JPS60219434A - Fuel injection controlling device for engine - Google Patents

Abstract

PURPOSE:To prevent rapid change of a transient air-fuel ratio, by providing an operation timing detecting means which detects the operation or stop timing of a second fuel injection valve and a fuel correcting means which corrects an amount of fuel injected from a first fuel injection valve. CONSTITUTION:A first fuel injection valve 13, which injects fuel to an intake air passage during running at a low load and a high load, and a second fuel injection valve 14, which injects fuel during running at a high load, are provided. An operation timing detecting means detects the operation timing and the stop timing of the second fuel injection valve 14. A preventing means, serving as a fuel correcting means, when the second fuel injection valve 14 is rendered operative or brought to a stop, increases or decreases an amount of fuel injected from the first fuel injection valve 13 for a specified time commencing with a current point of time. This enables prevention of rapid change of a transient air-fuel ratio during migration of a low load state and a high load state.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a first fuel injection valve that injects fuel during light loads and high loads, and a second fuel injection valve that injects fuel during high loads. The present invention relates to a fuel injection control device for an engine provided in an intake passage.

(Prior art) Conventionally, as seen in Japanese Patent Application Laid-Open No. 54-84128, at least the intake passage near the engine body is divided into a primary intake passage with a small effective opening area and a secondary intake passage with a large effective opening area.
At low loads, intake air is supplied only from the primary intake passage to promote fuel atomization and to ensure sufficient mixing of air and fuel within the cylinder. Some engines are designed to supply intake air to the engine from the secondary intake passage during high loads to ensure full throttle output.

By the way, in order to control fuel injection with high precision due to the demands for exhaust gas countermeasures and fuel efficiency, it is being considered that fuel injection valves are attached to each of the primary side intake passage and the secondary side intake passage and controlled by a computer. .

However, when using this type of fuel injection control device, from a low load state where intake air is supplied only from the primary intake passage,
When transitioning to a high load state where intake air is supplied from both the secondary and secondary intake passages, fuel adheres to the dry road wall of the secondary intake passage, causing the air-fuel ratio to temporarily become lean, resulting in poor drivability. or, contrary to the above, when transitioning from a high load state to a low load state, the air-fuel ratio may temporarily become lynch due to fuel adhering to the road wall of the secondary intake passage. be.

Therefore, the applicant of this application filed an earlier application (Japanese Patent Application No. 58-5970).
6), an operation timing detection means for detecting the operation timing of the secondary side fuel injection valve, and a fuel correction means for controlling at least one of both fuel injection valves to increase the amount of fuel when the secondary side fuel injection valve is activated. proposed a fuel injection control device with
There is a problem in that control parameters such as calculation of the fuel increase correction amount and processing for attenuating the correction amount increase, making the control system complicated.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems. Provided is a fuel injection control device for an engine that can prevent sudden changes with a control system having a simple configuration (Structure of the Invention) The fuel injection control device for an engine of the present invention injects fuel during light loads and high loads. A fuel injection control device for an engine including a first fuel injection valve and a second fuel injection valve that injects fuel during high load in an intake passage, the device detecting an activation timing or a stop timing of the second fuel injection valve. The fuel injection valve is provided with an operation timing detection means and a fuel correction means for increasing or decreasing the amount of fuel injected from the first fuel injection valve for a certain period of time from the time when the second fuel injection valve is activated or stopped.

Both the first and second fuel injection valves are under the control of a fuel injection amount control means, and the fuel injection control means is constituted by the fuel injection amount control means, operation timing detection means, and fuel correction means. Normally, the basic injection amount from both fuel injection valves is determined according to the input from the air flow sensor, engine speed sensor, and load sensor, and the second fuel injection valve is activated when the low load state changes to the high load state. When injection started, from this point on, the basic injection amount was continuously injected from the first fuel injector for a certain period of time to increase the amount of fuel, and the second fuel injector stopped when the high load state transitioned to a low load state. Sometimes, after a certain period of time has elapsed from this point, the entire basic injection amount is injected from the first fuel injection valve to reduce the amount of fuel, thereby changing from a low load state to a high load state and from a high load state to a low load. This makes it possible to prevent sudden changes in the air-fuel ratio during transition to the current state.

(Effects of the Invention) As is clear from the above, the present invention provides the following effects: lean air and fuel ratio during transition from a low load state to a high load state; In addition to being able to obtain stable torque by preventing the air-fuel ratio from becoming excessively enriched, this method is also achieved through extremely simple control that maintains the operation of the first fuel injector in the state before the transition for a certain period of time from the above transition point. This simplifies both the software and hardware of the fuel injection control means, and there is no delay in fuel correction during the transition, making it highly practical.

(Embodiment) In FIG. 1, reference numeral 1 is an engine body, and intake air is supplied from an air cleaner (not shown) to an air flow chamber 3 in which an air flow sensor 2 is disposed, a throttle channel 5 in which a throttle valve 4 is disposed, The air is supplied to each cylinder (combustion chamber) of the engine through an intake manifold 6 and an intake port 7, and the path from the air cleaner to the intake port 7 constitutes an intake passage 8.

A partition wall 9 is formed in the intake port 7, while a partition wall 10 is formed in the intake manifold 6 and continues to the partition wall 9. The side partition walls 9 and 10 allow the inside of the intake passage 8 to be at least near the engine body l. The primary side intake passages 11 and 2
It is divided into a next side intake passage 12.

The primary side intake passage 11 is provided with a primary side fuel injection valve (first fuel injection valve) 13 for supplying fuel thereto, and the secondary side intake passage is provided with a primary side fuel injection valve (first fuel injection valve) 13 for supplying fuel thereto. A secondary side fuel injection valve (second fuel injection valve) 14 is provided for this purpose. A sub-throttle valve 15 is disposed at the upstream end of the secondary intake passage 12 and operates according to the load.The sub-throttle valve 15 closes when the load is low and the intake air flows through the primary intake passage 12. Flows only to the 2
Intake air is also allowed to flow to the next intake passage 12.

In this way, the sub-throttle valve 15 can be operated in accordance with the load, for example, by mechanically interlocking it with the throttle valve 4, or by operating it in accordance with the intake negative pressure. The primary side fuel injection valve 13 is installed as far upstream as possible in the primary side intake passage 11 in order to promote atomization of the fuel or to achieve sufficient mixing with the intake air. The injection valve 14 is preferably provided as close to the engine body 1 as possible so that fuel can be quickly supplied into the cylinder.

The control unit 16 in FIG. 1 is a microcomputer, and as shown in FIG.
It has the functions of a fuel injection amount control means, a blocking means as a fuel correction means, and a switching means.

The control unit 16 receives input from the air flow sensor 2 and the engine rotation speed sensor 17 as well as an intake negative pressure sensor 18 for detecting engine load. Then, the control unit 16 outputs an output to both the primary and secondary fuel injection valves 13.14.

Next, first, an outline of the fuel injection control performed by the control unit 16 will be explained based on FIG. 4.

The symbol P in the figure indicates a low-load operating state (hereinafter referred to as P zone) in which fuel is injected only from the primary fuel injection valve 13, and the symbol P+S indicates both the primary and secondary fuel injection valves 13 and 14.
This indicates a high-load operating state (hereinafter referred to as the (P+S) zone) in which fuel is injected from the zone.

The P zone and (P+S) zone are set as shown in FIG. 3 using the engine speed and load as parameters, and this map is input to the control unit 16 in advance.

As shown in FIG. 4, in the P zone, the entire basic injection amount is injected from the primary fuel injection valve 13 by applying the basic injection pulse P W So to the primary fuel injection valve 13. In the P+S) zone, in principle, the basic injection amount is divided equally to both the primary side and secondary side fuel injection valves 13 and 14, and half of the basic injection amount is injected. That is, 1
A pulse equal to 1/2 of the basic injection pulse P W So is applied to both the next-side and secondary-side fuel injection valves 13 and 14 .

However, only during a certain period of time To when transitioning from the P zone to the (P 10S) zone, the basic injection pulse PWSO is applied to the primary side fuel injection valve 13, while the secondary side fuel injection valve 14 is the basic injection pulse P W S .

The amount of fuel is increased by applying a pulse of 1/2 of the above, and the air-fuel ratio is maintained at an appropriate level even if fuel adheres to the wall of the secondary intake passage 12.

On the other hand, after the transition from the (P+S) zone to the P zone, the basic injection pulse PWSO is applied to the primary fuel injection valve 13 to inject the entire basic injection amount into the primary fuel injection valve 13. It is injected from the injection valve 13, but (P + S)
Immediately after the transition from the zone to the P zone, only during a certain period of time T1, a basic injection pulse F' W is sent to the primary fuel injection valve 13.
By applying a pulse of 1/2 of S o, the amount of fuel is reduced, and the air-fuel ratio is prevented from becoming excessively rich due to the fuel adhering to the road wall of the secondary intake passage 12, and the air-fuel ratio is maintained at an appropriate level. so that it is maintained.

The fuel injection control as described above will be explained in detail based on the flowchart shown in FIG.

In step PI, the current flag number FLGN is stored in place of the previous flag number FLGB stored in the flag register.

In step P2, the basic injection pulse P W S is calculated by a predetermined calculation formula using the engine rotation speed (ENGrpm) obtained from the output of the engine rotation speed sensor 17 and the intake air amount obtained from the output of the air flow sensor +2.
'o is calculated.

In step P3, the engine rotation speed (ENG
rpm) and the load obtained from the output of the intake negative pressure sensor 18. Based on the zone map shown in FIG.
+S) zone is calculated and the zone is determined.

In step P4, it is determined whether or not the zone is (P+S), and if it is the (P+S) zone, the process moves to step P5, and if it is the P zone, the process moves to step Pj2.

Here, each step (P
5 to pH and P2O) will be explained.

In step P5, the current flag number FLGN
is set to 0.

In step P6, the previous flag number FLGB
It is determined whether or not the current flag number FLGN and the current flag number FLGN are different. If they are not different, that is, the previous flag number
+ S) zone, the process moves to step P8, but if the two are different, that is, the previous time was the P zone and the current one is the (P+3) zone, that is, the transition from the P zone to the (P+S) zone. If it is immediately after switching, the process moves to step P7.

In step P7, the above-mentioned fixed time To is set to the timer T to delay the timing of switching the injection ratio to the total injection amount of the primary side fuel injector 13 when transitioning from the P zone to the (P, +S) zone. .

In step P8, it is determined whether or not the timer T is 0. When the timer T is 0, that is, when the above-mentioned predetermined time To or more has elapsed after the transition to the (P+S) zone, the transition is made to step pH, and the timer T is 0. If not, that is, (P+
S) If the predetermined time To has not elapsed after the transition to the zone, the process moves to step P9.

In step P9, the timer 1' is not 0, and in this case, the count of the timer T is decreased.

In step PlO, the injection pulse PWSp of the primary side fuel injection valve 13 and the secondary side fuel injection valve 1 during a certain period of time To after the transition from the P zone to the (P+3) zone.
The injection pulse PW'Ss of 4 is P W S p -P
W S o + r B A T (invalid time), PW
Ss = 1/2 PWSo + rBAT, and in step P19 the injection pulse PW
Sp and PWSs are the primary side and secondary side fuel injection valves 1, respectively.
Applied to 3.14.

At step pH, the injection pulse PWSp of the primary side fuel injection valve 13 and the secondary side fuel injection valve 14 after a certain period of time To has passed after the transition from the P zone to the (P+3) zone.
The injection pulse P W S s is PWSp = 1 /2
PWSo +rBATSPWSs=PWSp (-'
l /2 PWSo + rBAT), and in step P19, the injection pulses PWSp and PWSs are applied to the primary side and secondary side fuel injector 1, respectively.
Applied to 3.14.

As mentioned above, in the case of being in the (P+S) zone,
After transitioning from P zone to (P -F S) zone, before the elapse of a certain period of time To set in timer T, P6 → P7-
The flow becomes P8→P9→PIO→P19, and after the above-mentioned certain time To has elapsed, the flow becomes P6→P8→pH→P19.

In this way, only during a certain period of time To after the transition from the P zone to the (P+S) zone, the pulse width of all injection pulses of the primary and secondary fuel injection valves 13 and 14 as shown in FIG. will increase, and the amount of fuel will be increased. however,
The fuel injection pulse shown in FIG. 4 does not take into account the invalid time τBAT.

Next, each step (P12 to P18 and P2O) when the zone is in the P zone as a result of the zone determination in step P4 will be described.

In step P12, the current flag number FLG
N is set to 1.

In step P13, the previous flag/7 flag number FL
It is determined whether GB and the current flag number FLGN are different. If they are not different, that is, the previous flag number was also in the P zone, the process moves to step P15, but if they are different, that is, the previous flag number was (P+S). )
zone and is currently in the P zone, i.e. (P +
3) If the zone has just been transferred to the P zone, the process moves to step P14.

In step P14, the above-mentioned fixed time T1 is set to the timer T to delay the timing of switching the injection ratio to the total injection amount of the primary side fuel injection valve 13 at the time of transition from the (P+S) zone to the P zone.

In step P15, it is determined whether or not the timer T is 0. When the timer T is 0, that is, when the above-mentioned fixed time T1 or more has elapsed after moving to the P zone, the process moves to step P18, and the timer T is not 0. In other words, when the predetermined time Tl has not elapsed after the transition to the P zone, the process moves to step P16.

In step P16, the timer T is not O, and in this case, the count of the timer F is decreased.

In step P17, the injection pulse PWSp of the primary fuel injection valve 13 and the injection pulse PWSp of the secondary fuel injection valve 1 during a certain period of time TI after the transition from the (P+S) zone to the P zone are
4 injection pulses P W S s are PWSp = 1 /
2 PWSo+rBAT, PWSs=0, and in step P19, the injection pulses PWSp and PWSs are applied to the primary and secondary fuel injection valves 13 and 14, respectively. .

In step P18, the injection pulse PWSp of the primary side fuel injection valve 13 and the injection pulse PWSs of the secondary side fuel injection valve 14 after a certain period of time Tl has passed after the transition from the (P+S) zone to the P zone are as follows. PWSp=PW
So + rBAT, PWSs = 0, and in step P19, the injection pulses PWSp and PWSs are applied to the primary and secondary fuel injectors 1, respectively.
Applied to 3.14.

As mentioned above, when it is in the P zone, (P+S
) After the transition from zone to P zone, before the fixed time T1 set in timer T has elapsed, P13 → P14 → P15 → P1
6→P17-Pl9 flow, and the above fixed time TI
After the elapse of time, the flow becomes P13-P15→P18→P19. Then, the process moves from step P19 to Pl again and is repeatedly executed.

In this way, only during a certain period of time TI after the transition from the (P+S) zone to the P zone, the pulse width of all injection pulses of the primary and secondary fuel injection valves 13 and 14 is maintained as shown in FIG. This results in a reduction in fuel consumption.

Note that the above embodiment may be partially modified as follows.

First modification: The control unit is configured with an analog computer.

Second modification: The intake passage only needs to be divided into a primary intake passage and a secondary intake passage at least near the engine body. For example, the primary and secondary intake passages are directly downstream of the throttle valve. It may be branched from 1.
Next, the secondary intake passages may be configured completely separately and independently (in this case, the intake boats and the intake valves that open and close them exist independently for the primary side and the secondary side. ).

Third modification = an engine in which intake air is introduced into the combustion chamber from one intake passage without having primary and secondary intake passages, and first and second fuel injection valves are provided in the intake passage. You can. In this case, the effect of the present invention is particularly great when the second fuel injection valve is provided upstream of the first fuel injection valve.

Fourth modification: In the case of a multi-cylinder engine, the first fuel injection valve is arranged in each branch pipe downstream of the intake manifold gathering part to be dedicated to each cylinder, and the second fuel injection valve is installed in the intake manifold. It may also be arranged in a common intake passage upstream of the gathering part and used for each cylinder.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is a block diagram of the control unit shown in FIG. 1, and FIG. 3 is a block diagram of the control unit shown in FIG.
+ S) Diagram showing an example of a map demarcating a zone, 4th
The figure is an operation time chart showing fuel injection pulses, and FIG. 5 is a flow chart showing control by the control unit. l...Engine body, 8...Intake passage, 11...1
Next side intake passage, 12...Secondary side intake passage, 13...1
Next side fuel injection valve, 14... Secondary side fuel injection valve, 16...
·Controller unit. Patent applicant: Toyo Kogyo Co., Ltd.

Claims (1)

[Claims] (1) The first injects fuel during light loads and high loads.
A fuel injection control device for an engine including a fuel injection valve and a second fuel injection valve that injects fuel during high load in an intake passage, the apparatus comprising: an operation for detecting the activation timing or stop timing of the second fuel injection valve; The present invention is characterized in that it is provided with a timing detection means and a fuel correction means for increasing or decreasing the amount of fuel injected from the first fuel injection valve for a certain period of time from the time when the second fuel injection valve is activated or stopped. Engine fuel injection control device