JP2022129779A - Internal combustion engine control device - Google Patents

Abstract

To improve start-up performance through appropriately coping with an oxygen deficiency to be a factor causing delay or failure in starting up when restarting an internal combustion engine which is stopped with any one of cylinders in a valve overlapped state.SOLUTION: In the case of starting up an internal combustion engine in a stopped state with detection of a predetermined event which causes a reduction in an oxygen amount or an oxygen concentration in an intake passage leading to a cylinder, an internal combustion engine control device at least either delays a timing to start a fuel injection after starting cranking to start up an internal combustion engine, reduces a fuel injection amount during the cranking, or expands an opening of an intake throttle valve during the cranking compared to the case of starting up the internal combustion engine without the detection of the predetermined event.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for controlling an internal combustion engine mounted on a vehicle or the like as a power source.

As is well known, when starting a stopped internal combustion engine, fuel is injected from an injector while cranking (or motoring) is performed by rotating a crankshaft, which is the output shaft of the internal combustion engine, by an electric motor. This is then combusted in the cylinder, accelerating the rotation of the crankshaft. Cranking is when the internal combustion engine goes from the first explosion to the continuous explosion, and when the rotational speed of the crankshaft, that is, the engine speed, exceeds the judgment value determined according to the temperature of the cooling water of the internal combustion engine, complete explosion. and terminate.

While the internal combustion engine is stopped, oil tight leaks may occur where fuel leaks from the injectors. The leaked fuel is sucked into the cylinder when the internal combustion engine is started later, and enriches the air-fuel ratio of the air-fuel mixture. If the air-fuel ratio becomes too rich, combustion becomes unstable or misfire occurs, and there is a concern that the engine speed will not be sufficiently accelerated, resulting in starting delay or starting failure.

Therefore, when starting the internal combustion engine, if it is determined that an oil leak has occurred, the opening of the throttle valve, which is an intake throttle valve, is increased to increase the amount of air flowing through the intake passage toward the cylinder. In other words, the amount of oxygen supplied to the cylinder is increased (see, for example, the following patent documents).

JP 2020-176554 A

When the operation of the internal combustion engine is terminated, the rotation of the crankshaft may stop in a valve overlap state in which both the intake valve and the exhaust valve of any cylinder are open. A stop in the valve overlap state is relatively likely to occur in an in-line three-cylinder internal combustion engine.

When both the intake valve and the exhaust valve of one cylinder are open while the internal combustion engine is stopped, the heat convection (chimney effect) in the exhaust passage causes unburned fuel and exhaust gas vaporized in the combustion chamber of the cylinder. Reverse flow from the same cylinder into the intake passage may occur. As a result, the oxygen concentration in the intake passage decreases. Nevertheless, if the opening of the throttle valve and the amount of fuel injection are set as usual when starting the internal combustion engine, the amount of oxygen supplied to the cylinder will be insufficient, causing unstable combustion or misfiring, resulting in engine failure. Delays or poor starting may result.

An object of the present invention is to improve startability by appropriately coping with the lack of oxygen that causes start delay or start failure when restarting an internal combustion engine in which one of the cylinders has stopped due to valve overlap. is the intended purpose.

In the present invention, when starting a stopped internal combustion engine, when a predetermined event such as a decrease in the amount of oxygen or oxygen concentration in the intake passage leading to the cylinder is detected, compared with the case where it is not, Delaying the timing of starting fuel injection after the start of cranking for starting the internal combustion engine, reducing the amount of fuel injection during cranking, and increasing the opening of the intake throttle valve during cranking. A control device for an internal combustion engine is configured to implement at least one of the above.

According to the present invention, when restarting an internal combustion engine in which one of the cylinders has stopped due to a valve overlap state, it is possible to appropriately cope with the lack of oxygen that causes start delay or start failure, thereby improving startability. can be made

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and its control device according to an embodiment of the present invention; FIG. FIG. 4 is a flow diagram showing an example of the procedure of processing executed by the control device according to the embodiment according to the program; FIG. 4 is a timing chart for explaining the contents of control performed by the control device of the embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a vehicle internal combustion engine. The internal combustion engine in this embodiment is a port-injection, four-stroke, spark-ignited engine having a plurality of cylinders 1 (eg, three cylinders, one of which is shown in FIG. 1). An injector 11 for injecting fuel toward the intake port of each cylinder 1 is provided near the intake port of each cylinder 1 . A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1, respectively. The spark plug 12 receives an induced voltage generated by the ignition coil and induces spark discharge between the center electrode and the ground electrode.

An intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1 . An air cleaner 31, an electronic throttle valve 32 which is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order on the intake passage 3 from upstream.

An exhaust passage 4 for exhausting exhaust guides the exhaust generated as a result of burning fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gas are arranged on the exhaust passage 4 .

An external EGR (Exhaust Gas Recirculation) device 2 implements external EGR in which part of exhaust gas flowing through an exhaust passage 4 is recirculated to an intake passage 3 and mixed with intake air. The EGR device 2 includes an external EGR passage 21 that communicates the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR gas flowing through the EGR passage 21 by opening and closing the EGR passage 21. The EGR valve 23 that controls the flow rate is used as an element. The inlet of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4 . The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

The internal combustion engine may be accompanied by a VVT (Variable Valve Timing) mechanism 5 capable of variably controlling at least the opening/closing timing of the intake valve of each cylinder 1 . The VVT mechanism 5 for adjusting the intake valve timing is, for example, a vane type mechanism that changes the rotational phase of the intake camshaft that drives the intake valves of each cylinder 1 with respect to the crankshaft by hydraulic pressure (lubricating oil pressure), or an electric motor. It is an electric type (motor drive VVT) that changes by As is well known, the camshaft is supplied with rotational torque from the crankshaft, which is the output shaft of the internal combustion engine, and rotates following the crankshaft. A winding transmission device (not shown) for transmitting rotational torque is interposed between the crankshaft and the camshaft. The winding transmission device consists of a crank sprocket (or pulley) provided on the crankshaft side, a cam sprocket (or pulley) provided on the camshaft side, and a timing chain (or , timing belt). The VVT mechanism 5 changes the rotation phase of the camshaft with respect to the crankshaft by rotating the camshaft relative to the cam sprocket, thereby changing the opening/closing timing of the intake valve.

An ECU (Electronic Control Unit) 0, which is a control device for an internal combustion engine according to the present embodiment, is a microcomputer system having a processor, memory, input interface, output interface, and the like. The ECU 0 may be formed by connecting a plurality of ECUs or controllers so as to be able to communicate with each other via electric communication lines such as CAN (Controller Area Network).

The input interface of the ECU 0 receives a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed. , an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as the accelerator opening (so to speak, the required engine load factor or engine torque); 3 (downstream of the throttle valve 32, especially the surge tank 33 or the intake manifold 34). Oxygen concentration signal e output from a sensor that detects oxygen concentration (linear A/F sensor, _O2 sensor, etc.), output from a water temperature sensor that detects the temperature of cooling water in the internal combustion engine (indicating the temperature of the internal combustion engine) a cooling water temperature signal f output from a cam angle sensor at a plurality of cam angles of an intake camshaft of an internal combustion engine; An atmospheric pressure signal h or the like is input.

From the output interface of the ECU 0, 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 for the EGR valve 23. It outputs a signal l, a control signal m for opening/closing timing of the intake valve to the VVT mechanism 5, and the like.

The processor of the ECU 0 interprets and executes a program stored in memory in advance, calculates operating parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various types of information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine through an input interface, learns the engine speed, and injects into the cylinder 1. Estimate the amount of air. Then, the required fuel injection amount corresponding to the intake air amount, fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing (including the number of ignitions for one combustion), required EGR rate (or EGR gas amount), intake valve timing, etc. are determined. The ECU 0 applies various control signals i, j, k, l, m corresponding to the operating parameters through the output interface.

When restarting the stopped internal combustion engine (which may be a cold start or a restart from idling stop), the ECU 0 controls the electric motor (starter motor (starter motor) or motor generator; not shown). A control signal o is input, and while performing cranking (or motoring) for rotationally driving the crankshaft by the electric motor, fuel injection and spark ignition are performed. In cranking, the internal combustion engine is considered to have exploded completely when the internal combustion engine goes from the first explosion to the continuous explosion and the engine speed exceeds the complete explosion judgment value determined according to the cooling water temperature of the internal combustion engine. finish. Normally, the lower the coolant temperature of the internal combustion engine at the start, the higher the complete explosion determination value is set.

When the operation of the internal combustion engine is terminated, the rotation of the crankshaft may stop in a valve overlap state in which both the intake valve and the exhaust valve of any cylinder 1 are open. While the internal combustion engine is stopped, if both the intake valve and the exhaust valve of one cylinder 1 are open, heat convection in the exhaust passage 4 causes unburned fuel and exhaust gas vaporized in the combustion chamber of the cylinder 1 to flow together. Reverse flow from the cylinder 1 to the intake passage 3 may occur. As a result, the oxygen concentration downstream of the throttle valve 32 in the intake passage 3 decreases. Nevertheless, if the opening of the throttle valve 32 and the fuel injection amount at the start of the internal combustion engine are set as usual, the amount of oxygen supplied to the combustion chamber of cylinder 1 will be insufficient, resulting in insufficient fuel combustion. This can lead to stabilizing or misfiring, and the engine will not accelerate sufficiently during cranking, resulting in a delayed or poor start.

Therefore, as shown in FIG. 2, when the ECU 0 of the present embodiment senses a predetermined event such that the oxygen amount or oxygen concentration in the intake passage 3 connected to the cylinder 1 decreases (step S1), Compared to the case where it is not, the timing to start injecting fuel after the start of cranking for starting the internal combustion engine is delayed (step S2), the fuel injection amount during cranking is further reduced (step S3), or , and increasing the opening of the throttle valve 32 during cranking (step S4).

In step S1, for example, the angles of the crankshaft and camshaft when the internal combustion engine is stopped are obtained by referring to the output signal b of a crank angle sensor (preferably an MRE (MagnetoResistive Effect) sensor), It is determined whether or not the rotation of the crankshaft has stopped in a valve overlap state in which both the intake valve and the exhaust valve of any cylinder 1 are open. The fact that any cylinder 1 is stopped in the valve overlap state means that the oxygen amount or oxygen concentration in the intake passage 3 connected to the cylinder 1 is reduced during the stop, that is, the condition of step S1 is satisfied. means

Alternatively, when starting cranking of the internal combustion engine, the oxygen amount or oxygen concentration in the intake passage 3 connected to the cylinder 1 is obtained by referring to the output signal e of the oxygen concentration sensor, and the oxygen amount or oxygen concentration is obtained. is lower than the threshold value, it may be determined that the condition of step S1 is established.

In addition to the above, the fact that the stop time before starting the internal combustion engine is longer than a predetermined value may be added to the condition for establishment of step S1.

When the condition of step S1 is established, as already described, the timing of performing the first fuel injection after starting cranking for starting is delayed more than usual (step S2), or the timing during cranking is delayed. The fuel injection amount is decreased from normal (step S3), or the opening of the throttle valve 32 is increased from normal (step S4). If the start of fuel injection is delayed, the air containing no fuel injected from the injector 11 is caused to flow from the intake passage 3 into the cylinder 1 and the exhaust passage 4, thereby removing the unburned air remaining when the internal combustion engine was stopped most recently. Fuel and exhaust gas can be scavenged. If the fuel injection amount is reduced, excessive enrichment of the air-fuel ratio of the air-fuel mixture charged in the cylinder 1 can be suppressed. If the opening of the throttle valve 32 is increased, the intake pressure downstream of the throttle valve 32 becomes closer to the atmospheric pressure, allowing a larger amount of oxygen to be supplied to the combustion chamber of cylinder 1, thus avoiding an over-rich air-fuel ratio. All of these contribute to stabilization of combustion during cranking. All of steps S2 to S4 may be performed, or only some of them may be performed.

The control of steps S2 to S4 ends when the engine speed rises to a predetermined value or more (step S5), and thereafter shifts to normal control (step S6).

FIG. 3 illustrates the contents of the control executed by the ECU 0 during cranking for starting the internal combustion engine and immediately after the end of cranking (completion of starting). In FIG. 3, the normal control when the condition of step S1 is not satisfied, that is, when none of the cylinders 1 is in the valve overlap state when the internal combustion engine is stopped most recently, is drawn with a dashed line, and step The solid line shows the control when the condition of S1 is satisfied, that is, when any cylinder 1 is in the valve overlap state when the internal combustion engine is stopped most recently.

Before the time _t0 when cranking is started, the throttle valve 32 is at a predetermined opener opening that is not fully closed. The opener opening is determined by a spring that elastically biases the valve body in a state in which no electric power is applied to the electric motor that drives the butterfly valve body of the electronic throttle valve 32 and no driving force is applied to the valve body from the electric motor. is the opening when the posture is maintained.

In addition, when the condition of step S1 is satisfied, the throttle valve 32 is expanded as soon as possible after the cranking start point _t0 , as indicated by the solid line in FIG. An operation is performed (step S4). The opening degree of the throttle valve 32 at this time is larger than the opener opening degree, and is larger than the opening degree when the condition of step S1 is not satisfied. The degree of opening at this time can be adjusted according to the length of the stop time (soak time) before starting the internal combustion engine and the oxygen amount or oxygen concentration in the intake passage 3 at the time of starting. For example, the longer the stop time, the greater the throttle valve opening 32, and/or the lower the oxygen concentration indicated by the oxygen concentration signal e, the greater the throttle valve opening 32.

On the other hand, if the condition of step S1 is not _satisfied , as indicated by the solid line in FIG. Shrink less than the opening.

Further, when the condition of step S1 is satisfied, the amount of fuel injected from the injector 11 is reduced more than when the condition of step S1 is not satisfied (step S3). The amount of fuel injection at this time can be increased or decreased according to the length of time the internal combustion engine is stopped before starting and the amount or concentration of oxygen in the intake passage 3 at the time of starting. For example, the longer the stop time, the smaller the fuel injection amount, and/or the lower the oxygen concentration indicated by the oxygen concentration signal e, the smaller the fuel injection amount.

Further, when the condition of step S1 is satisfied, the timing of starting fuel injection from the injector 11 is delayed to time t2, which is later _than when the condition of step S1 is not satisfied (step S2). It doesn't matter if you do. The timing t2 of the _first fuel injection after the start of cranking can also be adjusted according to the length of the stop time before starting the internal combustion engine and the oxygen amount or oxygen concentration in the intake passage 3 at the time of starting. . For example, the longer the stop time, the later the first fuel injection, and/or the lower the oxygen concentration indicated by the oxygen concentration signal e, the later the first fuel injection.

After the time t1 when the engine speed is accelerated to _a predetermined value or more (step S5), the opening degree of the throttle valve 32 and the fuel injection amount are equally controlled (step S6) regardless of whether the condition of step S1 is met. become.

In this embodiment, when starting a stopped internal combustion engine, if a predetermined event such as a decrease in the amount of oxygen or the oxygen concentration in the intake passage 3 connected to the cylinder 1 is sensed, it is compared with the case where it is not. Then, the timing to start injecting fuel after the start of cranking for starting the internal combustion engine is delayed, the fuel injection amount during cranking is further reduced, and the opening of the intake throttle valve 32 during cranking is further increased. A control device 0 for an internal combustion engine is constructed that implements at least one of enlarging.

According to this embodiment, when the internal combustion engine is restarted after any cylinder 1 stops in the valve overlap state, the amount of oxygen supplied to the cylinder 1 is insufficient, or the air-fuel ratio of the air-fuel mixture is low. It is possible to effectively avoid the problem of unstable combustion due to excessive richness. As a result, it becomes possible to start the internal combustion engine quickly and reliably.

The present invention is not limited to the embodiments detailed above. For example, if an idle speed control valve is installed as an intake throttle valve together with the throttle valve 32 in the intake passage 3 of the internal combustion engine, in step S4 of control during cranking for starting the internal combustion engine, this idle speed By increasing the opening of the control valve, the flow rate of the intake air flowing from the intake passage 3 toward the cylinder 1 is increased, and the intake pressure in the surge tank 33 or intake manifold 34 connected to the cylinder 1 is reduced to atmospheric pressure. can be brought closer to As is well known, the idle speed control valve is a flow rate control valve that opens and closes a bypass connecting the upstream side and the downstream side of the throttle valve 32 in the intake passage 3 .

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

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

0... Control unit (ECU)
1... Cylinder 3... Intake passage 32... Throttle valve (intake throttle valve)
4 Exhaust passage b Crank angle signal c Accelerator opening signal d Intake air temperature/intake pressure signal e Oxygen concentration signal f Cooling water temperature signal i Ignition signal j Fuel injection signal k Throttle valve opening operation signal

Claims (1)

When starting a stopped internal combustion engine, if a predetermined event such as a decrease in the amount of oxygen or the concentration of oxygen in the intake passage leading to the cylinder is detected, the starting of the internal combustion engine is compared with that in the other case. delaying the timing of starting fuel injection after the start of cranking, reducing the amount of fuel injection during cranking, and increasing the opening of the intake throttle valve during cranking. A controller for an internal combustion engine that implements one.

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