JP2015040543A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the extension of a delay period from the establishment of a fuel cut condition up to a start of a fuel cut.SOLUTION: In a control device of an internal combustion engine which comprises a blow-by gas recirculation device having a PCV (positive crankcase ventilation) passage which communicates an internal chamber where a blow-by gas is accumulated with a region on the downstream side of a throttle valve in an intake passage, and a PCV valve which opens and closed the PCV passage, the PCV valve is closed and the PCV passage is blocked during a delay period from establishment of a fuel cut condition until a start of a fuel cut of temporarily stopping fuel supply to a cylinder.

Description

  The present invention relates to a control device that controls operation of an internal combustion engine.

  The crank chamber of the internal combustion engine is isolated from the combustion chamber by the bore inner wall of the cylinder and the piston. However, this isolation is not perfect, and unburned gas leaks in the compression stroke of the internal combustion engine, and combustion gas leaks into the crank chamber through the gap between the bore inner wall and the piston in the expansion stroke. The leaked blow-by gas causes deterioration of the lubricating oil stored in the crank chamber and corrosion of the internal combustion engine body.

  Therefore, conventionally, it has been customary to mount a device for ventilating blow-by gas accumulated in the crank chamber. A general blow-by gas recirculation device (see, for example, Patent Document 1 below) includes a PCV passage that communicates a crank chamber with a surge tank on an intake passage, and a PCV valve that opens and closes the PCV passage. The blow-by gas in the crank chamber is sent toward the intake passage via the PCV passage, is filled into the cylinder together with the intake air, and is finally recombusted in the combustion chamber. The PCV valve prevents backflow of blow-by gas and intake air from the intake passage toward the crank chamber.

  In an internal combustion engine mounted on a vehicle or the like, it is known to perform a fuel cut that temporarily stops fuel injection in accordance with the operation state. Normally, when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed, the fuel cut is started assuming that the fuel cut condition is satisfied. Then, when any fuel cut end condition is satisfied, such as when the accelerator pedal depression amount exceeds the threshold value, or the engine speed decreases to the fuel cut return speed, the fuel cut ends and the fuel injection resumes. .

  When the fuel supply is suddenly cut off at a stage where the output torque of the internal combustion engine is relatively large, a torque shock occurs in which the engine speed and the vehicle speed drop stepwise, causing the passengers including the driver to feel the shock. In order to reduce this torque shock, even if the fuel cut condition is satisfied, the fuel injection is not stopped immediately, and delay control is performed to stop the fuel injection only after a certain delay time has elapsed (for example, (See Patent Document 2 below).

Japanese Utility Model Publication No. 60-040812 Japanese Patent Laid-Open No. 10-030477

  However, if the PCV valve is open during the delay period from when the fuel cut condition is established to when fuel cut is actually started, gas is sucked from the crank chamber via the PCV passage due to negative pressure generated downstream of the throttle valve. It is put out and it will be in the state supplied to a surge tank one after another. As a result, the start of fuel cut is delayed in combination with the fact that the amount of intake air charged into the cylinder is not sufficiently reduced and the engine torque does not drop moderately. If the start of the fuel cut is delayed, the fuel is wasted correspondingly and the effective fuel consumption is deteriorated.

  The present invention has been made by paying attention to the above-mentioned problem for the first time, and an object thereof is to suppress the extension of the delay period from the establishment of the fuel cut condition to the start of the fuel cut.

  In the present invention, there is provided an internal combustion engine having a PCV passage communicating with an inner chamber in which blowby gas accumulates and a portion downstream of a throttle valve in an intake passage, and a blowby gas recirculation device having a valve for opening and closing the PCV passage. An internal combustion engine control comprising: closing a valve in a delay period after a predetermined fuel cut condition is satisfied and before starting a fuel cut for temporarily stopping fuel supply to a cylinder Configured the device. Here, the inner chamber is a concept including a crank chamber in which blow-by gas is generated, a cam chamber communicating with the crank chamber, and the like.

  According to the present invention, extension of the delay period from the establishment of the fuel cut condition to the start of the fuel cut can be suppressed.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment implements.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type 4-stroke 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 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.

  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.

  The blow-by gas recirculation device 6 is for sending blow-by gas generated in the inner chambers 7 and 8 of the internal combustion engine to the intake passage 3, and includes the PCV passage 61, the PCV valve 62, and the blow-by passage 63 as elements. .

  One end of the PCV passage 61 is connected to the crank chamber 7, and the other end is connected to a predetermined portion of the intake passage 3 downstream of the throttle valve 33, particularly to the surge tank 33, and the crank chamber 7 communicates with the intake passage 3. Let me. Blow-by gas in the crank chamber 7 is discharged to the intake passage 3 via the PCV passage 61.

  The PCV valve 62 increases or decreases the flow rate of blow-by gas flowing through the PCV passage 61. In the present embodiment, the PCV valve 62 is installed at a location where the PCV passage 61 is connected to the crank chamber 7. In the present embodiment, the PCV valve 62 is an electromagnetic PCV valve that can be opened and closed by inputting a control signal l, or its opening degree can be arbitrarily controlled.

  An oil separator (not shown) is interposed between the crank chamber 7 and the PCV valve 62. The oil separator has a labyrinth structure and performs a gas-liquid separation action for separating the lubricating oil contained in the flowing gas from the gas, and prevents the lubricating oil from being lost from the crank chamber 7.

  One end of the blow-by passage 63 is connected to the cam chamber 8 in the cylinder head cover of the internal combustion engine, and the other end is connected to a predetermined portion of the intake passage 3 upstream of the throttle valve 32, and the cam chamber 8 is connected to the intake passage 3. Communicate with. An oil separator is also provided at a location where the blow-by passage 63 is connected to the cam chamber 8.

  When the PCV valve 62 is open, blow-by gas in the cam chamber 8 and the crank chamber 7 is sent out to the intake passage 3 via the PCV valve 62 and the PCV passage 61. At the same time, fresh air flows into the cam chamber 8 and the crank chamber 7 from the intake passage 3 via the blow-by passage 63, and the cam chamber 8 and the crank chamber 7 are ventilated. The blow-by gas returned to the surge tank 33 in the intake passage 3 is filled in the cylinder 1 and recombusted.

  The opening degree of the PCV valve 62 is basically increased as the differential pressure between the crank chamber 7 and the surge tank 33 increases. However, in the region where the intake pressure in the surge tank 33 is significantly reduced (the intake negative pressure is increased), the opening degree is conversely reduced as the differential pressure between the crank chamber 7 and the surge tank 33 is increased. Take characteristics. This is intended to stabilize the idling rotation by securing the amount of fresh air charged in the cylinder 1 during idling of the internal combustion engine. In the region where the pressure in the surge tank 33 is close to or higher than the atmospheric pressure (the intake pressure is positive), the PCV valve 62 is fully closed and the PCV passage 61 is shut off, and the blow-by gas or intake crank chamber 7 is closed. Prevent backflow toward

  The ECU 0 serving as a control device for 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 b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. A sensor for knowing an accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (engine output required by the driver, that is, a required load), and a shift lever range ( Shift range signal d output from the shift position switch), intake air temperature / intake pressure signal e output from the temperature / pressure sensor for detecting the intake air temperature and intake pressure in the intake passage 3 (especially the surge tank 33), internal combustion Cooling water temperature signal f output from a water temperature sensor that detects the cooling water temperature indicating the temperature of the engine, intake camshaft A cam angle signal g output from the cam angle sensor at a plurality of cam angle of shift or the exhaust camshaft, the brake depression amount signal h or the like to be output from the sensor for detecting the amount of depression of the brake pedal is inputted.

  From the output interface, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation signal l for the PCV valve 62. Etc. are output.

  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 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. 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. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

  The ECU 0 of the present embodiment executes a fuel cut that temporarily stops fuel injection from the injector 11 (and ignition by the spark plug 12) according to the driving situation. Normally, it is assumed that the fuel cut condition is satisfied when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed.

  However, even if the combustion cut condition is satisfied, the fuel injection to the cylinder 1 is not immediately stopped. FIG. 2 shows a procedure of processing executed by the ECU 0 of the present embodiment at the time of fuel cut.

  When the fuel cut condition is satisfied (step S1), the ECU 0 maintains the operation of injecting and burning the fuel into the cylinder 1 (step S2), retards the ignition timing (step S3), and outputs the internal combustion engine. Actively reduce torque. In addition, the ECU 0 fully closes the PCV valve 62 (step S4) to shut off the PCV passage 61 and prevent gas from being supplied from the crank chamber 7 to the surge tank 33 through the PCV passage 61.

  Then, the fuel injection (and ignition) is stopped (step S6) at the timing when it is considered that the situation where the fuel injection can be stopped is ready (step S5). The situation where the fuel injection may be stopped is a situation where the output torque of the internal combustion engine decreases sufficiently and does not cause a large torque shock even if the fuel injection is stopped. The ECU 0 shuts off the fuel supply to the cylinder 1 when the engine torque has dropped below the allowable torque.

  There are several possible modes for the condition at which the branch determination in step S5 is true, that is, the condition for actually stopping the combustion injection. A typical method is to repeatedly estimate the engine torque after the fuel cut condition is established based on the current engine speed, the pressure in the surge tank 33, and the like, and when the engine torque reaches the allowable torque, the fuel injection is performed. Is to stop.

  Alternatively, the length of the delay period is determined in advance based on the engine speed at the time when the fuel cut condition is satisfied, the pressure in the surge tank 33, and the like, and the delay period has elapsed since the fuel cut condition is satisfied. The branch determination may be true, that is, the fuel cut may be started. In this case, the ECU 0 provides map data that defines the relationship between the engine speed, the pressure in the surge tank 33, the cooling water temperature, the operating condition of the air conditioner and the electric load, the state of charge of the battery, and the delay period to be set. Pre-stored in memory. When the fuel cut condition is established, the ECU 0 searches the map using the engine speed, the pressure in the surge tank 33, the coolant temperature, and the like at that time as keys to know the length of the delay period. Therefore, the elapsed time from the time when the combustion cut condition is established is counted, and when the elapsed time reaches the delay period determined from the map data, it is determined that the combustion injection can be stopped.

  After the fuel cut is started, that is, the fuel injection is stopped (step S6), one of the fuel cut end conditions is satisfied, such as the accelerator pedal depression amount exceeds the threshold value, or the engine speed is reduced to the fuel cut return speed. In step S7, the fuel cut is terminated and fuel injection (and ignition) is resumed (step S8). When recovering from a fuel cut, the fuel injection amount is increased to enrich the air-fuel ratio in order to recover the lowered engine speed, and then the air-fuel ratio is converged to a value close to the theoretical target air-fuel ratio. Implement the fuel ratio control. Further, the PCV valve 62 that has been closed is allowed to open (step S9).

  In the present embodiment, the blow-by gas recirculation provided with the PCV passage 61 that connects the inner chambers 7 and 8 in which the blow-by gas accumulates with the downstream portion of the throttle valve 32 in the intake passage 3 and the valve 62 that opens and closes the PCV passage 61. The internal combustion engine attached to the device 6 is controlled, and after the predetermined fuel cut condition is established, the valve 62 is used in a delay period before the fuel cut for temporarily stopping the fuel supply to the cylinder 1 is started. The internal combustion engine control device 0 is configured to close the engine.

  According to the present embodiment, after the fuel cut condition is established, the gas is not continuously supplied from the crank chamber 7 to the surge tank 33 via the PCV passage 62, and the intake air amount filled in the cylinder 1 is rapidly reduced. It becomes like this. Therefore, it is possible to avoid the delay period before the start of the fuel cut from being prolonged, and the waste of fuel during the delay period is reduced, which contributes to further improvement in fuel efficiency. In addition, it is possible to keep the drivability high by suppressing the torque shock accompanying the stop of fuel injection.

  The present invention is not limited to the embodiment described in detail above. For example, the operation of fully closing the PCV valve 62 when the fuel cut condition is satisfied (step S1) (step S4) is executed prior to the ignition timing retardation correction (step S3) for decreasing the engine torque. Also good.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 3 ... Intake passage 32 ... Throttle valve 33 ... Surge tank 6 ... Blow-by gas recirculation device 61 ... PCV passage 62 ... PCV valve

Claims (1)

Controls an internal combustion engine attached with a blow-by gas recirculation device having a PCV passage that communicates an inner chamber in which blow-by gas accumulates with a portion downstream of the throttle valve in the intake passage, and a valve that opens and closes the PCV passage. There,
A control apparatus for an internal combustion engine, wherein after the predetermined fuel cut condition is established, the valve is closed in a delay period before starting fuel cut for temporarily stopping fuel supply to the cylinder.

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