JP3744335B2 - Fuel supply device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply device for an internal combustion engine.
[0002]
[Prior art]
In an internal combustion engine, fuel is injected into an intake passage or a combustion chamber, mixed with intake air to form an air-fuel mixture, and this is ignited to obtain an output. At present, fuel injection is generally performed by an injector. A cross-sectional view of the tip of a conventional injector is shown in FIG. As shown in FIG. 6, the injector 101 has a slidable needle 103 inside the valve body 102. When the fuel is not injected, the needle 103 is pressed against the valve seat 110 formed with the injection hole 104 by the elastic restoring force of the spring 113, and the injection hole 104 is closed. At the time of injection, a magnetic force is generated by the solenoid coil 112 to separate the tip of the needle 103 from the valve seat 110 and inject fuel.
[0003]
Some injectors have a heater for the purpose of accelerating fuel atomization in order to improve startability at low temperatures and exhaust purification performance. As an injector having a heater, one described in Japanese Patent Application Laid-Open No. 5-143329 is known. The injector shown in FIG. 6 also has a heater 108 so that the fuel injected from the injection hole 104 through the inside of the needle 103 from the upper fuel passage 105 can be warmed by the heater 108. It is configured.
[0004]
[Problems to be solved by the invention]
However, in the conventional injector with a heater as described above, structural examination for efficiently heating the fuel has not been sufficient. For this reason, it has been impossible to sufficiently warm the fuel, or a large amount of electric power is required to drive the heater in order to sufficiently warm the fuel. Thus, there has been a demand for an improvement that can efficiently warm the fuel.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel supply device for an internal combustion engine capable of efficiently warming fuel and promoting atomization during fuel injection and improving startability and exhaust purification performance at low temperature start. It is in.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, in the fuel supply device for an internal combustion engine provided with an injector for injecting fuel into an intake passage or a combustion chamber of the internal combustion engine, the injector is slidable into the valve body and the inside of the valve body. A disposed needle, an injection hole that is opened and closed by the tip of the needle in accordance with the sliding of the needle, a first fuel passage formed on a proximal end extension of the needle, a first fuel passage, and an injection hole An annular second fuel passage formed around the needle between the first fuel passage and the second fuel passage, and at least one communication hole communicating the two passages; and the second fuel And a heater for heating the fuel in the second fuel passage, and the communication hole is formed so as to generate a swirling flow in the second fuel passage. Yes.
[0007]
Here, at least one communication hole, than the fuel supply upstream end of the heater, that have been further arranged on the fuel supply upstream.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
FIG. 1 shows a cross-sectional view of an injector in the first embodiment of the fuel injection device of the present invention. FIG. 1 shows a main part of the injector 1, and a valve body 2 and a heater 8 described later are covered from the outside by a case (not shown). The tip of the injector 1 is exposed in the intake passage and the combustion chamber.
[0010]
The injector 1 includes a valve body 2, a needle 3, an injection hole 4, a first fuel passage 5, a second fuel passage 6, a communication hole 7, a heater 8, an armature 9, a valve seat 10, a core 11, a solenoid coil 12, and A spring 13 is provided. A valve seat 10 is coupled to the tip of the valve body 2, and an injection hole 4 serving as an injection port for injecting fuel is formed in the valve seat 10. A space is formed inside the valve body 2, and the needle 3 is slidably disposed along the length direction thereof. In the present embodiment, the needle 3 is a hollow needle through which fuel can pass.
[0011]
The tip of the needle 3 is pressed against the valve seat 10 by the elastic restoring force of the spring 13, and the injection hole 4 is closed by this elastic restoring force when the fuel is not injected. The proximal end of the needle 3 is connected to the armature 9. A space is formed inside the armature 9, and one end of the spring 13 is in contact with the armature 9 in this space. The elastic restoring force of the spring 13 presses the needle 3 in the distal direction through the armature 9. A cylindrical core 11 is coupled to the armature 9 on the fuel supply upstream side (the side on which fuel is supplied) via a connecting member 14.
[0012]
A first fuel passage 5 is formed by the internal space of the core 11 and the internal space of the armature 9. The first fuel passage 5 is formed on the extension of the needle 3, and the above-described spring 13 is also disposed therein. The needle 3 described above is slidably disposed inside the valve body 2, and an annular second fuel passage 6 is formed between the valve body 2 and the needle 3. A heater 8 for warming the fuel in the second fuel passage 6 is attached to the outside of the second fuel passage 6. In the present embodiment, the heater 8 is attached to the outer surface of the valve body 2.
[0013]
The valve seat 10 has a space 17 formed therein, and the tip of the needle 3 projects into the space. The space 17 communicates with the nozzle hole 4 when the tip of the needle 3 is separated from the valve seat 10. A hole 15 is formed at the tip of the needle 3 so as to communicate the second fuel passage 6 and the internal space of the needle 3. Further, a hole 16 is also formed on the distal end side of the hole 15 so as to communicate the above-described space 17 and the internal space of the needle 3.
[0014]
A solenoid coil 12 for sliding the above-described core 11 is coupled to the proximal end side of the valve body 2. When a magnetic field is generated by the solenoid coil 12, the core 11 is slid by the magnetic force generated by the magnetic field. The core 11 is integrated with the armature 9 and the needle 3 via the connecting member 14, and the solenoid coil 12 is integrated with the valve body 2, the valve seat 10, and the like. For this reason, the tip of the needle 3 can be separated from the state pressed by the valve seat 10 by sliding the core 11 with the solenoid coil 12.
[0015]
Further, as shown in FIG. 2 which is a cross-sectional view taken along the line AA in FIGS. 1 and 1, the armature 9 is formed with a communication hole 7 that allows the first fuel passage 5 and the second fuel passage 6 to communicate with each other. In the present embodiment, two communication holes 7 are provided symmetrically with respect to the central axis of the needle 3, but at least one communication hole 7 may be provided. When the injection hole 4 is opened, the fuel is first fuel passage 5-communication hole 7-second fuel passage 6-hole 15-inner space of the needle 3-hole 16-space 17 in the valve seat 10-injection hole. The fuel is ejected by following the route 4.
[0016]
The communication hole 7 is formed to generate a swirling flow in the second fuel passage 6. The shape for forming the swirl flow will be described specifically by taking the case of this embodiment as an example. As shown in FIG. 7, the communication hole 7 is not formed radially from the central axis of the needle 3 in a cross section perpendicular to the central axis of the needle 3, and is formed offset with respect to the central axis. Has been. By doing so, a swirling flow can be generated in the second fuel passage 6. Alternatively, the swirl flow can be generated in the second fuel passage 6 by forming the communication holes 7 in a spiral shape radially outward from the first fuel passage 5 in the above-described cross section.
[0017]
The fuel is heated by the heater 8 while the swirling flow is generated in the second fuel passage 6 by the communication hole 7 described above, so that the boundary layer on the inner surface of the valve body 2 serving as a heat transfer portion of the heat from the heater 8 is formed. Disturbance can be given and heat transfer efficiency can be improved. In addition, since the fuel in the second fuel passage 6 forms a swirling flow, the chance of contact with the inner surface of the valve body 2 serving as a heat transfer portion of heat from the heater 8 is increased, so that more heat can be received. There is also an aspect that heat transfer efficiency is improved. As a result, the fuel can be efficiently warmed, which contributes to improvement of startability at the time of cold start and improvement of exhaust purification performance.
[0018]
Here, the first fuel passage 5 is formed on the proximal end side extension of the needle 3, the second fuel passage 6 is formed around the needle 3, and the second fuel is formed by the communication hole 7 that communicates both of them. A swirling flow is generated in the passage 6. Therefore, the performance can be improved with a simple structure without enlarging the injector 1. In order to give disturbance to the boundary layer described above, it is not necessary to provide a separate member such as a flow guide plate, which is convenient in terms of manufacturing cost and manufacturing method. Moreover, the simple structure mentioned above does not cause the mass increase of movable parts, such as the needle 3 and the armature 9. FIG. If the mass of the movable part increases, there is a risk of adversely affecting the opening / closing control of the nozzle hole 4 by the needle 3 (deterioration of high-speed followability, etc.), but this embodiment does not.
[0019]
Further, since warm the fuel in the second fuel passage 6 by the heater 8, the position of the communication hole 7, than the fuel supply upstream end of the heater 8, that have been further arranged on the fuel supply upstream. In other words, in FIG. 1, that is position communication hole 7 on the upper side than the upper end of the heater 8. If the communication hole 7 is plurality, at least one of which, Ru provided above position. By doing in this way, the swirl | flow is reliably formed in the heat transfer part of the heat | fever of the heater 8, and heat transfer efficiency can be improved further.
[0020]
Next, a second embodiment of the present invention is shown in FIGS. 4 is a cross-sectional view taken along line BB in FIG. Moreover, in this embodiment, about the component equivalent or the same as 1st embodiment mentioned above, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted. Hereinafter, only portions different from the first embodiment described above will be described in detail.
[0021]
The injector 1 in the present embodiment is different from that in the first embodiment described above in the configuration near the first fuel passage 5, the communication hole 7, and the valve seat 10. The first fuel passage 5 is formed on the proximal end side extension of the needle 3, but in the present embodiment, this communicates with the internal space of the needle 3. The communication hole 7 is formed on the proximal end side of the needle 3. However, also in this embodiment, the position of the communication hole 7 is located further on the fuel supply upstream side (upper side in FIG. 3) than the fuel supply upstream end of the heater 8.
[0022]
The nozzle hole 4 is opened and closed at the tip of the needle 3 in the same manner as in the first embodiment described above, but the space 17 inside the valve seat 10 is always in the second fuel passage 6 via the hole 18. Communicated with. For this reason, in this embodiment, when the nozzle hole 4 is opened, the fuel is supplied to the first fuel passage 5 (extending to the inner space of the needle 3) -communication hole 7-second fuel passage 6-. Injection is performed by following the path of the hole 18-the space 17 in the valve seat 10-the injection hole 4.
[0023]
As shown in FIG. 4, the communication hole 7 of the present embodiment is also formed so as to generate a swirling flow in the second fuel passage 6. Specifically, also in the present embodiment, the communication holes 7 are formed radially from the central axis of the needle 3 in a cross section perpendicular to the central axis of the needle 3 as in the first embodiment described above. Instead, it is offset from the central axis. Also in the present embodiment, the fuel is warmed by the heater 8 while generating a swirling flow in the second fuel passage 6 by the communication hole 7, so that the heat is transferred from the heater 8 on the inner surface of the valve body 2. The disturbance can be given to the boundary layer, and the heat transfer efficiency can be improved.
[0024]
Moreover, it is the same as that of the above-mentioned first embodiment that heat transfer efficiency can be improved with a simple structure and good response. Furthermore, also in this embodiment, the position of the communication hole 7 is arranged further on the fuel supply upstream side than the fuel supply upstream end of the heater 8. Therefore, the heat transfer efficiency can be further improved.
[0025]
Furthermore, FIG. 5 shows a third embodiment of the present invention. 5 is exactly the same as FIG. 2 which is a cross-sectional view taken along the line AA in the first embodiment. Also in the present embodiment, the same or similar components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, only portions different from the first embodiment described above will be described in detail.
[0026]
In the injector 1 in this embodiment, the needle 3 is not a hollow needle but a solid needle. And the formation form of the 1st fuel channel | path 5 and the communicating hole 7 is the same as that of 1st embodiment, and the structure of the valve seat 10 is the same as that of the second embodiment. For the purpose of reducing the inertial mass of the movable part, the needle 3 in this embodiment may be a hollow needle (the internal space becomes a closed space).
[0027]
Similarly, the communication hole 7 is configured to form a swirling flow in the second fuel passage 6. Similarly, the position of the communication hole 7 is located further on the fuel supply upstream side (upper side in FIG. 5) than the fuel supply upstream end of the heater 8. In this embodiment, when the nozzle hole 4 is opened, the fuel is referred to as a first fuel passage 5-a communication hole 7-a second fuel passage 6-a hole 18-a space 17 in the valve seat 10-the nozzle hole 4. It is injected along the route.
[0028]
Also in the present embodiment, the fuel is warmed by the heater 8 while generating a swirling flow in the second fuel passage 6 by the communication hole 7, so that the heat is transferred from the heater 8 on the inner surface of the valve body 2. The disturbance can be given to the boundary layer, and the heat transfer efficiency can be improved. Further, the heat transfer efficiency can be improved with a simple structure and good response as in the above-described embodiment. Furthermore, also in this embodiment, the position of the communication hole 7 is arranged further on the fuel supply upstream side than the fuel supply upstream end of the heater 8. Therefore, the heat transfer efficiency can be further improved.
[0029]
In addition, this invention is not limited to embodiment mentioned above. For example, in the second embodiment described above, the communication hole 7 is provided only on the proximal end side of the needle 3, but in addition to this, a communication hole is also formed in the center portion of the needle 3 and the distal end portion of the needle 3. You may do it. At this time, the communication hole formed in the central portion of the needle 3 is formed so as to promote the swirl flow formed by the communication hole on the base end side. Moreover, you may form the communicating hole 7 like 1st embodiment in the armature 9 of 2nd embodiment mentioned above.
[0030]
【The invention's effect】
According to the first aspect of the present invention, the fuel in the second fuel passage is heated by the heater while the swirling flow is generated in the second fuel passage by the communication hole, so that the heat transfer portion of the heat from the heater is The boundary layer on the inner surface of the valve body can be disturbed, and the heat transfer efficiency can be improved. In addition, the heat transfer efficiency can be improved with a simple structure and good response.
[0031]
Further , since the position of the communication hole is arranged further on the fuel supply upstream side than the end of the fuel supply upstream of the heater, the swirl flow is reliably formed in the heat transfer portion of the heater heat. The heat transfer efficiency can be further improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an injector in a first embodiment of a fuel supply apparatus of the present invention.
2 is a cross-sectional view taken along line AA in FIG. 1 (FIG. 5).
FIG. 3 is a cross-sectional view of an injector in a second embodiment of the fuel supply apparatus of the present invention. It is.
4 is a cross-sectional view taken along line BB in FIG.
FIG. 5 is a cross-sectional view of an injector in the third embodiment of the fuel supply apparatus of the present invention.
FIG. 6 is a cross-sectional view of an injector in a conventional fuel supply apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Injector, 2 ... Valve body, 3 ... Needle, 4 ... Injection hole, 5 ... 1st fuel passage, 6 ... 2nd fuel passage, 7 ... Communication hole, 8 ... Heater, 9 ... Armature, 10 ... Valve seat, 11 ... core, 12 ... solenoid coil, 13 ... spring.

Claims (1)

In a fuel supply device for an internal combustion engine comprising an injector for injecting fuel into an intake passage or a combustion chamber of the internal combustion engine,
The injector is
A valve body;
A needle slidably disposed inside the valve body;
A nozzle hole that is opened and closed by the tip of the needle according to the slide of the needle,
A first fuel passage formed on a proximal end extension of the needle;
An annular second fuel passage formed around the needle between the first fuel passage and the nozzle hole;
At least one communication hole formed between the first fuel passage and the second fuel passage and communicating both passages;
A heater disposed outside the second fuel passage and for heating the fuel in the second fuel passage;
The communication hole is formed so as to generate a swirling flow in the second fuel passage, and at least one of the communication holes is arranged further on the fuel supply upstream side than the fuel supply upstream end of the heater. A fuel supply device for an internal combustion engine.

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