers, and fuel is supplied from the delivery pipes 10c and 10d. The port injector 10a is supplied with a relatively low pressure fuel, and the direct injection injector 10b is supplied with a relatively high pressure fuel (fuel boosted by a high pressure fuel pump (not shown)). In addition, an injection driver 10e for adjusting the fuel pressure is connected to the direct injection injector 10b. The fuel injected into the combustion chamber 12 by the injectors 10a and 10b forms an air-fuel mixture together with the air A introduced into the combustion chamber 12 through the intake manifold 14a constituting a part of the intake passage 14, It is ignited by the spark plug 15 and burns. The combustion pressure of the air-fuel mixture is transmitted to the piston 13 and causes the piston 13 to reciprocate. The intake valve 16 is driven by an intake camshaft 16a. The intake camshaft 16a is rotationally driven by the power extracted from the crankshaft 18 being transmitted by a timing belt or the like.

  The reciprocating motion of the piston 13 is transmitted to the crankshaft 18 via the connecting rod 13a, where it is converted into a rotational motion and taken out as the output of the engine 1. The output of the engine 1 is transmitted to the input shaft 21 via the crankshaft 18 and the damper 20 (see FIG. 1). The damper 20 is a coil spring type transaxle damper, for example, and absorbs torque fluctuations of the engine 1.

  Further, the air-fuel mixture after combustion becomes exhaust gas Ex, and is discharged to the exhaust manifold 19a which is a part of the exhaust passage 19 as the exhaust valve 17 is opened. The exhaust gas Ex is purified by a catalytic converter 19b provided on the downstream side of the exhaust manifold 19a, and then released into the atmosphere. The exhaust valve 17 is driven by an exhaust camshaft 17a. The exhaust camshaft 17a is rotationally driven by the power extracted from the crankshaft 18 being transmitted by a timing belt or the like.

  Further, the intake air amount of the engine 1 is adjusted by the throttle body 8 provided on the downstream side of the air cleaner 14 b in the intake passage 14. The throttle body 8 includes a throttle valve 81 that is a butterfly valve, a throttle motor 82 that opens and closes the throttle valve 81, and a throttle opening sensor 103 that detects the opening of the throttle valve 81. The ECU 100 acquires the output from the accelerator opening sensor 101 that detects the opening of the accelerator operated by the driver (driver), sends a control signal to the throttle motor 82, and the throttle valve from the throttle opening sensor 103. Based on the feedback signal of the opening of 81, the throttle valve 81 is controlled to an appropriate opening. As a result, the amount of air A introduced into the cylinder 11 of the engine 1 is controlled. Further, as will be described later, the opening of the throttle valve 81 is controlled to be substantially “0” during the fuel cut.

Sensors for acquiring information related to operation and information related to control of the engine 1 are attached to the engine 1 in order to control its operation. The sensors include the accelerator opening sensor 101, a crank position sensor 102 used for detecting the engine speed, an air flow meter 108 for detecting the intake air amount, an intake air temperature sensor 109 for detecting the intake air temperature, a water jacket. A knock sensor 111 comprising a water temperature sensor 107 for detecting the cooling water temperature in the inside, an O ₂ sensor 110 for detecting the oxygen concentration in the exhaust gas Ex, and a vibration detection sensor for detecting vibration of the cylinder block for use in knock determination control. Etc.

  The engine 1 according to the present embodiment includes the two types of injectors 10a and 10b, so that fuel injection in one of the port injection drive mode, the in-cylinder injection drive mode, and the common injection drive mode, for example, is performed. The form is feasible.

  In the port injection drive mode, the air cleaned by the air cleaner 14b is taken into the intake port via the throttle valve 81 and fuel is injected from the port injection injector 10a to mix the intake air and the fuel. As the valve 16 opens, it is sucked into the combustion chamber 12 and burned by an electric spark from the spark plug 15. The reciprocating motion of the piston 13 pushed down by this energy is converted into the rotational motion of the crankshaft 18. This port injection driving mode is executed, for example, during low load operation where the driving force required for the engine 1 is relatively low. In the in-cylinder injection drive mode, air is sucked into the combustion chamber 12 as described above, and fuel is injected into the combustion chamber 12 from the direct injection injector 10b after the intake stroke or the compression stroke is reached. The crankshaft 18 is rotated and burned by electric sparks generated by the spark plug 15 to obtain the rotational movement of the crankshaft 18. This in-cylinder injection drive mode is executed, for example, during high load operation where the drive force required for the engine 1 is relatively high. In the common injection drive mode, when air is sucked into the combustion chamber 12, fuel is injected from the port injection injector 10a and fuel is injected from the direct injection injector 10b into the combustion chamber 12 during the intake stroke or compression stroke. Get a rotational movement. These drive modes are switched based on the operating state of the engine 1 or the driving force required for the engine 1 in the hybrid system. The exhaust from the engine 1 is purified by the catalytic converter 19b and then discharged to the outside air.

-Motor generator-
The first motor generator MG1 is an AC synchronous generator including a rotor MG1R made of a permanent magnet supported so as to be relatively rotatable with respect to the input shaft 21, and a stator MG1S wound with a three-phase winding. It functions as a generator and also as an electric motor (electric motor). Similarly, the second motor generator MG2 includes an AC synchronous generator including a rotor MG2R made of a permanent magnet supported so as to be relatively rotatable with respect to the input shaft 21, and a stator MG2S wound with a three-phase winding. It functions as an electric motor (electric motor) as well as a generator.

  As shown in FIG. 3, first motor generator MG <b> 1 and second motor generator MG <b> 2 are each connected to battery (power storage device) 300 via inverter 200. Inverter 200 is controlled by ECU 100, and regeneration or power running (assist) of each motor generator MG 1, MG 2 is set by the control of inverter 200. The regenerative power at that time is charged into the battery 300 via the inverter 200. In addition, driving power for each of the motor generators MG1 and MG2 is supplied from the battery 300 via the inverter 200.

-Power split mechanism-
As shown in FIG. 1, the power split mechanism 3 includes an external gear sun gear S3 that rotates at the center of a plurality of gear elements, and an external gear pinion gear P3 that revolves around the sun gear S3 while rotating around its periphery. And a planetary gear mechanism having a ring gear R3 which is an internal gear formed in a hollow ring so as to mesh with the pinion gear P3, and a planetary carrier CA3 which supports the pinion gear P3 and rotates through the revolution of the pinion gear P3. Yes. The planetary carrier CA3 is connected to the input shaft 21 on the engine 1 side so as to rotate together. The sun gear S3 is connected to the rotor MG1R of the first motor generator MG1 so as to rotate together.

  The power split mechanism 3 transmits at least one driving force of the engine 1 and the second motor generator MG2 via a counter drive gear 51, a counter driven gear 52, a final gear 53, a differential device 54, and drive shafts 61 and 61. It is transmitted to the left and right drive wheels 6L, 6R.

-Reduction mechanism-
The reduction mechanism 4 is rotatably supported by an external gear sun gear S4 that rotates at the center of a plurality of gear elements and a carrier (transaxle case) CA4, and is an external gear pinion gear P4 that rotates while circumscribing the sun gear S4. And a planetary gear mechanism having a ring gear R4 of an internal gear formed in a hollow annular shape so as to mesh with the pinion gear P4. The ring gear R4 of the reduction mechanism 4, the ring gear R3 of the power split mechanism 3, and the counter drive gear 51 are integrated with each other. Sun gear S4 is connected to rotor MG2R of second motor generator MG2 so as to rotate together.

  The reduction mechanism 4 decelerates the driving force of the second motor generator MG2 at an appropriate reduction ratio. The reduced driving force is transmitted to the left and right drive wheels 6L and 6R via the counter drive gear 51, the counter driven gear 52, the final gear 53, the differential device 54, and the drive shaft 61.

-Shift operation device-
A shift operation device 7 (see FIG. 3) is arranged near the driver's seat in the hybrid vehicle HV. The shift operating device 7 is provided with a shift lever 71 so that it can be displaced. The shift operating device 7 in this example includes a drive range (D range) for forward travel, a brake range (B range) for forward travel with a large braking force (engine brake) when the accelerator is off, and a reverse travel range. A reverse range (R range) and a neutral range (N range) are set, and the driver can displace the shift lever 71 to a desired range. These positions of the D range, B range, R range, and N range are detected by the shift position sensor 104. An output signal of the shift position sensor 104 is input to the ECU 100. Note that the parking position (P position) can be set by a separately arranged P switch.

-ECU-
The ECU 100 is an electronic control device that performs various controls including operation control of the engine 1 and cooperative control of the engine 1 and the motor generators MG1 and MG2, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM. (Random Access Memory) and a backup RAM.

  The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results from the CPU, data input from each sensor, and the like, and the backup RAM is a nonvolatile memory that stores data to be saved when an ignition switch (not shown) is turned off. Memory.

As shown in FIG. 3, the ECU 100 includes an accelerator opening sensor 101, a crank position sensor 102, a throttle opening sensor 103, a shift position sensor 104, a wheel speed sensor 105 that detects the rotational speed of the wheels 6L and 6R, a brake. A brake pedal sensor 106 that detects a pedaling force (braking force) against the pedal, the water temperature sensor 107, the air flow meter 108, an intake air temperature sensor 109, an O ₂ sensor 110, a knock sensor 111, and the like are connected. This signal is input to the ECU 100. Further, a current sensor (not shown) for detecting the charge / discharge current of the battery 300, a battery temperature sensor, and the like are also connected, and signals from these sensors are also input to the ECU 100.

  The ECU 100 also includes a throttle motor 82 that opens and closes the throttle valve 81 of the engine 1, the port injector 10a, the direct injector 10b (injection driver 10e), an igniter 15a that adjusts the ignition timing of the spark plug 15, and the like. It is connected.

  The ECU 100 executes various controls of the engine 1 such as throttle opening control (intake air amount control), fuel injection amount control, and ignition timing control of the engine 1 based on the output signals of the various sensors described above. In addition, the entire hybrid system is controlled.

  Furthermore, in order to manage the battery 300, the ECU 100 manages the battery 300 based on the integrated value of the charge / discharge current detected by the current sensor, the battery temperature detected by the battery temperature sensor, etc. SOC: State of Charge), input limit Win and output limit Wout of the battery 300, and the like are calculated.

  In addition, the inverter 200 is connected to the ECU 100. Inverter 200 includes an IPM (Intelligent Power Module) for controlling motor generators MG1 and MG2. Each IPM is constituted by a plurality of (for example, six) semiconductor switching elements (for example, an IGBT (Insulated Gate Bipolar Transistor)).

  For example, inverter 200 converts DC current from battery 300 into motor generators MG1 and MG2 in accordance with a command signal from ECU 100 (for example, torque command value of first motor generator MG1, torque command value of second motor generator MG2). In order to charge the battery 300 with the AC current generated by the first motor generator MG1 by the power of the engine 1 and the AC current generated by the second motor generator MG2 by the regenerative brake. Convert to DC current. Inverter 200 supplies the alternating current generated by first motor generator MG1 as drive power for second motor generator MG2 in accordance with the traveling state.

-Driving mode-
In the hybrid vehicle according to the present embodiment, when the engine 1 is not operating efficiently, such as when starting or running at a low speed, the vehicle travels only by the second motor generator MG2 (hereinafter also referred to as “EV traveling”). Do. Further, EV traveling is also performed when the driver selects the EV traveling mode using a traveling mode selection switch disposed in the vehicle interior.

  On the other hand, during normal running, for example, the power split mechanism 3 divides the power of the engine 1 into two paths, while the drive wheels 6L and 6R are directly driven (driven by direct torque), and the first motor generator MG1 is turned on the other hand. Drive to generate electricity. At this time, the second motor generator MG2 is driven by the generated electric power to assist driving of the driving wheels 6L and 6R (driving by an electric path). In this way, the power split mechanism 3 functions as a differential mechanism, and the main part of the power from the engine 1 is mechanically transmitted to the drive wheels 6L and 6R by the differential action, and the power from the engine 1 is transmitted. A function as a transmission (electric continuously variable transmission) in which the gear ratio is electrically changed by electrically transmitting the remaining portion using the electric path from the first motor generator MG1 to the second motor generator MG2. Is demonstrated. As a result, the engine speed and the engine torque can be freely operated without depending on the speed and torque of the drive wheels 6L and 6R (ring gears R3 and R4), which is required for the drive wheels 6L and 6R. While obtaining the driving force, it is possible to obtain the engine operating state in which the fuel consumption rate is optimized.

  Further, at the time of high speed traveling, the electric power from the battery (battery for traveling) 300 is further supplied to the second motor generator MG2, and the output of the second motor generator MG2 is increased to drive the driving wheels 6L and 6R. Add (driving force assist; power running).

  Furthermore, at the time of deceleration, the second motor generator MG2 functions as a generator to perform regenerative power generation, and the recovered power is stored in the battery 300. When the charge amount of the battery 300 is reduced and charging is particularly necessary, the output of the engine 1 is increased to increase the power generation amount by the first motor generator MG1 and the charge amount to the battery 300 is increased. Of course, there is a case where control is performed to increase the driving force of the engine 1 as necessary even during low-speed traveling. For example, as described above, when the battery 300 needs to be charged, when an auxiliary device such as an air conditioner is driven, when the temperature of the cooling water of the engine 1 is increased to a predetermined temperature, or when the vehicle is accelerated rapidly, etc. is there.

  Furthermore, in the hybrid vehicle, the engine 1 is stopped in order to improve fuel efficiency depending on the driving state of the vehicle and the state of the battery 300. And after that, the driving state of the vehicle and the state of the battery 300 are detected, and the engine 1 is restarted. Thus, in the hybrid vehicle, the engine 1 is intermittently operated even when the ignition switch is in the ON position.

-Outline of fuel cut control-
The ECU 100 also executes the following fuel cut control in order to reduce fuel consumption.

  In this fuel cut control, for example, the engine speed detected by the crank position sensor 102 is equal to or higher than a predetermined value (fuel cut speed: 1000 rpm, for example), and the accelerator pedal detected by the accelerator opening sensor 101 is used. When the opening degree of the engine is "0" (accelerator OFF), it is determined that the fuel cut condition is satisfied, and the fuel injection from each of the injectors 10a and 10b is stopped. As a result, fuel consumption can be reduced and exhaust emission can be improved. Further, during the fuel cut, the throttle valve 81 is reduced in opening and the pumping loss is increased so that the vehicle deceleration corresponding to the driver's accelerator-off operation can be obtained. At this time, the second motor generator MG2 may perform regenerative power generation.

  When the accelerator pedal is depressed during the fuel cut (when acceleration is requested), the fuel cut release condition is satisfied, the fuel cut is stopped, and the fuel injection from at least one of the injectors 10a and 10b is resumed. To do. The injectors 10a and 10b used at the time of resuming fuel injection are basically modes determined according to the operating state of the engine 1 (in the port injection drive mode, the in-cylinder injection drive mode, and the common injection drive mode). However, in the case of the present embodiment, the fuel injection from the port injector 10a is prohibited when the predetermined condition is satisfied as will be described later (details will be described later). ).

−Return control from fuel cut−
The feature of the present embodiment is that when the fuel cut control described above is executed, the required driving force is increased by the driver depressing the accelerator pedal, etc., and the fuel cut release condition is satisfied (hereinafter referred to as “ It may be called “F / C return control”). Hereinafter, a plurality of embodiments of the return control from the fuel cut will be described.

(First embodiment)
First, the first embodiment will be described. In the present embodiment, in order to facilitate understanding, when the fuel cut cancellation condition is satisfied, the driving force from the engine 1 is required, and fuel is injected from at least one of the injectors 10a and 10b to A case where a driving force is output will be described.

  First, the outline of the return control will be described. For example, the fuel cut condition is satisfied when the engine temperature (cooling water temperature) is relatively high due to the high load operation, the fuel injection from the injectors 10a and 10b is stopped, and the throttle valve 81 When the opening degree of becomes small, the tip temperature of the port injection injector 10a may rise. This is because the amount of intake air flowing through the intake passage 14, particularly the intake passage in the intake manifold 14a is reduced, and until that time (until the fuel cut condition is satisfied), the front end portion of the port injection injector 10a that has been cooled by this intake air. This is because is no longer cooled.

  The tip temperature of the port injector 10a increases as the fuel cut duration increases, and when the tip temperature reaches a predetermined temperature or higher (for example, 120 ° C. or higher), the tip temperature of the port injector 10a is increased inside the port injector 10a. The temperature of the existing fuel may rise to the saturated vapor pressure temperature, and vapor (bubbles) may be generated in the fuel.

  When the fuel cut cancellation condition is satisfied in the situation where the vapor is generated and the fuel injection is resumed, an appropriate fuel injection amount cannot be obtained due to the influence of the vapor (combustion in the combustion chamber 12 is stabilized). A sufficient fuel injection amount obtained in this manner cannot be obtained), a rough idle state in which the engine speed during idling operation fluctuates greatly, or an engine stall may occur in some cases.

  In order to avoid such a phenomenon, in the return control from the fuel cut in the present embodiment, when the tip temperature of the port injector 10a is increased to the saturated vapor pressure temperature of the fuel, the fuel cut cancellation condition is satisfied. Even so, the fuel injection from the port injector 10a is prohibited (the fuel injection prohibiting operation by the fuel injection control means in the present invention), the fuel injection is performed only from the direct injection injector 10b, and the drive required for the engine 1 is performed. Generate power. Thereafter, fuel injection from the port injector 10a is permitted on condition that the tip temperature of the port injector 10a has decreased to below the saturated vapor pressure temperature of the fuel.

  Hereinafter, the return control from the fuel cut will be specifically described with reference to the flowchart of FIG. This flowchart is repeatedly executed every several milliseconds after the fuel cut cancellation condition is satisfied or every time the crankshaft 18 rotates by a predetermined rotation angle.

  First, in step ST1, the tip temperature of the port injector 10a (hereinafter referred to as “injector tip temperature”) is estimated. Specifically, the injector tip temperature is estimated based on the coolant temperature and the fuel cut duration when the fuel cut release condition is satisfied. The cooling water temperature is detected by the water temperature sensor 107. In addition, the fuel cut duration is determined after the fuel cut condition is satisfied (the accelerator pedal opening detected by the accelerator opening sensor 101 is set to “0” (accelerator OFF)). From the ECU 100, a period until the fuel cut cancellation condition is satisfied (until the accelerator pedal opening detected by the accelerator opening sensor 101 is increased (accelerator ON) and the fuel cut cancellation condition is satisfied) is established. It is obtained by measuring with a counter provided in The ROM stores a tip temperature estimation map for estimating the injector tip temperature using the cooling water temperature and the fuel cut duration when these fuel cut cancellation conditions are satisfied as parameters. The injector tip temperature is estimated by referring to the estimation map. This tip temperature estimation map is created in advance by experiments and simulations and stored in the ROM. The higher the coolant temperature at the time when the fuel cut release condition is satisfied and the longer the fuel cut duration, the longer the injector tip A high value is obtained as an estimated value as the temperature. During fuel cut, combustion in the combustion chamber 12 is not performed, so the temperature of the engine 1 (oil temperature or the like) gradually decreases, and the cooling water temperature also decreases accordingly. That is, the degree of influence of the temperature of the engine 1 on the injector tip temperature changes with time. Thus, the estimation accuracy can be improved by estimating the injector tip temperature based on the parameter that greatly affects the injector tip temperature.

  After estimating the injector tip temperature, the process proceeds to step ST2, and whether or not the estimated injector tip temperature exceeds the saturated vapor pressure temperature of fuel (temperature at which vapor is generated; vapor generation temperature in the present invention). Determine whether. The saturated vapor pressure temperature is set to 120 ° C., for example. Since the temperature at which vapor is generated in the fuel depends on the fuel pressure, the vapor generation temperature is calculated according to the fuel pressure, and the calculated vapor generation temperature is compared with the estimated injector tip temperature. Is preferred.

  If the injector tip temperature is equal to or lower than the saturated vapor pressure temperature of the fuel and NO is determined in step ST2, it is determined that no vapor is generated in the fuel inside the port injector 10a, and the fuel from the port injector 10a It returns as it is to allow fuel injection. That is, in this case, fuel injection from the port injector 10a is started when the port injection drive mode or the common injection drive mode is entered after the fuel cut cancellation condition is satisfied.

  On the other hand, if the injector tip temperature exceeds the saturated vapor pressure temperature of the fuel and the determination in step ST2 is YES, the process proceeds to step ST3, and there is a possibility that vapor is generated in the fuel inside the port injector 10a. Therefore, the fuel injection from the port injector 10a is prohibited. Along with the prohibition of fuel injection from the port injector 10a, fuel injection from only the direct injector 10b is performed in the combustion chamber 12, and the driving force required for the engine 1 by this fuel is provided. generate. That is, the fuel injection amount for obtaining the driving force required for the engine 1 is calculated, and the entire required fuel injection amount is injected from the direct injection injector 10b. It should be noted that the throttle valve 81 is opened as the fuel cut cancellation condition is satisfied, and the opening degree is adjusted according to the engine load.

  Thereafter, in step ST4, it is determined whether or not the integrated intake air amount (hereinafter simply referred to as “integrated intake air amount”) from when the fuel cut cancellation condition is satisfied exceeds the cooling-required intake air amount. This integrated intake air amount is obtained by integrating the intake air amount detected by the air flow meter 108 from the time when the fuel cut cancellation condition is satisfied. The amount of intake air required for cooling is the amount of intake air required for the injector tip temperature exceeding the saturated vapor pressure temperature to become equal to or lower than the saturated vapor pressure temperature. That is, when the intake air flows through the intake passage 14, the intake air removes heat from the tip portion of the port injection injector 10a, and the injector tip temperature gradually decreases. The amount of intake air required to be equal to or lower than the pressure temperature is given as the amount of intake air required for cooling. This required intake air amount for cooling is determined by the shape and heat capacity of the tip portion of the port injection injector 10a, and the injector tip temperature when the fuel cut release condition is satisfied. Since the shape and heat capacity of the tip portion of the port injector 10a are constant depending on the configuration of the port injector 10a, the intake air amount required for cooling is set using the injector tip temperature when the fuel cut cancellation condition is satisfied as a parameter. A cooling necessary intake air amount setting map is stored in the ROM. By referring to this cooling required intake air amount setting map, the cooling required intake air amount is set. This required intake air amount setting map has been created in advance by experiments and simulations, and a larger value is obtained as the required intake air amount as the injector tip temperature becomes higher when the fuel cut release condition is satisfied. It has become. FIG. 5 is a diagram showing an example of the cooling necessary intake air amount setting map. As shown in FIG. 5, in the region where the injector tip temperature exceeds the saturated vapor pressure temperature (vapor generation temperature) Tv, the higher the tip temperature of the injector, the larger the amount of intake air required for cooling is acquired. FIG. 6 is a diagram showing the relationship between the cumulative intake air amount and the injector tip temperature. Thus, since the amount of decrease in the injector tip temperature increases as the integrated intake air amount increases, the higher the injector tip temperature, the larger the amount of intake air required for cooling. It becomes possible to reduce to (vapor generation temperature).

  If the integrated intake air amount is less than or equal to the cooling-required intake air amount, NO is determined in step ST4, and the process waits for the integrated intake air amount to exceed the cooling-required intake air amount.

  On the other hand, if the integrated intake air amount exceeds the cooling-required intake air amount and a YES determination is made in step ST4, the process proceeds to step ST5, assuming that the vapor in the port injector 10a has been eliminated, and the port injector 10a. Allow fuel injection from. That is, in the port injection driving mode or the common injection driving mode, fuel injection from the port injector 10a is started.

  If there is a possibility that vapor exists in the port injector 10a by repeating the above operation, fuel injection from the port injector 10a is prohibited and the fuel is injected into the port injector 10a. When the vapor does not exist or when the vapor is eliminated, fuel injection from the port injector 10a is permitted.

  FIG. 7 is a diagram illustrating an example of a change with time of the injector tip temperature when the above-described F / C return control is executed. In FIG. 7, the case where the injector tip temperature when the fuel cut cancellation condition is satisfied exceeds the vapor generation temperature Tv by a solid line, and the case where it does not exceed the vapor generation temperature Tv is indicated by an alternate long and short dash line.

  As shown in FIG. 7, when the fuel cut is started, the injector tip temperature rises as the opening of the throttle valve 81 decreases. If the injector tip temperature at the time when the fuel cut release condition is satisfied exceeds the vapor generation temperature Tv (solid line), the injector tip temperature decreases to the vapor generation temperature Tv after the fuel cut release condition is satisfied. Until this time, fuel injection is prohibited (see “port fuel injection prohibition period of port injector” in the figure).

  As described above, in the present embodiment, when the tip temperature of the port injector 10a at the time when the fuel cut cancellation condition is satisfied rises to the saturated vapor pressure temperature of the fuel, the fuel injection from the port injector 10a is performed. The fuel injection is performed only from the direct injection injector 10b, and the driving force required for the engine 1 is generated. For this reason, in a situation where vapor is generated in the port injector 10a, fuel is injected from the port injector 10a and an appropriate fuel injection amount cannot be obtained, resulting in a rough idle state. You can avoid a stall.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, in addition to the first embodiment described above, as a method of obtaining the deceleration of the vehicle during the fuel cut, a case where the opening of the throttle valve 81 is reduced and the regeneration by the second motor generator MG2 are performed. This is in consideration of the case of generating electricity. This will be specifically described below.

  FIG. 8 is a flowchart showing a procedure of port injection control according to the present embodiment. This flowchart is repeatedly executed every several milliseconds after an ignition switch (not shown) is turned on.

  First, in step ST11, it is determined whether or not the current operating state of the engine 1 is in a fuel cut state and the throttle valve 81 is in a state where it can be opened. The determination as to whether or not the current operating state of the engine 1 is in a fuel cut is a state in which the fuel cut condition is satisfied and the fuel cut cancellation condition is not yet satisfied. Determined to be in the middle. The determination of whether or not the throttle valve 81 can be opened is a determination of whether or not the vehicle is in an operating state in which the deceleration of the vehicle can be ensured even when the throttle valve 81 is opened. In other words, as described above, during fuel cut, the throttle valve 81 is reduced in opening and the pumping loss is increased so that the vehicle deceleration corresponding to the driver's accelerator-off operation can be obtained. Generally, when the deceleration of the vehicle is obtained by other means, the opening degree of the throttle valve 81 can be increased. For example, when the second motor generator MG2 is performing regenerative power generation, the deceleration of the vehicle is obtained by this amount of regenerative energy, so the opening degree of the throttle valve 81 can be increased. If the fuel cut is in progress, the engine speed does not increase (raise) even if the opening of the throttle valve 81 is increased.

  If YES is determined in step ST11, the process proceeds to step ST12 and the throttle valve 81 is opened. On the other hand, if NO is determined in step ST11, the process proceeds to step ST13 and the throttle valve 81 is closed.

  Thereafter, in step ST14, as in the case of the first embodiment described above, the injector tip temperature is estimated as the fuel cut cancellation condition is satisfied. Specifically, the injector tip temperature is estimated based on the coolant temperature and the fuel cut duration when the fuel cut release condition is satisfied. This estimation operation is performed in the same manner as step ST1 of the flowchart of FIG. 4 in the first embodiment.

  Thereafter, the process proceeds to step ST15, in which it is determined whether or not the estimated injector tip temperature exceeds the saturated vapor pressure temperature of fuel (temperature at which vapor is generated). This determination operation is performed in the same manner as step ST2 of the flowchart of FIG. 4 in the first embodiment.

  If the injector tip temperature is equal to or lower than the saturated vapor pressure temperature of the fuel and NO is determined in step ST15, it is determined that no vapor is generated in the fuel inside the port injector 10a, and the fuel from the port injector 10a It returns as it is to allow fuel injection.

  On the other hand, if the injector tip temperature exceeds the saturated vapor pressure temperature of the fuel, and YES is determined in step ST15, the process proceeds to step ST16, and there is a possibility that vapor is generated in the fuel inside the port injector 10a. Therefore, the fuel injection from the port injector 10a is prohibited.

  After the fuel injection from the port injector 10a is thus prohibited, the process proceeds to step ST17, where it is determined whether or not the engine 1 is currently stopped (rotation speed is “0”). This determination is made based on the engine speed detected by the crank position sensor 102. Alternatively, it is possible to determine whether or not the required driving force for the engine 1 is “0” as the driving force request signal from the ECU 100. For example, if the vehicle is traveling in the EV mode, or if the vehicle is in a state where idling is stopped in order to reduce fuel consumption when the vehicle is stopped (so-called idling stop), YES in step ST17 Determined.

  If the engine 1 is being driven and NO is determined in step ST17, air flows in the intake passage 14, and the tip of the port injector 10a is assumed to be cooled, and the process proceeds to step ST19.

  On the other hand, if the engine 1 is stopped and YES is determined in step ST17, the process proceeds to step ST18, and the engine 1 is rotated so that the intake air flows through the intake passage 14. As means for rotating the engine 1, fuel injection from the direct injection injector 10b and ignition of the ignition plug 15 are performed to cause the engine 1 to perform an idling operation (specifically, the engine 1 is driven by the first motor generator MG1). Both the fuel injection from the direct injection injector 10b and the ignition of the spark plug 15 in the cranked state) and the fuel injection from the direct injection injector 10b and the ignition of the ignition plug 15 are both prohibited, and the first motor generator MG1 In which the crankshaft 18 is rotated (generally referred to as “motoring”). By rotating the engine 1 in this manner, the intake air flows into the intake passage 14, thereby cooling the front end portion of the port injector 10 a.

  Thereafter, the process proceeds to step ST19, where it is determined whether or not the integrated intake air amount (integrated intake air amount) from when the fuel cut cancellation condition is satisfied exceeds the required intake air amount for cooling. This determination operation is performed in the same manner as step ST4 of the flowchart of FIG. 4 in the first embodiment.

  If the integrated intake air amount is less than or equal to the cooling-required intake air amount, NO is determined in step ST19, and the process waits for the integrated intake air amount to exceed the cooling-required intake air amount.

  On the other hand, if the cumulative intake air amount exceeds the cooling-required intake air amount and a YES determination is made in step ST19, the process proceeds to step ST20, assuming that the vapor in the port injector 10a has been eliminated, and the port injector 10a. Allow fuel injection from. That is, in the port injection driving mode or the common injection driving mode, fuel injection from the port injector 10a is started.

  If there is a possibility that vapor exists in the port injector 10a by repeating the above operation, fuel injection from the port injector 10a is prohibited and the fuel is injected into the port injector 10a. When the vapor does not exist or when the vapor is eliminated, fuel injection from the port injector 10a is permitted.

  Also in the present embodiment, in a situation where vapor is generated inside the port injection injector 10a, fuel injection is performed from the port injection injector 10a, and an appropriate fuel injection amount cannot be obtained. It can be avoided that the engine stalls. In the case of the present embodiment, the first motor generator MG1 rotates the crankshaft 18 of the engine 1 to cause air to flow through the intake passage 14, and the cooling of the injector rapidly cools the injector tip temperature. Vapor can be eliminated early. Further, while ensuring deceleration of the vehicle by regenerative power generation by the second motor generator MG2, air is circulated through the intake passage 14 by opening the throttle valve 81, and the injector tip temperature is rapidly cooled by this air cooling action. It can also be made. This also eliminates vapor at an early stage.

-Other embodiments-
In each of the embodiments described above, the case where the present invention is applied to the control of an FF (front engine / front drive) type hybrid vehicle has been described. However, the present invention is not limited to this, and FR (front engine / rear) The present invention can also be applied to control of a drive) hybrid vehicle and a four-wheel drive hybrid vehicle. Further, the present invention can be applied not only to a hybrid vehicle but also to a conventional vehicle having only an engine as a driving source for traveling.

  Moreover, in each embodiment, although the example which applied this invention to the hybrid vehicle by which two electric motors of 1st motor generator MG1 and 2nd motor generator MG2 were mounted was shown, the hybrid vehicle by which one electric motor was mounted is shown. The present invention can also be applied to control and control of a hybrid vehicle equipped with three or more electric motors.

  Moreover, in each embodiment, the case where this invention was applied to the gasoline engine mounted in the motor vehicle was demonstrated. The present invention is applicable not only to automobiles but also to engines used for other purposes. Also, the number of cylinders and the engine type (separate types such as in-line type, V type, and horizontally opposed type) are not particularly limited.

  In addition, the present invention can be applied to a hybrid vehicle that does not include the direct injection injector 10b as an injector but is equipped with an engine that includes only the port injection injector 10a. In this case, when fuel injection from the direct injection injector 10b is prohibited, a driving force is obtained by a motor (for example, the second motor generator MG2).

  In each of the above embodiments, the amount of intake air required for cooling is set as the amount of intake air required for the injector tip temperature to be equal to or lower than the saturated vapor pressure temperature. The present invention is not limited to this, and a predetermined amount of intake air is added to the amount of intake air required for the injector tip temperature to be equal to or lower than the saturated vapor pressure temperature in order to reliably eliminate the vapor in the port injector 10a. This may be set as the intake air amount required for cooling.

  The present invention can be applied to fuel injection control when a fuel cut cancellation condition is satisfied in an engine including a port injection injector and a direct injection injector.

1 engine (internal combustion engine)
10a Port injection injector (intake passage injection valve)
10b Direct injection injector (in-cylinder injection valve)
14 Intake passage 81 Throttle valve 82 Throttle motor MG1 First motor generator (electric motor)
MG2 Second motor generator (generator motor)
100 ECU
101 Accelerator opening sensor 102 Crank position sensor 107 Water temperature sensor 108 Air flow meter

In the case where the internal combustion engine and the generator motor are provided as driving sources for driving (for example, in the case of a hybrid vehicle capable of motor driving), the driving in the regeneration mode in which the generator motor performs regenerative power generation when the vehicle decelerates. It has become possible, when the fuel cut condition is satisfied, the regenerative mode is configured to open the throttle valve disposed in an intake passage.

Claims (7)

When an intake passage injection valve for injecting fuel toward the intake passage is provided and fuel injection from the intake passage injection valve is stopped when a predetermined fuel cut condition is satisfied, and a predetermined fuel cut release condition is satisfied In the control device for an internal combustion engine that resumes fuel injection from the intake passage injection valve,
Fuel injection control means is provided for prohibiting fuel injection from the intake passage injection valve when the temperature of the intake passage injection valve when the fuel cut cancellation condition is satisfied reaches the fuel vapor generation temperature. A control device for an internal combustion engine. The control apparatus for an internal combustion engine according to claim 1,
The fuel injection control means, when the temperature of the intake passage injection valve when the fuel cut release condition is satisfied has reached the fuel vapor generation temperature, and when fuel injection from the intake passage injection valve is prohibited, Thereafter, when the amount of intake air flowing through the intake passage reaches a predetermined amount of intake air required for cooling that can eliminate fuel vapor in the intake passage injection valve, fuel injection from the intake passage injection valve is permitted. A control device for an internal combustion engine. The control device for an internal combustion engine according to claim 1 or 2,
As a fuel injection valve, the intake passage injection valve and a cylinder injection valve for directly injecting fuel into the cylinder,
The fuel injection control means prohibits fuel injection from the intake passage injection valve when the temperature of the intake passage injection valve when the fuel cut cancellation condition is satisfied reaches the fuel vapor generation temperature. In addition, the control device for an internal combustion engine is configured to inject an amount of fuel capable of obtaining a required driving force from the in-cylinder injection valve. The control device for an internal combustion engine according to claim 1, 2, or 3,
The control device for an internal combustion engine, wherein the temperature of the intake passage injection valve is a temperature of a tip portion of the intake passage injection valve facing the intake passage. The control apparatus for an internal combustion engine according to claim 4,
The internal combustion engine control apparatus characterized in that the temperature of the tip portion of the intake passage injection valve is estimated based on the internal combustion engine coolant temperature and the fuel cut duration when the fuel cut release condition is satisfied. . The control device for an internal combustion engine according to claim 1 or 2,
An electric motor is connected to the drive shaft of the internal combustion engine, and the internal combustion engine is stopped when the temperature of the intake passage injection valve reaches the fuel vapor generation temperature when the fuel cut cancellation condition is satisfied. In this case, the control of the internal combustion engine is characterized in that the fuel injection from the intake passage injection valve is prohibited and the drive shaft of the internal combustion engine is rotated by the electric motor so that air is circulated through the intake passage. apparatus. The control device for an internal combustion engine according to claim 1 or 2,
Applied to the vehicle,
The internal combustion engine and a generator motor are provided as the driving source for traveling, and operation in a regeneration mode in which regenerative power generation by the generator motor is performed during vehicle deceleration is possible.
A control apparatus for an internal combustion engine, wherein when the fuel cut cancellation condition is satisfied, a throttle valve provided in an intake passage is opened in the regeneration mode.

Images