JP4670873B2 - Injector - Google Patents

Description

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

  Conventionally, in order to maintain airtightness between an injector and an attachment body such as an engine head, for example, a member such as a Teflon ring (Teflon is a registered trademark) is attached to the outer periphery and attached to the attachment body. ing. This Teflon ring (Teflon is a registered trademark) suppresses the diffusion of combustion gas by keeping the airtightness and closing the clearance formed between the inner wall surface of the injector mounting hole and the outer peripheral surface of the injector. Also, by reducing the surface area of the injector body exposed to the combustion gas, it has the effect of reducing the temperature around the injection hole at the tip of the injector and suppressing the generation of deposits.

  By the way, in order to increase such a temperature lowering effect, it is preferable to move the mounting position of the Teflon ring (Teflon is a registered trademark) to the tip side of the injector, but the Teflon ring becomes hot at the tip side. (Teflon is a registered trademark) is highly likely to melt. Therefore, apart from the mounting of the Teflon ring (Teflon is a registered trademark), the surface area of the body exposed to the combustion gas is greatly reduced by covering the tip of the body around the nozzle hole with a metal sealing material, that is, A technique for blocking combustion gas from diffusing deep into the clearance has been considered (see, for example, Patent Document 1).

However, in order to form a combustion gas blocking structure using such a sealing material, it is necessary to provide the sealing material in a complicated shape (for example, a cup shape having an S-shaped cross section). In addition, a separate process such as a wrinkle process is required, and the manufacturing becomes complicated. In addition, due to such a complicated structure, there is a high risk of damage to the surface of the mounted body when the sealing material is mounted, and airtightness is maintained by repeatedly removing and mounting the injector after repeated maintenance. There is a risk that the effect of blocking the combustion gas will be reduced.
JP 2000-170628 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a seal that forms a combustion gas blocking structure at the tip of a body around an injection hole in an injector for supplying fuel to an engine. With regard to the material, even if maintenance or the like is repeated, the effect of blocking the combustion gas is not lowered.

[Means of Claim 1]
The injector according to claim 1 is attached to a predetermined mounting hole and injects and supplies fuel to the engine, is provided in a substantially cylindrical shape, has a fuel injection hole at the tip, and an inner wall surface of the mounting hole. A valve body that forms a clearance between the valve body and the outer peripheral surface of the valve body, and a fuel flow path that is accommodated in the valve body and is formed between the inner peripheral surface of the valve body and the outer peripheral surface of the valve body. A needle valve that opens and closes to the nozzle hole, and an annular body that is annularly mounted on the outer periphery of the tip of the valve body, deforms toward the outer periphery when the engine starts and closes the clearance, and opens the clearance when the engine is stopped. Prepare.

  Thereby, since the outer periphery of the annular body when the engine is stopped forms a clearance with the inner wall surface of the mounting hole, there is a low possibility that the annular body damages the inner wall surface of the mounting hole when the injector is removed. Further, when the injector is mounted, there is a low possibility that the annular body damages the inner wall surface of the mounting hole. For this reason, even if maintenance or the like is repeated, the inner wall surface of the mounting hole is less likely to be damaged, so the effect of blocking the combustion gas by the annular body does not decrease.

According to the injector of the first aspect , the annular body is welded to the valve body to form an annular fuel chamber together with the valve body, and the fuel chamber communicates with the fuel flow path by the throttle penetrating the valve body. is doing. The annular body is deformed to the outer peripheral side by increasing the fuel pressure in the fuel flow path and the fuel chamber as the engine is started, and closes the clearance. When the engine is stopped, the fuel pressure in the fuel flow path and the fuel chamber is reduced. By reducing the pressure, it is deformed to the inner peripheral side to open the clearance.

  As a result, the fuel pressure in the fuel flow path and the fuel chamber increases with the start of the fuel supply device, and the clearance is closed. Therefore, before the first explosion after the engine is started (hereinafter referred to as the first explosion), A combustion gas blocking structure is formed at the tip of the valve body. For this reason, the combustion gas due to the first explosion can be reliably shut off in the injector in which the combustion gas shutoff effect does not decrease even if maintenance or the like is repeated. In addition, since the fuel chamber and the fuel flow path communicate with each other by a throttle, the influence of pressure pulsation in the fuel flow path on the fuel pressure in the fuel chamber is greatly reduced, and the annular body stably closes the clearance. The combustion gas blocking effect can be maintained.

[Means of claim 2 ]
According to the injector of the second aspect , the annular body is welded to the valve body so as to partially cover the distal end surface of the valve body where the injection hole is opened.
Thereby, while a cyclic | annular body interrupts | blocks combustion gas, itself receives heat directly from combustion gas in the front end side of a valve body. For this reason, since the amount of heat received from the combustion gas can be reduced at the tip surface of the valve body, the effect of lowering the temperature around the injection hole at the tip of the injector can be enhanced.

[Means of claim 3 ]
According to the injector of the third aspect , the annular body is provided by a metal material having higher elasticity than the valve body.
This means shows one form of the material forming the annular body. An example of such a highly elastic metal material is a titanium alloy .

  The injector of the best mode 1 is installed in a predetermined mounting hole and injects and supplies fuel to the engine, is provided in a substantially cylindrical shape, has a fuel injection hole at the tip, and an inner wall surface of the mounting hole. A valve body that forms a clearance between itself and an outer peripheral surface; a fuel flow path that is accommodated in the valve body and formed between the inner peripheral surface of the valve body and the outer peripheral surface of the valve body; A needle valve that opens and closes with respect to the hole, and an annular body that is annularly mounted on the outer periphery of the tip of the valve body, deforms toward the outer periphery as the engine starts and closes the clearance, and opens the clearance when the engine is stopped. .

The annular body is welded to the valve body to form an annular fuel chamber together with the valve body, and the fuel chamber communicates with the fuel flow path through a throttle that penetrates the valve body. The annular body is deformed to the outer peripheral side by increasing the fuel pressure in the fuel flow path and the fuel chamber as the engine is started, and closes the clearance. When the engine is stopped, the fuel pressure in the fuel flow path and the fuel chamber is reduced. By reducing the pressure, it is deformed to the inner peripheral side to open the clearance.
Further, the annular body is provided by a metal material having higher elasticity than the valve body.

According to the injector of the best mode 2, the annular body is welded to the valve body so as to partially cover the distal end surface of the valve body where the injection hole is opened .

[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 provided in a substantially cylindrical shape, has a fuel injection hole 16 at the tip, and forms a clearance 19 between the inner wall surface 18 of the mounting hole 3 and its outer peripheral surface, and a valve body The fuel flow path 15 is formed between the inner peripheral surface of the valve body 20 and the outer peripheral surface of the valve body 20, and the needle valve 7 that moves in the axial direction and is attached to and detached from the tip of the valve body 20. Prepare. When the needle valve 7 is detached from the tip of the valve body 20, the fuel flow path 15 is opened and closed with respect to the injection hole 16, and fuel injection is started or stopped.

  Further, the valve body 20 slidably supports the sliding shaft portion 22 of the needle valve 7, and on the outer periphery of the sliding shaft portion 22, a sliding contact surface 23 slidably contacting the inner peripheral surface of the valve body 20, and Flat surfaces 24 that do not slide on the inner peripheral surface of the valve body 20 are alternately provided. A fuel passage is formed between the inner peripheral surface of the valve body 20 and the flat surface 24, and this fuel passage forms part of the fuel passage 15.

  Further, an annular and tapered seat surface 26 is provided at the distal end of the valve body 20, and an annular seat portion 27 that is in contact with and separates from the seat surface 26 is provided at the distal end of the needle valve 7 (see FIG. 2). ). Then, when the seat portion 27 comes in contact with the seat surface 26, the needle valve 7 is detached from the tip of the valve body 20, and the fuel flow path 15 is opened and closed with respect to the injection hole 16.

  An annular Teflon ring 29 (Teflon is a registered trademark) is attached to the outer periphery of the valve body 20 in order to maintain airtightness between the injector 1 and the engine head 2. The Teflon ring 29 (Teflon is a registered trademark) has a function of reducing the surface area of the valve body 20 exposed to the combustion gas by closing the clearance 19 and suppressing the diffusion of the combustion gas, together with an airtight holding function. Have.

  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 spring, and a gap adjusting member 36 that adjusts the gap between the movable core 32 and the fixed core 33.

  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 27 from the seat surface 26 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 so that the seat portion 27 is separated from the seat surface 26, and 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.

  Further, 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 to seat the seat portion 27 on the seat surface 26, and thereby 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.
The injector 1 includes an annular body 43 that is annularly attached to the outer periphery of the valve body 20 on the tip side (that is, the combustion chamber 4 side) of the Teflon ring 29 (Teflon is a registered trademark). The annular body 43 opens the clearance 19 when the engine is stopped (see FIG. 2A), and is deformed to the outer peripheral side when the engine is started to close the clearance 19 (see FIG. 2B). When the engine is stopped, the annular body 43 is deformed to the inner peripheral side to open the clearance 19.

  That is, the annular body 43 is provided in a substantially cylindrical shape by a metal material having higher elasticity than the valve body 20 such as, for example, a titanium alloy, and circumferentially around the outer peripheral surface of the valve body 20 at its front and rear ends. An annular fuel chamber 47 is formed between the welded portion 45 at the front end and the welded portion 46 at the rear end. The fuel chamber 47 communicates with the fuel flow path 15 by a throttle 48 that penetrates the valve body 20.

  The annular body 43 is configured so that the fuel supply device (not shown) is activated when the engine is started and the fuel pressure in the fuel flow path 15 and the fuel chamber 47 is increased, so that the portion between the welded portions 45 and 46 is the outer periphery. The clearance 19 is closed by elastic deformation. Further, the annular body 43 is elastically deformed between the welded portions 45 and 46 to the inner peripheral side by reducing the fuel pressure in the fuel flow path 15 and the fuel chamber 47 with the stop of the engine as the engine is stopped. Then, the clearance 19 is opened.

  That is, the annular body 43 is elastically deformed to the outer peripheral side by increasing the pressure of the fuel chamber 47, so that the combustion gas that blocks the diffusion of the combustion gas to the clearance 19 on the tip side of the Teflon ring 29 (Teflon is a registered trademark). Form a blocking structure.

[Effect of Example 1]
The injector 1 of the first embodiment includes an annular body 43 that is annularly attached to the outer periphery on the tip side of the valve body 20 relative to the Teflon ring 29 (Teflon is a registered trademark). And the clearance 19 is closed, and the clearance 19 is opened when the engine is stopped.
Thereby, since the clearance 19 is formed between the outer periphery of the annular body 43 and the inner wall surface 18 of the mounting hole 3 when the engine is stopped, the possibility that the annular body 43 damages the inner wall surface 18 when the injector 1 is removed is low. In addition, when the injector 1 is mounted, the risk that the annular body 43 damages the inner wall surface 18 is low. For this reason, even if maintenance or the like is repeated, the inner wall surface 18 is less likely to be damaged, so the effect of blocking the combustion gas by the annular body 43 does not decrease.

The annular body 43 is welded to the valve body 20 to form an annular fuel chamber 47 together with the valve body 20, and the fuel chamber 47 communicates with the fuel flow path 15. The annular body 43 elastically deforms to the outer peripheral side by closing the clearance 19 by increasing the fuel pressure in the fuel flow path 15 and the fuel chamber 47 as the engine is started. When the fuel pressure in the fuel chamber 47 is reduced, the clearance 19 is opened by elastic deformation toward the inner peripheral side.
As a result, the fuel pressure in the fuel flow path 15 and the fuel chamber 47 is increased with the start of the fuel supply device and the clearance 19 is closed, so that combustion occurs before the first explosion after the engine is started (hereinafter referred to as the first explosion). A gas blocking structure is formed. For this reason, in the injector 1 in which the combustion gas blocking effect does not decrease even when maintenance or the like is repeated, the combustion gas due to the first explosion can be blocked reliably.

  Further, since the fuel chamber 47 and the fuel flow path 15 are communicated with each other by the throttle 48, the influence of the pressure pulsation in the fuel flow path 15 on the fuel pressure in the fuel chamber 47 is greatly reduced, and the annular body 43 is stable. Therefore, the clearance 19 can be closed to maintain the combustion gas blocking effect.

[Example 2]
According to the injector 1 of the second embodiment, as shown in FIG. 3, the annular body 43 is welded to the valve body 20 so as to partially cover the distal end surface 50 of the valve body 20 where the injection hole 16 opens. . That is, the annular body 43 is provided in a substantially cylindrical shape with a bottom, and is provided so as to have a cylindrical portion 51 that is arranged coaxially with the axial direction and a bottom portion 52 that covers the distal end surface 50. Further, the bottom portion 52 is provided in an annular shape so as to cover a portion on the outer peripheral side with respect to the opening portion of the nozzle hole 16 on the distal end surface 50.

  The annular body 43 is circumferentially welded to the outer peripheral surface of the valve body 20 at the rear end of the cylindrical portion 51 (see the welded portion 46 in the figure), and is circumferentially formed on the distal end surface 50 of the bottom portion 52. It welds (refer the welding site | part 45 in the figure), and the cyclic | annular fuel chamber 47 is formed between the front-end | tip of the cylindrical part 51, and the welding site | part 46. FIG.

  As a result, the annular body 43 shuts off the combustion gas and receives heat directly from the combustion gas on the tip end side of the valve body 20. For this reason, since the amount of heat received from the combustion gas can be reduced at the tip surface 50, the effect of lowering the temperature around the injection hole 16 of the injector 1 can be enhanced.

[Reference example]
According to the injector 1 of the reference example , as shown in FIG. 4, the annular body 43 is provided so as to form an inner and outer double circular section, that is, an outer portion 54 and an inner portion 55, and the outer periphery of the valve body 20. Is held in. Further, the inner portion 55 has a higher expansion rate than the outer portion 54. The annular body 43 is heated by the combustion heat of the fuel and expands to the outer peripheral side to close the clearance 19, and is cooled to contract to the inner peripheral side to open the clearance 19. That is, the annular body 43 is held by the valve body 20 so as to be thermally deformable in the radial direction.

  Thereby, when high temperature combustion gas exists in the combustion chamber 4, the clearance 19 is reliably closed by the thermal expansion of the annular body 43 (see FIG. 4C). For this reason, depending on only the temperature of the combustion chamber 4, a combustion gas blocking structure can be formed without being influenced by other external factors.

  Further, since the outer portion 54 exposed to the combustion gas can be provided by a material different from that of the inner portion 55, the outer portion 54 selects materials with an emphasis on heat resistance, and the inner portion 55 has a coefficient of thermal expansion. Material can be selected with emphasis on. For this reason, the annular body 43 excellent in both heat resistance and a thermal expansion coefficient can be provided.

  Here, the outer portion 54 is provided with, for example, stainless steel as a material with an emphasis on heat resistance. In addition, the inner portion 55 is provided with a metal having a high expansion coefficient such as copper as a material with an emphasis on the thermal expansion coefficient. Further, the inner portion 55 can be formed by enclosing a liquid that exists at room temperature such as water or a gas that exists at room temperature such as an inert gas such as nitrogen gas or helium gas.

[Modification]
The injector 1 of the embodiment has been intended directly injects fuel into the combustion chamber 4 is mounted to the engine head 2 of a gasoline engine, it is attached to the injector 1 into the intake pipe, as in Example 1 to 2 Similar effects can be obtained. That is, when fuel is injected into the intake pipe to form an air-fuel mixture, the tip of the injector 1 may receive heat due to the internal EGR effect in which combustion gas flows back to the intake pipe. The injector 1 due to such an internal EGR effect According to the injector 1 of the embodiment, it is possible to effectively form a combustion gas blocking structure against the heat received at the tip.

  Furthermore, even if the injector 1 is attached to a diesel engine, the same effect as in the embodiment can be obtained.

It is a whole block diagram of an injector (Example 1). (A) is principal part sectional drawing which shows the annular body before a deformation | transformation, (b) is principal part sectional drawing which shows the annular body after a deformation | transformation (Example 1). (A) is principal part sectional drawing which shows the annular body before a deformation | transformation, (b) is principal part sectional drawing which shows the annular body after a deformation | transformation (Example 2). (A) is principal part sectional drawing of an injector, (b) is principal part sectional drawing which shows the annular body before a deformation | transformation, (c) is principal part sectional drawing which shows the annular body after a deformation | transformation ( reference) Example ).

1 Injector 3 Mounting hole 7 Needle valve 15 Fuel flow path 16 Injection hole 18 Inner wall surface (inner wall surface of mounting hole)
19 Clearance 20 Valve body 43 Annular body 47 Fuel chamber 48 Restriction 50 Front end surface

Claims (3)

In an injector that is installed in a predetermined mounting hole and injects fuel to the engine,
A valve body provided in a substantially cylindrical shape, having a fuel injection hole at the tip, and forming a clearance between the inner wall surface of the mounting hole and the outer peripheral surface thereof;
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 annular body that is annularly mounted on the outer periphery of the tip of the valve body, is deformed to the outer peripheral side when the engine is started, closes the clearance, and includes an annular body that opens the clearance when the engine is stopped ,
The annular body is welded to the valve body to form an annular fuel chamber together with the valve body;
The fuel chamber communicates with the fuel flow path by a throttle that penetrates the valve body.
The annular body is
By increasing the fuel pressure in the fuel flow path and the fuel chamber with the start of the engine, it is deformed to the outer peripheral side to close the clearance,
The injector is characterized in that when the engine is stopped, fuel pressure in the fuel flow path and the fuel chamber is reduced, so that the fuel is deformed to an inner peripheral side to open the clearance . The injector according to claim 1, wherein
The injector is characterized in that the annular body is welded to the valve body so as to partially cover a front end surface of the valve body where the nozzle hole is opened . Injector according to claim 1 or claim 2,
The injector is characterized in that the annular body is made of a metal material having higher elasticity than the valve body .

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