JP2753312B2 - Fuel injection valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve used in an internal combustion engine, and more particularly, to a fuel passage for swirling fuel with an element provided upstream of a valve seat. Fuel injection valve.

[Conventional technology]

JP-A-55-104564 and JP-A-56-75955 are examples of electromagnetic fuel injection valves of a type in which fuel is swirled upstream of a valve seat. The former has a plurality of inlet orifices and an outlet orifice, the inlet orifices being spaced at a maximum diameter relative to the swirl chamber. The latter includes a fuel swirling element having a guide hole for guiding the valve element, and a plurality of swirl passages for introducing fuel into the guide hole from a tangential direction.

[Problems to be solved by the invention]

In the fuel injection valve of the related art, workability for forming a fuel passage (swirl passage) for giving a swirling force to the fuel and sufficient adjustment of the fuel injection angle to an operation characteristic of the engine are sufficient. No consideration was given. In particular, in a fuel injection valve having a fuel passage that gives a swirling force to the fuel, pressure loss in the fuel passage may have a great effect on the fuel injection amount as well as the swirl force applied to the fuel. For this reason, in order to set the fuel injection angle of the fuel injection valve to an appropriate angle, it is desirable to reduce the effect of pressure loss in the fuel passage that gives a slewing force to the fuel and change the slewing force applied to the fuel. .

Therefore, an object of the present invention is to provide a fuel injection valve having improved workability for forming a fuel passage for giving a turning force to fuel and having an appropriate fuel injection angle.

[Means for solving the problem]

In order to achieve the above object, the fuel injection valve of the present invention
A nozzle body having an injection hole and a valve seat on the upstream side of the injection hole, a valve body for opening and closing the fuel passage between the valve seat, and a valve body disposed upstream of the valve seat and supplied. In a fuel injection valve having an element for forming a fuel passage for giving a swirling force to fuel, an outer diameter of the element as viewed from the valve axis direction is formed in a polygonal shape, and a plane portion of an outer periphery of the polygonal shape is formed. An axial fuel passage is formed with the inner wall surface of the nozzle body, and a radial fuel passage connected to the axial fuel passage and eccentric with respect to the valve axis at the valve seat side surface of the element. The radial fuel passage is formed such that an inlet of the radial fuel passage is shifted to an end side from a circumferential center of the flat portion, and a sectional area of the radial fuel passage is larger than a sectional area of the injection hole. .

Further, the fuel injection valve of the present invention is a nozzle body having an injection hole and a valve seat upstream of the injection hole, a valve body for opening and closing a fuel passage between the valve seat, An element disposed on the upstream side and forming a swirl passage for applying a swirling force to the supplied fuel, wherein the element extends in a direction along the axis from the upper end to the lower end of the outer peripheral surface thereof. And a plurality of axial fuel passage surfaces formed at intervals in the circumferential direction of the outer peripheral surface, and along the axial center using the axial fuel passage surface and the inner wall surface of the nozzle body. Directional fuel passage, and a lower end of the fuel passage is connected to a radial fuel passage that applies a turning force to the fuel, and the inlet of the radial fuel passage is located at a position closer to the center of the fuel passage surface in the axial direction in the circumferential direction. Also shifted to the end side, the cross-sectional area of the radial fuel passage is larger than the cross-sectional area of the injection hole. One in which the.

Further, in the fuel injection valve of the present invention, the radial fuel passage may be formed by a groove formed on a surface of the element for forming the swirl passage on the valve seat side.

Further, in the fuel injection valve of the present invention, the radial fuel passage may be constituted by a plurality of fuel passages, and the total sectional area of these fuel passages may be larger than the sectional area of the injection hole.

[Action]

According to the above means, the axial fuel passage can be formed by the easy processing using the outer peripheral surface of the element, and the entrance of the radial fuel passage is shifted in the circumferential direction of the axial fuel passage surface. Thereby, the turning force of the fuel can be changed. At this time, the cross-sectional area of the fuel passage in the radial direction is made larger than the cross-sectional area of the injection hole to reduce the effect of pressure loss in the fuel passage in the radial direction on the fuel injection characteristics. Can be changed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. The structure and operation of the electromagnetic fuel injection valve (hereinafter, referred to as “injection valve”) 1 according to the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 2 denotes a substantially cylindrical housing for accommodating main working parts of the injection valve 1, and a nozzle device 3 described below is mechanically fixed and held below the housing 2.

A valve seat 4 is formed in a lower inner surface of the nozzle device 3, and a fuel injection hole 5 is formed in a lower axis thereof. Further, a cylindrical fuel swirling element 7 is mechanically fixed in a rapidly expanding hole 6 provided in the vicinity of the valve seat 4. 9 is a valve device 3
A ball 10 is fixed to the lower end of the rod 9 and a cup-shaped plunger 11 made of a magnetic material is fixed to the other end of the rod.
The ball 10 slides inside the inner wall surface 7a of the fuel swirling element 7 in the axial direction. When the ball 10 is seated on the valve seat 4, the fuel injection hole 5 is closed, but when the ball 10 is separated from the valve seat 4, the fuel injection hole 5 is opened. The fuel that reaches the fuel injection holes 5 is
The fuel flows from the grooves 12 and 13 provided in the fuel swirling element 7, and these grooves are constituted by an axial groove 12 having a sufficient space to allow the passage of fuel and a radial groove 13 having a small fuel flow loss. The first fuel swirl chamber 14 at the outlet of the radial groove 13
Flows into Reference numeral 15 denotes a second fuel swirl chamber formed between the lower portion of the ball 10 and the conical valve seat 4, which promotes a swirl flow of the fuel flowing from the first fuel swirl chamber 14. Reference numeral 16 denotes a horse-shaped spacer member inserted between the bearing surface 2a of the housing 2 and the bearing surface 3a of the nozzle device 3.
16 regulates a gap between the valve device 8 and the protruding surface 8a to secure upward movement of the valve device 8, that is, a lift amount.

A tubular iron core 17 is provided in the center of the housing 2, and the iron core 17 is mechanically connected to an upper portion of the housing 2. An iron pipe 17 is provided in the iron core 17.
A spring 19 is in contact with the lower end of 18. The other lower end surface of the spring 19 is in contact with the inner surface of the recess of the plunger 11 of the valve device 8. That is, the urging force of the spring 19 is
The ball 10 acts in the direction of seating on the valve seat 4.

An electromagnetic coil 21 wound around a bobbin 20 is housed in an annular space formed between the inner periphery of the housing 2 and the outer periphery of the iron core 17. The electromagnetic coil 21 is connected to a terminal 23 mounted in a synthetic resin connector 22 formed integrally with the housing 2. The terminal 23 is connected to an electronic control device (not shown) such as a computer, and receives a pulse signal from the electronic control device.

The operation of the injection valve 1 having such a configuration will be described below. The fuel pressurized to the predetermined pressure reaches the fuel swirling element 7 through the vicinity of the electromagnetic coil 21 and the valve device 8. Thereafter, the fuel swirl element 7 reaches the valve seat 4 from the axial groove 12 and the radial groove 13 through the first fuel swirl chamber 14.

When a pulse signal is not supplied to the electromagnetic coil 21 from an electronic control unit (not shown), the iron core 17 is not magnetized, and the valve device 8 is pressed against the valve seat 4 by the urging force of the spring 19, and 5 is closed.

When a pulse signal is applied to the electromagnetic coil 21 from the electronic control unit, the iron core 17 is magnetized, whereby the plunger 11 is magnetized.
Is attracted to the iron core 17 against the urging force of the spring 19. Therefore, the valve device 8 is lifted upward and separated from the valve seat 5, so that the fuel injection hole 5 is opened and the stopped fuel is injected.

Here, the fuel atomization of the injection valve 1 will be briefly described. Since the loss of the pressurized fuel passing through the axial groove 12 and the radial groove 13 of the fuel swirling element 7 provided in the rapidly expanding hole 6 of the nozzle device 3 is very small, The first fuel swirl chamber 14 is reached. Here, the fuel whose injection pressure is maintained is efficiently replaced with swirling fuel, and reaches the second fuel swirling chamber 15. In the second fuel swirl chamber 15, swirling is further promoted. Here, in the fuel flow in the first fuel swirl chamber 14 and the second fuel swirl chamber 15, an unstable flow such as sliding cannot occur, and the swirl flow efficiently occurs. Therefore, since the fuel is injected with sufficient injection pressure and swirling force, excellent atomized fuel can be obtained.

Next, the configuration of the radial groove 13 of the fuel swirl element 7, which is the main object of the present invention, will be described with reference to FIGS.

FIG. 2 is an enlarged sectional view of a main part of the nozzle device 3 and the valve device 8. The fuel flows in the direction of the arrow in the figure, and from the axial groove 12 of the fuel swirl element 7 faces the first fuel swirl chamber 14 via the radial groove 13 according to the present invention, and the second fuel swirl chamber downstream. 15, and then flows to the fuel injection hole 5. In the figure, d represents the diameter of the inner wall surface 7a of the fuel swirling element 7.

FIG. 3 is a sectional view taken along the line AA of FIG. The end face 13a ( ₁₁ portion) of the radial groove 13 on the valve shaft center side of the present invention, the other end face 1 of the groove
3b (l ₂ parts), and the center position is indicated. The center position is the so-called center between the valve shaft center and the inner wall surface 7a of the fuel swirling element 7, and is 1/2 of the equivalent diameter d of the inner wall surface 7a. The width w of the groove is represented by l ₂ −l ₁ . The fuel having passed through the radial groove 13 is guided to the first fuel swirl chamber 14 facing the fuel tank, and is injected from the fuel injection hole 5 through the second fuel swirl chamber 15 shown in FIG.

Note that the cross-sectional area Am of the radial groove 13, the ratio A _m / A.theta. The cross-sectional area A.theta. Of fuel injection holes 5 are designed to be 4 or more, in flow losses the groove 13 negligible It is. Less than,
In the description of FIGS. 4 to 7, the cross section of the groove is based on the above.

Figure 4 is a valve between the axis-side end face 13a and the valve axis distance l ₁ of the radial grooves 13, and shows the relationship between injection angle. When the end face 13a is closer to the axis than the center position according to the present invention,
The injection angle is shown to satisfy the allowable angle of the MPI system. Further, in the figure, as the end face 13a approaches the axis side, the swirling force of the fuel flowing to the first fuel swirl chamber 14 is weakened, and the injection angle is reduced. Therefore, it is possible to respond according to the branch pipe shape (space space) of the intake manifold depending on the system.

FIG. 5 shows the relationship between the distance between the valve shaft center and the groove end face and the variation in the injection amount. In the figure, 13c indicates the end face on the valve shaft center side, and 13d indicates the other end face, both of which are distinguished from FIG. As is evident in FIG. 4, the time variation of the injection amount becomes smaller by gradually moving the groove end face away from the valve axis. That is, a stable flow is created. The arrangement of the groove end faces 13c and 13d in the figure is equivalent to that according to the present invention, and sufficiently satisfies the allowable value of the injection amount variation.

FIG. 6 shows the first fuel swirl chamber 14 when the other end surface 13f of the groove is arranged at a position in contact with the inner wall surface 7a of the fuel swirl element 7.
It shows the flow pattern inside. There is no unstable flow such as sliding, and a clean and stable flow is formed. The time variation of the static flow rate is shown in the figure, and the variation width is 1% or less. FIG. 6 may be considered equivalent to the case where the other end surface 13d of the groove shown in FIG. 5 is moved to a position in contact with the inner wall surface 7a, and the other end surface 13d and the inner wall surface 7a of the groove in the state shown in FIG. In the meantime, the arrangement of the other end face 13d can obtain a stable flow with a small variation in the injection amount even at a desired position. From the above, items 3 and 4 according to the present invention will be clarified.

The variation in the flow rate is calculated by using the variation width ΔQ and the average flow rate shown in the time change curve of the flow rate shown in FIG. Indicated by

FIG. 7 shows the relationship between the cross-sectional shape of the radial groove 13 and the flow characteristics. The flow in the groove 13 having a cross-sectional shape indicated by a solid line can take a more stable flow. . That is, the unstable flow in the groove 13 can be removed, and the passage loss of the fuel can be reduced.

Next, adjustment of the stroke of the ball valve will be described. The stroke is determined by the size of the gap between the receiving surface of the neck of the rod 9 and the stopper.

FIG. 8 shows the experimental results of the effect of this stroke 1 on the static flow rate. As can be seen, accompanied connexion flow rate increase in the stroke l gradually slope began rapidly increases substantially constant flow rate Q ₀ becomes gradual. Yotsute this stroke, the area A ₂ of the annular gap formed between the ball 10 and the valve seat 9, reference is made to the Figure 9, is given by the formula.

Here, D _1: drawing trapezoidal lower side D _2: figure trapezoidal upper side, i.e. the seat diameter h: the height of the trapezoid in Fig.

Area A ₂ for a constant flow rate Q ₀ is 1 <[delta] When expressed as the ratio [delta] = A ₂ / A ₃ of the area A ₃ of the fuel injection hole 5. In this example, as shown in FIG. 8, the tolerance ± a the reference stroke l _0, it can be seen that is set to a dimension with a sufficient margin. The ratio δ at the tolerance −a of the stroke l ₀
Is 2 or more. The dimension a is about 20 μm as described above.
It is about.

As described above, the stroke amount of the ball valve is an absolute amount that does not affect the static flow rate, and is determined with a sufficiently large dimensional tolerance. Therefore, as in the prior art, once the lift amount is measured in a state where the ball valve and the valve guide are combined, the end face of the valve guide or
There is no need to polish the receiving surface of the neck of the rod 9 to adjust the stroke to the target range, and it is only necessary to manage the component dimensions.
Accordingly, the assembly operation is easy and simplified.

Next, the influence on the static flow rate of the fuel injection hole 5 which is a fuel outlet provided in the valve guide will be described. As for the static flow rate of the fuel passing through the single fuel injection hole 5, the variation rate of the static flow rate at the tolerance ± b with respect to the reference orifice is less than ± 1.5%. Here, the dimension b is about 5 μm.

As described above, the cross-sectional area A ₃ of the fuel injection hole 5 can be expressed as A ₁ > A by expressing the relationship using the annular gap area A ₂ and the groove area A ₁ of the fuel swirling element 7 during the stroke of the ball valve. _2> A ₃ ... made (6). In the so-called injection valve 1 of this embodiment, fuel is measured by the fuel injection hole 5 of the orifice.

As described above, the ratio δ of A ₂ / A ₃ takes a value of 2 or more. At this time, the fluid loss of the fuel injection hole 5 is 95% of the total loss.
As described above, it is supported that the above-described measurement is performed by the fuel injection holes 5.

Here, FIG. 10 shows the relationship between the fuel flow path and the flow velocity when the injection valve of the present invention is used. As is clear from FIG. 10, the flow rate of the fuel injection hole from the fuel introduction portion to the outlet is the highest. Therefore, the flow rate can be measured only at the fuel injection hole, that is, at the outlet orifice. The design means that the flow rate can be measured accurately if the outlet orifice is made accurately.

In this manner, the spray angle is formed in the radial groove of the fuel swirl element without pressure loss, and the flow velocity at the fuel injection hole is maximized, so that the pressure loss can be further reduced.

FIG. 15 is a configuration diagram of an engine control system equipped with the fuel injection valve according to the present invention.

In FIG. 15, an engine 100 is a well-known fire ignition type engine using gasoline as fuel, and its intake system includes an air cleaner 110, a throttle body 120, and an intake manifold 13.
0, the fuel injection valve 140 of the present invention. On the other hand, the exhaust system includes an exhaust manifold 150, an oxygen sensor 160 for measuring the oxygen concentration in the exhaust gas, a three-way catalytic converter 170 for purifying the exhaust gas, and a muffler (not shown).

Here, the throttle body 120 is composed of an air flow sensor 180, a throttle valve 190, and a throttle sensor 200, and accurately measures the flow rate of air supplied to the engine 100. Also, the three-way catalytic converter 170
It purifies NOx, CO, and HC in exhaust gas from the engine 100 operated near the stoichiometric air-fuel ratio at a high purification rate at the same time.

The engine 100 is equipped with a combustion chamber 220 disposed facing the ignition plug 210, an intake hole 230 and an intake valve 240 for opening and closing the intake hole 230, and a water temperature sensor is provided on a side of the combustion chamber 220. A rotation sensor 260 is disposed at the lower part 250 to detect the operation state. 270 is an igniter, 280
Is a distributor, 290 is an exhaust gas temperature sensor, 300 is an electronic control unit for controlling the operation of the component devices, and arrows in the figure indicate the respective input / output systems.

Further, the fuel injection valve 140 is attached to the wall of the intake manifold 130 upstream of the intake valve 240, and can be injected in the direction of the valve seat 240a of the intake valve 240.

In such a gasoline engine, the combustion chamber
A predetermined amount of intake air is drawn into 220 from the intake system.

Fuel corresponding to the amount of intake air is injected and supplied from the fuel injection valve 140 in the direction of the valve seat 240a with good atomization performance and responsiveness to injection pressure. The injected fuel is efficiently and uniformly mixed with the intake air. In the combustion chamber 220, the air-fuel mixture is sucked and compressed in a compression step, and then the ignition plug 210
To ignite and burn, and to perform combustion accurately.

The combustion gas discharged from the engine 100 is released from the exhaust system into the atmosphere.

Now, when the operation state of the engine 100 is detected by the water temperature sensor 250, the rotation sensor 260, and the like, an air amount corresponding to the operation state is required.This air amount is determined by the opening of the throttle valve 190, The amount of air is accurately measured by the air flow sensor 180. in this case,
The electronic control unit 310 generates a signal for driving the fuel injection valve 140 according to a signal from the air flow sensor 180 or the throttle sensor 200, and the injection amount is determined according to the signal.

A mixture of fuel and air is guided from an intake hole 230 of the engine 100 to a combustion chamber 220, compressed in a compression step, and ignited and burned by a spark plug 210. The combustion state is monitored by an oxygen sensor 160 provided in a collection part of the exhaust manifold 150, and the electronic control unit 300 responds to an output signal of the oxygen sensor 160 so that a predetermined mixture ratio (air-fuel ratio) is always obtained. The injection amount of the fuel injection valve 140 is corrected. As a result, the purification rate of the three-way catalytic converter 170 that simultaneously processes the three components of NOx, CO, and HC in the exhaust gas is kept at the highest.

FIG. 12 is an enlarged view of a fuel injection part in the multipoint injector system shown in FIG. Twelfth
In the figure, the fuel is injected from an electromagnetic fuel injection valve 140. The fuel is sprayed toward the intake valve plate 241 of the intake valve 240. The injection angle is determined so as to be within a range connecting the end of the cylinder head 310 connected to the intake pipe on the combustion chamber side and the fuel injection hole of the electromagnetic fuel injection valve 140. As described above, if the fuel injected into the plate portion of the intake valve can be filled, the sufficiently vaporized mixed gas is sent to the combustion chamber, so that the combustion efficiency can be improved. As a result, there is also an effect as an internal combustion engine that the concentration of CO in the exhaust gas decreases. In the present invention, the spray angle is adjusted by arranging the radial groove of the fuel swirling element on the valve shaft center side.

On the other hand, if the injection angle is large, when the fuel is injected to the inner wall of the cylinder head 241, the fuel remains on the inner wall surface, resulting in a mixture having a different mixing ratio, that is, an uneven mixture, resulting in poor combustion efficiency.

In the internal combustion engine of the multipoint injector system, it is necessary that the fuel injected into the intake valve plate portion 241 of the intake valve 240 be filled.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, since the fuel path which gives a turning force to fuel can be comprised by easy processing, workability | operativity is improved and the influence of the pressure loss in this fuel path is reduced, and the turning force of a fuel is easily changed. Therefore, a fuel injection valve having an appropriate fuel injection angle can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve according to the present invention,
FIG. 2 is an enlarged sectional view of a main part of the nozzle device and the valve device. FIG. 3 is a sectional view taken along the line AA of FIG. 2 for explaining the position of the groove end face of the present invention. 6 is a diagram showing the relationship between the end face position of the groove and the performance according to the present invention, FIG. 7 is a diagram showing the relationship between the cross-sectional shape of the groove and the performance, and FIG. 8 is a diagram showing the relationship between the ball valve stroke and the flow rate. FIG. 9, FIG. 9 is a view for explaining an annular gap generated between a ball valve and a valve seat, FIG. 10 is a view showing a relationship between a fuel flow path and a flow velocity, and FIG. 11 is an engine to which an injection valve according to the present invention is applied. FIG. 12 shows a control system, and FIG. 12 is a partially enlarged view of FIG. DESCRIPTION OF SYMBOLS 1 ... Electromagnetic fuel injection valve, 4 ... Valve seat, 5 ... Fuel injection hole, 7 ... Fuel swirl element, 7a ... Inner wall surface, 12 ... Axial groove, 13 ... Radial groove, 13a , 13c, 13e... Axial end face of the groove, 13b, 13d, 13f.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Ishikawa 2520 Takada, Kata-shi, Ibaraki Inside Sawa Plant, Hitachi, Ltd. (72) Inventor Tokuo Kosuge 2520 Takata, Kata-shi, Ibaraki Co., Ltd. Hitachi, Ltd. Sawa Plant (72) Inventor Hirohisa Mizuno 2520, Kojita, Katsuta-shi, Ibaraki Prefecture Hitachi, Ltd. Sawa Plant (72) Inventor Shiya Sakai 4-6-6-1 Kanda Surugadai, Chiyoda-ku, Tokyo Inside the factory (72) Inventor Eiji Hamajima 2477 Kashima Yatsu, Kata-shi, Ibaraki Pref. Hitachi Motor Engineering Co., Ltd. (56) References JP-A-2-207171 (JP, A) Japanese Unexamined Patent Publication (Kokai) No. 2-115963 (JP, A) JP-A-63-105228 (JP, A) JP-A-61-226559 (JP, A) JP-A-56-75955 (JP, A) JP-A-55-104564 (JP, A) JP-A-1-130067 (JP, U) JP-A 60-97373 (JP, U) JP-A 58-27575 (JP, U) JP-A 59-104 43668 (JP, U)

Claims (4)

(57) [Claims] 1. A nozzle body having an injection hole and a valve seat upstream of the injection hole, a valve body opening and closing a fuel passage between the nozzle seat, and a valve body disposed upstream of the valve seat. And, a fuel injection valve comprising an element for forming a fuel passage that gives a swirling force to the supplied fuel, the outer shape of the element viewed from the valve axis direction is formed in a polygonal shape,
The plane portion of the outer periphery of the polygonal shape and the inner wall surface of the nozzle body constitute an axial fuel passage, and are connected to the axial fuel passage, and the surface of the element on the valve seat side with respect to the valve shaft center. A radial fuel passage that is eccentric is formed, the inlet of the radial fuel passage is shifted to an end side from the circumferential center of the flat portion, and the cross-sectional area of the radial fuel passage is defined by the injection hole. A fuel injection valve having a larger cross-sectional area. 2. A nozzle body having an injection hole and a valve seat upstream of the injection hole, a valve body opening and closing a fuel passage between the valve seat, and a nozzle body disposed upstream of the valve seat. And an element for forming a swirl passage for applying a swirling force to the supplied fuel, wherein the element is arranged in a direction along an axis from an upper end to a lower end of an outer peripheral surface thereof, and A plurality of axial fuel passage surfaces formed at intervals in the circumferential direction of the outer peripheral surface, and a fuel passage extending in a direction along the axis using the axial fuel passage surface and the inner wall surface of the nozzle body; A fuel passage in a radial direction that applies a turning force to the fuel is connected to a lower end of the fuel passage, and an inlet of the fuel passage in the radial direction is closer to an end side than a circumferential center of the fuel passage surface in the axial direction. Stagger,
An electromagnetic fuel injection valve, wherein a cross-sectional area of a radial fuel passage is larger than a cross-sectional area of the injection hole. 3. The fuel injection valve according to claim 1, wherein the radial fuel passage is formed by a groove formed on a surface of the element on the valve seat side. . 4. A fuel injection valve according to claim 1, wherein said radial fuel passage comprises a plurality of fuel passages, and said radial fuel passage has a cross-sectional area of said plurality of fuel passages. A fuel injection valve having a total sectional area of a passage.