JPH0370863A - fuel injector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injector that can adjust the fuel injection state according to the driving conditions of a vehicle.

[Conventional technology]

As a conventional fuel injector, one shown in FIG. 8 is known.

In the figure, 1 is an injector main body (hereinafter referred to as "main body 1"), and the main body l includes a large diameter cylindrical part IA formed at its base end side (upper end side in the figure), and a large diameter cylindrical part IA formed on the base end side (upper end side in the figure). The tip side (
It consists of a small diameter cylindrical part IB integrally formed with a large diameter cylindrical part IA (lower end side in the figure), and a reduced diameter part IC formed between them. Reference numeral 2 denotes an injection nozzle fitted and fixed in the small diameter cylindrical portion IB of the main body 1;
A large-diameter base 2A that is directly fitted into the inside of the main body 1 and fixed to the main body 1 by caulking the tip of the small-diameter cylindrical portion IB, and the base 2
A valve cylinder part 2B is provided integrally with A and extends toward the distal end side, a fuel passage 2C is provided passing through the base part 2A and the valve cylinder part 2B upward and downward, and the fuel passage 2C
The fuel injection port 2D is comprised of a fuel injection port 2D serving as an outlet, and a valve seat 2E provided on the inner upper surface of the injection port 2D. In addition, 3 is an O-ring that seals between the small diameter cylinder part 1B and the base 2A, 4 is a resin protector that is fitted and fixed to the valve cylinder part 2B, and 5 is formed in a U-shape or C-shape. The stoppers fixedly supported together with the base portion 2A within the small-diameter cylindrical portion IB are shown.

Reference numeral 6 denotes a needle valve that is slidably inserted into the fuel passage 2C of the injection nozzle 2 while allowing the flow of fuel. In this order, a diameter-enlarged proximal end portion 6A fixedly supported by an anchor 15, which will be described later, and a lower portion of the stopper 5 are formed to have an enlarged diameter, and by coming into contact with the stopper 5, the amount of displacement of the needle valve 6 is regulated. 2 in the fuel passage 2C.
□Sliding contact steps 6C, 6C are provided at the axial tip portion and are provided in sliding contact with the inner circumferential surface of the fuel passage 2C to support the reciprocating movement of the needle valve 6 and allow the passage of fuel, It is composed of a contact surface 6D that opens and closes the valve by applying pressure to and from the valve seat 2E, and a pintle shaft 6E that protrudes from the tip end in the axial direction.

Reference numeral 7 denotes an electromagnetic actuator housed in the large-diameter cylindrical portion IA. It is generally composed of a wound coil 10. Here, the core member 8 is the main body 1
The flange portion 8A is caulked and fixed to the base end of the large diameter cylindrical portion 1A.
, an extending portion 8B formed extending upwardly on the upper side (base end side) of the flange portion 8A, a core portion 8c formed extending downwardly (distal end side) of the flange portion 8A, and a flange It is composed of a portion 8A, an extending portion 8B, and a communication hole 8D provided to pass through the core portion 8C in an upward and downward direction, and the core portion 8C
The coil bobbin 9 is provided on the outer periphery. In addition,
11 is a fuel vibrator press-fitted into the communication hole 8D; 12;
゜13 is provided above and below the coil bobbin 9, and between the coil bobbin 9 and the outer peripheral surface of the core portion 8C and between the coil bobbin 9
and the circumferential surface of the large-diameter cylindrical portion IAA. Reference numeral 14 denotes a coil spring disposed between the lower end surface 11A of the fuel vibrator 11 and the upper end surface 15A of the anchor 15. The coil spring 14 urges the anchor 15 downward, and the contact surface 6D of the needle valve 6 is pressed against the valve seat 2E.

15 is the inner peripheral surface of the reduced diameter portion IC of the main body 1 and the coil bobbin 9;
The anchor 15 is slidably attached to the inner circumferential surface of the anchor 15, and the anchor 15 is formed into a closed cylinder shape, and the needle valve 6 is mounted inside the anchor 15.
The proximal end enlarged diameter portion 6A is fitted and fixed. Further, a slight gap A is formed between the upper end surface 15A of the anchor 15 and the distal end surface 8C1 of the core portion 8C, and when the coil 10 is energized, the anchor 15 is attracted to the core portion 8c, and the anchor 15 is attracted to the core portion 8c. The anchor 15 is displaced by the gap A, and the needle valve 6 is pulled upward and opened. A groove-shaped fuel passage 16 through which fuel from the fuel vibrator 11 flows is provided on the outer peripheral surface of the anchor 15.

In the figure, 17 is a fuel hose connected to the extension part 8B of the core member 8, and the fuel hose 17 is connected to a fuel pump (not shown).
The fuel pumped from the pump is supplied into the fuel vibrator 11 via the filter 18. Reference numeral 19 denotes a male connector located at the upper part of the main body 1 and integrally formed on the outer periphery of the extending portion 8B of the core member 8. The male connector 19 is connected to the coil 10 of the electromagnetic actuator 7, and is connected to an external control device ( (not shown) side is connected to the side connector (not shown). Then, power is supplied to the coil 10 by the injection pulse whose pulse width is controlled by the control device, and the core portion 8C
The anchor 15 is attracted by generating a magnetic force on the distal end surface 8C side.

The conventional fuel injector has the above-described configuration, and fuel is supplied from the fuel pump (not shown) into the main body 1 through the fuel hose 17, filter 18, fuel vibrator 11, etc. at a predetermined fuel pressure. The fuel is supplied into the fuel passage 2C through the fuel passage 16 outside the anchor 15 and the gap between the needle valve 6 and the stopper 5. When power is supplied to the coil 1o by an injection pulse from the control device, the core member 8 is excited, and the anchor 15 is attached to the coil spring 14 on the distal end surface 8C of the core portion 8C.
The needle valve 6 is pulled up to open the needle valve 6, and the fuel is injected outward from the injection port 2D of the injection nozzle 2. When the power supply is stopped, the anchor 15 is pressed by the coil spring 14, and the needle valve 6
is seated on the valve seat 2A and stops fuel injection.

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, the injection nozzle 2
The injection port 2D has a constant diameter and shape and does not deform, so the injection state can vary from high load and high speed operation with a large fuel injection amount to low load and low speed operation with a small fuel injection amount. (injection angle and injection amount per unit time) are constant, and there is a problem that the injection state cannot be optimally controlled according to various operating states of the engine.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a fuel injector that can optimally control fuel injection conditions according to various operating conditions of an engine.

[One Means for Solving the Problems] The configuration adopted by the present invention to solve the above-mentioned problems includes an injector main body, an injection nozzle provided in the injector main body and having a fuel injection port, and the injection nozzle provided in the injector main body and having a fuel injection port. A fuel injector comprising a needle valve that is movably provided in the nozzle in the axial direction and opens and closes the injection port, and an electromagnetic actuator that is provided in the injector body to open and close the needle valve. The injection port of the injection nozzle is provided with a piezoelectric element formed in an annular shape and formed by laminating a plurality of piezoelectric elements in the axial direction so as to form the injection port.

[Effect]

With the above configuration, by selectively applying a voltage to each piezoelectric element, the inner diameter (aperture) of each piezoelectric element is changed appropriately, and the shape of the injection port is transformed into a shape according to the operating state of the engine, thereby achieving optimal injection. Shape the state.

【Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. Note that the overall configuration of the fuel injector of this embodiment is almost the same as that of the prior art described above, so the same members are given the same reference numerals and the explanation thereof will be omitted.

In the figure, 20 is the injection nozzle of this embodiment, and the injection nozzle 2
0 is roughly composed of an inner cylinder part 21, an outer cylinder part 22, and a piezoelectric element 23. Note that the reason why the injection nozzle 20 is divided into the inner cylinder part 21 and the outer cylinder part 22 is to facilitate the attachment of the piezoelectric element 23, and both may be integrally molded.

Here, the injection nozzle 20 consists of a large diameter cylinder part 21A of the inner cylinder part 21 and a flange 22A of the outer cylinder part 22, and these are directly fitted together with the stopper 5 into the small diameter cylinder part IB, and the small diameter cylinder part IB is fitted directly with the stopper 5. The large diameter base 2OA is fixedly supported on the main body 1 side by caulking the tip of part IB, and the cylindrical body part 21 of the inner cylinder part 21.
A valve cylinder part 20B formed by B and the cylinder body part 22B of the outer cylinder part 22, a fuel passage 20C provided to pass through the inside of the inner cylinder part 21 upward and downward, and the tip of the inner cylinder part 21. opening 21
Inner circumferential opening 22D of the tip reduced diameter portion 22C of the C1 outer cylinder portion 22
and a fuel injection port 20D formed by a Teflon inner cylinder 33 of a piezoelectric element 23, which will be described later, and which serves as an outlet of the fuel passage 20G;
a valve seat 20E formed at the tip of the valve seat 20E, and
An enlarged diameter stepped portion 22E into which the piezoelectric element 23 is fitted is formed in the reduced diameter portion 22C at the tip of the outer cylinder portion 22.

The piezoelectric element 23 is firmly fixed and supported between the distal end surface 21D of the inner cylinder part 21 while being fitted into the enlarged diameter step part 22E, and forms a part of the injection port 20D. Here, as shown in FIGS. 3 and 4, the piezoelectric element 23 includes two piezoelectric plates 24 and 25 formed in a donut shape, and a through hole 24A inside each piezoelectric plate 24 and 25. , 25A, plus electrodes 26 and 27 applied to the inner peripheral surface, and each piezoelectric plate 24°2
Negative electrodes 28, 29 applied to the outer circumferential surface of 5 and each piezoelectric plate 24, 25 are laminated, and on top of that, 3 each provided on both sides and between each piezoelectric plate 24, 25.
donut plate-shaped Teflon sheets 30, 31, 32, each piezoelectric plate 24, 25 and each Teflon sheet 30
, 31° 32 are laminated, each through hole 24
A, Teflon inner cylinder 33 that is provided through 25A and forms the inner circumferential surface of the injection port 20D, and each piezoelectric plate 24, 25.
The Teflon sheets 30, 31, and 32 are laminated, and a Teflon inner cylinder 33 is inserted, and a Teflon outer cylinder 34 is attached so as to wrap around the outer periphery of these sheets and protect each outer peripheral surface. Note that each piezoelectric plate 24.
Lead zirconate titanate or the like is used as the material of 25, and when a voltage is applied to each piezoelectric plate 24.25, each piezoelectric plate 24.25 changes in the radial direction to form the through holes 24A, 25A.
It is designed to reduce the diameter of the In addition, each piezoelectric plate 2
The reason Teflon is used as the material for wrapping 4.25 is that it is flexible and has excellent oil resistance.

And the positive electrode 26.27 is connected to each lead wire 35.36.
The negative electrode 2 is connected by soldering, silver brazing, etc.
8.29 is connected to the lead wire 37 by soldering, silver soldering, etc. Each lead wire 35, 36, 37 is connected to the valve cylinder part 2.
It is wired to a wiring groove 38 (see FIG. 2) formed between each cylindrical body portion 21B and 22B constituting 0B, and connected to a connector (not shown) provided on the main body l side.

Reference numeral 39 in FIG. 1 denotes a protector attached to the outer periphery of the valve barrel portion 20B to protect the valve barrel portion 20B.

The piezoelectric element 23 configured as described above is fitted into the enlarged diameter stepped portion 22H provided at the enlarged diameter end portion 22G of the outer cylindrical portion 22, and the outer cylindrical portion 22 is fitted and fixed to the inner cylindrical portion 21. By doing so,
It is provided to be securely sandwiched between the enlarged diameter step portion 22E and the distal end surface 210 of the inner cylinder portion 21. Lead wires 35, 36° 3 are connected to each piezoelectric plate 24, 25 of the piezoelectric element 23.
7 is connected to an external control device via a connector provided on the main body 1, and the control device controls each piezoelectric plate 24.2.
5 is selectively applied with a voltage according to the operating condition of the engine, and the piezoelectric plates 24 and 25 are deformed to form a Teflon inner cylinder 33.
The aperture shape of the injection port 20D formed in the above is deformed into an appropriate shape.

On the other hand, the voltage applied to each piezoelectric plate 24.25 of the piezoelectric element 23 is controlled by a control device.
．． 25, as shown in FIG. 5, a voltage is applied only to the upper piezoelectric plate 24 to
In one case, the diameter of the injection port 20D is gradually expanded toward the downstream side (a shape with a thicker tip), and in the other, as shown in FIG. In the case where the diameter of the injection port 2 is increased (tapered shape), as shown in FIG.
In the case where the diameter of the entire injection port 20D is uniformly reduced (reduced diameter shape), as shown in Fig. 2, no voltage is applied to both of the piezoelectric plates 24 and 25, and the entire injection port 20D is enlarged uniformly. There are cases where the diameter is maintained at the same diameter (enlarged diameter shape), and it is controlled in one of the modes depending on the operating conditions of the engine. In addition, in the above four embodiments, the Teflon inner cylinder 33 is flexibly deformed to form the injection port 20D.
The shape of the inner peripheral surface is smoothly deformed.

The fuel injector of this embodiment is constructed as described above, and its operation will be explained next.

Note that the overall configuration of the fuel injector is almost the same as that of the prior art fuel injector described above, and its explanation will be omitted here.

In this embodiment, the fuel passage 20 of the injection nozzle 20
The fuel that has passed through G and reached the injection port 20D is injected from the injection port 20D into the combustion chamber of the engine when the needle valve 6 is opened by displacement. The piezoelectric element 23 is controlled by the device. That is,
During low-load, low-speed operation such as in an idling state, a voltage is applied only to the upper piezoelectric plate 24 to reduce the diameter of the through hole 24A of the piezoelectric plate 24, as shown in FIG. As a result, while the through hole 24A becomes smaller, the through hole 25A in the lower piezoelectric plate 25 remains large in diameter, and the Teflon inner cylinder 33 deforms the injection port 20D into a smooth tapered shape. . As a result, the fuel injected from the injection port 20D is injected at a large injection angle, mixes well with air, and achieves stable combustion.

When a certain number of rotations is maintained and there is a moderate load, such as when running at a constant speed, voltage is applied only to the lower piezoelectric plate 25 to prevent the piezoelectric plate 25 from penetrating, as shown in FIG. hole 2
Reduce the diameter of 5A. As a result, while the through hole 25A becomes smaller, the through hole 24A in the upper piezoelectric plate 24 remains large in diameter, and the Teflon inner cylinder 33 deforms the injection port 20D into a smoothly tapered shape. On the other hand, in a constant speed running state, although a large amount of fuel is not required, a certain amount of fuel must be constantly supplied, and the flow rate of intake air is high, so fuel is injected from the tapered injection port 20D. is narrowed down to a small spray angle and the most efficient spray is effectively sprayed to the point.

At high loads and high rotations, as shown in Figure 2, each piezoelectric plate 24
．． No voltage is applied to 25, and the through holes 24A, 25A of each piezoelectric plate 24, 25 are maintained in an enlarged diameter shape. As a result, a large amount of fuel can be injected from the injection port 20D, and sufficient fuel commensurate with the output of the engine can be supplied.

Also, like in economical driving conditions, the output is minimized,
When maintaining a constant speed, as shown in FIG. 7, voltage is applied to both of the piezoelectric plates 24 and 25,
Make 4A and 25A into a reduced diameter shape. As a result, the amount of fuel injected is reduced while maintaining the minimum output.
Fuel efficiency improves.

As described above, by controlling the voltage applied to each piezoelectric plate 24, 25 by the control device, the injection port 20D can be deformed into an appropriate shape according to the operating conditions of the engine. This makes it possible to create optimal fuel injection conditions, improving engine performance, fuel efficiency, etc.

In this embodiment, two piezoelectric plates 24 and 25 of the piezoelectric element 23 forming the injection nozzle 20D of the injection nozzle 20 are laminated, but the present invention is not limited to this. It may also be constructed by laminating plates. In this case, the injection port 2 of the injection nozzle 20 is
The 0D can be molded into a smoother shape, and a more efficient fuel injection state can be formed.

On the other hand, a Teflon sheet 30 covering each piezoelectric plate 24, 25,
31, 32, Teflon inner cylinder 33 and Teflon outer cylinder 34
may be constructed as separate members, and
The Teflon sheet 30.degree. 31.32 and the Teflon inner tube 33 may be integrally molded, and the Teflon outer tube 34 may be attached with each piezoelectric plate 24, 25 attached. Furthermore, Teflon sheets 30, 31, 32, Teflon inner cylinder 33
and a Teflon outer cylinder 34, and each piezoelectric plate 24, 25 inside.
It may be integrally molded with the material covered.

〔Effect of the invention〕

As detailed above, according to the present invention, a piezoelectric element formed by laminating a plurality of piezoelectric elements in an annular shape so as to form the injection port is provided at the injection port of the injection nozzle, and each piezoelectric element is formed by laminating a plurality of piezoelectric elements in the axial direction. By selectively applying a voltage to the element, the diameter of the injection port can be changed to an appropriate shape, so the injection port can be changed to an appropriate shape depending on the operating condition of the engine, and the optimum fuel can be obtained. The injection state can be shaped.

[Brief explanation of drawings]

1 to 7 relate to embodiments of the present invention, in which FIG. 1 is a partial sectional view showing the injection nozzle portion of the fuel injector, and FIG. Figure 3 is an exploded perspective view showing the Teflon sheet, Teflon inner cylinder and Teflon outer cylinder attached to cover each piezoelectric plate, Figure 4 is a perspective view showing two piezoelectric plates, and Figure 5 is A cross-sectional view of the main part showing a state where voltage is applied only to the upper piezoelectric plate and the injection nozzle is made into a tapered shape. Figure 6 shows a state where voltage is applied only to the lower piezoelectric plate and the injection nozzle is made into a tapered shape. Figure 7 is a cross-sectional view of the main part showing the state in which voltage is applied to the piezoelectric plates on both sides of the upper and lower sides to reduce the diameter of the injection port, and Figure 8 is a fuel tank according to the prior art. FIG. 3 is a longitudinal cross-sectional view of the injector. 1... Injector body, 6... Needle valve, 7...
...Electromagnetic actuator, 20...Injection nozzle, 20
D...Injection port, 23...Piezoelectric element, 24.25...
・Piezoelectric plate.

Claims (1)

[Claims] an injector body; provided on the injector body;
an injection nozzle having a fuel injection port; a needle valve movable in the injection nozzle in the axial direction to open and close the injection port; and a needle valve provided in the injector body to open and close the needle valve. In the fuel injector, a piezoelectric element formed by stacking a plurality of piezoelectric elements in an axial direction is provided at the injection port of the injection nozzle in an annular shape so as to form the injection port, and A fuel injector characterized in that the aperture of the injection port can be changed into an appropriate shape by selectively applying a voltage to each piezoelectric element.