JP5170059B2 - Injector - Google Patents

Description

  The present invention relates to an injector for injecting and supplying fuel to an engine.

  2. Description of the Related Art Conventionally, techniques for atomizing fuel spray injected by an injector to promote mixing of fuel and air have been studied from various aspects. As one of the methods for promoting such atomization of spray, it has been studied to form the fuel flow in the nozzle hole in a liquid film shape and to reduce the liquid film of the fuel flow.

  For example, according to the injector described in Patent Document 1, the tip of the valve body is formed by a plate having an injection hole, and a pin extending toward the plate is provided at the tip of the valve body. In addition, a seating surface that expands toward the rear end side is provided behind the pin, and the seating surface is linearly and annularly attached to and detached from the seating surface of the valve body, so that the nozzle hole is formed. Opened and closed with respect to the fuel flow path in the valve body.

  As a result, when the seating surface is separated from the seating surface and the fuel flows from the fuel flow path toward the nozzle hole, the fuel that has passed between the seating surface and the seating surface is pressed against the pin. It is collected and flows into the nozzle hole. For this reason, the fuel flow in the nozzle hole becomes a liquid film, and atomization of the spray is promoted.

Moreover, according to the injector described in Patent Document 2, the tip of the valve body is provided in a spherical shape, and the seating surface is also provided in a spherical shape. The spherical seating surface is linearly and annularly attached to and detached from the tapered seating surface, whereby the nozzle hole is opened and closed with respect to the fuel flow path in the valve body.
As a result, when the fuel flows from the fuel flow path toward the nozzle hole, the fuel that has passed between the seating surface and the seating surface is pressed against the inner peripheral portion of the inner wall surface of the nozzle hole. Aggregated. For this reason, the fuel flow in the nozzle hole becomes a liquid film, and atomization of the spray is promoted.

  However, the demand for atomization of spray is very high, and the demand for further thinning the fuel flow in the nozzle hole is very active. In this respect, the injectors described in Patent Documents 1 and 2 have only one aggregation, and the injector described in Patent Document 2 is a place where fuel is concentrated (the portion on the inner peripheral side of the inner wall surface of the injection hole). Both are considered to have a lot of room for further improvement.

Japanese Patent No. 2553120 Japanese Patent No. 4129018

  The present invention has been made to solve the above-described problems, and an object of the present invention is to further promote atomization of the spray by further thinning the fuel flow in the injection hole in the injector.

[Means of Claim 1]
The injector according to claim 1 is provided with a valve body having a nozzle hole at a tip and a valve body accommodated in the valve body, and by accommodating the valve body in the valve body, the outer periphery of the valve body and the valve body A fuel flow path is formed between the inner periphery and the valve body is moved in the axial direction inside the valve body to be attached to and detached from the valve body, thereby opening and closing the injection hole with respect to the fuel flow path.

In addition, a seating surface for detaching from the seating surface of the valve body is provided at the tip of the valve body, and the seating surface is segregated linearly and annularly with respect to the seating surface, so that the nozzle hole Is opened and closed with respect to the fuel flow path. Further, a guide surface that is steeper than the seating surface by an angle in a range larger than 0 ° and smaller than 90 ° is provided at the distal end portion of the valve body and continuously extends to the inner peripheral side. The inner circumferential portion of the inner wall surface of the nozzle hole is inclined toward the outer circumferential side with respect to the guide surface by an angle in a range larger than 0 ° and smaller than 90 °.
Further, the downstream end of the guide surface is on the outer peripheral side of the inner peripheral wall portion of the nozzle hole, and the connecting portion between the seating surface and the guide surface is directed from the upstream side to the downstream side. In order to make the gradient steep, it forms an R shape on the cross section including the axis of the valve body. Furthermore, the extended surface which extended the guide surface to the downstream side cross | intersects the part of the inner peripheral side within the inner wall face of a nozzle hole.

  As a result, when the seating surface is separated from the seating surface and fuel flows from the fuel flow path toward the nozzle hole, the fuel that has passed between the seating surface and the seating surface is pressed against the guide surface. Are collected and flow into the nozzle hole. Further, the fuel that has flowed into the nozzle hole is pressed against the inner peripheral side portion of the inner wall surface of the nozzle hole and further collected. For this reason, the fuel flow in the nozzle hole can be further thinned to further promote atomization of the spray.

  In addition, the atomization effect by aggregating twice in the guide surface and the inner peripheral side part of the nozzle hole is concentrated in the atomization effect by aggregating once in the guide surface and the inner peripheral side part of the nozzle hole. Therefore, the means of claim 1 is an extremely effective means in that the atomization of the fuel in the nozzle holes is made thin to promote atomization of the spray.

In addition, by arranging the downstream end of the guide surface on the outer peripheral side of the inner peripheral side of the inner surface of the nozzle hole, the inner peripheral side portion of the nozzle hole, which is the second aggregation location, is provided. The directivity of the fuel flow can be increased. For this reason, the fuel flow in the nozzle hole can be further thinned to promote atomization of the spray.

In addition, the connecting portion between the seating surface and the guide surface is formed in an R shape on the cross section including the axial center of the valve body so that the gradient becomes steep from the upstream side toward the downstream side, thereby passing through the guide surface. Since the pressure loss of the fuel at the time of carrying out can be reduced, the pressure loss accompanying the fuel concentration on the guide surface can be suppressed.

[Means of claim 2 ]
According to the injector of the second aspect, the guide surface has a conical diameter reduced from the upstream side toward the downstream side.
This means shows one mode of the guide surface.

It is a whole block diagram of an injector ( reference example ). It is explanatory drawing which shows arrangement | positioning of a nozzle hole ( reference example ). It is a principal part block diagram of an injector ( reference example ). (A) is a correlation diagram of a liquid film thickness and a spray particle diameter, (b) is explanatory drawing which shows thinning of a liquid film thickness ( reference example ). It is a principal part block diagram of an injector ( Example) . It is a principal part block diagram of an injector (modification).

Injector implementation form, and the valve body having a nozzle hole at the tip, and a valve body which is accommodated in the valve body, by housing the valve element in the valve body, the inner periphery of the outer peripheral and the valve body of the valve body The fuel passage is formed between the nozzle body and the valve body is moved in the axial direction inside the valve body to be attached to and detached from the valve body, thereby opening and closing the nozzle hole with respect to the fuel passage.

  In addition, a seating surface for detaching from the seating surface of the valve body is provided at the tip of the valve body, and the seating surface is segregated linearly and annularly with respect to the seating surface, so that the nozzle hole Is opened and closed with respect to the fuel flow path. Further, a guide surface that is steeper than the seating surface by an angle in a range larger than 0 ° and smaller than 90 ° is provided at the distal end portion of the valve body and continuously extends to the inner peripheral side. The inner circumferential portion of the inner wall surface of the nozzle hole is inclined toward the outer circumferential side with respect to the guide surface by an angle in a range larger than 0 ° and smaller than 90 °.

Further, the downstream end of the guide surface is on the outer peripheral side of the inner peripheral wall portion of the nozzle hole, and the connecting portion between the seating surface and the guide surface is directed from the upstream side to the downstream side. In order to make the gradient steep, it forms an R shape on the cross section including the axis of the valve body. Furthermore, the extended surface which extended the guide surface to the downstream side cross | intersects the part of the inner peripheral side within the inner wall face of a nozzle hole. Note that the guide surface has a conical diameter decreasing from the upstream side toward the downstream side.

[Configuration of Reference Example ]
The structure of the injector 1 of a reference example is demonstrated using FIG.
The injector 1 is mounted on each cylinder of a gasoline engine (not shown), for example, and injects fuel directly into a combustion chamber (not shown). Further, the injector 1 forms a fuel spray by injecting, for example, a high-pressure fuel of 20 MPa into the combustion chamber. The fuel spray formed in the combustion chamber burns by spark discharge and generates an output.

  The injector 1 includes a nozzle portion 2 that injects fuel, an electromagnetic solenoid portion 4 that drives a valve body (needle valve 3) of the nozzle portion 2, and a fuel receiving portion 5 that receives high-pressure fuel. The fuel received through 5 is guided to the nozzle hole 14 through the fuel flow paths 7 to 12 formed therein, and is injected through the nozzle hole 14 by driving the needle valve 3.

  The nozzle portion 2 has a needle valve 3 that functions as a valve body, a nozzle hole 14 at the tip, and a cup-shaped needle support member 17 that houses the sliding shaft portion 16 of the needle valve 3 and supports it slidably. It has a nozzle body 18 that houses the needle valve 3 and the needle support member 17.

  Here, the needle support member 17 and the nozzle body 18 form a valve body that forms a substantially cylindrical internal space 19, and the needle valve 3 is accommodated in the internal space 19 and moves in the axial direction. The needle support member 17 and the nozzle body 18 accommodate the needle valve 3 in the internal space 19 so that the fuel flow path 12 toward the nozzle hole 14 is formed between each inner peripheral surface and the outer peripheral surface of the needle valve 3. , 11 are formed.

  The front end of the needle valve 3 is provided with a seating surface 22 for detaching from the seating surface 21 provided on the needle support member 17, and the seating surface 22 is linear with respect to the seating surface 21. The nozzle hole 14 is opened and closed with respect to the fuel flow path 12 by separating and attaching in an annular shape.

  Here, both the seating surface 21 and the seating surface 22 are provided in a tapered shape, and the seating surface 22 is an outer peripheral edge provided linearly and annularly (hereinafter, the outer peripheral edge is referred to as a seat portion 23). Is detached from and attached to the seating surface 21. When the seat portion 23 is detached from the seating surface 21, the nozzle hole 14 is opened and closed with respect to the fuel flow path 12, and fuel injection through the nozzle hole 14 is started or stopped.

  Note that, on the outer periphery of the sliding shaft portion 16, a sliding contact surface 24 that slides on the inner peripheral surface of the needle support member 17 and a flat surface 25 that does not slide on the inner peripheral surface of the needle support member 17 are alternately provided. ing. A fuel passage is formed between the inner peripheral surface of the needle support member 17 and the flat surface 25, and this fuel passage forms part of the fuel passage 12.

  The electromagnetic solenoid unit 4 includes a movable core 26 movable in the axial direction, a fixed core 28 that magnetically attracts the movable core 26 toward the rear end side in the axial direction by energizing the solenoid coil 27, and the movable core 26 at the distal end in the axial direction. A spring 29 that biases the spring 29, an adjuster 30 that sets the biasing force of the spring 29 against the movable core 26, and the like. The movable core 26, the fixed core 28, the spring 29, and the adjuster 30 are accommodated coaxially in the pipe 31. Yes.

  The solenoid coil 27 is provided by winding a coil wire around a cylindrical resin bobbin 34 many times, and is supplied with electric power from an in-vehicle power source (not shown) via a connector terminal 35. . The front end side, rear end side, and outer peripheral side of the solenoid coil 27 are covered with a yoke 36.

  The movable core 26 is provided as a cylindrical body that is stepped down toward the tip side. The movable core 26 is slidably supported by the pipe 31 at the rear end portion, and the front end portion sandwiches the rear end portion of the needle valve 3 so as to move integrally with the needle valve 3 in the axial direction. . The outer peripheral surface of the movable core 26 forms the fuel flow path 10 together with the inner peripheral surface of the pipe 31 and the outer peripheral surface of the rear end portion of the needle valve 3. The fuel flow path 10 communicates with the fuel flow path 11 through the opening at the tip of the pipe 31. Further, the inner peripheral surface of the movable core 26 forms a fuel flow path 9, and the fuel flow path 9 communicates with the fuel flow path 10 through a through hole 37 that penetrates the movable core 26 in the radial direction.

  The fixed core 28 is provided in a cylindrical shape and is fixed to the pipe 31 on the outer peripheral side, forms the fuel flow path 8 on the inner peripheral side, and accommodates the spring 29 and the adjuster 30 in the fuel flow path 8. The spring 29 has a support end that is supported by the adjuster 30 at the rear end, and a biasing end that supports the inner periphery of the movable core 26 and biases the movable core 26.

  The fuel receiving section 5 has a fuel flow path 7 that communicates with the fuel flow path 8, introduces fuel from the outside, guides it to the fuel flow path 7 through the filter 38, and further passes the fuel flow path 7 to the fuel flow path 7. Lead the fuel to 8.

With the configuration as described above, the high-pressure fuel received by the injector 1 sequentially passes through the fuel flow paths 7 to 12 and is guided to the injection hole 14.
In addition, among the forces to be considered regarding the opening and closing of the nozzle hole 14 in the balance of the axial force acting on the needle valve 3, the force acting in the valve closing direction is mainly a load due to fuel pressure (fuel pressure load). The biasing force (spring force) by the spring 29 and acting in the valve opening direction is mainly a suction force (electromagnetic suction force) that magnetically attracts the movable core 26 toward the rear end side in the axial direction by the fixed core 28. ).

  When the energization of the solenoid coil 27 is started and a magnetic circuit passing through the fixed core 28, the movable core 26 and the yoke 36 is formed and an electromagnetic attractive force is generated, the balance of the axial force acting on the needle valve 3 is Those acting in the valve opening direction are larger than those acting in the valve closing direction. For this reason, the movable core 26 and the needle valve 3 move toward the rear end side in the axial direction, the seating surface 22 is separated from the seating surface 21, and the injection hole 14 is opened to the fuel flow path 12. Through which fuel is injected.

Further, when the electromagnetic attraction force is not generated due to the energization stop of the solenoid coil 27, in the balance of the axial force acting on the needle valve 3, the one acting in the valve closing direction is more than the one acting in the valve opening direction. growing. For this reason, the movable core 26 and the needle valve 3 are moved to the front end side in the axial direction, the seating surface 22 is seated on the seating surface 21, the nozzle hole 14 is closed with respect to the fuel flow path 12, and the fuel injection is stopped. Is done.
The energization start and the energization stop of the solenoid coil 27 are performed according to commands from a predetermined electronic control device (ECU: not shown) mounted on the vehicle.

[Features of Reference Example ]
According to the injector 1 of the reference example , as shown in FIG. 2, a plurality of nozzle holes 14 are provided at equiangular intervals around the axis of the injector 1 at the tip of the needle support member 17. Each nozzle hole 14 is opened in an elliptical shape inside and outside the needle support member 17, and is provided so as to be inclined toward the outer peripheral side toward the tip and to increase in diameter.

  Further, as shown in FIG. 3, a guide surface 41 that is steeper than the seating surface 22 by an angle θ1 and extends continuously to the inner peripheral side is provided at the tip of the needle valve 3. Yes. Further, the inner peripheral side portion of the inner wall surface of the nozzle hole 14 (hereinafter referred to as the nozzle hole inner peripheral wall surface 42) is inclined toward the outer peripheral side with respect to the guide surface 41 by an angle θ2. . The angles θ1 and θ2 are both in the range larger than 0 ° and smaller than 90 °.

The downstream end of the guide surface 41 is on the outer peripheral side of the upstream end of the nozzle hole inner peripheral wall surface 42, and the extended surface extending the guide surface 41 downstream intersects the nozzle hole inner peripheral wall surface 42. ing. Further, the guide surface 41 has a conical diameter reduced from the upstream side toward the downstream side.
In addition, on the inner peripheral side of the seating surface 21, there is provided a relief tool relief space 45 when the seating surface 21 is polished and finished.

[Operation of Reference Example ]
The operation of the injector 1 of the reference example will be described with reference to FIG.
When the seating surface 22 is separated from the seating surface 21 and the injection hole 14 is opened to the fuel flow path 12, the fuel flows from the fuel flow path 12 toward the injection hole 14. At this time, the fuel that has passed between the seating surface 22 and the seating surface 21 is pressed against the guide surface 41 and is collected and flows into the nozzle hole 14. Further, the fuel that has flowed into the injection hole 14 is pressed against the inner peripheral side wall surface 42 of the injection hole and further collected. As a result, the fuel is formed into a thin film along the inner wall surface of the nozzle hole 14, and is jetted out of the nozzle hole 14 as a liquid film flow.

[Effects of Reference Example ]
According to the injector 1 of the reference example , the tip end portion of the needle valve 3 is steeper than the seating surface 22 by an angle θ1 in a range larger than 0 ° and smaller than 90 ° and continues to the seating surface 22. A guide surface 41 extending toward the inner peripheral side is provided, and the inner peripheral wall surface 42 of the nozzle hole is inclined toward the outer peripheral side with respect to the guide surface 41 by an angle θ2 in a range larger than 0 ° and smaller than 90 °. doing. Further, an extended surface extending the guide surface 41 downstream intersects the injection hole inner peripheral side wall surface 42.

  As a result, when the seating surface 22 is separated from the seating surface 21 and fuel flows from the fuel flow path 12 toward the nozzle hole 14, the fuel that has passed between the seating surface 22 and the seating surface 21. Are pressed against the guide surface 41 and gathered to flow into the nozzle hole 14. Further, the fuel that has flowed into the injection hole 14 is pressed against the inner peripheral side wall surface 42 of the injection hole and further collected. For this reason, the fuel flow in the nozzle hole 14 can be further thinned to further promote atomization of the spray.

  Here, in FIG. 4, when only the aggregation by the guide surface 41 (referred to as countermeasure A) is employed, when only the aggregation by the injection hole inner peripheral wall surface 42 (referred to as countermeasure B) is employed, countermeasures A and B are performed. The correlation between the fuel film thickness in the nozzle hole 14 and the spray particle size after injection is shown for the case where both are adopted and the case where both measures A and B are not adopted.

  Further, in FIG. 4, when both measures A and B are not adopted, only the measure A is adopted, only the measure B is adopted, and both measures A and B are adopted, the liquid film thickness. , D0, d1, d2 and d3, respectively, when both measures A and B are not adopted, only measure A is adopted, only measure B is adopted, and both measures A and B are adopted The spray particle diameter in the case of is shown as r0, r1, r2 and r3, respectively.

  According to FIG. 4, for both the liquid film thickness and the spray particle size, the reduction width when both measures A and B are adopted is the reduction width when only measure A is adopted, and only measure B is adopted. The reduction width is equal to or more than the sum of the reduction width in the case of the above. That is, (d0-d3) is larger than the sum of (d0-d1) and (d0-d2), and (r0-r3) is larger than the sum of (r0-r1) and (r0-r2). It is getting bigger.

  As described above, the atomization effect obtained by concentrating twice on the guide surface 41 and the nozzle hole inner peripheral wall surface 42 is equal to the atomization effect obtained by concentrating once on the guide surface 41 and the nozzle hole inner peripheral wall surface 42. It is an effect that is more than a simple addition to the atomization effect due to the re-aggregation, and the structure where the guide surface 41 and the inner peripheral wall surface 42 of the injection hole are aggregated twice causes the fuel flow in the injection hole 14 to be thinned and atomized fine particles. This is an extremely effective means in terms of promoting the conversion.

Further, the downstream end 43 of the guide surface 41 is located on the outer peripheral side of the upstream end 44 of the nozzle hole inner peripheral side wall surface 42.
Thereby, the directivity of the fuel flow to the inner peripheral wall surface 42 of the nozzle hole, which is the second gathering place, can be enhanced. For this reason, the fuel flow in the nozzle hole 14 can be further thinned to promote atomization of the spray.

( Example)
According to the injector 1 of the embodiment, as shown in FIG. 5, the connecting portion between the seating surface 22 and the guide surface 41 has an axis of the needle valve 3 so that the gradient becomes steep from the upstream side toward the downstream side. R shape is formed on the cross section including the core.
Thereby, since the pressure loss of the fuel at the time of passing through the guide surface 41 can be reduced, the pressure loss accompanying the concentration of the fuel on the guide surface 41 can be suppressed.

[Modification]
The aspect of the injector 1 is not limited to an Example, Various modifications can be considered. For example, according to the injector 1 of the embodiment, the nozzle hole 14 opens in a plane perpendicular to the axis of the needle valve 3 at the tip of the needle support member 17, but as shown in FIG. May be opened on an inclined surface similar to the seating surface 21. Further, the seating surface 22 of the needle valve 3 may be provided in a spherical shape, the tip of the valve body may be provided by a plate, the injection hole 14 may be provided so as to penetrate the plate, and the injector 1 is used as the intake manifold. It may be installed to inject fuel into the intake port.

1 Injector 3 Needle valve (valve)
12 Fuel flow path 14 Injection hole 17 Needle support member (valve body)
18 Nozzle body (valve body)
21 Seated surface 22 Seated surface 41 Guide surface 42 Inner peripheral side wall surface of injection hole (inner peripheral side portion of inner wall surface of injection hole)
43 Downstream end (downstream end of guide surface)
44 Upstream end (upstream end of the inner peripheral portion of the inner wall surface of the nozzle hole)
θ1, θ2 angle

Claims (2)

A valve body having a nozzle hole at a tip thereof; and a valve body accommodated in the valve body, and housing the valve body in the valve body, whereby an outer periphery of the valve body and an inner periphery of the valve body A fuel flow path between them,
In the injector that opens and closes the nozzle hole with respect to the fuel flow path by moving the valve body in the axial direction inside the valve body to be detached from the valve body,
The front end of the valve body is provided with a seating surface for detaching from the seating surface of the valve body, and the seating surface is segregated linearly and annularly with respect to the seating surface, The nozzle hole is opened and closed with respect to the fuel flow path;
Furthermore, a guide surface that is steeper than the seating surface by an angle in a range larger than 0 ° and smaller than 90 ° is extended to the inner peripheral side continuously from the seating surface at the tip of the valve body. Is provided,
The inner peripheral side portion of the inner wall surface of the nozzle hole is inclined toward the outer peripheral side with respect to the guide surface by an angle in a range larger than 0 ° and smaller than 90 °,
The downstream end of the guide surface is closer to the outer peripheral side than the upstream end of the inner peripheral side portion of the inner wall surface of the nozzle hole,
The connecting portion between the seating surface and the guide surface has an R shape on the cross section including the axial center of the valve body so that the gradient becomes steep from the upstream side toward the downstream side,
Furthermore, the extension surface which extended the said guide surface to the downstream side cross | intersects the part of the inner peripheral side within the inner wall face of the said injection hole, The injector characterized by the above-mentioned. The injector according to claim 1, wherein
The injector is characterized in that the guide surface has a conical diameter decreasing from the upstream side toward the downstream side .

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