JP3490107B2 - Engine intake control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control device for an engine, and more specifically, a so-called longitudinal vortex (tumble) in which the intake flow rotates in the cylinder axis direction when three intake valves are provided.
The present invention relates to the improvement of the shape of the intake passage and the arrangement position of the intake control valve that can reliably generate the intake air and suppress the decrease of the intake air amount due to the intake resistance.

[0002]

2. Description of the Related Art Conventionally, various so-called lean burn (lean air-fuel ratio combustion) engines have been proposed for the purpose of improving fuel efficiency. In order to stabilize the combustion at a lean air-fuel ratio, it is known that a vertical vortex in which the air-fuel mixture introduced into the combustion chamber rotates in the cylinder axis direction, so-called tumble, is effective.

In order to generate the above-mentioned tumble, an intake control device has been proposed which is provided with an intake control valve that causes the intake air to flow by being biased toward, for example, the top wall side or the bottom wall side of the intake passage (for example, actual opening 61-). No. 132442).

[0004]

By the way, recently, 5
There are cases where three intake valves are provided as in a valve engine. The intake flow introduced from the intake valve opening of the center of this 5-valve engine and the intake flow introduced from the intake valve opening of the side have a difference in the flow rate, the inflow direction, etc. Therefore, the intake control valve described above is simply used. However, although the above tumble can be generated, there is a concern that the intake amount is reduced by the amount that the intake control valve becomes intake resistance.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide an intake control device for an engine that can reliably generate tumble and can suppress a decrease in intake air amount.

[0006]

According to a first aspect of the present invention, a center intake passage for leading a center intake valve opening, which opens into a combustion chamber, to an outer wall of a cylinder head through a bent portion, and a center intake valve opening, open on both sides of the center intake valve opening. In an intake control device for an engine, which comprises left and right side intake passages that lead out two side intake valve openings to the outer wall of a cylinder head through the respective bends, the straight portion length of the side intake passage on the downstream side of the bend is Set the length longer than the length of the straight part on the downstream side of the bent part of the center intake passage, and set the center intake passage to the side intake passage.
The valve block to the upper surface of the cylinder block
On the cylinder block mating surface side of the cylinder head,
Parallel to and near the bent part of the bottom wall of the center intake passage.
Excavate a part of the side and pass below the bottom of the side intake passage
So that only the center intake passage is formed in the valve hole.
An intake control valve that changes the intake passage area according to the intake amount
It is rotatably inserted and arranged, and the intake control valve is made of a round bar.
The valve part formed by removing a part of the round bar is cut out from the center
The intake control valve should be fully opened.
When it is rotated to the position, the valve part will sink into the valve hole and
When rotated to the closed position, the bottom wall side portion of the center intake passage
It is characterized by narrowing down . The invention of claim 2 is
The center intake passage and the side intake passage according to claim 1.
If the main fuel injection valve is installed upstream from the junction with the passage,
On the cylinder block mating side of the above center intake passage
An auxiliary fuel injection valve is provided, and the auxiliary fuel injection valve is in the fully closed position.
Fuel toward the valve section of the intake control valve located at
It is characterized by that. The invention of claim 3 is the same as that of claim 2.
The main fuel injection valve is connected to the left and right side branches.
The feature is that fuel is injected and supplied only to the passage.
The invention of claim 4 is the steady operation according to claim 2 or 3.
When the operating range is low and the intake air amount is low,
Only the injection valve operates, and during normal operation, high intake air volume
Only the above main fuel injection valve can operate
It is characterized by.

[0007]

[Function] When viewed in the cam axis direction, the left and right side intake valve openings are located at a position (closer to the exhaust valve side) closer to the direction perpendicular to the cam axis from the center of the combustion chamber, and the bent portion of the side intake passage is also bent. Since the straight line portion on the downstream side is set longer than the straight line portion of the center intake passage, most of the intake flow from the side intake valve opening passes from the vicinity of the center of the combustion chamber through the exhaust valve side and the cylinder shaft. Inflow with a directional characteristic, so that so-called forward tumble is likely to occur.

On the other hand, the center intake valve opening is located at a position away from the center of the combustion chamber in the direction perpendicular to the cam axis (closer to the side opposite to the exhaust valve) when viewed in the cam axis direction. A part of the intake air flows in from the outer edge of the combustion chamber to generate reverse tumble, and acts to hinder the forward tumble.

Further, since the center intake passage is located at the center of the left and right side intake passages and extends substantially linearly from the external connection opening of the cylinder head outer wall, the intake resistance is higher than that of the left and right side intake passages. Is small, and therefore the intake amount from the center intake valve opening is generally larger than the intake amounts from the left and right intake valve openings. By the way, in the conventional 5-valve engine, the intake amount from the center intake valve opening is about 50% of the total intake amount, and the intake amount from each of the left and right side intake valve openings is about 25% of the total intake amount. is there.

Therefore, in the present invention, only the center intake passage is provided.
By providing an intake control valve having a valve portion located therein, and restricting the bottom wall side of the center intake passage with the intake control valve, the intake flow causing the above-mentioned reverse tumble is suppressed,
Further, regarding the side intake passage, the straight portion on the downstream side of the bent portion is lengthened to further promote the above-mentioned tendency to easily generate the forward tumble, thereby making the occurrence of the forward tumble more reliable.

Further, the center intake passage is located closer to the side intake passage than the side intake passage.
Deviate to the mating surface side of the cylinder block and insert the valve hole
Parallel to the cam shaft on the cylinder head mating side of the head
In addition, a portion of the bottom wall of the center intake passage near the bent portion
Go under the part so that it passes below the bottom of the side intake passage.
Form a round bar in this valve hole, and cut out a part of the round bar
Do not position the removed valve part in the center intake passage.
Since the intake control valve is installed so that it can rotate,
The intake passage area of only the intake passage changes depending on the intake amount.
It As a result, the intake resistance of the side intake passage is reduced as much as possible, the intake amount from the side intake passage is increased, and as a result, the overall intake amount is increased. Although the intake resistance increases and the intake amount decreases in the center intake passage due to the provision of the intake control valve, the center intake passage originally has a large intake amount as described above. The intake amount becomes uniform in the entire combustion chamber, which is rather preferable.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 8 are views for explaining an intake control device for a four-cycle engine according to a first embodiment of the present invention, FIG. 1 is a sectional side view of the engine of the present embodiment, and FIG. FIG. 3 is a schematic plan view of a cylinder head of the engine of the embodiment, FIG. 4 is a bottom view of the cylinder head, and FIGS. 5 and 6 are characteristic diagrams for explaining the formation process of the present invention. 7 is a characteristic diagram showing an injection region, FIG.
Is a flow chart for explaining the operation.

In the figure, reference numeral 1 is a water-cooled 4-cycle in-line 4-cylinder 5-valve engine equipped with the apparatus of this embodiment, which has a crankcase (not shown) having a cylinder block 2 and an upper and lower split cylinder head 3. The structure is such that they are stacked, fastened with head bolts, and a head cover 4 is attached to the cylinder head 3.

A piston 5 is slidably inserted into the cylinder liner 2a of the cylinder block 2, and the piston 5 is connected to a crankshaft (not shown) by a connecting rod 6. Further, four sets of combustion recesses 3a that form a combustion chamber together with the upper surface of the piston 5 are provided on the block-side mating surface of the cylinder head 3 (see FIG. 4).

In each combustion recess 3a, three intake valve openings 7a to 7c and two exhaust valve openings 8a and 8b are formed along the periphery of the combustion recess 3a. As shown in FIG. 4 , the distance from the straight line L connecting the cylinder axes X to the exhaust valve openings 8a and 8b in the direction perpendicular to the cam axis is L1.
And the exhaust valve openings 8a, 8b are connected to the branch passages 8c, 8
The exhaust passage 8 has a bifurcated shape and is led to the front side wall of the cylinder head 3. Further, as shown in FIG. 1, when viewed in the camshaft direction, the exhaust branch passages 8c and 8d overlap each other.

On the other hand, as shown in FIG. 4, the distance from the straight line L to the center intake valve opening 7b is L3, while the distance to the left and right side intake valve openings 7a, 7c is smaller than L3. It is L2. A center branch passage (center intake passage) 7e is formed in the center intake valve opening 7b.
Left and right side branch passages (side intake passages) 7d and 7f are respectively connected to the side intake valve openings 7a and 7c, and these branch passages 7d to 7f are connected to the cylinder head 3 respectively.
The external connection openings 7h on the rear side wall join in a trifurcated shape.

When viewed in the cam axis direction as shown in FIG. 1, the center branch passage 7e is bent near the intake valve opening 7b,
The straight line extends to the external connection opening 7h, and the length of the straight line on the downstream side of the bent portion is only H1 which is substantially equal to the length of the valve seat. On the other hand, left and right side branch passages 7
d and 7f are bent through a straight line portion of H2 longer than the above H1, and extend substantially linearly from here to the external connection port 7h. Further, while the inflow angle formed with the cylinder axis X at the downstream portion (H1 portion) of the bent portion of the center branch passage 7e is θ1,
The inflow angle formed with the cylinder axis X at the downstream portion (H2 portion) of the bent portion of the side branch passages 7d and 7f is larger than θ1 by θ.
It is 2. That is, the inflow angle of the center branch passage 7e is set to be substantially parallel to the cylinder axis X.

Since the positions of the intake valve openings in the direction perpendicular to the cam axis and the inflow angle are set as described above, the center branch passage 7e is located closer to the crankshaft than the side branch passages 7d and 7f (cylinder block mating surface side). ).

The intake valve openings 7a to 7c and the exhaust valve opening 8
a and 8b are intake valves 9a to 9c and exhaust valves 10 and 1, respectively.
The intake valves 9a to 9c and the exhaust valves 10 and 10 are biased in a closing direction by a valve spring 11 and opened by intake and exhaust cam shafts 13 and 14 via a lifter 12. Driven in the direction. When viewed in the cam axis direction, the left and right side intake valve openings 7a and 7c are located closer to the center of the combustion chamber than the center intake valve opening 7b, and the inflow angle θ2 is set to be larger than θ1. The left and right side intake valves 9a, 9c are inclined to the outside with respect to the cylinder axis X more than the center intake valve 9b. Both the center and side intake valve shafts intersect each other at the cam shaft 13 axis.

A valve hole 7g is formed on the block mating surface side of the cylinder head 3 in parallel with the cam shaft. The valve hole 7g is arranged so as to pass through the inside of the branch passage 7e so as to partially engrave the bottom wall portion of the center branch passage 7e, and to pass below the bottom surfaces of both side branch passages 7d and 7f. Here, the inner portion of the bottom wall of the valve hole 7g serves as a recess 7g 'into which a valve portion 18a described later is inserted.

The intake control valve 18 is provided in the valve hole 7g.
Is rotatably inserted and arranged. This intake control valve 18
Is formed by forming a valve portion 18a on a round bar, and the valve portion 18a is located in the center branch passage 7e.
When the intake control valve 18 is rotated to the fully open position, the valve portion 18a is retracted into the recess 7g 'and the center branch passage 7 is inserted.
e is flush with the inner surface of e, and when the intake control valve 18 is rotated to the fully closed position, the bottom wall side portion of the center branch passage 7e is narrowed by about 30 to 70%.

A center branch passage 7e of the intake passage 7 is also provided.
Below, a sub-injector (sub-fuel injection valve) 20 is arranged parallel to the axis of the branch passage 7e. The injection nozzle of the sub-injector 20 is configured to inject fuel toward the valve portion 18a of the intake control valve 18 located at the fully closed position.

An air cleaner (not shown) is connected to the external connection opening 7h of the intake passage 7 via a joint 15. A main injector (main fuel injection valve) 21 is arranged on the top wall of the joint 15 in parallel with the axis of the intake passage 7. This main injector 21 is of a type having three injection nozzles,
Each injection nozzle is directed to each of the branch passages 7d to 7f.

Here, the fuel injection amount from the sub-injector 20 is set so that the air-fuel mixture in the center branch passage 7e is richer than the stoichiometric air-fuel ratio, and the fuel injection amount from the main injector 21 is The air-fuel mixture in each of the branch passages 7d to 7f is set to be leaner than the stoichiometric air-fuel ratio, and is set to be substantially the stoichiometric air-fuel ratio as a whole.

Next, the function and effect of this embodiment will be described. First, the intake control operation in the engine 1 of this embodiment will be described. When the intake air amount is low, such as when the engine rotates at a low speed and the load is low, the intake control valve 18 is rotated to the fully closed position shown in FIGS. 1 and 2, and the bottom wall portion of the center branch passage 7e is narrowed down. As a result, the intake air passing through the center branch passage 7e flows unevenly toward the top wall of the passage, and most of it flows into the cylinder from the center of the combustion chamber into the cylinder as indicated by the solid arrow a in FIG. It is generated and a very small part flows into the cylinder from the outer edge side of the combustion chamber, as indicated by the broken line arrow b in the figure.

In this case, the side branch passages 7d and 7f are also provided.
When the intake air passing through is viewed in the cam axis direction (see FIGS. 1 and 2), the intake valve openings 7a and 7c are located on the combustion chamber center side, and the straight portion H2 on the downstream side of the bent portion is compared. The intake air from the passages 7d and 7f flows in from the center side of the combustion chamber along the top wall of the combustion chamber and in the direction of the cylinder axis (see FIGS. 1 and 2 (b)). A forward tumble is generated (see arrow c).

When the intake air amount is high, such as when the engine is rotating at high speed and under high load, the intake control valve 18 is rotated to its fully open position, and the valve portion 18a is recessed into the recess 7g 'and the inner surface of the center branch passage 7e. The intake air flows into the combustion chamber without resistance.

Next, fuel injection control in the engine 1 of this embodiment will be described with reference to FIGS. 7 and 8. When the fuel injection program is started, engine operating conditions such as engine speed, throttle opening, throttle opening speed, etc. are read, and for example, it is determined from the throttle opening speed whether or not steady operation is being performed (steps S1 and S2). In the case of steady operation, the required intake air amount is map-calculated from the engine speed and the throttle opening, and it is judged from the intake air amount whether or not it is in the low intake air amount operation range (step S3). If so, the required fuel amount is calculated from the steady time map, and only the sub-injector 20 is turned on for a required time at a predetermined timing based on the calculated value (step S4
S5, operating area A in FIG. 7). If it is determined in step S3 that the operating range is not the low intake air amount, it is determined that the operating range is the high intake air amount, the required fuel amount is calculated from the steady time map, and the main injector 21 is calculated based on the calculated value. Only turns on for a required time at a predetermined timing (steps S6, S7, operation area B in FIG. 7).

On the other hand, if it is determined in step S2 that it is not in steady operation, it is determined that it is in transient operation and the process proceeds to step S8 in which it is determined whether or not acceleration is in progress. The required fuel amount is calculated from the map, and both the sub and main ejectors 20, 21 are turned on for a required time at a predetermined timing based on the calculated value. If it is determined in step S8 that the acceleration is not being performed, it is determined that the deceleration is being performed, and the sub and main injectors 20,
Both 21 are turned off and fuel cut is performed (step S11).

As described above, in this embodiment, the intake control valve 18 is provided for the center branch passage 7e which is apt to cause reverse tumble.
The valve portion 18a of (1) prevents intake air from flowing from the outer edge of the combustion chamber (arrow b) and increases the flow from the vicinity of the center of the combustion chamber (arrow a). Further, regarding both side branch passages 7d and 7f where the forward tumble is likely to occur, the straight line portion on the downstream side of the bent portion is lengthened to H2 to promote the forward tumble flow, and the intake control valve which becomes the intake air resistance is eliminated. As a result, forward tumble can be reliably generated when the intake air amount is low, and the required intake air amount can be secured by preventing a decrease in the intake air amount.

5 and 6 show the results of experiments conducted to confirm the effects of strengthening the tumble and preventing the reduction of the intake air amount in this embodiment. In this experiment, each of the branch passages 7d to 7f described above is used.
In which the intake control valve is not provided (STD), and a build-up corresponding to a state where the intake control valve is fully closed is provided on the bottom wall portion of only the center branch passage 7e (center port build-up),
The tumble ratio and the swirl ratio were measured for each of the branch passages 7d to 7f having the above-mentioned build-up on the bottom wall portions (center / side port build-up). Further, in each of the above experimental engines, the intake flow rate was measured while changing the lift amount of the intake valve. Here, the tumble ratio and the swirl ratio mean the vertical rotation speed and the horizontal rotation speed of the intake air per one rotation of the crankshaft.

From FIG. 5, when the buildup corresponding to the intake control valve is provided only in the center branch passage 7e (this embodiment), ST is used.
Compared to D, the tumble ratio is improved to about 6 times. On the other hand, it can be seen that when all the branch passages 7d to 7f are provided with build-up, it is about 1.7 times that of this embodiment. Further, from FIG. 6, it can be seen that the flow rate in the present embodiment is not so much reduced as compared with the STD, but the flow rate is greatly reduced in the case where all the passages are built up. Therefore, in order to suppress the decrease in the flow rate while improving the tumble ratio, it is effective to provide the valve portion 18a only in the center branch passage 7e as in this embodiment.

Further, in this embodiment, when the intake air amount is low during steady operation, the center branch passage 7e is throttled by the intake control valve 18, and the fuel is injected and supplied from the sub-injector 20 only to the passage 7e. Therefore, the rich mixed airflow from the center branch passage 7e and the side branch passages 7d, 7
Since the forward tumbling is generated while forming a layered structure with the air flow from f, and the rich mixed air flow flows into the vicinity of the electrode of the ignition plug 22, it is possible to stabilize the combustion of the lean air-fuel ratio while increasing the air-fuel ratio, The fuel efficiency can be improved.

Further, since both the sub and main injectors 20 and 21 are operated at the time of acceleration, the air-fuel ratio of the entire intake air-fuel mixture can be made the stoichiometric air-fuel ratio, and as a result, the required output can be secured. .

Although the engine having the fuel injection valve has been described in the first embodiment, the present invention introduces the intake air of the engine in which the carburetor is connected to the external connection opening 7h of the intake passage 7 through the cab joint. Of course, it can be applied to the device.

In the first example, the center branch passage 7e
Although the inflow angle θ1 of is smaller than the inflow angle θ2 of the side intake passages 7d and 7f has been described, the present invention can be applied regardless of the inflow angles θ1 and θ2.

9 and 10 show a second embodiment of the present invention, in which the same reference numerals as those in FIGS. 1 to 3 designate the same or corresponding parts. In the present embodiment, the inflow angle θ1 of the center branch passage 7e
Is set to be larger than the inflow angle θ2 of the side branch passages 7d and 7f. That is, the intake air flow from the center branch passage 7e is set so as to flow toward the center of the combustion chamber.

By setting the inflow angles θ1 and θ2 as described above, the upper ends of the center intake valve 9b and the side intake valves 9a and 9c are separated from each other in the direction perpendicular to the cam axis.
Therefore, the center intake valve 9b and the side intake valves 9a and 9c are driven by separate cam shafts. The lengths H1 and H2 of the straight portions on the downstream side of the bent portion are the same as those in the first embodiment.

On the other hand, in this embodiment, the intake control valve 18 is
Rotation is controlled so that the valve portion 18a is located on the upstream side. This is to prevent fuel from accumulating in the control valve portion when the intake control valve 18 is rotated to the fully closed position.

Further, one fuel injection valve 21 is arranged at the upper center of the intake passage 7. This fuel injection valve 21 is on the left,
The fuel is configured to be injected and supplied only to the right side branch passages 7d and 7f (see FIG. 10).

In the device of the second embodiment, the center intake passage 7
Since the inflow angle θ1 of e is set to be large, the intake air flows into the center of the combustion chamber more, and the forward tumble can be generated more reliably. Further, since the air flow flows from the center intake valve opening 7b and the mixture of air and fuel flows into the side intake valve openings 7a and 7c so as to form a layered structure, the layered combustion which is the layered structure opposite to that of the first embodiment is performed. It can be performed.

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

FIG. 11 shows a head surface shape of a piston capable of suppressing the interference between the reverse tumble flow and the forward tumble flow. This is an example in which a ridge-shaped convex portion 5a is formed on the top surface of the piston 5 for allowing the intake flow from the side intake passage and the center intake passage to flow independently. In this example, the mutual interference of the three flows can be suppressed, and the tumble can be surely generated accordingly.

[0049]

As described above, according to the intake control system for an engine of the present invention, the intake flow causing the reverse tumble is suppressed by narrowing down the bottom wall side of the center intake passage with the intake control valve. By increasing the length of the straight portion on the downstream side of the bent portion of the side intake passage, the tendency to generate forward tumble is further promoted, so that there is an effect that the forward tumble can be generated more reliably. Since it is provided only in the side intake passage and not provided in the side intake passage, the intake resistance of the side intake passage is reduced as much as possible, so that there is an effect that the total intake amount can be increased. Further, in the present invention, the center intake
The passage is biased toward the cylinder block mating side from the side intake passage.
The valve hole near the bend of the bottom wall of the center intake passage.
Part of the bottom of the intake passage below the bottom of the left and right side intake passages
It is formed so that it passes through and is made of a round bar, and the valve part is the center intake
The intake control valve formed to be located in the passage portion is
Since it is inserted and arranged in the valve hole, the above-mentioned effects can be achieved with a simple structure.
The result can be realized.

[Brief description of drawings]

FIG. 1 is a sectional side view of an engine including an intake control device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a function and effect of the first embodiment device.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a bottom view of a cylinder head of the engine of the first embodiment.

FIG. 5 is a characteristic diagram showing experimental results for confirming the effect of the first embodiment device.

FIG. 6 is a characteristic diagram showing experimental results for confirming the effects of the device of the first embodiment.

FIG. 7 is a characteristic diagram showing a fuel injection region of the first embodiment device.

FIG. 8 is a flow chart diagram for explaining the operation of the apparatus of the first embodiment.

FIG. 9 is a sectional side view of an engine equipped with a second embodiment device of the present invention.

FIG. 10 is a sectional plan view of the engine of the second embodiment.

FIG. 11 is a diagram showing changes in the shape of the piston top surface in each of the above embodiments .
It is a perspective view showing a form example.

Front page continuation (72) Inventor Tomotaka Takano 2500 Shinshinkai, Iwata, Shizuoka Prefecture Yamaha Motor Co., Ltd. (56) References JP-A-3-264729 (JP, A) JP-A-3-160113 (JP, A) ) Actual Kai 3-99834 (JP, U) Actual Kai 1-173421 (JP, U) Actual Sho 63-174537 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02B 31/02 F02M 69/00 F02M 69/00 360

Claims (4)

(57) [Claims] 1. A center intake passage that leads out a center intake valve opening that opens into a combustion chamber to an outer wall of a cylinder head through a bent portion, and two side intake valve openings that open on both sides of the center intake valve opening. In an intake control device for an engine having left and right side intake passages led out to the outer wall of the cylinder head, the straight portion length of the side intake passage on the downstream side of the bent portion is set to the straight portion length of the center intake passage on the downstream side of the bent portion. Longer than that, and center intake
The passage is biased toward the cylinder block mating side from the side intake passage.
The cylinder block of the cylinder head above.
Parallel to the camshaft on the mating surface side and the bottom of the center intake passage
Part of the wall near the above-mentioned bent part
It is formed so that it passes below the bottom surface, and the valve hole
The intake passage area of only the intake passage is changed according to the intake amount.
The intake control valve to be inserted is rotatably inserted, and the intake control is performed.
The valve is made of a round bar, and a part of the round bar is notched and removed.
Part is located in the center intake passage, and
When the intake control valve is rotated to the fully open position, the valve section
When the valve is immersed in the valve hole and rotated to the fully closed position, the center suction
An intake device for an engine, characterized in that a bottom wall portion of an air passage is narrowed down . 2. The center intake passage according to claim 1,
The main fuel injection valve upstream from the confluence of the side intake passage with the
And the cylinder block of the center intake passage
An auxiliary fuel injection valve is provided on the lock face side, and the auxiliary fuel injection valve
Toward the valve section of the intake control valve located in the fully closed position
An engine intake device characterized by injecting fuel. 3. The main fuel injection valve according to claim 2,
Supplies fuel only to the above left and right side branch passages
An air intake device for an engine characterized by: 4. The steady-state operation according to claim 2 or 3,
And when the intake air amount is in the low operating range
Only the valve operates, in normal operation and high intake air amount operation range
If it is, only the main fuel injection valve should operate.
Characteristic engine intake device.