JP2014066227A - Control unit for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of knocking in a vehicle having an idling stop system and a vehicle having a control unit which cuts fuel in deceleration.SOLUTION: When an ECU serving as a control unit for an internal combustion engine mounted on a vehicle and capable of changing an opening timing and a closing timing of an intake valve, cuts fuel in a case in which an engine temperature exceeds a predetermined value (S2, S3), the opening timing of the intake valve is lagged (S4).

Description

  The present invention relates to a control device that controls an internal combustion engine mounted on a vehicle and capable of changing the opening / closing timing of an intake valve.

  2. Description of the Related Art An idling stop system that improves fuel efficiency by stopping idle rotation of an internal combustion engine when a vehicle is temporarily stopped, such as waiting for a signal, is well known. In the idling stop system, the internal combustion engine is automatically stopped when various conditions such as the vehicle speed is equal to or lower than a predetermined value, the brake pedal is depressed, the coolant temperature and the battery voltage are sufficiently high, that is, the idle stop condition is satisfied. (For example, see Patent Document 1).

  By the way, if the internal combustion engine is stopped by the conventional idling stop system and then restarted in a state where the engine temperature of the internal combustion engine is high, there is a problem that knocking is likely to occur. This problem is the same as when the cylinder is filled with air and the throttle valve is fully opened while the internal combustion engine is stopped, and the piston lowers because the rotational speed is low especially at the first cycle when restarting. This is because it takes time and the air-fuel mixture may be compressed and self-ignited when a spark occurs.

  The problems as described above are not limited to vehicles equipped with an idling stop system, but can occur in the same way even when a vehicle is equipped with a control device that performs fuel cut during deceleration or the like.

JP 2012-117413 A

  The present invention pays attention to the above points, and an object thereof is to suppress the occurrence of knocking in a vehicle equipped with an idling stop system or a vehicle equipped with a control device that cuts fuel during deceleration.

  In order to solve the above problems, the control apparatus for an idle stop vehicle according to the present invention performs the following control. That is, one of the control devices for an internal combustion engine according to the present invention controls an internal combustion engine mounted on a vehicle and capable of changing the opening / closing timing of an intake valve, and the fuel in the case where the engine temperature is equal to or higher than a predetermined value. When performing the cut, control is performed to retard the opening timing of the intake valve.

  Another aspect of the control device for an internal combustion engine according to the present invention is a control device that performs idling stop for stopping idling of an internal combustion engine mounted on a vehicle and capable of changing the opening / closing timing of an intake valve. Control is performed to retard the opening timing of the intake valve when the fuel injection is stopped to stop and the internal combustion engine is rotating inertially.

  If such control is performed, by delaying the opening timing of the intake valve, the pressure in the cylinder becomes negative during the period from the exhaust top dead center to the opening of the intake valve. As a result of adiabatic expansion, the temperature in the cylinder and the temperature of the cylinder block forming the inner wall of the cylinder are reduced, so that the occurrence of knocking is suppressed.

  In the present invention, “when performing fuel cut” is a concept that indicates an overall operating state in which fuel injection is not performed. Specifically, fuel injection is performed when performing an idle stop or during deceleration. This is a concept that includes the case of performing fuel cut control that is not performed.

  In such an internal combustion engine, when the intake air temperature is low, the temperature in the cylinder and the cylinder block may be excessively lowered and startability may deteriorate, but if the intake air temperature is below a predetermined temperature, the intake valve The occurrence of such a problem can be suppressed as long as the control is performed so as not to retard the valve opening timing.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of knocking can be suppressed in the vehicle provided with the idling stop system and the vehicle provided with the control apparatus which performs a fuel cut at the time of deceleration.

1 is a schematic configuration diagram of an internal combustion engine in an embodiment of the present invention. Schematic which shows the variable valve timing mechanism which the control apparatus of the embodiment controls. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment implements.

  FIG. 1 shows an outline of an internal combustion engine for a vehicle. The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream. An intake valve 35 is arranged in the intake port. The intake valve 35 is urged toward the valve closing side by a valve spring.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4. An exhaust valve 40 is disposed in the exhaust port. The exhaust valve 40 is biased toward the valve closing side by a valve spring.

  As shown in FIG. 2, in the internal combustion engine in the present embodiment, a timing chain 74 is wound around the crank sprocket 71, the intake side sprocket 72, and the exhaust side sprocket 73, and the rotation caused from the crankshaft is caused by this timing chain 74. The driving force is transmitted to the intake camshaft 63 via the intake side sprocket 72 and to the exhaust camshaft 64 via the exhaust side sprocket 73.

  In addition, a variable valve timing mechanism 6 is interposed between the intake side sprocket 72 and the intake camshaft. The variable valve timing mechanism 6 in the present embodiment changes the opening / closing timing of the intake valve by changing the rotational phase of the intake camshaft with respect to the crankshaft.

  The housing 61 of the variable valve timing mechanism 6 is fixed to the intake side sprocket 72, and the intake side sprocket 72 and the housing 61 are integrally rotated in synchronization with the crankshaft. On the other hand, the rotor 62 fixed to one end portion of the intake camshaft is housed in the housing 61 and can rotate relative to the intake-side sprocket 72 and the housing 61. A plurality of fluid chambers into which hydraulic fluid flows in and out are formed inside the housing 61, and each fluid chamber is partitioned into an advance chamber 612 and a retard chamber 611 by a vane 621 formed on the outer peripheral portion of the rotor 62. Has been.

  The hydraulic fluid stored in the oil pan 81 is supplied from the hydraulic pump 82 to the hydraulic pressure (particularly hydraulic) circuit of the variable valve timing mechanism 6. The hydraulic pump 82 is driven by power from the internal combustion engine. An OCV (Oil Control Valve) 9 that is a switching control valve is provided between the hydraulic pump 82 and the variable valve timing mechanism 6. By operating the flow rate and direction of the hydraulic fluid via the OCV 9, the hydraulic fluid pumped from the oil pan 81 can be selectively supplied to the advance chamber 612 or the retard chamber 611. Then, the housing 61 rotates relative to the rotor 62, and the opening / closing timing of the intake valve can be advanced or retarded.

  The OCV 9 is a so-called electromagnetic four-way spool valve. As shown in FIG. 4, the OCV 9 has a supply port 91 connected to the discharge port of the hydraulic pump 82, an A port 92 connected to the advance chamber 612 of the housing 61, and a B port connected to the retard chamber 611 of the housing 61. 93 and drain ports 94 and 95 connected to the oil pan 81. The spool of the OCV 9 switches the internal particle path by an advancing and retreating operation, and connects the A port 92 and the B port 93 to one of the supply port 91 and the drain ports 94 and 95, respectively. Further, when the spool 96 is in the neutral position, the internal fluid path is interrupted, and the A port 92 and the B port 93 are not communicated with the supply port 91 and the drain ports 94 and 95. FIG. 4 shows a state where the spool 96 is in the neutral position.

  The spool 96 is driven by a solenoid 97. That is, the advance / retreat distance of the spool 96 changes according to the duty ratio of the pulse current (or voltage) input to the solenoid 97 as the control signal m.

  When the duty ratio of the control signal n is relatively large, the hydraulic fluid pressure discharged from the hydraulic pump 82 is supplied to the advance chamber 612 through the A port 92, while already stored in the retard chamber 611. The hydraulic fluid flows down toward the oil pan 81 through the B port 93, and the vane 621 and the rotor 62 are rotated so that the volume of the advance chamber 612 is enlarged and the volume of the retard chamber 611 is reduced. As a result, the rotational phase of the intake camshaft 63, in other words, the displacement angle of the intake camshaft 63 with respect to the crankshaft is advanced, and the valve timing of the intake valve 35 is advanced.

  On the other hand, when the duty ratio of the control signal n is relatively small, the hydraulic fluid pressure discharged from the hydraulic pump 82 is supplied to the retard chamber 611 through the B port 93 while being already stored in the advance chamber 612. The working fluid that has flown down flows toward the oil pan 81 through the A port 92, and the vane 621 and the rotor 62 rotate so that the volume of the retard chamber 611 is expanded and the volume of the advance chamber 612 is decreased. . As a result, the displacement angle of the intake camshaft 63 with respect to the crankshaft is retarded, and the valve timing of the intake valve 35 is retarded.

  Generally speaking, the valve timing of the intake valve 35 is advanced as the duty ratio of the control signal n is increased, and the valve timing of the intake valve 35 is delayed as the duty ratio is decreased.

  The ECU 0 that is a control device that controls the operation of the internal combustion engine is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, Accelerator depression signal c output from a sensor that detects the amount of depression of the accelerator pedal (so-called required load), brake depression signal d output from a sensor that detects the depression amount of the brake pedal or master cylinder pressure, and intake passage 3 (particularly, the intake air temperature signal e output from the intake air temperature sensor for detecting the intake air temperature in the surge tank 33), the cooling water temperature signal f output from the water temperature sensor for detecting the cooling water temperature of the engine, and the shift lever range. Shift range signal g output from sensor (shift position switch) for learning, intake camshaft or The cam angle signal (G signal) h output from the cam angle sensor at a plurality of cam angles of the exhaust camshaft, the acceleration signal i output from the acceleration sensor, and the lubrication output from the oil temperature sensor for detecting the lubricating oil temperature An oil temperature signal j or the like is input.

  From the output interface, the ignition signal k is output to the igniter of the spark plug 12, the fuel injection signal 1 is output to the injector 11, the opening operation signal m is output to the throttle valve 32, the control signal n is output to the OCV 9, and the like. .

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 obtains various information a, b, c, d, e, f, g, h, i, j necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and uses the cylinder 1 Estimate the amount of intake air to be filled. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. A known method can be adopted as the operation parameter determination method itself. The ECU 0 applies various control signals k, l, m, and n corresponding to the operation parameters via the output interface.

In addition, the ECU 0 executes the idle stop control program built in the memory so that the idle stop condition is satisfied, specifically, the shift position indicated by the shift range signal g is the travel range (AT In the case of a car), the depression amount of the brake pedal indicated by the brake depression amount signal d is equal to or greater than the predetermined depression amount, the upward gradient indicated by the acceleration signal i is equal to or less than the upward gradient determination threshold, and the vehicle battery voltage is equal to or higher than the predetermined voltage. Yes, the cooling water temperature of the internal combustion engine indicated by the cooling water temperature signal f is _{equal to} or higher than the predetermined water temperature T _W0 , the oil temperature of the lubricating oil indicated by the oil temperature signal k is _{equal to} or higher than the predetermined oil temperature T _O0 , and the intake air temperature signal e indicates temperature is the predetermined intake air temperature T _A0 above, it is determined whether conditions are satisfied across the board etc., the operation of the internal combustion engine when the idle stop condition is satisfied Performs control to stop.

  The ECU 0 inputs a control signal p to a starter motor (cell motor, not shown) when the internal combustion engine is started (a cold start or a return from an idling stop). Cranking is performed by rotating the engine by engaging the pinion gear of the motor with the ring gear on the outer periphery of the drive plate. Cranking ends from the first explosion to the consecutive explosion, and ends when the engine speed exceeds a judgment value determined according to the cooling water temperature or the like (assuming that the explosion has been completed).

In addition, the ECU 0 stops the operation of the internal combustion engine by the control of the idle stop control program described above, and then the CPU executes the intake valve opening / closing timing control program built in the memory, so that the engine temperature exceeds a predetermined temperature, In addition, when the intake air temperature exceeds the predetermined intake air temperature, the valve opening timing of the intake valve 35 is retarded to perform adiabatic expansion of the air in the cylinder. Here, in the present embodiment, the cooling water temperature of the internal combustion engine indicated by the water temperature signal j exceeds the predetermined water temperature T _W0 , or was in a high load operation state immediately before performing the idle stop, that is, the accelerator pedal stroke signal c indicates If the accelerator pedal depression amount exceeds the predetermined depression amount, it is determined that “the engine temperature exceeds the predetermined temperature”.

  Hereinafter, the procedure of processing executed by the ECU 0 by the intake valve opening / closing timing control program of the present embodiment will be described with reference to FIG.

First, idling stop is performed, in other words, fuel cut is performed in response to the establishment of the idling stop condition, and the internal combustion engine is rotating due to inertia until it stops (step S1). The temperature is higher than the predetermined temperature, in other words, the cooling water temperature of the internal combustion engine is higher than the predetermined water temperature T _W0 or the accelerator pedal depression amount just before the idling stop is higher than the predetermined depression amount (step S2). If the intake air temperature exceeds the predetermined intake air temperature _TA0 (step S3), the opening timing of the intake valve 35 is retarded by a predetermined crank angle, in this embodiment, about 60 ° CA after exhaust top dead center (step S4). ). On the other hand, when the engine temperature does not exceed the predetermined temperature or when the intake air temperature does not exceed the predetermined intake air temperature T _A0 , the intake valve 35 is opened at normal timing (step S5).

That is, according to the present invention, when the engine temperature exceeds the predetermined temperature and the intake air temperature exceeds the predetermined intake air temperature T _A0 , the opening timing of the intake valve 35 is set to about 60 ° after the exhaust top dead center. By retarding to CA, the air in the cylinder adiabatically expands from the exhaust top dead center until the intake valve 35 is opened, thereby cooling the air in the cylinder and the cylinder block constituting the inner wall of the cylinder. . Accordingly, even immediately after returning from the idle stop, it is possible to suppress the occurrence of knocking due to the high-temperature air-fuel mixture being compressed and self-ignited.

On the other hand, even if the engine temperature exceeds the predetermined temperature, if the intake air temperature does not exceed the predetermined intake air temperature _TA0 , the opening timing of the intake valve 35 is not retarded. Therefore, the adiabatic expansion of the air in the cylinder and the cooling of the cylinder block do not occur, and deterioration of the startability due to excessive cooling of the inside of the cylinder and the cylinder block can be suppressed.

  The present invention is not limited to the embodiment described above.

  For example, the vehicle control device that performs fuel cut during deceleration without performing idling stop may delay the opening timing of the intake valve when the engine temperature exceeds a predetermined value during fuel cut. Also in this case, it is possible to cool the cylinder and the cylinder block during the fuel cut and suppress the occurrence of knocking when returning from the fuel cut.

  In the above-described embodiment, when the intake air temperature does not exceed the predetermined intake air temperature, the valve opening timing of the intake valve is not retarded. Even when the retarding mode is adopted, it is possible to suppress the occurrence of knocking immediately after returning from the fuel cut state.

  In addition, various changes may be made without departing from the spirit of the present invention.

0 ... ECU (control device)
6 ... VVT (Variable valve timing mechanism)
c ... accelerator pedal stroke signal e ... intake air temperature signal f ... cooling water temperature signal

Claims (3)

Controlling an internal combustion engine mounted on a vehicle and capable of changing the opening and closing timing of the intake valve,
A control apparatus for an internal combustion engine, characterized in that when fuel cut is performed when the engine temperature exceeds a predetermined value, control is performed to retard the opening timing of the intake valve. A control device that performs idling stop that stops idling of an internal combustion engine that is mounted on a vehicle and that can change the opening and closing timing of an intake valve,
A control apparatus for an internal combustion engine, wherein control is performed to retard the opening timing of an intake valve when fuel injection is stopped to perform idle stop and the internal combustion engine is inertially rotating. 3. The control device for an internal combustion engine according to claim 1, wherein when the intake air temperature is lower than a predetermined temperature, control for retarding the valve opening timing of the intake valve is not performed.

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