JPH1061530A - Throttle body structure of fuel injection-type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throttle body structure of a fuel injection-type internal combustion engine, capable of adjusting the assist air amount without complicating the structure. SOLUTION: A throttle body 24 is connected to an intake port 18 of an engine 11 through an intake manifold 20 and a surge tank 23. The throttle body 24 is provided with a throttle valve 26 capable of being rotated around a rotary shaft 26a. The throttle valve 26 adjusts the passage sectional area of an air passage 25. An assist air port 30 is provided on the throttle body 24. This port 30 is connected to an annular passage 34 provided near a nozzle tip 21a of a fuel injection valve 21 through a passage 31, an air delivery pipe 32 and an assist air introducing pipe 33. The area of a part in the port 30, positioned upstream from the throttle valve 26 is changed by the opening and closing operation of the valve 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine provided with an air assist mechanism for promoting atomization of fuel injected and supplied from a fuel injection valve. More specifically, the present invention relates to a throttle body structure forming an intake passage of the engine.

[0002]

2. Description of the Related Art Generally, in a fuel injection type internal combustion engine, fuel is injected from a fuel injection valve into an intake passage or a combustion chamber. The injected fuel is burned together with the air introduced into the combustion chamber through the intake passage, and the combustion provides a driving force to the internal combustion engine. Here, the fuel injected from the fuel injection valve needs to be atomized to an appropriate particle size. When the particle size of the fuel is relatively large, good combustion in the combustion chamber cannot be ensured. As a result, the combustion efficiency of the internal combustion engine is significantly reduced, and the emission may be deteriorated. Therefore, a device for promoting atomization of fuel injected from a fuel injection valve has been conventionally proposed.

[0003] Japanese Patent Application Laid-Open No. 61-87940 discloses a "vehicle fuel supply device" designed to atomize fuel. As shown in FIG. 14, this fuel supply device includes a throttle body 101 forming an intake passage of an internal combustion engine.
And a throttle valve (throttle valve) 102 and a fuel injection valve 10 provided on the throttle body 101, respectively.
3 is provided. Main passage 106 of throttle body 101
The throttle valve 102 provided in the main passage 10
The amount of air that passes through 6 and is introduced into a combustion chamber (not shown) is adjusted. The fuel injection valve 103 injects and supplies fuel from the injection port 103 a into the main passage 106. The air groove 105 formed around the injection port 103a is
06. The downstream end of the secondary air passage (sub-passage) 104 formed in the throttle body 101 communicates with the air groove 105. The upstream end of the sub passage 104 opens to the main passage 106 upstream of the throttle valve 102.

The flow of air in the main passage 106 is restricted by a throttle valve 102. For this reason, the internal pressure on the upstream side of the throttle valve 102 is substantially equal to the atmospheric pressure, whereas the internal pressure on the downstream side of the valve 102 is a negative pressure corresponding to the opening degree. As a result, a pressure difference occurs between the upstream side and the downstream side of the throttle valve 102 in accordance with the opening degree. For this reason, a part of the air upstream of the throttle valve 102 passes through the sub-passage 104 and flows to the downstream end thereof, and passes again through the air groove 105 to the main passage 106.
Will be introduced. In this manner, the main passage 1
The air flowing to 06 is referred to as assist air. The assist air acts on the fuel injected from the injection port 103a to promote atomization of the fuel.

[0005]

In the above-mentioned fuel supply device, more assist air is required to further promote atomization of fuel. Therefore, the sub passage 104
It is conceivable to increase the assist air amount by increasing the cross-sectional area of the flow path. In such a case, although atomization of the fuel is promoted, the increased assist air is always supplied to the combustion chamber of the internal combustion engine through the auxiliary passage 104. Therefore, for example, when the opening of the throttle valve 102 is reduced during idling, the engine speed cannot be sufficiently reduced by the amount of the assist air. As a result, fuel efficiency and emission may deteriorate. For this reason, according to the fuel supply device, when the internal combustion engine is idling, suppressing the engine speed is a limiting factor, and the assist air amount cannot be sufficiently increased.

On the other hand, it is conceivable to provide a flow control valve in the auxiliary passage 104 and adjust the amount of assist air by using the valve. That is, by controlling the opening of the flow control valve, the assist air amount is reduced when the internal combustion engine is idling, and the assist air amount is increased when a large amount of fuel is injected from the fuel injection valve 103. However,
In such a configuration, the structure and control contents are complicated because a separate flow control valve is required.

The present invention has been made in view of such circumstances, and has as its object the throttle body structure of a fuel injection type internal combustion engine capable of adjusting the amount of assist air without complicating the structure. Is to provide.

[0008]

According to a first aspect of the present invention, there is provided an intake passage for introducing air to an internal combustion engine, and fuel is supplied to the internal combustion engine. And a part of the air in the intake passage is introduced as assist air into the assist air passage, and the assist air is discharged from the vicinity of the nozzle tip of the fuel injection valve into the intake passage through the assist air passage. A throttle body structure of a fuel injection type internal combustion engine having an air assist mechanism for promoting atomization of fuel injected from a nozzle tip, and having an internal passage forming a part of an intake passage. A throttle body having a cylindrical shape, and a slot provided in the internal passage upstream of the fuel injection valve for adjusting the amount of air introduced into the internal combustion engine. And a valve, provided with openings for the assist air introduction upstream portion of the assist air passage opening into the internal passage is connected to the throttle body,
The gist is that the effective opening area of the opening is changed by a throttle valve whose position changes according to the opening degree. In this specification, "effective opening area"
Is defined as the opening area of a portion of the opening of the assist air passage provided on the throttle body side, which is located on the upstream side of the throttle valve, that is, the portion located in the atmospheric pressure region.

According to the above configuration, the flow passage cross-sectional area of the intake air passing through the throttle body is reduced by the throttle valve, so that a pressure difference is generated between the upstream and downstream sides of the valve. Due to this pressure difference, a part of the air in the throttle body is introduced into the assist air passage as assist air, and is discharged from the vicinity of the nozzle tip of the fuel injection valve into the intake passage through the passage. Thereby, atomization of the fuel injected from the nozzle tip is promoted.

[0010] The throttle valve changes the effective opening area of the opening of the internal passage to which the upstream portion of the assist air passage is connected. Since the assist air amount is determined by the size of the effective opening area, the assist air amount is adjusted according to the opening degree of the throttle valve reflecting the operating state of the internal combustion engine.

In order to achieve the above object, according to a second aspect of the present invention, in the first aspect, the opening is a plurality of holes or a long hole extending along a circumferential direction of the throttle body. That is the purpose.

According to the above construction, in addition to the operation of the first aspect, the opening is formed as a plurality of holes or a long hole extending in the circumferential direction of the throttle body. The maximum amount increases. Further, unlike the configuration in which the area of the opening is simply increased to increase the maximum amount of the assist air, the assist air is reliably introduced into the assist air passage.

In order to achieve the above object, a third aspect of the present invention is directed to the first or second aspect, wherein the opening is provided when the throttle valve is fully closed. It is intended that a part thereof is located upstream of the throttle valve.

According to the above configuration, in addition to the operation of the first or second aspect, even when the throttle valve is fully closed, the opening portion located upstream of the throttle valve opens the assist air passage. Assist air is introduced to
A minimum assist air amount is secured.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] Hereinafter, a first embodiment in which the first invention is embodied in a throttle body structure of a gasoline engine mounted on a vehicle will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an electronically controlled fuel injection gasoline engine (hereinafter, referred to as “engine”) 11 as an internal combustion engine. FIG. 3 shows a section taken along line 3-3 in FIG.

The engine 11 has a plurality of cylinder bores 15
, A cylinder block 13 for accommodating the piston 12 in a reciprocating manner, a cylinder head 14 disposed on the cylinder block 13, the head 14, the cylinder bore 1
5 and a plurality of cylinders including a combustion chamber 16 defined by the piston 12 (only one cylinder is shown in FIG. 1). Intake valve 17 provided on cylinder head 14
An exhaust valve (not shown) selectively opens and closes an intake port 18 and an exhaust port (not shown) formed in the head 14.

An intake manifold 20 connected to the intake port 18 introduces air into the port 18. A fuel injection valve 21 provided in the intake manifold 20 injects fuel supplied from a fuel pump (not shown) through a fuel line 22 toward the intake port 18. The injected fuel is mixed with air introduced into the intake port 18 to form an air-fuel mixture, and flows into the combustion chamber 16 when the intake valve 17 is opened. The fuel injection valve 21 is an electromagnetic valve that opens and closes according to an energization signal. The electronic control unit mounted on the vehicle
The ECU 50 outputs a predetermined energization signal to the fuel injection valve 21 to control the amount of fuel injected from the fuel injection valve 21 and the injection timing.

A surge tank 23 connected upstream of the intake manifold 20 functions to reduce pulsation of the intake air. A throttle body 24 is connected to an upstream side of the surge tank 23. The intake air introduced into the throttle body 24 via an air cleaner (not shown)
The gas passes through the surge tank 23 and the intake manifold 20 in order and is introduced into the intake port 18. Throttle body 24,
The surge tank 23 and the intake manifold 20 constitute an intake passage in the present invention.

The throttle body 24 has an internal passage 25 having a circular cross section through which intake air passes. A substantially disc-shaped throttle valve 26 disposed in the internal passage 25 is a throttle valve for restricting a flow path of the intake air passing through the throttle body 24, and has a rotation angle (opening degree) about a rotation shaft 26a thereof. TA), the amount of intake air passing through the internal passage 25 from the upstream side to the downstream side of the valve 26 (hereinafter referred to as "valve passing air amount Q2").
Adjust).

A stepping motor 27, which is drivingly connected to a rotary shaft 26a of the throttle valve 26, changes the opening TA by rotating the coaxial 26a. ECU50
Calculates the target opening of the throttle valve 26 based on the operating state of the engine 11 detected by various sensors 51 (for example, an accelerator opening sensor, an intake pressure sensor, an engine rotation speed sensor), and calculates the actual opening. TA
Is controlled to match the target opening degree.

The throttle body 24 has an assist air port 30 as an opening for taking out assist air. As shown in FIGS. 1 and 3, when the throttle valve 26 is in the fully closed position (the position indicated by the broken line in FIG. 1), the port 30 is located downstream (right side in FIG. 1) of the valve 26. It is formed so that it may be located.

An air delivery pipe 32 connected to the port 30 via a passage 31 distributes and supplies assist air to an assist air introduction pipe 33 provided for each cylinder. The introduction pipe 33 is formed around the nozzle tip 21 a of the fuel injection valve 21, and opens into an annular passage 34 that communicates with the intake manifold 20. Thus, port 3
0 is connected to the downstream side of the throttle valve 26 through the passages 31 and 34, the air delivery pipe 32, and the introduction pipe 33. The port 30, each passage 31, 34, and the introduction pipe 33 constitute an assist air passage 35.

The operation and effect of the present embodiment configured as described above will be described. The flow of air in the internal passage 25 is restricted by a throttle valve 26. Therefore, in the internal passage 25, the throttle valve 26
The internal pressure on the downstream side becomes a negative pressure according to the opening degree of the valve 26, which is smaller than the internal pressure on the upstream side (substantially atmospheric pressure). Therefore,
In the internal passage 25, a pressure difference is generated on the upstream side (atmospheric pressure region) and downstream side (negative pressure region) of the throttle valve 26 in accordance with the degree of opening. When the relative position of the port 30 is located on the upstream side of the throttle valve 26 with the opening operation of the throttle valve 26, that is, when the port 30 is located in the atmospheric pressure region, the port 30 is caused by the pressure difference. , A part of the air in the internal passage 25 is introduced as assist air.

An annular passage 34 passes through the port 30, the passage 31, the air delivery pipe 32, and the introduction pipe 33 in this order.
Is discharged from the passage 34 into the intake manifold 20 and the intake port 18.
The assist air acts on the fuel injected from the fuel injection valve 21 to promote atomization of the fuel.

FIG. 2 shows the vicinity of the port 30 in an enlarged manner. FIG. 4 shows the relationship between the opening degree TA of the throttle valve 26 and the engine intake air amount Qsum when the pressure difference between the upstream side and the downstream side of the throttle valve 26 is maintained at a constant value. Here, the engine intake air amount Qsum is the sum of the valve passing air amount Q2 and the amount of air introduced into the combustion chamber 16 through the assist air passage 35 without passing through the throttle valve 26, that is, the assist air amount Q1. is there. Hereinafter, when the opening degree TA of the throttle valve 26 is in the fully closed position (opening degree TA = 0) as shown by the broken line in FIG. 2, θ3 as shown by the solid line in FIG.
The changes in the valve passing air amount Q2 and the assist air amount Q1 in the present embodiment will be described by taking an example of the case where the air pressure increases to.

When the throttle valve 26 is in the fully closed position (broken line), the port 30 is located downstream of the valve 26,
That is, it is located in the negative pressure region. Accordingly, since there is almost no pressure difference between the vicinity of the port 30 and the vicinity of the nozzle tip 26a, the assist air amount Q1 is substantially "0".
Similarly, the valve passing air amount Q2 is "0".

Next, as the opening degree TA increases to θ1, the valve passing air amount Q2 increases to a predetermined amount Q21. On the other hand, the assist air amount Q1 remains at "0" and does not increase. This is because the port 30 is located in the negative pressure region.

As the opening degree TA further increases from θ1 (the state shown by the two-dot chain line), the amount of air passing through the valve Q2 increases and the amount of assist air Q1 also starts to increase.
This is because a portion of the port 30 is located upstream of the throttle valve 26, that is, in the atmospheric pressure region, and air is introduced into the port 30 from the portion located in the atmospheric pressure region due to the pressure difference. Because it becomes.
Then, as the opening degree TA further increases from θ1,
Area of a portion located in the atmospheric pressure region in the port 30;
That is, since the effective opening area increases, the assist air amount Q1 increases with the increase.

As the opening degree TA increases to θ2 (a state shown by a dashed line; for example, it corresponds to “10 °”), the ports 30 are all located on the upstream side of the throttle valve 26 as shown in FIG. That is, it is located in the atmospheric pressure region. Therefore, even if the opening degree TA further increases from θ2 to θ3, the effective opening area does not increase, so that the assist air amount Q1 does not increase at the predetermined amount Q11 as shown in FIG.
Only the valve passing air amount Q2 increases.

As described above, according to the present embodiment, the port 30 is opened and closed by opening and closing the throttle valve 26.
The effective opening area is changed. Thus, the assist air amount Q1 can be increased from "0" to the predetermined amount Q11 with an increase in the opening TA.

For example, when the opening degree TA is small as in the case of the idle ring of the engine 11, the assist air amount Q1 can be set to "0" or a very small amount. Therefore, it is possible to avoid a situation in which a large amount of assist air is introduced into the combustion chamber 16 through the assist air passage 35 and the engine rotation speed cannot be reduced. On the other hand, when the opening degree TA increases, a sufficient amount of assist air can be secured because the effective opening area increases with the increase.
Therefore, the fuel injected from the fuel injection valve 21 can be sufficiently atomized.

In particular, in this embodiment, the opening of the throttle valve 26 is opened and closed by a stepping motor 27 controlled by the ECU 50. Therefore, when the engine 11 is idling, the opening degree TA of the throttle valve 26 is controlled by the ECU 50 so that the engine rotation speed matches the target rotation speed.
Further, in this embodiment, when the throttle valve 26 is in the low opening range (0 ° <TA <10 °), the port 30 is formed at a position where the effective opening area is changed by the valve 26. . Therefore, according to the present embodiment,
During idling when the opening TA of the throttle valve 26 is in the low opening region, the assist air amount Q1 can be changed according to the opening TA. At the time of idling, the fuel injection amount decreases, so that the combustion in the combustion chamber 16 tends to be unstable. However, according to the present embodiment, even during such idling, the assist air amount Q1 is changed so as to increase in accordance with the increase in the opening degree TA of the throttle valve 26. As a result, atomization of the fuel can be promoted, thereby stabilizing combustion.

As described above, according to the present embodiment, the assist air amount Q1 can be suitably adjusted according to the opening degree TA of the throttle valve 26, which is a parameter indicating the operating state of the engine 11.

According to the present embodiment, the assist air amount Q1 can be adjusted by changing the effective opening area of the port 30 using the existing throttle valve 26. Therefore, the assist air amount Q
Unlike the case where a flow rate adjusting mechanism such as a flow rate control valve for adjusting 1 is separately provided, the assist air amount Q1 can be adjusted with an extremely simple configuration.

[Second Embodiment] Next, a second embodiment of the second invention will be described with reference to FIGS. 5 to 7, focusing on differences from the first embodiment. . In the present embodiment, for the same configuration as the first embodiment,
The same reference numerals are given and the description is omitted.

FIG. 5 shows the throttle body 24 and the like in this embodiment, and FIG. 6 is a sectional view taken along the line 6-6 in FIG. As shown in FIGS. 5 and 6, the throttle body 24 in the present embodiment has a plurality (five) of lead-out holes 36 as openings for taking out assist air. As shown in FIG. 6, the outlet holes 36 are arranged in a line along the circumferential direction of the throttle body 24, and when the throttle valve 26 is fully closed (the state shown by the broken line in FIG. 6). , And downstream of the valve 26 (right side in the figure). In the present embodiment, the diameter of each outlet hole 36 is set to “2 mm”.

At the position on the outer peripheral surface of the throttle body 24 that covers each outlet hole 36, an assist air extracting member 37 is provided.
Is provided. The take-out member 37 has a flange 38 at the lower peripheral edge and a lead-out port 39 at the upper part. The flange 38 is attached to the outer peripheral surface of the throttle body 24,
The passage 31 is connected to the outlet port 39. The outlet port 39 communicates the assist air introduced from the internal passage 25 into the extraction member 37 through the outlet holes 36 to the passage 3.
Derived within 1.

The operation and effect of the embodiment constructed as described above will be described. FIG. 7 shows the throttle valve opening T when the pressure difference between the upstream side and the downstream side of the throttle valve 26 is maintained at a constant value.
The relationship between A and the assist air amount Q1 is shown. The solid line in the figure shows the relationship between both parameters TA and Q1 in the present embodiment, and the two-dot chain line shows the relationship between both parameters TA and Q1 in the first embodiment as a comparative example.

As shown in the drawing, when the opening degree TA is in the range of 0 to θ1, the assist air amount Q1 is “0” in both the present embodiment and the comparative example. Then, as the opening degree TA increases to θ1 or more, the assist air amount Q1 increases in both the present embodiment and the comparative example. Here, it can be seen that the rate of change of the assist air amount Q1 (slope of the graph) in the present embodiment is larger than that in the comparative example. This is because, by arranging the outlet holes 36 in a line along the circumferential direction of the throttle body 24, the effective opening area (the area of each outlet hole 36 located in the atmospheric pressure region) can be reduced by opening the throttle valve 26. This is because it can be greatly increased according to the operation. And the opening degree T
When A becomes θ2, as shown in FIG. 7, the maximum value Q12 of the assist air amount Q1 in the present embodiment is larger than the maximum value Q11 of the assist air amount Q1 in the comparative example. This is because the formation of the plurality of outlet holes 36 in the throttle body 24 increases the effective opening area of the outlet hole 36.

Here, as a method for increasing the effective opening area of the entire outlet hole 36, besides the method of forming a plurality of outlet holes 36 as in this embodiment, for example, the diameter of the outlet hole 36 is increased. It is conceivable to increase the opening area. FIG. 11 shows the flow of intake air when such a configuration is employed. When the opening area of the outlet hole 36 is increased, the amount of air flowing downstream of the throttle valve 26 increases so as to bypass the peripheral edge of the throttle valve 26 as indicated by the arrow in FIG. That is, if the opening area of the outlet hole 36 is small, the air to be introduced into the hole will flow downstream of the throttle valve 26 if the opening area of the outlet hole 36 is increased. For this reason, in the above configuration example, the assist air amount Q1 cannot be efficiently increased.

On the other hand, in the present embodiment, the outlet hole 36 is provided.
Instead of increasing the opening area of the
Is formed on the throttle body 24. As a result, the effective opening area of the entire outlet hole 36 can be increased, and the air as described above is supplied to the throttle valve 2.
Thus, the assist air amount Q1 can be surely increased while avoiding the phenomenon of bypassing and passing around the peripheral edge of No. 6.
In particular, in the present embodiment, since the diameter of each of the outlet holes 36 is set to “2 mm”, it is possible to more reliably suppress the phenomenon that air bypasses the peripheral portion of the throttle valve 26 and passes therethrough. it can. In addition, from the viewpoint of avoiding the above-described air bypass phenomenon, the diameter of the outlet hole 36 is set to “3”.
mm "or less.

[Third Embodiment] Next, a third embodiment which embodies the second invention will be described focusing on differences from the second embodiment. Further, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the second embodiment, the plurality of outlet holes 3
6, the effective opening area is increased. In the present embodiment, as shown in FIG. 8, instead of the plurality of outlet holes 36, a slot 40 extending in the circumferential direction is formed in the throttle body 24. Is formed.

According to the present embodiment, substantially the same effects as those of the second embodiment can be obtained. In particular, in the present embodiment, since the elongated holes 40 are formed in the throttle body 24 instead of the plurality of outlet holes 36, the effective opening area can be further increased and the assist air amount Q1 can be increased.

[Fourth Embodiment] Next, a fourth embodiment embodying the third invention will be described, focusing on differences from the second embodiment. Further, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 9, the throttle body 24
In the case where the throttle valve 26 is fully closed (the state shown by the broken line in the figure), a plurality (five) of outlet holes 36 are located downstream (right side in the figure) of the valve 26.
Are formed. Further, the throttle body 24 has
FIG. 10 in which another outlet hole 41 located on the upstream side (left side in FIG. 10) of the throttle valve 26 is formed is a case where the pressure difference between the upstream side and the downstream side of the throttle valve 26 is maintained at a constant value. The relationship between the throttle valve opening TA and the assist air amount Q1 is shown. The solid line in the figure shows the relationship between both parameters TA and Q1 in the present embodiment, and the two-dot chain line shows the relationship between both parameters TA and Q1 in the first embodiment as a comparative example. As shown in the drawing, when the opening degree TA is in the range of 0 to θ1, the assist air amount Q1 is “0” in the comparative example, whereas the assist air amount Q1 in the present embodiment is a constant value. It is Q11. This is the throttle valve 2
This is because the outlet hole 41 located upstream of the nozzle 6, that is, in the atmospheric pressure region, secures a constant assist air amount Q11 by the outlet hole 41.

As described above, according to the present embodiment, it is possible to ensure the minimum amount of assist air Q1 when the throttle valve 26 is fully closed. Therefore, by appropriately setting the area of the outlet hole 41 located in the atmospheric pressure region, the engine 11 can be operated during idling.
Required by the assist air can be secured.

The present invention can be embodied as another embodiment described below in addition to the above embodiments. According to this other embodiment, substantially the same operation and effect as those of the above embodiments can be obtained.

(1) In each of the above embodiments, the throttle valve 26 is driven by the stepping motor 27. On the other hand, the present invention may be embodied in a configuration in which the throttle valve 26 is drivingly connected to an accelerator pedal, and the opening degree of the throttle valve 26 is changed according to the depression amount of the pedal.

(2) In the second embodiment, the outlet holes 36 are arranged in a line along the circumferential direction of the throttle body 24. On the other hand, as shown in FIG. 12, the outlet holes 36 are arranged in a line along the longitudinal direction of the throttle body 24, or are arranged in an arc as shown in FIG. Is also good. As described above, by changing the arrangement of the outlet holes 36, the assist air amount Q with respect to the throttle valve opening degree TA is changed.
1, the rate of change can be adjusted. Similarly, the rate of change can be adjusted by making the shape or diameter of each outlet hole 36 different. Further, the number of the outlet holes 36 is not limited to the number (five) shown in the embodiment, but can be changed as appropriate.

(3) In the third embodiment, one slot 40 extending in the circumferential direction of the throttle body 24 is
Only one was provided. On the other hand, this long hole 40
May be employed in the longitudinal direction of the throttle body 24. Further, in addition to the elongated hole 40, a lead-out hole 41 located in the atmospheric pressure region may be further provided as in the fourth embodiment.

(4) In the fourth embodiment, only one outlet hole 41 located in the atmospheric pressure region is provided. On the other hand, the minimum amount of the assist air amount Q1 may be adjusted by forming a plurality of outlet holes 41.

The technical ideas that can be grasped from the above embodiments are described below together with the effects. (A) In the throttle body structure for a fuel injection type internal combustion engine according to claim 1, the opening degree of the throttle valve is controlled according to the operating state of the engine at least when the internal combustion engine is idling. The throttle body structure of a fuel injection type internal combustion engine, wherein the opening is provided at a position where the effective opening area is changed by a throttle valve when the internal combustion engine is idling.

According to the above configuration, during idling of the internal combustion engine, the amount of assist air can be changed according to the opening of the throttle valve. As a result, atomization of fuel can be promoted during idling, and combustion in the internal combustion engine can be stabilized.

[0055]

According to the first aspect of the present invention, the throttle body is provided with an opening for assist air introduction, which is connected to the upstream portion of the assist air passage and opens into the internal passage. The effective opening area is changed by the throttle valve. Therefore, unlike the case where the assist air amount is adjusted by providing a flow control valve in the assist air passage, for example, the opening degree of the throttle valve that reflects the operating state of the internal combustion engine can be adjusted without complicating the configuration. The assist air amount can be adjusted accordingly.

According to the second aspect of the present invention,
The opening on the throttle body side of the assist air passage is an elongated hole or a plurality of holes extending along the circumferential direction of the throttle body. Therefore, unlike the configuration in which the area of the opening is simply increased, it is possible to avoid a phenomenon in which air bypasses the peripheral portion of the throttle valve and passes as described above. Therefore, the assist air can be reliably introduced into the assist air passage to increase the assist air amount.

According to the third aspect of the present invention,
When the throttle valve is fully closed, a part of the opening of the assist air passage on the throttle body side is located upstream of the throttle valve. Therefore, even when the throttle valve is fully closed, assist air is introduced into the assist air passage from the opening located upstream of the throttle valve, and the minimum amount of assist air is ensured. As a result, the intake air required for the engine can be secured by the assist air when the opening of the throttle valve is small, such as during idling.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an engine and the like in a first embodiment.

FIG. 2 is a partial sectional view showing a throttle body.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is a diagram showing a relationship between a throttle valve opening and an engine intake air amount;

FIG. 5 is a sectional view showing a throttle body according to a second embodiment.

FIG. 6 is a sectional view taken along the line 6-6 in FIG. 5;

FIG. 7 is a diagram showing a relationship between a throttle valve opening and an assist air amount.

FIG. 8 is a sectional view corresponding to a section taken along line 6-6 of FIG. 5 and showing a long hole in the third embodiment.

FIG. 9 is a sectional view corresponding to a section taken along line 6-6 of FIG. 5 and illustrating lead-out holes and the like in a fourth embodiment.

FIG. 10 is a graph showing a relationship between a throttle valve opening and an assist air amount.

FIG. 11 is a partial sectional view showing a flow of air in a comparative example.

FIG. 12 is a cross-sectional view showing a lead-out hole and the like in another embodiment.

FIG. 13 is a sectional view showing a lead-out hole and the like in another embodiment.

FIG. 14 is a sectional view showing a throttle body structure according to a conventional technique.

[Explanation of symbols]

11: gasoline engine as internal combustion engine, 20: intake manifold, 21: fuel injection valve, 21a: nozzle tip, 23: surge tank, 24: throttle body (2
0, 23, 24), 26 ...
Throttle valve, 35: assist air passage, 36: outlet holes as a plurality of holes, 40: elongated holes, 41: outlet holes.

Claims (3)

[Claims] 1. An intake passage for introducing air into an internal combustion engine, a fuel injection valve for injecting and supplying fuel to the internal combustion engine, and an assist air passage using a part of the air in the intake passage as assist air. Air for facilitating atomization of fuel injected from the nozzle tip by discharging assist air from the vicinity of the nozzle tip of the fuel injection valve through the assist air passage into the intake passage. A throttle body structure of a fuel injection type internal combustion engine having an assist mechanism, wherein the throttle body has a cylindrical shape having an internal passage which forms a part of the intake passage; and the fuel injection valve in the internal passage. A throttle valve provided on a more upstream side for adjusting an amount of air introduced into the internal combustion engine; An opening for assist air introduction, which is connected to an upstream portion of a road and opens to the internal passage, is provided in the throttle body, and an effective opening area in the opening is changed by the throttle valve which changes its position according to an opening degree. A throttle body structure for a fuel injection type internal combustion engine, characterized in that: 2. The throttle body structure for a fuel injection type internal combustion engine according to claim 1, wherein said opening is a plurality of holes or a long hole extending along a circumferential direction of said throttle body. 3. The opening according to claim 1, wherein a part of the opening is located upstream of the throttle valve when the throttle valve is fully closed. Throttle body structure of fuel injection type internal combustion engine.