JP2017180206A - Injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injector capable of effectively utilizing air in the vicinity of the front end of a valve body, in a simple construction.SOLUTION: An injector 1 includes a valve body 10 having a fuel passage 15 inside, and injection holes 11 provided at the front end of the valve body 10 for injecting fuel from the fuel passage 15 to the outside of the front end. It further includes communication holes 12 communicated with intermediates in the axial directions of the respective injection holes 11 through the front end at its positions apart from outlet side openings of the injection holes 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an injector that injects fuel into a combustion chamber of an internal combustion engine.

  As an internal combustion engine, a diesel engine is known in which air in a combustion chamber is compressed by a piston to a high temperature, and fuel is injected from an injector, whereby air and fuel are mixed and spontaneously ignited (compression ignition) in the combustion chamber. Yes. An injector for injecting fuel includes a cylindrical valve body having a fuel passage therein, and a needle valve disposed therein, and the fuel in the fuel passage is provided at the tip portion of the valve body. The injection hole which injects to the exterior of is formed (for example, refer patent document 1). In the injector having such a configuration, the needle valve moves backward (moves to the side opposite to the tip of the valve body), whereby fuel is injected from the injection hole.

  In a diesel engine, a combustion chamber is formed on the top surface by providing a recess on the top surface of the piston. Here, if the fuel is directly injected near the center of the recess that is close to the tip, the fuel may be liquefied and the fuel combustion efficiency may be reduced. Therefore, the injector of the diesel engine is configured to inject fuel in the circumferential direction of the combustion chamber by tilting the axis of the injection hole with respect to the axis of the valve body. By doing so, liquefaction of fuel in the combustion chamber is suppressed, fuel is dispersed throughout the combustion chamber, and air and fuel are quickly mixed in the combustion chamber.

  In the configuration in which fuel is injected in the circumferential direction of the combustion chamber, a vertical airflow is formed from the position of the injection hole toward the side wall of the recess and further toward the center from the outside on the bottom side of the recess. However, since the momentum of the airflow that circulates around the combustion chamber and reaches near the center of the recess is weakened, there is a risk that the air near the center of the recess, that is, near the tip of the valve body in the recess may not be sufficiently mixed with the fuel. is there. In order to solve this problem, in the configuration of Patent Document 1, an air injection hole is provided at the tip of the valve body in addition to the fuel injection hole, so that air flowing from the center of the recess to the outside is provided in the combustion chamber. The air near the center of the recess is effectively used.

JP-A-9-88610

  However, in the configuration of Patent Document 1, not only the fuel passage but also the air passage must be formed inside the valve body, and a mechanism such as a pump and a valve for adjusting the injection amount and timing of air is also provided. There is a need. Such a configuration is very complicated and the productivity of the injector including the cost is not good. In addition, there is a problem that an injector having a complicated configuration tends to break down.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an injector that can effectively use the air in the vicinity of the tip of the valve body with a simple configuration.

  An injector according to an aspect of the present invention includes a valve body having a fuel passage therein, and an injection hole that is provided at a tip portion of the valve body and injects fuel in the fuel passage to the outside of the tip portion. It is an injector, Comprising: The communicating hole connected to the intermediate part of the axial direction of the said injection hole from the position away from the exit side opening part of the said injection hole in the said front-end | tip part is provided.

  Since the injector is provided with a communication hole that communicates with the intermediate portion in the axial direction of the injection hole, when fuel is injected through the injection hole, the communication hole becomes negative pressure and the outside of the communication hole (injection hole). The air in the vicinity of the side opposite to the side connected to the axially intermediate portion is sucked into the injection hole. The air sucked into the injection hole is injected from the injection hole together with the fuel. That is, by opening the communication hole at a location where the air flow is poor in the vicinity of the tip of the injector (the tip of the valve body), the air near the tip can be used effectively. For example, in the case of the diesel engine described above, the air near the center of the recess can be used effectively by opening the communication hole toward the center of the recess formed on the top surface of the piston.

  In the injector, the air in the vicinity of the tip of the injector can be effectively used only by providing a communication hole that communicates with the axial intermediate portion of the injection hole. That is, in order to use the air in the vicinity of the tip portion, no additional configuration other than the communication hole is required, so that the configuration of the injector is simple and the productivity of the injector is high.

2 is a schematic configuration diagram around a combustion chamber of the internal combustion engine shown in Embodiment 1. FIG. FIG. 2 is a schematic longitudinal sectional view of a tip portion of an injector provided in the internal combustion engine shown in Embodiment 1.

  Hereinafter, an injector according to an embodiment of the present invention will be described with reference to the drawings.

<Embodiment 1>
Prior to description of the injector of the embodiment, a diesel engine (internal combustion engine) including the injector will be described with reference to FIG.

≪Internal combustion engine≫
The internal combustion engine 100 includes a piston 2, a cylinder liner 3 that reciprocates the piston 2 inside, and a cylinder head 4 that is disposed on the cylinder liner 3. A concave portion 20 is formed on the top surface of the piston 2, and the concave portion 20 constitutes a combustion chamber 9. The cylinder head 4 is provided with an intake port 6 and an exhaust port 7, and both ports 6 and 7 are connected to the inside of the cylinder liner 3. An intake hole which is an opening end of the intake port 6 on the cylinder liner 3 side is opened and closed by an intake valve 6b, and an exhaust hole which is an opening end of the exhaust port 7 on the cylinder liner 3 side is opened and closed by an exhaust valve 7b. The tip of the injector 1 that injects fuel into the combustion chamber 9 is exposed from the ceiling portion of the combustion chamber 9 of the internal combustion engine 100, that is, the roof surface of the cylinder head 4 that faces the combustion chamber 9.

≪Injector≫
The injector 1 includes a cylindrical valve body 10 having a fuel passage therein, and a needle valve (not shown) disposed therein, and the fuel in the fuel passage is placed at the tip of the valve body 10. A plurality of injection holes 11 are formed for injection to the outside of the tip portion. In the injector 1 having such a configuration, the needle valve moves backward (moves to the side opposite to the tip of the valve body 10), so that fuel is injected from the injection hole 11. The injector 1 is connected to a control unit (not shown) constituted by an engine control unit or the like, and the amount and time of fuel injection can be adjusted by advancing and retracting the needle valve according to a command from the control unit. The needle valve is advanced and retracted by a solenoid or a piezo element.

  In addition to the injection hole 11, the injector 1 of this example has a communication hole 12 (see FIG. 2) that communicates with an intermediate portion of the injection hole 11 in the axial direction. The relationship between the injection hole 11 and the communication hole 12 will be described with reference to a longitudinal sectional view of the distal end portion of the valve body 10 in FIG. In FIG. 2, a schematic view around the injection hole 11 viewed from the axial direction of the injection hole 11 is shown at a lower right position in the longitudinal sectional view.

  As shown in FIG. 2, the axis of the injection hole 11 is inclined with respect to the axis of the valve body 10. The injection hole 11 has a narrow diameter portion 1A connected to a fuel passage 15 formed inside the valve body 10, a large diameter portion 1B having a larger inner diameter than the small diameter portion 1A, and an annular lid fitted into the large diameter portion 1B. It is comprised with 19 through-hole parts 1C. The fuel in the fuel passage 15 is injected to the outside of the tip end portion of the valve body 10 through the small diameter portion 1A, the large diameter portion 1B, and the through hole portion 1C as indicated by the white arrow. Since the fuel diffuses in the radial direction in the process of moving from the small diameter portion 1A to the large diameter portion 1B, the inner diameter of the through hole portion 1C is reduced to a small diameter portion as shown in FIG. 2 in order to make the fuel injection smooth. It is preferable to make it larger than the inner diameter of 1A.

  The communication hole 12 provided in addition to the injection hole 11 is an intermediate part (this example) in the axial direction of the injection hole 11 from a position away from the outlet side opening part (opening end of the through hole part 1C) of the injection hole 11. Then, it communicates with the large-diameter portion 1B). By providing this communication hole 12, when fuel is injected in the direction of the white arrow through the injection hole 11, the communication hole 12 becomes negative pressure, and the outside of the communication hole 12 (the axial intermediate portion of the injection hole 11). The air in the vicinity (on the opposite side to the side connected to) is sucked into the injection hole 11 as shown by the thick arrow. The air sucked into the injection hole 11 is injected from the injection hole 11 together with the fuel. In this example, the open end of the communication hole 12 (the end opposite to the through-hole portion 1C) is disposed on the protruding end side of the tip of the valve body 10, and is near the center of the recess 20 (see FIG. 1). The air is sucked into the communication hole 12. This is because in the configuration of the internal combustion engine 100 of FIG. 1, the air flow in the vicinity of the center of the recess 20 facing the tip of the valve body 10 is deteriorated.

  The injection hole 11 and the communication hole 12 can be formed as follows, for example. First, a machining hole (a hole having the same diameter as that of the narrow diameter portion 1A) connected to the fuel passage 15 from the outside of the tip end portion of the valve body 10 is formed, and a counterboring process is performed with the axis of the machining hole as a rotation center. A diameter portion 1A and a large diameter portion 1B are formed. Next, a processing groove that gradually becomes deeper from the protruding end side of the tip end portion of the valve body 10 toward the large diameter portion 1B is formed. Finally, the annular lid 19 is press-fitted into the large diameter portion 1B. As a result, the injection hole 11 including the small diameter portion 1A, the large diameter portion 1B, and the through hole portion 1C is formed. Further, the communication hole 12 is formed by connecting the processed groove to the large diameter portion 1B. If the gap between the bottom of the large diameter portion 1B and the annular lid 19 is increased, the amount of air sucked from the communication hole 12 can be increased. That is, what is necessary is just to determine the magnitude | size of the clearance gap between the bottom part of the large diameter part 1B, and the cyclic | annular cover 19 by what extent the amount of air suction from the communicating hole 12 shall be. The depth of the large diameter portion 1B and the thickness of the annular lid 19 may be substantially the same, and the injection hole 11 may be formed by the small diameter portion 1A and the through hole portion 1C. In this case, the communication hole 12 is connected to the small diameter portion 1A.

≪Effect≫
In the injector 1 described above, the air in the vicinity of the tip end portion of the valve body 10 can be effectively used only by providing the communication hole 12 communicating with the intermediate portion (large diameter portion 1B) in the axial direction of the injection hole 11. In the injector 1, since the air near the tip of the valve body 10 is used, an additional configuration other than the communication hole 12, such as a valve or a pump, is not necessary, so that the configuration of the injector 1 is simple. The injector 1 having a simple configuration is excellent in productivity and hardly breaks down.

≪Modification≫
The communication hole 12 shown in FIG. 2 is not limited to a configuration that opens to the protruding end side of the distal end portion of the valve body 10, but sucks in air at a location where the air flow in the combustion chamber 9 (see FIG. 1) is bad. It should just be arranged. Further, a plurality of communication holes 12 may be provided for one injection hole 11.

  In addition, it can also be set as the injection hole 11 without the large diameter part 1B of FIG. For example, the injection hole 11 may be formed by drilling, and the communication hole 12 communicating from the position different from the outlet side opening of the injection hole 11 to the axial intermediate portion of the injection hole 11 may be formed by drilling. .

<Embodiment 2>
The injector 1 described in the first embodiment can also be used as an injector of a gasoline engine. For example, in the case of a port injection type in which gasoline is injected into the intake port, the injector may be disposed obliquely so that the tip of the injector faces the downstream side of the port. In that case, the tip of the injector exposed to the intake port becomes a wall that hinders the flow of air, and the air flow in the downstream portion of the vicinity of the tip of the injector becomes worse. Therefore, if a communication hole communicating with the downstream portion of the tip portion is provided in the injector, the air in the portion where the air flow is bad can be used effectively. In addition, the injector 1 of Embodiment 1 can also be used as an injector of a gasoline direct injection engine. Also in this case, it is preferable to arrange the opening of the communication hole so that air can be taken in from a location where the air flow is bad.

  The injector of the present invention can be suitably used as an injector for a diesel engine or a gasoline engine.

DESCRIPTION OF SYMBOLS 100 Internal combustion engine 1 Injector 10 Valve body 11 Injection hole 12 Communication hole 15 Fuel passage 19 Annular lid 1A Small diameter part 1B Large diameter part 1C Through-hole part 2 Piston 20 Concave part 3 Cylinder liner 4 Cylinder head 6 Intake port 6b Intake valve 7 Exhaust Port 7b Exhaust valve 9 Combustion chamber

Claims (1)

An injector comprising a valve body having a fuel passage therein, and an injection hole provided at a tip portion of the valve body for injecting fuel in the fuel passage to the outside of the tip portion,
An injector provided with a communication hole that communicates with a middle portion in the axial direction of the injection hole from a position away from the outlet side opening of the injection hole at the tip.

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