JPS5844263A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To reduce time-lag in closing of a fuel injection valve by adding a driving signal to a coil part united in one body with a needle and driving the needle which electromagnetically operates fuel injection. CONSTITUTION:A coil part 16, wound round by a wire 8, is united in one body with a needle 3, which is directly moved by an action of the coil part. Since magnets of a permanent magnet 14 are led to concentrate in a cylindrical space formed between a ball piece 10 and a plate 15 and then the coil 16 is inserted in the gap, driving force is generated on the coil part 16 when a driving pulse is impressed on the wire 8 wound around said coil 16. Accordingly, a total of repulsive force of a spring 6 and driving force generated by electric current flowing through the wire 8 works on the coil part 16, and this injection valve may be closed with less time-lag as compared with a valve in the past which is closed only by repulsive force of a spring.

Description

[Detailed description of the invention] It fights against the injection valve.

A schematic sectional view of the mechanism of a conventional solenoid valve is shown in No. zll.

When a sea pulse is applied to the solenoid coil, the core l
is sucked upward, and since the needle 3 is integrated with the core 1, the needle 3 moves 97) until the 7-lunge 4 hits the spacer device. When the driving pulse disappears, the needle 3 is returned to its original position by the repulsive force of the spring 60. Need#
Since the amount of glue 7F is constant, the injection amount is determined by the time the needle is in the upward position 97), that is, the time the solenoid coil 2 is energized.

In such a configuration, if the force of the return spring is weakened in order to move the core faster, it will take longer to return, and if the force of the return spring is strengthened to speed up the return time, the startup time will be reduced. It will be long. Therefore, when used as a fuel injection valve, there are problems as described in detail below, such as when the injection time is short or at high rotation speeds where the injection interval approaches each other.

Figure 2 shows the relationship between drive pulse, needle lift, and injection amount. The fuel ejected in - strokes is given by the following equation.

Spout amount q = qo + qm + q.

= Q o % T o + Q (ti-To) -
)QcTaQ O<< Q≠Q.

,”, +lF&Q (t i −(T o−T c)
) Also, the minimum injection time twin =To-1-T! l
o, so the minimum injection amount qmin=Q(twin −(To−To
)):Q(T(1+T110)).

Therefore, the minimum injection amount qmim is a function of T o +T B o.

here · tl: energization time, tra-.t: rest time.

! o: Valve opening delay time, To: Valve closing delay time, tx6:
When the valve opens, it's time for two dollars, 'I'! IC: Dynamic injection amount when valve opening is delayed.

qc: Dynamic injection amount at valve closing delay eq” Dynamic injection amount at valve opening *
Qo: Static injection amount when valve opening is delayed *Qc” Static injection amount when valve closing is delayed, q: Static injection amount when valve opening is delayed.

That is, in order to make the minimum injection amount smaller, the valve closing delay time T
Either shorten c or shorten the needle bounce time TIC when opening the valve. However, in the conventional injection valve, the needle 3 is returned using the repulsive force of the spring 6, so it is not possible to shorten the valve closing delay time. Further, since the stoichiometry is defined by the collision of the 7th rank with the spacer 5 when the valve is opened, it is also impossible to control the pounding that occurs at that time.

That is, the minimum injection amount is uniquely determined by mechanical characteristics, and it is difficult to control the minimum injection amount externally or to determine the minimum injection amount more efficiently.

The present invention is an injection valve that causes the needle 3 to behave by applying a drive signal to a coil portion 16 integrated with the needle 3 of the injection valve, and the current flowing through the wire 8 of the coil portion 16 has directionality. That is, if a current is made to flow in the opposite direction to the direction of the current that is passed to pull the needle 3 upward, a driving force is generated that pulls the needle 3 downward, resulting in a valve closing delay time! O can be shortened. □ Also, by adopting a structure in which the permanent magnet is attached around the coil portion 16, the wire 8 is placed in a high magnetic field. As a result, the damping time of the pound at valve opening is significantly shortened, and in combination with the reduction in the valve closing delay time To, the minimum injection amount can be further reduced.

Another object of the present invention is that by configuring the drive circuit 17 to protrude into the fuel path, the fuel flow cools the drive circuit and a large drive current can be obtained.

This reduces the load on the computer for driving this injection valve, leading to cost reductions for the entire system.

Embodiments of the present invention will be described in detail below with reference to the drawings. A schematic cross-sectional view of the structure of the injection valve □ according to the present invention is shown in 3rd wJ. The coil part 16 has a wire 8 wound thereon, and the wire is connected to the drive circuit lf via the stay 13 made of an insulator, and the drive circuit 'lf is connected to the connector 9. ing. Further, the coil section 16 is integrated with the needle 3, and the coil section 16 has a structure that directly moves the needle. A driving circuit 17 extending from the fuel injection groove 1 through the fuel injection port 12 to the injection lobe protrudes. That is, the outflowing fuel is injected while cooling the drive circuit 17.
It has a structure that reaches the mouth 5. The magnetism of the permanent magnet 14 is guided to the □ so that it is concentrated in the cylindrical space created between the pole piece 10 and the plate 15, and the coil part 16 is inserted into the space. Wall part 16
The drive pulse becomes a mark on the 8 wound around.

When the injection signal τl is input to the input terminal M of the drive control circuit, the drive control circuit generates a drive pulse to turn the transistors Ql and Q4 to 01 for a time corresponding to the injection signal v'l. As a result, current flow l flows, and coil part 1
6 is sucked upward.

Since the needle 3 is integrated with the coil portion 16, the needle 3 is lifted until the seven flange 4 hits the spacer 5.

When the valve is closed, are transistors Q, X, and Q4 turned off? let me,
Eliminate drive current and labor. At that time, a back electromotive force is generated that tries to prevent this, and a current flows in the same direction as the coil L, but since the transistors Q2 and Q3 are not turned on yet, the current is consumed in the coil L. τ2 is the time required for this.

After that, transistor Q! , when Q3 is turned ON, a current xm opposite to that when the valve is opened flows. τ3 is the time required to obtain a fast valve closing time.

Therefore, the combined force of the repulsive force of the spring 6 and the driving force generated by the current flowing through the wire 8 acts on the coil portion 16, and the injection valve closes with a shorter delay time than the conventional injection valve that closes only with the repulsive force of the spring. Close the valve. In other words, the injection valve has a smaller minimum injection amount than conventional injection valves. Since the lift amount of needle 3 is constant, the injection amount is
It is regulated by the time during which the needle is lifted upward, that is, the time during which the wire 8 is energized to open the valve.

An equivalent circuit of the injection valve drive circuit is shown in (&) in FIG.

Now, when a driving pulse is applied to the wire 8 in the direction of opening the valve, the equivalent circuit will be as shown in Figure S. In this case, rO
Since is the internal impedance of the power supply and is so small that it can be ignored, it can be considered that (k) in Fig. 6 is (0). .

In other words, one closed loop circuit is formed. This circuit consists of the player 15 and the pole piece 10 shown in
Because it is located in the air gap, it exists in a magnetic field.

If the coil section (0) of the younger brother aWJ is shifted in the direction of the arrow P, an electromotive force of =-raccoon t is generated in the circuit according to Lenz's law. The electric charge generated by this electromotive force generates a low curve of f=.(*×8). The direction is the direction of arrow q in (0) of FIG. That is, a force acts on coil B that attempts to prevent coil L from moving. This means that a force is generated that tries to prevent the needle 3 from bouncing, and the injection valve of the present invention has a shorter needle pounding time 'rma when the valve is opened compared to conventional products. That is, the minimum injection amount also becomes smaller.

FIG. 6 shows a schematic structure of a high magnetic flux density type injection valve according to the s2 embodiment of the present invention. This injection valve is designed to obtain a high magnetic flux by making the plate 1s and the pole piece 10 melted as shown in FIG. 6, thereby making it possible to further improve the response speed.

As mentioned above, (1) When a current is passed through the coil part integrated with the needle of the injection valve, the direction of the force received by the needle changes depending on the direction of the current flow. There is an effect that the valve closing delay time can be shortened by flowing a current opposite to the current.

The minimum injection amount becomes smaller as the valve closing time increases, so by using the above drive method for the injector of the present invention, a smaller minimum injection amount can be obtained and more fine-grained engine control can be achieved. It becomes possible.

(2) By placing the wire of the coil part that is integrated with the injection valve needle in a magnetic field and applying a drive signal to it, a force that prevents bouncing is applied and the needle bouncing time when the valve is opened can be shortened. The injection valve with this structure has the advantage of being able to obtain a smaller minimum injection amount compared to conventional products because the needle pound time when opening the valve is shorter (the shorter the needle pound time is, the smaller it becomes). have an effect.

(5) By adopting a structure in which the drive circuit for moving the injection valve is exposed to the fuel path, the fuel flow cools the drive circuit, making it possible to increase the drive current.

As a result, although conventionally a complicated control circuit was required on the computer side, a simpler circuit is required, and the cost of the entire system can be reduced.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional product, Figure 2 is a diagram of the relationship between the drive pulse and the solenoid valve, Figure 3 is a sectional view of the embodiment of the present invention, Figure 4 is a diagram of the relationship between the drive circuit and control signals, and Figure 4 is a diagram of the relationship between the drive circuit and control signals. FIG. 5 is an equivalent circuit diagram of the driving section, and FIG. 6 is a sectional view of an embodiment of the cylinder 2 of the present invention. 1...Core, 2...Solenoid coil, 3...Needle. 4...7 lunge, 5...spacer, 6-...spring. 7... Injection port, 8... Wire, 9-... Funecta,
10--Pole piece, 11--Fuel injection groove, 1g
-...Fuel injection port, 13...Stay, 14-...Permanent magnet, 15...Placey, 16...Coil part, 17
...Drive circuit. Representative Patent Attorney Okabe I Figure 2 Figure 4 Figure 5 Cλ) (b) (C) ↑ Nail Figure 6

Claims (2)

[Claims] (1) In a solenoid valve that controls a nozzle needle using an electromagnet, the needle, a magnetic body connected to the needle and expanding into a 7-flange shape, and a coil that is in contact with the upper part of the 7-flange shape of the magnetic body. A permanent magnet arranged so as to coaxially envelop the coil section, a hollow cylindrical plate similar to that in contact with the permanent magnet, a spring arranged coaxially on the white flaw of the coil section, and a seven flange. It has a spacer for receiving the permanent magnet, and a drive circuit and path for driving the coil section in a cutout part of the permanent magnet, and a drive current is passed through the coil section to control the needle and fuel injection is performed electromagnetically. A fuel injection valve characterized by being operated to. (2) The fuel injection valve according to claim 1, characterized in that a drive circuit for driving the coil portion is arranged on a supply path of fuel to be injected.