JP2000320434A - Engine with multiple intake valves - Google Patents

Abstract

(57) [Problem] To provide an engine having a plurality of intake valves capable of stabilizing combustion and reducing costs. A plurality of intake ports (5) opening to a combustion chamber (C).
a, 5b, a plurality of intake valves 6a, 6b for opening and closing these intake ports 5a, 5b, and each intake port 5a, 5b.
Independent intake passages 3a, 3b connected to
And a fuel injector 13 for injecting fuel into only one of the plurality of intake passages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine having a plurality of intake valves and a single or a plurality of fuel injectors per cylinder.

[0002]

2. Description of the Related Art An engine equipped with a conventional fuel injector is:
A fuel injector that injects fuel into an intake passage to which air is supplied from an air cleaner is provided. The fuel injector
The fuel injection port is closed with a plunger, and the plunger is sucked and moved by energizing an electromagnetic coil by an injection control device to inject pressurized fuel, a fuel injection valve, an injector, or Also called a fuel injection device.

In an engine having a plurality of intake valves per cylinder, in many cases, one intake passage branches midway into the number of intake valves. Irrespective of the shape of the branch point, the intake air is disturbed regardless of the shape. Therefore, differences in the distance from the intake valve to the position of the branch point cause differences in engine performance and characteristics. Therefore, it is difficult to set the position and shape of the branch point.

In the case of using a fuel injector, a fuel injector is provided upstream of the branch point, and the fuel injector is divided from the fuel injection port toward each of the branched passages so that fuel is injected. It is necessary to devise the shape. in this case,
Unless the fuel injector is an expensive dedicated product, fuel cannot be directed only to the center of the branch passage, so fuel easily adheres to the wall surface, and the fuel adhered to this wall surface may be atomized with a delay, If the fuel adhering to the air enters the combustion chamber with a delay along the wall surface, it may deviate from the intended air-fuel ratio.

On the other hand, an engine in which a fuel injector is provided at a position sufficiently upstream from a branch point of an intake passage (Japanese Patent Laid-Open No.
In the case of -280444), a dedicated fuel injector is not required, but the distance from the fuel injector to the intake port is long, so that the amount of fuel attached to the wall surface increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems. By using a general-purpose fuel injector, the cost can be reduced and a predetermined air-fuel ratio can be obtained. It is another object of the present invention to provide an engine having a plurality of intake valves capable of stabilizing combustion.

[0007]

In order to achieve the above object, an engine according to one aspect of the present invention comprises a plurality of intake ports opening to a combustion chamber, a plurality of intake valves opening and closing these intake ports, The fuel cell system includes a plurality of independent intake passages connected to each intake port, and a fuel injector that injects fuel into only one of the plurality of intake passages.

According to the above configuration, since fuel is injected into only one intake passage, there is a difference in density from the intake air from other intake passages. For this reason, the turbulence of the mixture flow in the combustion chamber increases, and the combustion speed can be increased. In addition, as a fuel injector, a general-purpose type that injects fuel into a single conical region in an intake passage that is not branched can be used, so that cost reduction is realized and the fuel is directed to the center of the passage. Thus, the adhesion of fuel to the wall surface can be suppressed.
Further, since a plurality of independent intake passages are formed in the cylinder head, the diameter of each intake passage can be reduced as compared with a configuration in which a branched intake passage is formed. For this reason, the throttle body to which the fuel injector is attached also has a small diameter, so by avoiding interference with the cylinder head, the throttle body is moved closer to the intake port to reduce the length of the intake passage from the fuel injector to the intake port. Since the length can be shortened, the amount of fuel adhering to the wall surface of the intake passage can be further reduced. For this reason, the amount of fuel that enters the combustion chamber with a delay is reduced, and a predetermined air-fuel ratio is obtained, and combustion is stabilized.

According to another aspect of the present invention, there is provided an engine having a plurality of intake ports opened to a combustion chamber, a plurality of intake valves for opening and closing these intake ports, and a plurality of independent intake ports connected to each intake port. The fuel cell system includes a passage and a fuel injector that injects fuel into each intake passage, and a distance from the fuel injector to an intake port is set to be different for each intake passage.

According to the above configuration, since the distance from the fuel injector to the intake port differs for each intake passage, a difference in the flow velocity of the intake air and a difference in temperature (density difference) occur. Turbulence increases and combustion speed increases. Further, when a difference is provided between the fuel injection amounts of the plurality of fuel injectors, the difference in the density of the intake air increases, and the combustion speed further increases.

In a preferred embodiment of the present invention, a fuel injector is provided only in one intake passage, and a plurality of fuel injectors are arranged at an upstream side and a downstream side of the intake passage. According to this configuration, since the intake air temperature is reduced by the heat of vaporization of the fuel injected from the fuel injector on the upstream side, the charging efficiency is increased and the engine output is improved. In addition, one fuel injector has injection characteristics suitable for low rotation and low load, and the other fuel injector has injection characteristics suitable for high rotation and high load. Performance (fuel, output, etc.) can be exhibited.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view showing a first embodiment of the present invention. A cylinder head 2 is mounted on a cylinder 1 on which a piston (not shown) slides in a bore. , A downstream portion of a pair of intake passages 3a and 3b for introducing intake air into a combustion chamber C (FIG. 2) formed by the cylinder 1 and the cylinder head 2, and a pair of branched upstream portions 4a and 4b of the exhaust passage 4. Are formed. The cylinder head 2 has a pair of intake passages 3.
A pair of intake ports 5a and 5b whose downstream portions a and 3b open to the combustion chamber C and exhaust ports 7a and 7b whose upstream portions of the branch exhaust passages 4a and 4b open to the combustion chamber C are formed.
Further, as shown in FIG. 2, intake valves 6a and 6b for opening and closing intake ports 5a and 5b, and exhaust ports 7a and 7b.
And exhaust valves 8a and 8b that open and close the air.
21 and 22 are valve seats.

FIG. 1 shows a throttle body 9 having one end (downstream end) attached to the cylinder head 2 with bolts 10a and 10b to form a part of the intake passages 3a and 3b. 9 a pair of intake passages 3
a and 3b respectively include throttle valves 11a and 11b.
b is provided. An air cleaner 14 is connected to the other end (upstream end) of the throttle body 9. The upstream ends of the intake passages 3 a and 3 b are inserted into openings 14 a provided downstream of the elements of the air cleaner 14. I have. Further, as shown in FIG. 2, a fuel injection passage 12 is formed through an outer wall of one intake passage 3a of the throttle body 9, and a fuel injector 13 is disposed outside the fuel injection passage 12. The fuel injected from the injection port formed at the tip of the fuel injector 13 is injected into the intake passage 3a through the fuel injection passage 12.

According to the above configuration, since fuel is injected only into one intake passage 3a shown in FIG. 1, there is a difference in density from the intake air from the other intake passage 3b. For this reason, when the intake valves 6a and 6b are opened, the turbulence of the air-fuel mixture in the combustion chamber C increases, and the combustion speed increases.

Further, since the fuel injector 13 can be of a general type for injecting fuel into a single conical region in the intake passage 3a which is not branched, cost reduction can be realized and fuel can be passed through the passage. By directing the fuel toward the center, the adhesion of fuel to the wall surface can be suppressed. Further, since two independent intake passages 3a and 3b are formed in the cylinder head 2, the diameter of each intake passage 3a and 3b can be made smaller than in the case where a branched intake passage is formed. Therefore, the outer diameter of the throttle body 9 is also reduced, so that the throttle body 9 can be brought close to the intake port 5a while avoiding interference with the cylinder head 2, whereby the throttle body 9 in the intake passage 3a can be moved from the throttle body 9 to the intake port 5a.
, The amount of fuel adhering to the wall surface of the intake passage 3a can be reduced. For this reason, the amount of fuel adhering to the wall surface and entering the combustion chamber C with a delay is reduced, a predetermined air-fuel ratio is obtained, and combustion is stabilized.

FIG. 3 is a view showing a cylinder head of another arrangement example of the fuel injector in the first embodiment. In this arrangement example, without providing the throttle body 9 (FIG. 2),
The fuel injection passage 12 is formed in the wall of the intake passage 3a of the cylinder head 2, and the vicinity of the valve portion of the intake valve 6a passes through the fuel injection passage 12 from the fuel injector 13 disposed outside the cylinder head 2. This is a configuration in which fuel is injected toward. Accordingly, the distance L from the fuel injector 13 to the intake port 5a, that is, the distance along the intake passage 3a from the center position of the opening of the fuel injection passage 12 to the intake passage 3a to the intake port 5a is reduced.

According to the above configuration, the fuel collides with the valve portion of the intake valve 6a having a high temperature to promote vaporization, and the amount of fuel adhering to the wall surface of the intake passage 3a is further reduced, so that the combustion chamber C , The amount of fuel that enters later is further reduced, a predetermined air-fuel ratio is obtained, and combustion can be stabilized.

FIG. 4 is a schematic plan view showing a second embodiment of the present invention. This embodiment includes a second fuel injector 15 disposed in the other intake passage 3b in addition to a first fuel injector 13 that injects fuel into one intake passage 3a. The distance from the second fuel injector 15 to the intake port 5b is longer than the distance L1 from the fuel injector 13 to the intake port 5a.
The distance L2 is set larger.

Further, of the two fuel injectors 13 and 15, the fuel injection amount (the fuel supply amount per unit air flow) from the second fuel injector 15 having the long distance L2 is the distance L1.
Is set to be larger than the fuel injection amount from the short fuel injector 13.

According to the second embodiment, the distance L2 from the second fuel injector 15 to the intake port 5b is longer than the distance L1 from the fuel injector 13 to the intake port 5a. Is longer in air-fuel mixture than air at the intake port 5a and flows over a longer distance, so the frictional resistance received from the wall surface becomes larger, the flow velocity becomes slower, and the fuel is cooled by heat of vaporization. The longer the period, the lower the temperature and the higher the density. Due to the difference between the intake air flow velocity and the difference between the intake air densities, the turbulence of the air flow in the combustion chamber C increases, and the combustion velocity increases.

FIG. 5 is a schematic plan view showing a third embodiment of the present invention. In the third embodiment, one intake passage 3
a first fuel injector 13 for injecting fuel into the first fuel injector 13 and a second fuel injector 15 for injecting fuel into the intake passage 3a upstream of the first fuel injector 13 are located downstream and upstream. Are placed away. In the cylinder head 2, an intake passage 3a,
3b is connected to the bolts 10a, 1
The throttle body 9 which forms part of the intake passages 3a and 3b is attached to the connecting member 24.

As shown in FIG. 6, the first fuel injector 13
Is a fuel injection passage 12 formed in the throttle body 9.
The fuel is injected into the intake passage 3a through the passage. On the other hand, the second
The fuel injector 15 opposes the upstream end opening of the intake passage 3a and injects fuel from this opening in the direction of the central axis in the intake passage 3a. The first fuel injector 13 and the second fuel injector 15 are supplied with fuel from a common fuel supply hole 16 provided in a connecting pipe 27 connecting them.

The first fuel injector 13 mainly operates at a low speed.
The second fuel injector 15 has fuel supply characteristics suitable for low load and performs fuel injection over the entire range from idling to high speed rotation, whereas the second fuel injector 15 has fuel supply characteristics suitable for high speed and high load. Is controlled so as to inject fuel over a medium to high speed rotation range and to compensate for the shortage of the injection amount of the first fuel injector 13.

According to the third embodiment, similarly to the second embodiment, the fuel injector having the characteristics suitable for the idling to medium speed rotation range and the fuel injection characteristics suitable for the middle to high speed rotation range are provided. With the use of a rotating device, suitable rotation characteristics can be obtained over the entire rotation range from idling to a high-speed rotation range.

Further, since the fuel is injected only into one of the intake passages, the temperature difference (density difference) from the intake air from the other intake passage becomes large. Therefore, the turbulence of the air-fuel mixture in the combustion chamber increases, and the combustion speed increases.

[0026]

According to one aspect of the present invention, since fuel is injected into only one intake passage, a temperature difference (density difference) occurs between the intake air from the other intake passage and the intake air. For this reason, the turbulence of the mixture flow in the combustion chamber increases, and the combustion speed increases. In addition, the fuel injector can use a general-purpose type that injects fuel in a single conical area into the intake passage that is not branched, so that cost reduction is realized and fuel is directed to the center of the passage. Thus, the adhesion of fuel to the wall surface can be suppressed. Further, since a plurality of independent intake passages are formed in the cylinder head, the diameter of each intake passage can be reduced. Therefore, the length of the intake passage can be shortened by bringing the throttle body, to which the fuel injector is attached, closer to the intake port while avoiding interference with the cylinder head, thereby reducing the amount of fuel adhering to the wall of the intake passage. Can be. For this reason, the amount of fuel that enters the combustion chamber late is reduced,
A predetermined air-fuel ratio is obtained, and combustion is stabilized. Further, since a standard type having a single conical expansion can be used as the fuel injector, cost can be reduced.

According to another configuration of the present invention, a fuel injector for injecting fuel into each independent intake passage is provided, and the distance from the fuel injector to the intake port is set to be different for each intake passage. In addition, a difference occurs in the flow velocity and density of the intake air for each intake passage, so that the turbulence of the mixture flow in the combustion chamber increases and the combustion speed increases. Further, when a difference is provided between the fuel injection amounts of the plurality of fuel injectors, the difference in the density of the intake air increases, and the combustion speed further increases.

[Brief description of the drawings]

FIG. 1A is a schematic plan view showing a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a longitudinal sectional view showing the cylinder head of the first embodiment.

FIG. 3 is a longitudinal sectional view showing a modification of the cylinder head of the first embodiment.

FIG. 4 is a schematic plan view showing a second embodiment of the present invention.

FIG. 5 is a schematic plan view showing a third embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing a cylinder head according to a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... cylinder, 2 ... cylinder head, 3a, 3b ... intake passage, 4 ... exhaust passage, 5a, 5b ... intake port, 6a,
6b: intake valve, 7a, 7b: exhaust port, 8a, 8
b: exhaust valve, 9: throttle body, 11a, 11
b: throttle valve, 12: fuel injection passage, 13, 1
5 fuel injector, 14 air cleaner, 16 fuel supply hole, 24 connecting member, 25 introduction pipe, C combustion chamber.

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[Procedure amendment]

[Submission date] February 15, 2000 (2000.2.1
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Engine with multiple intake valves

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine having a plurality of intake valves and a single or a plurality of fuel injectors per cylinder.

[0002]

2. Description of the Related Art An engine equipped with a conventional fuel injector is:
A fuel injector that injects fuel into an intake passage to which air is supplied from an air cleaner is provided. The fuel injector
The fuel injection port is closed with a plunger, and the plunger is sucked and moved by energizing an electromagnetic coil by an injection control device to inject pressurized fuel, a fuel injection valve, an injector, or Also called a fuel injection device.

In an engine having a plurality of intake valves per cylinder, in many cases, one intake passage branches midway into the number of intake valves. Irrespective of the shape of the branch point, the intake air is disturbed regardless of the shape. Therefore, differences in the distance from the intake valve to the position of the branch point cause differences in engine performance and characteristics. Therefore, it is difficult to set the position and shape of the branch point.

In the case of using a fuel injector, a fuel injector is provided upstream of the branch point, and the fuel injector is divided from the fuel injection port toward each of the branched passages so that fuel is injected. It is necessary to devise the shape. in this case,
Unless the fuel injector is an expensive dedicated product, fuel cannot be directed only to the center of the branch passage, so fuel easily adheres to the wall surface, and the fuel adhered to this wall surface may be atomized with a delay, If the fuel adhering to the air enters the combustion chamber with a delay along the wall surface, it may deviate from the intended air-fuel ratio.

On the other hand, an engine in which a fuel injector is provided at a position sufficiently upstream from a branch point of an intake passage (Japanese Patent Laid-Open No.
In the case of -280444), a dedicated fuel injector is not required, but the distance from the fuel injector to the intake port is long, so that the amount of fuel attached to the wall surface increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems. By using a general-purpose fuel injector, the cost can be reduced and a predetermined air-fuel ratio can be obtained. It is another object of the present invention to provide an engine having a plurality of intake valves capable of stabilizing combustion.

[0007]

In order to achieve the above object, an engine according to one aspect of the present invention comprises a plurality of intake ports opening to a combustion chamber, a plurality of intake valves opening and closing these intake ports, includes an intake passage independent plurality of mutually connected to each intake port and a fuel injector for injecting fuel only into one of the plurality of intake passages, each fuel injector
Are separated from each other upstream and downstream of the one intake passage.
And connected by a connecting pipe and provided in the connecting pipe
Fuel is supplied from a common fuel supply hole .

According to the above configuration, since fuel is injected into only one intake passage, there is a difference in density from the intake air from other intake passages. For this reason, the turbulence of the mixture flow in the combustion chamber increases, and the combustion speed can be increased. In addition, as a fuel injector, a general-purpose type that injects fuel into a single conical region in an intake passage that is not branched can be used, so that cost reduction is realized and the fuel is directed to the center of the passage. Thus, the adhesion of fuel to the wall surface can be suppressed.
Further, since a plurality of independent intake passages are formed in the cylinder head, the diameter of each intake passage can be reduced as compared with a configuration in which a branched intake passage is formed. For this reason, the throttle body to which the fuel injector is attached also has a small diameter, so by avoiding interference with the cylinder head, the throttle body is moved closer to the intake port to reduce the length of the intake passage from the fuel injector to the intake port. Since the length can be shortened, the amount of fuel adhering to the wall surface of the intake passage can be further reduced. For this reason, the amount of fuel that enters the combustion chamber with a delay is reduced, and a predetermined air-fuel ratio is obtained, and combustion is stabilized. Further, each fuel injector has one intake passage.
Since it is located separately on the upstream side and downstream side, the fuel on the upstream side
Low intake air temperature due to heat of vaporization of fuel injected from injector
Lowers the charging efficiency and improves the engine output.
You. Also, one fuel injector is suitable for low rotation and low load
The other fuel injector has high injection speed and high load.
Injection characteristics suitable for a wide range of engine operation
Excellent engine performance (fuel, power, etc.) in the turning range
Can be demonstrated. Moreover, each fuel injector is connected by a connecting pipe
The fuel is supplied from a common fuel supply hole provided in the connecting pipe.
As a result, the structure is simplified.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 illustrates the principle of the present invention.
A schematic plan view showing the order, the piston within the bore (not shown)
A cylinder head 2 is attached to the upper part of a cylinder 1 on which the cylinder slides, and a pair of cylinder heads 2 for introducing intake air into a combustion chamber C (FIG. 2) formed by the cylinder 1 and the cylinder head 2. Downstream portions of the intake passages 3a, 3b;
A pair of branched upstream portions 4a and 4b of the exhaust passage 4 are formed. Further, in the cylinder head 2, a pair of intake ports 5a, 5b whose downstream portions open to the combustion chamber C and a upstream portion of the branch exhaust passages 4a, 4b open to the combustion chamber C. Exhaust ports 7a and 7b are formed, and further, as shown in FIG.
intake valves 6a and 6b for opening and closing b, and an exhaust port 7
exhaust valves 8a and 8b for opening and closing the valves a and 7b. 21 and 22 are valve seats.

A throttle body 9 shown in FIG. 1 has one end (downstream end) attached to the cylinder head 2 with bolts 10a and 10b to form a part of the intake passages 3a and 3b. 9 a pair of intake passages 3
a and 3b respectively include throttle valves 11a and 11b.
b is provided. An air cleaner 14 is connected to the other end (upstream end) of the throttle body 9. The upstream ends of the intake passages 3 a and 3 b are inserted into openings 14 a provided downstream of the elements of the air cleaner 14. I have. Further, as shown in FIG. 2, a fuel injection passage 12 is formed through an outer wall of one intake passage 3a of the throttle body 9, and a fuel injector 13 is disposed outside the fuel injection passage 12. The fuel injected from the injection port formed at the tip of the fuel injector 13 is injected into the intake passage 3a through the fuel injection passage 12.

According to the above configuration, since fuel is injected only into one intake passage 3a shown in FIG. 1, there is a difference in density from the intake air from the other intake passage 3b. For this reason, when the intake valves 6a and 6b are opened, the turbulence of the air-fuel mixture in the combustion chamber C increases, and the combustion speed increases.

Further, since the fuel injector 13 can be of a general type for injecting fuel into a single conical area in the intake passage 3a which is not branched, the cost can be reduced and the fuel can be passed through the passage. By directing the fuel toward the center, the adhesion of fuel to the wall surface can be suppressed. Further, since two independent intake passages 3a and 3b are formed in the cylinder head 2, the diameter of each intake passage 3a and 3b can be made smaller than in the case where a branched intake passage is formed. Therefore, the outer diameter of the throttle body 9 is also reduced, so that the throttle body 9 can be brought close to the intake port 5a while avoiding interference with the cylinder head 2, whereby the throttle body 9 in the intake passage 3a can be moved from the throttle body 9 to the intake port 5a.
, The amount of fuel adhering to the wall surface of the intake passage 3a can be reduced. For this reason, the amount of fuel adhering to the wall surface and entering the combustion chamber C with a delay is reduced, a predetermined air-fuel ratio is obtained, and combustion is stabilized.

FIG. 3 is a view showing a cylinder head of another arrangement example of the fuel injector in FIG. In this example,
The fuel injection passage 12 is formed in the wall of the intake passage 3a of the cylinder head 2 without the throttle body 9 (FIG. 2), and the fuel injector 1 is disposed outside the cylinder head 2.
3, fuel is injected through the fuel injection passage 12 toward the vicinity of the valve portion of the intake valve 6a. As a result, the fuel injector 13 is connected to the intake port 5a.
L, that is, the intake passage 3a of the fuel injection passage 12
Passage 3 from the opening center position to the intake port 5a
The distance along a becomes shorter.

According to the above configuration, the fuel is applied to the valve portion of the intake valve 6a having a high temperature to promote vaporization, and the amount of fuel adhering to the wall surface of the intake passage 3a is further reduced, so that the combustion chamber C , The amount of fuel that enters later is further reduced, a predetermined air-fuel ratio is obtained, and combustion can be stabilized.

FIG. 4 is a schematic plan view showing a reference example of the present invention. This reference example includes a second fuel injector 15 disposed in the other intake passage 3b, in addition to a first fuel injector 13 that injects fuel into one intake passage 3a.
The distance L2 from the second fuel injector 15 to the intake port 5b is set larger than the distance L1 from the fuel injector 13 to the intake port 5a.

Further, of the two fuel injectors 13 and 15, the fuel injection amount (fuel supply amount per unit air flow rate) from the second fuel injector 15 having the longer distance L2 is the distance L1.
Is set to be larger than the fuel injection amount from the short fuel injector 13.

According to this embodiment , the second fuel injector 1
The distance L2 from the intake port 5 to the intake port 5b is
Is longer than the distance L1 from the intake port 5a to the intake port 5a, the intake air at the intake port 5b is received from the wall surface because the air-fuel mixture flows at a higher density than the air at the intake port 5a. The frictional resistance becomes larger and the flow velocity becomes slower, the cooling period by the heat of vaporization of the fuel becomes longer, and the temperature decreases and the density becomes higher. Due to the difference between the intake air flow velocity and the difference between the intake air densities, the turbulence of the air flow in the combustion chamber C increases, and the combustion velocity increases.

FIG. 5 is a schematic plan view showing an embodiment of the present invention. This embodiment includes a first fuel injector 13 that injects fuel into one intake passage 3a and a second fuel injector that injects fuel into the intake passage 3a upstream of the first fuel injector 13. 15 are arranged on the downstream side and the upstream side. In the cylinder head 2, a connecting member 24 forming a part of the intake passages 3a, 3b is supported by bolts 10a, 10b.
A throttle body 9 forming a part of 3b is attached.

As shown in FIG. 6, the first fuel injector 13
Is a fuel injection passage 12 formed in the throttle body 9.
The fuel is injected into the intake passage 3a through the passage. On the other hand, the second
The fuel injector 15 opposes the upstream end opening of the intake passage 3a and injects fuel from this opening in the direction of the central axis in the intake passage 3a. The first fuel injector 13 and the second fuel injector 15 are supplied with fuel from a common fuel supply hole 16 provided in a connecting pipe 27 connecting them.

The first fuel injector 13 mainly operates at a low speed.
The second fuel injector 15 has fuel supply characteristics suitable for low load and performs fuel injection over the entire range from idling to high speed rotation, whereas the second fuel injector 15 has fuel supply characteristics suitable for high speed and high load. Is controlled so as to inject fuel over a medium to high speed rotation range and to compensate for the shortage of the injection amount of the first fuel injector 13.

According to this embodiment , similarly to the reference example , a fuel injector having characteristics suitable for idling to medium speed rotation and a fuel injector having characteristics suitable for medium speed to high speed rotation are used. Therefore, suitable rotation characteristics can be obtained over the entire rotation range from idling to a high-speed rotation range.

Further, since the fuel is injected only into one of the intake passages, the temperature difference (density difference) from the intake air from the other intake passage becomes large. Therefore, the turbulence of the air-fuel mixture in the combustion chamber increases, and the combustion speed increases.

[0023]

According to the present invention , since fuel is injected into only one intake passage, a difference in temperature (density difference) from the intake air from the other intake passage occurs. For this reason, the turbulence of the mixture flow in the combustion chamber increases, and the combustion speed increases. Also, since the fuel injector can use a general-purpose type that injects fuel into a single conical area in the intake passage that does not branch,
The cost can be reduced, and the fuel can be prevented from adhering to the wall surface by directing the fuel toward the center of the passage. Further, since a plurality of independent intake passages are formed in the cylinder head, the diameter of each intake passage can be reduced. Therefore, the length of the intake passage can be shortened by bringing the throttle body, to which the fuel injector is attached, closer to the intake port while avoiding interference with the cylinder head, thereby reducing the amount of fuel adhering to the wall of the intake passage. Can be. For this reason,
The amount of fuel that enters the combustion chamber with a delay is reduced, a predetermined air-fuel ratio is obtained, and combustion is stabilized. Further, since a standard type having a single conical expansion can be used as the fuel injector, cost can be reduced. Further
Each fuel injector is located upstream and downstream of one intake passage.
So that the fuel is injected from the upstream fuel injector
Intake air temperature decreases due to the heat of vaporization of
The filling efficiency increases, and the engine output improves. One side
Fuel injection characteristics suitable for low rotation and low load
And the other fuel injector is suitable for high speed and high load
The characteristics make it suitable for a wide range of engine operation.
And excellent engine performance (fuel, power, etc.)
You. Moreover, each fuel injector is connected by a connecting pipe,
Fuel is supplied from a common fuel supply hole in the tube.
Thus, the structure is simplified.

[Brief description of the drawings]

FIG. 1A is a schematic plan view for explaining the principle of the present invention, and FIG. 1B is a cross-sectional view taken along the line AA of FIG.

2 is a longitudinal sectional view showing a cylinder head of FIG.

3 is a longitudinal sectional view showing a modification of the cylinder head of FIG.

FIG. 4 is a schematic plan view showing a reference example of the present invention.

FIG. 5 is a schematic plan view showing one embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing the cylinder head of FIG . 5 ;

[Description of Signs] 1 ... cylinder, 2 ... cylinder head, 3a, 3b ... intake passage, 4 ... exhaust passage, 5a, 5b ... intake port, 6a,
6b: intake valve, 7a, 7b: exhaust port, 8a, 8
b: exhaust valve, 9: throttle body, 11a, 11
b: throttle valve, 12: fuel injection passage, 13, 1
5 fuel injector, 14 air cleaner, 16 fuel supply hole, 24 connecting member, 25 introduction pipe, C combustion chamber.

Claims (3)

[Claims] A plurality of intake ports that open to a combustion chamber; a plurality of intake valves that open and close these intake ports; a plurality of independent intake passages connected to each intake port; An engine having a plurality of intake valves including a fuel injector for injecting fuel into only one. 2. A plurality of intake ports that open to a combustion chamber, a plurality of intake valves that open and close these intake ports, a plurality of independent intake passages connected to each intake port, and fuel into each intake passage. An engine having a fuel injector for injecting and having a plurality of intake valves in which a distance from the fuel injector to an intake port is set to be different for each intake passage. 3. The engine according to claim 1, wherein the plurality of fuel injectors have a plurality of intake valves arranged apart from each other on an upstream side and a downstream side of an intake passage.