JPH04136449A - Fuel injector - Google Patents

Abstract

PURPOSE:To improve the responsiveness of the armature of a solenoid mechanism by allowing the electric current pattern which flows in a common solenoid mechanism for driving a fuel metering means and a fuel injection means to transfer directly from the fuel metering process to the fuel injection process. CONSTITUTION:When a solenoid mechanism 5 for operating a metering valve and a fuel injection valve is controlled by a control circuit 3, a switching circuit 4 is operated when the output signal 100 of a fuel metering signal input circuit 1 is received, and the solenoid mechanism 5 is put into electric conduction. The electric current is detected always by an electric current detection part 6d, and when a metered electric current detection part 6c judges that the electric current value reaches I1, the electric current I1 is allowed to flow in the solenoid mechanism 5 during the instructed time T1 according to the output signal 100, and fuel metering is carried out. Further, the control circuit 3 receives the output signal 101 of a fuel injection signal circuit 2, and when a rush electric current detection part 6b judges that the electric current value which flows in the solenoid mechanism 5 reaches I2, the electric current value is immediately lowered to I3, and fuel injection is carried out for the instructed time T2 by the output signal 101.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection device, and particularly to a fuel injection device applied to a two-stroke engine.

(Conventional technology) Until now, various manufacturers have been developing 2-stroke engines in response to the need for smaller, higher-output, lower fuel consumption, and lower vibration engines, but fuel injection devices suitable for 2-stroke engines have yet to be developed. It cannot be said that the requirements are fully satisfied, and the current situation is that conventional fuel injection devices for four-stroke engines are modified and used for two-stroke engines.

2. Description of the Related Art Conventionally, a fuel supply device or method for supplying fuel to an internal combustion engine is disclosed in Japanese Patent Application Laid-Open No. 62-93481.

The fuel supply device disclosed in the publication includes a method in which fuel is introduced into the air while being metered to form a mixture of fuel and air, and a fuel gas mixture is supplied to the engine at fixed time intervals relative to the engine cycle. It is disclosed that

Fig. 5 shows a fuel supply system for an internal combustion engine proposed in Japanese Patent Application Laid-Open No. 62-93481.
Fuel is supplied from 35 to the injector 130 via a pump 136.

A measured amount of fuel is injected into the chamber 132 from an injector 130.

In this fuel supply device, when the solenoid 131 operates to open the valve 133, fuel is injected from the injection hole 134 together with high pressure air.

(Problem to be Solved by the Invention) However, in the fuel injection device shown in FIG.
This method consists of two steps: one injects fuel into the high-pressure air chamber +32 by activating the solenoid in the fuel metering section 0, and the other injecting fuel into the high-pressure air chamber +32, and activating another solenoid 131. is 2
Since they are arranged individually, there are disadvantages in that not only the main body becomes large but also the control method becomes complicated.

Furthermore, since conventional devices cannot accurately detect the current corresponding to fuel metering or injection, even if an abnormality occurs in the fuel metering or fuel injection mechanism, it is difficult to quickly determine which part is abnormal. I couldn't.

(Means and effects for solving the problem) The present invention has been made in view of the above-mentioned disadvantages, and is a fuel injection device particularly suitable for a two-stroke engine, in which a metering signal and a fuel injection signal are input. a control circuit, a mixing passage to which high-pressure air is constantly supplied, a fuel metering means that is operated by a metering current outputted by the control circuit based on the metering signal and supplies a metered amount of fuel to the mixing passage; and the fuel. a fuel injection means that is actuated by a fuel injection current output by the control circuit based on an injection signal and injects the fuel supplied to the mixing passage together with the high pressure air, and the metering current and the fuel injection current are continuous. The value of the fuel injection current is larger than the value of the metering current, and the fuel metering means and the fuel injection means are driven by the same solenoid mechanism.

Therefore, since the current pattern is transferred directly from the metering process to the injection process, the response of the armature is improved.
This leads to an improvement in the responsiveness of the check valve, and allows the metering timing and fuel injection timing to be accurately defined using a simple control method.

(Example) Next, an example of the present invention will be described based on FIGS. 1 and 2.

In FIG. 1, 1 is a measurement signal input circuit for inputting a measurement signal, 2 is a fuel injection signal input circuit for inputting a fuel injection signal, and 3 is a control circuit, which connects the measurement signal input circuit 1 and the fuel injection signal input circuit 2. A control signal is input to the switching circuit 4 based on the output signals 100 and 101.

5 is a solenoid mechanism, and the operation of this valve operates the metering valve and the fuel injection valve.

Reference numeral 6 denotes a current detecting section, which is composed of a holding current detecting section 6a, an inrush current detecting section 6b, a metering current detecting section 6c, and a current detecting section 6d, and detects the current flowing to the solenoid mechanism 5, etc.

7 is a DC-DC converter that boosts the power supply (battery) voltage to a predetermined voltage.

Further, FIG. 2 shows the fuel metering current and fuel injection current flowing through the solenoid mechanism 5, and in the fuel injection current whose current value is larger than the fuel metering current, the metering current is continuous with the fuel metering current.

In FIG. 2, A1. A2 is the fuel metering current, A3~A
5 indicates the fuel injection current; at time T1 of the fuel metering current, the current value becomes II, the fuel injection current reaches the current value I2 and becomes the peak current, and the fuel injection current reaches the current value I3 at 12 hours. .

Note that T4 is the time for the fuel metering current to rise to the current value II, and T5 is the time for the fuel injection current to fall from step 3.

FIG. 3 is a diagram showing an example of a specific circuit configuration of FIG. 1, which corresponds to the block diagram of FIG. 1, and the same configurations are indicated by the same reference numerals, and detailed explanation will be omitted here.

The method of controlling the solenoid mechanism 5 will be described in detail below.

The output signal 100 of the fuel metering signal input circuit is the control circuit 3.
, the control circuit 3 operates the switching circuit 4 to connect the DC-DC converter 7 to the solenoid mechanism 5. Switching circuit 4. Current begins to flow rapidly to earth E (A1 shown in Figure 2).

This current is constantly detected by the current detection section 6d,
The output signal of the current detection section 6d is input to the metering current detection section 6c.

Here, when the metering current detection unit 6c determines that the current value flowing through the solenoid mechanism 5 reaches It in FIG. The current value II continues to flow (A2 shown in FIG. 2).

This time TI can be any arbitrary time, and the longer it is, the more fuel is metered, that is, the amount of fuel is injected.

With this, the fuel metering process is completed, and the fuel injection process continues.

The control circuit 3 includes an output signal 1 of the fuel metering signal input circuit 1.
00 and the output signal 10 of the fuel injection signal input circuit 2 continuously.
1 is input.

As a result, a current larger than the current value II begins to flow through the solenoid mechanism 5 (A3 shown in FIG. 2).

At this time, the output signal of the current detection section 6d is input to the rush current detection section 6b.

Here, when the inrush current detection unit 6b determines that the current value flowing through the solenoid mechanism 5 has reached I2, it immediately reduces the current value flowing through the solenoid mechanism 5 to I3 (A4 shown in FIG. 2).

Thereafter, the output signal of the current detection section 6d is input to the holding current detection section 6a.

Then, the current value 2 continues to flow through the solenoid mechanism 5 for the time T2 instructed by the output signal 101 of the fuel injection signal input circuit 2 (A5 shown in FIG. 2).

Note that this I2 can take any time.

With this, the fuel injection process is completed, and the control circuit 3 stops the switching circuit 4, so the value of the current flowing through the solenoid mechanism 5 becomes O.

Therefore, in this embodiment, since the current pattern flowing through the solenoid mechanism 5 is transferred directly from the fuel metering process to the fuel injection process, the responsiveness of the armature 48 in FIG. 4 of the solenoid mechanism 5 is improved.

Furthermore, since the current corresponding to fuel metering and injection is always accurately detected, the fuel metering or fuel injection mechanism can be operated quickly and reliably.

Next, the mechanical configuration of an embodiment of the fuel injection device of the present invention will be described based on FIG. 4.

41 is a magnetic metering valve, and 42 is a movable valve seat disposed coaxially with the metering valve 41 so as to be able to move toward and away from it.

A rod 64 is fixed to the metering valve 41.
The metering valve 41 is pushed onto the movable valve seat 42 by the second spring 44 via the movable valve seat 42, and the fuel passage 51 provided in the movable valve seat 42 is closed.

Further, the metering valve 41 is pushed by the second spring 44 to form a gap 65 between the metering valve 41 and the armature 48 .

Here, the gap 65 is adjusted by the stopper 50.

The armature 48 is slidably inserted into one side of the center hole of a non-magnetic bobbin 56 around which the coil 47 is wound, and a core 49 is similarly fitted and fixed to the other side of the center hole of the bobbin 56. The armature 48 is connected to a third spring 8 in a cover 59 having a fuel supply hole.
4 is in contact with each other.

The core 49 is fitted and fixed into the casing 72, and has a hole 73 in the center into which the metering valve 41 is fitted, and a hole 73 in which the metering valve 41 is fitted.
A mixing chamber 74 communicating with the fuel injection nozzle 75 is provided, and a base portion of a fuel injection nozzle 75 is fitted and fixed in the mixing chamber 74.

Further, a mixing passage 76 is provided in the center of the injection nozzle 75 in communication with the mixing chamber 74, and a Ron door 8 having a check valve 53 and a fuel injection valve 52 at its tip is inserted into the mixing passage 76. The check valve 53 is always urged to close by the first spring 43.

The first spring 43 is interposed between the nozzle 75 and the retainer 28 having a diaphragm.

A gap 65 is formed between the metering valve 4 and the armature 48 by the second spring 44.

A diaphragm 80 is sealed and clamped between the diaphragm 80 and a dowel member 81 by a seal member 85.

For this reason, the mixing chamber 74 is separated from the fuel chamber 46 by the diaphragm 80.

Further, the fuel passage 51 communicates with a mixing passage 76 via a fuel injection hole 52.

82 is a sealing member, and 83 is an air supply port that is always connected to the mixing chamber 7.
It is connected to 4.

84 is a third spring.

Next, to explain the operation of this embodiment, high-pressure air is constantly supplied to the mixing chamber 74 via the air supply port 83 by an air pump (not shown).

(Measuring process) Here, when a fuel metering current is applied to the coil 47 (solenoid mechanism 5 in Fig. 1), the spring force of the first spring 43 is increased by the second spring 44, so that the armature 48 does not move, only the small metering valve 41,
It is pulled by the armature 48 and moves against the second spring 44.

Therefore, in order for the metering valve 41 to separate from the movable valve seat 42,
The fuel passes between the inner peripheral surface of the hole 73 of the core 49 and the outer surface of the metering valve 41, enters the fuel passage 51, and flows into the mixing passage 76 through the fuel injection hole 52.

(Injection Step) Next, when a fuel injection current is applied to the coil 47 (solenoid mechanism 5 in FIG. 1), the armature 48 is attracted to the core 49 and moves.

At this time, in order to push the movable valve seat 42 against the first spring 43 via the metering valve 41, the rod 78 is pushed, opening the check valve 53, and extending the passage from the mixing chamber 74 to the passage 76 on the outer periphery of the Ron door 8. A mixture of the supplied high-pressure air and the metered fuel is injected from the tip of the open fuel injection nozzle 75.

The above-mentioned FIG. 2 shows the solenoid drive current pattern in the case of FIG. 4. First, a fuel metering current is applied to the coil 47 to move the metering valve 41, thereby supplying fuel to the mixing passage 76 and metering the fuel. Then, by applying a fuel injection current to the coil 47, the armature 48 moves, pushes the fuel injection door 8 through the metering valve 41 and the movable valve seat 42, opens the check valve 53, and injects fuel. The current value level and energization time are specified.

In the above embodiment, compared to the conventional case in which two solenoids are driven separately, only one coil 47 is required, making it possible to downsize the fuel injection device. In addition to being simple, since the fuel is injected with high-pressure air, atomization of the fuel is promoted and combustion is improved, and the current pattern can be directly controlled from the metering process.
Since the injection process is started, the response of the armature 48 is improved, which leads to an improvement in the response of the check valve 53, and it is possible to improve the response of the armature 48 without having to measure the fuel again during the injection process in which the fuel injection current flows. Accurate measurement is possible.

(Effects of the Invention) As described above, according to the present invention, in a fuel injection device suitable for a two-stroke engine, the current pattern is transferred from the metering process to the direct injection process, so the response of the armature is improved. This leads to an improvement in the responsiveness of the check valve, and since it is not necessary to measure the fuel again during the injection process in which the fuel injection current flows, more precise metering can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the metering current and the time of the injection current used to explain Fig. 1, and Fig. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing a mechanical configuration of an embodiment of the fuel injection device of the present invention, and FIG. 5 is a diagram showing an example of a conventional fuel injection device. In the figure, 1... 2... 3... 4... 5... 6... 6a... 6b... 6c... 6d... Metering signal input circuit, injection signal input circuit, Control circuit, switching circuit, solenoid mechanism, current detection section, - Holding current detection section, - Rush current detection section, - Metering current detection section, - Current detection section, - DC-DC converter.

Claims (1)

[Scope of Claims] A control circuit to which a metering signal and a fuel injection signal are input; a mixing passage to which high-pressure air is constantly supplied; a metering current outputted by the control circuit based on the metering signal; a fuel metering device that supplies a metered amount of fuel to the mixing passage; and a fuel that is actuated by a fuel injection current output by the control circuit based on the fuel injection signal and injects the fuel supplied to the mixing passage together with the high-pressure air. injection means, the metering current and the fuel injection current are continuously output, and the value of the fuel injection current is greater than the value of the metering current, and the fuel metering means and the fuel injection means are A fuel injection device characterized in that it is driven by the same solenoid mechanism.