JPH01267353A - Electromagnetic type fuel injection valve - Google Patents

Abstract

PURPOSE:To prevent the occurrence of solid friction of a moving part and to stabilize behavior of a ball valve at each injection time, by a method wherein, in an electromagnetic type fuel injection valve in which a ball valve and a moving segment form a moving part, a tapered gap is provided between the moving segment and the inner periphery of a yoke for guiding the moving segment. CONSTITUTION:With a coil 13 energized, a magnetic circuit is formed with a core 3, a yoke 2, and a moving segment 4, and the moving segment 4 is attracted to the core 3 side against a spring 10. When, as noted above, the moving segment 4 is lifted, a ball valve 6 formed with the moving segment is also lifted and separated away from a valve seat 8, and fuel is injected through an injection nozzle 7. In this case, the moving segment 4 of moving part (4, 6) A is guided by a guide part B situated to the bottom part of the yoke 2, and the moving segment 4 is formed in a taper shape such that a gap on the ball valve 6 side between the moving segment and an inner periphery B of the yoke is wide and the gap on the coil 13 side therebetween is narrow. Fed fuel after passing through the gap is guided out to a reservoir through a drain port 32.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to electromagnetic fuel injection valves used in engines such as automobiles, and is particularly applicable to improving control accuracy and reliability in the small injection voltage range. The present invention relates to the structure of a suitable electromagnetic fuel injection valve.

[Conventional technology]

The conventional ball valve type electromagnetic fuel injection valve was developed in Japanese Patent Application Laid-open No. 5
As described in No. 7-28861, the ball valve and the movable element are integrated with a stem to form the movable part, and the guide during operation of the movable part is a low-friction material in which the outer periphery of the movable element is provided on the inner periphery of the yoke. It was supposed to be guided and centered using a guide ring.

[Problem to be solved by the invention]

Although the above-mentioned prior art is effective in centering the mover and reducing solid friction between the mover and its guide, the solid friction between the mover and its guide cannot be reduced to zero. This becomes a factor that greatly affects the behavior of the ball valve in the small pulse ms region where the injection amount is very small. As a result, there is a problem in that stable control of the injection amount cannot be obtained in a small injection amount region.

The purpose of the present invention is to improve control accuracy of injection amount in a small injection amount region, simplify the structure, and improve the accuracy of injection amount control in an electromagnetic fuel injection valve whose movable parts are a ball valve, a mover, and a stem that connects these together. The objective is to improve durability and reliability.

[Means to solve the problem]

The above purpose is to form a flow path so that high-pressure fuel is guided only to the valve body in an electromagnetic fuel injection valve whose movable parts are a ball valve, a mover, and a stem that connects these, and to guide the mover. The gap between the outer circumference of the mover and the inner circumference of the yoke is tapered, and the taper is such that the gap on the valve body side is large and the gap on the opposite side (core side) is small. This is achieved by having a structure in which the fuel is passed from the body side to the core side, and the passed fuel is finally led to the drain port connected to the reservoir.

[Effect]

In the above structure, when the movable element is subjected to a disturbance that causes the centers of the movable element and the yoke to shift due to the flow of fuel into the tapered gap between the movable element and the inner periphery of the yoke, it is possible to A centering force is applied to return it to . 70 Force F is here d: Yoke inner diameter % t: Taper gap guide length, Δp: Fuel differential pressure before and after the taper gap.

hl: Radial clearance of how to handle taper clearance, h2: Radial clearance of wider taper clearance.

F becomes the maximum value F IQ &
...(3). In addition, the centering force of about 90% or more of F□ is 1.3<λ<3 as shown in Figure 3.
You can get it. Therefore, 163×λ<3. λ to ideal V
If you create a taper gap between the movable element and the guide part on the inner circumference of the yoke to obtain a diameter of 1.83 mm, and apply a differential pressure there.

Since the force 0.9 to 1 times F□8 in equation (3) always acts on the mover as a centering force, the external force Fd that acts on the mover and tends to cause center deviation is
a (If 0,9F rna Since there is a line contact between the valve and the seat, solid friction is basically always eliminated when driving the ball valve.From the above explanation, 'I!l magnetic fuel tilting type fuel injector pulse signal. For example, even if a minute pulse width signal is input,
Since the influence of solid friction of the moving parts is eliminated, stable behavior is obtained, and the injection amount for each injection can be controlled with precision without variation, improving stability. Furthermore, the structure is simplified by eliminating the need for the low-friction material conventionally provided on the inner periphery of the yoke, and the solid friction of the movable parts can be eliminated, improving the durability and reliability of the movable parts.

〔Example" An embodiment of the present invention will be described below with reference to FIG.

The magnetic circuit of the electromagnetic fuel injection valve 1 includes a cylindrical yoke 2 with a bottom.
, which closes the open end of the yoke 2 and consists of a core 3 of a columnar stopper extending to the center of the yoke 2, and a mover 4 facing the core 3 with a gap in between. A movable element 4 is located at the center of the columnar part of the core 3.
A hole is made for inserting and holding a spring 10 as an elastic member for pressing the movable part A, which is fixedly heated by a stem 5 and a ball valve 6, against a seat part 9 of a valve seat 8 having a fuel injection lower part. It is. The upper end of the spring 10 is in contact with the lower end of an adjuster 11 inserted through the center of the core 3 in order to adjust the set load t which presses the ball valve 6 against the seat part 9. An O-ring 12 is provided between the core 3 and the adjuster 11 to prevent fuel from leaking to the outside. A coil 13 that excites the magnetic circuit is wound around a bobbin 14. The terminal 16 of the coil assembly 15 consisting of these is inserted into a hole 17 provided in the collar of the core 3, and an O-ring 18 is inserted between the terminal 16 and the core 3.

A collar 19 covering the entrance of the hole 17 is provided to prevent the mold resin 20 on the outside of the electromagnetic fuel injection valve 1 from entering the inside of the electromagnetic fuel injection valve 1 during molding. A gap 21 serving as a flow path between the core 3 and yoke 2 and the coil assembly 15 as a passage for fuel or fuel vapor;
22, 23° and 24 are provided. Annular grooves 25, 26, and 27 are formed on the outer periphery of the yoke 2 and the valve seat 8, and are used to connect the electromagnetic fuel injection valve 1 and a socket (as a housing).
O-ring 2 to prevent fuel leakage from the gap between the
8, 29.30 is holding there. An inlet port 31 through which fuel flows and a drain port 32 through which excess fuel is returned to a reservoir (not shown) are opened around the yoke 2. Further, a guide portion B for guiding the movable element 4 of the movable portion A is provided in the bottomed portion of the yoke 2. This guide portion B has a cylindrical shape that is coaxial with the movable element 4 and slightly larger than the outer diameter of the movable element 4. The outer shape of the movable element 4 guided here is tapered as will be described in detail later. Furthermore, in the bottomed part of yoke 2.

Stopper 33. A valve seat receiving portion 34 for receiving a valve seat 8 is provided over the tip 1 of the yoke 2.

A terminal 16' is connected to the terminal 16 for transmitting a signal from a control unit (not shown) to the coil 13.

These terminals are molded with a molding resin to form a molded connector 20'.

The electromagnetic fuel injection valve 1 formed in the above structure normally has the following characteristics:
The compressive force of the spring 10 presses the υ Hall valve 6 against the seat part 9 and closes it, but the movable part A is operated by an electric on/off signal given to the coil 13 to open and close the valve seat. and thereby inject the fuel.

The electric signal is given as a pulse to the coil 13, and the pulse width is determined by the control unit depending on the amount of injection per injection. When a current is passed through the coil 13, the core 3. York 2. A magnetic circuit is constituted by the movable element 4, and the movable element 4 is attracted to the core 3 side against the spring force of the spring 10. When the mover 4 lifts, the ball valve 6 integrated with it also lifts, and the valve seat 8
The ball valve 6 is separated from the seat portion 9, creating an opening.

Fuel flows in here and flows out as a fuel injection rowanizi jet. In detail, the pressure of the fuel is regulated by a fuel pump and a fuel pressure regulator (not shown).

Inflow port 3 from Tsuyuel gear through socket 11
1, the stain flows into the inside of the magnetic fuel injector assembly 1 and fills the gap 35 between the stopper 33 and the stem 5. Outer part 3 of ball valve 6
6, the fuel is supplied to the opening of the seat portion 9, and is injected into the intake pipe of the engine from the fuel injection lower when the valve is opened. When the ti signal to the coil 13 is turned off and the electromagnetic attraction force acting on the movable element is deenergized, the movable element is pushed by the spring 10,
The ball valve 6 is pressed against the seat portion 9 to close the opening.

In these series of operations, the movable part A is always guided by the inner circumference B of the yoke. The fuel that has flowed into the inflow port 31 passes through a narrow tapered gap provided between the movable element 4 and the inner periphery of the yoke B, flows toward the coil 13, and finally flows from the drain port 32 to the reservoir. FIG. 2 is a partially enlarged view of the movable part A and the inner circumference B of the yoke in FIG. 1.As shown in FIG.
It has a tapered shape with a large gap with the yoke inner circumference B on one side and a small gap with the yoke inner circumference B on the opposite side (coil side). As shown in Fig. 2, the former gap k
hz *When the latter gap is hl, the above (1)
Since the formula (3) holds true, the centering force F is always acting on the mover 4. And the ratio λ of h2 and hl is 1.3<λ<3. It is desirable to select λ=1.83 if possible. here.

Even if an external force Fa that tries to cause center shift of the mover 4 occurs due to the screw thread of the spring 10 or the dimensional accuracy error of the parts of the movable part A, if F is set to be greater than Fd, it will not occur in any case. Also, since the movable element 4 can maintain a fluid lubricated state without making solid contact with the inner periphery of the yoke B, no solid friction occurs between the movable parts. Therefore, even when the magnetic attraction force acting on the movable element 4 is weak, such as in the case of a minute pulse width signal, the behavior of the ball valve 6 remains stable without changing for each injection. The same holds true even when the pulse width becomes large. Moreover, this improves the control accuracy of the injection amount, simplifies the structure, and improves the durability and reliability of the movable member.

4 and 5 show other embodiments of the present invention,
Components that are the same as those in FIG. 1 are designated by the same reference numerals. FIG. 4 shows an electromagnetic fuel injection valve according to the present invention having a valve seat 8' having a plurality of flow passages 37 provided on the upstream side of the seat portion 9 of the ball valve 6 by shifting the center of the ball valve for fuel swirling. An example is shown below. Figure 5 is.

For fuel swirling on the downstream side of the seat portion 9 of the ball valve 6.

A rotating piece 39 has a plurality of fuel injection lowers' which are penetrated at a certain angle with respect to the core of the ball valve 6 on the same circumference and a cylindrical hole 38 that guides the injected fuel from the fuel injection lowers'. An example in which the present invention is implemented in an electromagnetic fuel injection valve having a fixed valve guide f will be shown. The effect is the same in either case.

Note that the present invention does not limit the fuel passage controlled by the ball valve.

〔Effect of the invention〕

According to the present invention, since there is no solid friction in the moving parts of the ball valve electromagnetic fuel injection valve, the behavior of the ball valve for each injection is stabilized, and the control accuracy and stability of the injection amount for each injection are improved. At the same time, the structure is simplified and the durability and reliability of the movable member are improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a magnetic fuel injection valve '1 according to an embodiment of the present invention, Fig. 2 is a partially enlarged view of A and H in Fig. 1, and Fig. 3 is a line showing the relationship between λ and F. 4.5 are sectional views of electromagnetic fuel injection valves according to other embodiments of the present invention. 1... Electromagnetic fuel injection valve, 2... Yoke, 3...
core. 4... Mover, 6... Ball valve, 7... Fuel injection port, 8... Valve seat, 10... Spring, 13...
・Coil, 31...Inflow port, 32...Drain port% 33...Stopper, A...Movable part, B...
- Inner circumference of the yoke.゛. No. 1 Lower, Po: Feeding mouth 2nd mouth 3rd mouth 8 ・-Help ``Seat Day'' Seat part 37...Shi front dew hole 39 Shiba base bead

Claims (2)

[Claims] 1. A stator core made of a magnetic material inserted through the center of a ring-shaped electromagnetic coil, a ring-shaped mover made of a magnetic material provided facing the tip of this stator core, and a spherical shape attached to the tip of this mover. a yoke made of a magnetic material that constitutes a magnetic circuit together with the valve body, stator core, mover, and electromagnetic coil; and elastic means for biasing the movable member consisting of the valve body and the mover in a direction away from the stator core. When the electromagnetic coil is energized, the magnetic attraction force generated between the stator core and the movable element overcomes the biasing force of the elastic means and strokes the valve body, causing the fuel to flow. In a device that has a high-pressure fuel supply port adjusted to a constant pressure in the valve body with the outlet port open between them, a flow path is formed so that the high-pressure fuel is led only to the valve body, and the guide of the mover is guided by a yoke. This is done only on the inner circumference, and the gap between the outer circumference of the mover and the inner circumference of the yoke is tapered.The taper makes this gap on the valve body side larger and the gap on the opposite side (core side) smaller, and the supplied fuel passes through this gap. An electromagnetic fuel injection valve characterized in that the fuel injection valve is then guided to a drain port connected to a reservoir. 2. In the device described in claim 1, the tapered gap between the outer circumference of the mover and the inner circumference of the yoke is defined as h_2 for the radial gap on the valve body side and h_1 for the radial gap on the opposite side (core side).
Then, the ratio λ of h_2 and h_1 (=h_2/h_1
) is set to 1.3<λ<3.