JP2008014156A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve suitable for optimizing a spray shape both at low temperatures and at high temperatures. <P>SOLUTION: In the fuel injection valve 1, a nozzle plate 5 having a plurality of fuel injection holes 16 and regulating the fuel spray state is provided on the downstream side of an opening-closing valve 3 comprising a valve seat 6 and a valve element 7 on a fuel passage. The nozzle plate 5 comprises bimetal in which a central part is bent in the fuel blowout direction with respect to a peripheral part in accordance with temperature rise. The fuel spray angle is narrowed at low temperatures, and is expanded at the time of temperature rise. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection valve for an internal combustion engine, and more particularly to a fuel injection valve suitable for fuel injection into an intake port.

  In conventional engines that inject fuel into the intake port, a fuel injection valve that prevents fuel from adhering to the inner wall of the intake port has been proposed to reduce unburned hydrocarbons (HC) contained in the exhaust gas. (See Patent Document 1).

This is composed of a fuel injection valve capable of injecting a main spray having a wide spray angle and a low penetrating force and a lead spray having a narrow spray angle and a high penetrating force.
JP 2003-120476 A

  However, in the above-described conventional example, the injection holes provided in the nozzle plate are formed by the injection holes for main spray having a wide spray angle and low penetrating force and the injection holes for lead spray having a narrow spray angle and high penetrating force. As a result, the spray shape is constant both at low and high temperatures, and part of the main spray always adheres to the inner wall of the intake port. There has been a problem that the spent fuel enters the combustion chamber in a liquid film state without being vaporized in the intake port and is discharged as unburned hydrocarbon (HC).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injection valve suitable for achieving an optimum spray shape at both low and high temperatures.

  The present invention is a fuel injection valve provided with a nozzle plate provided with a plurality of fuel injection holes to regulate the spray state of fuel downstream of an on-off valve comprising a valve seat and a valve body of a fuel passage, Is formed of a bimetal whose central portion is curved in the direction of fuel ejection with respect to the peripheral portion as the temperature rises, and the fuel spray angle is set as a narrow angle when the temperature is low, and the fuel spray angle is increased when the temperature rises.

  Therefore, according to the present invention, the nozzle plate is formed of a bimetal whose central portion is curved in the fuel ejection direction with respect to the peripheral portion as the temperature rises. Because the angle is increased, the nozzle plate shape determined by the engine temperature during cold start and startup forms an optimal spray that forms a narrow angle that does not easily adhere to the wall surface of the intake port. While reducing hydrocarbons, after warming up, it is curved by receiving heat in the engine to widen the spray angle and reduce the spray particle size, improving the charging efficiency by the effect of latent heat of vaporization on the wall surface of the intake port, The output can be improved.

  Hereinafter, the fuel injection valve of this invention is demonstrated based on each embodiment.

(First embodiment)
1 to 9 show a first embodiment of an electromagnetic fuel injection valve to which the present invention is applied, and FIG. 1 is a cross-sectional view of a main part of the electromagnetic fuel injection valve of the first embodiment and a front view of an injection hole. 2 is a cross-sectional view of a nozzle plate used in the fuel injection valve of the first embodiment, FIGS. 3 to 8 show operating states and operating characteristics, respectively, and FIG. 9 is a main portion of the fuel injection valve of the second embodiment. It is sectional drawing of this and the front view of an injection hole.

  In FIG. 1, an electromagnetic fuel injection valve 1 according to the first embodiment is mainly used for a fuel supply type engine that injects fuel into an intake port of an engine, and includes a housing main body 2 and a housing main body 2. The valve device 3 provided in the inside, the solenoid device 4 which drives the valve device 3, and the nozzle plate 5 which is provided downstream of the valve device 3 and sets the spray angle and spray shape of the fuel to be injected. The fuel injection valve 1 is a cylinder head or an intake manifold in a state where a tip portion for injecting fuel is inserted into an injection valve insertion hole A provided in an intake port provided in a cylinder head of an internal combustion engine or an intake manifold connected thereto. Fixed to. Then, high-pressure fuel is supplied to the inside from a fuel supply pipe (not shown).

  The valve device 3 includes a valve seat 6 fixed in a cylindrical inner housing 2A, a valve body 7 seated on the valve seat 6, and a valve for connecting the valve body 7 to an armature 10 of a solenoid device 4 to be described later. And a rod 7A. The valve seat 6 is fixed in the inner housing 2A in a state where the outer peripheral surface is closely fitted to the inner housing 2A. A small-diameter hole portion 6A is connected to the inner peripheral side from the distal end side to the small-diameter hole 6A. And a tapered seat portion 6B on which the valve body 7 is seated with the inner diameter gradually enlarged, and a large-diameter hole portion 6C that is connected to the rear end of the seat portion 6B and holds the valve body 7 from the outer periphery. The rear end of the large-diameter hole 6C is provided with a portion whose diameter is gradually increased. The valve body 7 has a substantially spherical shape, and its outer peripheral portion is guided by the large-diameter hole 6C of the valve seat 6 so as to be movable in the axial direction of the inner housing 2A. It is configured to be seated.

  The solenoid device 4 is connected to the valve body 7 of the valve device 3 via a valve rod 7A, and is fixed in the inner housing 2A and an armature 10 that is slidably inserted in the inner housing 2A. A hollow core 11, a coil 12 fitted to the outer periphery of the inner housing 2 </ b> A, and an outer peripheral housing 2 </ b> B that accommodates the coil 12 and is closely fixed to an outer peripheral region that accommodates the core 11 and the armature 10 of the inner housing 2 </ b> A. With. The outer peripheral housing 2B surrounds the coil 12, and contacts the outer periphery of the armature 10 and the core 11 via the inner housing 2A, thereby forming a magnetic circuit. The outer housing 2B is provided with a flange 2C for positioning the fuel injection valve 1 when inserted into the injection valve insertion hole A of a cylinder head or the like, and an annular provided between the back surface of the flange 2C and the coil housing portion. The seal ring 2D fitted in the groove 2D is brought into contact with the inner periphery of the injection valve insertion hole A and fixed in a sealed state.

  The armature 10 is biased toward the valve device 3 by a built-in spring 13 so that the valve body 7 is seated on the valve seat 6 via a valve rod 7A. Further, when a drive current is supplied to the coil 12, the magnetic circuit is formed, and the armature 10 is driven to the core 11 side against the spring 13 to come into contact with the core 11, whereby the valve device 3 is separated from the valve seat 6 and the valve device 3 is opened.

The nozzle plate 5 is fixed to the end face of the valve seat 6 of the valve device 3 by laser welding B or the like, and as shown in FIG. 2, two metal plates 15A and 15B are bonded and bonded together. A plurality of fuel injection holes 16 are provided in the central region. The metal plate 15A disposed on the valve seat 6 side of the two metal plates 15A and 15B is made of a low expansion metal having a relatively low thermal expansion coefficient, such as an Fe—Ni alloy, for example, on the tip side. The metal plate 15 </ b> B disposed on the metal plate is made of a so-called “bimetal” made of a high expansion metal having a relatively high coefficient of thermal expansion, such as a Ni—Cr—Fe alloy. The nozzle plate 5 made of this “bimetal” has, for example, a curvature coefficient set to 11.5 × 10 ⁻⁶ [/ ° C.]. Further, the thickness of the nozzle plate 5 is, for example, about 0.1 [mm] in a state where the two metal plates 15A and 15B are bonded together, but the valve device 3 is opened by the solenoid device 4. In the case of deformation when a high fuel pressure is applied, it is necessary to consider increasing the plate thickness to the extent that this deformation does not occur.

  Accordingly, the nozzle plate 5 has a planar shape shown in FIG. 2 at the time of cold start or start at which the tip of the fuel injection valve 1 is relatively low temperature, but at the stage when the engine is warmed up, the center is It is thermally deformed so as to expand and protrude toward the tip side.

  The operation of the electromagnetic fuel injection valve having the above configuration will be described below.

  In the state where the coil 12 of the solenoid device 4 is not energized, the electromagnetic fuel injection valve 1 is pressed against the valve device 3 side by the urging force of the spring 13 as shown in FIG. The valve body 7 is seated on the valve seat 6, and the fuel introduced to the back surface of the valve body 7 is in a state of being blocked from being ejected by the valve device 3 in the valve closing state. No fuel is supplied to the plate 5.

  When the coil 12 of the solenoid device 4 is energized from the outside, a magnetic flux is generated in a magnetic path constituted by the armature 10, the core 11, and the outer housing 2B. Is done. Then, the valve body 7 integrated with the armature 10 is separated from the seat portion 6B of the valve seat 6 and raised to a position where the end face of the armature 10 abuts against the core 11.

  As the valve body 7 moves up, the fuel introduced into the back surface thereof is supplied to the small diameter hole 6A side of the valve seat 6 via the gap between the seat portion 6B of the valve seat 6 and the valve body 7, and the nozzle plate 5 reaches the back surface and is sprayed through the fuel injection holes 16 of the nozzle plate 5 in a sprayed state.

  The spray direction of the fuel ejected from the fuel injection holes 16 of the nozzle plate 5 is flat when the engine is cold and started, as shown in FIG. The fuel is sprayed by (which is also the spray angle at the time of assembly). A region indicated by a broken line in FIG. 4 indicates a spread state of the fuel spray injected by the fuel injection valve 1, and the nozzle plate 5 is configured such that all of the sprayed fuel fine particles proceed toward the valve body of the intake valve IV. The injection angle of the fuel injection hole 16 is set.

  In other words, as is generally set in the past, this implementation is performed for the fuel adhesion rate to the intake port when the fuel spray angle is set to a desirable setting angle (wide angle setting) in the entire operation range from the low temperature to the high temperature. It is possible to reduce the fuel adhesion rate to the intake port portion P when the angle is set by the fuel injection valve 1 in the embodiment (setting the included angle). As a result, the amount of unburned hydrocarbons contained in the exhaust gas can also be reduced. The fuel adhesion rate in this case is the ratio of the amount of fuel adhering to the intake port wall surface to the amount of fuel injected from the electromagnetic fuel injection valve 1.

  FIG. 5 is a characteristic diagram showing the results of measuring the relationship between the spray angle at the time of starting at a low temperature and the amount of unburned hydrocarbon (HC) contained in the exhaust gas by an experiment by the present inventor. According to the inventor's experiment, by changing the fuel injection angle from the wide angle setting to the narrow angle setting, the fuel adhesion rate to the port wall surface is reduced by 6 [%], so that the unburned carbonization contained in the exhaust gas. The amount of hydrogen (HC) could be reduced by about 10 [%].

  When the engine is warmed up due to the warm-up operation or the continuation of the operation state, the temperature of the cylinder head is also raised, and the temperature of the fuel injection valve 1 is also raised by receiving the heat. The nozzle plate 5 is formed of “bimetal” in which metal sheets 15A and 15B having different thermal expansions are bonded together, so that the nozzle plate 5 is curved toward the side where the metal plate 15B having a higher thermal expansion coefficient exists. That is, as shown in FIG. 6, in the nozzle plate 5, as a result of the temperature rise, the nozzle plate 5 is curved to the front side where the intake port exists, and as a result, the angle between the fuel injection holes 16 provided in the nozzle plate 5 The (fuel injection angle) is increased and the angle is increased. The spray angle of the fuel injected from the fuel injection holes 16 of the nozzle plate 5 is widened by widening the angle between the fuel injection holes 16. A part of the sprayed fuel comes into contact with the wall surface of the intake port P as shown by the solid line in FIG. 4 and is vaporized by the latent heat effect of vaporization by the wall surface whose temperature has risen, and enters the combustion chamber via the intake valve IV. As a result, the charging efficiency is improved and the output torque is also improved.

  FIG. 7 is a characteristic diagram showing the relationship between the spray angle of the fuel sprayed by the fuel injection valve 1 and the spray particle size, and FIG. 8 is a characteristic diagram showing the relationship between the sprayed fuel particle size and the output torque. is there. According to FIG. 7, the particle size of the sprayed fuel can be reduced by increasing the spray angle as in this embodiment. According to the applicant's test, when the spray angle is increased by 10 [deg], the spray particle size is reduced by 20 [μm].

  Further, as shown in FIG. 8, by reducing the spray particle size, that is, by widening the spray angle, the charging efficiency is improved by the effect of latent heat of vaporization by the port wall surface of the intake port, and the output of the engine is improved. Can do. According to the applicant's test, when the spray angle is increased by 10 [deg] and the spray particle size is decreased by 20 [μm], the engine output is improved by 4 [%].

  In the electromagnetic fuel injection valve 1A of the second embodiment shown in FIG. 9, the nozzle plate 5 is fixed to the tip side plane of the valve seat 6 by laser welding B in the fuel injection valve 1 of the first embodiment shown in FIG. Instead, the outer periphery of the nozzle plate 5 is fixed to the inner periphery of the inner housing 2A by brazing C. In this fixing method, the outer peripheral edge of the nozzle plate 5 is fixed, the deformation region with respect to the temperature of the nozzle plate 5 is expanded, and the fuel injection angle formed between the fuel injection holes 16 at a high temperature is further increased. Wide angle can be achieved.

  As described above, in the fuel injection valve 1 of the present embodiment, the thermal expansion coefficients of the constituent materials 15A and 15B of the nozzle plate 5 including the fuel injection holes 16 are made different between the front side material 15B and the back side material 15A. The unburned hydrocarbons (HC) contained in the exhaust gas are formed by fuel injection through the fuel injection holes 16 having a narrow fuel spray angle at a low temperature. On the other hand, in the high temperature state after warming up, the spray angle is widened and sprayed by fuel injection through the fuel injection holes 16 whose fuel spray angle is widened by utilizing the thermal deformation of the nozzle plate 5. By reducing the particle size, the charging efficiency can be improved and the engine output can be improved by the latent heat of vaporization of the intake port wall P. That is, it is possible to provide an optimal spray shape that achieves both reduction of unburned gas contained in the exhaust gas and improvement of output according to the temperature condition.

  In the present embodiment, the following effects can be achieved.

  (A) A fuel injection valve 1 provided with a nozzle plate 5 provided with a plurality of fuel injection holes 16 to regulate the fuel spray state downstream of the on-off valve 3 comprising a valve seat 6 and a valve element 7 in the fuel passage. The nozzle plate 5 is formed of a bimetal whose central portion is curved in the fuel ejection direction with respect to the peripheral portion as the temperature rises. The fuel spray angle is defined as a narrow angle when the temperature is low, and the fuel spray angle when the temperature is increased. I tried to enlarge it. Therefore, when the engine is cold and started, the nozzle plate 5 shape determined by the engine temperature forms an optimal spray that forms a narrow angle that is difficult to adhere to the wall surface of the intake port, thereby reducing unburned hydrocarbons contained in the exhaust gas. On the other hand, after warming up, it is curved by receiving heat in the engine to widen the spray angle and reduce the spray particle size, improve the charging efficiency by the vaporization latent heat effect on the intake port wall surface, and improve the output Can do.

  (A) The fuel injection valve 1 is applied to an in-intake-port injection engine that injects fuel into the intake port, and thus the effect (a) can be exhibited.

(Second Embodiment)
10 to 15 show a second embodiment of an electromagnetic fuel injection valve to which the present invention is applied, FIG. 10 is a cross-sectional view of the main part of the electromagnetic fuel injection valve and a front view of an injection hole, and FIG. FIG. 12 is a temperature-displacement characteristic diagram of the nozzle plate, FIG. 13 is an explanatory diagram of a fuel injection state at a low temperature, and FIG. 14 is a fuel at a high temperature. Explanatory drawing of an injection state, FIG. 15 is sectional drawing of the principal part of the electromagnetic fuel injection valve of 2nd Example, and the front view of an injection hole. In this embodiment, the structure which comprised the nozzle plate by the disc spring-like bimetal is added to 1st Embodiment. In addition, the same code | symbol is attached | subjected to the same apparatus and member as 1st Embodiment, and the description is abbreviate | omitted or simplified.

  In FIG. 10, the fuel injection valve 1 </ b> B according to the second embodiment has a disc plate shape in which the nozzle plate 5 </ b> A that is fixed to the end surface on the front end side of the valve seat 6 is curved with a central region protruding toward the valve seat 6 at a low temperature, The configuration using the disc spring-like bimetal that is curved so that the central region is separated from the valve seat 6 side at a high temperature is different from the first embodiment, and the other configurations are the same as the first embodiment.

  In the electromagnetic fuel injection valve 1B of the first embodiment shown in FIG. 10, the vicinity of the periphery of the nozzle plate 5A is circumferentially fixed to the end face of the valve seat 6 by laser welding B. The second embodiment shown in FIG. In the electromagnetic fuel injection valve 1C of the embodiment, the peripheral edge of the nozzle plate 5A is fixed to the inner peripheral surface of the inner housing 2A by brazing C. Note that the end surface of the valve seat 5A is formed with the central portion of the end surface recessed to allow a disc spring-like shape at low temperatures.

  The nozzle plate 5A is a bimetal formed by joining two metal plates 17A and 17B having different coefficients of thermal expansion and is formed into a disc spring shape. As shown in FIG. As shown in FIG. 12, when the increase in the ambient temperature exceeds the reversal temperature, the shape indicated by the chain line in FIG. 11, that is, the center portion is convex downward as shown in FIG. Inverted to a curved state, and the inverted state is maintained even when the temperature rises further. Even when the ambient temperature decreases, the inversion state is maintained until the return temperature is reached, and when the ambient temperature decreases beyond the return temperature, the inversion state indicated by the broken line is reversed to the low temperature shape indicated by the solid line. The shape is changed.

  As described above, the shape at the low temperature and the shape at the high temperature of the nozzle plate 5 </ b> A are largely reversed so as to change, and at low temperatures, the nozzle plate 5 </ b> A is injected from the fuel injection holes 16 as shown in FIG. 13. While the fuel spray angle can be further reduced, the spray angle injected from the fuel injection holes 16 can be further widened at high temperatures, as shown in FIG.

  Therefore, at the time of cooling and starting, fuel spray can be injected from the fuel injection hole 16 of the nozzle plate 5A in a narrow angle state, and the spray can be reduced from adhering to the wall surface of the intake port, and unburned hydrocarbons contained in the exhaust gas The amount of (HC) discharged can be further reduced.

  Further, at a high temperature such as after warm-up, fuel spray atomized in a wider angle state is injected from the fuel injection hole 16 of the nozzle plate 5A, and a part of the atomized fuel sprayed is in the intake port. The fuel is vaporized by the latent heat of vaporization effected by the wall surface that has been heated, and is sucked into the combustion chamber via the intake valve. As a result, the charging efficiency is improved and the output torque is also improved.

  In the present embodiment, in addition to the effects (a) to (b) in the first embodiment, the following effects can be achieved.

  (C) The nozzle plate 5A is shaped like a disc spring with a central portion recessed toward the upstream side where the on-off valve 3 is located with respect to the peripheral portion at low temperatures, thereby further narrowing the fuel spray angle at low temperatures. The sprayed fuel can be set at a narrow angle so that the sprayed fuel does not adhere to the wall surface of the intake port P, and the amount of unburned hydrocarbons (HC) contained in the exhaust gas at the time of starting and cooling is reduced. Can do.

  (D) In addition, the nozzle plate 5A has a central portion that protrudes in the direction of fuel injection from the periphery when the temperature rises after warming up, thereby increasing the fuel spray angle at high temperatures, unlike at low temperatures ( (= Wide angle setting) and the particle size can be reduced, so that a part of the atomized fuel that is sprayed contacts the wall surface of the intake port P and is vaporized due to the latent heat of vaporization effected by the temperature-increased wall surface. As a result, it is sucked into the combustion chamber via the intake valve. As a result, the charging efficiency is improved, the output torque can be improved, and both the exhaust gas characteristics at the low temperature and the output characteristics at the high temperature can be achieved.

Sectional drawing (A) of the principal part of the electromagnetic fuel injection valve which shows the 1st Example of one Embodiment of this invention, and the front view (B) of an injection hole. Similarly sectional drawing of a nozzle plate. Explanatory drawing which shows the nozzle plate shape and fuel spray state in a low-temperature state. The schematic diagram explaining the fuel-injection area | region at the time of low temperature and high temperature. The characteristic view which shows the change of the unburned hydrocarbon discharge | emission amount in exhaust gas with respect to the change of the fuel adhesion rate to the port wall surface at the time of low temperature. Explanatory drawing which shows the nozzle plate shape and fuel spray state in a high temperature state. The characteristic view which shows the relationship between the spray angle of the fuel sprayed with a fuel injection valve, and the spray particle size. The characteristic view which shows the relationship between the particle size of the sprayed fuel, and output torque. Sectional drawing (A) of the principal part of the electromagnetic fuel injection valve which shows 2nd Example of one Embodiment, and the front view (B) of an injection hole. Sectional drawing (A) of the principal part of the electromagnetic fuel injection valve which shows 1st Example of 2nd Embodiment of this invention, and front view (B) of an injection hole. Sectional drawing of the nozzle plate used for the fuel injection valve of 2nd Embodiment. The characteristic figure of the temperature-displacement amount of a nozzle plate. Explanatory drawing of the fuel-injection state at the time of low temperature. Explanatory drawing of the fuel-injection state at the time of high temperature. Sectional drawing (A) of the principal part of the electromagnetic fuel injection valve which shows 2nd Example of 2nd Embodiment, and the front view (B) of an injection hole.

Explanation of symbols

1, 1A, 1B, 1C Fuel injection valve 2 Housing body 3 Valve device 4 Solenoid device 5, 5A Nozzle plate 6 Valve seat 7 Valve body 15A, 15B, 17A, 17B Metal plate 16 Fuel injection hole

Claims (5)

A fuel injection valve provided with a nozzle plate provided with a plurality of fuel injection holes to regulate the spray state of fuel downstream of an on-off valve comprising a valve seat and a valve body of a fuel passage,
The nozzle plate is made of a bimetal whose central portion is curved in the fuel ejection direction with respect to the peripheral portion as the temperature rises, and the fuel spray angle is a narrow angle when the temperature is low, and the fuel spray angle is enlarged when the temperature rises A fuel injection valve characterized by.   2. The fuel injection valve according to claim 1, wherein the nozzle plate is formed in a disc spring shape in which a central portion is recessed toward an upstream side having an on-off valve with respect to a peripheral portion at a low temperature.   The fuel injection valve according to claim 2, wherein the nozzle plate has a central portion that protrudes in the fuel injection direction from the peripheral portion when the temperature rises.   The fuel injection valve according to any one of claims 1 to 3, wherein the fuel injection valve is applied to an in-intake-port injection engine that injects fuel into an intake port. .   The fuel injection valve according to any one of claims 1 to 4, wherein an outer peripheral portion of the nozzle plate is fixed to a housing of the fuel injection valve by brazing.