JPH02215963A - Solenoid-controlled fuel injection valve - Google Patents

Abstract

PURPOSE:To secure an injection fuel quantity as well as to facilitate the work of a fuel injection valve by installing a ring fuel swirling force generating element where plural numbers of fuel passage grooves are set up, and setting an interval between an inner diameter of this element and an outer diameter of a valve body to a specified dimensional relationship. CONSTITUTION:A fuel swirling force generating element 12 is fixedly set up at the upstream side of a valve seat 11. An inner diametral part of this generating element 12 guides the axial movement of a ball valve 14. Plural numbers of fuel passage grooves 13 are set up over one end face directed to the side of the valve seat 11 from the outer diametral part. A relationship of D - d <=0.028mm is set so as to be realized in an interval between an inner diameter phiD of this generating element and an outer diameter phid of the said valve body. Thus, secureness of a request injection fuel quantity is promoted, so that facilitation for the work of a fuel injection valve and reduction in cost can be all promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic fuel injection valve used to supply fuel to an engine, and more specifically, the present invention relates to an electromagnetic fuel injection valve that is used to supply fuel to an engine, and more particularly, it relates to an electromagnetic fuel injection valve that applies a swirling force to the fuel on the upstream side of the valve seat. This invention relates to the structure of an upstream swirl type electromagnetic fuel injection valve.

[Conventional technology]

For m-magnetic fuel injection valves used in automobile engines, various techniques have been proposed to atomize the fuel in order to improve mixture formation. Typical methods for fuel atomization include installing a tip at the tip of a needle valve to cause the injected fuel to collide, or applying swirling force to the fuel to inject it in a liquid film to promote fuel atomization. There is something. this house,
The latter is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-35169.

As disclosed in Japanese Unexamined Patent Application Publication No. 61-232378, there is a downstream swirl system in which a swirl orifice is provided on the downstream side of a valve seat to inject fuel while applying swirling force to the fuel.

More recently, as an alternative to the downstream swirl type, an upstream swirl type electromagnetic fuel injection valve has been proposed in which a fuel swirl force generating element (swirler) is disposed immediately upstream of the valve seat.

Fig. 7 is a basic structural diagram of the upstream swirling system, where 1° is the nozzle body, 11 is the valve seat formed on the nozzle body, and 12 is the annular fuel swirling force generating element provided immediately upstream of the valve seat. The turning force generating element 12 has a valve body (ball valve) 14 introduced into its inner diameter, guides the movement of this valve body in the axial direction, and has a plurality of grooves extending from the outer diameter to the end face facing the valve seat. Fuel passage $1
3 is formed. One surface of the fuel passage groove 13 is connected to the nozzle body 1
0 to form a passageway.

The ball valve 14 is connected to a plunger (not shown) via a rod 15, and is urged toward the valve seat 11 by a return spring (not shown), so that the plunger and ball valve 14 resist the force of the return spring by electromagnetic force. Since the fuel passage groove 13 is arranged eccentrically with respect to the center of the fuel swirling force element, the fuel that has passed through the fuel passage groove 13 will be sucked into the ball valve 14.
The orifice 10a rotates along the plane of the
is injected to the outside of the injection valve.

The spread angle of the fuel when injected into the atmosphere is determined by the eccentricity l of the fuel passage groove 13 with respect to the center #I of the fuel swirling force generating element (center of the ball valve), and the larger the eccentricity 1, the wider the spread angle becomes. growing.

This divergence angle varies depending on the applied engine system, and for multipoint fuel injection (MPI) systems.

15°~25@, 5 for single point fuel injection (SPI) system
5' to 65° is common. The specific amount of eccentricity is sp
In the r system, the eccentricity 1 is set to such an extent that the fuel passage groove 13 approaches the tangent to the inner circumference of the fuel swirling force generating element 12, whereas in the MPI system, the eccentricity 1 is set to the extent that the fuel passage groove 13 approaches the tangent to the inner circumference of the fuel swirling force generating element 12. It belongs to

Note that this upstream swirling method is evaluated as being effective in atomizing fuel.

[11g to be solved by the invention] By the way, when adopting such an upstream swirling method, in order to improve performance, it is necessary to improve the fuel spray characteristics (spray angle, atomization).
In addition to this, it is also essential to ensure the required fuel injection amount. Among these factors, there are the following factors that inhibit the required fuel injection amount.

The first problem is that it interferes with the reproducibility of the required fuel amount when repeated fuel injections are performed, and this has occurred because the first-order point has not been sufficiently considered.

That is, in developing the upstream swing type injection valve, the present inventors investigated the causes of variations in the amount of repeated fuel injection, and found that this tendency was particularly large in the MPI type with a small spray bed angle. As a result, it was found that this occurs when the axial flow energy generated between the outer diameter of the ball valve 14 and the inner diameter d of the fuel swirling force generating element 12 is larger than the swirling energy. What influences this axial flow energy and swirling energy is the clearance G between the outer diameter of the ball valve 14 and the inner diameter d of the fuel swirling force generating element 12. The larger the clearance G, the more the flow passes through this clearance. When the axial flow component increases and exceeds a certain limit, the axial flow energy becomes larger than the swirl energy formed by the passage groove of the fuel swirl force generating element. In particular, MPI
As in the method, the eccentricity l of the fuel passage groove 13 is reduced,
This phenomenon becomes noticeable when the turning force is suppressed. When such a phenomenon occurs, the ball valve 14 loses its centering function given by the swirling force during the swirling motion and swings, causing any abutting motion against the inner wall surface of the fuel swirling force generating element 12. It will be repeated. In this case, the loss ratio of the swirling motion and the axial motion is different between when the outlet of the fuel passage groove 13 is abutted to block it and when it is abutted so as not to be obstructed, so that the fuel injected from the nozzle 10 This results in variations in the amount of fuel injection, resulting in a decrease in the reproducibility of the fuel injection amount. In other words, such a phenomenon causes the flow coefficient of the orifice 10a to become unstable, thereby reducing fuel reproducibility.

The second problem is caused by the shape accuracy of the fuel swirling force generating element, and in this case, if the accuracy is poor, the required amount of fuel cannot be secured from the beginning.

To explain this with reference to FIG. 5, (a) in FIG. 5 shows the relationship between the eccentricity l of the fuel passage groove formed in the fuel swirling force generating element, the injection amount and the spray angle 9, and (b) the relationship between the particle diameter. The relationship between the depth of the fuel passage groove and the injection amount.

(c) shows the relationship between the groove width of the fuel passage groove and the injection amount.

As shown in Fig. 5 (a), (b), and (c), the injection amount characteristics of the fuel injected by the electromagnetic fuel injection valve are greatly influenced by the eccentricity l of the groove of the fuel swirling force generating element, and the groove width , the influence of groove depth is small, and this influence also appears in the spray characteristics of electromagnetic fuel injection valves.

Therefore, it is desirable that the eccentricity 1 of the groove of the fuel swirling force generating element be uniform. In order to meet this shape accuracy, it is necessary to use a material with good processing accuracy. By the way, a common method for forming such a grooved fuel swirling force generating element is to use cutting, but there is a problem in terms of processing accuracy, and it is difficult to maintain uniformity in the amount of eccentricity l. This is difficult and involves multiple steps such as lathes and plies, and a great deal of time is spent removing the burr generated at the corners of the turning force generating element.

The present invention has been made in view of the above points, and its main purpose is to secure the required amount of injected fuel, which is a problem with upstream swirl type electromagnetic fuel injection valves, and also to achieve this goal. The object of the present invention is to improve the ease of processing and reduce costs of electromagnetic fuel injection valves.

[Means to solve the problem]

In order to solve the above-mentioned object, the present invention provides, as a first problem-solving means, an electromagnetic coil including a core, a plunger with a valve body inside an injection valve body, and the plunger and the valve body placed on the valve seat side. In an electromagnetic fuel injection valve of a type in which a biasing return spring or the like is incorporated, and the plunger is reciprocated by the force of the excitation and de-excitation of the electromagnetic coil and the return spring to open and close the valve body, Immediately upstream of the valve seat, there is an annular fuel swirling force generating element, the inner diameter of which guides the axial movement of the valve body, and the outer diameter of which guides the fuel to the end face closer to the valve seat. An annular fuel swirling force generating element in which a plurality of fuel passage grooves eccentric with respect to the center of the inner diameter portion are disposed is disposed on the near end face, and an inner diameter φD of the fuel swirling force generating element and the valve body, Outer diameter φd
The relationship is set such that D-d≦0.028 mm.

Further, as a second means for solving the problem, a fuel swirling force generating element similar to the first means for solving the problem is formed by a sintered member or a cold forged product based on stainless alloy steel.

[Effect]

According to the first problem solving means, the outer diameter φD of the valve body and the inner diameter φd of the fuel swirling force generating element in the upstream swirl type solenoid valve.
By reducing the clearance between the outer diameter of the valve body and the inner diameter of the fuel swirling force generating element by setting the relationship between
(approximately 0 mm), the axial flow kinetic energy of the fuel flowing through the clearance can be reduced to about 1/2 compared to the conventional one.

According to the experimental results, by satisfying the above relational expression, the swirling kinetic energy created by the fuel passage groove (eccentric groove) formed in the fuel swirling force generating element is always larger than the axial flow kinetic energy. The results were obtained.

This swirling flow flows along the lower surface of the valve body, exerting a good floating effect on the valve body, and as a result, each fuel swirling flow flowing out from each fuel passage groove is balanced, and these swirling flows are balanced. The swirling flow centers the valve body. As a result, the vibration of the valve body is eliminated,
When the valve is open, the valve body always maintains its proper position, so that the valve body does not block the fuel passage groove, and by maintaining an appropriate annular clearance between the valve body and the valve seat, the flow rate of fuel to the metering orifice is reduced. By stabilizing the coefficient, repeatability of fuel injection is guaranteed, and the required fuel amount can always be secured.

According to the second means for solving the problem, the fuel swirling force generating element is formed from a sintered member or a cold forged product based on stainless alloy steel, but in this case, the processing of the fuel swirling force generating element is What are the points to keep in mind?

It is limited only to the eccentricity l of the fuel passage groove. Since this fuel passage groove has a simple structure, it can be formed easily and with high precision mainly by cold forging.

In addition, since it can be processed mainly by cold forging and does not require cutting, it prevents the occurrence of harmful burrs and burrs caused by cutting operations. By improving the machining accuracy of the fuel swirling force generating element in this way, the uniformity of the eccentricity l of each fuel passage groove formed therein can be maintained, and the fuel spray characteristics (spray angle 9 particle diameter) can be maintained. In addition, by maintaining the uniformity of the eccentricity l when multiple fuel passage grooves are formed in the fuel swirling force generating element, the fuel flowing out from each fuel passage groove generates a balanced swirling force. As a result, the valve body can exhibit a good centering function, and the required injection amount characteristics can be improved by stably operating the valve body.

In addition, for the downstream turning method, for example, Japanese Patent Application Laid-Open No. 61-23237
As disclosed in Public Letter No. 8, the fuel swirling force generating element is formed of a sintered part, but in the case of the downstream swirling method, the fuel swirling mechanism part and the fuel metering part have an integrated structure. , since it has an orifice, cold forging and cutting are required as machining steps, which increases the machining cost. Further, in the case of hot forging, there is a problem that the accuracy of the eccentricity l of the fuel passage groove cannot be ensured due to thermal distortion.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a perspective view of the fuel swirling force generating element used in this embodiment. Incidentally, in these drawings, the same reference numerals as those in FIG. 7 described above indicate the same or common elements.

In FIG. 1, 1 is a yoke that becomes the main body of the injection valve, and a core 2. A coil assembly 4 consisting of an electromagnetic coil 3 and the like is fixedly installed inside. Reference numeral 5 designates a plunger, to which a ring 6 is attached to one end and a rod 15 is integrally coupled to the other end by coupling utilizing plastic flow, welding, tension coupling, or the like. Furthermore, the ball valve 14 is integrally connected to the tip of the rod 15 by welding. Further, the plunger 5 is installed inside a fuel passage 7 provided in the central shaft of the injection valve body 1 along the axial direction.

It is arranged in the same direction as the core 2. A portion of the ring 6 is slidably fitted to the inner periphery of one end of the core 2.

A return spring 9 is interposed between the inner periphery of one end of the plunger 5 and the screw force *a rod 8 in the core 2.

A nozzle body 10 is attached to the lower end of the yoke 1. The nozzle body 10 has a cylindrical shape, a valve seat 11 is formed inside the nozzle body 10, and a fuel injection port 10a is disposed downstream of the valve seat 11.
On the other hand, a fuel swirling force generating element 12 is fixedly disposed upstream of the valve seat 11.

The fuel swirling force generating element 12 has a top-shaped annular body, and a ball valve 1 is provided on the inner diameter part (inner periphery) of the annular body 12.
4 is introduced so as to be reciprocatably guided in the axial direction. Further, a plurality of fuel passage grooves 13 are provided from the outer diameter portion (outer periphery) of the annular body 12 to one end surface facing toward the valve seat 11 (end surface closer to the valve seat). As shown in FIG. 2, this fuel passage groove 13 is eccentric by one minute with respect to the central axis of the fuel swirling force generating element 12, and the negative surface of the passage groove 13 is covered with the inner surface of the nozzle body 10. to form a passage.

The outlet of the fuel passage groove 13 is positioned so as to face the lower surface of the ball valve 14 from the center thereof when the ball valve 14 is in contact with the valve seat. 3 and 4 show other examples of the fuel swirling force generating element 7-12, and in FIG. 3,
Four flat surfaces 12a are formed on the outer diameter portion of the annular fuel swirling force generating element 12.

The space formed by this flat surface 12a and the inner peripheral surface of the nozzle body 10 forms a fuel passage space, and the groove itself is formed only on the end face closer to the valve seat. In FIG. 4, an L-shaped notch surface 12b is formed on the outer diameter portion of the fuel swirling force generating element 12, and this notch surface 12b and the inner periphery of the nozzle body 10 secure a fuel passage space.

Reference numeral 16 denotes a stopper for regulating the amount of movement of the ball valve 14, and is arranged at the upper part of the nozzle body 10.

Reference numeral 17 indicates a fuel supply hole formed in the yoke 1.

Next, the operation of this embodiment will be explained.

By controlling the energization of the electromagnetic coil 3 via the connector 18 according to the determined on/off duty, l
! When the electromagnetic coil is energized and de-energized and the electromagnetic coil 3 is energized, the coil 3. Core 2. York 1. A magnetic circuit is formed by the plunger 5, and the ball valve 14 and the plunger 5 are magnetically attracted to the core 2 side. As a result, an annular flow path (small gap) is secured between the ball valve 14 and the valve seat 11, and the valve is in an open state.

Then, the fuel passes through the fuel pipe 20, from the fuel supply hole 17 on the outer periphery of the yoke to the fuel passage 19 between the outer periphery of the coil assembly 4 and the inner periphery of the yoke 1. The fuel passes through the central passage 7, the fuel passage groove 13 formed in the fuel swirling force generating element 12, and flows out to the inner peripheral side of the fuel swirling force generating element. As a result of this spill, the fuel
Since the passage groove 13 is eccentric, it flows along the outer periphery of the lower surface of the ball valve while swirling, passes through the valve seat 11, and is sprayed at a spray angle determined by the swirling force while being metered by the orifice 10a. .

When performing such a fuel injection operation, the ring 6 guides the movement of the plunger 5, and the inner circumference of the fuel swirling force generating element 12 guides the movement of the ball valve 14.

In this embodiment, the difference between the inner diameter φD of the fuel swirling force generating element 12 and the outer diameter φd of the ball valve 14 is set to D−d≦0.
By setting it to 028 mm, the following actions and effects occur.

That is, as stated in the problem to be solved by the invention, there is an axial flow component in which the fuel flows without swirling in the clearance (D-d), and this axial flow component becomes larger as the clearance becomes larger. If this clearance becomes large, it becomes a factor that deteriorates the reproducibility of the required fuel injection amount, as shown in FIG.

In this example, we experimentally determined how to set the clearance (D-d) to maintain good fuel injection reproducibility, and
Figure J46 shows the results of this experiment.

In this experiment, the reproducibility of fuel injection is expressed as Δq. The absolute amount of static flow is the difference between the maximum flow rate measurement value and the minimum flow rate measurement value when measuring the fuel injection amount 10 times.
5cc/min], clearance (D-d)
The reproducibility Δq is 2 a c at 0°Q28mm or less
/ min or less, and the injection amount (1
85cc/m1n), it satisfies the target value of 2% or less.

That is, by setting D-d≦0.028 mm, the flow of the axial flow is reduced, and by flowing most of the fuel toward the passage groove 13 side of the fuel swirling force generating element, the axial flow energy is converted into swirling energy. Since it can always be made smaller than the
The ball valve 14 is centered by the even floating effect of the swirling flow from the lower surface side, and as a result, the annular shape between the ball valve 14 and the valve seat 11 that is formed when the valve is opened can be maintained without blocking the fuel passage groove 13. By maintaining the gap in a stable state, the flow coefficient of the orifice can be stabilized and the reproducibility of the fuel injection amount can be improved.

Further, in this embodiment, the fuel swirling force generating element 12 is formed of a sintered member or a cold forged product based on stainless alloy steel. Among these, as the sintered member, one based on a nickel-iron alloy is used.

When such a cold forged product is used, it has the following advantages.

That is, the fuel swirling force generating element 12 is constituted by an annular body and has a simple structure in which an eccentricity s13 for generating the swirling force is formed on the outer surface of the annular body, so that it can be manufactured only by press forming mainly by cold forging. possible, requires less processing time,
Moreover, the only thing to keep in mind during machining is the eccentricity of the fuel passage groove (1), and when this groove is formed by press working, it can be formed more easily and with higher precision than by cutting.

C. Effects of the Invention] As described above, according to the present invention, in the first means for solving the problem, the upstream The swirling energy of the fuel swirling force generating element used in the swirling system can always be stably larger than the axial flow energy, improving the reproducibility of the fuel injection amount. By improving the accuracy of the eccentricity of the fuel passage groove and improving the fuel injection amount characteristics, the required fuel injection amount can be ensured by these problem-solving means.

Furthermore, in the second problem-solving means, the fuel swirling force generating element can be easily machined and the number of machining steps can be reduced, thereby reducing the machining cost.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is a perspective view of a fuel swirling force generating element used in the above embodiment, and FIGS. 3 and 4 are other illustrations of the fuel swirling force generating element. A perspective view showing an example, FIG. 5 shows the amount of eccentricity of the fuel passage groove of the fuel swirling force generating element,
A characteristic diagram showing the relationship between the groove depth and vibration amplitude and the injection amount. Figure 6 shows the reproducibility showing the relationship between the amount of fuel amount fluctuation and the difference between the inner diameter of the fuel swirling force generating element and the outer diameter d of the valve body. The characteristic diagram, FIG. 7, is a principle diagram of the upstream turning system to which the present invention is applied. DESCRIPTION OF SYMBOLS 1... Injection valve body, 2... Core, 3... Electromagnetic coil, 4... Coil assembly, 5... Plunger,
9... Return spring, 10... Nozzle body, 10a...
Orifice, 11... Valve seat, 12... Fuel swirling force generating element, 13... Fuel passage groove (eccentric groove) 14... Valve body (ball valve), 15... Rod. Cumulative 4-mouth (b) (c)

Claims (2)

[Claims] 1. An electromagnetic coil including a core, a plunger with a valve body, a return spring that biases the plunger and the valve body toward the valve seat, etc. are installed inside the injection valve body, and the electromagnetic coil is energized, de-energized, and returned. In an electromagnetic fuel injection valve of a type in which the plunger is reciprocated with a force of 1 to 1 to open and close the valve body, an annular fuel swirling force generating element is provided immediately upstream of the valve seat, and the inner diameter The outer diameter part guides the axial movement of the valve body, the outer diameter part guides the fuel to the end face closer to the valve seat, and the end face closer to the valve seat is provided with a plurality of fuel passage grooves eccentric to the center of the inner diameter part. An annular fuel swirling force generating element is disposed, and the relationship D-d≦0.028 mm is established between the inner diameter φD of the fuel swirling force generating element and the outer diameter φd of the valve body. An electromagnetic fuel injection valve characterized by being configured. 2. An electromagnetic coil including a core, a plunger with a valve body, a return spring that urges the plunger and the valve body toward the valve seat, etc. are installed inside the injection valve body, and the electromagnetic coil is energized, de-energized, and returned. In an electromagnetic fuel injection valve of a type in which the plunger is reciprocated with a force of 1 to 1 to open and close the valve body, an annular fuel swirling force generating element is provided immediately upstream of the valve seat, and the inner diameter The outer diameter part guides the axial movement of the valve body, the outer diameter part guides the fuel to the end face closer to the valve seat, and the end face closer to the valve seat is provided with a plurality of fuel passage grooves eccentric to the center of the inner diameter part. An electromagnetic type, characterized in that an annular fuel swirling force generating element is disposed, and the fuel swirling force generating element is formed of a sintered member or a cold forged product based on stainless alloy steel. fuel injection valve.