JPS6340930B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is characterized in that an intake passage in the vicinity of at least the engine body is formed by a primary intake passage and a secondary intake passage; The present invention relates to an engine fuel supply control device that supplies intake air to the engine only from a side intake passage, and also supplies intake air to the engine from both intake passages when the load is high.

(Prior art) Conventionally, as seen in Japanese Unexamined Patent Publication 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. formed by,
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, while at high loads intake air is supplied from the secondary intake passage. Some engines also supply intake air to the engine to ensure a predetermined full-throttle output.

By the way, in an engine having a primary side intake passage and a secondary side intake passage, it is better to flow the fuel as well, rather than just flowing intake air through the secondary side intake passage, to reduce the mist of the fuel. This is advantageous in promoting oxidation and mixing with intake air.

However, when the fuel is made to flow through the secondary intake passage, there is a change in the operating mode in which intake air is supplied only from the primary intake passage (hereinafter referred to as low-load operating mode). When shifting to an operating mode in which intake air is supplied using both intake passages (hereinafter referred to as high-load operating mode), the air-fuel ratio temporarily becomes diluted, causing some problems in terms of drivability. It was found that this occurs.

When the cause of the above-mentioned problems was investigated, it became clear that the problem was mainly due to wetting of the inner wall surface of the secondary intake passage. In other words, the inner wall surface of the secondary intake passage is dry because no fuel is flowing during low-load operation, and the fuel that begins to flow through the secondary intake passage when the transition to high-load operation is , not all of it is supplied to the engine with the flow of intake air in a responsive manner, but some of it adheres to the inner wall surface of the secondary intake passage, and this adhesion progresses to the point where it can no longer be attached. It is clear that once the inner wall surface becomes wet, all of the fuel begins to flow toward the engine, so it is clear that there is a shortage of fuel due to the amount of adhesion, and the air-fuel ratio temporarily becomes diluted. It became.

(Object of the invention) The present invention solves the above-mentioned problems.
When transitioning from a low-load operating mode to a high-load operating mode, this prevents deterioration of drivability by preventing temporary dilution of the air-fuel ratio caused by fuel adhering to the inner wall surface of the secondary intake passage. It is an object of the present invention to provide a fuel supply control device for an engine in which the engine fuel supply is controlled.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention, as shown in FIG. a fuel supply timing detection means for detecting when fuel is supplied to the secondary intake passage; a fuel adhesion detection means for detecting fuel adhesion to the inner wall surface of the secondary intake passage;
When fuel is supplied to the secondary intake passage, the fuel adjustment device is controlled so that the amount of fuel is increased and the rate of increase is increased as less fuel adheres to the inner wall surface of the secondary intake passage. A fuel correction means is provided.

As a result, when transitioning from a low-load operating mode to a high-load operating mode, even if the inner wall surface of the secondary side intake passage is dry, the fuel is adjusted in consideration of the degree of wetness of the inner wall surface, that is, the amount of adhesion to the inner wall surface. Since the amount is increased, a mixture having a predetermined air-fuel ratio is supplied to the engine.

The fuel injection valve, which is an example of a component of the fuel adjustment device, is under the control of the fuel injection amount control means, and together with this, the fuel adjustment device is configured, but usually an air flow sensor and an engine rotation speed sensor are included. The basic injection amount from both fuel injection valves is determined according to the input from The output including the fuel component is output from the fuel injection amount control means to the fuel injection valve.

(Example) In Fig. 2, reference numeral 1 indicates 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, and a throttle chamber in which a main throttle valve 4 is disposed. The air is supplied to each cylinder (combustion chamber) of the engine through the air filter 5, the intake manifold 6, and the 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 inside the intake port 7, while
Inside the intake manifold 6 is a partition wall 1 connected to the partition wall 9.
0 is formed, and the interior of the intake passage 8 is divided into a primary intake passage 11 and a secondary intake passage 12 by the partition walls 9 and 10, at least in a portion near the engine body 1.

A primary fuel injection valve 13 for supplying fuel to the primary intake passage 11 is disposed,
Further, a secondary fuel injection valve 14 is disposed in the secondary intake passage for supplying fuel thereto. 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 is closed to allow intake air to flow only to the primary intake passage 11 when the load is low, and opens to allow intake air to flow also to the secondary intake passage 12 when the load is high. In this way, the sub-throttle valve 15 can be operated in accordance with the load by, for example, being mechanically interlocked 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 passage 14 is designed to close the engine body 1 as much as possible so that fuel can be quickly supplied into the cylinder.
It is preferable to provide it nearby.

Reference numeral 16 in FIG. 2 denotes a control unit, ie, a microcomputer, which has the functions of the aforementioned secondary side fuel supply timing detection means, fuel adhesion detection means, fuel correction means, and fuel injection valve control means. This control unit 16 receives input from the air flow sensor 2 and the engine speed sensor 17, as well as
Intake negative pressure sensor 1 for detecting engine load
It is input from 8. Then, the control unit 16 outputs an output to both the primary and secondary fuel injection valves 13 and 14.

In this embodiment, the degree of wetness of the inner wall surface of the secondary side intake passage 12 is detected by the primary side fuel injection valve 1.
The control unit 16 includes a timer function for this purpose. To explain this point in detail, when only the primary side fuel injection valve 13 is operating, there is no fuel flowing into the secondary side intake passage 12.
The fuel adhering to the inner wall surface of the next intake passage 12 is gradually decreasing (drying), and conversely,
When the secondary side fuel injection valve 14 is operating, 2
The amount of fuel adhering to the inner wall surface of the next intake passage 12 gradually increases (wet). Therefore, the degree of wetting of the inner wall surface of the secondary intake passage 12 was determined experimentally in advance by determining the amount of time that only the primary fuel injection valve 13 was operating and the degree of wetting of the inner wall surface of the secondary intake passage 12. If the relationship is investigated, it becomes possible to replace the degree of wetness with the operating time of only the primary side fuel injection valve 13. In addition, the control unit 1
6 also includes a timer function for damping the increment fuel supply.

Here, in the above flowchart, there is a timer (Tret) that counts the time when only the primary side fuel injection valve is operating, and an initial value C ₀ (=f(Tret) of the increased fuel amount which is a function of this timer). ), a damping timer (Tc) for damping the increased amount of fuel,
Increase correction term Ccng (=f(Tc)) which is a function of this
Four factors play a major role. Incidentally, P ₁ to P ₁₇ in the above flowchart indicate each step.

Based on the above premise, control by the control unit 16 will be explained based on the flowchart shown in FIG.

Step P _1As is traditionally done,
Calculate the basic fuel injection amount pulse width PWS ₀ from the intake air amount and engine speed.

Step P ₂ Then, 1 depending on the engine speed and load.
A fuel distribution coefficient D for how to distribute fuel to the next fuel injection valve 13 and the secondary fuel injection valve 14 is determined. The distribution coefficient D is determined by reading from a predetermined map, such as the one shown in FIG. 4, which has been created and stored in advance.
The distribution coefficient D takes a size between 0 and 1, and all values below the α line in Figure 4 (coordinate origin side) are 0.
It is said that

Step _P3 Determine whether the distribution coefficient D is 0 or not (other than 0). Then, when the distribution coefficient D is 0, the process moves to step _P4 (control under low load operation mode),
When the distribution coefficient D is other than 0, the process moves to step _P10 (control under high load operation mode).

Then, from this step P ₃ onwards, the following,
There are four types of flow: , ,. That is, at the time of a low load operation mode (distribution coefficient D is 0, that is, when fuel is supplied only from the primary side fuel injection valve 13), and at the moment when the high load operation mode is switched to the low load operation mode. Yes, if P ₄ →P ₅ →P ₆ →P ₇ .

In the case of P ₄ → P ₈ → P ₉ → P ₆ → P ₇ when in low load operation mode and not at the moment of switching from high load operation mode to low load operation mode.

In high-load operation mode (when the distribution coefficient D is other than 0, that is, both the primary and secondary fuel injectors 1
3, 14) and at the moment of switching from low load operation mode to high load operation mode, and in the case of P ₁₀ →P ₁₁ →P ₁₂ →P ₁₃ →P ₁₄ →P ₇ .

This is a case of high load operation and not at the moment of switching from low load operation to high load operation, P ₁₀ → P ₁₅ → (P ₁₆ ) → P ₁₇ → P ₁₄ → P ₇ .

The above four cases will be explained below.

Step P ₄ (Start of control under low load operating mode) When it is determined in step P ₃ that the distribution coefficient D = 0, this step P ₄ starts control at the moment when switching from low load operating mode to high load operating mode. Determine whether it exists or not.

In this case, step _P5 resets the timer Tret that counts the time that the primary side fuel injection valve 13 is operating. In this case, immediately after the supply of fuel into the secondary intake passage 12 is stopped, that is, when the inner wall surface of the secondary intake passage 12 begins to dry, the starting point of this drying period is The timer Tret is reset. Then, this timer Tret is activated in step _P9 , which will be described later, if the low-load operation mode continues.
We will start counting.

Step _P6 Here, a pulse width is set for the primary side fuel injection valve 13 by adding the invalid fuel injection time Tbat to _{the pulse width PWS 0 set} in Step P1.
Note that since the secondary side fuel injection valve 14 is not operated, its pulse width is 0.

Step _P7 The primary side fuel injection valve 13 is driven with the pulse width set at step _P6 , but since the process has proceeded from step _P6 , the secondary side fuel injection valve 14 is not driven.

Of course, after this step _P7 , the process returns to step _P1 , and a so-called loop is completed.

Step P _8Here , a timer for damping the fuel increase is set.
Reset Tc.

Step P ₉ Timer Tret starts counting the time from when the low load operation mode is entered. After this, the process goes through steps P ₆ and P ₇ as described above, and then steps
A loop is passed to P ₁ .

Step _P10 (Start of control under high load operating mode) This is when it is determined in step _P3 that the distribution coefficient D is other than 0. Here, it is determined whether or not this is the moment when the distribution coefficient D switches to a value other than 0.
If there is a moment of switching, the process moves to step _P11 ; otherwise, the process moves to step _P15 .

In the case of step _P11 , this is the moment when the low-load operation mode is switched to the high-load operation mode, and here, a constant initial value A is given to the timer Tc for damping the fuel increase (the number of seconds for increasing the fuel amount is determined). decide).

Step _P12 Set the initial value C ₀ for fuel increase (how much fuel increase rate). This initial value C ₀ is
As mentioned above, it is a function of the time during which only the primary side fuel injection valve 13 is operating (Tret count number, ie, degree of wetness). And this initial value
C ₀ is created and stored in advance, for example, the fifth
It is given from a graph like the one shown in the figure. As can be understood from Fig. 5, when only the primary side fuel injection valve 13 is driven for a short time (Tret count number is small), the initial value C ₀ is made small (the increase rate is made small). However, if the above time is long, the initial value
Increase C ₀ (increase the rate of increase). and,
After a certain degree of dryness has passed, the same initial value C ₀ is always given.

Step _P13 Sets the increase fuel correction term Ccng (the initial value _C0 itself without being attenuated) at the time of switching.

After this, the loop goes through steps P ₁₄ and P ₇ to step P ₁ , but here, since fuel is supplied from both the primary and secondary fuel injection valves 13 and 14,
In step _P14 , fuel injection pulses PWS ₁ and PWS ₂ for the two fuel injection valves 13 and 14 are calculated, and in step _P7 , both the fuel injection valves 13 and 14 are driven.

In the case of step _P15 , it is determined whether the attenuation correction timer Tc for attenuating the fuel increase is 0 or not.

Step _P16 When the timer Tc is not 0 in step _P15 , in this case, the count of the timer Tc is decreased.

Step P ₁₇ Here, the damping correction term for fuel increase damping is
Ccng is set, but this Ccng is a function of the decay timer Tc. This attenuation correction term Ccng is given by reading a graph shown in FIG. 6, for example, created and stored in advance. As is clear from this graph, f
(Tc) is less than 1, and the timer Tc is counted down at step _P16 as described above, so the extra fuel is attenuated, and when this Tc counts down and reaches 0, the extra fuel is The supply is stopped (decay ends). Of course, if the count of Tc is 0 in step _P15 , the process moves to step _P17 without going through the countdown process in step _P16 .

After this, step P ₁₄ and P ₇ are passed to step P _1.
Turn the loop.

The above is the general flow of the flowchart shown in FIG. 3, but some supplementary explanation will be given regarding the timers Tret and Tc.

First, the time when Tret is reset in step _P5 is the starting point when only the primary fuel injection valve starts operating, and the time during which only the primary fuel injection valve is operating is counted in step _P9 . This is a preliminary act to get started. The count by the timer Tret at step _P9 becomes the basis for calculating how much fuel to increase (fuel increase rate) at step _P12 , which is the initial time of the high-load operation mode.

Further, the timer Tc for damping the fuel increase is set at step _P11 at the initial stage of the high-load operation mode, so that the damping is always performed when the fuel is increased.

Then, by counting Tret and resetting Tc (steps P ₉ and P ₈ ), if low load operation mode and high load operation mode are frequently repeated by changing the fuel increase rate, waste This aims to save fuel by not increasing the amount of fuel. In other words, in such a case, even if there are times when fuel does not flow into the secondary side intake passage, this is a situation in which fuel is immediately supplied from the secondary side fuel injection valve only for a very short period of time. Since this is repeated, the inner wall surface of the secondary intake passage does not dry out, and there is no need to increase the amount of fuel.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

The control unit may also be constituted by a digital computer.

A carburetor may be used as the fuel regulating device.
In this case, to increase the amount of fuel, for example, the diameter of the main jet or main air jet may be manipulated.

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 branched at the main throttle valve, that is, the secondary The main throttle valve may be disposed within the upstream end of the side intake passage, while the auxiliary throttle valve may be disposed within the upstream end of the primary intake passage, or the primary and secondary intake passages may be completely separate and independent. (In this case, an intake port and an intake valve for opening and closing the intake port exist independently for the primary side and the secondary side.)

The fuel adjustment device may not be provided separately for the primary intake passage and the secondary intake passage, but may be provided upstream of the convergence part of the intake passages and used for both the intake passages.

In the case of a multi-cylinder engine, the fuel adjustment device may be disposed at each branch of the intake manifold so as to be dedicated to each cylinder, or it may be disposed at a gathering section of the intake manifold and used for each cylinder.

In order to detect the degree of wetness of the inner wall surface of the secondary side intake passage, for example, the driving pulse for the secondary side fuel injection valve is integrated (of course, the time during which the secondary side fuel injection valve is not driven) is integrated. Alternatively, the degree of wetness may be directly detected using, for example, a humidity sensor.

The increased amount of fuel may be supplied to the secondary intake passage when transitioning to a high-load operating mode. However, as in the example, 1
If separate fuel adjustment devices are provided for the next intake passage and the secondary intake passage to supply increased fuel to the primary intake passage, then during the above transition, the primary intake The passage has a sufficient amount of intake air and a higher flow rate than the secondary intake passage, which is preferable for promoting fuel atomization and achieving sufficient mixing of intake air and fuel. In addition to this, the inner wall surface of the primary intake passage is constantly wet due to the flow of fuel.
The increased amount of fuel is supplied to the engine with good response without substantially adhering to the inner wall surface of the primary intake passage, which is preferable for obtaining a predetermined air-fuel ratio. In other words, when transitioning to a high-load operating mode, the intake air that begins to flow into the secondary intake passage,
Since its specific gravity is lighter than that of fuel, it can be supplied to the engine with good response, so the above-mentioned increase in fuel can be supplied to the engine with good response.
It is extremely effective in obtaining a predetermined air-fuel ratio.

Especially when the opening of the sub-throttle valve is small,
Since the flow rate of the intake air flowing through the secondary intake passage is slow, it is preferable to supply the increased amount of fuel to the primary intake passage in order to promote atomization of the fuel within the intake passage.

(Effects of the Invention) As is clear from the above description, the present invention can prevent temporary dilution of the air-fuel ratio when transitioning from a low-load operating mode to a high-load operating mode; Therefore, the above-mentioned transition is carried out smoothly and good drivability can be obtained.

In particular, in the present invention, since the amount of fuel is increased according to the degree of wetting (the degree of fuel adhesion) on the inner wall surface of the secondary side intake passage, the amount of fuel can be increased to the minimum necessary, which also improves fuel efficiency. This is preferable in order to accurately obtain a predetermined air-fuel ratio.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is an overall configuration diagram showing one embodiment of the invention, and FIG.
FIG. 4 is a flowchart showing the control of the control unit shown in FIG. FIG. 6 is a diagram showing an example of the relationship between the time when only the primary side fuel injection valve is operating and the fuel increase rate, and FIG. 6 is a diagram showing an example of the relationship between the count number of the damping timer and the damping rate. be. 1...Engine body, 8...Intake passage, 11...
...Primary side intake passage, 12...Secondary side intake passage, 1
3... Primary side fuel injection valve, 14... Secondary side fuel injection valve, 16... Control unit.

Claims (1)

[Claims] 1. At least the intake passage near the engine body is 1.
It is formed by an intake passage on the next side and an intake passage on the secondary side, and when the load is low, intake air is supplied to the engine only from the above-mentioned primary intake passage, and when the load is high, intake air is supplied to the engine from both intake passages. A fuel supply control device for an engine configured to supply fuel to the engine, the fuel adjustment device adjusting fuel supplied to both intake passages, and a fuel supply timing unit detecting when fuel is supplied to the secondary intake passage. a detection means; a fuel adhesion detection means for detecting fuel adhesion to an inner wall surface of the secondary intake passage; when fuel is supplied to the secondary intake passage;
and a fuel correction means for controlling the fuel adjustment device so as to increase the amount of fuel and increase the rate of increase as the fuel adhesion to the inner wall surface of the secondary side intake passage increases. Fuel supply control device.