JP2002327665A - Fuel supply device for four-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply device for four-cycle engine capable of establishing an improvement of the response even at the time of lean operation, a reduction of the incremental fuel amount for acceleration. a reduction of the emission of unburned HC at the time of fuel cut, etc., by eliminating attachment to the wall surfaces and forming a proper mixture gas quickly which is supplied to a combustion chamber. SOLUTION: The combustion chamber 2 is equipped with a suction passage 3 to introduce the outer air through a suction valve 7, and an injector 15 to inject the fuel is installed in the neighbourhood of a suction port 5 which is opened and closed by the suction valve 7 installed in the suction passage 3, and a fuel injection passage 16 is formed in such an arrangement that the fuel jetted from the injector 15 is injected from the suction port 5 in the tangential direction of the combustion chamber 2, while the suction passage 3 is furnished with a first throttle valve 10 which performs the opening/closing operations from a partial load range to a high load range, and downstream of the first throttle valve 10, a second throttle valve 11 is installed which is closed fully in the partial load range and performs the opening/closing operations in the high load range, and further the fuel injection passage 16 is furnished with an air supplying means which introduces approximately the whole amount of requisite air at the time of partial load and mixes it with the fuel injected from the injector 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Technical field to which the present invention pertains]
It is necessary to further reduce fuel consumption and emission, and leaning of the air-fuel mixture is effective as a measure for improving fuel efficiency.

[0002] The present invention relates to a fuel supply device for introducing an air-fuel mixture into a combustion chamber of a homogeneous premixed lean-burn four-stroke engine.

[0003]

2. Description of the Related Art Conventionally, as a fuel supply device for a four-stroke engine of this type, for example, a swirl control valve is provided on one side of a pair of intake passages, and by closing this valve, a swirl is generated in a combustion chamber. There is one that improves combustion in the partial load range.

A TGV (Tumble Generator Valve:
Fuji Heavy Industries) was installed upstream of the suction port to allow in-cylinder flow (Tumbl
In some cases, e) is enhanced, and atomization is promoted by intake air drift to improve combustion in the partial load region.

[0005]

However, in such a conventional apparatus, since an injector (fuel supply unit) is provided at a position considerably upstream of the intake port, the fuel injected from the injector has a long passage. And then supplied to the combustion chamber, there are many disadvantages such as fuel adhering to the wall surface and poor response. However, simply moving the injector position to the vicinity of the intake valve has a short vaporization time, makes it difficult to form an air-fuel mixture, and causes deterioration of combustion.

[0006] In the case of using a swirl control valve or the like to enhance the in-cylinder flow, the effect of enhancing the flow is low because the valve is installed upstream of the intake port.

[0007] Therefore, the present invention eliminates the adhesion to the wall,
For four-stroke engines that quickly form an appropriate mixture and supply it to the combustion chamber to improve response from lean operation, reduce accelerated fuel increase, and reduce unburned HC emissions during fuel cuts. It is an object to provide a fuel supply device.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, an intake passage for introducing outside air into a combustion chamber via an intake valve is provided, and the intake valve of the intake passage is provided. Near the intake port, which is opened and closed by
A fuel supply unit for injecting fuel is provided, and a fuel injection passage is formed so that fuel injected from the fuel supply unit is injected from the intake port in a tangential direction of the combustion chamber. A first throttle valve that opens and closes from a partial load range to a high load range is provided in the passage, and is fully closed in the partial load range downstream of the first throttle valve to open and close in the high load range. Air supply means for introducing substantially the entire required amount of air at the time of the partial load into the fuel injection passage and mixing the fuel with the fuel injected from the fuel supply unit. A fuel supply device for a cycle engine.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the air supply means is provided in the intake passage,
An upstream end is connected between the first throttle valve and the second throttle valve, and a downstream end is a sub-passage connected to the fuel injection passage. Air is introduced into the fuel injection passage and mixed with fuel injected from the fuel supply unit.

[0010] The invention described in claim 3 is the invention according to claim 1 or 2.
In addition to the above configuration, the air supply unit may further include an upstream end connected to the intake passage upstream of the first throttle valve, and a downstream end connected to the combustion injection passage. Wherein, at the time of the partial load, air is introduced into the fuel injection passage via the other sub-passage, and is mixed with fuel injected from the fuel supply unit. .

[0011] The invention according to claim 4 is the invention according to claims 1 to 3.
In addition to the configuration according to any one of the above, a plurality of the intake ports are provided, and the fuel injection passage is provided corresponding to an endmost intake port among the plurality of the intake ports, The fuel injection unit is characterized in that fuel injected from a fuel supply unit flows from the endmost intake port in a tangential direction of the combustion chamber.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

[First Embodiment of the Invention] FIGS. 1 to 4 show a first embodiment of the present invention.

First, the structure will be described. In the figure, reference numeral 1 denotes a cylinder of a four-cycle engine, in which a combustion chamber 2 is formed, and an intake passage 3 and an exhaust passage 4 are connected to the combustion chamber 2. .

As shown in FIG. 2, the intake passage 3 is bifurcated near the combustion chamber 2 to form two intake ports 5, while the exhaust passage 4 also bifurcates near the combustion chamber 2. It is branched to form two exhaust ports 6.

A pair of intake valves 7 for opening and closing the intake ports 5 and a pair of exhaust valves 8 for opening and closing the exhaust ports 6 are provided, and these valves 7 and 8 are opened and closed at a predetermined timing. It is configured.

In the vicinity of the intake port 5 of the intake passage 3,
Injector 1 as "fuel supply unit" for injecting fuel
The fuel injection passage 16 is formed so that the fuel injected from the injection port 15a of the injector 15 is injected toward the intake port 5 side.

The fuel injection passage 16 is arranged corresponding to one of the intake ports 5 (the endmost intake port 5), and the fuel injected from the injector 15 is burned from the endmost intake port 5. The gas flows in the tangential direction of the chamber 2 and a swirling flow as shown by an arrow in FIG.

On the other hand, the intake passage 3 is provided with a first throttle valve 10 that opens and closes from the partial load region to the high load region on the upstream side, and is provided downstream of the first throttle valve 10. Second throttle valve 1 that is fully closed in a partial load range and opens and closes in a high load range
1 is provided.

An upstream end 14a of an auxiliary passage 14 as "air supply means" is connected between the first throttle valve 10 and the second throttle valve 11 in the intake passage 3. The downstream end 14 b of the sub passage 14 is connected to the fuel injection passage 16.

At the time of partial load, air is introduced from the sub-passage 14 into the fuel injection passage 16 so that the air from the sub-passage 14 flows from the direction orthogonal to the fuel injection direction near the injection port 15a of the injector 15. It is blown and hits fuel,
The fuel is mixed with the fuel injected from the injector 15.

More specifically, as shown in FIGS. 1 and 3, the downstream end 14b has a ring-shaped passage 14d formed around the fuel injection passage 16 in the auxiliary passage 14. 4 from 14d to its fuel injection passage 16
A total of eight communication paths 14e are formed one by one.

As shown in FIG. 3, the communication passages 14e are formed along the radial direction of the fuel injection passage 16 having a circular cross section, and their diameters are set to predetermined values so as to increase the air flow velocity. .

The communication passage 14e may be formed along a direction inclined with respect to the radial direction of the fuel injection passage 16 having a circular cross section. By doing so, it is also possible to form a vortex in the fuel injection passage 16.

Next, the operation will be described.

As shown in FIG. 4, in the partial load range, the amount of air flowing into the combustion chamber 2 is adjusted with the opening of only the first throttle valve 10 with the second throttle valve 11 closed.

In this partial load region, outside air is sucked in through the sub-passage 14 and the injection port 15 of the injector 15
a, and flows into the combustion chamber 2 where it is ignited by a spark plug (not shown) and burned.
Exhaust gas is exhausted from the exhaust passage 4.

In this case, since the injector 15 is disposed near the intake valve 7, the fuel transport distance can be shortened as compared with the related art, so that the response can be improved and the adhesion of the injected fuel to the wall surface can be reduced. Because you can
Emission of unburned fuel during fuel cut / idle stop can be reduced.

The deterioration of the premixing up to the combustion chamber 2 due to the provision of the injector 15 in the vicinity of the intake valve 7 is caused by a large amount of the premixing from the communication passage 14e of the sub passage 14 immediately after the injection port 15a of the injector 15. By introducing air, atomization can be prevented by promoting atomization, and the mixing state can be improved.

Further, in this partial load region, the fuel injection passage 16 is provided on one intake port 5 side in the tangential direction of the combustion chamber 2, so that the fuel injection passage 16 is urged from the fuel injection passage 16 during the intake stroke. Fig. 2
As shown by the middle arrow, the in-cylinder flow is strengthened, and the increased turbulence makes it possible to further promote fuel mixing and combustion after ignition. Thereby, the mixing state can be improved, and the combustion can be improved.

On the other hand, when the vehicle shifts from the partial load region to the high load region, the second throttle valve 11 opens, and outside air is also introduced from the intake passage 3 side.
The fuel is mixed with the fuel injected from the fuel chamber 5 and is taken into the combustion chamber 2.

[Second Embodiment of the Invention] FIGS. 5 and 6 show a second embodiment of the present invention.

The second embodiment differs from the first embodiment in that another sub-passage 19 is provided in addition to the sub-passage 14 of the first embodiment.
This is different from the first embodiment.

The other auxiliary passage 19 has an upstream end 19a.
Is connected to the intake passage 3 on the upstream side of the first throttle valve 10, and the downstream end 19 b of the other auxiliary passage 19 is connected to the fuel injection passage 16. The diameter of the other sub passage 19 is smaller than the diameter of the sub passage 14.

The structure of the downstream end 19b is such that a ring-shaped passage 19d is formed around the fuel injection passage 16 and a total of eight from the ring-shaped passage 19d to the fuel injection passage 16 is formed.
A communication passage 19e is formed.

The communication passages 19e are formed along the radial direction of the fuel injection passage 16 having a circular cross section. The diameter of the communication passage 19e is smaller than the diameter of the communication passage 14e of the sub-passage 14.

According to this, at the time of idling and extremely low load, the amount of assist air through the auxiliary passage 14 is small, so that the combustion is expected to deteriorate. However, it is connected to the upstream side of the first throttle valve 10. Since air is blown into the fuel injection passage 16 through the other auxiliary passage 19, atomization of fuel can be further promoted, and deterioration of combustion can be prevented.

Moreover, the communication passage 19 of the other sub-passage 19
Since e has a small diameter, the flow velocity can be increased even if the amount of air is small, and the atomization of fuel can be further promoted.

In each of the above embodiments, the auxiliary passage 14 is provided as the "air supply means". However, the invention is not limited to this. Of course, it may be possible. Also,
In the first and second embodiments, two intake ports 5 are provided. However, the number of intake ports 5 is not limited thereto.

[0040]

As described above, according to the first aspect of the present invention, since the fuel supply unit is disposed near the intake port, the fuel transportation distance can be reduced as compared with the conventional art, and the response is improved. As a result, it is possible to reduce the adhesion of the injected fuel to the wall surface, thereby reducing the discharge of unburned fuel during fuel cut / idle stop.

The deterioration of premixing up to the combustion chamber due to the provision of the fuel supply unit near the intake port is caused by introducing a large amount of air from the sub-passage immediately after the injection port of the fuel supply unit. This can be prevented by promoting the atomization, and the mixed state can be improved.

Further, in this partial load region, since the fuel injection passage is provided on one intake port side in a direction tangential to the combustion chamber, the fuel injection passage is vigorously injected from the fuel injection passage in the intake stroke. Air enhances the in-cylinder flow, and the increased turbulence promotes further fuel mixing,
It is possible to promote combustion after ignition. Thereby, the mixing state can be improved, and the combustion can be improved.

According to the second aspect of the present invention, in addition to the above effects, the air supply means has an upstream end connected between the first throttle valve and the second throttle valve of the intake passage, and has a downstream end. Since the side end is a sub-passage connected to the fuel injection passage, air can be introduced with a simple structure.

According to the third aspect of the present invention, in addition to the above-described effects, another upstream end is connected to the upstream side of the first throttle valve, and the downstream end is connected to the combustion injection passage. By providing the sub-passage, at the time of idling and extremely low load, the amount of assist air is small, so deterioration of combustion is expected. However, through the other sub-passage connected upstream of the first throttle valve, Since air is blown into the fuel injection passage, atomization of fuel can be further promoted, and deterioration of combustion can be prevented.

According to the fourth aspect of the present invention, the fuel injection passage is provided for the endmost one of the plurality of intake ports, and the fuel injected from the fuel supply unit is provided. In the partial load region, the in-cylinder flow is strengthened by the air-fuel mixture which is vigorously injected from the fuel injection passage in the intake stroke, so that the in-cylinder flow is enhanced. Due to the increase, it is possible to further promote the fuel mixing and the combustion after ignition, and to improve the mixing state and, consequently, the combustion.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a fuel supply device for a four-cycle engine according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of the fuel supply device for a four-cycle engine according to the first embodiment;

FIG. 3 is an enlarged sectional view taken along line AA of FIG. 1 according to the first embodiment;

FIG. 4 is a graph showing a relationship between throttle opening degrees of first and second throttle valves and an engine load according to the first embodiment;

FIG. 5 is a schematic side view of a fuel supply device for a four-stroke engine according to a second embodiment of the present invention.

FIG. 6 is a schematic plan view of a fuel supply device for a four-cycle engine according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Combustion chamber 3 Intake passage 4 Exhaust passage 5 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 10 First throttle valve 11 Second throttle valve 14 Secondary passage (air supply means) 14a Upstream end 14b Downstream end Part 15 Injector (fuel supply part) 16 Fuel injection device 19 Other sub-passage (air supply means) 19a Upstream end 19b Downstream end

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 9/02 361 F02D 9/02 361F 361H 41/04 310C 41/04 310 F02M 69/00 350L 350P F-term (Reference) 3G023 AA01 AA02 AA04 AA17 AB01 AC01 AC02 AD03 AG02 3G065 AA07 CA12 DA04 DA05 EA09 GA41 GA42 GA46 GA47 HA02 HA05 KA01 KA33 3G301 HA01 HA09 HA17 JA01 JA03 JA26 KA07 KA08 KA08 KA13 LA01 MA03 LC02 NE03 LC02 MA03 LC03 PA01 PA01Z PA11Z PE01Z PE06Z

Claims (4)

[Claims] An intake passage for introducing outside air into a combustion chamber via an intake valve is provided, and a fuel supply unit for injecting fuel is disposed in the intake passage near an intake port opened and closed by the intake valve. Forming a fuel injection passage so that fuel injected from the fuel supply unit is injected from the intake port in a tangential direction of the combustion chamber, while forming a fuel injection passage in the intake passage from a partial load region to a high load region. A first throttle valve that performs an opening and closing operation between the first throttle valve and a second throttle valve that is fully closed in a partial load region and performs an opening and closing operation in a high load region downstream of the first throttle valve; An air supply means for introducing substantially all of the required amount of air at the time of the partial load into the injection passage and mixing the fuel with the fuel injected from the fuel supply unit; Fuel supply system for the engine. 2. The air supply means, wherein:
An upstream end is connected between the first throttle valve and the second throttle valve, and a downstream end is a sub-passage connected to the fuel injection passage. 2. The fuel supply device for a four-stroke engine according to claim 1, wherein air is introduced into the fuel injection passage to mix with fuel injected from the fuel supply unit. 3. The air supply means, wherein:
An upstream end is connected to an upstream side of the first throttle valve, and a downstream end is another sub-passage connected to the combustion injection passage. The air is introduced into the fuel injection passage to mix with fuel injected from the fuel supply unit.
Or the fuel supply device for a four-stroke engine according to 2. 4. A plurality of intake ports are provided, and the fuel injection passage is arranged corresponding to an endmost intake port among the plurality of intake ports, and is injected from the fuel supply unit. The fuel supply device for a four-stroke engine according to any one of claims 1 to 3, wherein fuel is introduced from the endmost intake port in a tangential direction of the combustion chamber. .