JP3392907B2 - Intake device for 4-cycle internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a four-stroke internal combustion engine, and more particularly, to an intake passage connected to an intake valve opening and a passage area of the intake passage. 4 with throttle valve
The present invention relates to an improvement of an intake device capable of promoting atomization of fuel in a cycle internal combustion engine. 2. Description of the Related Art There has been proposed a four-cycle internal combustion engine having a fuel injection valve for injecting fuel into an intake passage from the viewpoint of improving fuel efficiency. In this type of four-stroke internal combustion engine, the fuel amount is adjusted by controlling the driving time of the fuel injection valve in accordance with the engine load. Since the flow velocity is low, atomization of the fuel is not performed much, and the fuel easily adheres to the wall surface. As a result, a misfire may occur. This tendency is particularly likely to occur during a cold start in which fuel is difficult to atomize. Therefore, in order to form a mixture having an air-fuel ratio that can be ignited even in a low-load region at a spark generating position in the combustion chamber, a larger amount of fuel is taken in so as to be richer than the stoichiometric air-fuel ratio during low-load operation. It is supplied in the passage. [0003] However, the supply of the extra fuel not only reduces the fuel consumption but also emits harmful exhaust gas such as carbon monoxide (CO) and hydrocarbon (HC). Will be. [0004] The present invention has been made in view of the above-mentioned conventional circumstances, and can promote atomization of fuel particularly in a low load region.
It is an object of the present invention to provide an intake device for a four-stroke internal combustion engine capable of reducing exhaust gas pollution and improving fuel efficiency. SUMMARY OF THE INVENTION The present invention comprises an intake passage connected to an intake valve opening and closed by an intake valve, and a throttle valve for controlling a passage area of the intake passage for each cylinder . In the intake device for a four-stroke internal combustion engine, a sub intake passage having a diameter smaller than that of the intake passage is formed between the middle part of the intake passage and the vicinity of the intake valve opening.
And the auxiliary intake passage opening in the middle of the intake passage
Move the piston back and forth according to the opening of the throttle valve in the vicinity
Variable venturibal that opens and closes the above intake passage
And the piston of the variable venturi valve is
Guy consisting of an inclined surface for guiding fuel to the intake passage opening side
And a variable ventilever in the intake passage.
Fuel upstream of the throttle valve and downstream of the throttle valve.
And a fuel injection valve for supplying the fuel.
Directs the injection port to the above-mentioned guide part, and makes the auxiliary intake of the adjacent cylinder
The passages are connected by a balance tube . According to the intake device of the present invention, a sub intake passage having a smaller diameter than the intake passage is provided, and a variable venturi valve for opening and closing the intake passage is provided near the opening of the sub intake passage. In the low load operation range, it is possible to correspond to the opening of the throttle valve.
The variable venturi valve closes, whereby a mixture of air and fuel is introduced from the intake passage into the sub intake passage, and is supplied to the cylinder through the sub intake passage. Since the diameter of the auxiliary intake passage is smaller than that of the intake passage, the flow rate of the air-fuel mixture is increased, and the atomization of fuel can be promoted in the auxiliary intake passage. Further, since the amount of fuel adhering to the wall surface is reduced, it is not necessary to set the air-fuel ratio to an excessively high concentration. The fuel injected from the fuel injection valve is acceptable.
Since it collides with the guide portion of the variable venturi valve, the atomization of fuel can be promoted in the intake passage. The atomized fuel is guided from the guide portion to the sub intake passage opening, and the flow velocity is increased in the sub intake passage to further promote the atomization. As a result, low emission of exhaust gas and improvement of fuel efficiency are achieved. Further, the fuel remaining in the guide section is transferred to the balance pipe.
Is introduced into the auxiliary intake passage for the cylinder in the next intake stroke.
You. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 to FIG.
It is a diagram for explaining the intake device of the cycle engine,
1 is a schematic plan view of a four-stroke engine to which the apparatus of the embodiment is applied, FIG. 2 is a partial cross-sectional side view thereof, FIG. 3 is a longitudinal sectional view of a variable venturi valve of the apparatus of the embodiment, and FIG.
FIG. 4 is a view taken along line IV-IV of FIG. In FIG. 1, reference numeral 1 denotes a water-cooled four-cycle four-cylinder four-valve engine, which comprises a crankcase 2
The cylinder block 3 and the cylinder head 4 are stacked on each other, fastened with head bolts, and a head cover 5 is attached to the upper surface of the cylinder head 4. Four cylinder bores 3a formed in the cylinder block 3
Each of the pistons 7 is slidably inserted therein, and each piston 7 is connected to a crankshaft (not shown) by a connecting rod 8. A combustion recess 4b constituting a combustion chamber is formed on a lower mating surface 4a of the cylinder head 4 on the cylinder block 3 side.
Is recessed. An ignition plug 9 is screwed into the center of the combustion recess 4b, and two intake valve openings 4c and two exhaust valve openings 4d are respectively opened around the ignition plug 9. The openings 4c and 4d are provided in the substantially ring-shaped valve seats 28 and 2 mounted on these portions.
Nine openings are formed respectively. Further, a valve head 10a of the exhaust valve 10 is provided in each exhaust valve opening 4d.
However, the valve head 1 of the intake valve 11 is provided in each intake valve opening 4c.
1a is arranged so as to be able to open and close each opening, that is, to be able to abut against each seat surface of the valve seats 28 and 29. The valve stem 1 of the exhaust and intake valves 10 and 11
Reference numerals 0b and 11b extend obliquely upward in the cylinder axis direction so as to form a predetermined clamping angle when viewed in the cam axis direction, and exhaust and intake lifters 12 and 13 are mounted on upper ends thereof, respectively. Exhaust and intake camshafts 14 and 15 for pressing the lifters 12 and 13 are disposed on the lifters 12 and 13 in a direction perpendicular to the cylinder axis direction and parallel to each other. Each of the exhaust valve openings 4d extends to the front wall 4f side of the cylinder head 4 in the exhaust passage 16, and an exhaust pipe 16b is connected to the wall opening 16a of the exhaust passage 16. Each of the intake valve openings 4c extends to the rear wall 4g side of the cylinder head 4 in the intake passage 17, and an intake pipe 22 is connected to a wall opening 17a of the intake passage 17. An air inlet 2 is provided at an upstream end of the intake pipe 22.
3 is formed, and an air cleaner 24 is connected downstream of the air introduction port 23. A throttle valve 25 for controlling the passage area of the intake pipe 22 is provided downstream of the air cleaner 24. A variable venturi valve (open / close valve) 30 is provided in the middle of the intake pipe 22. As shown in FIG. 2, the variable venturi valve 30 includes a chamber 31 fixed to a top wall of the intake pipe 22 and a chamber 31.
1 and a piston 32 that is slidably provided inside and protrudes into the intake pipe 22. The above-mentioned chamber 31 is formed by the above-mentioned piston 32.
Inside, two compartments 31a and 31b are formed. In the compartment 31a, the piston 32 is connected to the intake pipe 2.
2, a coil spring 33 for urging in the closing direction is contracted. The compartment 31a is provided with a bolt 3 mounted on the upper end opening.
6 is closed. A vertically extending through hole 34 is formed in the piston 32, and the inside of the compartment 31 a and the inside of the intake pipe 22 communicate with each other through the through hole 34. Further, a hole 35 is formed in an upper portion of the intake pipe 22, and the inside of the compartment 31 b and the inside of the intake pipe 22 communicate with each other through the hole 35. The piston 32 on the bottom wall of the intake pipe 22
A sub-intake pipe 40 having a smaller diameter than the intake pipe 22 is connected to a portion opposed to the intake pipe 22. The downstream end opening 40b of the auxiliary intake pipe 40 opens into the intake passage 17 near the intake valve opening 4c. An inclined surface 36 is formed on the upstream side (right side in FIG. 2) of the piston 32.
The lower edge portion 36a of the sub-intake pipe 40 has an upstream end opening 4a.
0a, and has a length (width) substantially the same as the diameter of the opening 40a (see FIG. 3). A single-hole fuel injection valve 45 for injecting fuel into the intake pipe 22 is mounted upstream of the variable venturi valve 30 of the intake pipe 22. The fuel injection valve 45
Is directed to the piston inclined surface 36 of the variable venturi valve 30. As shown in FIG. 3, the injection angle θ of the fuel flow ejected from the ejection hole 45a is set such that the width of the fuel flow tip is slightly larger than the width of the lower edge 36a of the inclined surface 36. Have been. Next, the operation of the above embodiment will be described.
In the low load operation range, the throttle valve 25 is in the fully closed position (the position indicated by the solid line in FIG. 1). Thereby, the intake pipe 22
The flow velocity hardly occurs on the downstream side of the throttle valve in the inside, and a negative pressure state occurs. Since each of the compartments 31a and 31b of the variable venturi valve 30 communicates with the inside of the intake pipe 22 through the holes 34 and 35, the inside of each of the compartments 31a and 31b also has the same negative pressure. Accordingly, the piston 32 is urged downward by the spring force of the coil spring 33 and moves to the fully closed position (solid line position in FIG. 2) or the small opening position for closing the intake pipe 22. In this state, when fuel is injected from the fuel injection valve 45, the fuel advances through the intake pipe 22 and collides with the piston inclined surface 36 of the variable venturi valve 30. Then, the fuel spreads in the form of a thin film on the inclined surface 36, and flows into the auxiliary intake pipe 40 through the upstream end opening 40 a of the auxiliary intake pipe 40 together with the airflow moving downward along the inclined surface 36. Since the diameter of the auxiliary intake pipe 40 is smaller than that of the intake pipe 22, the flow rate of the fuel and air flowing into the auxiliary intake pipe 40 increases in the auxiliary intake pipe 40, whereby the fuel is atomized. While being promoted, adhesion to the wall surface is prevented.
The fuel flows from the downstream end opening 40b of the sub intake pipe 40 into the intake passage 17 near the intake valve opening 28, and flows into the combustion chamber through the intake valve opening 28. Since the wall flow in the intake pipe 22 is prevented in this manner, an air-fuel mixture having an ignitable air-fuel ratio is supplied to the spark generating position in the combustion chamber without supplying extra fuel necessary for supplementing the fuel adhered to the wall. And thereby produce carbon monoxide (CO), hydrocarbon (H
C) and the like, the emission of harmful exhaust gas can be suppressed, and the exhaust gas can be reduced in pollution and fuel efficiency can be improved. It is preferable that the fuel injection start timing in the low load operation range be performed immediately before the intake stroke or during the intake stroke. This is because the atomization of the fuel can be promoted by utilizing the increase in the intake flow velocity. In the medium load operation range, the throttle valve 2
5 is located at the slightly open position (the position indicated by the one-dot chain line in FIG. 1), whereby a flow velocity is generated in the intake pipe 22 downstream of the throttle valve. Variable venturi valve 3 in intake pipe 22
Since the passage area of the mounting portion 0 is narrowed to the bottom wall side by the piston 32, the flow velocity in the intake pipe 22 is larger on the bottom wall side than on the top wall side. Pressure increases. On the other hand, each of the compartments 31a and 31b of the variable venturi valve 30 communicates with the inside of the intake pipe 22 through the holes 34 and 35, respectively, so that the negative pressure in the compartment 31a increases, and The inside of 31b is in a higher pressure state. As a result, the piston 32 moves upward against the spring force of the coil spring 33, and slightly opens the passage in the intake pipe 22 (see the dashed line in FIG. 2). In this state, the piston 3
The downward extension of the second inclined surface 36 is still located in the opening 40 a of the sub intake pipe 40. The fuel injected from the fuel injection valve 45 collides with the piston inclined surface 36 and is atomized and moves downward, and a part of the fuel passes through the upstream end opening 40 a of the sub intake pipe 40 and enters the sub intake pipe 40. The gas flows into the combustion chamber, and the atomization is promoted. The remainder is accelerated by the high-speed airflow passing through the bottom wall of the intake pipe 22 to promote the atomization and atomization, and flows into the combustion chamber from the intake passage 17. Further, in the high load operation range, the throttle valve 25 is set to the fully open position, whereby the flow velocity in the intake pipe 22 further increases, and the negative pressure on the bottom wall (piston-opposed portion) side in the intake pipe 22 is increased. Is higher than other parts. As a result, the piston 32 rises to a fully open position where the lower end surface of the piston inclined surface 36 matches the top wall surface of the intake pipe 22 or the inclined surface 36 slightly projects. As a result, a part of the fuel injected from the fuel injection valve 45 collides with the piston inclined surface 36 and moves downward while being atomized, and most of the injected fuel is stored in the intake pipe 22 similarly to a normal engine. Flows into the combustion chamber from the intake passage 17 while being atomized while flowing at high speed. As described above, in this embodiment, in the low load operation range, the fuel is made to pass through the sub-intake pipe 40 having a smaller diameter than the intake pipe 22, so that atomization of the fuel can be promoted, thereby causing harmfulness. Exhaust gas emission can be suppressed and fuel efficiency can be improved. Further, since the opening and closing of the intake pipe 22 is performed by the variable venturi valve 30 of the piston type, the fuel can be well distributed to the intake pipe 22 and the auxiliary intake pipe 40 according to the engine load. The upstream end opening 40a of the sub intake pipe 40
Is opened to the bottom wall side of the intake pipe 22 and the auxiliary intake pipe 40 is disposed below the intake pipe 22.
The atomized fuel can be reliably introduced into the sub intake pipe 40. Further, in this embodiment, since the auxiliary intake pipes 40 of the adjacent cylinders are connected by the balance pipe 41 (FIG. 1), for example, when fuel for one cylinder adheres and remains on the inclined surface of the piston. Is introduced into the cylinder sub-intake pipe in the next intake stroke, and from this point, the atomization of fuel is further promoted. In the above embodiment, the variable venturi valve 30 is driven by utilizing the negative pressure in the intake pipe 22. However, the application of the present invention is not limited to this. For example, a link mechanism linked to the opening and closing of the throttle valve 25 may be provided, and the variable venturi valve 30 may be driven by the link mechanism. Further, an actuator (for example, a stepping motor) for the piston 32 is provided, and the opening degree of the piston 32 corresponding to the opening degree of the throttle valve 25 is registered in the control unit (ECU) in advance. The actuator may be driven so as to have a desired piston opening. Further, in the above embodiment, the shape of the inclined piston surface 36 of the variable venturi valve 30 is as shown in FIG. 4 , but it may be as shown in FIG . 5 or FIG . 5 and 6 , the same reference numerals as those in FIG. 4 indicate the same or corresponding parts. FIG.
FIG. 3 shows that both side walls 36b are formed in parallel with each other .
5 is different from that shown in FIG. 5 in that no side wall is formed on the inclined surface 36 and the area of the inclined surface is the largest compared to the other two examples. Therefore, although FIG. 5 is superior in atomizing the fuel, the embodiment of FIG. 4 is considered to be the most preferable in consideration of the function of guiding the atomized fuel to the sub intake pipe opening 40a. It should be noted that a fuel injection valve 48 (FIG. 1) may be provided separately from the fuel injection valve 45 as a fuel injection valve dedicated to high load, on the rear wall 4g of the cylinder head 4 so as to inject directly into the intake valve opening. Good. This high-load dedicated fuel injection valve 48
Independent injection is performed at a high load, or the fuel injection valve 45 is operated together with the fuel injection valve 45 described above. Further, since the injection valve 48 is arranged close to the intake valve opening, the injection responsiveness can be improved. Further, the fuel supply means is not limited to the injection valve, and for example, a carburetor may be provided. Furthermore, the injection valve or the carburetor may be common to each cylinder, and may be distributed by a distribution pipe. As described above, according to the intake system for a four-stroke internal combustion engine according to the present invention, it is possible to open and close the sub intake passage having a smaller diameter than the intake passage and the intake passage near the sub intake passage opening.
A variable venturi valve and a variable venturi in the above intake passage
Since the fuel supply means for supplying the fuel upstream of the valve is provided, the atomization of the fuel can be promoted in the sub-intake passage, thereby reducing exhaust gas pollution and improving fuel efficiency. is there. Further, it provided with a guide portion for guiding the fuel to the piston of the variable venturi valve auxiliary air intake passage opening side, since the injection port of the fuel injection valves so as to direct the guide portion, by the guide portion Atomization of fuel can be promoted in the intake passage. Further, the atomized fuel is guided from the guide portion to the auxiliary intake passage opening, so that the atomization can be further promoted in the auxiliary intake passage, thereby reducing exhaust gas pollution and improving fuel efficiency. effective. Furthermore, the fuel remaining in the guide section is
By this, it is introduced into the cylinder auxiliary intake passage of the next intake stroke,
It is atomized here.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a four-stroke engine to which an intake device according to an embodiment of the present invention is applied. FIG. 2 is a partial sectional side view of the engine of the embodiment. FIG. 3 is a longitudinal sectional view (a sectional view taken along line III-III in FIG. 4) of the variable venturi valve of the intake device. 4 is a view taken in the direction of arrows IV-IV in FIG. 3; FIG. 5 is a diagram showing a modification of FIG. 4; FIG. 6 is a diagram showing a modification of FIG. 4; [Description of Signs] 1 Engine 11 Intake valve 17 Intake passage 22 Intake pipe (intake passage) 25 Throttle valve 28 Intake valve opening 30 Variable venturi valve (open / close valve) 36 Inclined surface (guide portion) 40 Sub intake pipe (sub intake passage) ) 40a Secondary intake pipe opening 45 Fuel injection valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02M 69/04 F02M 69/00 320F (56) References JP-A-5-86871 (JP, A) JP, U) Fully open 1988-69771 (JP, U) Fully open 1987-110576 (JP, U) Fully open, 60-107330 (JP, U) Fully open, 60-60944 (JP, U) (58) ) Field surveyed (Int. Cl. ⁷ , DB name) F02M 69/00 F02B 29/08 F02M 23/12 F02M 69/04

Claims (1)

(1) A four-stroke cycle provided with an intake passage connected to an intake valve opening and closed by an intake valve and a throttle valve for controlling a passage area of the intake passage for each cylinder. In the intake device for an internal combustion engine, the intake passage in the middle of the intake passage and the vicinity of the opening of the intake valve are closed.
The sub-intake passage, which is smaller in diameter than the air passage, communicates with the intake passage.
Near the opening of the sub intake passage in the middle part,
The intake passage is moved by moving the piston
A variable venturi valve that opens and closes is provided.
Introduce fuel to the above-mentioned auxiliary intake passage opening side to the revalve piston.
A guide section consisting of an inclined surface for
Upstream of the variable venturi valve in the road and above
Install a fuel injection valve that supplies fuel downstream of the throttle valve
And the injection port of the fuel injection valve is directed to the guide section.
And connect the auxiliary intake passages of adjacent cylinders with each other with a balance pipe.
Intake system of a four-cycle internal combustion engine, characterized in that the binding.