JPH10196440A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the fuel injection time, to compensate for the difference of the distance between upper and lower fuel injection valves, and to simplify injection control. SOLUTION: A nozzle part 23a of a first fuel injection valve 23 is drawn sideways and attached on a part downstream from a throttle valve 44 in an intake pipe 20, and a second fuel injection valve 36 is arranged on the upstream side of the throttle valve 44 and also above an opening part 42. The injection time can be shortened, the difference of the distance between both fuel injection valves can be compensated for, and control for the fuel injection valves can be simplified by performing injection of respective fuel injection valves for the approximately same time through a process of forming respective fuel injection valves into the approximately same characteristics and hastening the fuel injection start time of the second fuel injection valve 36 earlier than that of the first fuel injection valve 23, or by making a time lag so that the injection having the same amount of the first fuel injection valve 23 may be finished earlier than the second fuel injection valve 36 through a process of forming the fuel injection characteristic of the second fuel injection valve 36 so that the second fuel injection valve may inject fuel having the amount larger than that of the first fuel injection valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device having injection valves provided upstream and downstream of a throttle valve.

[0002]

2. Description of the Related Art Japanese Utility Model Application Laid-Open No. 58-136673 discloses a fuel injection device in which injection valves are respectively provided upstream and downstream of a throttle valve.

A first valve located downstream of the throttle valve
The injection valve and the second injection valve located on the upstream side are respectively arranged to protrude into the suction passage.

[0004]

In the above conventional example, the first
The injection valve and the second injection valve have different characteristics so as to cover different output ranges of the engine, and at the time of maximum outflow, only one main valve controls the entire flow rate so that the main valve controls the entire flow rate. It is set to share roles.

[0005] Therefore, in order to cope with a high-power engine, the injection time by one main injection valve is prolonged in order to increase the maximum flow rate. Therefore, the fuel injection cannot be completed from the start to the end within the stroke of opening the intake valve, and it is difficult to sufficiently increase the charging efficiency.

On the other hand, if the fuel injection volume is increased or a high injection pressure is applied, the fuel injection at a low flow rate tends to become unstable, so that different control is performed on the main side and the auxiliary side. However, such control becomes extremely complicated, and the design of a control circuit such as an ECU becomes complicated and expensive.

Further, when the flow rate is controlled by one main injection valve, it is remarkable that a high efficiency is maintained over the entire rotation speed range, especially in a motor having a very wide rotation speed range such as a motorcycle. It becomes difficult.

[0008]

To solve the above-mentioned problems, a fuel injection device according to the present invention comprises an intake pipe provided with a throttle valve at an intermediate portion, and a first fuel pipe provided downstream of the throttle valve. In a fuel injection device for an internal combustion engine including an injection valve and a second fuel injection valve provided upstream of a throttle valve, the injection times of the first injection valve and the second injection valve are made substantially the same, The fuel injection start timing of the second injection valve is started earlier with a time difference from the first injection valve.

In a fuel injection system having the same premise, the fuel injection amount of the first injection valve and the fuel injection amount of the second injection valve are made substantially the same, and the fuel injection end timing of the second injection valve is set to the first injection valve. A time lag may be provided so as to end earlier.

Further, in any of these cases,
The time difference provided at the fuel injection start or end timing can be made variable in accordance with the engine operating state.

【The invention's effect】

The second fuel injection valve on the upstream side starts fuel injection at a slightly earlier timing than the first fuel injection valve on the downstream side by a time difference Δt 1, and each of them has almost the same characteristics and the same injection time. In this case, the respective fuel injection amounts are substantially the same.

On the other hand, if an attempt is made to inject the same amount as the total fuel injection amount of the first and second fuel injection valves by one main fuel injection valve, the fuel injection is started at a timing considerably earlier than the opening of the intake valve. The injection time is considerably longer.

Therefore, as in the present invention, for example, when the fuel injection is performed simultaneously with the first fuel injection valve and the second fuel injection valve having substantially the same characteristics, the injection time is shorter than the case where only one main fuel injection valve is used. Can be reduced to about ２, and the required amount of fuel can be injected within the time when the intake valve is open.

Further, by setting a time difference Δt 1 at the start of fuel injection between the first fuel injection valve and the second fuel injection valve,
The distance between the second fuel injection valve and the first fuel injection valve can be compensated.

Further, since the flows of the injected fuel of the first fuel injection valve and the flow of the injected fuel of the second fuel injection valve interfere with each other, the atomization of the fuel is promoted and the output of the engine is improved.

In addition, since the injection control of the first fuel injection valve and the second fuel injection valve can be performed simply by adding a difference Δt1 to the fuel injection start time, the fuel injection control becomes extremely simple.

Further, the fuel injection amount of the second fuel injection valve on the upstream side is made larger than that of the first fuel injection valve on the downstream side, and the same amount as the total fuel injection amount of the first fuel injection valve is compared with the time difference △. The injection is terminated earlier by t2.

In this case, the same effect can be obtained, and even if the fuel injection amount from the second fuel injection valve is large, the throttle is once throttled near the throttle valve, so that atomization is promoted. Can be shortened.

If the time difference Δt1 or Δt2 is made variable by correlating it with the amount of engine operation such as throttle opening and engine speed, the output can be more effectively improved in any case. it can.

In any of the above cases, it is possible to stabilize the fuel injection at a low flow rate. In particular, even when the rotational speed range is extremely wide as in a motorcycle, the rotational speed can be reduced. It is easy to maintain high efficiency over the entire area.

[0021]

FIG. 1 is a sectional view showing an intake structure according to the present invention for one cylinder, FIG. 2 is a side view showing a main part of an external appearance of a motorcycle of a race specification to which the present invention is applied, FIG. 3 is a side view of the throttle body according to the present invention, and FIG. 4 is a plan view of the same.

First, in FIG. 2, an intake box 2 is disposed between main frames 1 extending in the front-rear direction in a left-right pair.

A throttle body 3 to be described later is accommodated in the intake box 2, and a lower portion thereof is located in a valley between a front cylinder 5 and a rear cylinder 6 of a V-type four-cylinder engine 4 which is an example of an internal combustion engine. Downdraft is taken into the cylinder.

The upper portion of the intake box 2 protrudes above the main frame 1, is accommodated in a recess formed in the bottom of the fuel tank 7, and has an outside air intake.

An air duct 8 having one end connected to the outside air inlet penetrates through the fuel tank 7 and connects to an opening formed at the front of the fairing 9, from which the traveling wind flows into the intake box 2. It is supposed to be introduced.

The rear end of the fuel tank 7 is mounted and supported on a seat rail 10 extending from the rear end of the main frame 1, and a seat 11 is supported on the seat rail 10 behind the fuel tank 7.

The V-type four-cylinder engine 4 has an engine hanger 12 extending downward from the main frame 1 in left and right pairs.
And it is supported by a pivot plate 13 extending downward from the rear end of the main frame 1.

A front end of a cantilevered rear arm 14 is pivotally supported by a pivot portion 15 on a pivot plate 13, and a rear wheel 16, which is cantilevered at one rear end, is connected to a V-shape via a chain 17.
It is driven by a type 4 cylinder engine 4.

As is apparent from FIGS. 3 and 4, the throttle body 3 is a quadruple type, and four funnel-shaped intake pipes 20 corresponding to the respective cylinders are integrally formed on a common main body 21. Have been.

Of the intake pipes 20, the front two pipes are for the front cylinder and the rear two pipes are for the rear cylinder, and the front intake pipe 20 and the rear intake pipe 20 are paired in the left-right direction. What 2
Each is provided.

A socket 22 is formed in a main body 21 on the side of each intake pipe 20, and a first fuel injection valve 2 having a well-known structure is provided here.
3 are fitted.

Each first fuel injection valve 23 is connected to a main fuel passage 25 formed at the center of the main body 21 via a branch fuel passage 24.
Is in communication with

The main fuel passage 25 is connected to a fuel pump (not shown) through a joint pipe 26, and the fuel supplied from the fuel tank 7 by the fuel pump is distributed from the main fuel passage 25 to each first fuel injection valve 23. Have been.

A drum 28 operated by a throttle wire 27 is attached near the joint pipe 26.
A throttle valve (described later) provided in each intake pipe 20 is opened / closed via a link mechanism.

Further, a passage member 31 having an upper fuel passage 30 is disposed above and below each of the front and rear intake pipes 20 in a front-rear pair.

The upper fuel passage 30 is substantially parallel to the main fuel passage 25, is disposed so as to cross over the openings of the front and rear left and right intake pipes 20, and is connected to a fuel pump (not shown). Have been.

As is apparent from FIG. 3, the passage member 31 is supported by a bolt 34 on a transverse plate 33 disposed above the opening of each intake pipe 20 via a collar 35 by a mounting portion 32 projecting laterally. Have been.

A second fuel injection valve 36 having substantially the same injection characteristics as the first fuel injection valve 23 is provided in the passage member 31 in the up-down direction. 2 communicates with the fuel passage 30 and the lower end is a transverse plate 33
Is supported in a state where it passes through.

The transverse plate 33 is attached with a nut 39 to a screw portion 38 formed at the upper end of a column 37 projecting upward and parallel to the upper surface of the intake pipe 20 with an opening therebetween.

The lower portion of the column 37 is attached to the edge 41 by screwing the screw portion 40 into a screw hole provided in the edge portion 41 surrounding the opening of the intake pipe 20.

As is apparent from FIG. 1 showing only an enlarged portion of the intake pipe 20 connected to the front cylinder 5, the intake pipe 20
The diameter D of the opening 42 at the upstream end and the nozzle portion 3 which is the tip of the second fuel injection valve 36 from the opening 42
The ratio H / D of the distance H to the distance 6a is set to be 0.5 or more.

An intake passage 43 in the intake pipe 20 is formed substantially straight in the vertical direction, and a throttle valve 44 is provided at an intermediate portion thereof.

A recess 45 is formed in the side wall of the intake pipe 20 below (downstream) the throttle valve 44, and a nozzle portion 23a, which is the tip of the first fuel injection valve 23, is formed here.
Is protruding.

However, the nozzle portion 23 of the first fuel injection valve 23
a is drawn into the side without protruding into the intake passage 43, and the injection direction axis C1 which is the central axis thereof.
Are inclined so as to intersect the central axis C0 of the intake passage 43.

In addition, above the throttle valve 44 (upstream side)
The second fuel injection valve 36 is located at the center, and the injection direction axis C2, which is the center axis thereof, is substantially parallel to the center axis C0 of the intake passage 43, and the nozzle portion 36a has an opening when viewed along the injection direction axis C2. 42.

A lower end 46 of the intake pipe 20 is connected to an intake passage 48 of the front cylinder 5 via an insulator 47, and an intake port 49 facing a combustion chamber of the intake passage 48 is opened and closed by an intake valve 50. Has become. The rear cylinder has the same structure.

The intake box 2 covers the entire throttle body 3 except for the lower end 46. When the intake box 2 is attached to the front cylinder 5 and the rear cylinder 6, it is connected to the outside through the air duct 8, except for the throttle body. 3 can be almost sealed.

Next, the operation of the present embodiment will be described. In this example, the second
The first fuel injection valve 23 is provided from the downstream side by the fuel injection valve 36.
As a result, fuel is injected into the intake passage 43 almost simultaneously.

FIG. 5 is a view showing an example of fuel injection of the first fuel injection valve 23 and the second fuel injection valve 36. That is, when the intake valve 50 is opened once during two revolutions of the crankshaft, first, the upstream second fuel injection valve 36 is connected to the intake valve 5.
The fuel injection starts at a timing slightly earlier than the start of the opening of the fuel injection valve 0, and after the time Δt1, the first fuel injection valve 2 on the downstream side
3 starts fuel injection.

The end of the fuel injection of the first fuel injection valve 23 substantially coincides with the closing timing of the intake valve 50, and the end of the fuel injection of the second fuel injection valve 36 ends Δt2 time earlier than the first fuel injection valve 23. .

Here, when the first fuel injection valve 23 and the second fuel injection valve 36 have substantially the same characteristics, if the injection times T1 and T2 are the same (△ t1 = △ t2), the respective The fuel injection amount is also substantially the same.

On the other hand, if an attempt is made to inject the same amount of fuel as the total fuel injection amount of the first fuel injection valve 23 and the second fuel injection valve 36 with one main fuel injection valve, it is much earlier than the opening of the intake valve 50. Since the fuel injection must be started at the timing and maintained until almost the same timing as the end of the first fuel injection valve 23, the injection time becomes considerably long.

Therefore, when fuel injection is performed simultaneously by the first fuel injection valve 23 and the second fuel injection valve 36 as in this example, the injection time is reduced by about 1 / compared to the case where only one main fuel injection valve is used. 2 and the required amount of fuel can be injected within the time when the intake valve 50 is open.

Further, the distance between the second fuel injection valve 36 and the first fuel injection valve 23 is compensated by setting a time difference Δt1 at the start of fuel injection between the first fuel injection valve 23 and the second fuel injection valve 36. be able to.

Further, since the flows of the injected fuels of the first fuel injection valve 23 and the second fuel injection valve 36 interfere with each other,
Fuel atomization is promoted, and the output of the engine is improved.

In addition, since the first fuel injection valve 23 and the second fuel injection valve 36 have substantially the same characteristics, it is only necessary to provide a difference Δt1 to the fuel injection start time, so that the fuel injection control is extremely simple. become.

Further, the fuel injection at a low flow rate can be stabilized. In particular, even when the rotational speed range is extremely wide as in a motorcycle, high efficiency can be maintained over the entire rotational speed range. It is easier and more effective for race specification cars.

FIG. 7 shows an output curve with respect to the engine speed of the engine to which the present embodiment is applied. The solid line is an output curve when the first fuel injection valve 23 and the second fuel injection valve 36 are used together.

The dashed line indicates the output curve of the first fuel injection valve 23 on the downstream side during single injection, and the dashed line indicates the output curve of the second fuel injection valve 36 on the upstream side during single injection. On the other hand, it is apparent that better output characteristics can be obtained when the solid line is used together.

It should be noted that the first fuel injection valve 23 and the second
The fuel injection amount characteristics of the fuel injection valves 36 do not have to be the same. What is indicated by a virtual line in FIG. 5 is this example.

That is, the fuel injection start of the upstream second fuel injection valve 36 is made to coincide with the downstream first fuel injection valve 23. However, the fuel injection amount of the second fuel injection valve 36 is made larger than that of the first fuel injection valve 23, and the same amount as the total fuel injection amount of the first fuel injection valve 23 is ended earlier by the time difference Δt2. .

In this manner, the same effect can be obtained, and the fuel injected from the second fuel injection valve 36 is throttled once in the vicinity of the throttle valve 44 even if it has a large injection amount. Is promoted, so that the injection time can be shortened.

If the time difference Δt 1 or Δt 2 is made variable by correlating it with the amount of engine operation such as throttle opening and engine speed, the output can be more effectively improved in any case. it can.

Further, in this fuel injection, the second fuel injection valve 36 is separated by a distance H above the nozzle portion 36a outside the opening portion 42, and the nozzle portion 23a of the first fuel injection valve 23 is Since it is drawn into the concave portion 45, it does not protrude into the intake passage 43, and the ventilation resistance is reduced.

In particular, when the second fuel injection valve 36 is set to H / D ≧ 0.
5 is important, and FIG. 6 is a graph showing the relationship between H / D and engine output (PS).

As is clear from this figure, the output of the engine sharply rises when the H / D is around 0.5 and then saturates to a plateau state. It means to reduce as much as possible.

In this embodiment, the second fuel injection valve 36 is set in this range, and by setting it near the inflection point of 0.5, it is possible to minimize the scattering of the injected fuel outside the intake pipe. Therefore, a large amount of fuel can be secured, and the second fuel injection valve 36
Is provided on the upstream side of the throttle valve 44, the ventilation resistance can be reduced most efficiently and the output of the engine can be increased.

Further, by making the injection direction axis C2 of the second fuel injection valve 36 substantially parallel to the central axis C0 of the intake pipe 20, the fuel injected from the nozzle portion 36a can be
Since the ratio of maintaining the atomized state without wetting the 0 wall is increased, the atomized fuel is efficiently charged into the intake pipe 20.

Further, since the entire throttle body 3 is surrounded by the intake box 2, the second
Despite the provision of the fuel injection valve 36, it is possible to prevent the fuel vapor accompanying the fuel injection from the second fuel injection valve 36 from being scattered to the surroundings by the intake box 2, thereby contributing to the prevention of air pollution.

FIG. 8 is a principle diagram in the case where the present invention is applied to an in-line four-cylinder type automobile engine. A throttle valve 62 is provided in an intake pipe 61 of the engine 60, and a first fuel An injection valve 63 is provided, and a second fuel injection valve 64 is provided upstream of the throttle valve 62 and above the intake pipe 61.
Is provided.

The intake pipe 61, the first fuel injection valve 63 and the second fuel injection valve 64 are surrounded by an intake box 65, which is connected to an air cleaner 66.

In this case, it is natural that the above-described effects are obtained, and it is apparent that the present invention can be applied regardless of the type of the engine (internal combustion engine) and the number of cylinders.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an intake structure according to the present invention for one cylinder;

FIG. 2 is a side view showing a main part of an appearance of a motorcycle to which the present invention is applied.

FIG. 3 is a side view of the throttle body according to the present invention.

FIG. 4 is a plan view of the same.

FIG. 5 is a graph showing a fuel injection pattern.

FIG. 6 is a graph showing a relationship between an opening diameter of an intake passage and a distance from a fuel injection valve.

FIG. 7 is a graph showing an output curve of the engine according to the present invention.

FIG. 8 is a principle diagram when the present invention is applied to an automobile engine.

[Explanation of symbols]

2: intake box, 3: throttle body, 20: intake pipe, 23: first fuel injection valve, 36: second fuel injection valve, 4
2: Opening, 44: Throttle valve

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI F02M 69/00 350L 350P

Claims (4)

[Claims] An intake pipe provided with a throttle valve in an intermediate portion; a first fuel injection valve provided downstream of the throttle valve; and a second fuel injection valve provided upstream of the throttle valve. In a fuel injection device for an internal combustion engine having
The injection time of the first injection valve and the injection time of the second injection valve are made substantially the same, and the fuel injection start timing of the second injection valve is started earlier with a time difference with respect to the first injection valve. Fuel injector. 2. The fuel injection device according to claim 1, wherein the time difference is variable according to an engine operating state. 3. An intake pipe provided with a throttle valve at an intermediate portion, a first fuel injection valve provided downstream of the throttle valve, and a second fuel injection valve provided upstream of the throttle valve. In a fuel injection device for an internal combustion engine having
The fuel injection amounts of the first injection valve and the second injection valve are made substantially the same, and a time difference is provided so that the fuel injection end timing of the second injection valve ends earlier than the first injection valve. Fuel injector. 4. The fuel injection device according to claim 3, wherein the time difference is variable in accordance with an engine operating state.