JP2524045Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to an air blast type fuel injection device having a fuel control valve and an air control valve. is there.

[Conventional technology]

Conventionally, in an internal combustion engine using gasoline as fuel, an automatic valve, an air control valve for controlling compressed air for opening and closing the automatic valve, and a fuel for enabling the fuel to be directly injected into the in-cylinder combustion chamber, There is known an air blast type fuel injection device including a fuel control valve for metering fuel.

FIG. 6 shows the air blast type fuel injection device 10 disclosed in Japanese Patent Application Laid-Open No. Sho 62-3168. In the figure, an injection space communicating with a fuel chamber 27 of an engine via an automatic valve 18 is shown.
An air control valve 16 for injecting compressed air for opening the automatic valve 18 and a fuel control valve 15 for metering fuel are arranged in the injection space 33 so as to open.
In the present device, both the fuel pumped by the fuel pump 41 and the air compressed by the air compressor 42 are injected by applying a set voltage pulse by the electronic control unit 40. At this time, the fuel is first injected into the injection space 33 and stored in the space 33. Thereafter, air is injected into the injection space 33, and the pressure at this time opens the automatic valve 18, so that the fuel stored in the space 33 is directly injected into the combustion chamber 27 together with the air.

[Problems to be solved by the invention]

In a conventional air blast type fuel injection device, when performing fuel metering injection from the fuel control valve 15,
In order to be injected into the sealed injection space 33,
The back pressure on the fuel control valve 15 increases, and as a result, the flow rate characteristic of the fuel does not become linear as shown by the broken line B in FIG. In addition, since the sealed injection space 33 communicates with the in-cylinder combustion chamber via the automatic valve 18, fluctuations in the in-cylinder pressure of the operating engine directly affect the pressure in the injection space, and as a result, the amount of injected fuel is reduced. It causes large fluctuations in flow characteristics.

[Means for solving the problem]

In order to solve the above problems, in the present invention, an air control valve for injecting compressed air for opening the automatic valve is provided with an injection space communicating with a combustion chamber of an internal combustion engine via an automatic valve. A fuel control valve for metering and injecting fuel is disposed so as to open to the injection space, and after the fuel control valve performs metering injection of fuel and closes the fuel control valve, the compressed air is controlled by the air control valve. In the air blast type fuel injection device for supplying the pressure, the pressure in the injection space is adjusted to include the time when the fuel is injected by the fuel control valve except for the compressed air supply for the automatic valve opening. During the period, lower than the valve opening pressure of the automatic valve,
A fuel injection device for an internal combustion engine, comprising: means for adjusting a pressure to a predetermined value higher than the atmospheric pressure.

[Action]

The fuel control valve opens to perform metered injection of fuel into the injection space. Since the air pressure at this time is lower than the opening pressure of the automatic valve, the automatic valve remains in the closed state, and fuel is accumulated in the injection space. After the fuel control valve is closed, the air control valve is opened, and when the compressed air is discharged into the injection space, the air pressure in the injection space rises, and the pressure is pushed by this pressure to open the automatic valve, and the fuel is compressed. It is injected directly into the combustion chamber in the cylinder of the engine from the automatic valve together with the air. After the injection is completed, the air control valve closes,
The pressure in the injection space is maintained at a predetermined positive pressure lower than the valve opening pressure of the automatic valve and higher than the atmospheric pressure by the pressure regulating mechanism.
Subsequently, the next metered injection of fuel is performed according to the rotation of the engine.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIGS. 3 and 4 show an example of a state in which the fuel injection device 10 according to the present invention is mounted on a cylinder head 20 of a two-cycle internal combustion engine. 21 is a cylinder block, 22 is a spark plug. This two-stroke internal combustion engine is a four-valve type having two intake valves 23 and two exhaust valves 24, 25 is an intake port, and 26 is an exhaust port. The main body 11 of the fuel injection device 10 is fastened and fixed to the cylinder head 20 by bolts 12, and the tip nozzle 13 of the fuel injection device 10 opens directly toward the combustion chamber 27 of the engine. Reference numeral 14 denotes a delivery pipe which distributes fuel and air to the fuel control valve 15 and the air control valve 16 at a predetermined pressure, respectively.

FIG. 2 is a cross-sectional view showing the configuration of
A holder 17 is provided at the tip of the automatic valve 18, and an automatic valve 18 is provided at the tip. The automatic valve 18 is normally closed by a spring 30, but when compressed air pressure is applied, the spring 30 is closed.
Is compressed, the tip of the automatic valve 18 pops out and opens,
Fuel and air are injected into the combustion chamber 27 from the tip nozzle 13.
The fuel control valve 15 has a fuel injection nozzle 31 at one end. The injection nozzle 31 is normally closed by a needle 32, but is controlled by an electronic control unit (not shown) and is driven by an electromagnetic drive (not shown) when an electric signal is given. When the mechanism operates, the needle 32 is lifted, and fuel is injected from the injection nozzle 31 into the injection space 33. The nozzle 31 has a hole type. This fuel is supplied to the nozzle 31 and the automatic valve in the injection space 33.
The fuel is temporarily stored in a fuel injection space 33a that is a fuel passage between the fuel injection space 18 and the fuel injection space 18. 14 is a fuel and air delivery pipe,
The delivery pipe 14 has a fuel passage 34 connected to a fuel supply source (not shown) and an air passage 35 connected to a compressed air supply source (not shown). The fuel receiving end of the fuel control valve 15 is connected to the fuel passage 34.

An air control valve 16 is provided in parallel with the fuel control valve 15, and its structure is basically the same as the structure and configuration of a conventional fuel injector, and includes an electromagnetic valve (not shown).

After a predetermined time has elapsed after the fuel control valve 15 has been closed, an electric signal controlled by an electronic control unit (not shown) is given to the air control valve 16 to open the valve.
Compressed air is injected into the injection space 33 from the injection space 33, and the automatic valve 18 is opened by the air pressure.The fuel stored in the injection space 33 until then is compressed with the compressed air from the automatic valve 18 to the combustion chamber.
Injected directly into 27.

1 (a) and 1 (b) show an embodiment of the present invention. FIG. 1 (a) shows the fuel control valve 15 in the fuel injection device 10.
2 shows a partially enlarged cross-sectional view of the air control valve 16. Air control valve 16
Is provided with a valve 1 having a pin 2 which, when closed, comes into contact with the valve seat 3 in FIG.
Leave when opening the valve. The figure shows the state when the valve is opened. A second valve seat 4 is provided at the end of the pin 2, and a spring 6 presses a steel ball 5 against the valve seat 4. An air injection space in the injection space 33 is provided between the steel ball 5 and the valve 1.
A pressure leak hole 8 is provided on the spring 6 side, and a pressure check valve 9 is attached to the tip of the pressure leak hole 8. Set pressure adjusting member at the end of pressure check valve 9
39 is provided, and a spring is
38 are interposed.

FIG. 1B is an enlarged view of a portion E in FIG. 1A.
FIG. 1 (b) shows that the valve 1 and the steel ball 5
The state when the valve 1 is closed is represented by a solid line 1a, the position of the steel ball at that time is represented by 5a, the state when the valve 1 is opened is represented by a broken line 1b, and the position of the steel ball at that time is represented by 5b. Therefore, FIG.
It matches the condition of b, 5b.

Next, the operation of the fuel injection device having the above configuration will be described. In this device, the fuel control valve 15 and the air control valve 16
However, no drive signal is applied at the same time. That is, one of the control valves from the electronic control unit (not shown),
The drive signal is applied alternately at a certain time at 15 or 16. If the air control valve drive signal is not applied,
The valve 1 contacts the first valve seat 3 and shuts off the compressed air passage. See FIG. 1 (b), 1a. At the same time, the pin 2 pushes the steel ball 5, whereby the steel ball 5 is separated from the second valve seat 4. Thereby, the injection space 33 communicates with the pressure leak hole 8. See FIG. 1 (b), 5a. There is a pressure check valve 9 in front of it. When the pressure in the injection space 33 is equal to or higher than the set pressure of the pressure check valve 9, the pressure check valve is pushed and opened to discharge air of an extra pressure to the outside atmosphere. The pressure in the injection space 33 is constantly maintained at a predetermined set pressure set by the pressure check valve 9. This set pressure is lower than the valve opening pressure of the automatic valve 18,
The positive pressure is higher than the atmospheric pressure. When in this state,
A drive signal to the fuel control valve 15 is applied. This allows
When the fuel is injected from the fuel control valve into the injection space 33, the pressure in the injection space 33 increases again. At this time, the pressure check valve 9 operates to reduce the pressure to the set pressure. The accompanying pressure increase in the injection space 33 is prevented, and the fuel injection is always performed under a predetermined set value.Therefore, since the fuel is not injected into the sealed injection space as in the conventional example, Back pressure does not rise. At this time, since the pressure in the injection space does not rise, the automatic valve 18
(FIG. 2) does not open and remains closed. Next, when the metered injection of the predetermined amount of fuel is completed, the drive signal of the fuel control valve 15 is released, the fuel control valve is closed, and a certain amount of fuel is injected into the injection space 33, particularly, the fuel injection space 33a serving as a fuel passage. Stored inside. Then air control valve 16
When a drive signal is applied to the valve 1, the valve 1 leaves the first valve seat 3 by the attraction force of an electromagnetic coil (not shown), and the compressed air flows from the air passage 35 into the injection space 33 through the air injection space 33b. It is introduced into the fuel injection space 33a. See FIGS. 1 (b) and 1b. At the same time, the steel ball 5 is pressed against the second valve seat 4 by the reaction force of the spring 6 and shuts off the passage between the injection space 33 and the pressure leak hole 8. See FIGS. 1 (b) and 5b. At this time, the spring 6 has a sufficiently strong urging force so that the steel ball 5 is not pushed backward by the pressure of the compressed air and does not leave the second valve seat 4. Therefore, the compressed air does not flow directly to the pressure leak hole 8 side. When the compressed air flows into the fuel injection space 33a, the automatic valve 18 is pushed by the air pressure to open the valve, and the fuel is directly injected into the combustion chamber 27 together with the compressed air.

According to the configuration of the present embodiment, since the set pressure switching valve (steel ball 5, pressure leak hole 8, etc.) can be arranged near the injection space 33, the dead volume in the pressure space does not need to be increased. Thus, the set pressure switching valve is the air control valve 16
The air control valve is closed when the air control valve is open, and opens when the air control valve is closed.

Further, since the predetermined pressure is always maintained in the injection space 33, the supply air amount and the air pressure required for opening the automatic valve 18 are reduced, and the size of the compressor can be reduced.

In addition, by appropriately setting the set value of the switching valve, the rising width of the air pressure up to the automatic valve opening pressure can be reduced, so that the responsiveness is improved.

Further, variations in the operation response of each injector due to variations in the valve opening pressure of the automatic valve 18 and variations in the injection space volume can be absorbed by adjusting the set pressure of the pressure check valve 9.

In the above embodiment, the air pressure in the injection space 33 is always maintained at a constant positive pressure lower than the valve opening pressure of the automatic valve 18 and higher than the atmospheric pressure except when the compressed air is supplied. As a result, the fuel flow rate characteristic does not fluctuate when the fuel is injected into the sealed injection space as in the conventional example.
In addition, it is possible to supply the fuel with high measurement accuracy without being affected by the fluctuation of the in-cylinder pressure of the engine. FIG. 5 shows a comparison diagram of the flow rate characteristics between the conventional example and the present invention. As shown in the drawing, in the conventional example, the back pressure increases because the injection is performed into the sealed space, and as a result, as shown by the broken line B, the injection flow rate (mm) of the fuel injected into the fuel chamber through the automatic valve.
³ / stroke) tends to decrease as the injection time (microsec) becomes longer. However, according to the present invention, the pressure in the injection space is always constant and the back pressure does not change. As shown, the relationship is linear, and a constant rate of injection is always performed.

In the above embodiment, the case of the two-stroke engine has been described.
It is also applicable to cycle engines.

(Effect) By implementing the present invention, the pressure fluctuation in the injection space is reduced, the influence of the in-cylinder pressure is small, the fuel is always injected at a constant rate, and the supply of fuel with high measurement accuracy is directly performed in the cylinder. It can be performed in the combustion chamber, and the operating performance of the engine is improved.

[Brief description of the drawings]

1 (a) is an enlarged sectional view of a main part of an air blast type fuel injection device according to an embodiment of the present invention, FIG. 1 (b) is an enlarged view of a portion E in FIG. 1 (a), and FIG. FIGS. 3 and 4 are cross-sectional views of the fuel injection device of the present invention, showing an example of a state in which the fuel injection device is mounted on an internal combustion engine. FIG. 3 is a plan view of the fuel injection device, and FIG. FIG. 5 is a front view, FIG. 5 is an injection flow rate characteristic diagram of the present invention and a conventional example at the time of fuel metering injection, and FIG. 6 is an explanatory view showing a state in which a conventional air blast type fuel injection device is attached to an internal combustion engine. . 10 ... fuel injection device, 15 ... fuel control valve, 16 ... air control valve, 18 ... automatic valve, 27 ... combustion chamber, 33 ... injection space.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Manabu Tateno 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. An air control valve having an injection space communicating with a combustion chamber of an internal combustion engine via an automatic valve, injecting compressed air for opening the automatic valve, and a fuel control valve for metering and injecting fuel. And an air blast type fuel that is provided so as to open to the injection space, and that supplies compressed air by the air control valve after the fuel control valve is closed by performing a metered injection of the fuel by the fuel control valve. In the injection device, the air pressure in the injection space is opened during a period including a time when the fuel injection is performed by the fuel control valve except when supplying compressed air for opening the automatic valve. A fuel injection device for an internal combustion engine, comprising: means for adjusting the pressure to a predetermined value lower than the pressure and higher than the atmospheric pressure.