JP2009156129A - Injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit formation of deposit by reducing temperature of a plate 21 including injection hole 16 without increasing the number of part items in an injector injecting and supplying fuel to an engine. <P>SOLUTION: In this injector, area of a heat radiation surface exposed to fuel in a fuel channel 15 when a needle valve 7 is seated on a plate 21 in a surface of the plate is larger than that of a heat receiving surface exposed to combustion gas in the surface of the plate 21. Consequently, heat balance at the plate 21 is set to keep quantity of heat received by the plate 21 less and to keep quantity of heat radiated from the plate 21 more, temperature of the plate 21 can be reduced. Consequently, temperature of the plate 21 can be reduced without increasing the number of part items, formation of deposit on the surface of the plate can be inhibited. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, in an injector, technical studies have been made from various viewpoints regarding removal or suppression of deposits generated by carbonization of residual fuel adhering to the periphery of an injection hole after injection by combustion gas. And as one of the technical examination with respect to such a deposit, the technique which suppresses generation | occurrence | production of a deposit by reducing the body temperature around a nozzle hole is considered.

For example, a technique is known in which the body around the nozzle hole is prevented from being directly exposed to combustion gas by covering the body around the nozzle hole with a seal member having an S-shaped cross section or a seal member called a plug. (For example, see Patent Documents 1 and 2).
However, in any technique, it is necessary to additionally provide a separate sealing member, and the number of parts increases.
JP 2000-170628 A JP 2006-83799 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the body temperature around the injection hole without increasing the number of parts in an injector for injecting and supplying fuel to the engine. The purpose is to suppress the generation of deposits.

[Means of Claim 1]
The injector according to claim 1 is a substantially cylindrical valve body, is accommodated on the inner peripheral side of the valve body, moves in the axial direction, and has a fuel between the inner peripheral surface of the valve body and its outer peripheral surface. A needle valve that forms a flow path, and a plate that has an injection hole for fuel and seals the space on the inner peripheral side of the valve body on the tip side. Is opened and closed with respect to the nozzle hole to start or stop fuel injection. The plate also releases heat received from the fuel combustion gas to the fuel in the fuel flow path. Of the surface of the plate, the heat radiating surface exposed to the fuel in the fuel flow path when the needle valve is seated on the plate is larger in area than the heat receiving surface exposed to the combustion gas in the surface of the plate. Is big.

  As a result, the heat balance in the plate is set so that the amount of heat received by the plate is reduced and the amount of heat released from the plate is increased, so the plate temperature (that is, the body temperature around the nozzle hole) is lowered. be able to. For this reason, without increasing the number of parts, the body temperature around the nozzle hole can be lowered to suppress the occurrence of deposits.

[Means of claim 2]
According to the injector of the second aspect, the heat radiating surface is provided with a groove, and the groove has an enlarged area of the heat radiating surface.
This means shows one form for enlarging the area of the heat dissipation surface in the plate.

[Means of claim 3]
According to the injector of the third aspect, the groove is a swirl groove that swirls the fuel flow from the fuel flow path toward the nozzle hole.
Thereby, in the injector in which the area of the heat radiating surface is enlarged by the groove, the disturbance of the fuel flow flowing into the nozzle hole increases, so that atomization of the injected fuel is promoted. For this reason, the body temperature around the injection hole can be lowered to suppress the generation of deposits, and atomization of the injected fuel can be promoted.

[Means of claim 4]
According to the injector of the fourth aspect, fins are provided on the heat dissipation surface, and the area of the heat dissipation surface is expanded by the fins.
This means shows one form for enlarging the area of the heat dissipation surface in the plate.

  The injector of the best mode 1 is a substantially cylindrical valve body, is accommodated on the inner peripheral side of the valve body and moves in the axial direction, and the fuel flow between the inner peripheral surface of the valve body and its outer peripheral surface. A needle valve that forms a passage, and a plate that has a fuel injection hole and seals the space on the inner peripheral side of the valve body on the tip side. The fuel injection is started or stopped by opening and closing the nozzle hole. The plate also releases heat received from the fuel combustion gas to the fuel in the fuel flow path. Of the surface of the plate, the heat radiating surface exposed to the fuel in the fuel flow path when the needle valve is seated on the plate is larger in area than the heat receiving surface exposed to the combustion gas in the surface of the plate. Is big.

According to the injector of the best mode 2, a groove is provided on the heat dissipation surface, and the area of the heat dissipation surface is expanded by the groove.
According to the injector of the best mode 3, the groove is a swirl groove that swirls the fuel flow from the fuel flow path toward the nozzle hole.
According to the injector of the best mode 4, fins are provided on the heat dissipation surface, and the area of the heat dissipation surface is expanded by the fins.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG.
For example, the injector 1 is mounted in a mounting hole 3 provided in an engine head 2 of a gasoline engine, and injects fuel directly into the combustion chamber 4 of each cylinder. The injector 1 receives fuel pressurized to a high pressure of 2 MPa, for example, and injects it into the combustion chamber 4 to form an air-fuel mixture. The air-fuel mixture formed in the combustion chamber 4 burns by spark discharge and generates an output.

  The injector 1 includes a nozzle section 6 that injects fuel, an electromagnetic solenoid section 8 that drives a valve body (needle valve 7) of the nozzle section 6, and a fuel receiving section 9 that receives high-pressure fuel. The fuel received through the portion 9 is guided to the distal end side through the fuel flow paths 11 to 15 formed therein, and is injected through the injection hole 16 by driving the needle valve 7.

  The nozzle portion 6 is accommodated in the substantially cylindrical valve body 19 and the inner circumferential space 20 of the valve body 19 and moves in the axial direction, and between the inner circumferential surface of the valve body 19 and its outer circumferential surface. A needle valve 7 that forms the fuel flow path 15 and a plate 21 that has an injection hole 16 and seals the inner circumferential side space 20 on the tip side. Then, when the needle valve 7 is attached to and detached from the plate 21, the fuel flow path 15 is opened and closed with respect to the injection hole 16, and fuel injection is started or stopped.

  The valve body 19 slidably supports the sliding shaft portion 23 of the needle valve 7, and a sliding contact surface 24 slidably contacting the inner peripheral surface of the valve body 19 is provided on the outer periphery of the sliding shaft portion 23. Flat surfaces 25 that do not slide in contact with the inner peripheral surface of the valve body 19 are alternately provided. A fuel passage is formed between the inner peripheral surface of the valve body 19 and the flat surface 25, and this fuel passage forms part of the fuel passage 15.

  Further, the plate 21 is provided with an annular and tapered seat surface 27, and the needle valve 7 is provided with an annular seat portion 28 that is separated from and in contact with the seat surface 27. Then, when the seat portion 28 comes in contact with the seat surface 27, the needle valve 7 is detached from the plate 21, and the fuel flow path 15 is opened and closed with respect to the injection hole 16.

  An annular sealing material 29 such as a Teflon (registered trademark) ring is attached to the outer periphery of the valve body 19 in order to maintain airtightness between the injector 1 and the engine head 2. And the sealing material 29 closes the clearance formed between the inner wall surface of the mounting hole 3 and the outer peripheral surface of the valve body 19 together with the airtight holding function, and suppresses the diffusion of the combustion gas, thereby reducing the combustion gas. It has the function of reducing the surface area of the exposed valve body 19.

  The electromagnetic solenoid unit 8 is formed with a solenoid coil 31 that is energized to generate a magnetic attractive force, a movable core 32 that is magnetically attracted backward by energization of the solenoid coil 31, and a predetermined gap formed on the rear end side of the movable core 32. The fixed core 33 that is fixed and magnetically attracts the movable core 32, and the movable core 32 is slidably supported and accommodated, and the core accommodating member 34 that fixes and accommodates the fixed core 33, and the movable core 32 is disposed first. A coil spring 35 serving as a restoring spring that urges the coil spring 35 and a gap adjusting member 36 that adjusts the gap between the movable core 32 and the fixed core 33 are provided.

  The solenoid coil 31 is provided by winding a large number of coil wires around a cylindrical resin bobbin 37 and is supplied with power from an in-vehicle power source (not shown) via a connector terminal 38.

  The movable core 32 is provided in a cylindrical body that is stepped down toward the front. The movable core 32 has a rear end portion slidably supported by the core housing member 34, and a front end portion sandwiches the rear end portion of the needle valve 7, thereby moving integrally with the needle valve 7 in the axial direction. .

  The outer peripheral surface of the movable core 32 forms the fuel flow path 14 together with the inner peripheral surface of the core housing member 34 and the rear outer peripheral surface of the needle valve 7. The fuel flow path 14 communicates with the fuel flow path 15 via the tip opening of the core housing member 34. The inner peripheral surface of the movable core 32 forms a fuel flow path 13, and the fuel flow path 13 communicates with the fuel flow path 14 through a through hole 39 that penetrates the movable core 32 in the radial direction.

The fixed core 33 is provided in a cylindrical shape, is fixed to the core housing member 34 on the outer peripheral side, and forms the fuel flow path 12 that houses the coil spring 35 and the gap adjusting member 36 on the inner peripheral side. The coil spring 35 is housed so that the front end is supported by the inner periphery of the movable core 32 and the rear end is supported by the gap adjusting member 36.
The gap adjusting member 36 adjusts the gap between the movable core 32 and the fixed core 33 to determine the lift amount of the needle valve 7 (that is, the amount of separation of the seat portion 28 from the seat surface 27 in the axial direction). Is.

  The fuel receiving section 9 has a fuel flow path 11 communicating with the fuel flow path 12, introduces fuel from the outside, and guides it to the fuel flow path 11 via the filter 41.

  With the above-described configuration, the injector 1 guides high-pressure fuel received from the outside to the nozzle hole 16 through the fuel flow paths 11 to 15 sequentially. The injector 1 energizes the solenoid coil 31 to drive the movable core 32 and the needle valve 7 rearward to separate the seat portion 28 from the seat surface 27, so that the fuel flow path 15 is directed to the nozzle hole 16. As a result, the fuel is injected into the combustion chamber 4 through the nozzle hole 16.

  In addition, when the energization of the solenoid coil 31 is stopped, the injector 1 drives the movable core 32 and the needle valve 7 forward by the urging force of the coil spring 35 so that the seat portion 28 is seated on the seat surface 27 and the fuel flow path. By closing 15 with respect to the nozzle hole 16, fuel injection is stopped.

And after the fuel flow path 15 is closed with respect to the nozzle hole 16 by the needle valve 7, 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 31 are performed according to commands from a predetermined electronic control device (ECU: not shown) mounted on the vehicle. Then, the ECU executes energization start and energization stop commands based on various detection values such as the engine speed and the accelerator opening.

[Features of Example 1]
The features of the injector 1 according to the first embodiment will be described with reference to FIG.
According to the injector 1, the plate 21 is provided in a dish shape with a flange. The rear end surface of the plate 21 is tapered from the above-described sheet surface 27, an annular annular plane 43 having the rear end edge of the sheet surface 27 as an inner peripheral edge, and from the outer peripheral edge of the annular flat surface 43 to the rear and outer peripheral sides. And a circular plane 45 with the leading edge of the sheet surface 27 as the outer peripheral edge.

  That is, the rear end surface of the plate 21 is continuously reduced in diameter toward the circular plane 45 at the front end with the annular plane 43 interposed therebetween. That is, the rear end surface of the plate 21 is reduced in diameter in a tapered shape with the annular plane 43 interposed therebetween.

Further, the outer peripheral surface of the plate 21 is reduced in a step shape toward the circular tip surface 47 exposed to the combustion chamber 4. That is, the outer peripheral surface of the plate 21 has a large-diameter outer peripheral surface 48 having the same diameter as the inner peripheral side space 20 of the valve body 19 and a small diameter provided on the distal end side of the large-diameter outer peripheral surface 48 smaller than the large-diameter outer peripheral surface 48. An outer peripheral surface 49 and an outer annular plane 50 provided in an annular shape between the large-diameter outer peripheral surface 48 and the small-diameter outer peripheral surface 49 are provided.
The nozzle hole 16 is provided so as to penetrate between the circular flat surface 45 and the tip surface 47, and forms a nozzle hole wall surface 51.

  As described above, the surface of the plate 21 is the circular plane 45, the seat surface 27, the annular plane 43, the tapered surface 44, the large-diameter outer peripheral surface 48, the outer annular plane 50, the small-diameter outer peripheral surface 49, the tip surface 47, and the nozzle hole wall surface. 51.

  When the position on the seat surface 27 on which the seat portion 28 is seated is defined as the seat position 54, the seat surface 27 on the rear end side and the outer peripheral side of the seat position 54 on the surface of the plate 21, an annular plane 43 and the tapered surface 44 form the fuel flow path 15 and are exposed to the fuel in the fuel flow path 15. Further, the seat surface 27, the circular plane 45, the nozzle hole wall surface 51, and the tip surface 47 on the front end side and the inner peripheral side with respect to the seat position 54 are exposed to the combustion gas along with the combustion of the fuel spray in the combustion chamber 4.

  Thereby, the plate 21 can release the heat received from the combustion gas to the fuel in the fuel flow path 15. That is, the seat surface 27, the annular flat surface 43, and the tapered surface 44 on the rear end side and the outer peripheral side from the seat position 54 are exposed to the fuel in the fuel flow path 15 to form a heat radiating surface. The side and inner peripheral sheet surface 27, the circular flat surface 45, the nozzle hole wall surface 51, and the tip surface 47 are exposed to combustion gas to form a heat receiving surface.

  The plate 21 is provided so that the heat dissipation surface has a larger area than the heat receiving surface. Here, the area of the heat receiving surface can be reduced, for example, by reducing the diameter of the tip surface 47 and reducing the inner peripheral diameter of the outer annular plane 50. That is, the outer annular flat surface 50 can be set so as not to be exposed to the combustion gas by being covered by the tip flange 56 of the valve body 19, so that the diameter of the tip surface 47 is reduced to the inner peripheral side and the tip flange 56 is By extending to the circumferential side, the area of the heat receiving surface can be reduced.

[Effect of Example 1]
According to the injector 1 of the first embodiment, the heat radiating surface exposed to the fuel in the fuel flow path 15 when the needle valve 7 is seated on the plate 21 is the surface of the plate 21. The area is larger than the heat receiving surface exposed to the combustion gas.
Thereby, since the heat balance in the plate 21 is set so that the amount of heat received by the plate 21 is reduced and the amount of heat released from the plate 21 is increased, the temperature of the plate 21 can be lowered. For this reason, since the temperature of the plate 21 can be lowered without increasing the number of parts, the occurrence of deposits on the surface of the plate 21 can be suppressed.

  According to the injector 1 of the second embodiment, as shown in FIG. 3, the groove 58 is provided in the tapered surface 44 and the annular flat surface 43, and the area of the heat radiating surface is expanded by the groove 58. The groove 58 is provided so as to be orthogonal to the annular plane 43.

According to the injector 1 of the third embodiment, as shown in FIG. 4, the groove 58 is a swirl groove for turning the fuel from the fuel flow path 15 toward the nozzle hole 16.
Thereby, in the injector 1 in which the area of the heat radiating surface is enlarged by the groove 58, the disturbance of the fuel flow flowing into the injection hole 16 increases, so that atomization of the injected fuel is promoted. For this reason, the temperature of the plate 21 can be lowered to suppress the generation of deposits, and atomization of the injected fuel can be promoted.

  According to the injector 1 of the fourth embodiment, as shown in FIG. 5, the rear end portion of the tapered surface 44 is cut and provided so as to be substantially parallel to the annular plane 43 and the outer annular plane 50. A plurality of fins 60 are concentrically provided on the surface. And by providing the fin 60, the area of the heat radiating surface is expanded.

  According to the injector 1 of the fifth embodiment, as shown in FIG. 6, the cylindrical portion 62 extends from the rear end edge of the tapered surface 44 to the rear end side. And the area of a heat radiating surface is expanded by providing the fin 60 cyclically | annularly in the internal peripheral surface of the cylindrical part 62. FIG.

[Modification]
According to the injectors 1 of the second and third embodiments, the area of the heat radiating surface is increased by providing the grooves 58 in the plate 21, and according to the injectors 1 of the fourth and fifth embodiments, the fins 60 are provided in the plate 21. Although the area of the heat radiating surface has been enlarged, both the groove 58 and the fin 60 may be provided in the plate 21 to enlarge the area of the heat radiating surface. In addition, the fins 60 may be provided on both the rear end surface of the tapered surface 44 and the inner peripheral surface of the cylindrical portion 62, and may be provided on other portions.

  Further, the injector 1 is attached to the engine head 2 of the gasoline engine and injects fuel directly into the combustion chamber 4. However, even if the injector 1 is attached to the intake pipe, it is the same as in the first to fifth embodiments. The effect of can be obtained. That is, when fuel is injected into the intake pipe to form an air-fuel mixture, the plate 21 may receive heat due to the internal EGR effect in which the combustion gas flows back to the intake pipe, and the heat received by the plate 21 due to such internal EGR effect. On the other hand, the injector 1 can effectively radiate heat from the plate 21.

Furthermore, even if the injector 1 is attached to a diesel engine, the same effects as in the first to fifth embodiments can be obtained.
Moreover, the shape of the plate 21 is not limited to the dish shape with a flange like Examples 1-5.

(A) is the whole block diagram of an injector, (b) is the principal part enlarged view of an injector (Example 1). (A) is a perspective view of a plate, (b) is sectional drawing which shows a thermal radiation surface and a heat receiving surface (Example 1). (A) is a perspective view of a plate, (b) is sectional drawing which shows a thermal radiation surface and a heat receiving surface (Example 2). (A) is a top view of a plate, (b) is sectional drawing which shows a thermal radiation surface and a heat receiving surface (Example 3). (A) is a perspective view of a plate, (b) is sectional drawing which shows a thermal radiation surface and a heat receiving surface (Example 4). (Example 5) which is sectional drawing which shows a thermal radiation surface and a heat receiving surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injector 7 Needle valve 15 Fuel flow path 16 Injection hole 19 Valve body 20 Inner peripheral side space (inner peripheral side space)
21 Plate 27 Sheet surface (heat radiating surface, heat receiving surface)
43 Annular plane (heat dissipation surface)
44 Tapered surface (heat dissipation surface)
45 Circular plane (heat receiving surface)
47 Tip surface (heat receiving surface)
51 Hole surface (heat receiving surface)
58 groove 60 fin

Claims (4)

A substantially cylindrical valve body;
A needle valve that is accommodated on the inner peripheral side of the valve body and moves in the axial direction, and forms a fuel flow path between the inner peripheral surface of the valve body and its outer peripheral surface;
A plate having a fuel injection hole and sealing the space on the inner peripheral side of the valve body on the tip side;
In the injector for starting or stopping fuel injection by opening and closing the fuel flow path with respect to the injection hole by detaching the needle valve from the plate,
The plate releases heat received from fuel combustion gas to the fuel in the fuel flow path,
Of the surface of the plate, the heat radiating surface exposed to the fuel in the fuel flow path when the needle valve is seated on the plate is the heat receiving surface exposed to the combustion gas in the surface of the plate Injector characterized in that the area is larger than. The injector according to claim 1, wherein
The injector is characterized in that a groove is provided in the heat radiating surface, and an area of the heat radiating surface is expanded by the groove. Injector according to claim 2,
The injector is characterized in that the groove is a swirl groove for turning a fuel flow from the fuel flow path toward the nozzle hole. The injector according to claim 1, wherein
2. An injector according to claim 1, wherein a fin is provided on the heat radiating surface, and an area of the heat radiating surface is expanded by the fin.

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