JP2013238140A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine which can inhibit lowering of drivability and deterioration of fuel economy caused by stopping fuel supply of the internal combustion engine after attenuation of an output torque of the internal combustion engine.SOLUTION: An EG-ECU (electronic control unit for engine): calculates the smallest natural number n satisfying n>TQsub/(Tu×θa) using difference torque TQsub, natural vibration period Tu of a power transmission system and limit attenuation rate θa, under a condition that an attenuation rate ΔTQ is a limit attenuation rate θa or more (Step S7); calculates the largest natural number n satisfying n≤TQsub/(Tu×θb) using difference torque TQsub, natural vibration period Tu and the smallest allowable attenuation rate θb, under a condition that an attenuation rate ΔTQ is less than the smallest allowable attenuation rate θb (Step S8); calculates a time Tr (=Tu×n) over which an output torque of an engine 2 is attenuated (Step S9); and calculates an attenuation rate ΔTQ (=TQsub/Tr) at which an output torque of the engine 2 is attenuated (Step S10).

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, in a vehicle equipped with an internal combustion engine as a power source, for the purpose of improving fuel consumption, when the output torque of the internal combustion engine is not required, such as during deceleration, a fuel cut that stops the supply of fuel to the internal combustion engine The thing provided with the control apparatus which performs is known.

  In such a vehicle, when a fuel cut is executed, the difference between the output torque output from the internal combustion engine before the fuel cut is executed and the output torque output from the internal combustion engine after the fuel cut is executed is A shock will occur.

  As a control device for an internal combustion engine for suppressing such a vehicle shock, a fuel cut means for cutting fuel supply to the internal combustion engine when a predetermined deceleration operation condition is satisfied, and a start of fuel cut by the fuel cut means are delayed by a predetermined time There has been known a fuel cut delay means for causing ignition timing retarding means for retarding the ignition timing during the fuel cut delay time (see, for example, Patent Document 1).

  With this configuration, the conventional control device for an internal combustion engine disclosed in Patent Document 1 attenuates the output torque of the internal combustion engine by retarding the ignition timing before executing the fuel cut, thereby reducing the fuel cut. The difference between the output torque output from the internal combustion engine before execution and the output torque output from the internal combustion engine after execution of fuel cut is reduced, and the occurrence of shock in the vehicle is suppressed.

Japanese Patent Laid-Open No. 10-030477

  However, the conventional control device for an internal combustion engine as described in Patent Document 1 does not consider the attenuation rate when the output torque of the internal combustion engine is attenuated. More specifically, when the output torque of the internal combustion engine is attenuated and fuel is no longer supplied to the internal combustion engine, the torsional torque of the power transmission system interposed between the internal combustion engine and the drive wheels is released. As a result, torsional vibration may occur in the power transmission system.

  This torsional vibration may cause so-called squealing in which the vehicle vibrates in the front-rear direction, which may reduce drivability. This scuffing can be suppressed by attenuating the output torque of the internal combustion engine over a natural number times the natural period of the power transmission system and then releasing the torsional torque of the power transmission system.

  However, if the damping rate of the output torque of the internal combustion engine is made too high, the damping rate of the output torque of the internal combustion engine changes abruptly when fuel is no longer supplied to the internal combustion engine depending on the running state of the vehicle. As a result, the vehicle may be shocked and drivability may be reduced. On the other hand, if the damping rate of the output torque of the internal combustion engine is made too low, it takes time until the fuel cut is executed, so that the fuel consumption may be deteriorated.

  As described above, the conventional control device for an internal combustion engine reduces drivability or deteriorates fuel consumption by stopping the fuel supply of the internal combustion engine after the output torque of the internal combustion engine is attenuated. There was a problem that it sometimes happened.

  The present invention has been made to solve such a problem. The drivability is deteriorated and the fuel consumption is deteriorated and the fuel consumption is deteriorated by stopping the fuel supply of the internal combustion engine after the output torque of the internal combustion engine is attenuated. It is an object of the present invention to provide a control device for an internal combustion engine that can suppress the engine.

  In order to achieve the above object, the control device for an internal combustion engine of the present invention is (1) a predetermined control device for an internal combustion engine that stops the fuel supply to the internal combustion engine after the output torque of the internal combustion engine is attenuated. Decreases the output torque of the internal combustion engine to the target torque over a natural number of times the natural vibration period of the power transmission system interposed between the internal combustion engine and the drive wheels at a damping rate within the range. The output torque attenuation means for executing the output torque attenuation control is provided.

  With this configuration, the control device for an internal combustion engine according to the present invention drives the internal combustion engine at a damping rate within a predetermined range so as not to cause a shock to the vehicle and not to fall below a predetermined minimum allowable damping rate. An internal combustion engine that suppresses the squealing without causing a shock to the vehicle by attenuating the output torque of the internal combustion engine over a natural number times the natural vibration period of the power transmission system interposed between the wheels and the vehicle. It is possible to suppress a decrease in drivability and a deterioration in fuel consumption due to stopping the fuel supply of the internal combustion engine after the output torque of the engine is attenuated.

  In the control apparatus for an internal combustion engine according to (1), (2) the output torque attenuation means is configured to shock the vehicle when the attenuation rate is significantly reduced when the attenuation rate of the output torque of the internal combustion engine is significantly reduced. The output torque damping control is executed by taking the shortest time that is a natural number multiple of the natural vibration period of the power transmission system at a damping rate lower than the critical damping rate, provided that the critical damping rate is greater than You may make it do.

  With this configuration, the control device for an internal combustion engine according to the present invention takes a natural number of times the natural vibration period of the power transmission system interposed between the internal combustion engine and the drive wheels at a damping rate that does not cause a shock to the vehicle. By damping the output torque of the internal combustion engine, it is possible to suppress the squealing without causing a shock to the vehicle.

  Further, in the control device for an internal combustion engine according to the above (1) or (2), (3) the output torque attenuation means is provided on the condition that the attenuation rate is less than a predetermined minimum allowable attenuation rate. The output torque attenuation control may be executed by taking a longest time that is a natural number multiple of the natural vibration period of the power transmission system at a damping rate equal to or greater than the minimum allowable damping rate.

  With this configuration, the control device for an internal combustion engine according to the present invention can prevent the time taken to execute the fuel cut.

  Further, in the control device for an internal combustion engine according to any one of (1) to (3), (4) the output torque attenuating means is changed from a driving state that generates a driving force to a driven state that receives the driving force. In the operation state switching period including the section in which the operation state of the internal combustion engine is switched, the attenuation rate of the output torque of the internal combustion engine may be decreased to a level that does not become negative.

  With this configuration, the control apparatus for an internal combustion engine according to the present invention reduces the output torque attenuation rate of the internal combustion engine to a level that does not become negative, so that the power is increased when the operating state of the internal combustion engine is switched from the driving state to the driven state. In order to prevent a shock generated in the transmission system, it is possible to suppress a decrease in drivability.

  Further, in the control device for an internal combustion engine according to the above (4), (5) when the output torque attenuation means starts to attenuate the output torque of the internal combustion engine, it starts to attenuate the output torque of the internal combustion engine. From the output torque of the internal combustion engine, the output torque attenuation control may be executed using the torque at the start of the operation state switching period as the target torque.

  With this configuration, the control device for an internal combustion engine according to the present invention drives the internal combustion engine at a damping rate within a predetermined range so as not to cause a shock to the vehicle and not to fall below a predetermined minimum allowable damping rate. Since the output torque of the internal combustion engine is attenuated over a natural number of times the natural vibration period of the power transmission system interposed between the wheels, the output torque attenuation rate of the internal combustion engine is greatly reduced during the operation state switching period. This makes it possible to suppress the occurrence of squealing without causing a shock to the vehicle, and to suppress deterioration of fuel consumption.

  Further, in the control device for an internal combustion engine according to the above (4) or (5), (6) the output torque attenuation means is configured to calculate the internal combustion engine from an output torque of the internal combustion engine at the end of the operation state switching period. The output torque attenuation control may be executed with the torque of the internal combustion engine when stopping the fuel supply to the target torque as the target torque.

  With this configuration, the control device for an internal combustion engine according to the present invention drives the internal combustion engine at a damping rate within a predetermined range so as not to cause a shock to the vehicle and not to fall below a predetermined minimum allowable damping rate. In order to attenuate the output torque of the internal combustion engine over a natural number of times the natural vibration period of the power transmission system intervening between the wheels, the vehicle is shocked by the sneezing that occurs when the fuel supply to the internal combustion engine is stopped. It can suppress without producing and can suppress the deterioration of a fuel consumption.

  Further, in the control device for an internal combustion engine according to any one of (1) to (6), (7) the output torque attenuation means is configured to determine an intake air amount and an ignition timing for the internal combustion engine based on the attenuation rate. At least one of them may be varied.

  With this configuration, the control device for an internal combustion engine of the present invention can adjust the attenuation rate of the output torque of the internal combustion engine.

  According to the present invention, it is possible to provide a control device for an internal combustion engine that can suppress a decrease in drivability and a deterioration in fuel consumption caused by stopping the fuel supply of the internal combustion engine after the output torque of the internal combustion engine is attenuated. it can.

1 is a functional block diagram showing a configuration of a vehicle equipped with a control device for an internal combustion engine according to an embodiment of the present invention. It is a schematic sectional drawing of the engine shown in FIG. It is a schematic perspective view of the engine shown in FIG. FIG. 2 is a schematic diagram of the automatic transmission shown in FIG. 1. It is a graph for demonstrating the fuel cut by the electronic control unit for engines shown in FIG. It is a flowchart which shows the operation | movement of the output torque attenuation | damping control by the engine electronic control unit which comprises the control apparatus of the internal combustion engine which concerns on one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, an example in which the control device for an internal combustion engine according to the present invention is applied to an FR (Front engine Rear drive) vehicle equipped with an automatic transmission will be described.

  As shown in FIG. 1, a vehicle 1 according to the present embodiment includes an engine 2 constituting an internal combustion engine, a torque converter 3 that amplifies output torque output from the engine 2, and a rotational speed of an output shaft of the torque converter 3. The transmission mechanism 5 that rotates the output shaft 4 at the rotational speed obtained by shifting the transmission shaft 4, the differential gear 7 that transmits the rotational force of the output shaft 4 of the transmission mechanism 5 to the drive shafts 6 L and 6 R, and the drive shafts 6 L and 6 R are rotated. The driving wheels 8L and 8R that are driven by this are provided. Here, the torque converter 3 and the transmission mechanism 5 constitute an automatic transmission 9.

  Further, the vehicle 1 electrically connects an engine electronic control unit (hereinafter referred to as “EG-ECU”) 10 that controls the engine 2, a hydraulic control circuit 11 that controls the automatic transmission 9 by hydraulic pressure, and a hydraulic control circuit 11. And an automatic transmission electronic control unit (hereinafter referred to as “TM-ECU”) 12 that automatically controls.

  As shown in FIG. 2, the engine 2 includes a cylinder block 20, a cylinder head 21 fixed to the upper part of the cylinder block 20, and an oil pan 22 that stores oil, and the cylinder block 20, the cylinder head 21, Thus, a plurality of cylinders 23 are formed.

  In the present embodiment, the engine 2 is assumed to be an in-line 4-cylinder engine. However, in the present invention, the in-line 6-cylinder engine, the V-type 6-cylinder engine, the V-type 12-cylinder engine, or the horizontal You may be comprised by various types of engines, such as an opposed 6 cylinder engine. Note that the engine 2 shown in FIG. 2 shows one cylinder 23 among four cylinders arranged in series.

  A piston 24 is accommodated in the cylinder 23 so as to be able to reciprocate. A combustion chamber 25 of each cylinder 23 is formed by the cylinder block 20, the cylinder head 21, and the piston 24. In the present embodiment, the engine 2 is described as being constituted by a four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke while the piston 24 reciprocates twice. To do.

  Pistons 24 housed in the cylinders 23 are connected to a crankshaft 27 via connecting rods 26. The connecting rod 26 converts the reciprocating motion of the piston 24 into the rotational motion of the crankshaft 27.

  Therefore, the engine 2 reciprocates the piston 24 by burning the fuel / air mixture in the combustion chamber 25 and rotates the crankshaft 27 via the connecting rod 26, thereby supplying power to the torque converter 3. To communicate.

  In addition, although the fuel used for the engine 2 is gasoline, it may replace with gasoline and may be alcohol fuel which mixed alcohol and gasoline, such as hydrocarbon fuels, such as light oil, and ethanol.

  The engine 2 is provided with an intake pipe 30 connected to the cylinder head 21 for introducing air into the combustion chamber 25. The intake pipe 30 includes an air cleaner 31 that cleans air flowing from outside the vehicle, an air flow sensor 32 that detects a flow rate of air introduced into the combustion chamber 25, that is, an intake air amount, and a throttle valve that adjusts the intake air amount. 33 is provided.

  The air cleaner 31 is configured to remove foreign substances in the intake air by using, for example, a paper or synthetic fiber nonwoven fabric filter accommodated therein. The air flow sensor 32 is provided on the upstream side of the throttle valve 33 and outputs a detection signal indicating the intake air amount to the EG-ECU 10.

  The throttle valve 33 is constituted by a thin disc-like valve body, and includes a shaft at the center of the valve body. The throttle valve 33 is provided with a throttle valve actuator 34 that rotates the valve body by rotating the shaft in accordance with the control of the EG-ECU 10 and adjusts the intake air amount to the throttle valve 33.

  Further, the engine 2 is provided with an exhaust pipe 35 connected to the cylinder head 21 for discharging exhaust gas generated by combustion of the air-fuel mixture in the combustion chamber 25 to the outside of the vehicle. The exhaust pipe 35 is provided with a catalyst 36 for oxidation-reduction purification of harmful substances in the exhaust gas.

  The catalyst 36 generally includes a three-way catalyst that can efficiently remove harmful substances such as unburned hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) contained in the exhaust gas. Yes. As this three-way catalyst, a catalyst having a function of efficiently removing NOx even from exhaust gas having a high NOx content is preferably used.

  The cylinder block 20 is formed with a water jacket 37 through which cooling water circulates, and a water temperature sensor 38 that detects the temperature of the cooling water circulated through the water jacket 37. The cylinder head 21 is formed with an intake port 40 for communicating the intake pipe 30 and the combustion chamber 25 and an exhaust port 41 for communicating the combustion chamber 25 and the exhaust pipe 35.

  Further, the cylinder head 21 has an intake valve 42 for controlling the introduction of combustion air from the intake pipe 30 to the combustion chamber 25 and an exhaust valve for controlling the discharge of exhaust gas from the combustion chamber 25 to the exhaust pipe 35. An exhaust valve 43, an injector 44 for injecting fuel into the combustion chamber 25, and a spark plug 45 for igniting the air-fuel mixture in the combustion chamber 25 are provided.

  The injector 44 has a solenoid coil and a needle valve that are controlled by the EG-ECU 10. Fuel is supplied to the injector 44 at a predetermined pressure. When the solenoid coil is energized by the EG-ECU 10, the injector 44 opens the needle valve and injects fuel into the combustion chamber 25.

  The spark plug 45 is a known spark plug having an electrode made of platinum or an iridium alloy. The spark plug 45 is discharged when the electrode is energized by the EG-ECU 10 and ignites the air-fuel mixture in the combustion chamber 25.

  As shown in FIG. 3, the engine 2 is provided with an intake camshaft 50 and an exhaust camshaft 51 rotatably on the cylinder head 21. The intake camshaft 50 is provided with an intake cam 52 that contacts the upper end of the intake valve 42. When the intake camshaft 50 rotates, the intake cam 52 drives the intake valve 42 to open and close, so that the intake port 40 and the combustion chamber 25 are opened and closed.

  The exhaust camshaft 51 is provided with an exhaust cam 53 that contacts the upper end of the exhaust valve 43. When the exhaust camshaft 51 rotates, the exhaust cam 53 opens and closes the exhaust valve 43 so that the combustion chamber 25 and the exhaust port 41 are opened and closed.

  At one end of the intake camshaft 50, an intake cam sprocket 54 and an intake side rotation phase controller 55 that rotates the intake camshaft 50 relative to the intake cam sprocket 54 are provided.

  The intake side rotation phase controller 55 is controlled by the EG-ECU 10 to rotate the intake camshaft 50 forward or retarded with respect to the intake cam sprocket 54.

  An exhaust cam sprocket 56 and an exhaust side rotation phase controller 57 that rotates the exhaust cam shaft 51 relative to the exhaust cam sprocket 56 are provided at one end of the exhaust cam shaft 51.

  Further, the exhaust-side rotation phase controller 57 is controlled by the EG-ECU 10 to rotate the exhaust camshaft 51 forward or retarded with respect to the exhaust cam sprocket 56.

  A crank sprocket 58 is provided at one end of the crankshaft 27. A timing belt 59 is wound around the intake cam sprocket 54, the exhaust cam sprocket 56, and the crank sprocket 58. The timing belt 59 transmits the rotation of the crank sprocket 58 to the intake cam sprocket 54 and the exhaust cam sprocket 56.

  Accordingly, when the rotation of the crankshaft 27 is transmitted to the intake camshaft 50 and the exhaust camshaft 51 by the timing belt 59, the intake valve 42 and the exhaust valve 43 driven by the intake camshaft 50 and the exhaust camshaft 51 are The intake port 40 and the exhaust port 41 are opened and closed in synchronization with the crankshaft 27, respectively. The intake camshaft 50 and the exhaust camshaft 51 make one round while the crankshaft 27 makes two rounds.

  The crankshaft 27 is provided with a crank rotor 60 that rotates together with the crankshaft 27. The engine 2 includes a crank angle sensor 61 for detecting the rotation angle of the crank rotor 60.

  The crank angle sensor 61 is configured by an MRE sensor having a magnetic resistance element (MRE). When the crankshaft 27 rotates, the direction of the magnetic field applied to the crank angle sensor 61, that is, the magnetic vector, changes due to the crests and valleys of the teeth provided in the crank rotor 60, and the internal resistance value changes.

  The crank angle sensor 61 generates a crank angle signal shaped into a rectangular wave that takes a high state and a low state by comparing a waveform output after converting the change in resistance value into a voltage and a threshold value. The generated crank angle signal is output to the EG-ECU 10.

  As shown in FIG. 4, the torque converter 3 includes a pump impeller 71 connected to the crankshaft 27 of the engine 2 via the input shaft 70, and an output shaft 72 constituting a part of the input shaft of the transmission mechanism 5. And a stator impeller 75 that is prevented from rotating in one direction by a one-way clutch 74. Here, the pump impeller 71 and the turbine impeller 73 transmit power through a fluid.

  The torque converter 3 has a lockup clutch 76 for directly connecting the pump impeller 71 and the turbine impeller 73. The lock-up clutch 76 holds the front cover (not shown) with hydraulic oil when the vehicle 1 is traveling at a high speed and the like, and takes an engaged state in which the pump impeller 71 and the turbine impeller 73 are mechanically directly connected. Compared with a released state in which the impeller 71 and the turbine impeller 73 are mechanically released, the power transmission efficiency from the engine 2 to the speed change mechanism 5 is increased.

  The pump impeller 71 is provided with a mechanical oil pump 77 that generates a hydraulic pressure for controlling the transmission of the transmission mechanism 5 and a hydraulic pressure for supplying lubricating oil to each part.

  The speed change mechanism 5 includes a first planetary gear device 78, a second planetary gear device 79, and a third planetary gear device 80. The sun gear S1 of the first planetary gear device 78 can be connected to the input shaft via the clutch C3 and can be connected to the housing 81 via the one-way clutch F2 and the brake B3.

  The carrier CA1 of the first planetary gear device 78 can be connected to the housing 81 via the brake B1. The ring gear R1 of the first planetary gear device 78 is connected to the ring gear R2 of the second planetary gear device 79, and can be connected to the housing 81 via the brake B2.

  The sun gear S2 of the second planetary gear device 79 is connected to the sun gear S3 of the third planetary gear device 80, and can be connected to the input shaft via the clutch C4. The sun gear S2 can be connected to the input shaft via the one-way clutch F4 and the clutch C1.

  The carrier CA2 of the second planetary gear unit 79 is coupled to the ring gear R3 of the third planetary gear unit 80, and can be coupled to the input shaft via the clutch C2 and to the housing 81 via the brake B4. It has become.

  The carrier CA2 is prevented from rotating in the direction opposite to the rotation direction of the input shaft by a one-way clutch F3 provided in parallel with the brake B4. Further, the carrier CA3 of the third planetary gear device 80 is connected to the output shaft 4.

  The clutches C1 to C4 and the brakes B1 to B4 are configured by a hydraulic friction engagement device that is controlled to be engaged by a hydraulic actuator, such as a multi-plate clutch or brake.

  The hydraulic control circuit 11 includes transmission solenoids S1 to S4 and linear solenoids SLT and SLU. The transmission solenoid S1 is operated at the time of shifting from the first speed to the second speed. The transmission solenoid S2 is operated at the time of shifting from the 2nd speed to the 3rd speed and at the time of shifting from the 5th speed to the 6th speed.

  The transmission solenoid S3 is operated when shifting from the third speed to the fourth speed. The transmission solenoid S4 is operated at the time of shifting from the fourth speed to the fifth speed.

  The linear solenoid SLT performs line pressure control and back pressure control of an accumulator (not shown). The linear solenoid SLU mainly controls the state of the lockup clutch 76.

  As described above, the clutches C1 to C4 and the brakes B1 to B4 are engaged according to the hydraulic circuit that is switched according to the excitation state or non-excitation of the transmission solenoids S1 to S4 and the linear solenoids SLT and SLU or the operating state of the manual valve (not shown). One of the state and the release state is assumed.

  That is, the speed change mechanism 5 is configured to take a gear position according to the combination of the engaged state and the released state of the clutches C1 to C4 and the brakes B1 to B4. In the present embodiment, the speed change mechanism 5 is assumed to form any one of six forward speeds and one reverse speed that is composed of first to sixth speeds.

  In FIG. 1, an EG-ECU 10 is a microprocessor that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a flash memory, and an input / output port (not shown). It is configured.

  A program for causing the microprocessor to function as the EG-ECU 10 is stored in the ROM of the EG-ECU 10. That is, the CPU of the EG-ECU 10 functions as the EG-ECU 10 by executing a program stored in the ROM using the RAM as a work area.

  In the present embodiment, on the input side of the EG-ECU 10, in addition to the crank angle sensor 61, the airflow sensor 32, and the water temperature sensor 38, an accelerator opening sensor 91 that detects an accelerator opening representing the opening of the accelerator pedal 90 is provided. Are connected to a vehicle speed sensor 92 for detecting the vehicle speed.

  The accelerator opening sensor 91 is configured by, for example, an electronic position sensor using a Hall element. When the accelerator pedal 90 is operated by the driver, the accelerator opening sensor 91 outputs a signal indicating the accelerator opening indicating the opening of the accelerator pedal 90 to the EG-ECU 10. The vehicle speed sensor 92 detects the rotation angles of the drive shafts 6L and 6R, averages the detected rotation angles of the drive shafts 6L and 6R, and outputs the average to the EG-ECU 10.

  The EG-ECU 10 communicates with other ECUs such as the TM-ECU 12 via the high-speed CAN, and exchanges various control signals and data with the other ECUs such as the TM-ECU 12. .

  For example, the EG-ECU 10 controls the fuel injection control for the injector 44, the ignition control for the spark plug 45, and the intake air amount for the throttle valve actuator 34 based on detection signals input from various sensors that detect the operating state of the engine 2. While performing operation control of the engine 2 such as adjustment control, data related to the operation state of the engine 2 is output to the TM-ECU 12 as necessary.

  Further, the EG-ECU 10 controls the intake side rotational phase controller 55 and the exhaust cam sprocket 56 to adjust the opening / closing timing of the intake valve 42 and the exhaust valve 43 according to the operating state of the engine 2. Control is to be executed.

  The TM-ECU 12 is configured by a microprocessor that includes a CPU, a ROM, a RAM, a flash memory, and an input / output port (not shown). A program for causing the microprocessor to function as the TM-ECU 12 is stored in the ROM of the TM-ECU 12.

  That is, the CPU of the TM-ECU 12 functions as the TM-ECU 12 by executing a program stored in the ROM using the RAM as a work area.

  In the present embodiment, a shift position sensor 94 that detects the shift position selected by the shift lever 93 is connected to the input side of the TM-ECU 12.

  The TM-ECU 12 communicates with other ECUs such as the EG-ECU 10 via the high-speed CAN, and exchanges various control signals and data with the other ECUs such as the EG-ECU 10. .

  For example, the TM-ECU 12 controls the hydraulic control circuit 11 based on the shift position detected by the shift position sensor 94 and the operating state of the engine 2 output from the EG-ECU 10, so Are formed, and information representing the speed stage formed in the speed change mechanism 5 is output to the EG-ECU 10.

  Hereinafter, the fuel cut executed by the EG-ECU 10 in the present embodiment will be described. The EG-ECU 10 executes a fuel cut that stops the fuel supply to the engine 2 after the output torque of the engine 2 is attenuated. The EG-ECU 10 constitutes output torque attenuation means in the present invention.

  Specifically, as shown in FIG. 5, the EG-ECU 10 is predetermined when the accelerator pedal position sensor 91 detects that the opening degree of the accelerator pedal 90 is 0, that is, the accelerator is OFF, at time t0. The output torque of the engine 2 is estimated at a delay section, for example, at time t1 when about 100 ms to 200 ms have elapsed.

  Here, the ROM of the EG-ECU 10 has a map in which the output torque of the engine 2 is previously associated with the engine rotation speed, the intake air amount, and the ignition timing for the spark plug 45 by experiments. Stored.

  The EG-ECU 10 corresponds to a map with respect to the engine speed of the engine 2 obtained from the signal output from the crank angle sensor 61, the intake air amount obtained from the air flow sensor 32, and the ignition timing for the spark plug 45. By specifying the attached output torque of the engine 2, the current output torque of the engine 2 (hereinafter referred to as “current torque TQc”) is estimated.

  Further, the EG-ECU 10 attenuates the output torque of the engine 2 so that the operating state of the engine 2 is changed from a driving state that generates driving force to a driven state that receives a driving force such as the inertial force of the vehicle 1. The output torque of the engine 2 to be switched (hereinafter referred to as “drive switching torque TQex”) is estimated.

  Here, the ROM of the EG-ECU 10 stores the vehicle speed, the gear stage formed in the transmission mechanism 5, auxiliary loads such as an air conditioner, alternator and oil pump, and the coolant temperature of the engine 2. Thus, a map in which the drive switching torque TQex is previously correlated by experiment is stored.

  The EG-ECU 10 includes a vehicle speed of the vehicle 1 obtained from the vehicle speed sensor 92, a gear stage formed in the transmission mechanism 5 obtained from the TM-ECU 12, an auxiliary machine load corresponding to the operating state of each auxiliary machine, and a water temperature sensor. The drive switching torque TQex is estimated by specifying the drive switching torque TQex associated with the map with respect to the water temperature obtained from 38.

  At time t1, the EG-ECU 10 sets the output torque of the engine 2 as the current torque with the torque TQex + TQm that is higher than the drive switching torque TQex by a minute torque TQm that is a predetermined number N · m as a target torque. It is designed to attenuate from TQc.

  Specifically, the EG-ECU 10 has a damping rate ΔTQ within a predetermined range R and is a natural number times the natural vibration period Tu of the power transmission system interposed between the engine 2 and the drive wheels 8L and 8R. Over time, the output torque attenuation control for attenuating the output torque of the engine 2 from the current torque TQc to the target torque TQt is executed. Here, the natural vibration period Tu of the power transmission system interposed between the engine 2 and the drive wheels 8 </ b> L and 8 </ b> R is determined in advance for each shift stage formed in the transmission mechanism 5 by experiments.

  The predetermined range R is from the limit attenuation rate θa to the minimum allowable attenuation rate θb. The limit damping rate θa is a damping rate at which a shock starts to occur in the vehicle 1 when the damping rate of the output torque of the engine 2 is significantly reduced, and is determined in advance by experiments.

  That is, when the output torque of the engine 2 is attenuated with an attenuation rate equal to or greater than the limit attenuation rate θa, a shock is generated in the vehicle 1 when the attenuation rate of the output torque of the engine 2 is significantly reduced.

  On the other hand, the minimum allowable attenuation rate θb is a guard value of a predetermined attenuation rate ΔTQ. That is, when the output torque of the engine 2 is attenuated with an attenuation rate less than the minimum allowable attenuation rate θb, the time until the output torque of the engine 2 reaches the target torque becomes longer than a predetermined allowable time.

  More specifically, the EG-ECU 10 takes the time multiplied by the natural vibration period Tu of the power transmission system interposed between the engine 2 and the drive wheels 8L and 8R and a predetermined natural number N, The attenuation rate ΔTQ for attenuating the output torque 2 from the current torque TQc to the target torque TQt is calculated.

  Here, the EG-ECU 10 transmits power that is interposed between the engine 2 and the drive wheels 8L and 8R at a damping rate lower than the limiting damping rate θa on condition that the damping rate ΔTQ is equal to or higher than the limiting damping rate θa. The output torque of the engine 2 is attenuated from the current torque TQc to the target torque TQt over the shortest time that is a natural number times the natural vibration period Tu of the system.

  Further, the EG-ECU 10 provides power that is interposed between the engine 2 and the drive wheels 8L and 8R at a damping rate equal to or greater than the minimum allowable damping rate θb on condition that the damping rate ΔTQ is less than the minimum allowable damping rate θb. The output torque of the engine 2 is attenuated from the current torque TQc to the target torque TQt over the longest time that is a natural number times the natural vibration period Tu of the transmission system.

  In the present embodiment, the EG-ECU 10 attenuates the output torque of the engine 2 by changing the intake air amount and ignition timing for the engine 2 as shown in FIG.

  Further, the EG-ECU 10 executes output torque attenuation control at time t1, and when the output torque of the engine 2 reaches the target torque at time t2, the output torque of the engine 2 is attenuated during a predetermined operation state switching period. The rate is reduced to a level that does not become negative.

  Here, the driving state switching period includes a period in which the driving state of the engine 2 is switched from a driving state in which driving force is generated to a driven state in which driving force such as inertial force of the vehicle 1 is received. In the operation state switching period, the EG-ECU 10 attenuates the output torque of the engine 2 from the torque TQex + TQm that is higher than the drive switching torque TQex by a minute torque TQm to the torque TQex-TQm that is lower than the drive switching torque TQex by a smaller torque TQm. It is like that.

  Further, the EG-ECU 10 attenuates the output torque of the engine 2 at time t2, and when the output torque of the engine 2 becomes torque TQex-TQm at time t3, the torque TQfc of the engine 2 when the fuel supply to the engine 2 is stopped. The output torque attenuation control is executed with the target torque as the target torque.

  Further, the EG-ECU 10 executes output torque attenuation control at time t3, and controls the injector 44 so that fuel is not injected when the output torque of the engine 2 reaches the target torque at time t4.

  As described above, the EG-ECU 10 executes the output torque attenuation control from the time t1 to the time t2, so that the output torque attenuation rate of the engine 2 is reduced during the operation state switching period from the time t2 to the time t3. It is configured to suppress the squealing that occurs due to a significant decrease so that the vehicle 1 is not shocked and does not fall below a predetermined minimum allowable attenuation rate θb.

  Further, the EG-ECU 10 switches the operating state of the engine 2 from the driving state to the driven state by significantly reducing the attenuation rate of the output torque of the engine 2 during the driving state switching period from the time t2 to the time t3. It is configured to prevent shocks that sometimes occur in the power transmission system.

  Further, the EG-ECU 10 generates a shock in the vehicle 1 due to the squealing generated by stopping the fuel injection by the injector 44 at time t4 by executing output torque attenuation control from time t3 to time t4. And is configured not to fall below a predetermined minimum allowable attenuation rate θb.

  Next, the operation in the output torque attenuation control by the EG-ECU 10 will be described with reference to the flowchart shown in FIG. The operation in the output torque attenuation control shown in the flowchart shown in FIG. 6 starts at time t1 and time t3 shown in FIG.

  First, the EG-ECU 10 calculates a damping rate ΔTQ (= Tu × N) for attenuating the output torque of the engine 2 (step S1), estimates the current torque TQc (step S2), and determines the target torque TQt. (Step S3).

  Next, the EG-ECU 10 calculates a difference between the target torque TQt and the current torque TQc, that is, a differential torque TQsub obtained by subtracting the target torque TQt from the current torque TQc (step S4).

  Here, the EG-ECU 10 determines whether or not the attenuation rate ΔTQ is equal to or greater than the limit attenuation rate θa (step S5), and when determining that the attenuation rate ΔTQ is not equal to or greater than the limit attenuation rate θa, the attenuation rate ΔTQ. Is less than the minimum allowable attenuation rate θb (step S6). Here, if the EG-ECU 10 determines that the damping rate ΔTQ is not less than the minimum allowable damping rate θb, the EG-ECU 10 skips the output torque damping control until step S11.

  In step S5, when the EG-ECU 10 determines that the damping rate ΔTQ is greater than or equal to the limit damping rate θa, the differential torque TQsub and the power transmission system interposed between the engine 2 and the drive wheels 8L and 8R. The minimum natural number n satisfying n> TQsub / (Tu × θa) is calculated using the natural vibration period Tu and the limit damping rate θa (step S7).

  In step S6, if the EG-ECU 10 determines that the attenuation rate ΔTQ is less than the minimum allowable attenuation rate θb, the differential torque TQsub and the power interposed between the engine 2 and the drive wheels 8L and 8R. The maximum natural number n satisfying n ≦ TQsub / (Tu × θb) is calculated using the natural vibration period Tu of the transmission system and the minimum allowable damping rate θb (step S8).

  When the natural number n is calculated, the EG-ECU 10 calculates a time Tr (= Tu × n) for attenuating the output torque of the engine 2 (step S9), and an attenuation rate ΔTQ (= TQsub / Tr) is calculated (step S10).

  The EG-ECU 10 attenuates the output torque of the engine 2 by the attenuation rate ΔTQ calculated in this way (step S11), and when the output torque of the engine 2 reaches the target torque TQt, the output torque attenuation control is completed.

  As described above, the control apparatus for an internal combustion engine according to the embodiment of the present invention does not cause a shock to the vehicle 1 and does not fall below a predetermined minimum allowable attenuation rate θb. The output torque of the engine 2 is attenuated over a natural number of times the natural vibration period Tu of the power transmission system interposed between the engine 2 and the drive wheels 8L and 8R with the damping rate ΔTQ of the vehicle 1. Therefore, it is possible to suppress a decrease in drivability and a deterioration in fuel consumption caused by stopping the fuel supply to the engine 2 after the output torque of the engine 2 is attenuated in order to suppress the squealing without causing a shock.

  In the present embodiment, EG-ECU 10 has been described as attenuating the output torque of engine 2 by varying the intake air amount and ignition timing for engine 2, but in the present invention, EG-ECU 10 The output torque of the engine 2 may be attenuated by changing either the intake air amount or the ignition timing for the engine 2.

  In the present embodiment, the example in which the control device for an internal combustion engine according to the present invention is applied to a vehicle having an automatic transmission has been described. However, the control device for an internal combustion engine according to the present invention includes a manual transmission. The present invention may be applied to a vehicle having a continuously variable transmission.

  In the present embodiment, the example in which the control device for an internal combustion engine according to the present invention is applied to an FR vehicle has been described. However, the control device for an internal combustion engine according to the present invention is applied to an FF (Front engine Front drive) vehicle. Alternatively, it may be applied to a four-wheel drive vehicle.

  Moreover, in this Embodiment, although the example which applied the gasoline engine which uses gasoline as a fuel as an internal combustion engine which concerns on this invention was demonstrated, you may apply a diesel engine as an internal combustion engine which concerns on this invention.

  When a diesel engine is applied as the internal combustion engine according to the present invention, the EG-ECU 10 is configured to attenuate the output torque of the engine 2 by changing the fuel injection amount to the engine 2.

  The control device for an internal combustion engine according to the present invention may be applied to a power split type hybrid vehicle. In this case, the output torque of the engine 2 is attenuated by changing the power consumed by the rotating electrical machine to which the power generated by the engine 2 is distributed.

  Further, in the present embodiment, the EG-ECU 10 is based on a map in which the output torque of the engine 2 is associated with the engine speed of the engine 2, the intake air amount, and the ignition timing for the spark plug 45. In the above description, the output torque of the engine 2 is estimated.

  On the other hand, the EG-ECU 10 according to the present invention removes a part of the exhaust gas in the exhaust pipe 35 in addition to the engine speed of the engine 2, the intake air amount, and the ignition timing for the spark plug 45. A map in which the output torque of the engine 2 is associated with at least one of the EGR rate in the EGR (Exhaust Gas Recirculation) device, the water temperature obtained from the water temperature sensor 38, and the phase angle in the VVT control. Based on this, the output torque of the engine 2 may be estimated.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the control apparatus for an internal combustion engine according to the present invention can suppress a decrease in drivability and a deterioration in fuel consumption caused by stopping the fuel supply to the internal combustion engine after the output torque of the internal combustion engine is attenuated. It is useful for a control device for an internal combustion engine that stops the fuel supply to the internal combustion engine after the output torque of the internal combustion engine is attenuated.

2 Engine (Internal combustion engine)
8L, 8R Drive wheel 10 EG-ECU (output torque attenuation means)

Claims (7)

In the control device for an internal combustion engine that stops the fuel supply to the internal combustion engine after the output torque of the internal combustion engine is attenuated,
Targeting the output torque of the internal combustion engine over a time that is a natural number times the natural vibration period of the power transmission system interposed between the internal combustion engine and the drive wheels, with a damping rate within a predetermined range An internal combustion engine control device comprising output torque attenuation means for executing output torque attenuation control for attenuation to a target torque.   The output torque attenuating means is configured so that the damping rate is equal to or greater than a limiting damping rate at which a shock starts to occur in a vehicle when the damping rate of the output torque of the internal combustion engine is significantly reduced. 2. The control device for an internal combustion engine according to claim 1, wherein the output torque damping control is executed by taking a shortest time that is a natural number times the natural vibration period of the power transmission system at a lower damping rate.   The output torque damping means is a natural number multiple of the natural vibration period of the power transmission system with a damping rate equal to or greater than the minimum allowable damping rate, provided that the damping rate is less than a predetermined minimum allowable damping rate. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the output torque attenuation control is executed over the longest time.   The output torque attenuating means is configured to reduce the output torque of the internal combustion engine during an operation state switching period including a period in which the operation state of the internal combustion engine is switched from a driving state that generates driving force to a driven state that receives driving force. The internal combustion engine control apparatus according to any one of claims 1 to 3, wherein the controller is lowered to a level that does not become negative.   When the output torque attenuation means starts to attenuate the output torque of the internal combustion engine, the torque at the start of the operation state switching period is determined from the output torque of the internal combustion engine at the start of attenuation of the output torque of the internal combustion engine. The control apparatus for an internal combustion engine according to claim 4, wherein the output torque attenuation control is executed with the target torque as the target torque.   The output torque attenuation means uses the output torque of the internal combustion engine when the fuel supply to the internal combustion engine is stopped as the target torque from the output torque of the internal combustion engine at the end of the operation state switching period as the target torque attenuation. 6. The control device for an internal combustion engine according to claim 4, wherein the control is executed.   The claim according to any one of claims 1 to 6, wherein the output torque attenuation means varies at least one of an intake air amount and an ignition timing with respect to the internal combustion engine based on the attenuation rate. The internal combustion engine control device described.

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