JPS60108529A - Suction device of engine - Google Patents

Abstract

PURPOSE:To prevent overleaning of fule-air mixture during acceleration operation, by a method wherein a first expansion chamber is located down a first suction passage from the first throttle valve, and a second expansion chamber is independently located in said expansion chmaber down a second suction passage from a second throttle valve. CONSTITUTION:Suction air is fed at an entire operation range through a first suction passage 7a, and the suction air is fed at a high suction amount range through a second suction passage 7b. A first expansion chamber 7c is formed down the first suction passage 7a from a second throttle valve 10, and a second expansion chmaber 7d is located, independently from each other, down the second suction passage 7b froma second throttle valve 11. A first injection valve 12, injecting fuel in an entire operating range, is located in the first suction passage 7a, and a second injection valve 13, injecting fuel in a high suction amount range, is situated in the second suction passage 7b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an intake system for an engine.

(Prior art) Two intake passages are provided for each cylinder of the engine, a throttle valve and a fuel injection valve are arranged in each intake passage, and the opening degree of each throttle valve is adjusted according to the operating conditions such as engine load. An intake system that supplies intake air from the first intake passage in the entire operating range including the low intake air volume range, and supplies intake air in the high intake air volume range from the second intake passage is disclosed, for example, in Japanese Patent Application Laid-open No. 51-1202
It is publicly known as seen in No. 5.

In the above-mentioned intake system, the first
Also, when the second throttle valve opens suddenly, the intake air amount increases rapidly as the throttle valve opens, but there is a delay in fuel supply, and even if you try to accelerate and increase the amount of fuel, it will be temporary. Acceleration displacement occurs due to the lean air-fuel mixture being supplied to the engine. In addition, when decelerating from a high intake air volume region to a low intake air amount region, that is, when decelerating suddenly, the first and second
The throttle valve suddenly closes, the negative pressure in the intake passage downstream of the throttle valve rapidly increases, and the suction of fuel adhering to the passage wall supplies an over-rich air-fuel mixture. During deceleration (half deceleration), the fuel adhering to the passage wall surface and the fuel from the fuel injection valve are temporarily sucked into the combustion chamber without being vaporized or atomized due to the decrease in the intake flow velocity. May adversely affect flammability.

(Object of the Invention) In view of the above-mentioned circumstances, it is an object of the present invention to provide an intake system for an engine that is capable of preventing over-richness during acceleration and deceleration.

(Toganari of the Invention) An intake system for an engine according to the present invention is provided with a first throttle valve and a first injection valve in a first intake passage that supplies intake air to each cylinder in all operating ranges including a low intake air amount range. In addition, a second throttle valve and a second injection valve are provided in the second intake passage that supplies intake air in a high intake air amount region, and a first expansion valve is provided downstream of the first throttle valve in the first intake passage. In addition, a second expansion chamber is provided downstream of the second throttle valve in the second intake passage independently of the first expansion chamber.

(Effects of the Invention) According to the present invention, by forming the first expansion chamber and the second expansion chamber, the expansion chamber is in a negative pressure state at the time of transition to acceleration operation, and the first and second throttle valves are opened. Even if the amount of intake air increases dramatically, this intake air will not fill the expansion chamber and suddenly flow into the combustion chamber, preventing A-bar lean and preventing the occurrence of acceleration displacement. At the time of transition to deceleration operation, the expansion chamber is filled with intake air, and even if the first and second throttle valves are closed and the amount of intake air is drastically reduced, the intake air in the expansion chamber is sucked into the combustion chamber and the wall surface is reduced. This can prevent over-richness caused by suction of adhering fuel.

In addition, by providing the first expansion chamber and the second expansion chamber independently from each other, the intake air in the first and second intake passages does not mix during normal operating conditions, and the expansion chambers are integrated. However, since the intake passages are formed independently, this problem does not occur, and the first and second intake passages handle the operating conditions during acceleration and deceleration, respectively. This makes it possible to obtain good intake characteristics.

(Example) Below, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of a fuel injection type engine, in which two first and second intake ports 3 and 4 open to the combustion chamber 2 of each cylinder of the engine 1, and two first and second intake ports 3 and 4 open to the combustion chamber 2 of each cylinder of the engine 1. Two exhaust ports 5a3 and 6 are open, respectively.

An intake passage 7 for supplying intake air is connected to the intake boats 3 and 4. This intake passage 7 has an air cleaner 8 at its upstream end.1. An intake air amount detection means 9 (air 70-meter) for detecting the amount of intake air is interposed downstream of the air cleaner 8, and an intake passage 7 downstream of this intake air amount detection means 9 is a first intake passage. 7a and second intake passage 7b
It is branched into two parts. The first intake vent M7a is connected to the first intake port 3 of each combustion chamber 2, while the second
The intake passages 7b are connected to the second intake boats 4 of each combustion chamber 2, respectively.

A first throttle valve 10 for controlling the amount of intake air flowing through the first intake passage 7a is provided at the entrance of the first intake passage 7a, and a first throttle valve 10 is provided at the entrance of the second intake passage M7b. M2 intake vent! A second throttle valve 11 is interposed to control the amount of intake air flowing through 87b, and both throttle valves 10.11 are opened and closed in conjunction with throttle operation. The first throttle valve 10 opens when the load is low and becomes fully open as the load increases, and the second throttle valve 11 starts opening when the opening of the first throttle valve 10 reaches the set opening or higher. The M1 intake passage 7a supplies intake air in the entire operating range including the low intake air amount range, and the second intake passage 7b supplies intake air in the high intake ω range.

Further, a first expansion chamber 7G is located downstream of the first throttle valve 10 of the first intake passage 7a, and a second expansion chamber 7G is located downstream of the first throttle valve 10 of the first intake passage 7a.
Second expansion chambers 7d are formed independently of each other downstream of the first and second expansion chambers 7d, and are connected to each cylinder 2 through independent passages from the first and second expansion seedlings 7c and 7d.
is configured.

In the first intake passage 7a, there is a first injection valve 12 that injects fuel in the entire operating range downstream of the first expansion chamber 7C, and in the second intake passage 7b, there is a high intake valve 12 downstream of the second expansion chamber 7d. A second injection valve 13 that injects fuel in a quantity range is provided for each cylinder. This first and second injection valve 12
．． A fuel injection pulse is output to 13 as a fuel control signal from a control unit 14 (microcomputer), and a predetermined amount of fuel is injected according to the width of the injection pulse.

The control unit 1-4 receives an intake air amount signal from the intake air tooth detecting means 9, and also receives an engine speed signal from the rotation speed sensor 15, and detects fuel noise in response to both signals. and timing (number of injections), and outputs a fuel injection pulse having a predetermined pulse width to each injection valve 12 and 13 at a predetermined time.

Further, fuel is supplied to the first and second injection valves 12, 13 by connecting the fuel in the fuel tank 16 from the fuel pump 17 to the first injection valve 12 and the second injection valve 13, respectively, via the filter 18. It is supplied by the lζ fuel supply passage 19, and the injection pressure is adjusted by the pressure regulator 20. This pressure regulator 20 introduces the intake negative pressure in the first expansion chamber 7C of the first intake passage 7a through a negative pressure introduction passage 121, and uses this intake negative pressure to continuously control the flow rate returned from the fuel supply passage 19 to the fuel tank 16. The injection pressure is adjusted to lower the injection pressure when the intake negative pressure is too large. This negative pressure introduction passage 2
1 is the first in which intake air flows and negative intake pressure occurs in the entire operating range.
It is connected to the intake passage 7a side, and preferably introduces the intake negative pressure from a portion near the installation position of the first injection valve 12.

FIG. 2 is a flowchart for explaining the operation of the control unit 14. After the start, in step S1, the fuel injection amount corresponding to the operating state is calculated, and the intake air detected by the intake air carrier detection means 9 is calculated. ωQa,
1 for the engine rotation speed N1 constant determined by the rotation speed sensor 15
Calculate the fuel injection pulse width τ (injection time) from the correction coefficient α, etc.

Note that the correction coefficient α is used to correct for cold times, etc., and the additional correction value τ0 is used to calculate the actual amount of fuel even if the fuel injection pulse is output to the first or second injection valve 12.13. Since it takes a certain amount of time to start injection, this is to correct the rise time. Also, τa
is the basic injection time taking cold correction etc. into consideration, and τb is the acceleration increase time.

Next, the set pulse width τV for starting the fuel injection of the second injector 13 is read out (82), and it is determined whether the injection pulse width τa+τ calculated in step S1 is greater than or equal to the set pulse width τ■.S3 ), when this judgment is NO<low intake air), it is determined whether the asynchronous acceleration switch is on or not (S4), and when the asynchronous acceleration switch is on (YES) in a large acceleration state, asynchronous injection is performed in step S5. While doing so, this asynchronous acceleration switch is turned off (
When NO), the injection pulse τp for the first injection valve 12 and the injection pulse τS for the second injection valve 13 are calculated without performing asynchronous injection (S6).

In the above-mentioned low intake air amount region, the injection pulse τ for the second injection valve 13
S is set to zero, and this 211M O'l valve 1
3, the first injection valve 12 is driven by the control signal of the injection pulse width τp determined in step S1 only by the first injection valve 12, and fuel injection is performed (
S10).

On the other hand, if the determination in step S3 is YES and the intake air amount is in the high intake air amount region, it is similarly determined whether the asynchronous acceleration switch is on (S7), and the asynchronous acceleration switch is on (YES).
When the acceleration state is large, asynchronous injection is performed in step S8, while the asynchronous acceleration switch is turned off (N
In case o), the injection pulse τp for the first injection valve 12 and the injection pulse τS for the second injection valve 13 are calculated without performing an asynchronous operation (S9).
and drives the second injection valve 12.13 to inject fuel
t (810). Note that in this example, the first injection valve 1
The second injection valve 2 and the second injection valve 13 are set to inject the same amount (half each) of fuel.

In the above fuel injection, the outputs of the injection pulses τp and τS when performing asynchronous injection in a high intake air amount region are as shown in FIG.

In the above embodiment, as shown in FIG. 1, the first injector 12 is disposed in the downstream portion of the first intake passage 7a relatively close to the combustion chamber 2, and the first injector 12 injects air. The second injector 13 is located upstream of the first injector 12 so that the fuel is quickly supplied to the combustion chamber 2, thereby improving the responsiveness of the fuel to increases and decreases in the amount of intake air. The injected fuel is disposed in the second intake passage 7b to improve mixing and atomization of the injected fuel and intake air, thereby promoting atomization.

Also, a first
The throttle valve 10 may be provided at the entrance of the first intake passage 7a as shown in FIG. 1, or may be provided in the intake passage 7 upstream of the second throttle valve 11 to obtain the same control effect. .

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an engine intake system according to an embodiment of the present invention, FIG. 2 is a flowchart diagram of a funnel unit, and FIG. 3 is an example of a fuel injection pulse outputted to an injector by FIG. 2. FIG. 1...Engine 2...Combustion chamber 3.4
...Intake port 7...Intake passage 7a.
...First intake passage 7b...Second intake passage 7C...First expansion chamber 7d...Second
Expansion chamber 10...First throttle valve 11...
Second throttle valve 12...First injection valve 13...
・・Second injection valve ■ Fig. 2

Claims (1)

[Claims] (1) A first intake passage that supplies intake air to each cylinder in the entire operating range including the low intake air volume range, a second intake passage that supplies intake air in the high intake air volume range, and a flow through the first intake passage. - a first throttle valve that controls the amount of intake air flowing through the second intake passage; a second throttle valve that controls the amount of intake air that flows through the second intake passage;
In an engine intake system including an injection valve and a second injection valve provided in a second intake passage, a first expansion chamber is provided downstream of the first throttle valve in the first intake passage, and the first expansion chamber is provided downstream of the first throttle valve in the first intake passage. An intake system for an engine, characterized in that a second expansion valve is provided in the second intake passage downstream of the second throttle valve independently of the chamber.