JPH03225067A - Variable static flow type fuel injection device - Google Patents

Abstract

PURPOSE:To obtain a composite characteristic provided with a small and a large flow characteristics by providing a fuel passage with plural mutually parallel passage parts, as well as forming individual measuring parts for these passage parts, and opening/closing at least one of these passage parts. CONSTITUTION:A fuel passage 18 is provided with plural mutually parallel passage parts 42, 44, including plural measuring parts 50, 56 formed individually to these passage parts 42, 44. A switching means 62 is further provided to switch at least one of plural passage parts 42, 44. The whole passage sectional area change of the fuel measuring part depends on whether this switching means 62 is in the closed or open state. That is, in the closed state, a static flow characteristic of relatively small flow compared to the open state is obtained, while in the open state, a static characteristic of relatively large flow compared to the closed state is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a fuel injection device that is installed in a fuel supply system of an engine and injects fuel, and particularly relates to an improvement in the structure for setting the amount of fuel injection per injection. .

<Prior art> A type of well-known fuel injection device (so-called injector) has a body, a fuel passage passing through the body, an injection port formed at the tip of the fuel passage, and an injection port that opens and closes. A type of valve is known that includes a shaft-shaped valve member and a valve drive means that opens and closes the valve member in the axial direction. For example, Japanese Utility Model Application Publication No. 58-132162 discloses this type of injector.

In such an injector, it is necessary to set the amount of fuel injected per injection 9A as accurately as possible, but for this purpose, a fuel metering section, which is a type of throttle, is installed in the fuel passage in the vicinity of the upstream side of the injection port. It is provided. Usually, a passage cross-sectional area corresponding to the difference between the cross-sectional area of the fuel passage and the cross-sectional area of the valve member is given, and based on the product of this passage cross-sectional area and the injection time (inter-valve time), σ injection is performed per time. Amount is specified.

In response to the intake stroke of the engine, the valve member opens at a constant rate to perform injection, and the injection time is generally duty-controlled by a pulse signal. Here, when the engine output is low, the suction air suspension is small, so the injection time per injection (,) 1 rus width) is short, and when the engine output is high, the 4J intake air V is large, so the pulse width is become longer.

Problems to be Solved by the Invention Incidentally, conventionally, in such an injector, the passage cross-sectional area of the fuel metering section was uniquely determined at the design and manufacturing stage, and the passage cross-sectional area was fixed. The flow characteristics of the injector are also uniquely determined by this.

FIG. 5 shows the characteristic (2) of a small flow rate injector in which the passage cross-sectional area of the fuel metering section is set small, and the characteristic (2) of a large flow rate injector in which the passage cross-sectional area of the fuel metering section is set large. In both characteristics, as the pulse width (injection time) increases, the injection flow rate increases from zero to Ql and Q2 at full opening, respectively, but in reality, it is difficult to determine the usable range of this pulse width for practical use. The range is limited to the range W in which the pulse width and the injection flow rate have a linear relationship due to the problem of flow rate variations. Therefore, in practice, in characteristic 1 of small flow rate, the minimum flow @c
In the region Qs from Nmin to the maximum flow qlmax, and in the large flow characteristic ■, the region 1i! from the minimum flow q2Illin to the maximum flow fJq2max! The QL determines the flow capacity of each type, and each has its advantages and disadvantages.

In other words, with the small flow rate characteristic ■, fuel consumption can be kept low in the engine's lowest output state (such as when the vehicle engine is idling), but when high output is required (such as when the vehicle is accelerating), the injection flow rate is The disadvantage is that the output has reached a plateau and the output limit is low. On the other hand, with the large flow rate characteristic (3), a sufficient high output can be obtained, but it is difficult to suppress the injection flow rate to the necessary minimum in the lowest output state, resulting in more fuel being consumed than necessary.

An object of the present invention is to provide a single injector (fuel injection unit) with both small flow rate characteristics and large flow rate characteristics, and to take advantage of the advantages of each.

Means for Solving the Problems> The fuel injection device according to the present invention is premised on including the body, fuel passage, injection port, valve member, valve driving means, and fuel gauge ω portion as described above, and the following: It is composed of the following requirements.

That is, (1) the fuel passage has a plurality of passage sections parallel to each other; (2) the fuel metering section includes a plurality of metering sections formed individually for the plurality of passage sections; Opening/closing means are provided for opening and closing at least one passageway section of the section.

Here, for example, there is a mode in which a first passage section having a first measuring section and a second passage section having a second measuring section are provided in parallel with each other, and an opening/closing means is provided in, for example, the second passage.

Alternatively, a first passage section having a medium flow metering section and a second passage section having a small flow rate metering section are provided in parallel with each other, and each passage section is provided with an opening/closing means, so that only the first passage is selectively provided. It is also possible to obtain characteristics of small flow rate, medium flow rate, and large flow rate by opening only the second passage or opening both passages.

Function> In the fuel injection device according to the present invention, the cross-sectional area of the passage as a whole of the fuel gauge opening changes depending on whether the opening/closing means is in the closed state or the open state.

That is, in the closed state, a static flow characteristic with a relatively small flow rate is obtained compared to the open state, and conversely, in the open state, a static flow characteristic with a relatively large flow rate is obtained compared to the open state. .

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

The fuel injection device (injector) 2 shown in FIG. 1 includes a body 10 in which body components 3, 4, 6 and 8 are assembled in a liquid-tight manner. A fuel passage 18 is formed in the body 10 from the fuel port 12 at the base end through the filter 14 to the injection port 16 at the tip end. The injection port 16 is a tapered hole-shaped portion with a conical surface whose inner diameter increases toward the tip, and there is an elongated ring-shaped valve portion 022 with a valve head 20 at the tip that opens and closes the injection port 16.
is provided so as to be movable in the axial direction within the body 10. The valve head 20 is a truncated cone-shaped portion that approximately corresponds to the injection port 16, but its outer peripheral surface has a slightly gentler 7-pa angle than the inner peripheral surface of the injection port 16, and extends from the outside of the body 10 to the inside. In a state where the valve head 20 is seated on the injection port 16, the peripheral edge of the distal end of the valve head 20 comes into close contact with the peripheral edge of the opening of the injection port 16, thereby forming a seal portion.

The valve member 22 is biased by the main spring 24 in the direction of closing the injection port 16 (to the right in FIG. 1), while receiving a spring force in the opposite direction (in the opening direction) by the weaker cushion spring 26. But in the end,
Based on the difference in spring force between them, it is always biased in the closing direction. The cushion spring 26 is connected to the valve head 2
0 serves to soften the impact when sitting on the injection port 16.

A first solenoid 28 for driving a valve that pushes the valve member 22 in the opening direction against the main spring 24 is provided in the body 10 .

A coil 34 is wound around the core 30 of the first solenoid 28 via a bobbin 32, and an excitation current is supplied to the coil 34 through terminals 36 and 38. Valve member 22 extends through core 30 and has armature 40 at its end.
is fixed. The air gap between the armature 40 and the core 30 defines the movement stroke of the valve member 22. Note that the fuel passage 18 is connected to the armature 40.
and extends between the core 30 and the valve member 22 .

The fuel passage 18 branches into a first passage part 42 and a second passage part 44 on the downstream side, and joins again at the injection port 16. The -th passage section 42 is formed concentrically with the injection port 16, extends through the center of the body component 6 along the axial direction of the valve member 22, and is connected to the injection port 16.
A distal end portion of the valve member 22 is inserted through the passage portion 42 so as to be movable in the axial direction. Guide portions 46.48 having a larger diameter than the other portions are formed at the distal end portion of the valve member 22 at a predetermined distance in the axial direction. Movement of the valve member 22 is guided by the surface. In this way, the first passage portion 42 serves as both the guide hole of the valve member 22 and the fuel passage, but the outer peripheral surface of the guide portions 46 and 48 of the valve member 22 is a cylindrical outer peripheral surface as shown in FIG. The cross-sectional shape obtained by cutting off at four planes A1 to A4 along the axial direction is 6, and the above-mentioned first passage section 42 is formed by gaps at four locations.
is ensured.

A first measuring section 50 is provided very close to the first flow side of the injection port 16 in the second passage section 42 shown in FIG.

As shown in an enlarged view in FIG. 3, this first measuring section 50 has an annular passageway cross-sectional area S1 corresponding to the difference in cross-sectional area between the first passageway section 42 and the valve member 22 at a predetermined point in the flow direction. A constricted portion extending over a short length of the valve member 22
It is formed between the cylindrical outer circumferential surface 52 of and the cylindrical inner circumferential surface 54 of the second passage section 42 .

On the other hand, the aforementioned second passage section 44 is formed with an annular cross section between the body constituent members 6 and 8 on the outside of the first passage section 42 and extends in the axial direction. is closed and communicates with the injection port 16 through a small hole 56 formed in this closed portion. As is clear from Figure 3,
This small hole 56 constitutes a second measuring part of the second passage part 44 with respect to the first measuring part 50 of the first passage part 42, and the diameter of this hole gives a passage cross section S2. . Hereinafter, this small hole will be referred to as a second measuring section 56.

This second metering section 56 is in a parallel positional relationship with the first metering section 50, and the sum S1+82 of these passage cross-sectional areas becomes the fuel metering section passage cross-sectional area as a whole.

FIG. 2 shows the upstream ends of the first passage section 42 and the second passage section 44 in FIG. 1. Both passage portions 42 and 44 are connected to each opening 5.
8 and 60 communicate with the fuel passage 18 on the upstream side, and a movable plate 62 made of a magnetic material is provided at these portions so as to be movable in the axial direction of the valve member 22.

The openings 58 and 60 of both passage sections 42 and 44 are
The seat surface 64 is formed on a common seat surface 64 within the valve member 22, and this seat surface 64 is formed as a plane spanning the body constituent members 6 and 8 at an angle C with the axial direction of the valve member 22. The movable plate 62 has a center hole 65 in its center that corresponds to the opening 58 of the first passage section 42, and while being held in a position parallel to the seat surface 64, the movement is guided by the inner circumferential surface of the body component 8. It is now possible to do so.

This movable plate 62 is normally urged by a spring 66 to a closed position where it is seated on the seat surface 64, and in this state, fuel flows only to the first passage section 42, and fuel flows to the second passage section 44. is blocked. Furthermore, the movable plate 62 is movable to an open position where it hits a stopper surface 68 on the opposite side to the seat surface 64, and this stopper surface 68
8 is an annular member 70 fixed inside the body component 8
It consists of the downstream end face of

A second solenoid 72 is built into the body 10 as a means for moving the movable plate 62. As shown in FIG. 1, the core 74 of the second solenoid 72 has a cylindrical shape with seven flanges and is fixed in the body 10, and has two coils 78 wound around the opening via a bobbin 76. Excitation current is supplied by a terminal 80 (only one shown in the figure).

The valve member 22 extends loosely through the opening 74, with the fuel passage 18 passing therebetween.

In this embodiment, the movable plate 62. The spring 66 and the second solenoid 72 constitute means for opening and closing the second passage portion 44 .

Next, the operation will be explained.

As shown in FIG. 2(a), when the second solenoid 72 is de-energized and the movable plate 62 is seated on the seat surface 64 by the spring 66 and is in the closed position, the fuel flows to the second passage portion 44. is blocked, while the -th passage section 42
The flow of fuel to is allowed through the central hole 65 of the movable plate 64. In this state, when the first solenoid 28 in FIG. 1 is excited for a time corresponding to the pulse width based on the duty control, the valve member 22
is moved in the opening direction against the As a result, injection port 1
6 is opened, fuel is injected only through the second passage section 42 at J5 in FIG. 3, and the injection flow ω at this time is
is defined by the second measuring section 50 (passage cross-sectional area Sl). Let us now assume that the static flow rate characteristic at this time corresponds to characteristic (2) in FIG.

On the other hand, from this state, as shown in FIG. 2(b), when the second solenoid 72 is energized and the movable plate 62 is moved to the open position where it hits the stopper surface 68, the fuel flows into the second passage section 42. and the second passage portion 44. When the valve member 22 is opened by the first solenoid 28 in this state, as shown in FIG.
The injection port 1 passes through both the passage section 42 and the second passage section 44.
Fuel is injected from 6. The injection flow rate at this time is the passage cross-sectional area S1 of the first measuring part 50 and the passage cross-sectional area S1 of the second measuring part
2 (81+82), and maintains a relatively large flow rate characteristic.

Now, if the static flow rate characteristic in this state corresponds to the characteristic (■) in Fig. 5, the flow rate characteristic changes from the characteristic to the characteristic (2) because the movable plate 62 has been switched from the closed position to the open position. Change.

If the switching (movement) is performed at point b of characteristic ■ and the injection time is adjusted at the same time, the flow rate characteristic will shift from point b of characteristic ■ to point 0 of characteristic ■ at that point, and from then on, the flow rate characteristic will change from point b of characteristic ■ to point 0 of characteristic ■. ■
Follow. Therefore, before and after switching the position of the movable plate, the overall flow rate characteristic becomes a composite one that extends from a-+b of characteristic (2) to c-+d of characteristic (2), and the practical injectable flow rate range is from qllo to q2ffiaX. will be expanded to. Therefore, when supplying fuel to a vehicle's engine, the injection during idling! The iFl action can be kept to the necessary minimum, and the injection amount during acceleration etc. can be made sufficiently large.

Although one embodiment of the present invention has been described above, this is literally an example, and it goes without saying that the present invention can be implemented in various modifications based on the knowledge of those skilled in the art.

<Effects of the Invention> According to the present invention, the overall passage cross-sectional area of the fuel metering section is
It is possible to increase or decrease the flow rate by selectively closing and opening the passage by the opening/closing means, and as a result, although it is a single fuel injection device, it is possible to obtain composite characteristics that combine small flow characteristics and large flow suspension characteristics. , the practical injectable flow rate from the minimum flow rate ♀ to the maximum flow rate has expanded dramatically compared to the conventional method, and the minimum flow rate can be set smaller and the maximum flow rate can be set larger. Therefore, for a vehicle engine, for example, when idling, select the small flow rate characteristic to minimize fuel consumption during idling, and when accelerating or other conditions that require output, select the large flow rate characteristic to ensure sufficient fuel consumption. It is possible to secure a high injection flow rate and obtain higher output.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a fuel injection device that is an embodiment of the present invention, and FIG. (b) shows the closed position of the plate, and (b) shows the open position. Fig. 3 is a sectional view of the fuel metering section, Fig. 4 is an rV-IV sectional view in Fig. 3, and Fig. 5 is an explanation of the prior art and the book. It is a graph used to explain the operation of the invention. 2...Fuel injection device 10...Body 16...Injection port 18...Fuel passage 20...Valve head 22...Valve member 28... First solenoid 42...Second passage section 44...Second passage section 50...Second measuring section 56...Second measuring section 62...Movable plate 64...Seat surface 72...・Second solenoid (valve drive means)

Claims (1)

[Scope of Claims] A body, a fuel passage passing through the body, an injection port formed at the tip of the fuel passage, a shaft-shaped valve member that opens and closes the injection port, and a valve member that opens and closes in the axial direction. A fuel injection device comprising: a valve driving means; and a fuel metering section, which is provided in the fuel passage close to the upstream side of the injection port and provides a narrowed passage cross-sectional area to define the injection flow rate per injection. , the fuel passage has a plurality of passage sections parallel to each other, the fuel metering section includes a plurality of metering sections formed individually for the plurality of passage sections, and at least one of the plurality of passage sections A fuel injection device with variable static flow rate, characterized in that it is provided with an opening/closing means for opening and closing a passage portion.