JPH0828311A - Control device for engine - Google Patents

Abstract

PURPOSE:To provide a control device which reduces discharge rates of HC and NOx under, a cold time of a four-cycle engine which has an intake port opened/closed by an intake valve and a fuel valve. CONSTITUTION:Combusted gas circulation valves 32a, 32b which are minutely opened in an initial period of an exhaust process under colt time are provided for circulating the combusted gas to intake parts 5a, 5b. The combusted gas circulation valve serves as an intake valve 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device, and more particularly to a four-cycle engine having a fuel injection valve in an intake port opened and closed by an intake valve, particularly for improving emission characteristics in a cold state. The present invention relates to an engine control device.

[0002]

In a conventional engine for a vehicle, in view of exhaust gas purification, by refluxing a part of exhaust gas to the intake system or combustion chamber, NO _X rows to reduce the content of the exhaust gas It is being appreciated.

In this exhaust gas recirculation (hereinafter referred to as "EGR"), an exhaust passage and an intake passage are connected by a pipe provided with a flow rate control valve (EGR valve) in the middle, and exhaust gas is exhausted through this pipe. External EGR that returns a part to the intake system
Method and internal E that allows some of the burnt gas to remain in the combustion chamber
It is roughly divided into the GR system.

By the way, in the case of the internal EGR system, since a part of the burnt gas remains in the combustion chamber, the residual gas having a relatively high temperature heats the new air-fuel mixture, so that the vaporization of the fuel can be promoted. it can. And this internal EGR
Can be achieved by lengthening the overlap period between the intake stroke and the exhaust stroke.
Japanese Laid-Open Patent Publication No. 64 discloses an engine in which the internal EGR amount according to the operating state of the engine is obtained by varying the overlap period between the intake stroke and the exhaust stroke.

On the other hand, in a conventional four-cycle engine having a fuel injection valve in the intake port, liquid fuel adheres to the wall surface of the intake port, especially during cold weather.
The HC content in the exhaust gas is large, and its reduction has been desired.

By the way, during the overlap period between the exhaust stroke and the subsequent intake stroke, a part of the burned gas having a relatively high temperature is recirculated to the intake port at supersonic speed, and this burned gas is Since it acts to vaporize the liquid fuel adhering to the wall surface of the intake port during cold, by increasing the overlap period, the H during cold is increased.
It is known that the amount of C emission can be reduced.

[0007]

However, if the overlap period is lengthened, there is a problem that the stability of combustion is impaired depending on the operating condition. Further, the burned gas is recirculated to the intake port during the overlap period. However, since it is performed at the end of the exhaust stroke when the cylinder pressure drops, the supersonic flow of burnt gas occurs only at the very beginning of the overlap period. The effect of reducing HC emission was slight.

In view of the above-mentioned circumstances, it is an object of the present invention to provide an engine control device that effectively utilizes the supersonic flow of recirculated burned gas to reduce the HC emission amount during cold conditions. To do.

[0009]

An engine control device according to the present invention is a control device for a four-cycle engine having a fuel injection valve in an intake port opened and closed by an intake valve. As shown in b), a burned gas recirculation valve that opens a small amount of fuel according to the operating state for a predetermined period from the end of the combustion stroke to the beginning of the intake stroke to recirculate burned gas to the intake port is provided. It is characterized by

The burnt gas recirculation valve is controlled so as to open when the engine is cold, and the intake valve can also be used as the burnt gas recirculation valve.

In one aspect of the present invention, the intake valve is composed of first and second intake valves provided in a common intake port, and both the first and second intake valves are burned. The fuel injection valve is also used as a gas recirculation valve, and the fuel injection valve is provided at the center of the common intake port. Then, when the load is low, it is preferable that the opening operation of the second intake valve in the intake stroke is stopped and the second intake port is closed.

In another aspect of the present invention, the intake valve is provided in a common intake port and comprises first and second intake valves, and only the first intake valve is also used as the burned gas recirculation valve. In addition, the fuel injection valve is provided offset to the first intake valve side. Also in this case, it is preferable that the second intake valve is closed during the intake stroke to close the second intake port when the load is low.

In still another aspect of the present invention, the intake valve comprises first and second intake valves respectively provided in first and second intake ports formed independently of each other, Only the first intake valve is used also as the burnt gas recirculation valve, and the fuel injection valve is provided in the first intake port. Also in this case, when the load is low, the opening operation of the second intake valve in the intake stroke is stopped, or the swirl control valve provided in the second intake port is closed to close the second intake port. Is preferably configured to be closed.

In order to drive the first and second intake valves, one camshaft is provided with a first burnt gas recirculation cam, an intake cam and a second burnt gas recirculation cam. A first rocker arm that engages with the first burned gas recirculation cam and a first intake valve that engage with the first burned gas recirculation cam are engaged with a rocker shaft that is arranged in parallel in this order and that is arranged parallel to the cam shaft. A second rocker arm, a third rocker arm that engages with the intake cam, a fourth rocker arm that engages with the second intake valve, and a second burned gas recirculation cam. A fifth rocker arm to be engaged is arranged adjacent to each other so as to be swingable, and two rocker arms adjacent to each other are selectively switched to an interlocking state or a non-interlocking state, respectively. Third and fourth switching means are provided.

The fuel injection by the fuel injection valve is performed in synchronization with the opening timing of the burnt gas recirculation valve (intake valve). The end point of this fuel injection is generally set in the first half of the open period of the burned gas recirculation valve, but when the fuel injection period is longer than the open period of the burned gas recirculation valve, it is injected from the fuel injection valve. The fuel injection is started before the opening start time of the burnt gas recirculation valve for the time T required for the fuel to reach the opening of the intake port into the combustion chamber.

Further, intake port throttle means is provided at an intake port upstream or downstream of the fuel injection valve, and when the fuel injection period by the fuel injection valve is longer than the open period of the burnt gas recirculation valve, the intake air is taken. The port throttle means is activated.

Further, the fuel injection by the fuel injection valve is
In addition to synchronizing with the opening timing of the burnt gas recirculation valve, it may be performed during the overlap period between the opening period of the exhaust valve and the opening period of the intake valve.

Further, the fuel injection direction of the fuel injection valve may be directed to the upper wall portion of the intake port. In that case, the fuel injection period of the fuel injection valve is set before the opening period of the burnt gas recirculation valve.

According to still another aspect of the engine control apparatus of the present invention, the first fuel injection for injecting fuel toward the upper wall portion of the intake port in synchronization with the opening timing of the burnt gas recirculation valve. Second fuel injection valve that injects fuel toward the opening of the intake port to the combustion chamber in synchronization with the intake stroke in the operating state in which the valve opening operation of the valve and the burnt gas recirculation valve is stopped. It has and.

In that case, when the first and second intake valves are provided in a common intake port, the first intake valve is also used as the burnt gas recirculation valve, and the first fuel injection is performed. A valve is provided offset to the common intake port on the side of the first intake valve, and the second fuel injection valve is provided in the center of the common intake port.

Further, in the case where the first intake port opened and closed by the first intake valve and the second intake port opened and closed by the second intake valve are provided independently of each other, the above first The intake valve is also used as the burnt gas recirculation valve, the first fuel injection valve is provided in the first intake port, and the second fuel injection valve is provided in the second intake port.

According to still another aspect of the engine control apparatus of the present invention, it is provided with means for swirling the burnt gas recirculated to the intake port in the intake port by opening the burnt gas recirculation valve. ing.

This means for swirling the burned gas can be obtained only by inclining and bending the intake port through which the burned gas is recirculated.
It can also be obtained by providing a deflector plate at the umbrella portion of the intake valve that also serves as the intake port or the burnt gas recirculation valve.

When the engine is a multi-cylinder engine, means for detecting the combustion state of each cylinder is provided, and the air-fuel ratio of the cylinder whose combustion speed is detected to be slow is corrected by the detection means to the rich side. Alternatively, it is preferable to advance the ignition timing of the cylinder.

Further, a shutter valve is provided in the exhaust passage of the engine, and the shutter valve is controlled to be closed during cold high load.

A means for reducing torque fluctuation that may occur at the time of switching from the operating state in which the burnt gas recirculation valve is opened to the operating state in which the open operation of the burnt gas recirculation valve is stopped is provided. Is also preferable.

The torque fluctuation reducing means comprises, for example, means for gradually controlling the opening of the shutter valve provided in the exhaust passage of the engine. The torque fluctuation reducing means also comprises means for temporarily correcting the air-fuel ratio to the lean side and then gradually returning it to the proper air-fuel ratio, or means for delaying the ignition timing once and then gradually returning it to the proper ignition timing.

Further, the torque fluctuation reducing means may be a means for gradually delaying the opening timing of the burnt gas recirculation valve.

Further, when the engine is provided with the external EGR means for recirculating the exhaust gas from the exhaust passage to the intake passage, the torque fluctuation reducing means is provided with a predetermined amount of the external EGR means.
After introducing the R amount, it comprises means for gradually decreasing the external EGR amount.

When temporary injection is performed by the fuel injection valve during acceleration of the engine, this temporary injection is performed at the beginning of the intake stroke. Further, at the time of deceleration, the ignition timing is retarded in response to the enrichment of the air-fuel ratio due to the decrease of the intake air amount.

It is preferable that the end point of the fuel injection synchronized with the start timing of the burnt gas recirculation valve is almost coincident with the closing time of the burnt gas recirculation valve.

When the fuel injection valve is provided with air assist means for ejecting air together with fuel from the fuel injection valve, the air assist means recirculates the air while the burnt gas recirculation valve is open. Air having a pressure equal to or higher than the pressure of the fuel gas is preferably ejected from the fuel injection valve.

In the present invention, the burned gas recirculation valve dedicated to the engine may be provided separately from the intake valve. In that case, the dedicated burned gas recirculation valve is provided in the burned gas recirculation port branched from the intake port, and the fuel injected from the fuel injection valve crosses the intake port to the burned gas recirculation port. In the operating state in which the fuel injection valve is directed to the burned gas recirculation port so as to face the intake port, and the burned gas recirculation valve is opened, the fuel injection valve from the fuel injection valve In the operating state in which the fuel injection is performed in synchronization with the opening timing of the burned gas recirculation valve and the opening operation of the burned gas recirculation valve is stopped, the fuel injection from the fuel injection valve is sucked. I try to synchronize with the process. Further, it is preferable that the intake valve is formed to have a larger diameter than the burnt gas recirculation valve.

[0034]

According to the present invention, a small amount of valve is opened according to the operating condition for a predetermined period between the end of the combustion stroke and the beginning of the intake stroke, and the burned gas is returned to the intake port. Since the fuel gas recirculation valve is provided, FIG.
As shown in Fig. 5, a part of the high temperature burnt gas recirculates (blows back) to the intake port at supersonic speed and collides with the fuel spray injected from the fuel injection valve, which promotes the vaporization of the fuel. , by the internal EGR effect, NO _X emissions can be reduced.

In particular, when the burnt gas is recirculated during the cold state, the coarse droplets injected from the fuel injection valve during the cold state are broken and collapsed to promote vaporization, so that they flow into the combustion chamber. The amount of fuel adhering to the wall surface is reduced, and the amount of HC emission is significantly reduced. Further, when the intake valve is composed of the first and second intake valves, the valve arrangement with respect to the combustion chamber of the engine can be achieved by using only the first intake valve or both intake valves as the burnt gas recirculation valve. There is an advantage that the present invention can be carried out only by changing the valve drive mechanism without changing it. Then, when the load is low, the swirl is generated in the combustion chamber by stopping the valve opening operation of the second intake valve in the intake stroke, and it is possible to avoid the possibility of combustibility deterioration due to the circulation of burnt gas. it can.

In order to drive the first and second intake valves, one camshaft is provided with a first burnt gas recirculation cam, an intake cam and a second burnt gas recirculation cam. Are arranged side by side in this order, and a rocker shaft arranged parallel to the cam shaft is engaged with a first rocker arm that engages with the first burnt gas recirculation cam and the first intake valve. A second rocker arm, a third rocker arm that engages the intake cam, a fourth rocker arm that engages the second intake valve, and a second burned gas recirculation A fifth rocker arm that engages with the cam is arranged adjacent to each other so as to be swingable, and two rocker arms that are adjacent to each other are selectively switched to an interlocking state or a non-interlocking state, respectively. , Third and fourth
By providing the switching means, the first to the fourth switching means are selected in the interlocked state or the non-interlocked state, so that the various first and second various types adapted to the structure of the intake port and the arrangement of the fuel injection valve are selected. It becomes possible to select the operation mode of the intake valve.

Further, in the present invention, the fuel injection by the fuel injection valve is performed in synchronism with the opening timing of the burnt gas recirculation valve (intake valve). By setting the injection end time point at which drops and fuel dripping are likely to occur in the first half of the burnt gas recirculation period in which the momentum of recirculation is large, it is possible to effectively cause the high temperature blowback gas to collide with the fuel spray.

Further, intake port throttle means is provided at an intake port upstream or downstream of the fuel injection valve, and when the fuel injection period by the fuel injection valve is longer than the open period of the burnt gas recirculation valve, the intake air is taken. Since the port throttle means is operated, the recirculation time is lengthened and the vaporization of the fuel is promoted.

In addition to performing the fuel injection by the fuel injection valve a plurality of times in synchronization with the valve opening timing of the burnt gas recirculation valve, the valve opening period of the exhaust valve and the intake valve By injecting the fuel during the overlap period with the valve opening period, the recirculation of the burnt gas during the overlap period can also be used for the vaporization of the fuel.

Further, since the burnt gas that is recirculated is biased above the intake port, the vaporization is promoted by directing the fuel injection direction of the fuel injection valve to the upper wall portion of the intake port. In this case, by setting the fuel injection period of the fuel injection valve before the opening period of the burned gas recirculation valve, the recirculated burned gas can be brought into contact with all of the injected fuel, further promoting vaporization. .

Further, when the fuel injection direction of the fuel injection valve is directed to the upper wall portion of the intake port, the fuel collides with the recirculated burned gas and vaporizes during cold time when the burned gas recirculation valve is opened. However, in the operating state in which the valve opening operation of the burnt gas recirculation valve is stopped, such as during warm time, the fuel injection direction of the fuel injection valve is directed toward the upper wall portion of the intake port. Is not very desirable. Therefore, the first fuel injection valve that injects fuel toward the upper wall portion of the intake port in synchronization with the opening timing of the burnt gas recirculation valve and the burned gas recirculation valve are not opened. By providing a second fuel injection valve that injects fuel toward the opening of the intake port to the combustion chamber in synchronization with the intake stroke in the operating state, it is possible to suppress deterioration of emission and fuel efficiency.

Further, by providing means for swirling the burnt gas which is recirculated to the intake port by opening the burnt gas recirculation valve in the intake port, the fuel spray and the fuel adhering to the wall surface are vaporized. Can be promoted.

In the case where the engine is a multi-cylinder engine, the burned gas recirculation amount also varies due to the structural variation of each cylinder, and especially when the load is low, the combustion state is poor and the intake port Since the pressure difference between the inside and the inside of the cylinder is large, the combustion state of each cylinder is different due to the variation in the recirculation amount, and the engine rotation fluctuation is likely to occur. Therefore, a means for detecting the combustion state of each cylinder is provided, and the air-fuel ratio of the cylinder whose combustion speed is detected to be slow is corrected by the detection means to the rich side, or the ignition timing of the cylinder is advanced. As a result, it is possible to suppress the rotational fluctuation of the engine.

Further, even when the burnt gas is recirculated, at the time of cold high load, the throttle valve is largely opened and the negative pressure in the intake port is reduced, so that the recirculation amount is reduced. By providing a shutter valve in the exhaust passage of the engine and controlling the closing of the shutter valve during cold high load, the exhaust pressure is increased and a sufficient recirculation amount can be obtained. Further, since the EGR can be performed at the time of high load, the NO _X emission amount is reduced.

Furthermore, when the operating state in which the burnt gas recirculation valve is opened is switched to the operating state in which the open operation of the burnt gas recirculation valve is stopped, the internal EGR is rapidly lost, so that the combustion state is Torque shock occurs due to abrupt changes, but at the time of the above switching, the combustion state is gradually changed by gradually controlling the opening of the shutter valve provided in the exhaust passage of the engine to suppress the occurrence of torque shock. be able to.

Further, at the time of switching, the air-fuel ratio is once corrected to the lean side and then gradually returned to the proper air-fuel ratio, or the ignition timing is once retarded and then gradually returned to the proper ignition timing. Therefore, it is possible to prevent the combustion state from being abrupt, and it is possible to suppress the occurrence of torque shock.

Further, at the time of the above switching, the burning operation of the burnt gas recirculation valve is not immediately stopped, but the burning operation is stopped by gradually delaying the valve opening timing and then stopping the burning gas recirculation valve. Since the state changes gradually, the occurrence of torque shock can be suppressed.

Further, when the engine is provided with the external EGR means for recirculating the exhaust gas from the exhaust passage to the intake passage, a predetermined amount of the external EGR amount is once introduced at the time of the switching, and then the external EGR amount is gradually increased. Since the EGR amount can be gradually reduced by decreasing the amount to 1, the occurrence of torque shock can be suppressed.

By the way, since the high-temperature burnt gas that has recirculated by blowback passes through the intake port toward the combustion chamber together with the intake air at the beginning of the intake stroke, when temporary injection is performed by the fuel injection valve during acceleration of the engine. , By performing this temporary injection at the beginning of the intake stroke,
The vaporization of the spray is promoted and the amount of fuel adhering to the wall surface of the intake port is reduced. Therefore, the delay in fuel transportation is reduced and the responsiveness is improved. Further, since it is not necessary to increase the amount of fuel for the purpose of adhering to the wall surface, fuel consumption is improved and the amount of HC emission is suppressed.

Further, at the time of deceleration from the open state to the closed state of the throttle valve, the air-fuel ratio becomes rich as the intake air amount decreases until fuel cut is performed,
Although the HC discharge amount increases, the exhaust gas temperature rises by retarding the ignition timing, so that the increase in the HC discharge amount can also be suppressed.

Further, if the nozzle of the fuel injection valve is directly exposed to the burnt gas that has recirculated, the nozzle may be clogged. Therefore, the nozzle of the fuel injection valve is directly exposed to the recirculated burned gas by making the end time of fuel injection synchronized with the start timing of the burned gas recirculation valve almost coincide with the closing time of the above burned gas recirculation valve. Can be avoided.

Further, when the fuel injection valve is provided with air assist means for ejecting air together with the fuel from the fuel injection valve, during the opening of the burnt gas recirculation valve,
By injecting air having a pressure equal to or higher than the pressure of the recirculated burned gas by the air assist means from the fuel injection valve, direct exposure of the nozzle of the fuel injection valve to the recirculated burned gas can be avoided.

Further, if the engine is provided with a dedicated burned gas recirculation valve separately from the intake valve, the valve operating mechanism is simplified and the cam drive loss when the intake valve is also used as the burned gas recirculation valve. Can be reduced. In that case, the dedicated burned gas recirculation valve is provided in the burned gas recirculation port branched from the intake port, and the fuel injected from the fuel injection valve crosses the intake port to the burned gas recirculation port. In the operating state in which the fuel injection valve is directed to the burned gas recirculation port so as to face the intake port, and the burned gas recirculation valve is opened, the fuel injection valve from the fuel injection valve In the operating state in which the fuel injection is performed in synchronization with the opening timing of the burned gas recirculation valve and the opening operation of the burned gas recirculation valve is stopped, the fuel injection from the fuel injection valve is sucked. By performing the process in synchronization with the stroke, the break-up length of the fuel spray can be secured, and the amount of fuel adhering to the wall surface in the intake port can be reduced. Further, the burned gas recirculation valve may have the same diameter as the intake valve, but by forming the intake valve to have a larger diameter than the burned gas recirculation valve, the fuel blown back into the intake air at the time of reburning the burned gas. Flows into the combustion chamber from the position of the large-diameter intake valve and diffuses in a wide range, and when the recirculation is stopped, the fuel spray is bent into the intake air by the fuel injection synchronized with the intake stroke and burns from the position of the large-diameter intake valve. Since it flows into the room and diffuses over a wide range, there is an advantage that mixing with intake air is promoted and the combustibility is improved.

[0054]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIG. 2, an engine E according to the present invention includes a piston 2 slidably housed in a cylinder bore 1a of a cylinder block 1 and a cylinder head 3 fixed to the upper end of the cylinder block 1. And a combustion chamber 4 is formed by the cylinder block 1, the piston 2, and the cylinder head 3.

In the cylinder head 3, as shown in FIG. 3 (a), first and second intake ports 5a, 5b and first and second exhaust ports 6a, which open to the combustion chamber 4, are formed.
6b is provided, and the intake ports 5a and 5b are also provided.
First and second intake valves 7a, 7b for opening and closing the
And the first to open and close the exhaust ports 6a and 6b, respectively.
And the second exhaust valves 8a and 8b are mounted.

The intake ports 5a and 5b join together on the immediately upstream side to form a common intake port 9, and the fuel injection valve 1 for injecting fuel into the intake ports 5a and 5b.
0 is attached to the center of the common intake port 9, and the fuel injection valve 10 is provided toward the partition wall 9a between the intake ports 5a and 5b. FIG. 3 (b)
3A shows a structure in which the fuel injection valve 10 has the same intake port structure as that in FIG. 3A, but is provided offset to the first intake port 5a side.

In either configuration, when the load is low,
The opening operation of the second intake valve 7b in the intake stroke is stopped and the second intake port 5b is closed to allow the intake air to flow into the first intake port 5a while increasing the flow velocity, and thereby the combustion chamber 4 It is configured to generate swirl within.

Further, FIG. 3C shows a case where the intake ports 5a and 5b do not meet on the upstream side thereof and are provided independently of each other in the cylinder head 3. In this configuration, the fuel injection valve 10 is provided in the first intake port 5a, and the swirl control valve 18 is provided in the second intake port 5b. Then, when the load is low, the swirl control valve 18 is closed and the intake air is discharged to the first position.
The intake port 5a is made to flow into the combustion chamber 4 at a high speed to generate swirl in the combustion chamber 4.
Also, instead of providing the swirl control valve 18 described above,
Similar to the configurations of (a) and (b), the opening operation of the second intake valve 7b in the intake stroke may be stopped during a low load. Exhaust ports 6a and 6b are omitted in FIGS. 3 (b) and 3 (c).

In any of the intake port structures, in the intake passage upstream of the intake ports 5a and 5b, as shown in FIG. 2, in order to reduce the pulsation of the intake air due to the opening and closing of the intake ports 5a and 5b. A surge tank 11 having a constant volume is arranged, and a throttle valve for controlling the amount of intake air supplied to the engine E according to the amount of depression of an accelerator pedal (not shown) is provided in the intake passage on the upstream side of the surge tank 11. 12 are provided. Also, the throttle valve 12
An air flow meter 13 for reducing the amount of intake air supplied to the engine E and an air cleaner 14 located at the inlet of the intake system are arranged on the upstream side of. On the other hand, the exhaust ports 6a and 6b communicate with the exhaust passage 15.

As shown in FIG. 1, the engine to which the present invention is applied opens a small amount according to the operating state (especially when it is cold) for a predetermined period from the end of the combustion stroke to the beginning of the intake stroke. The burned gas recirculation valve that recirculates the burnt gas to the intake port is provided, but in the present embodiment, the burned gas recirculation valve is not separately provided, and FIG. In this configuration, the first and second intake valves 7a, 7b
3B, and in the configuration of FIGS. 3B and 3C, only the first intake valve 7a on the side where the fuel injection valve 10 is provided is also used as the burnt gas recirculation valve. Therefore, both the first and second intake valves 7a and 7b, which are opened in the intake stroke, or only the first intake valve 7a are in the operating state for a predetermined period from the end of the combustion stroke to the beginning of the exhaust stroke. Accordingly, the valve operating mechanism 16 of the intake valves 7a and 7b is opened so that a minute amount is opened.
And an actuator 17 for hydraulically driving the valve mechanism 16 is provided.

Furthermore, the first and second intake valves 7a, 7
b or only the first intake valve 7a is opened as a burned gas recirculation valve in a minute amount in synchronization with the fuel injection valve 1
0 is configured to inject fuel, so that the first and second intake ports 5a, 5a,
5b, or only the first intake port 5a, the high-temperature, high-pressure burned gas that recirculates (blows back) at a supersonic speed collides with the fuel spray, causing the coarse fuel droplets to split and collapse.
Promote vaporization. Therefore, it is effective in reducing the adherence of the fuel to the wall surface, and particularly in reducing the amount of HC discharged during cold. Further, since the internal EGR is performed at the same time, the NO _X emission amount is also reduced. Then, in this case, as shown in FIG. 4, by making the injection end timing at which coarse fuel droplets or fuel dripping, which takes time to vaporize, easily occur in the first half of the recirculation period in which the momentum of recirculation is large, The supersonic flow and the injected fuel are effectively collided with each other.

The actuator 17 for hydraulically driving the valve mechanism 16 is controlled together with the fuel injection valve 10 by an output signal from the control unit 20 which reads data of various operating conditions.

The control unit 20 includes an accelerator opening sensor 21 for detecting the opening of the throttle valve 12 whose opening changes according to the amount of depression of an accelerator pedal (not shown), that is, the engine load. Data regarding various operating conditions such as an accelerator opening signal, an intake air amount signal from the air flow meter 13, a crank angle signal from the crank angle sensor 22, and a water temperature signal from the water temperature sensor 23.

The control unit 20 receives these input signals, judges the operating state of the engine E, and outputs a command signal to the actuator 17 of the valve mechanism 16 in accordance with the judgment to control the valve mechanism 16. To do. At the same time, a pulse signal is output to the fuel injection valve 10 to control the injection timing and injection period of the fuel injected from the fuel injection valve 10.

FIG. 5 is an explanatory view schematically showing an example structure of the valve operating mechanism 16 provided in each cylinder.

In FIG. 5, the camshaft 30 on the intake side is shown.
Includes a normal intake cam 31 for lifting the intake valves 7a and 7b in the intake stroke, and a first intake cam 31 on both sides of the intake cam.
And the second blowback cams 32a and 32b are integrally formed with a predetermined interval. The blowback cams 32a and 32b have a cam profile as shown in FIG. 6 (a), and the intake cam 31 has a cam profile as shown in FIG. 6 (b). Then, five rocker arms 34a, 35a, 33, 3 are provided on a rocker shaft (not shown) arranged in parallel with the cam shaft 30.
5b and 34b are swingably arranged in this order. In FIG. 6, BDC ₁ is the combustion bottom dead center, TD
C is the exhaust top dead center, and BDC ₂ is the intake bottom dead center.

The first rocker arm 34a located at the left end in FIG. 5 is always in contact with one blowback cam 32a, and the third rocker arm 33 located at the center.
Always comes into contact with the intake cam 31, and the fifth rocker arm 34b located at the right end is connected to the other blowback cam 3
2b, and these three rocker arms 34a, 33, 34b are not provided with ends for engaging the intake valves 7a, 7b, and are interposed between the rocker arms 34a, 33 adjacent to each other. The mounted second rocker arm 35a always engages with the first intake valve 7a, and the rocker arm 3
A fourth rocker arm 35b, which is provided adjacently between 3 and 34b, is always engaged with the second intake valve 7b.

A first switching means is provided between the rocker arms 34a and 35a for selectively switching between the rocker arms 34a and 35a in an interlocking state or a non-interlocking state.
And a rocker arm 35.
A second pin coupling mechanism 36B, which constitutes a switching means for selectively switching the rocker arms 35a and 33 between the interlocked state and the non-interlocked state, is provided between a and 33, and the rocker arms 33 and 35b are connected to each other. Between the rocker arms 35b and 34b, there is provided a third pin coupling mechanism 36C which constitutes a switching means for selectively switching the rocker arms 33 and 35b between the interlocked state and the non-interlocked state. ,
A fourth pin coupling mechanism 36D is provided which constitutes a switching means for selectively switching the rocker arms 35b and 34b between the interlocking state and the non-interlocking state.

These first to fourth pin coupling mechanisms 36A-
Each 36D includes a pin 37 having a piston function that is hydraulically actuated. These pin coupling mechanism 36A
˜36D will be described in more detail by taking the first coupling mechanism 36A as an example.
4a is slidably fitted into a fitting hole (functioning as a cylinder) 38 that opens on the surface of the rocker arm 35a on the rocker arm 35a side.
Fitting hole 3 into which the pin 37 can be slidably fitted
9 is formed coaxially with the fitting hole 38. The axes of these fitting holes 38 and 39 are parallel to the axis of the camshaft 30. An oil chamber 40 is formed at the bottom of the fitting hole 38, and the oil chamber 40 communicates with an oil passage (not shown) in the rocker shaft through an oil passage 41. This oil passage is a hydraulic pressure supply source (not shown). Connected). Then, when the oil pressure is not supplied to the oil chamber 40, as shown in FIG. 5, the rocker arms 34a and 35a are in a non-interlocking state in which they can independently swing, but when the oil pressure is supplied to the oil chamber 40, A part of the pin 37 is inserted into the fitting hole 39 of the rocker arm 35a, whereby the rocker arms 34a and 35a are coupled via the pin 37 and switched to the interlocking state.

The remaining second to fourth pin coupling mechanisms 36B-3
6D has a similar structure, but as is apparent from FIG. 5, the oil chamber 40 of the second and third pin coupling mechanisms 36B and 36C is formed in the rocker arm 33, and the fourth pin coupling is formed in the rocker arm 34b. The oil chamber 40 of the mechanism 36D is formed.

Next, with respect to the five cases (1) to (5) regarding the operation of the valve mechanism 16 having the above-mentioned structure,
This will be described with reference to FIGS. In each of FIGS. 7 to 11, blowback cams 32 a, 32 are provided.
The lifted state of the intake valves 7a, 7b by b is shown on the left side, and the lifted state of the intake valves 7a, 7b by the intake cam 31 is shown on the right side.

(1) Cold / low negative in the configuration of FIG. 3 (a)
During loading (FIG. 7): first, second and fourth pin coupling mechanism 3
Hydraulic pressure is supplied to the oil chambers 40 of 6A, 36B and 36D, the rocker arms 34a, 35a and 33 are in an interlocked state, the rocker arms 33 and 35b are in an uninterlocked state, and the rocker arm 3 is
5b and 34b are in the linked state. Therefore, both intake valves 7a and 7b are lifted during blowback. Further, in the intake stroke, only the intake valve 7a is lifted, the intake valve 7b is in a rest state, swirl is generated in the combustion chamber 4, and deterioration of combustibility due to burnt gas recirculation is suppressed.

(2) Cold / medium high in the structure of FIG. 3 (a)
During load (FIG. 8): first to fourth pin coupling mechanisms 36A, 3
Oil pressure is supplied to all the oil chambers 40 of 6B, 36C, and 36D, and five rocker arms 34a, 35a, 33, and 3 are provided.
5b and 34b are all in the linked state. Therefore, both during the blowback and during the intake stroke, the intake valves 7a, 7a
Both b are lifted.

(3) Configuration of FIG. 3 (b) and FIG. 3 (c)
Cold and low negative in the configuration excluding swirl control valve 18
When loaded (FIG. 9): first and second pin coupling mechanisms 36A, 36B
Is supplied to the oil chamber 40 of the rocker arm 34a,
35a and 33 are interlocked, rocker arms 33 and 35b
Is in the non-interlocking state, and the rocker arms 35b and 34b are in the non-interlocking state. Therefore, during both the blowback and the intake stroke, only the intake valve 7a is lifted and the intake valve 7a is lifted.
b becomes a rest state, and a swirl is generated in the combustion chamber 4 in the intake stroke.

(4) Structures and diagrams of FIGS. 3 (a) and 3 (b)
3 (c), the temperature in the configuration excluding the swirl control valve 18
During low load (FIG. 10): The oil pressure is supplied only to the oil chamber 40 of the second pin coupling mechanism 36B, and the rocker arm 35a,
33 is the interlocking state, and the others are the non-interlocking states. Therefore,
In the intake stroke, only the intake valve 7a is lifted, the intake valve 7b is in a rest state, and swirl is generated in the combustion chamber 4 without blowback.

(5) At the same temperature / medium / high load (FIG. 11): Oil pressure is supplied to the oil chambers 40 of the second and third pin coupling mechanisms 36B, 36C, and the rocker arms 35a, 33, 35b are brought into an interlocking state. Become. Therefore, no blowback takes place,
In the intake stroke, both intake valves 7a and 7b are lifted.

Table 1 below collectively shows the operating states of the first to fourth pin coupling mechanisms 36A, 36B, 36C, 36D and the intake valves 7a, 7b in the above five cases.

[0079]

[Table 1]

Measures for promoting fuel vaporization and atomization will be described below.

The relationship between the recirculation period T _B of the burnt gas and the fuel injection period T ₁ of the fuel injection valve 10 due to the minute opening of the intake valves 7a, 7b or 7a from the end of the combustion stroke to the beginning of the exhaust stroke will be described. , The fuel injection period T ₁ is the recirculation period T
When it is shorter than _B (T ₁ <T _B ), as shown in FIG. 4, the injection end timing at which coarse fuel droplets or fuel dripping, which requires time for vaporization, is likely to occur, is set to the recirculation period T at which the momentum of recirculation is large. By making it coincide with the first half of _B, the supersonic flow of high temperature gas and the injected fuel are effectively collided.

However, under the operating condition where the fuel injection period T ₁ is longer than the recirculation period T _B , the fuel injection valve 10
It is necessary to set the fuel injection period T ₁ in consideration of the time T required for the fuel spray injected from the above to reach the opening of the intake port to the combustion chamber 4. That is, as shown in FIG. 12, in the case of T _B <T ₁ ≦ T _B + T, the fuel injection is started by the time T before the recirculation start time, so that the period corresponding to T ₁ −T _B The spray can also collide with the reflux to promote the fragmentation and vaporization of the fuel. Also, T
_1> if the T _B + T, when the injection start point to the same manner as above, T ₁ - for spray (T _B + T) corresponding to a period no longer in contact with the reflux, matching the injection end point in the reflux end Then, by injecting the surplus fuel before the start of the recirculation, all of the injected fuel is brought into contact with the recirculation in the intake port, and deterioration of vaporization can be prevented.

Furthermore, the fuel injection period T ₁ is the recirculation period T _B
When it is longer than this, the vaporization of the fuel can be promoted also by providing a throttle means inside the intake port capable of reducing the cross-sectional area of the intake port. For example, as shown in FIG. 13, with respect to the fuel injection valve 10 arranged on the upper wall portion of the intake port 5a, the intake port 5a is provided on the lower wall portion of the intake port 5a on the downstream side of the fuel injection valve 10.
By providing a plate 45 capable of narrowing the cross-sectional area of the plate and changing the angle of the plate 45, the reflux time can be changed even when the reflux amount is constant. This allows
It is possible to control the recirculation amount with respect to the load and the fuel vaporization. Then, in this case, the plate 45 acts as a deflecting plate that deflects the recirculation gas toward the injection port of the fuel injection valve 10, and can promote fuel vaporization.

Alternatively, as shown in FIG. 14, the reed valve 46 which is normally open and does not resist the intake air, but is closed by the recirculation gas in the direction opposite to the intake air is used as a fuel. It may be provided inside the intake port 5a on the upstream side of the injection valve 10. In this case, vaporization can be promoted by increasing the reflux time.

Further, as shown in FIG. 15, the fuel is injected, for example, twice in one cycle so that the first fuel injection period coincides with the burned gas recirculation period and the second fuel is injected. By making the injection period coincide with the overlap period of the valve opening period of the exhaust valves 8a, 8b and the valve opening period of the intake valves 7a, 7b, the recirculation of burnt gas in each period is used to vaporize the fuel. Can be achieved.

Further, the disposition position of the fuel injection valve 10 in the intake port 5a is set to the upstream side of the conventional one, and the fuel injected from the fuel injection valve 10 is supplied to the intake port 5a.
If the fuel injection is ended by the time it reaches the combustion chamber of a, and the burned gas is recirculated after the fuel injection is ended,
All of the fuel spray will come into contact with the reflux gas and promote fuel vaporization.

Further, as shown in FIG. 16, in addition to the first fuel injection valve 10a arranged at the normal position of the intake port 5a, the second fuel injection valve 10 is provided upstream of the intake port 5a.
By providing b, and injecting fuel from both fuel injection valves 10a and 10b at the same time, the fuel injection time is shortened and one recirculation is caused to collide with the fuel spray twice.
It is also possible to vaporize the fuel.

Further, since the recirculated burned gas flows unevenly above the intake port 5a, as shown in FIG. 17A, the raised portion 47 is provided above the opening of the intake port 5a into the combustion chamber 4. Or forming a shroud 48 on the surface of the umbrella portion of the intake valve 5a on the intake port 5a side to narrow the recirculated burned gas flow path above the intake port 5a. As a result, it is possible to make the reflux distribution in the intake port 5a uniform and to vaporize the fuel spray and the fuel adhering to the wall surface.

Contrary to this, on the contrary, by utilizing the property of the recirculated burnt gas which is biasedly flown upward of the intake port 5a,
As shown in FIG. 8, by making the fuel injection direction of the fuel injection valve 10 the upper wall portion of the intake port 5a, the utilization of the recirculated burned gas can be increased and the fuel can be vaporized, and the intake port 5a It is possible to prevent dripping from the lower part. In this case, the fuel injection timing and the recirculation timing are set so that the burned gas is recirculated after the fuel injected from the fuel injection valve 10 adheres to the upper wall surface of the intake port 5a. Reflux may be brought into contact with all of the generated fuel to promote vaporization.

Further, as shown in FIG. 19, the first fuel injection direction is the upper wall portion of the intake port 5a as in the case of FIG.
In addition to the fuel injection valve 10a, the second fuel injection valve 1 in which the fuel injection direction is the opening of the intake port 5a to the combustion chamber 4
0b is provided and fuel is injected from the upwardly directed first fuel injection valve 10a in an operating state in which burnt gas recirculation is performed (when cold), and in an operating state in which burnt gas recirculation is not performed (warm and full The fuel may be injected from the downward second fuel injection valve 10b when the load is applied. 19A shows a case where the first and second fuel injection valves 10a and 10b are arranged in series in one intake port 5a, and FIG.
(B) and (c) show the first and second fuel injection valves 10
This is the case where a and 10b are arranged in parallel. That is, FIG.
9 (b), as in FIG. 3 (a), in the configuration in which the first and second intake ports 5a, 5b merge on the upstream side thereof to form a common intake port 9, the burned gas The first upward fuel injection valve 10a, which operates in the operating state in which the recirculation is performed, is arranged on the common intake port 9 while being offset to the first intake port 5a side, and operates in the operating state in which the burned gas recirculation is not performed. The downwardly directed second fuel injection valve 10b is disposed in the center of the common intake port 9. In addition, FIG.
In (c), as in FIG. 3 (c), in the configuration in which the first and second intake ports 5a, 5b are provided independently of each other, the upward operation in the operating state in which burned gas recirculation is performed is performed. The first fuel injection valve 10a is arranged in the first intake port 5a, and the downward second fuel injection valve 10b which operates in an operating state in which burned gas recirculation is not performed is arranged in the second intake port 5b. ing.

Further, as shown in FIG. 20, the intake port 5a is provided obliquely so that the recirculation revolves in the intake port 5a, and the recirculating recirculation gas causes the fuel injection valve 10 to rotate.
The fuel spray injected from the fuel tank and the fuel adhering to the wall surface of the intake port 5a may be vaporized. Alternatively, as shown in FIGS. 21A and 21B, a recirculation deflecting plate 49 is provided on the surface of the umbrella portion of the intake valve 7a on the intake port 5a side,
The return flow deflection plate 49 may be used to turn the return flow in the intake port 5a. Further, the recirculation deflecting plate 49 may be provided on the intake port 5a side.

By the way, when the burnt gas recirculation control as described above is executed, in the multi-cylinder engine, variations in the burnt gas recirculation amount may occur due to structural variations among the cylinders. Particularly, when the load is low, the combustion condition is bad and the pressure difference between the intake port and the cylinder is large, so that the recirculation amount increases. Therefore, the combustion state of each cylinder is different due to the variation in the recirculation amount, and the engine rotation variation is likely to occur.

Therefore, detection means such as a rotation fluctuation sensor or an in-cylinder pressure sensor is provided to detect the combustion state of each cylinder, and the fuel injection amount is increased for a cylinder that burns slowly (the recirculation amount is large). By shifting the air-fuel ratio to the rich side and accelerating the combustion, it is possible to correct the variation in the combustion state of each cylinder and suppress the rotation fluctuation. However, since this rotation fluctuation is less likely to occur as the load increases, it is better to decrease the correction amount of the injection amount if the load increases.

For cylinders that burn slowly (the amount of recirculation is large),
For a cylinder in which the ignition timing is advanced and the combustion is fast, the fluctuation in rotation can be suppressed also by retarding the ignition timing.

Further, when the cold load is high, the recirculation amount decreases, so that the fuel is less likely to be vaporized. However, an exhaust shutter valve (not shown) is provided in the exhaust manifold of the engine, and when the recirculation amount decreases, By controlling the closing of the exhaust shutter valve, the recirculation amount can be increased. That is, the exhaust shutter valve is used in the high load region as shown in FIG.
As shown in (3), the exhaust pressure increases and a sufficient recirculation amount can be obtained. Therefore, vaporization can be promoted without using a system that opens the intake valve early when the load is high. Further, since EGR is performed at the time of high load, NO _X is reduced, and pumping loss is reduced due to an increase in throttle opening, so that fuel consumption can be improved. And
In this case, it is possible to simplify the control system by determining whether to switch from cold to warm depending on the exhaust temperature and by using the shape memory alloy for the exhaust shutter valve.

Next, when the burnt gas recirculation state is switched to the non-recirculation state, the combustion state changes abruptly.
Torque shock may occur. A method for preventing the occurrence of torque shock will be described below.

The control switching between recirculation of burnt gas and non-recirculation of the burned gas is performed by partial load (throttle opening half open) and full load (WO
T, the throttle opening is fully opened), but when the exhaust shutter valve is provided, for example, as shown in FIG.
As shown in FIG. 3, by gradually opening and closing the exhaust shutter valve, the recirculation amount (internal EGR amount) is gradually changed, so that the occurrence of torque shock due to the switching of control of recirculation of burnt gas and non-recirculation is prevented. can do. Also,
Even when the burned gas recirculation / non-recirculation control is switched based on the engine water temperature, the same exhaust shutter valve control can be performed to prevent the occurrence of torque shock.

Further, the torque shock can be prevented by performing the correction control of the air-fuel ratio at the time of switching the control of recirculation of burnt gas and non-recirculation. That is, as shown in FIG. 24, when the burnt gas recirculation state is switched to the non-recirculation state, the air-fuel ratio is temporarily corrected to the lean side, and then gradually returned to the proper air-fuel ratio, and the recirculation state is restored from the burnt gas non-recirculation state. At the time of switching to the state, the air-fuel ratio is once corrected to the rich side, and then gradually returned to the proper air-fuel ratio, so that the occurrence of torque shock at the time of switching can be prevented.

The burned gas recirculation cam (32 in FIG. 5)
a, 32b) in which the lift timing or the lift amount can be varied, and when the burnt gas recirculation state is switched to the non-recirculation state, the lift timing of the burnt gas recirculation cam is gradually delayed as shown in FIG. When the burnt gas non-recirculation state is switched to the recirculation state, it is possible to prevent the occurrence of torque shock at the time of switching by gradually advancing the lift timing of the burnt gas recirculation cam that has been delayed.

Further, when the burnt gas recirculation state is switched to the non-recirculation state, even if the ignition timing is retarded once and then gradually returned to the proper ignition timing as shown in FIG. Torque shock can be reduced.

Also, when the engine is cold to warm,
When switching control from the burnt gas recirculation state to the non-recirculated state is performed, as shown in FIG. 27, after introducing the same amount of external EGR as the internal EGR amount due to burnt gas recirculation, the external EGR amount is gradually increased. It is possible to prevent a sudden change in the EGR amount by preventing the torque shock from occurring.

Further, when the throttle changes in the opening direction during the recirculation of burnt gas (load increase), the recirculation amount decreases, the vaporization state deteriorates and the HC emission amount increases, or the internal EGR effect decreases and NO External EGR is introduced because _X emission increases. However, the vaporization is not so promoted only by introducing the external EGR. Therefore, as shown in FIG. 28, when the nozzle 50 for introducing the external EGR to the intake port 5a is provided facing the nozzle of the fuel injection valve 10, the fuel spray injected from the fuel injection valve 10 directly contacts the external EGR gas. It is possible to prevent deterioration of vaporization and prevent an increase in HC emissions.

Next, control during acceleration and deceleration will be described.

At the time of acceleration accompanied by temporary injection of fuel, conventionally, the amount of fuel for the temporary injection is increased in anticipation of adhesion of the wall surface of the fuel, which deteriorates fuel efficiency. Therefore, by setting the temporary injection timing to the early stage of the intake stroke in which the high temperature burned gas recirculated by blowback passes through the intake port again, the vaporization of the fuel spray is promoted,
It is possible to reduce the amount of adhering to the wall surface, thereby improving the fuel consumption by reducing the acceleration increase amount (temporary injection pulse width) of the fuel and preventing the increase of the HC emission amount.
In addition, the decrease in the amount of fuel adhering to the wall surface reduces the transport delay of the fuel, so that the acceleration response is also improved.

On the other hand, when the throttle changes to the closing direction for deceleration during the recirculation of the burned gas by blowback or after the recirculation and between the intake starts, the intake air amount decreases and the air-fuel ratio temporarily changes. Becomes richer and the HC emission increases. Therefore, until the fuel is cut while the throttle is closing, the ignition timing is retarded and the exhaust gas temperature is raised to suppress the increase in the HC emission amount.

Next, when the nozzle of the fuel injection valve 10 is directly exposed to burned gas due to blowback, the fuel injection valve 1
Nozzle of 0 may cause clogging. The countermeasure will be described below.

One measure is to make the fuel injection end timing coincide with the recirculation end timing, as shown in FIG.
Further, fuel injection may be performed twice or more in one cycle. In particular, as shown in FIG. 15, it is effective to perform fuel injection during blowback and during intake and exhaust stroke overlaps. Further, as a means for promoting the vaporization of the fuel, when the fuel injection valve is equipped with an air assist means for ejecting air together with the fuel from the nozzle, the assist air pressure is increased to the atmospheric pressure or higher, and during the recirculation of the burned gas, By continuing the air injection, it is possible to prevent the fuel injection valve and the nozzle of the air injection valve from being directly exposed to the burned gas.

By the way, the valve operating mechanism 1 shown in FIGS.
Reference numeral 6 denotes a valve operating mechanism when at least one of the intake valves 7a and 7b is also used as a burnt gas recirculation valve, and at least one intake valve 7a is configured to lift twice in one cycle. .

As shown in FIG. 30, one intake valve 7a is used as a dedicated intake valve and the other intake valve is used to reduce the cam drive loss due to such double lift and prevent the increase of mechanical resistance. May be used as a dedicated burned gas recirculation valve 51. In that case, a burnt gas recirculation port 52 branched from the intake port 5a is provided. Then, the fuel injection valve 10 is disposed on the port wall on the upstream side of the branch portion of the intake port 5a with the burnt gas recirculation port 52 and on the side opposite to the branch portion side. It injects toward the reflux port 52. With such a configuration, the break-up length of the fuel spray can be secured, and the amount of fuel adhering to the wall surface can be reduced.

FIG. 31 also shows a case where a dedicated burned gas recirculation valve 51 is provided. In this case, the dedicated intake valve 7a is arranged at the center with a large diameter, the dedicated burned gas recirculation valve 51 is provided with a small diameter, and a relatively narrow burned gas recirculation port 52 is provided. The fuel injection direction of the fuel injection valve 10 is directed to the burned gas recirculation port 52 as in FIG. Then, at the time of recirculation of burnt gas, fuel is injected from the fuel injection valve 10 in synchronization with the opening timing of the burnt gas recirculation valve 51. The fuel blown back by the recirculation flows into the combustion chamber 4 from the position of the large-diameter intake valve 7a, diffuses in a wide range, and is mixed with air. When the recirculation is stopped, fuel injection is performed in the intake stroke, so that the fuel spray is bent by the intake flow, flows into the combustion chamber 4 from the position of the large-diameter intake valve 7a, diffuses in a wide range, and is mixed with air. It Therefore, the combustibility is also improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the configuration and operation of an engine control device according to the present invention.

FIG. 2 is a sectional view of an engine to which the present invention is applied.

FIG. 3 is a plan view illustrating the arrangement of fuel injection valves with respect to the structure of the intake port of the engine.

FIG. 4 is a characteristic diagram showing the relationship between the fuel injection period and the intake valve opening period when the burnt gas is recirculated.

FIG. 5 is an explanatory diagram showing an example configuration of a valve mechanism.

FIG. 6 is a characteristic diagram showing a valve opening characteristic of an intake valve.

FIG. 7 is an operation explanatory diagram of a valve operating mechanism in the case where both the first and second intake valves are opened during recirculation of burnt gas and only the first intake valve is opened during an intake stroke.

FIG. 8 is an operation explanatory view of the valve operating mechanism when opening the first and second intake valves both during recirculation of burnt gas and during the intake stroke.

FIG. 9 is an operation explanatory view of the valve operating mechanism when only the first intake valve is opened during both recirculation of burnt gas and intake stroke.

FIG. 10 is an operation explanatory view of a valve operating mechanism in a case where only one first intake valve is opened during an intake stroke without opening any intake valve during recirculation of burnt gas.

FIG. 11 is an operation explanatory diagram of the valve operating mechanism in the case where the first and second intake valves are opened in the intake stroke without opening any of the intake valves during recirculation of burnt gas.

FIG. 12 is a characteristic diagram showing the relationship between the fuel injection period and the intake valve opening period during recirculation of burnt gas.

FIG. 13 is an explanatory view showing a state in which a plate for narrowing the intake port is provided on the downstream side of the fuel injection valve.

FIG. 14 is an explanatory diagram showing a state in which a reed valve that restricts an intake port is provided on the upstream side of a fuel injection valve.

FIG. 15 is a characteristic diagram for explaining the fuel injection timing when fuel injection is performed a plurality of times.

FIG. 16 is an explanatory view showing a state in which two fuel injection valves are provided in the intake port.

FIG. 17 is an explanatory view showing a means for returning the recirculated burned gas to the intake port evenly.

FIG. 18 is an explanatory view showing a state in which the fuel injection valve is directed toward the upper wall portion of the intake port.

FIG. 19 is an explanatory view showing a state in which two fuel injection valves having different fuel injection directions are provided.

FIG. 20: 1 of means for swirling burnt gas in intake port
Explanatory drawing showing an example

FIG. 21 is an explanatory view showing another example of means for swirling burnt gas in the intake port.

FIG. 22 is a characteristic diagram showing the relationship between the load and the opening degree of the exhaust shutter valve.

FIG. 23 is a timing chart showing the relationship between throttle valve opening, exhaust shutter valve opening, and recirculation amount.

FIG. 24 is a timing chart used for explaining correction control of the air-fuel ratio at the time of switching between recirculation / non-recirculation.

FIG. 25 is a timing chart for explaining an operation for changing the valve opening timing of the burnt gas recirculation valve when switching between recirculation / non-recirculation.

FIG. 26 is a timing chart for explaining correction control of ignition timing at the time of switching between recirculation / non-recirculation.

FIG. 27 is an external EGR when switching between recirculation / non-recirculation
Characteristic diagram showing changes in quantity

FIG. 28 is an explanatory diagram showing a positional relationship between an external EGR nozzle and a fuel injection valve.

FIG. 29 is a characteristic diagram showing the relationship between the burnt gas recirculation amount and the fuel injection period.

FIG. 30 is an explanatory view showing the arrangement of fuel injection valves when a dedicated burned gas recirculation valve is provided.

FIG. 31 is an explanatory view showing the arrangement of fuel injection valves when a dedicated burned gas recirculation valve is provided.

[Explanation of symbols]

 5a, 5b Intake port 7a, 7b Intake valve 16 Valve mechanism 20 Control unit 30 Cam shaft 31 Intake cam 32a, 32b Burned gas recirculation cam 33 Rocker arm 34a, 34b Rocker arm 35a, 35b Rocker arm 36A-36D Pin Coupling mechanism (switching means) 37 pins 40 oil chamber 51 burnt gas recirculation valve 52 burnt gas recirculation port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F01L 3/06 G 13/00 302 B F02B 31/00 L 31/02 J F02D 41/02 330 E 41/10 335 Z 41/34 F 9247-3G 43/00 301 B J P U Z F02F 1/42 B F02M 25/07 510 B 550 R 580 C 69/00 360 B C G 69/04 P F02P 5 / 15 (72) Inventor Hiroyuki Yamamoto 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (38)

[Claims] 1. A control device for a four-cycle engine having a fuel injection valve in an intake port opened and closed by an intake valve, the control device being small depending on an operating state for a predetermined period from the end of the combustion stroke to the beginning of the intake stroke. An engine control device comprising a burnt gas recirculation valve that opens a predetermined amount to recirculate burned gas to the intake port. 2. The engine control device according to claim 1, wherein the burnt gas recirculation valve is opened when the engine is cold. 3. The engine control device according to claim 1, wherein the intake valve is also used as the burnt gas recirculation valve. 4. The intake valve comprises first and second intake valves provided in a common intake port, and both of the first and second intake valves are also used as the burnt gas recirculation valve. 4. The engine control device according to claim 3, wherein the fuel injection valve is provided in the center of the common intake port. 5. The intake valve comprises first and second intake valves provided in a common intake port, wherein only the first intake valve is also used as the burnt gas recirculation valve and the fuel injection is performed. 4. The engine control device according to claim 3, wherein the valve is provided offset to the first intake valve side. 6. The intake valve comprises first and second intake valves respectively provided in first and second intake ports formed independently of each other, and only the first intake valve is provided. 4. The engine control apparatus according to claim 3, wherein the fuel injection valve is also used as the burnt gas recirculation valve, and the fuel injection valve is provided in the first intake port. 7. The method according to claim 4, wherein when the load is low, the opening operation of the second intake valve in the intake stroke is stopped and the second intake port is closed. Engine controller. 8. The second intake port is provided with a swirl control valve, and when the load is low, the swirl control valve is closed to close the second intake port.
The engine control device described in 1. 9. A first burnt gas recirculation cam, an intake cam, and a second burnt gas recirculation cam are arranged in this order on one camshaft in this order, and are arranged parallel to the camshaft. The rocker shaft, the first rocker arm engaging the first burnt gas recirculation cam, the second rocker arm engaging the first intake valve, and the intake cam. A third rocker arm that matches, a fourth rocker arm that engages with the second intake valve, and a fifth rocker arm that engages with the second burned gas recirculation cam are adjacent to each other. The rocker arms adjacent to each other are selectively arranged to be interlocked or non-interlocked with each other, and first, second, third and fourth switching means are provided. 8. A method according to claim 4, characterized in that Engine controller. 10. The engine control device according to claim 1, wherein the fuel injection by the fuel injection valve is performed in synchronization with the opening timing of the burnt gas recirculation valve. 11. The engine according to claim 1, wherein the end time of fuel injection by the fuel injection valve is set in the first half of the opening period of the burnt gas recirculation valve. Control device. 12. When the fuel injection period of the fuel injection valve is longer than the open period of the burnt gas recirculation valve, the fuel injected from the fuel injection valve is introduced into an opening of the intake port into the combustion chamber. 11. The engine control device according to claim 1, wherein the fuel injection is started before the opening start time of the burnt gas recirculation valve for the time T required to reach the engine. 13. An intake port throttle means is provided in an intake port upstream or downstream of the fuel injection valve, and when the fuel injection period by the fuel injection valve is longer than the open period of the burnt gas recirculation valve, the intake air is taken. 11. The engine control device according to claim 1, wherein the port throttle means is actuated. 14. The engine control according to claim 10, wherein the fuel injection by the fuel injection valve is also performed during the overlap period between the opening period of the exhaust valve and the opening period of the intake valve. apparatus. 15. The engine control device according to claim 1, wherein the fuel injection direction of the fuel injection valve is directed toward the upper wall portion of the intake port. 16. The engine control device according to claim 15, wherein the fuel injection period of the fuel injection valve is set before the opening period of the burnt gas recirculation valve. 17. A first injecting fuel toward an upper wall portion of the intake port in synchronization with an opening timing of the burnt gas recirculation valve in an operating state in which the burnt gas recirculation valve is opened. In the operating state in which the opening operation of the fuel injection valve and the burned gas recirculation valve is stopped, the fuel is injected toward the opening of the intake port to the combustion chamber in synchronization with the intake stroke. 4. The engine control device according to claim 3, further comprising: 18. When the first and second intake valves are provided in a common intake port, the first intake valve is also used as the burnt gas recirculation valve, and the first fuel injection valve is used. 18. The engine control according to claim 17, wherein the common intake port is provided offset to the first intake valve side, and the second fuel injection valve is provided in the center of the common intake port. apparatus. 19. When the first and second intake ports, which are respectively opened and closed by the first and second intake valves, are provided independently of each other, the first intake valve is used as the burnt gas recirculation valve. 18. The engine according to claim 17, wherein the first fuel injection valve is also used as the dual fuel injection valve, and the first fuel injection valve is provided in the first intake port, and the second fuel injection valve is provided in the second intake port. Control device. 20. A means for swirling the burnt gas recirculated to the intake port by opening the burned gas recirculation valve in the intake port, according to claim 1. The engine control device described in 1. 21. The engine control apparatus according to claim 20, wherein the means for swirling the burned gas comprises tilting an intake port through which the burned gas is recirculated. 22. The engine control device according to claim 20, wherein the means for swirling the burned gas comprises a deflecting plate provided in an intake port through which the burned gas is recirculated. 23. The engine according to claim 20, wherein the means for swirling the burned gas comprises a deflector plate provided on the umbrella portion of the intake valve that also serves as the burned gas recirculation valve. Control device. 24. When the engine is a multi-cylinder engine, means for detecting the combustion state of each cylinder is provided, and the air-fuel ratio of the cylinder whose combustion speed is detected to be slow by the detection means is corrected to the rich side. Or advancing the ignition timing of the cylinder.
1. An engine control device according to one of the items. 25. The engine control device according to claim 1, wherein a shutter valve is provided in an exhaust passage of the engine, and the shutter valve is controlled to be closed during a cold high load. 26. A means for reducing torque fluctuation at the time of switching from an operating state in which the burnt gas recirculation valve is opened to an operating state in which the valve opening operation of the burnt gas recirculation valve is suspended. 26. The engine control device according to claim 1, wherein the control device is an engine control device. 27. The engine control apparatus according to claim 26, wherein the torque fluctuation reducing means comprises means for gradually opening a shutter valve provided in an exhaust passage of the engine. 28. The engine control according to claim 26, wherein the torque fluctuation reducing means comprises means for temporarily correcting the air-fuel ratio to the lean side and then gradually returning the air-fuel ratio to the proper air-fuel ratio. apparatus. 29. The engine control device according to claim 26, wherein the torque fluctuation reducing means comprises means for delaying the ignition timing once and then gradually returning the ignition timing to the proper ignition timing. 30. The engine control device according to claim 26, wherein the torque fluctuation reducing means comprises means for gradually delaying the opening timing of the burnt gas recirculation valve. 31. The engine comprises external EGR means for returning exhaust gas from the exhaust passage to the intake passage,
27. The engine control apparatus according to claim 26, wherein the torque fluctuation reducing means comprises means for once introducing a predetermined amount of external EGR amount and then gradually decreasing the external EGR amount. 32. The engine control device according to claim 1, wherein the temporary injection at the time of acceleration by the fuel injection valve is performed at the beginning of the intake stroke. 33. The engine according to claim 1, wherein the ignition timing is retarded in response to the enrichment of the air-fuel ratio due to the reduction of the intake air amount during deceleration. Control device. 34. The end time of fuel injection by the fuel injection valve synchronized with the start time of the burnt gas recirculation valve is made substantially coincident with the closing time of the burnt gas recirculation valve. The control device for the engine according to claim 10. 35. The fuel injection valve is further provided with air assist means for ejecting air together with fuel from the fuel injection valve, and the air assist means recirculates the burned gas after the burned gas recirculation valve is open. 35. The engine control apparatus according to claim 1, wherein air having a pressure equal to or higher than a gas pressure is ejected from the fuel injection valve. 36. The engine control device according to claim 1, wherein a burnt gas recirculation valve is provided separately from the intake valve. 37. The burned gas recirculation valve is provided in a burned gas recirculation port branched from the intake port, and fuel injected from the fuel injection valve traverses the intake port to the burned gas recirculation port. In the operating state in which the fuel injection valve is directed to the burnt gas recirculation port so as to face the intake port, and the burnt gas recirculation valve is opened, the fuel injection valve from the fuel injection valve In the operating state in which the fuel injection is performed in synchronization with the opening timing of the burned gas recirculation valve and the opening operation of the burned gas recirculation valve is stopped, the fuel injection from the fuel injection valve is sucked. 37. The engine control device according to claim 36, which is performed in synchronization with a stroke. 38. The engine control device according to claim 38, wherein the intake valve is formed to have a larger diameter than the burnt gas recirculation valve.