JPH03279669A - Fuel injection device - Google Patents

Abstract

PURPOSE:To miniaturize the device and obtain a favorable condition of combustion by inserting and fixing a core on one side of the center hole of a bobbin wound with a coil, and arranging an armature on the other side of the center hole of the bobbin. CONSTITUTION:When a low current is supplied to a coil 7, an armature 8 is moved in the core 9 direction until a metering valve 1 abuts to a stopper 2. Therefore fuel flows in a mixing chamber 6 through a fuel passage 5. Next, when a high current is supplied to the coil 7, a non-return valve 12 in one body with the stopper 2 is opened, mixture of high pressure air from an air supply port 20 and fuel is injected from the extreme end opening part of an injection nozzle 17. In this way, coil is enough to be one and the device can be miniaturized. Further, favorable combustion can be obtained.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a fuel injection device for an internal combustion engine.

(Conventional technology) In response to the demands for smaller, high-output, low fuel consumption, and low-vibration engines, various manufacturers are developing two-cycle engines, but a fuel injection system suitable for two-stroke engines has yet to be developed. Since the requirements cannot be said to be fully met, the current situation is that the conventional four-cycle fuel injection system is modified to be used for two-stroke applications.

FIG. 3 shows a fuel supply system for an engine conventionally proposed in Japanese Unexamined Patent Publication No. 62-93481, in which fuel is supplied from a fuel tank 35 to a known injector 30 via a pump 36. Further, high pressure air is supplied from an air source 37 to a chamber 32, and an injector 3 is supplied to this chamber 32.
The system injects a pre-metered amount of fuel from zero.

Thereafter, the solenoid 31 is actuated to open the valve 33, so that fuel is injected from the injection hole 34 together with high pressure air.

(Problems to be Solved by the Invention) In the conventional device shown in FIG. The system consists of two processes: activating the fuel pump and injecting the fuel to the outside, but this method requires two solenoids, which not only increases the size of the main unit but also makes the control method complicated. It had some drawbacks.

The present invention aims to provide a fuel injection device that includes one solenoid and is suitable for a two-stroke engine.

[Structure of the invention]

(Means for Solving the Problems) Therefore, the present invention provides a method for inserting and fixing a core into one side of the center hole of a bobbin around which a coil is wound, and at the same time, leaving a gap between the core and the other side of the center hole of the bobbin. a slidable armature biased away from the core, a mixing chamber being formed between the core and an injection nozzle fixed thereto, and a fuel passage communicating with the mixing chamber. A metering valve is provided in the core, a mouth/throat is inserted into the fuel passage, one end of the rod is fixed to the armature, and the other end is provided with a metering valve that normally closes the fuel passage, and the metering valve direction A stopper energized by the metering valve but always separated from the metering valve is disposed in the mixing chamber, and a rod having one end fixed to the stopper and a check valve provided at the other end is connected to the injection nozzle. When inserted into the injection passage, the end of the injection passage is normally closed by the check valve, and the biasing force of the stopper is greater than the biasing force of the armature (and high pressure air is constantly supplied to the mixing chamber). It is equipped with an air supply port, and is used as a means to solve the problem.

(Operation) First, when a low current is applied to the coil, the armature moves toward the core until the metering valve hits the stopper. Therefore, the metering valve opens the opening of the fuel passage on the side of the mixing chamber, so that fuel flows into the mixing chamber through the fuel passage.

Next, when a high current is applied to the coil, the metering valve first moves against the biasing force of the armature, causing instantaneous communication between the fuel passage and the mixing chamber, and the armature is attracted to the core and moves further. . Therefore, the metering valve pushes the stopper until the armature comes into contact with the core, so the reverse valve integrated with the stopper opens, and high-pressure air and fuel from the air supply port that had flowed from the mixing chamber to the injection passage around the rod's outer circumference are released. The air-fuel mixture is injected from the opening at the open end of the injection nozzle. The amount of fuel injected at this time is the sum of the amount measured in the low current operation and M (a very small constant amount) added by the instantaneous opening of the metering valve during the high current operation.

(Embodiment) The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 shows an embodiment of the fuel injection device of the present invention, in which 1 is a metering valve, 2 is a movable switch of the metering valve 1 It's a spittle. 15 is a rod, one end of which is fixed to the armature 8, and the metering valve 1
The other end of the rod 15 is fixed to. The armature 8 is urged in a direction away from the core 9 by the second spring 4 so that a gap 11 is formed between the body 18 and the core 9, which is formed by a cylindrical structure. The second spring 4 is disposed between steps formed on the armature B and the body 18, respectively. Further, a fuel passage 5 into which a rod 15 is inserted is formed in the center of the core 9 of the body 18, and the upper part of the rod 15 has a stopper 13 integral therewith.
is press-fitted and fixed into the center of the armature 8 while in contact with the armature 8. Further, a fuel injection nozzle 17 is fitted into the body 18 through a sealing material 22 in an air-liquid tight manner, and a mixing chamber 6 is formed between the nozzle 17 and the body 18.

The stopper 2 biased toward the metering valve 1 by the first spring 3 is disposed in the mixing chamber 6, and the metering valve 1 controls opening and closing of the mixing chamber 6 and the fuel passage 5. Ori,
The upper end of a rod 14 inserted into the injection passage 21 of the injection nozzle 17 is fixed to the stopper 2 by caulking.

Further, a check valve 12 is formed at the tip of the rod 14, and the check valve 12 always closes the tip opening of the injection passage 21 by the biasing force of the first spring 3. That is, the rod 14 fixed to the stopper 2 is urged in the direction of the metering valve 1 by the first spring 3. Note that the spring force of the first spring 3 is set larger than that of the second spring 4. The armature 8 is slidably inserted into the center hole of a non-magnetic bobbin 24 around which the coil 7 is wound, and is in contact with the cover 16 so that it cannot rise any further. Further, the core 9 is inserted into the lower part of the center hole of the pobbin 24. Reference numeral 20 denotes an air supply port provided in the pipe 19, which is always in communication with the mixing chamber 6. 23 is a fuel supply port.

Next, the operation will be described. The mixing chamber 6 is constantly supplied with high-pressure air from the air supply port 20, which is pumped by an air pump (not shown).

First, the measuring process will be explained.

In this case, a low current is passed through the coil 7. This allows the first
Since the spring force of the second spring 3 is greater than that of the second spring 4, the armature 8 moves in the direction of the core 9 until the metering valve 1 hits the stopper 2. Therefore, the metering valve 1 is moved away from the body 18 and the opening of the fuel passage 5 on the mixing chamber 6 side is opened, so that fuel passes through the fuel supply port 23, the groove 8a on the side surface of the armature 8, the gap 11, and the fuel passage 5. It flows into the mixing chamber 6.

Next, the injection process will be explained.

In this case, a high current is passed through the coil 7. As a result, first, the metering valve 1 moves in the valve opening direction against the second spring 4, so that the fuel passage 5 and the mixing chamber 6 are instantaneously communicated, and the armature 8 is attracted to the core 9 and further Moving. Therefore, the stopper 1 is integrated with the rod 15.
3 contacts the core 9, the metering valve 1 pushes the rod 14 through the stopper 2 against the first spring 3, so the check valve 12 opens, and the injection of the outer periphery of the rod 14 from the mixing chamber 6 occurs. The mixture of high pressure air and fuel from the air supply port 20 that has flowed out to the passage 21 is injected from the open end opening of the injection nozzle 17. The amount of fuel to be injected at this time is the sum of the amount measured in the low current operation and M (minor amount) added by the instantaneous opening of the metering valve 1 during the high current operation.

FIG. 2 shows the solenoid drive current pattern in the case of FIG. 1. First, a small current is applied to the coil 7 to move the metering valve 1, thereby supplying fuel to the mixing chamber 6 and metering the fuel.
Next, by applying a large current to the coil 7, the rod 15 is moved until the stopper 13 integrated with the armature 8 comes into contact with the core 9, and the stopper 2 is moved through the metering valve 1.
The current value level and energization time in a state where the check valve 12 is opened by moving the rod 14 and fuel is injected are shown.

〔Effect of the invention〕

Since the present invention is configured as explained in detail above,
Compared to the conventional method in which two solenoids are driven separately, only one coil is required, thus making it possible to downsize. Further, the drive circuit for the fuel injection device can be simplified, and since the fuel is injected with high-pressure air, atomization of the fuel is promoted, and a good combustion state can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a fuel injection device showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the current pattern of FIG. 1, and FIG.
The figure is a front sectional view showing an example of a conventional fuel injection device. Explanation of the main parts of the figure - Metering valve 2 - Stopper 3 - First spring 4 - Second spring 5 - Fuel passage 6 - Mixing chamber 7 - Coil 8 - Armature 9 - Core 0 11 - Gap 13 - Stopper 15 - Rod 17 - Injection nozzle 19 - Pipe 21 - Injection passage 23 - Fuel supply port check valve Rod Caher body Air supply port Seal material bobbin 1

Claims (1)

[Claims] A core is inserted and fixed into one side of a center hole of a bobbin around which a coil is wound, and a slidable member is biased in a direction away from the core to the other side of the center hole of the bobbin with a gap between the core and the core. disposing an armature, forming a mixing chamber between the core and an injection nozzle fixed to the armature, providing a fuel passage communicating with the mixing chamber in the core, and inserting a rod into the fuel passage; One end of the rod is fixed to the armature, and the other end is provided with a metering valve that normally closes the fuel passage, and is biased in the direction of the metering valve but is normally separated from the metering valve. A stopper is disposed in the mixing chamber, and a rod having one end fixed to the stopper and a check valve provided at the other end is inserted into the injection passage of the injection nozzle, and the check valve normally controls the injection passage. A fuel injection device, characterized in that the tip is closed, the biasing force of the stopper is made larger than the biasing force of the armature, and an air supply port is provided for constantly supplying high-pressure air to the mixing chamber.