JP3036035B2 - Fuel injection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device, and more particularly to a fuel injection device applied to a two-stroke engine.

(Prior art) Until now, two-cycle engines have been developed by various manufacturers in order to cope with miniaturization, high output, low fuel consumption, and low vibration of the engine. It cannot be said that the requirements are sufficiently satisfied, and the current situation is that a conventional fuel injection device for a four-cycle engine is changed and used for a two-cycle engine.

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

In the fuel supply device of the publication, the fuel is introduced into the air while being measured to form a mixture of fuel and air, or the fuel gas mixture is supplied at regular time intervals with respect to the engine cycle.
It is disclosed to supply to institutions.

FIG. 5 shows a fuel supply device for an internal combustion engine proposed in Japanese Patent Application Laid-Open No. 62-93481, in which fuel is supplied from a fuel tank 135 to an injector 130 via a pump 136.

The chamber 132 is configured to inject measured fuel from the 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.

(Problems to be Solved by the Invention) However, in the fuel injection device shown in FIG.
In this method, there is a step of injecting fuel into the high-pressure air chamber 132 by activating the solenoid of the fuel measuring unit 0, and another step of activating the other solenoid 131. Are not only large, but also
There is a disadvantage that the control method becomes complicated.

Further, in the conventional apparatus, etc., it is not possible to accurately detect the current corresponding to the measurement and injection of the fuel, so that even if an abnormality occurs in the fuel measurement or the fuel injection mechanism, it is quickly determined which part is abnormal. I couldn't do that.

(Means and Actions for Solving the Problems) Therefore, the present invention has been made in view of the above-mentioned disadvantages, and is a fuel injection device particularly suitable for a two-cycle engine, in which a measurement signal and a fuel injection signal are input. A control circuit, a mixing passage to which high-pressure air is constantly supplied, fuel metering means which is operated by a metering current output by the control circuit based on the metering signal, and supplies the measured fuel to the mixing passage; A fuel injection means which is operated by a fuel injection current output from the control circuit based on an injection signal and injects fuel supplied to the mixing passage together with the high-pressure air, wherein the metering current and the fuel injection current are continuous. And the value of the fuel injection current is greater than the value of the metering current, so that the fuel metering means and the fuel injection means have the same solenoid mechanism. It is driven by

Therefore, since the current pattern is shifted directly from the metering process to the injection process, the response of the armature is improved, which leads to the improvement of the responsiveness of the check valve. Can be defined accurately.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIG. 1 and FIG.

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

Reference numeral 5 denotes a solenoid mechanism which operates a metering valve and a fuel injection valve by operating this valve.

Reference numeral 6 denotes a current detection unit, which includes a holding current detection unit 6a, an inrush current detection unit 6b, a weighing current detection unit 6c, and a current detection unit 6d, and detects a current flowing to the solenoid mechanism 5.

Reference numeral 7 denotes a DC-DC converter which boosts a power supply (battery) voltage to a predetermined voltage.

FIG. 2 shows the fuel metering current and the fuel injection current flowing through the solenoid mechanism 5, and the metering current of the fuel injection current having a larger current value than the fuel metering current is continuous with the fuel metering current.

In FIG. 2, A1 and A2 indicate the fuel metering current, and A3 to A5 indicate the fuel injection current. At time T1 of the fuel metering current, the current value becomes I1, the fuel injection current becomes the current value I2, and the peak current becomes And the fuel injection current becomes the current value I3 during the time T2.

Here, T4 is a time for the fuel measuring current to rise to the current value I1, and T5 is a time for the fuel injection current to fall from I3.

FIG. 3 is a diagram showing an example of a specific circuit configuration of FIG.
Corresponding to the block diagram of FIG. 1, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

Hereinafter, a control method of the solenoid mechanism 5 will be described in detail.

The output signal 100 of the fuel metering signal input circuit 1 is the control circuit 3
Is input to the control circuit 3, the control circuit 3 operates the switching circuit 4 to start flowing a current from the DC-DC converter 7 to the solenoid mechanism 5, the switching circuit 4, and the ground E rapidly (A1 shown in FIG. 2). .

This current is constantly detected by the current detection unit 6d,
The output signal of the current detector 6d is input to the weighing current detector 6c.

Here, when the metering current detector 6c determines that the current value flowing through the solenoid mechanism 5 reaches I1 in FIG. 2, the time T indicated by the output signal 100 of the fuel metering signal input circuit 1 is equal to the time T.
The current value I1 continues to flow through the solenoid mechanism 5 by 1 (A2 shown in FIG. 2).

This time T1 can take any time, and the longer the metered fuel, that is, the more fuel injection, the longer the time T1.

With the above, the fuel measuring step is completed, and then the process proceeds to the fuel injection step.

An output signal of the fuel metering signal input circuit 1 is provided to the control circuit 3.
The output signal 101 of the fuel injection signal input circuit 2 is input continuously from 100.

As a result, a current larger than the current value I1 starts to flow through the solenoid mechanism 5 (A3 shown in FIG. 2).

At this time, the output signal of the current detector 6d is
Entered in 6b.

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

Thereafter, the output signal of the current detector 6d is
Entered in 6a.

Then, the current value I2 is supplied to the solenoid mechanism 5 for the time T2 specified by the output signal 101 of the fuel injection signal input circuit 2.
(A5 shown in FIG. 2).

 This T2 can take any time.

As described above, the fuel injection step is completed, and the control circuit 3 stops the switching circuit 4, so that the value of the current flowing through the solenoid mechanism 5 becomes zero.

Therefore, in the present embodiment, the current pattern flowing through the solenoid mechanism 5 is directly shifted from the fuel measuring step to the fuel injection step, so that the responsiveness of the armature 48 in FIG. 4 of the solenoid mechanism 5 is improved.

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

Next, a mechanical configuration of an embodiment of the fuel injection device of the present invention will be described with reference to FIG.

Reference numeral 41 denotes a measuring valve made of a magnetic material, and reference numeral 42 denotes a movable valve seat disposed coaxially with the measuring valve 41 so as to be able to freely contact and separate therefrom.

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

The measuring valve 41 is pushed by the second spring 44,
A gap 65 is formed between the armature and the armature.

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

The armature 48 is slidably inserted into one side of the center hole of the non-magnetic bobbin 56 around which the coil 47 is wound,
Similarly, a core 49 fitted and fixed to the other side of the center hole of the bobbin 56.
The armature 48 is in contact with a cover 59 having a fuel supply hole 58 by a third spring 84.

The core 49 is fitted and fixed in the casing 72,
A hole 73 in which the metering valve 41 is fitted and a mixing chamber 74 communicating with the hole 73 are provided at the center, and a fuel injection nozzle is provided in the mixing chamber 74.
75 bases are inserted and fixed.

A mixing passage 76 is provided at the center of the injection nozzle 75 in communication with the mixing chamber 74, and a rod 78 having a check valve 53 and a fuel injection valve 52 at the tip is inserted into the mixing passage 76. The check valve 53 is always urged to be closed by the first spring 43.

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

The metering valve 41 is provided with an armature 48 by a second spring 44.
Is formed between them.

Reference numeral 80 denotes a diaphragm. The outer peripheral portion of the diaphragm 80 is sandwiched and fixed between the core 49 and the fuel injection nozzle 75, and the inner peripheral portion is a sealing member between the retainer 28 and the holder member 81.
Sealed and fixed by 85.

For this reason, the mixing chamber 74 is formed by the diaphragm 80 in the fuel chamber 46.
It is sectioned.

Further, the fuel passage 51 is provided with a mixing passage through a fuel injection hole 52.
Communicates with 76.

82 is a seal member and 83 is an air supply port which is always in communication with the mixing chamber 74.

 84 is a third spring.

Next, the operation of the present embodiment will be described. The high-pressure air fed to the mixing chamber 74 by an air pump (not shown) is constantly supplied through the air supply port 83.

(Measurement Step) Here, when a fuel measurement current is supplied to the coil 47 (the solenoid mechanism 5 in FIG. 1), the spring force of the first spring 43 is increased by the second spring 44. Without movement, only the small metering valve 41 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 gas passes through the space 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 passes through the fuel injection hole 52 to the mixing passage. Flow into 76.

(Injection Step) Next, when a fuel injection current is applied to the coil 47 (the 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 to open the check valve 53, and from the mixing chamber 74 to the passage 76 on the outer periphery of the rod 78. A mixture of the supplied high-pressure air and the measured fuel is injected from the tip of the opened fuel injection nozzle 75.

FIG. 2 described above shows the solenoid drive current pattern in the case of FIG. 4. First, a fuel metering current is supplied to the coil 47 to move the metering valve 41, thereby supplying fuel to the mixing passage 76 and metering the fuel. Then, by passing a fuel injection current through the coil 47, the armature 48 moves and pushes the fuel injection rod 78 via the metering valve 41 and the movable valve seat 42 to check the check valve 53.
And the level of the current value and the energizing time in the state of injecting the fuel are defined.

In the above embodiment, since only one coil 47 is required as compared with the case where two solenoids are separately driven as in the related art, the size can be reduced, and the driving circuit of the fuel injection device is required. In addition to simplification, the fuel is injected with high-pressure air, which promotes finer fuel and improves combustion.
Since the process shifts to the injection process, the response of the armature 48 is improved, which leads to an improvement in the responsiveness of the check valve 53. Precise weighing is possible.

(Effects of the Invention) As described above, according to the present invention, in the fuel injection device suitable for a two-cycle engine, the current pattern is shifted directly from the measurement process to the injection process, so that the response of the armature is improved, and This leads to an improvement in the responsiveness of the check valve, and it is not necessary to measure the fuel again in the injection step of flowing the fuel injection current, so that more precise measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a relationship between a measuring current and a time of an injection current used for explaining FIG. 1, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing a mechanical configuration of one 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 drawing, 1 ... weighing signal input circuit, 2 ... injection signal input circuit, 3 ... control circuit, 4 ... switching circuit, 5 ... solenoid mechanism, 6 ... current detection unit, 6a ... holding current Detector, 6b rush current detector, 6c weighing current detector, 6d current detector, 7 DC-DC converter.

Continuation of front page (56) References JP-A-62-218638 (JP, A) JP-A-2-185649 (JP, A) JP-A-63-314363 (JP, A) JP-A-2-87959 (JP) , U) Japanese Utility Model Showa 63-21770 (JP, U) Japanese Utility Model Showa 64-34464 (JP, U) Tokuyo Sho 63-501091 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB (Name) F02D 41/34 F02D 41/20

Claims (1)

(57) [Claims] 1. 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, and a metering current output by the control circuit based on the metering signal to operate the mixing. Fuel metering means for supplying the measured fuel to the passage; fuel injection which is operated by a fuel injection current outputted 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 Means, wherein the metering current and the fuel injection current are continuously output, and 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 the same. And a fuel injection device driven by the solenoid mechanism.