JP2009167935A - Injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a deposit from accumulating on an wall surface of an injection hole 13, in an injector for injecting and supplying fuel. <P>SOLUTION: An injector includes an exothermic body 41 disposed facing the inside of an injection hole 13 for heating the wall surface of the injection hole 13. Thereby the deposit adhered to the wall surface of the injection hole 13 can be burnt out by being heated by the exothermic body 41. Thus, the deposit can be prevented from accumulating on the wall surface of the injection hole 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

Conventionally, an injector for injecting and supplying fuel to an engine has an injection hole at the tip, and is provided so as to inject fuel from the injection hole. For this reason, the residual fuel adhering to the wall surface of the nozzle hole is carbonized by the high-temperature combustion gas to form a deposit, which may prevent the fuel from being injected and change the injection characteristics. Therefore, a technique for forming an oil-repellent coating layer on the wall surface of the nozzle hole is known in order to promote the separation of deposits generated on the wall surface of the nozzle hole (see, for example, Patent Document 1). However, the peeling of the deposit is insufficient, and a separate countermeasure is required.
JP-A-9-112392

  The present invention has been made to solve the above-described problems, and an object thereof is to suppress deposits from being deposited on the wall surface of the injection hole in an injector for injecting and supplying fuel.

[Means of Claim 1]
The injector according to claim 1 is for injecting and supplying fuel to the engine, and is provided in a substantially cylindrical shape, and has a valve body in which a fuel injection hole is formed at the tip, and is accommodated in the valve body and is provided in the valve body. A fuel flow path is formed between the inner peripheral surface and its outer peripheral surface, and a needle valve that opens and closes the fuel flow path with respect to the nozzle hole, and a nozzle valve that faces the inside of the nozzle hole. And a heating element for heating the wall surface.
Thereby, the deposit adhering to the wall surface of the nozzle hole can be heated and burned off by the heating element. For this reason, it can suppress that a deposit accumulates on the wall surface of a nozzle hole.

[Means of claim 2]
According to a second aspect of the present invention, the injector includes a separate plate that is disposed on the distal end side of the valve body and holds the heating element. The nozzle hole has an upstream nozzle hole part provided in the valve body and a downstream nozzle hole part provided in a separate plate and communicating with the upstream nozzle hole part. It arrange | positions so that it may face the inside of a hole, and heats the wall surface of a downstream nozzle hole part.
The generation and adhesion of deposits is more remarkable at the downstream side of the nozzle hole. Therefore, by adopting a configuration in which the wall surface of the downstream nozzle hole part is heated by the heating element, deposit accumulation on the wall surface of the nozzle hole can be more efficiently suppressed.

[Means of claim 3]
According to the injector of the third aspect, the downstream nozzle hole part is larger in diameter than the upstream nozzle hole part.
This avoids the possibility that the downstream nozzle hole portion becomes a throttle for the fuel flow.

[Means of claim 4]
According to the injector of the fourth aspect, the heating element is provided in an annular shape, and forms all or part of the injection hole by its own inner peripheral surface.
This means shows an example of the arrangement of the heating elements.

  The injector of the best mode 1 is for injecting and supplying fuel to an engine, and is provided in a substantially cylindrical shape, and has a valve body in which a fuel injection hole is formed at the tip, and is accommodated in the valve body and is provided inside the valve body. A fuel flow path is formed between the peripheral surface and its own outer peripheral surface, and a needle valve that opens and closes the fuel flow path with respect to the injection hole, and a wall surface of the injection hole arranged so as to face the inside of the injection hole A heating element.

The injector includes a separate plate that is disposed on the distal end side of the valve body and holds the heating element. The nozzle hole has an upstream nozzle hole part provided in the valve body and a downstream nozzle hole part provided in a separate plate and communicating with the upstream nozzle hole part. It arrange | positions so that it may face the inside of a hole, and heats the wall surface of a downstream nozzle hole part.
Further, the downstream nozzle hole part is larger in diameter than the upstream nozzle hole part, and the heating element is provided in an annular shape, and forms all or part of the nozzle hole by its own inner peripheral surface.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG.
For example, the injector 1 is mounted on an engine head (not shown) of a gasoline engine, and injects fuel directly into a combustion chamber (not shown) of each cylinder. Further, the injector 1 receives fuel pressurized to a high pressure of 2 MPa, for example, and injects it into the combustion chamber to form an air-fuel mixture. The air-fuel mixture 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 the part 5 is guided to the distal end side through the fuel flow paths 8 to 12 formed therein, and is injected through the injection hole 13 by driving the needle valve 3.

  The nozzle portion 2 is provided in a substantially cylindrical shape, and has a valve body 16 in which a fuel injection hole 13 is formed at the tip, and is accommodated in the valve body 16 between the inner peripheral surface of the valve body 16 and its own outer peripheral surface. And the needle valve 3 forming the fuel flow path 12. Then, when the needle valve 3 is detached from the distal end portion 17 of the valve body 16, the fuel flow path 12 is opened and closed with respect to the injection hole 13, and fuel injection is started or stopped.

  Further, the valve body 16 slidably supports the sliding shaft portion 19 of the needle valve 3, and on the outer periphery of the sliding shaft portion 19, a sliding contact surface 20 slidably contacting the inner peripheral surface of the valve body 16, Flat surfaces 21 that do not slide in contact with the inner peripheral surface of the valve body 16 are alternately provided. A fuel passage is formed between the inner peripheral surface of the valve body 16 and the flat surface 21, and this fuel passage forms part of the fuel passage 12.

  Further, an annular and tapered seat surface 23 is provided at the distal end portion 17 of the valve body 16, and an annular seat portion 24 that is in contact with the seat surface 23 is provided at the distal end of the needle valve 3. Then, when the seat portion 24 comes in contact with and separates from the seat surface 23, the needle valve 3 is detached from the tip portion 17 and the fuel flow path 12 is opened and closed with respect to the injection hole 13.

  The electromagnetic solenoid unit 4 forms a predetermined gap at the rear end side of the movable core 27, the solenoid coil 26 that receives a current and generates a magnetic attractive force, the movable core 27 that is magnetically attracted backward by the current supplied to the solenoid coil 26. The fixed core 28 that magnetically attracts the movable core 27 and the movable core 27 is slidably supported and accommodated, and the core accommodating member 29 that fixes and accommodates the fixed core 28 and the movable core 27 A coil spring 30 serving as a restoring spring that biases the gap, and a gap adjusting member 31 that adjusts the gap between the movable core 27 and the fixed core 28.

  The solenoid coil 26 is provided by winding a large number of coil wires around a cylindrical resin bobbin 34, and is supplied with power from an in-vehicle power source (not shown) via a connector terminal 35 and a drive circuit 36.

  The movable core 27 is provided in a cylindrical body that is stepped down toward the front. The movable core 27 is slidably supported by the core housing member 29 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 27 forms the fuel flow path 11 together with the inner peripheral surface of the core housing member 29 and the rear outer peripheral surface of the needle valve 3. The fuel flow path 11 communicates with the fuel flow path 12 through the tip opening of the core housing member 29. Further, the inner peripheral surface of the movable core 27 forms a fuel flow path 10, and the fuel flow path 10 communicates with the fuel flow path 11 through a through hole 37 that penetrates the movable core 27 in the radial direction.

  The fixed core 28 is provided in a cylindrical shape, is fixed to the core housing member 29 on the outer peripheral side, and forms the fuel flow path 9 that houses the coil spring 30 and the gap adjusting member 31 on the inner peripheral side. The coil spring 30 is housed so that the front end is supported by the inner periphery of the movable core 27 and the rear end is supported by the gap adjusting member 31.

  The gap adjusting member 31 determines the lift amount of the needle valve 3 (the amount of separation in the axial direction of the seat portion 24 from the seat surface 23) by adjusting the gap between the movable core 27 and the fixed core 28. is there.

  The fuel receiving portion 5 has a fuel flow path 8 communicating with the fuel flow path 9, introduces fuel from the outside, and guides it to the fuel flow path 8 via the filter 39.

  With the above-described configuration, the injector 1 guides high-pressure fuel received from the outside to the injection hole 13 through the fuel flow paths 8 to 12 sequentially. The injector 1 then energizes the solenoid coil 26 to drive the movable core 27 and the needle valve 3 rearward to separate the seat portion 24 from the seat surface 23, so that the fuel flow path 12 is directed to the nozzle hole 13. By opening the nozzle, fuel is injected into the combustion chamber through the nozzle hole 13.

  In addition, when the energization of the solenoid coil 26 is stopped, the injector 1 drives the movable core 27 and the needle valve 3 forward by the biasing force of the coil spring 30 to seat the seat portion 24 on the seat surface 23, and thereby the fuel flow path. The fuel injection is stopped by closing 12 to the nozzle hole 13.

And after the fuel flow path 12 is closed with respect to the injection hole 13 by the needle valve 3, a fuel spray burns by spark discharge, an output is generated and a high-temperature combustion gas is generated.
The energization start and the energization stop of the solenoid coil 26 are performed by turning on and off the drive circuit 36 in response to a command from a predetermined electronic control device (ECU: not shown) mounted on the vehicle. The ECU calculates command values for the injection start timing (energization start timing) and the injection period (energization period) according to various detection values such as the engine speed and the accelerator opening, and based on these command values. The energization start and energization stop commands are executed.

[Features of Example 1]
The features of the injector 1 according to the first embodiment will be described with reference to FIGS.
The injector 1 includes a heating element 41 that heats the wall surface of the nozzle hole 13. The heating element 41 is, for example, a resistor that generates heat when energized, is provided with tungsten or the like as a material, and is held by a separate plate 42 that is separate from the valve body 16. The separate plate 42 is disposed on the distal end side of the distal end portion 17 of the valve body 16, holds the heating element 41 and forms a part of the injection hole 13.

  That is, the injection hole 13 is formed from an upstream injection hole part 44 provided in the tip part 17 of the valve body 16 and a downstream injection hole part 45 provided in the separate plate 42 and communicating with the upstream injection hole part 44. Thus, the heating element 41 is disposed so as to face the inside of the downstream injection hole 45 and heats the wall surface of the downstream injection hole 45. That is, the heating element 41 has an annular portion 47 provided in an annular shape, and the same number of annular portions 47 as the injection holes 13 are provided. The annular portion 47 is provided so as to be arranged in the same manner as the nozzle hole 13 and is held by the separate plate 42, and a part of the downstream nozzle hole portion 45 is formed by its own inner peripheral surface to be downstream. It faces the side nozzle hole 45.

  The downstream nozzle hole 45 is provided with a larger diameter than the upstream nozzle hole 44. Further, the upper and lower injection hole portions 44 and 45 are provided in a cylindrical shape, and the inner peripheral diameter of the annular portion 47 is set so as to substantially coincide with the hole diameter of the downstream injection hole portion 45.

  The separate plate 42 includes a main body 49 made of a ceramic material such as aluminum oxide or silicon nitride in consideration of heat resistance against high-temperature combustion gas and insulation against energization to the heating element 41. . The main body 49 is provided so that the downstream injection hole 45 passes therethrough, and the annular part 47 of the heating element 41 is held so as to face the downstream injection hole 45.

  Note that the wall surface of the downstream nozzle hole portion 45 is coated with a metal such as nickel or titanium to form the metal coating layer 50 including the surface portion constituted by the heat generating element 41. Thermal conductivity to the wall surface of the nozzle hole 13 is enhanced. The separate plate 42 and the valve body 16 are brazed with a metal such as silver or copper.

  The heating element 41 has a bridging portion 52 that bridges the annular portions 47 that are adjacent to each other in the circumferential direction, and each annular portion 47 is connected in series by the bridging portion 52. The plus end of the heating element 41 is connected to one end of the conducting wire 53, and the other end of the conducting wire 53 is connected to a connector terminal 54 that is different from the connector terminal 35.

  As a result, the heating element 41 is supplied with power from the in-vehicle power supply via the drive circuit 55 for energizing the heating element 41. Here, the portion of the conductive wire 53 that is disposed on the front end side is held by the insulating layer 56 made of glass, and the portion that is disposed on the rear end side is the connector portion 35 and 54 together with the connector portion. Is insulated and held by the resin constituting the, and is connected to the connector terminal 54. Further, the joint between the heating element 41 and the conductive wire 53 is sealed with an insulating layer 56.

  The energization of the heating element 41 is performed by turning on and off the drive circuit 55 in accordance with a command from the ECU. Here, the ECU determines whether to energize the heating element 41 based on the detected value of the air-fuel ratio of the exhaust gas (hereinafter referred to as A / F value) and the command value of the injection period ( (See FIG. 3). That is, the ECU stores a control flow related to energization control to the heating element 41 as shown in FIG. 3, and energizes the heating element 41 based on this control flow.

  This control flow is executed after combustion and exhaust of fuel in a specific cycle. First, in step S1, it is determined whether or not the A / F value is a predetermined value (for example, 14.6) or more. If (YES), the process ends, and if it is less than the predetermined value (NO), the process proceeds to step S2. Next, in step S2, it is determined whether or not the command value for the injection period is greater than or equal to a predetermined value. If it is greater than or equal to the predetermined value (YES), the process proceeds to step S3, and if it is less than the predetermined value (NO), the process ends. In step S3, the heating element 41 is energized.

In addition, the energization time to the heating element 41 is set to several seconds, for example, and the heating temperature of the heating element 41 is set to between 400 ° C. and 800 ° C., for example. The A / F value can be directly detected by an A / F sensor or can be calculated based on a detection value of an O ₂ sensor or the like. Further, the above control flow needs to be executed when the engine operating state is substantially the same, and is executed, for example, at idling after warm-up.

[Effect of Example 1]
The injector 1 according to the first embodiment includes a heating element 41 that is disposed so as to face the inside of the injection hole 13 and heats the wall surface of the injection hole 13.
Thereby, the deposit adhering to the wall surface of the nozzle hole 13 can be heated and burned off by the heating element 41. For this reason, it is possible to suppress deposits from being deposited on the wall surface of the nozzle hole 13.

Further, the heating element 41 is disposed so as to face the inside of the downstream nozzle hole 45 and heats the wall surface of the downstream nozzle hole 45.
The generation and adhesion of deposits is more remarkable at the downstream side of the nozzle hole 13. Therefore, by adopting a configuration in which the wall surface of the downstream nozzle hole 45 is heated by the heating element 41, deposit accumulation on the wall surface of the nozzle hole 13 can be more efficiently suppressed.

Further, the downstream nozzle hole part 45 is larger in diameter than the upstream nozzle hole part 44.
Thereby, it is possible to avoid the possibility that the downstream nozzle hole 45 becomes a throttle for the fuel flow.

  According to the injector 1 of the second embodiment, as shown in FIG. 4, the heating element 41 has an outer peripheral ring portion 59 that surrounds the main body 49, and the positive end and the negative end of the heating element 41 are located on the outer peripheral ring portion 59. Is provided. The outer peripheral ring portion 59 and the annular portion 47 are bridged by the bridge portion 52.

According to the injector 1 of the third embodiment, as shown in FIG. 5, the heating elements 41 are provided independently for each nozzle hole 13, and each heating element 41 includes an annular portion 47, a plus end, and a minus end. Have Further, all the annular portions 47 are insulated from each other and held by the main body portion 49. The drive circuit 55 is provided in the same number as the annular portion 47 so that all the annular portions 47 can be individually energized.
Thereby, according to the deposit accumulation dispersion | variation between the nozzle holes 13, it can energize separately to the annular part 47, or can change the resistance value of the annular part 47 for every nozzle hole 13, and can vary the emitted-heat amount. .

  According to the injector 1 of the fourth embodiment, as shown in FIG. 6, the injection hole 13 is provided only at the distal end portion 17 of the valve body 16, and the heating element 41 is arranged inside the injection hole 13.

[Modification]
Although the upper and downstream nozzle holes 44 and 45 of Examples 1 to 3 are provided in a cylindrical shape, one or both of the upper and downstream nozzle holes 44 and 45 are provided in a polygonal cylindrical shape. Also good. Moreover, you may provide the downstream nozzle hole part 45 in the taper shape which expands toward downstream. Similarly, the nozzle hole 13 of the fourth embodiment may be provided in a polygonal cylindrical shape, or may be provided in a tapered shape whose diameter increases toward the downstream side.

  In addition, the upstream injection hole 44 of the first to third embodiments is provided at the tip 17 of the valve body 16, but the upstream injection hole 44 is provided on a plate separate from the valve body 16. A separate plate 42 may be arranged on the tip side of the plate. Similarly, the nozzle hole 13 of the fourth embodiment may be provided on a plate separate from the valve body 16.

  Various modifications can be considered for energization control to the heating element 41. For example, a target value in the same operating state of the engine with respect to the A / F value and the injection period command value may be set, and the energization to the heating element 41 may be feedback controlled according to the deviation from the target value. For example, the energization to the heating element 41 may be feedback controlled so that the deviation converges to zero by manipulating the energizing time to the heating element 41 and the heating temperature of the heating element 41. Furthermore, the command value for the injection start time (energization start time) may be used together with the command value for the injection period as a criterion for determining whether or not the heating element 41 is energized. Further, instead of the command value for the injection period, only the command value for the injection start timing (energization start timing) may be used as a criterion for determining whether or not the heating element 41 is energized.

  Further, according to the control flow of the first embodiment, the heating element 41 is energized when the A / F value is equal to or greater than the predetermined value (14.6) and the command value for the injection period is equal to or greater than the predetermined value. However, an allowable range is set for the A / F value and the injection period command value, and the heating element 41 is energized when the A / F value and the injection period command value are out of the allowable ranges. You may make it perform.

For example, the allowable range of the A / F value is set to a numerical range (14.4 to 14.8) of 14.6 ± 0.2, and the A / F value is set to a numerical range (14.4 to 14.8). When it is out of the range, the determination regarding the command value of the injection period may be executed.
In addition, also when performing the determination regarding the A / F value and the command value of the injection period with respect to the allowable range, the energization to the heating element 41 can be feedback-controlled.

  The injector 1 of the embodiment is attached to the engine head of a gasoline engine and injects fuel directly into the combustion chamber. However, the injector 1 attached to the intake pipe or the exhaust pipe is similar to the embodiment. By adopting the configuration, it is possible to obtain the same effect as the embodiment.

In particular, in the case of an injector attached to the intake pipe, deposits are likely to occur on the wall surface of the injection hole 13 due to the internal EGR effect in which combustion gas flows back to the intake pipe. A configuration such as the injector 1 in the example can effectively suppress deposit accumulation.
Furthermore, even if the injector 1 is attached to a diesel engine, the same effect as in the embodiment can be obtained.

(A) is the whole block diagram of an injector, (b) is an enlarged view of the front-end | tip part of an injector (Example 1). (A) is explanatory drawing which shows a nozzle hole and a heat generating body by the cross section along the axial direction of an injector, (b) is explanatory drawing which shows a nozzle hole and a heat generating body by the cross section perpendicular | vertical to the axial direction of an injector (implementation) Example 1). 3 is a flowchart illustrating a control flow for controlling energization to a heating element (Example 1). (Example 2) which is a figure which shows a nozzle hole and a heat generating body by the cross section perpendicular | vertical to the axial direction of an injector. (Example 3) which is a figure which shows a nozzle hole and a heat generating body by the cross section perpendicular | vertical to the axial direction of an injector. (A) is explanatory drawing which shows a nozzle hole and a heat generating body by the cross section along the axial direction of an injector, (b) is explanatory drawing which shows the nozzle hole and heat generating body of an injector (Example 4).

Explanation of symbols

1 Injector 3 Needle valve 12 Fuel flow path 13 Injection hole 16 Valve body 41 Heating element 42 Separate plate 44 Upstream injection hole 45 Downstream injection hole

Claims (4)

In an injector that supplies fuel to an engine,
A valve body provided in a substantially cylindrical shape and having a fuel injection hole formed at the tip;
A needle valve that is accommodated in the valve body and forms a fuel flow path between an inner peripheral surface of the valve body and an outer peripheral surface of the valve body, and opens and closes the fuel flow path with respect to the nozzle hole;
An injector provided with a heating element arranged to face the inside of the nozzle hole and heating the wall surface of the nozzle hole. The injector according to claim 1, wherein
A separate plate that is disposed on the distal end side of the valve body and holds the heating element;
The nozzle hole has an upstream nozzle hole part provided in the valve body, and a downstream nozzle hole part provided in the separate plate and communicating with the upstream nozzle hole part,
The injector, wherein the heating element is disposed so as to face the inside of the downstream nozzle hole portion, and heats a wall surface of the downstream nozzle hole portion. Injector according to claim 2,
The downstream nozzle hole portion has a larger diameter than the upstream nozzle hole portion. In the injector according to any one of claims 1 to 3,
The said heat generating body is provided in cyclic | annular form, and forms the whole or one part of the said nozzle hole by the own internal peripheral surface, The injector characterized by the above-mentioned.

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