JPS6365117A - Air intake device for engine - Google Patents

Abstract

PURPOSE:To form an air-fuel mixture in a layer properly in a combustion chamber and ensure proper laminar combustion by providing an air supply means for supplying air to the neighborhood of an air intake valve and a control device for controlling air supply timing. CONSTITUTION:The neighborhood of an air intake valve 18 is provided with an air supply pipe 17 as an air supply means and a control unit 22 for so controlling air supply timing as to start at a stage predetermined earlier than the opening of the air intake valve 18 and finish in the early half of an air intake stroke. According to the aforesaid constitution, air is supplied to the neighborhood of the air intake valve 18 at a stage predetermined earlier than the opening of said valve 18,thereby removing an air-fuel mixture stagnating in the neighborhood thereof. And the air so supplied is fed to a fuel combustion chamber from the time of opening the air intake valve 18 to the first half of the air intake stroke and the air-fuel mixture is supplied in the latter half of the air intake stroke. According to the aforesaid constitution, an air-fuel mixture in a layer form is properly made in the fuel combustion chamber and laminar combustion can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine intake system, and in particular to an engine intake system that is equipped with a fuel supply means for supplying fuel upstream of a throttle valve to perform single-state combustion. Regarding.

(Prior Art) Conventionally, as an intake system for an engine that performs stratified combustion in a combustion chamber, for example, as disclosed in Japanese Patent Application Laid-Open No. 56-81217, there has been an intake system that supplies a rich air-fuel mixture or connects an intake passage. The main intake (I\) near the intake valve opens to the
An 01 intake valve that opens and closes the sub-intake passage is provided, and when the sub-intake valve is opened, the rich mixture supplied from the fD1 intake passage is placed in the upper layer and the lean mixture supplied from the main intake passage is placed in the lower layer. It is known that a stratified air-fuel mixture is formed within the combustion chamber to improve combustibility.

(Problem to be Solved by the Invention) However, when such an intake device is installed in an engine that is equipped with a carburetor that supplies fuel to the throttle valve-hi flow by 1 m, the air-fuel ratio set in the main intake passage and the 01 intake passage is Since different carburetors must be arranged, the intake system becomes complicated.

Therefore, a carburetor is placed only in the main intake passage, and air is supplied to the 01 intake passage, and at the same time as the intake valve is opened, the sub-intake valve is activated and combustion occurs from the sub-intake passage! By supplying air into the combustion chamber, then closing the auxiliary intake valve and supplying the air-fuel mixture from the main intake passage into the combustion chamber, a mixture table and an air table form vertically in the combustion chamber. It is conceivable to simplify the intake device.

However, in this case, since the intake passage opens into the main intake passage upstream of the intake valve, the air-fuel mixture that remained between the frontage of the 01 intake passage and the intake valve at the beginning of the intake stroke is combusted. There is a problem in that it is inhaled into the chamber, making it impossible to achieve good stratification.

The present invention has been made in view of these points, and its purpose is to achieve good stratification within the combustion chamber by supplying air to the main intake passage at an appropriate timing. be.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is directed to an engine intake system that includes a fuel supply means 1411 that supplies fuel upstream of a throttle valve. Then, the air supply means that supplies air to the vicinity of the intake valve and the timing of air supply from the air supply means are υ controlled so as to start from a predetermined time earlier than the intake valve opening timing and end in the first half of the intake stroke. The configuration is provided with a control means for controlling.

(Function) With the above configuration, in the present invention, air is supplied to the vicinity of the intake valve by the air supply means from a predetermined time earlier than the intake valve opening timing, and the air-fuel mixture remaining in the vicinity of the intake valve is removed by this air. be done.

Next, the intake air? opens and the air is supplied into the combustion chamber, and the supply of this air ends in the first half of the intake stroke. When this air supply ends, the air-fuel mixture generated by the fuel supply means at the beginning of the intake stroke is supplied into the combustion chamber, and the air-fuel mixture and the -a layer are formed vertically in the combustion chamber.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an engine equipped with an intake system according to an embodiment of the present invention. In the figure, 1 is the first . 3rd, 4th. Second
A 4-cycle inline 4-cylinder engine that explodes in the order of the cylinders, 2
One end opens to the atmosphere via the 1acrina 3, and the other end opens to each combustion chamber 1a of the engine 1 to supply air (intake) to the engine 1.
A main intake passage 4 that supplies air) has one end opening into each combustion chamber 1a of the engine 1 and the other end opening to the atmosphere.
This is an exhaust passage for discharging exhaust gas from the

Further, the main intake passage 2 is provided with a throttle valve 5 for adjusting the intake flow rate, and upstream of the throttle valve 5 is a carburetor 6 serving as a fuel supply means for supplying fuel to the main intake passage 2.
is installed. The carburetor 6 is connected to a fuel tank 8 via a fuel supply means 7, and the fuel supply passage 7
A fuel pump 9 is interposed therein. Further, a charging device 10 for charging the fuel is interposed in the fuel supply passage 7 downstream of the fuel pump 9, and a bypass passage 11 for bypassing the charging device 10 is provided, and an upstream branch of this bypass passage 11 is provided. A fuel passage switching valve 12 is provided in the section. Note that 13 is a return passage for returning the fuel in the fuel supply passage 7 to the fuel tank 8, and 14 is a return valve provided in the return passage 13.

Further, an ultrasonic vibration type 7 tomizer 15 is disposed in the venturi of the vaporization@6.

Further, an air supply 17 has one end opening into the air cleaner 3 and the other end opening upstream of the intake valve 18 disposed at the downstream end of the main intake passage, and supplies air to one area near the intake valve 18. An air supply pipe as a means, the air supply pipe 1
One air valve for opening and closing the air supply pipe 17 is interposed in the air supply pipe 7 .

In addition, 20 is a catalyst device installed in the exhaust passage 4 for converting exhaust gas into 7, and 21 is a distributor.

The air valve 19, the charging device 10. The operation of the alumizer 15, fuel passage switching valve 12, fuel pump 9, and return valve 14 is controlled by a control unit 22. The control unit h22 includes an air cleaner 3.
An intake air temperature sensor 23 is placed in the
and a negative pressure sensor 24 which is arranged downstream of the throttle valve 5 in the main intake passage 2 and detects the engine load based on the intake negative pressure.
A water temperature sensor 25 that detects the temperature of engine cooling water, an air-fuel ratio sensor 2G that is arranged upstream of the catalyst device 20 in the exhaust passage and 4 and detects the air-fuel ratio of the engine based on oxygen 11 components in the exhaust gas, cylinder identification, and crank angle. Each signal is inputted to the distributor 21 which detects.

Next, the operation of the control unit 22 is explained in FIG.
This will be explained based on the flowchart shown in FIG. In FIG. 2, first, in step S1, signals are input from the intake temperature sensor 23, pressure sensor 24, water temperature sensor 25, and air-fuel ratio sensor 26 to sample the operating conditions, and based on these, in step S2, the engine load is set to low. If it is YES, which means it is in the A region shown in Fig. 6 and the load is low, then in the next step S (it is determined whether the engine cooling water temperature is higher than the set temperature α). .

When the engine cooling water temperature is higher than α (YES), it is determined that it is a warm time, and timed air operation is executed in step S4 to perform stratified combustion, and air is supplied from the air supply means (air supply pipe 17). The supply timing of i! is controlled to start from a predetermined period earlier than the intake valve opening timing and end in the first half of the intake stroke, and by this step S4, i! ,
It constitutes the control means 27. Furthermore, in step $5, the fuel is switched to the rm path switching valve 12' to the electric device side, and the charging device 10 and the atomizer 15 are not operated.

In the above-mentioned timed door operation, first, the engine speed and zero intake pressure are read in step S2+, without going to the timing-interrupted routine shown in FIG.
2, the opening timing Δθ1 of the air valve 19 relative to the engine speed and intake negative pressure (engine load), that is, the crank angle (from the exhaust stroke start time which is the reference crank angle) until the air valve 19 opens (from the exhaust period) The '1st map in which the number of angles included) is read, and in step 823, Δθ1 that matches the engine speed and intake negative pressure is selected.Furthermore, in step S24, the engine speed and intake zero pressure (
Opening of air valve 19 in response to engine load)? ! ! I1
The second map in which the interval Δθ2 is set is read, and step S2
5, select Δθ2 that matches the engine speed and intake negative pressure.

Furthermore, the process proceeds to the engine rotational speed signal interwoven routine shown in FIG. 4, and in step S31, the l-a-valve valve timing Δθ1 and the air valve opening period Δθ2 are read, and the next step S32
Each time the crank angle advances by 301, 1 is added to the counter C. This counter C is generated in the tG signal interwoven routine shown in FIG. 5, and is cleared every time the crankshaft rotates twice and the intake stroke of the first cylinder starts.

Next, in step S33, it is determined whether the counter C has reached (6+Δθ1). When YES is C-6 + Δθ1, as shown in Fig. 7, the reference crank angle of the fourth cylinder has been advanced by Δ01, and the predetermined timing (exhaust period - 80I) is earlier than the intake valve opening timing. judge,
In step S34, the air valve 19 of the fourth cylinder is opened. At this time, the intake valve 18 is not listening yet, and the air-fuel mixture accumulated near the intake valve 18 is removed by air from the air supply pipe 17.

Furthermore, when the intake valve 18 opens, air from the air supply pipe 17 is supplied into the combustion chamber 1a. In this case, since the air-fuel mixture near the intake valve has been removed in advance, air without any air-fuel mixture is drawn into the combustion chamber 1a.

Next, in step 835, the counter C is set to (6+Δθi+
Δθ2). And C=6+
ΔOI+Δθ2, Y[If ES, the reference crank angle f) of the fourth cylinder has progressed by (Δθ1→−Δθ2), and it is determined that the engine is in the first half of the intake stroke, and in step 836, the air valve 19 of the fourth cylinder is closed. As a result, in the second half of the intake stroke, the air-fuel mixture generated by the carburetor G is supplied into the combustion chamber 1a, and the air-fuel mixture and air are spaced vertically in the combustion chamber 1a.
It is formed into a shape, resulting in stratified combustion. In this case, the vaporization and atomization of the fuel in the vaporizer 6 is promoted by the operation of the belt clearing device i10 and the atomizer 15.

Further, in steps 337 to SAo, the second cylinder is activated, and in steps 841 to S44, the first cylinder is activated, and in steps 845 to S, the first cylinder is activated.
In B, for the third cylinder, the air valve 1 is activated at the time when Δθ1 advances from the reference crank angle, as in the case of the fourth cylinder above.
9 is opened, and one air valve is closed at a timing further advanced by Δθ2 to generate a stratified mixture in each cylinder, resulting in stratified combustion.

On the other hand, if the water temperature is smaller than α in step S3 of FIG.
When it is determined that the temperature is o, the timed air operation is stopped in step Sc and the charging device 10 and the atomizer 15 are activated in step S5 in order to promote warm-up for the cold time.
This aims to promote vaporization and atomization of the fuel in the vaporizer 6.

In addition, when it is determined that the load is not low in step Sz of Fig. 2, the engine output should be increased (the next step S
7 to stop the timed air operation and atomizer 1
5 is disabled. By stopping this timed air operation, the air supply from the air supply pipe 17 is stopped, the air-fuel ratio becomes rich with good responsiveness, and the engine output is quickly increased.

Furthermore, in step $8, it is determined whether the engine load is 1!5 inches. If YES is found in region C shown in FIG. 6 and the load is high, the charging device 10 is deactivated in step S9, and the promotion of vaporization and atomization of the fuel in the carburetor 6 is stopped. This prevents the vaporized fuel from expanding and ensures the amount of intake air to be filled, and also prevents an increase in power consumption due to an increase in fuel temperature 'R'. Meanwhile, step 88″
When it is determined to be cNO, is it a medium load? Then, in step S10, the charging device 10 is activated.

Regarding the control of the air-fuel ratio, when the water temperature is around the set temperature α, the target air-fuel ratio is set to the stoichiometric air-fuel ratio.

In addition, when the water temperature is lower than the set temperature intake α, the air-fuel ratio is gradually shifted to the target air-fuel ratio on the rich side by increasing the number of joggers, while when the water temperature is higher than the set temperature intake α, the air-fuel ratio is gradually shifted to the target air-fuel ratio on the rich side. The air-fuel ratio is gradually increased to gradually shift to the target air-fuel ratio on the lean side.

(Effects of the Invention) As explained above, according to the engine intake and arrangement of the present invention, air is supplied to the vicinity of the intake valve from a predetermined time XII earlier than the intake valve quantity valve timing. By removing the stagnant air-fuel mixture and supplying this air into the combustion chamber from the time between the intake valves to the first half of the intake stroke, the air-fuel mixture is supplied into the combustion chamber in the second half of the intake stroke, thereby ensuring that the air-fuel mixture is stratified within the combustion chamber. It is possible to form an air-fuel mixture to achieve good combustion.

Live drawing IL'! The most explanatory drawings show an embodiment of the present invention, and FIG. 1 is a general schematic diagram, FIGS. 2 to 5 are flowcharts explaining the operation of the control unit, and FIG. 7 is an explanatory diagram showing the opening/closing timing of the air valve.

5... Throttle valve, 6... Carburizer, 17... Air supply tlOffi, 18... Intake valve, 27... Control means.

・、i-edict- Figure 3 Figure 4

Claims (1)

[Claims] (1) In an engine intake system equipped with a fuel supply means for supplying fuel upstream of a throttle valve, the air supply means supplies air near the intake valve, and the air supply timing from the air supply means is adjusted to the intake valve. An intake system for an engine, characterized in that it is provided with a control means for controlling the intake stroke to start from a predetermined time earlier than the valve opening timing and to end in the first half of the intake stroke.