JPH06193496A - Engine control device - Google Patents

Abstract

PURPOSE:To prevent torque shock which occurs when the operation is changed over from a means for directly feeding fuel into an engine cylinder into a means for feeding fuel into an intake air passage in the engine, by carrying out the change-over after the intake air volume is decreased but the fuel volume is increased. CONSTITUTION:A first fuel supply means 34 includes an injector 18 for injecting and feeding fuel directly into a cylinder 4 of an engine 1, and a second fuel supply means includes an injector 14 for injecting and feeding fuel into an intake-air passage 9 in the engine 1. Further, both fuel supply means 34, 26 are changed over under control. In this control device, when the operation is changed over from the first fuel supply means 34 into the second fuel supply means 26, the intake air volume is decreased but the fuel volume is increased in such a condition that the first fuel supply means 34 is operated. Thereafter, the operation is changed over into the second fuel supply means 26, and the change-over control means 42 is controlled. With this arrangement, it is possible to prevent torque shock which occurs when the fuel supply is changed over.

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 control device for switching fuel injection into a cylinder of an engine and fuel injection into an intake passage in accordance with an operating state of the engine. Regarding

[0002]

2. Description of the Related Art Conventionally, as a control device for an engine of this type, as shown in Japanese Patent Laid-Open No. 63-159614, fuel is injected into the cylinder of the engine and fuel is injected into the intake passage. When switching to manifold injection according to the operating state of the engine, in the in-cylinder injection state, close the throttle valve so that the air-fuel ratio is almost the same as the manifold injection state after switching, and then switch to both injection states. It is known that the air-fuel ratio is adjusted to be substantially the same, and the fluctuation of the output torque due to the switching is suppressed to reduce the torque shock.

[0003]

However, since the combustion state of the fuel differs between the in-cylinder injection and the manifold injection due to the difference in the air utilization rate in the combustion chamber, the air-fuel ratios are made substantially the same as in the conventional case. However, there is a difference in output torque, and it is difficult to effectively prevent the torque shock due to switching, and there is room for improvement.

The present invention has been made in view of the above points, and an object thereof is to effectively reduce the torque shock caused by the switching by changing the control method when switching between in-cylinder injection and manifold injection. To try.

[0005]

To achieve this object, the present invention utilizes the fact that the rich limit of the air-fuel ratio in the in-cylinder injection state is wider than that in the manifold injection state, and the fuel supply amount at the time of switching is utilized. Was changed to match the air utilization rate, and in that state, the change in the throttle opening due to the switching was reduced.

That is, as shown in FIG. 1, in the invention of claim 1, the first fuel supply means 34 for directly injecting and supplying the fuel into the cylinder 4 of the engine 1 and the intake passage 9 of the engine 1.
Second fuel supply means 26 for injecting and supplying fuel to
In an engine control device in which the operation of the first and second fuel supply means 34, 26 is controlled to be switched according to the operating state of the engine 1, the first fuel supply means 34 transfers to the second fuel supply means 26. When switching the operation, the switching control means 42 for controlling to switch to the operating state of the second fuel supply means 26 after reducing the intake air amount and increasing the fuel supply amount in the operating state of the first fuel supply means 34. Set up.

Further, in the invention of claim 2, when the operation of the switching control means 42 is switched from the second fuel supply means 26 to the first fuel supply means 34, the second fuel supply means 26 moves to the first fuel supply means. After switching to the operating state of No. 34, the intake air amount is increased and the fuel supply amount is decreased.

[0008]

With the above construction, in the invention of claim 1, the operation is switched from the first fuel supply means 34 to the second fuel supply means 26 in accordance with the operating state of the engine 1, that is, the fuel is supplied to the cylinder of the engine 1. When switching from the in-cylinder injection state in which the direct injection is supplied into 4 to the manifold injection state in which the injection is supplied to the intake passage 9, by the control of the switching control means 42,
First, the intake amount is reduced and the fuel supply amount is increased in the operating state of the first fuel supply means 34, and then the operating state of the second fuel supply means 26 is switched. As described above, in the state where the first fuel supply means 34 is operated and the in-cylinder injection is performed, the intake air amount is decreased and the fuel supply amount is increased at the same time. Therefore, the increase in the fuel supply amount causes The air utilization rate becomes the same as the state in which the second fuel supply means 26 operates and the manifold injection is performed after the switching. Therefore, the intake air amount can be reduced and the fluctuation of the throttle opening can be reduced while the output torque is increased by matching the air utilization rate with the state after switching, and the torque shock at the time of switching from in-cylinder injection to manifold injection is effective. Can be reduced to At that time, in the in-cylinder injection state due to the operation of the first fuel supply means 34, since the air utilization rate is low, the engine 1 will not misfire even if the fuel supply amount is increased.

On the other hand, in the invention of claim 2, when the operation is switched from the second fuel supply means 26 to the first fuel supply means 34, the switching control means 42 first supplies the first fuel from the second fuel supply means 26. The operation state is switched to the means 34, and thereafter the intake amount is increased and the fuel supply amount is decreased. In this case, after the manifold injection state is switched to the in-cylinder injection state, the fuel is reduced and corrected in the in-cylinder injection state, so the air utilization rate and the output torque are the same before and after the switching, and the manifold injection to the in-cylinder injection is performed. It is possible to reduce the torque shock at the time of switching to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings starting from FIG. FIG. 9 shows the overall configuration of an embodiment of the present invention, in which 1 is a two-cylinder rotary piston engine, and this engine 1 has two rotor housings 2 and 2 (only one is shown) having a trochoidal surface on the inner circumference. , And three side housings 3, 3, ... (Only one is shown) joined to both sides of each rotor housing 2 and surrounded by the two housings 2, 3 to provide two cylinders 4, 4 (1 Each of the cylinders 4 accommodates a rotor 6 that divides the interior of the cylinder 4 into three working chambers 5, 5 ,. Each of the rotors 6 is supported by an output shaft 7 so as to be eccentrically rotatable, and the eccentric rotation of the rotor 6 causes the working chambers 5 to sequentially perform intake, compression, combustion, and exhaust strokes. Is driven to rotate.

In the side housing 3 between the rotor housings 2 and 2, the working chamber 5 in the intake stroke of each cylinder 4 is provided.
An intake port 8 forming a downstream end portion of an intake passage 9 for supplying intake air to the is opened. The upstream end of the intake passage 9 is connected to an air cleaner 10. The intake passage 9 is driven by an air flow meter 11 for detecting the intake air amount and an actuator 13 such as a stepping motor in order from the air cleaner 10 toward the downstream side. An electric throttle valve 12 that adjusts the opening degree of the intake passage 9 and a manifold injection injector 14 that injects fuel into the intake passage 9 are provided.

On the other hand, in each rotor housing 2, an exhaust port 15 constituting an upstream end of an exhaust passage 16 for exhausting exhaust gas in the working chamber 5 in the exhaust stroke of each cylinder 4 is provided.
And an O2 sensor 17 for detecting the oxygen concentration in the exhaust gas is provided in the exhaust passage 16.

Further, each of the rotor housings 2 includes:
A main injector 18 for in-cylinder injection that directly injects fuel into the working chamber 5 in the compression stroke, a spark plug 20 for igniting intake air in the working chamber 5 in the combustion stroke, and ignition of the tip of the spark plug 20. A pilot injector 19 for in-cylinder injection for injecting and supplying fuel to the engine is attached.

The manifold injector 14
Is connected via a fuel supply passage 23 to a low-pressure fuel pump 22 that discharges fuel at a relatively low discharge pressure arranged in the fuel tank 21, and the injector 14, the fuel supply passage 23, and the low-pressure fuel pump 22 A second fuel supply device 26 is configured to inject and supply the fuel in the fuel tank 21 to the intake passage 9 of the engine 1 (hereinafter, may be abbreviated as MI injection in this embodiment). Reference numeral 24 is a fuel return passage for returning the fuel not injected by the manifold injector 14 to the fuel tank 21, and a regulator 25 for maintaining a constant differential pressure between the fuel injection pressure and the intake pressure is provided in the fuel return passage 24.

The main and pilot injectors 18 and 19 for in-cylinder injection are connected to the fuel pump 22 in the fuel tank 21 via fuel supply passages 27 and 28, respectively. Each fuel supply passage 27, 28
The transmission belt 3 is connected to the output shaft 7 of the engine 1.
A high-pressure fuel pump 29, 30 that is driven through the engine 5 to discharge high-pressure fuel is provided. The main and pilot injectors 18, 19, the fuel supply passages 27, 28, and the high-pressure fuel pump 29, 30 are used to drive the engine 1 The first fuel supply device 34 is configured to directly inject and supply the fuel into each of the cylinders 4 (hereinafter, may be simply referred to as DI injection in this embodiment). Reference numerals 31 and 32 are regulators arranged in the fuel supply passages 27 and 28, respectively, and control the fuel injection pressure of the injectors 18 and 19 in response to a control signal from a control unit 41 described later. Reference numeral 33 is a fuel return passage for returning the fuel not injected by the injectors 18 and 19 and the fuel from the regulators 31 and 32 to the fuel tank 21.

Actuator 1 of the throttle valve 12
3, injectors 18, 19, high-pressure fuel injection pump 2
9, the regulator 31, 32 is the control unit 4
1, the operation is controlled. An output signal of the air flow meter 11, an output signal of the O2 sensor 17, an accelerator opening signal, and an engine speed N signal are input to the control unit 41. The operation state of the engine 1 is determined, and the operation of the first and second fuel supply devices 34, 26 is switched and controlled according to the operation state.

That is, the control operation of the control unit 41 will be described with reference to the flowcharts shown in FIGS. 3 to 5. First, the operating state of the engine 1 is read in step S1, and the operating state of the engine is in the fuel injection region in step S2. Determine whether or not. This fuel injection region is, as shown in FIG. 8, a rotational speed N of the engine 1.
The fuel supply to both cylinders 4 and 4 is stopped in the high speed range shown by the region V in FIG. 8 and is supplied in the other regions.
Further, in the region IV, the fuel is supplied to only one cylinder 4 and the fuel supply to the other cylinder 4 is stopped. The high load region shown by region I in FIG. 8 is a manifold injection region where fuel is injected into the intake passage 9 by the operation of the second fuel supply device 26, and the low speed low load region shown by region II is the first fuel supply device. This is an in-cylinder injection region (direct injection region) in which fuel is directly injected into each cylinder 4 by the operation of 34. Area III
Is an operation switching region of the first and second fuel supply devices 34 and 26. The region VI is a feedback region in which the air-fuel ratio is fed back based on the output signal of the O2 sensor 17.

When the determination in step S2 is NO, the process proceeds to step S35 which will be described later, but when the determination is YES, it is determined in step S3 whether the flag F3 is F3 = 1. If this determination is NO at F3 = 0, the operation proceeds to step S29, which will be described later, but if YES at F3 = 1 the operation proceeds to step S4 to determine whether the flag F2 is F2 = 1. If the determination is YES at F2 = 1, the process proceeds to step S5 to determine whether the flag F1 is F1 = 1. When this determination is NO at F1 = 0, the process proceeds to step S15 described later, but when YES at F1 = 1 the process proceeds to step S6 and the first and second fuel supply devices 34, 2
It is determined whether or not it is the switching area of No. 6 (area III in FIG. 8).
When this judgment is YES, the routine proceeds to step S7, where it is judged whether the flag F5 is F5 = 0. This judgment is F5
If NO = 1, the process proceeds to step S24 described later,
If YES in F5 = 0, the flow advances to step S8 to determine whether the flag F4 is F4 = 0. This judgment is F
If NO in 4 = 1, the process proceeds to step S25 described later,
If YES at F4 = 0, the routine proceeds to step S9, where it is judged if the previous cylinder injection (DI injection) was performed. When this determination is YES, steps S10 to S19
First, in step S10, the switching DI injection amount Q3 is calculated.

Specifically, first, as shown in FIG. 6, an injection amount Q2 that can output the same torque as the torque at the start of control is obtained from the map as a function of the injection amount Q1 (Q2 = f
(Q1)), this injection amount Q2 is multiplied by a coefficient K, and when switching D
The I injection amount Q3 (= K × Q2) is calculated. Above coefficient K
Takes into account the time elapsed from the start of control to the time of switching,
It is set as a function of the change amount ΔT of the throttle opening for one cycle when the throttle valve 12 changes at the fastest speed, and increases in proportion to the increase of the accelerator pedal depression speed as shown in FIG. .

In the next step S11, the switching DI throttle opening T3 is determined by a map. After that, the process proceeds to step S12 to calculate the switching MI fuel injection amount Q4 (= K × Q1) by multiplying the fuel injection amount Q1 by the coefficient K, and the switching throttle opening T4 is determined from the map in step S13. . Further, in step S14, the engine speed N, the fuel injection amounts Q1 and Q3, and the throttle opening T1.
, T3 based on one cycle of fuel change ΔQ = f
(N, Q1, Q3) and the change ΔT = f (N, T1, T3) in one cycle of the throttle opening are calculated. The one cycle change ΔQ of the fuel has a value corresponding to the one cycle change ΔT of the throttle opening.

After that, the process proceeds to step S15, where the change amount ΔQ is added to the fuel injection amount Q1 to add a new fuel injection amount Q.
In addition to setting 1, the change amount ΔT is subtracted from the throttle opening T1 to set a new throttle opening T1. Next, the routine proceeds to step S16, where the set fuel injection amount Q1 is Q1 = Q3 and the throttle opening T1 is T1.
= T3 is determined. If the determination is NO, the flag F1 is set to F1 = 0 and the flag F2 is set to F2 = 1 in step S17. If the determination is YES, the flag F1 is set to F1 = 1 in step S18.
Each proceeds to step S19. In this step S19, D
After setting the final fuel injection amount Q in the I injection to Q = Q1 and the final throttle opening T to T = T1, the process proceeds to step S34.

If the determination in step S4 is F2 = 0, NO.
If, then the process proceeds to step S20, where the final fuel injection amount Q is Q
= Q4, and the final throttle opening T is set to T = T4, and in the next step S21, the flag F2 is set to F2 =
After setting 0 and setting the flag F5 to F5 = 1, the process proceeds to step S34.

If it is determined to be NO in step S6,
In step S22, both flags F5 and F6 are set to F.
After setting 5 = F6 = 0, the process proceeds to step S23, and it is determined whether the engine 1 is in the light load region. This judgment is N
When O, the process proceeds to step S24 when the determination in step S7 is NO and performs MI injection, while when the determination is YES, proceeds to step S25 when the determination in step S8 is NO and performs DI injection. . After these steps S24 and S25, the process proceeds to step S34.

Further, when the determination in step S9 is NO, the process proceeds to steps S26 to S33. First, in step S26, the switching DI injection amount Q3 is calculated from the map as a function of the injection amount Q4 (Q3 = f (Q4
)). Then, in step S27, the switching DI throttle opening T3 is determined by a map. After that, the routine proceeds to step S28, where the engine speed N, the fuel injection amount Q1,
Based on Q3 and the throttle opening T1, T3, the change ΔQ = f (N, Q1, Q3) in one cycle of fuel and the change ΔT = f (N, T1, T3 in one cycle of throttle opening
) And are respectively calculated.

Thereafter, when the determination in step S3 is NO, the process proceeds to step S29, in which the change amount ΔQ is subtracted from the fuel injection amount Q3 to set a new fuel injection amount Q3, and the throttle opening T3 is set to that value. A new throttle opening T3 is set by adding the change amount ΔT. Next, in step S30, it is determined whether the throttle opening T is fully open. If the determination is NO, the flag F4 is set to F4 = 1 and the flag F3 is set to F3 = 0 in step S31, and if the determination is YES, the flag F3 is set to F3 = 1 in step S32, and then the respective steps are performed. Proceed to S33. In this step S33, the final fuel injection amount Q in DI injection is set to Q = Q3, and the final throttle opening T is set to T.
After setting each to T3, the process proceeds to step S34.

In step S34, fuel injection is executed,
The ignition key switch is turned on in the next step S35.
It is determined whether or not it is in a state. If this determination is NO, the process ends, but if YES, the process returns to step S1.

In this embodiment, the first fuel supply device 3 is executed by steps S6 to S34 in the above flow chart.
When the operation is switched from 4 to the second fuel supply device 26, the intake air amount is reduced and the fuel supply amount is increased in the operation state of the first fuel supply device 34, and then the operation state of the second fuel supply device 26 is switched. On the other hand, when the operation is switched from the second fuel supply device 26 to the first fuel supply device 34, on the contrary, after switching from the second fuel supply device 26 to the operation state of the first fuel supply device 34, the intake air Switching control means 4 for controlling the fuel supply amount to increase and the fuel supply amount to decrease.
2 are configured.

Therefore, in the above embodiment, the operating region of the engine 1 is determined during the operation of the engine 1, and the main and pilot injectors 18 for in-cylinder injection into the cylinders 4 of the engine 1 are determined in accordance with the operating region. In-cylinder injection in which fuel is directly injected from 19 and manifold injection in which fuel is injected from the manifold injector 14 into the intake passage 9 are selected. That is, when the operating region of the engine 1 is in the region II shown in FIG. 8, the first fuel supply device 34 operates and the main and pilot injectors 18 and 19 for in-cylinder injection directly into the working chamber 5 of each cylinder 4. Fuel is injected. Further, in the region I, the second fuel supply device 26 operates to inject fuel from the manifold injection injector 14 into the intake passage 9 downstream of the throttle valve 12 to perform manifold injection.

Then, when the engine 1 is in the switching region of the region III between the above two regions I and II, the previous fuel injection state is judged, and if it is the in-cylinder injection state, the fuel injection state is in the cylinder. It is determined that the injection is switched to the manifold injection. At this time, as shown in FIG. 2 (note that the broken line in FIG. 2 shows the conventional state in which the intake air amount is simply changed), first, with the first fuel supply device 34 in the operating state, the actuator is first operated. The throttle valve 12 is throttled by 13 to reduce the intake air amount, and at the same time, the fuel injection amount from the in-cylinder injectors 18 and 19 is increased, and thereafter the second fuel supply device 26 is switched to the operating state. In this way, the intake air amount is reduced and the fuel injection amount is increased at the same time when the in-cylinder injection is being performed. Therefore, due to the increase in the fuel injection amount, the air injection rate of the engine 1 is switched and the manifold injection is performed. The output torque can be increased by matching the air utilization rates. Therefore, the intake air amount can be reduced to reduce the fluctuation of the throttle opening, and the torque shock at the time of switching from in-cylinder injection to manifold injection can be effectively reduced.

At this time, in the in-cylinder injection state due to the operation of the first fuel supply device 34, since the air utilization rate is low, even if the fuel supply amount is increased, overrich does not occur and the engine 1 misfires. Can be prevented.

On the other hand, even when the engine 1 is in the switching region of the region III, if the previous fuel injection state is the manifold injection state, it is determined that the fuel injection state is switched from the injection manifold injection to each cylinder 4. To be done. At this time, conversely to the above, first, the operation is switched from the second fuel supply device 26 to the first fuel supply device 34, and thereafter the intake air amount is increased by the increase of the throttle opening and the in-cylinder Injection injectors 18, 1
The fuel injection amount from 9 decreases. At this time, since the fuel is reduced and corrected in the in-cylinder injection state after the manifold injection state is switched to the in-cylinder injection state, the air utilization rate and the output torque are the same before and after the switching, so that the manifold injection to the in-cylinder state is performed. It is possible to reduce the torque shock when switching to injection.

In the above embodiment, the case of the two-cylinder rotary piston engine 1 has been described, but the present invention can be applied to other engines.

[0033]

As described above, according to the invention of claim 1, the first fuel supply means for directly supplying the fuel into the cylinder of the engine and the second fuel supply means for supplying the fuel to the intake passage of the engine. In the case of switching between and in accordance with the operating state of the engine, when switching from in-cylinder injection by the first fuel supply means to manifold injection by the second fuel supply means, the intake amount is reduced in the operating state of the first fuel supply means. By increasing the amount of fuel together with this, and then switching to the operating state of the second fuel supply means, the fact that the rich limit in the in-cylinder injection state by the first fuel supply means is wide is utilized, and the fuel amount increase correction is performed. The torque is increased by matching the air utilization rates before and after the switching, and the throttle opening in the manifold injection state is approached in the in-cylinder injection state. Rukoto can, it is possible to effectively reduce torque shock when switching to manifold injected from in-cylinder injector.

According to the second aspect of the invention, when switching from the manifold injection by the second fuel supply means to the in-cylinder injection by the first fuel supply means, the operation is performed after switching to the operating state of the first fuel supply means. In this state, by increasing the intake air amount and decreasing the fuel amount, the air utilization rate before and after the switching is matched to reduce the torque, and the throttle opening in the manifold injection state is adjusted in the in-cylinder injection state. It is possible to bring them closer to each other, and it is possible to effectively reduce the torque shock at the time of switching from the manifold injection to the in-cylinder injection.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a characteristic diagram showing changes in the intake air amount, the fuel injection amount, and the air utilization rate when switching the fuel injection state.

FIG. 3 is a flowchart showing a front part of a signal processing operation performed in the control unit according to the embodiment of the present invention.

FIG. 4 is a flowchart showing an intermediate part of a signal processing operation.

FIG. 5 is a flowchart showing a rear part of the signal processing operation.

FIG. 6 is a characteristic diagram showing a change in engine output torque due to correction of a fuel injection amount.

FIG. 7 is a characteristic diagram showing a characteristic of a coefficient that changes according to an accelerator depression speed.

FIG. 8 is a characteristic diagram of a map showing a fuel injection state set according to the operating state of the engine.

FIG. 9 is an explanatory diagram showing an overall configuration of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 engine 4 cylinder 9 intake passage 12 throttle valve 14 manifold injection injector 18 in-cylinder injection main injector 19 in-cylinder injection pilot injector 26 second fuel supply device (second fuel supply means) 34 first fuel supply device (first) 1 fuel supply means) 41 control unit 42 switching control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiro Sou 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (2)

[Claims] 1. A first fuel supply means for injecting and supplying fuel directly into a cylinder of an engine, and a second fuel supply means for injecting and supplying fuel to an intake passage of the engine, wherein: In an engine control device for switching and controlling the operations of the first and second fuel supply means, when the operation is switched from the first fuel supply means to the second fuel supply means, the first fuel supply means is in an operating state. An engine control device comprising switching control means for controlling the second fuel supply means to switch to an operating state after reducing the intake air quantity and increasing the fuel supply quantity. 2. The engine control device according to claim 1, wherein the switching control means switches from the second fuel supply means to the first fuel supply means when the operation is switched from the second fuel supply means to the first fuel supply means. After switching to an operating state, the engine control device is configured to perform control so as to increase the intake air amount and decrease the fuel supply amount.