JP2814675B2 - Fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a fuel injection device for an internal combustion engine.

(Prior art) Two-cycle engines have been developed by various manufacturers in response to demands for smaller, higher-output, lower fuel consumption, and lower vibration of the engine. However, a fuel injection device suitable for a two-cycle engine is still insufficient. Since it cannot be said that the requirements are satisfied, the current situation is that a conventional four-cycle fuel injection device is changed to two-cycle fuel injection.

FIG. 3 shows an apparatus for supplying fuel to an engine proposed in Japanese Patent Application Laid-Open 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 the chamber 32, and the fuel metered in advance from the injector 30 is injected into the chamber 32. Then solenoid 31
Operates to open the valve 33, whereby fuel is injected from the injection hole 34 together with high-pressure air.

(Problem to be Solved by the Invention) In the conventional apparatus shown in FIG. 3, a step of injecting fuel into the high-pressure air chamber 32 by operating a solenoid (not shown) of the fuel measuring section of the injector 30 and another solenoid 31 Actuating the fuel to inject fuel to the outside
Although there are two steps, in such a method, since two solenoids are arranged, there is a disadvantage that not only the main body becomes large, but also the control method becomes complicated.

SUMMARY OF THE INVENTION The present invention provides a single-solenoid fuel injection device suitable for a two-cycle engine.

[Configuration of the invention]

(Means for Solving the Problems) In order to solve the above problem, the present invention is directed to a bobbin on which a coil is wound, wherein a core is inserted into and fixed to one side of a center hole of the bobbin, and the other side of the center hole of the bobbin is spaced from the core. A slidable armature urged away from the core, a mixing chamber is formed between the core and an injection nozzle fixed thereto, and a fuel passage communicating with the mixing chamber is formed. A metering valve is provided in the core, a rod is inserted into the fuel passage, one end of the rod is fixed to the armature, and a metering valve is provided at the other end, which always closes the fuel passage. A stopper which is biased but is 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 passage of the injection nozzle. And always check the injection passage by the check valve. The tip is closed, and the urging force of the stopper is made larger than the urging force of the armature, and an air supply port for constantly supplying high-pressure air to the mixing chamber is provided. Means.

(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 opening of the fuel passage on the mixing chamber side is opened by the metering valve, so that the fuel flows into the mixing chamber through the fuel passage.

Next, when a high current is applied to the coil, first, the metering valve moves against the urging force of the armature, so that the fuel passage and the mixing chamber are instantaneously communicated, and the armature is sucked by the core and further moved. . Therefore, since the metering valve pushes the stopper until the armature contacts the core, the check valve integrated with the stopper is opened, and the high-pressure air and fuel from the air supply port flowing out of the mixing chamber to the injection passage on the rod outer periphery are opened. Is injected from the opening at the tip of the opened injection nozzle. The fuel injection amount at this time is an added value of the amount measured by the low current operation and the amount (fine-quantitative) added by the instantaneous opening of the metering valve during the high current operation.

(Embodiments) The present invention will be described below with reference to the embodiments in the drawings.
The figure shows an embodiment of the fuel injection device of the present invention, in which 1 is a metering valve, and 2 is a movable stopper of the metering valve 1. Reference numeral 15 denotes a rod, one end of which is fixed to the armature 8, and the other end of the rod 15 is fixed to the metering valve 1. The armature 8 is urged by the second spring 4 in a direction away from the core 9 so that a gap 11 is formed between the body 18 and the core 9 formed integrally. The second spring 4 is disposed between steps formed on the armature 8 and the body 18, respectively. In the center of the core 9 of the body 18, a rod 15
A fuel passage 5 into which the rod 15 is inserted is formed.
The upper part is press-fitted and fixed to the center of the armature 8 with a stopper 13 integral with the armature 8 in contact with the armature 8. A fuel injection nozzle 17 is fitted and fixed to the body 18 in a gas-liquid tight manner via a sealing material 22.
Mixing chamber 6 is formed between 17 and body 18.

The stopper 2 urged toward the metering valve 1 by the first spring 3 is provided in the mixing chamber 6, and the metering valve 1 controls opening and closing of the mixing chamber 6 and the fuel passage 5. The upper end of the rod 14 inserted into the injection passage 21 of the injection nozzle 17 is fixed to the stopper 2 by swaging. A check valve 12 is formed at the tip of the rod 14, and the check valve 12 always closes the opening at the tip of the injection passage 21 by the urging force of the first spring 3. That is,
The rod 14 fixed to the stopper 2 is the first spring 3
Urges in the direction of the metering valve 1. Note that the first spring 3 is set to have a larger spring force than the second spring 4. Armature 8 is coil 7
Is slidably inserted in the upper portion into the center hole of the non-magnetic bobbin 24 around which is wound, and is in contact with the cover 16 so that it cannot be further raised. The core 9 is a bobbin
It is inserted in the lower part of 24 center holes. Reference numeral 20 denotes an air supply port provided in the pipe 19, which is always in communication with the mixing chamber 6. twenty three
Is a fuel supply port.

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

 First, the measuring step will be described.

In this case, a low current is applied to the coil 7. Thus, the spring force of the first spring 3 is reduced by the second spring 4.
Due to the larger size, the armature 8 moves in the direction of the core 9 until the metering valve 1 hits the stopper 2. Accordingly, since the metering valve 1 is separated from the body 18 and the opening of the fuel passage 5 on the side of the mixing chamber 6 is opened, the 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 step will be described.

In this case, a high current is applied to 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 connected, and the armature 8 is sucked into the core 9 as it is, and Moving. Therefore, the stopper 13 integrated with the rod 15
The check valve 12 is opened because the metering valve 1 pushes the rod 14 through the stopper 2 against the first spring 3 until the abutment with the core 9 causes the injection passage from the mixing chamber 6 to the outer periphery of the rod 14. The mixture of high-pressure air and fuel from the air supply port 20 that has flowed out to 21 is injected from the opening at the end of the injection nozzle 17 that has been opened. The fuel injection amount at this time is an added value of the amount measured by the low current operation and the amount (fine-quantity) added by the instantaneous opening of the metering valve 1 during the high current operation.

FIG. 2 shows a solenoid drive current pattern in the case of FIG. 1. First, a small current is supplied to the coil 7 and the metering valve 1 is moved to supply fuel to the mixing chamber 6 and measure the fuel. When a large current flows through the rod 7, the rod 15 moves until the stopper 13 integral with the armature 8 comes into contact with the core 9, so that the stopper 2
And the rod 14 is moved to open the check valve 12, and the level of the current value and the energizing time in a state where the fuel is injected are shown.

[Effects of the Invention] As described in detail above, the present invention is configured, so that only one coil is required, compared with a conventional configuration in which two solenoids are separately driven, and thus the size is reduced. Enable. Further, the drive circuit of the fuel injection device can be simplified, and the fuel is injected with high-pressure air, so that the atomization of the fuel is promoted and a favorable combustion state can be obtained.

[Brief description of the 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 a current pattern of FIG.
FIG. 1 is a front sectional view showing an example of a conventional fuel injection device. Description of main parts in the drawing 1... Metering valve 2... Stopper 3... 1st spring 4... 2nd spring 5... Fuel passage 6... Mixing chamber 7... Coil 8. , 9 ... core 11 ... gap, 12 ... check valve 13 ... stopper, 14 ... rod 15 ... rod, 16 ... cover 17 ... injection nozzle, 18 ... body 19 ... pipe, 20 ... Air supply port 21 ... Injection passage, 22 ... Sealing material 23 ... Fuel supply port, 24 ... Bobbin

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-93481 (JP, A) JP-A-63-284965 (JP, A) JP-A-1-271658 (JP, A) JP-A-3-3 217653 (JP, A) JP-A-3-43662 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 67/02 F02M 67/12 F02M 51/06 F02M 69/04 F02M 69/00 F02M 51/00 F02M 61/08

Claims (1)

(57) [Claims] A core is inserted into and fixed to one side of a center hole of a bobbin around which a coil is wound, and is urged in a direction away from the core to the other side of the center hole of the bobbin with a gap from the core. A slidable armature is disposed, a mixing chamber is formed between the core and the injection nozzle fixed thereto, and a fuel passage communicating with the mixing chamber is provided in the core, and the fuel passage is provided in the fuel passage. A rod is inserted, one end of the rod is fixed to the armature, and a metering valve that always closes the fuel passage is provided at the other end, and is biased in the direction of the metering valve. A stopper that is always separated is disposed in the mixing chamber, and one end is fixed to the stopper, and a rod provided with a check valve at the other end is inserted into the injection passage of the injection nozzle, and the check valve is always To close the tip of the injection passage, and With the biasing force of the path larger than the urging force of the armature, the fuel injection apparatus characterized by comprising an air supply port for supplying the constant high pressure air into the mixing chamber.