JP2009257216A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize uniform spray as an entire nozzle in a fuel injection valve including a nozzle body having a plurality of injection holes injecting fuel arranged upstream and downstream of fuel flow. <P>SOLUTION: An inlet diameter (taper ratio) of the injection hole 22 downstream of the fuel flow is set larger than an inlet diameter (taper rate) of the upstream injection hole to keep a flow rate coefficient of the downstream injection hole large. By taking such a nozzle structure, spray characteristics of the downstream injection hole 22 and spray characteristics of the upstream injection hole 21 can be uniformized and uniform spray as the nozzle whole body can be materialized, even if downstream injection hole inlet fuel pressure of the fuel flow in a fuel channel 20 is low. Consequently, good combustion condition can be maintained, and fuel economy and exhaust emission can be improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that injects fuel in an internal combustion engine (engine).

  In an internal combustion engine such as a diesel engine or an in-cylinder direct injection gasoline engine, a fuel injection valve (fuel injection nozzle) that injects fuel into the cylinder is used. A general fuel injection valve includes a nozzle body having an injection hole for injecting fuel, and a needle that is reciprocally disposed inside the nozzle body and intermittently injects fuel from the injection hole. (For example, see Patent Documents 1 and 2).

  In an in-cylinder injection type engine, atomization and penetration force (spray reach distance) of fuel spray injected from a fuel injection valve into a combustion chamber of the engine greatly affects engine output and exhaust gas. That is, when atomization of fuel spray is promoted and sufficient penetration force is obtained, the combustion state of the fuel becomes good, the fuel consumption (fuel consumption rate) is improved, and the exhaust emission can be reduced.

As a method of atomizing fuel spray in the fuel injection valve, there is a method of increasing the fuel injection pressure by reducing the diameter of the nozzle hole formed in the nozzle body. In this case, in order to secure the total fuel injection amount, for example, as shown in FIG. 5, a plurality of injection holes (tapered holes) 321... 321 are provided in the nozzle body 302 along the upstream and downstream directions of the fuel flow. Yes. In the fuel injection valve 301 shown in FIG. 5, the needle 303 is accommodated in the nozzle body 302 so as to be able to reciprocate. The reciprocation of the needle 303 causes the fuel to flow into the nozzle holes 321. Shut off (fuel injection / stop) is performed.
JP 2003-120472 A JP 2005-315136 A

  By the way, in the fuel injection valve, for example, as shown in FIG. 6, the fuel pressure at the injection hole becomes lower toward the downstream side of the fuel flow (from A to B in FIG. 5) in the fuel flow path in the nozzle body. As shown in FIG. 5, in the case of a fuel injection valve 301 having a structure in which nozzle holes 321 and 321 having the same specifications (the same inlet diameter and taper rate) are arranged in the nozzle body 302, the nozzle holes 321 on the downstream side of the fuel flow. Since the spray ejected from the nozzle tends to have a larger particle size and lower penetration force, the nozzle as a whole tends to be non-uniform spray, which may deteriorate the combustion state.

  The present invention has been made in view of such circumstances, and in a fuel injection valve having a nozzle body in which a plurality of injection holes are arranged along the upstream and downstream directions of fuel flow, uniform spraying is realized as a whole nozzle. An object is to provide a structure that can be used.

  The present invention is a fuel injection valve used for fuel injection of an internal combustion engine, and a nozzle body in which a plurality of injection holes for injecting fuel supplied through a fuel flow path are arranged in the upstream and downstream directions of the fuel flow, It is premised on a fuel injection valve that is disposed inside the nozzle body so as to be reciprocally movable and has a needle that blocks or opens between the fuel flow path and the injection hole. The inlet diameter of the nozzle hole on the downstream side of the fuel flow is set larger than the inlet diameter of the nozzle hole on the upstream side.

  As a specific configuration of the present invention, each of the upstream and downstream nozzle holes of the fuel flow is a tapered hole whose diameter decreases from the inlet toward the outlet, and the inlet diameter of the downstream nozzle hole of the fuel flow. Can be set larger than the inlet diameter of the upstream nozzle hole.

  As another configuration, the nozzle hole on the upstream side of the fuel flow is a straight hole having a constant diameter, and the nozzle hole on the downstream side is a tapered hole whose diameter is reduced from the inlet toward the outlet, and the downstream side A configuration in which the inlet diameter of the nozzle hole is set larger than the inlet diameter of the upstream nozzle hole can be given.

  According to the present invention, since the inlet diameter of the nozzle hole on the downstream side of the fuel flow is made larger than the inlet diameter of the nozzle hole on the upstream side, spraying of the entire nozzle can be made uniform. That is, even if the fuel pressure at the nozzle hole on the downstream side of the fuel flow in the nozzle body (fuel flow path) is low, the inlet diameter of the nozzle hole on the downstream side of the fuel flow is larger than the inlet diameter of the upstream nozzle hole. By setting and increasing the flow coefficient of the downstream nozzle hole, it is possible to align the injection characteristics of the downstream nozzle hole with the injection characteristics of the upstream nozzle hole, and achieve uniform spraying for the entire nozzle can do.

  According to the present invention, in a fuel injection valve having a nozzle body in which a plurality of injection holes for injecting fuel are arranged in the upstream and downstream directions of the fuel flow, the inlet diameter of the injection hole on the downstream side of the fuel flow is set to the injection hole on the upstream side. Therefore, uniform spraying can be realized for the entire nozzle. As a result, the combustion state can be improved, and fuel consumption and exhaust emission can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the present invention is a fuel injection valve that injects fuel into a cylinder of an internal combustion engine such as a diesel engine or an in-cylinder direct injection gasoline engine, and a plurality of injection holes are provided along the upstream and downstream directions of the fuel flow. A fuel injection valve provided with a nozzle body and a needle that is reciprocally movable inside the nozzle body and intermittently injects fuel from the nozzle hole. In this case, by setting the inlet diameter of the downstream nozzle hole larger than the inlet diameter of the upstream nozzle hole, the injection characteristic of the downstream nozzle hole and the injection characteristic of the upstream nozzle hole are obtained. There is a feature in aligning. A specific configuration (embodiment) of such a fuel injection valve will be described below.

Embodiment 1
FIG. 1 is a longitudinal cross-sectional view showing a main structure of an example of a fuel injection valve according to the present invention.

  The fuel injection valve 1 of this example is mounted corresponding to each cylinder of an internal combustion engine (hereinafter referred to as an engine) such as a diesel engine (not shown), and is pressurized and pressurized in a pressurizing chamber of a fuel pump (not shown). The high-pressure fuel is a fuel injection valve that directly injects the high-pressure fuel into the combustion chamber of each cylinder of the engine, and includes a nozzle body 2 and a needle 3 as shown in FIG.

  The nozzle body 2 is formed in a substantially hollow cylindrical shape with a bottom, and a needle 3 is accommodated in the approximate center of the nozzle body 2. A fuel flow path 20 is formed between the inner peripheral surface 2 a of the nozzle body 2 and the outer peripheral surface 3 a of the needle 3.

  The nozzle body 2 is provided with a plurality of injection holes 21 and 22 along the upstream and downstream directions of the fuel flow. The upstream nozzle holes 21 and the downstream nozzle holes 22 of the fuel flow are respectively disposed at a plurality of locations (for example, 8 to 10 locations) in the circumferential direction of the nozzle body 2. The details of the nozzle holes 21 and 22 will be described later.

  The needle 3 is a solid cylindrical member, and includes a columnar portion 31, a truncated cone portion 32, and a conical portion 33. The needle 3 is disposed in the nozzle body 2 so as to be movable in the axial direction, and is reciprocated by an actuator (not shown) (for example, a solenoid and a compression coil spring). When the needle 3 is moved away from the nozzle holes 21 and 22 by the actuator, the fuel flow path 20 and the nozzle holes 21 and 22 communicate with each other, and the fuel in the fuel flow path 20 flows into each nozzle hole 21. , 22 are injected. On the other hand, when the needle 3 moves in the direction approaching the nozzle holes 21 and 22, the tip end portion (conical truncated portion 32) of the needle 3 comes into contact with the inner peripheral surface 2 a (sheet portion) of the nozzle body 2. The passage between the passage 20 and the injection holes 21 and 22 is blocked, and fuel injection is stopped.

  Next, the nozzle holes 21 and 22 of the nozzle body 2 will be described.

  In this example, two types of nozzle holes 21 and nozzle holes 22 having different specifications are arranged in the nozzle body 2 along the upstream and downstream directions of the fuel flow. The upstream nozzle hole 21 and the downstream nozzle hole 22 are conical taper holes whose diameters gradually decrease from the inlets 21a and 22a toward the outlets 21b and 22b, respectively.

  The diameter of the outlet 21b of the upstream nozzle hole 21 and the diameter of the outlet 22b of the downstream nozzle hole 22 are the same (or substantially the same), but the diameter of the inlet 22a (inlet diameter) of the downstream nozzle hole 22 is the same. ) Is set larger than the diameter (inlet diameter) of the inlet 21a of the upstream nozzle hole 21. That is, the taper rate of the downstream nozzle hole 22 is set larger than the taper rate of the upstream nozzle hole 21, and the flow coefficient of the downstream nozzle hole 22 is greater than the flow coefficient of the upstream nozzle hole 21. Is also getting bigger.

  By adopting such a nozzle structure, for example, the fuel pressure distribution in the fuel flow path as shown in FIG. 6 is considered, and the inlet fuel pressure of the downstream nozzle hole 22 is lower than the upstream nozzle hole 21. By setting the flow coefficient (inlet diameter) of the downstream nozzle hole 22 to be larger than the flow coefficient of the upstream nozzle hole 21 so as to compensate for this, for example, as shown in the schematic diagram of FIG. The spray characteristics (atomization / penetration force) of the upstream nozzle hole 21 and the downstream nozzle hole 22 can be made uniform, and uniform spraying can be realized as a whole nozzle. As a result, the combustion state can be improved, and fuel consumption and exhaust emission can be improved.

Embodiment 2
FIG. 3 is a longitudinal sectional view showing the structure of the main part of another example of the fuel injection valve of the present invention.

  The fuel injection valve 101 of this example is provided with a bottomed, substantially hollow cylindrical nozzle body 102, and inside the nozzle body 102 so as to be capable of reciprocating along the axial direction, as in the above-described embodiment. A solid cylindrical needle 3 is provided, and a fuel flow path 120 is formed between the inner peripheral surface of the nozzle body 102 and the outer peripheral surface of the needle 3.

  Two types of nozzle holes 121 and nozzle holes 122 of different specifications are arranged in the nozzle body 102 along the upstream and downstream directions of the fuel flow.

  The nozzle hole 121 on the upstream side of the fuel flow is a straight hole, and the diameter of the inlet 121a and the diameter of the outlet 121b are the same. On the other hand, the downstream nozzle hole 122 is a conical taper hole whose diameter gradually decreases from the inlet 122a toward the outlet 122b. The diameter of the outlet 121b of the upstream nozzle hole 121 and the diameter of the outlet 122b of the downstream nozzle hole 122 are the same (or substantially the same), but the diameter of the inlet 122a (inlet diameter) of the downstream nozzle hole 122 is the same. ) Is set larger than the diameter (inlet diameter) of the inlet 121a of the upstream nozzle hole 121, and the flow coefficient of the downstream nozzle hole 122 is larger than the flow coefficient of the upstream nozzle hole 121. ing.

  Also in this example, taking into account the fuel pressure distribution in the fuel flow path as shown in FIG. 6, for example, the fuel pressure at the inlet of the downstream nozzle hole 122 becomes lower than the nozzle hole 121 at the upstream side of the fuel flow. In order to compensate, by setting the flow coefficient (inlet diameter) of the downstream nozzle hole 122 to be larger than the flow coefficient of the upstream nozzle hole 121, the upstream nozzle hole 121 and the downstream nozzle hole 122 The spray characteristics (atomization / penetration force) can be made uniform, and uniform spraying can be realized for the entire nozzle. As a result, the combustion state can be improved, and fuel consumption and exhaust emission can be improved.

Embodiment 3
FIG. 4 is a longitudinal sectional view showing the structure of the main part of another example of the fuel injection valve of the present invention.

  A fuel injection valve 201 in this example is provided with a bottomed, substantially hollow cylindrical nozzle body 202, and in the interior of the nozzle body 202 so as to be capable of reciprocating along the axial direction, as in the above-described embodiment. A solid cylindrical needle 3 is provided, and a fuel flow path 220 is formed between the inner peripheral surface of the nozzle body 202 and the outer peripheral surface of the needle 3.

  In the nozzle body 202, two types of nozzle holes 221 and nozzle holes 222 having different specifications are arranged along the upstream and downstream directions of the fuel flow.

  The nozzle hole 221 on the upstream side of the fuel flow is constituted by a tapered hole portion (chamfered portion) 221c on the inlet 221a side and a straight hole portion 221d on the outlet 221b side. The diameter of the tapered hole portion 221c is gradually reduced toward the straight hole portion 221d. Similarly, the downstream side injection hole 222 includes a tapered hole portion (chamfered portion) 222c on the inlet 222a side and a straight hole portion 222d on the outlet 222b side. The diameter of the tapered hole portion 222c is gradually reduced toward the straight hole portion 222d.

  The diameter of the straight hole 221d (exit 221b) of the upstream injection hole 221 is the same (or substantially the same) as the diameter of the straight hole 222d (exit 222b) of the downstream injection hole 222. The taper rate (chamfering depth) of the tapered hole portion 222c of the nozzle hole 222 is set larger than that of the upstream nozzle hole 221. That is, the diameter (inlet diameter) of the inlet 222 a of the downstream nozzle hole 222 is set larger than the diameter (inlet diameter) of the inlet 221 a of the upstream nozzle hole 221, and the flow rate of the downstream nozzle hole 222. The coefficient is larger than the flow coefficient of the upstream nozzle hole 221.

  Also in this example, taking into account the fuel pressure distribution in the fuel flow path as shown in FIG. 6, for example, the fuel pressure at the inlet of the downstream nozzle hole 222 becomes lower than the nozzle hole 221 at the upstream side of the fuel flow. In order to compensate, by setting the flow coefficient (inlet diameter) of the downstream nozzle hole 222 to be larger than the flow coefficient of the upstream nozzle hole 221, the upstream nozzle hole 221 and the downstream nozzle hole 222 The spray characteristics (atomization / penetration force) can be made uniform, and uniform spraying can be realized for the entire nozzle. As a result, the combustion state can be improved, and fuel consumption and exhaust emission can be improved.

  Here, in the above embodiment, the fuel injection valve having the nozzle body provided with two types of nozzle holes having different specifications along the fuel flow direction has been described. The present invention can also be applied to a fuel injection valve having a nozzle body provided with three or more types of injection holes having different specifications along the same. In this case, the inlet diameter of the uppermost nozzle hole in the fuel flow direction is minimized, and the inlet diameter (flow coefficient) of each nozzle hole downstream of the uppermost nozzle hole is reduced toward the downstream side in the fuel flow direction. By increasing the size sequentially, the spray characteristics of all the nozzle holes of the nozzle body may be made uniform.

  Note that the fuel injection valve of the present invention can be applied to a port injection type engine as well as a diesel engine or an in-cylinder direct injection type gasoline engine.

It is a longitudinal cross-sectional view which shows the principal part structure of an example of the fuel injection valve of this invention. It is a figure which shows typically the fuel spray state of the fuel injection valve of FIG. It is a longitudinal cross-sectional view which shows the principal part structure of the other example of the fuel injection valve of this invention. It is a longitudinal cross-sectional view which shows the principal part structure of another example of the fuel injection valve of this invention. It is a longitudinal cross-sectional view which shows the principal part structure of the conventional fuel injection valve. It is a figure which shows the fuel pressure distribution in the fuel flow path of a nozzle body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Nozzle body 2a Inner peripheral surface 20 Fuel flow path 21 Upstream injection hole 21a Inlet 21b Outlet 22 Downstream injection hole 22a Inlet 22b Outlet 3 Needle

Claims (3)

A fuel injection valve used for fuel injection of an internal combustion engine, wherein a plurality of nozzle holes for injecting fuel supplied through a fuel flow path are arranged in the upstream and downstream directions of the fuel flow, and the nozzle body In a fuel injection valve provided with a needle that is disposed so as to be reciprocally movable inside and that cuts off or opens between the fuel flow path and the injection hole.
A fuel injection valve, wherein an inlet diameter of a downstream nozzle hole of the fuel flow is larger than an inlet diameter of an upstream nozzle hole. The fuel injection valve according to claim 1, wherein
The upstream and downstream nozzle holes of the fuel flow are tapered holes each having a diameter that decreases from the inlet toward the outlet, and the inlet diameter of the downstream nozzle hole of the fuel flow is that of the upstream nozzle hole. A fuel injection valve characterized by being larger than the inlet diameter. The fuel injection valve according to claim 1, wherein
The upstream nozzle hole of the fuel flow is a straight hole having a constant diameter, and the downstream nozzle hole is a tapered hole whose diameter decreases from the inlet toward the outlet, and the inlet diameter of the downstream nozzle hole A fuel injection valve characterized in that is larger than the inlet diameter of the upstream injection hole.

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