JPH06173823A - Assist air type fuel injection device - Google Patents

Abstract

(57) [Summary] [Purpose] When the fuel is distributed from the single fuel injector to the sub-combustion chamber and the main combustion chamber together with the supercharging assist air, the air-fuel ratio A / F in the sub-combustion chamber is adjusted appropriately. Within a certain range, the mixture is ignited with high responsiveness by the spark plug in the auxiliary combustion chamber. [Structure] The fuel injected into the premix chamber 14 is atomized by supercharging assist air from the air injector 4,
The check valves 15 and 18 are opened by the pressure of the premixing chamber 14, and the fuel is distributed from the inside of the premixing chamber 14 to the main combustion chamber A1 and the auxiliary combustion chamber A2 via the small diameter nozzle portion 11B of the nozzle cylinder 11. Supply. Then, the spring bearing 20 of the check valve 18 is seated on the stopper cylinder 21 against the valve spring 19 to prevent the fuel in the premixing chamber 14 from being excessively supplied to the auxiliary combustion chamber A2, and to prevent the auxiliary combustion. Spark plug 24 in chamber A2
Produces a rich mixture that can be ignited with certainty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assist air type fuel injection device adapted to inject fuel into a combustion chamber of an automobile engine together with supercharged assist air, and more particularly to a direct cylinder fuel injection type fuel injector. Relates to an assist air type fuel injection device.

[0002]

2. Description of the Related Art Generally, an assist air type fuel injection system equipped with a direct injection type fuel injector mounted in an automobile engine or the like is provided on a cylinder head side of an engine body and is provided in a combustion chamber of the engine body. Direct injection type fuel injector for injecting fuel from the injection nozzle, and supercharging assist air is supplied to the air chamber formed around the injection nozzle of the fuel injector to atomize the fuel injected from the injection nozzle. To change the supercharging assist air supply means, a fuel pipe for supplying the fuel discharged from the fuel pump into the fuel injector, and a fuel pressure (fuel pressure) in the fuel pipe based on the control pressure from the intake pipe. And a pressure regulator.

In this type of prior art assist air type fuel injection device, when the fuel is injected from the in-cylinder direct injection type fuel injector into the combustion chamber during the intake stroke of the engine, the supercharged assist air supply means is used for injection. Supercharging assist air is supplied into the air chamber around the nozzle to promote atomization of the injected fuel. Then, by spraying this atomized fuel from the fuel injector into the combustion chamber of the engine body, the mixing efficiency of the fuel and the intake air in the combustion chamber is enhanced to improve the combustion efficiency of the fuel and clean the exhaust gas. And the improvement of fuel efficiency.

[0004]

In the prior art described above, the fuel injected from the injection nozzle of the fuel injector is atomized by the supercharging assist air, but this atomized fuel is introduced into the combustion chamber of the engine body. When jetted and mixed with intake air from the intake manifold, the concentration of the air-fuel mixture may become non-uniform in the combustion chamber, and the air-fuel mixture is lean around the spark plug.
When it becomes, the ignitability of the air-fuel mixture will decrease. In particular, during lean burn control using a lean air-fuel ratio having an air-fuel ratio A / F of about 18 to 25, the ignitability of the air-fuel mixture is significantly reduced, making it difficult to effectively combust the air-fuel mixture in the combustion chamber.

Further, in order to improve the ignitability by the ignition plug even in a lean mixture during lean burn control, the cylinder head of the engine body communicates with the combustion chamber, and the secondary combustion has a volume smaller than that of the combustion chamber. A chamber is formed, and a lean air-fuel mixture of fuel and intake air from the main injector is sucked into the combustion chamber from the intake port of the cylinder head, and a sub-combustion chamber is provided with an in-cylinder direct injection sub-injector and an ignition plug. Other conventional techniques for mounting the same are also known. In addition, in other conventional techniques, by injecting fuel from the sub-injector into the sub-combustion chamber, the air-fuel mixture in the sub-combustion chamber has a rich tendency (rich), and the ignitability by the spark plug is improved. .

However, in this case, since it is necessary to provide the main injector on the intake port side of the cylinder head and the sub-injector in the auxiliary combustion chamber, the injection amount of fuel injected from each injector is controlled by a control device or the like. Since it is necessary to individually calculate and control, the control process becomes complicated, and it is necessary to provide two fuel injectors, the number of components of the entire fuel injection device increases, and the workability at the time of assembling becomes poor. There is a problem of becoming.

Therefore, the present applicant has previously filed Japanese Patent Application No. 4-11.
No. 4142 (hereinafter referred to as prior art), a partition member is provided between the cylinder head of the engine body and the fuel injector, and the partition member serves to divide the combustion chamber into a main combustion chamber on the cylinder side and a sub combustion chamber on the fuel injector side. The partition wall member is provided with a distribution nozzle for distributing the fuel ejected together with the supercharging assist air from the fuel injector to the main combustion chamber and the sub combustion chamber, and the distribution nozzle divides the sub combustion chamber. The assist air type fuel injection device has been proposed in which the supercharged assist air and the fuel that are distributed and ejected into the main combustion chamber are ignited by a spark plug in the sub combustion chamber and the flame at this time is ejected into the main combustion chamber.

In this prior art, the fuel ejected from the fuel injector together with the supercharging assist air is distributed and supplied to the main combustion chamber side and the sub combustion chamber side by the distribution nozzle provided in the partition wall member. A rich mixture is produced in the sub-combustion chamber, a lean mixture is produced in the main combustion chamber, and the rich mixture in the sub-combustion chamber is ignited by a spark plug to generate a flame at this time. There is an advantage that the lean air-fuel mixture in the main combustion chamber can be surely combusted by being ejected into the main combustion chamber, and lean burn control and the like can be stably performed using a single fuel injector.

However, in this prior art, the air-fuel ratio A / F in the auxiliary combustion chamber cannot be controlled within a proper range over the entire engine speed range, and the air-fuel mixture is ignited in the auxiliary combustion chamber. There is an unsolved problem that it is difficult to instantly ignite with high responsiveness.

That is, in the auxiliary combustion chamber, as shown in FIG.
When the air-fuel ratio A / F is in the range of the proper value 8 to 12, the air-fuel mixture can be instantly ignited by minimizing the ignition time of the air-fuel mixture, but the air-fuel ratio A / F is proper. If the concentration exceeds the range of values and becomes richer or leaner, the ignitability of the air-fuel mixture becomes significantly worse. However, since the injection amount of fuel injected from the fuel injector is determined based on the intake air amount, if the intake air amount increases, for example, during acceleration of the engine, the injection amount of fuel injected from the fuel injector at this time will increase. As a result, the excess fuel is supplied to the auxiliary combustion chamber and the air-fuel ratio A / F cannot be suppressed within an appropriate range.

Further, in the above-mentioned prior art, since the flame ejected from the auxiliary combustion chamber toward the main combustion chamber has a solid columnar shape or a conical shape, contact between this flame and the lean air-fuel mixture in the main combustion chamber. There is an unsolved problem that the area cannot be made sufficiently large and it is difficult to sufficiently improve the combustion efficiency of the air-fuel mixture in the main combustion chamber.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention is applied when fuel is distributed from a single fuel injector to the auxiliary combustion chamber and the main combustion chamber together with supercharging assist air. , The air-fuel ratio A / F in the sub-combustion chamber can be suppressed within an appropriate range, and the air-fuel mixture in the sub-combustion chamber can be ignited with high responsiveness by the spark plug, and from the sub-combustion chamber to the main combustion chamber. An object of the present invention is to provide an assist air type fuel injection device capable of increasing the contact area between the ejected flame and the air-fuel mixture in the main combustion chamber, and reliably improving the overall combustion efficiency.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is provided with an in-cylinder direct injection type fuel injector, and atomizes the fuel injected from the fuel injector by supercharging assist air, In an assist air type fuel injection device for supplying into a combustion chamber of a main body, a premix chamber for the fuel and supercharge assist air is provided between a cylinder head of the engine main body and a fuel injector and is provided on the fuel injector side. A partition wall that defines a main combustion chamber and a sub combustion chamber on the combustion chamber side of the engine body, and is formed on the partition wall.
A distribution passage for distributing the fuel, which is injected from the fuel injector into the premix chamber and atomized by the supercharging assist air, to the main combustion chamber side and the sub combustion chamber side, and the distribution passage on the main combustion chamber side. A first check valve provided in the passage for allowing the fuel to flow from the premixing chamber toward the main combustion chamber and blocking the flow in the opposite direction; and a passage on the auxiliary combustion chamber side of the distribution passage. And a second check valve that allows the fuel to flow from the premix chamber toward the sub-combustion chamber and blocks the reverse flow, the second check valve including the second check valve. A stopper is provided to close the passage on the side of the sub-combustion chamber when the pressure in the chamber exceeds a predetermined pressure, and the fuel distributed and supplied to the sub-combustion chamber via a second check valve is supplied to the sub-combustion chamber. I tried to ignite with a spark plug It adopts a configuration comprising a feature and.

Further, the partition wall is formed with an annular communication hole for communicating the auxiliary combustion chamber with the main combustion chamber, and the flame of fuel ignited by an ignition plug in the auxiliary combustion chamber is main-combusted from the communication hole. It is preferable to have a configuration in which it is ejected in a hollow shape toward the room.

[0015]

With the above structure, when the injection amount of the fuel injected from the fuel injector is increased due to the increase of the intake air amount during acceleration of the engine, the pressure in the premix chamber exceeds the predetermined pressure. Therefore, the stopper of the second check valve closes the passage on the sub-combustion chamber side of the distribution passage to block the supply of excess fuel into the sub-combustion chamber, and the air-fuel ratio A / It is possible to prevent the F from becoming excessively rich.

Further, if the partition wall is formed with an annular communication hole for communicating the auxiliary combustion chamber with the main combustion chamber, the flame generated by igniting the air-fuel mixture in the auxiliary combustion chamber is cylindrical from the communication hole of the partition wall. Alternatively, the air-fuel mixture can be ejected into the main combustion chamber in the shape of a hollow cone and contact the lean air-fuel mixture in a large area with a large area to reliably burn the air-fuel mixture in the main combustion chamber.

[0017]

Embodiments of the present invention will be described below with reference to FIGS.

In the figure, 1 is an engine body, 2 is a cylinder head which constitutes a part of the engine body 1,
The cylinder head 2 forms a combustion chamber A in the cylinder with a piston (neither is shown), and the cylinder head 2 communicates with the inside and outside of the combustion chamber A as shown in FIG. A screw hole 2A for a mounting cylinder 8 described below is provided.

Reference numeral 3 denotes an in-cylinder direct injection type fuel injector attached to the cylinder head 2 through a partition wall body 7 described later. The fuel injector 3 is provided on the injector body 3A and on the tip side of the injector body 3A. The injection nozzle 3B is provided and a connection port 3C provided on the rear end side of the injector main body 3A is roughly configured. The injector main body 3A has an electromagnetic actuator (not shown) for driving a valve body built therein. Here, a fuel pipe (not shown) is connected to the connection port 3C of the fuel injector 3, and fuel from the fuel pump is supplied in a state where the pressure is regulated by a pressure regulator (neither is shown).
When an injection pulse is applied from the outside, the fuel injector 3 opens and closes the valve element by an electromagnetic actuator to inject fuel from the tip of the injection nozzle 3B into the premix chamber 14 described later.

Reference numeral 4 denotes an air injector attached to the cylinder head 2 via a partition wall body 7. The air injector 4 is provided with an injector body 4A, an injection nozzle 4B and a connection port 4C, which is substantially the same as the fuel injector 3. The main body 4A has a built-in electromagnetic actuator (neither is shown) that drives the valve body. Here, an air pipe (not shown) is connected to the connection port 4C of the air injector 4, and compressed air (supercharging assist air) from the air pump is regulated by a relief valve (neither is shown) or the like. Supplied in condition. When a pulse is applied to the air injector 4 from the outside in the same manner as the fuel injector 3, the valve body is opened and closed by an electromagnetic actuator to open the premix chamber 1 from the tip of the injection nozzle 3B.
The supercharging assist air is jetted toward the inside of 4.

Reference numeral 5 denotes a stopper plate for positioning the fuel injector 3 and the air injector 4 with respect to the partition wall body 7. The stopper plate 5 has its left and right ends extending toward the fuel injector 3 and the air injector 4, respectively. The injector bodies 3A and 4A are hooked as shown in FIG. In addition, the stopper plate 5
The fixing bolt 6 is inserted through the central portion of the
The front end side of is attached to the holder 10 of the partition wall body 7 described later. Then, the fixing bolt 6 is connected to the fuel injector 3 and the air injector 4 via the stopper plate 5.
And are fixed to the holder 10.

Reference numeral 7 denotes a partition wall body provided between the cylinder head 2, the fuel injector 3 and the air injector 4. The partition wall body 7 is formed in a stepped cylindrical shape as shown in FIG. A mounting cylinder 8 in which a small-diameter cylindrical portion 8A is screwed into a screw hole 2A of the cylinder head 2, and a nozzle cylinder 11 and a mixing head 13 which will be described later and are arranged in the mounting cylinder 8.
And a holder 10 disposed on the nozzle cylinder 11 and the mixing head 13 and fixed to the mounting cylinder 8 by screwing the end cover 9 onto the mounting cylinder 8. A pair of introduction passages 10A (only one of which is shown) for guiding the fuel from the fuel injector 3 and the supercharging assist air from the air injector 4 into the premixing chamber 14 at a predetermined inclination angle is formed therein.

Reference numeral 11 denotes a nozzle cylinder arranged coaxially in the mounting cylinder 8, and the nozzle cylinder 11 has a bottomed cylinder portion 11A on the upper end side.
Is fitted and fixed on the annular step portion 8B of the mounting cylinder 8, and a small diameter nozzle portion 11B projecting downward is integrally formed at the center of the bottom portion of the bottomed tubular portion 11A. And the nozzle cylinder 1
The first small-diameter nozzle portion 11B extends to the tip side of the small-diameter tubular portion 8A of the mounting cylinder 8 and forms an annular communication hole 12 with the tip side of the small-diameter tubular portion 8A. The combustion chamber A of the engine body 1 is divided into a main combustion chamber A1 and a sub-combustion chamber A2 between the mounting cylinder 8 and the nozzle cylinder 11 by a partition wall body 7.
2 communicates with the main combustion chamber A1 through an annular communication hole 12.

As shown in FIG. 3, the bottomed cylindrical portion 11A of the nozzle cylinder 11 is provided with a stepped hole 11C located outside the small-diameter nozzle portion 11B in the radial direction to communicate the premixing chamber 14 with the auxiliary combustion chamber A2. Is formed, and the periphery of the lower end side of the stepped hole 11C is a valve seat 11D for the check valve 18 described later. The stepped hole 11C of the nozzle cylinder 11 is the small diameter nozzle portion 11
B and distribution holes 13B and 13C which will be described later constitute a distribution passage, and a passage on the side of the auxiliary combustion chamber A2 of the distribution passage is constituted by a stepped hole 11C and a distribution hole 13C.

Reference numeral 13 denotes a mixing head arranged between the bottomed cylinder portion 11A of the nozzle cylinder 11 and the holder 10.
The mixing head 13 has an eccentric hole 13A as shown in FIG.
Is formed as a bottomed cylindrical body having a premix chamber 14 between the eccentric hole 13A and the holder 10. And
The premix chamber 14 mixes the fuel from the fuel injector 3 and the supercharging assist air from the air injector 4 guided through each introducing passage 10A of the holder 10 in a swirling flow state, and the supercharging assist air causes the fuel to flow. Promote the atomization of.

Distribution holes 13B and 13C are formed on the bottom side of the mixing head 13 for communicating the premixing chamber 14 with the main combustion chamber A1 and the auxiliary combustion chamber A2.
B and 13C form a part of the distribution passage. The distribution hole 13B constitutes a main combustion chamber A1 side passage of the distribution passage together with the small diameter nozzle portion 11B of the nozzle cylinder 11, and the periphery of the lower end side of the distribution hole 13B formed as a stepped hole is a check valve described later. It is a valve seat 13D for 15.

Reference numeral 15 is a distribution hole 13 of the mixing head 13.
A first check valve provided in B is shown. The check valve 15 has a valve spring 16 in a normally closed direction so that a poppet-shaped valve portion 15A is seated on a valve seat 13D.
7, the combustion pressure from the main combustion chamber A1 is prevented from flowing back to the premixing chamber 14 via the small diameter nozzle portion 11B. When the fuel and the supercharging assist air are supplied into the premix chamber 14, the check valve 15 is opened by the pressure at this time as shown in FIGS. Valve seat 1
It is distributed from the 3D side through the small diameter nozzle portion 11B into the main combustion chamber A1 and ejected. Further, the spring bearing 17 has a plurality of communication grooves 17 for communicating the inside of the premixing chamber 14 with the valve seat 13D side.
A, 17A, ... Are formed in the radial direction.

Reference numeral 18 denotes a distribution hole 13 of the mixing head 13.
A second check valve provided in C is shown. The check valve 18 is a stopper in the direction always closed by a valve spring 19 so that the poppet type valve portion 18A is seated on and seated on the valve seat 11D of the nozzle cylinder 11. It prevents the combustion pressure from the main combustion chamber A1 and the auxiliary combustion chamber A2 from flowing back to the premixing chamber 14 through the stepped hole 11C of the nozzle cylinder 11 by being urged through the spring receiver 20 as ing. And the check valve 18
When fuel and supercharging assist air are supplied into the premix chamber 14, the pressure at this time opens the valve as shown in FIG.
The remaining air-fuel mixture of this fuel and supercharging assist air is used as the valve seat 1
It is distributed from the 1D side into the auxiliary combustion chamber A2 and ejected.

Reference numeral 21 denotes a stopper cylinder which is located around the valve spring 19 and is fitted and fixed to the upper side of the stepped hole 11C and the lower side of the distribution hole 13C. It is formed as a valve seat 21A for the receiver 20, and when the pressure in the premix chamber 14 exceeds a predetermined pressure (actually,
When a small amount of time has elapsed since the fuel was injected from the fuel injector 3 into the premix chamber 14), the spring bearing 20
5 is seated against the valve spring 19 as shown in FIG. 5, and the spring receiver 20 closes the stepped hole 11C of the nozzle cylinder 11. As a result, the fuel in the premixing chamber 14 is stored in the auxiliary combustion chamber A2
The air-fuel ratio A / F in the auxiliary combustion chamber A2 exceeds the proper value range 8 to 12 illustrated in FIG. 7 and becomes richer in any engine operating condition. It is designed to prevent

Here, the valve spring 19 is set to a predetermined spring load, and when fuel is injected from the fuel injector 3 into the premixing chamber 14, the pressure at this time causes the check valve 18 to move as shown in FIG. When the pressure in the premixing chamber 14 exceeds the set pressure of the valve spring 19 after a certain minute time has elapsed after the fuel injection, the check valve 18 is shown in FIG. The valve is closed like this. In this case, the check valve 15 on the main combustion chamber A1 side repeatedly opens and closes as shown by a characteristic line 22 shown in FIG. 6 according to the operating state of the engine, but the check valve 18 on the auxiliary combustion chamber A2 side has a characteristic line 23. As described above, the valve is repeatedly opened and closed repeatedly with a substantially constant minute time.

The auxiliary combustion chamber A2 is formed with a smaller volume than the main combustion chamber A1, and even when a relatively small amount of fuel is injected from the premixing chamber 14 through the check valve 18, the auxiliary combustion chamber A2. A rich air-fuel mixture having an air-fuel ratio A / F within the proper value range of 8 to 12 illustrated in FIG. 7 is generated therein so that the spark from the spark plug 24 described later can be surely ignited. On the other hand, in the main combustion chamber A1 having a large volume, the nozzle cylinder 11 is stepped so that the fuel is distributed so as to generate a lean air-fuel mixture suitable for performing lean combustion by mixing with intake air. The hole 11C distributes a part of the fuel ejected together with the supercharging assist air from the premix chamber 14 to the side of the auxiliary combustion chamber A2, and the remaining fuel is supplied to the small-diameter nozzle portion 11
B is discharged into the main combustion chamber A1 together with the supercharging assist air. Then, a leaner mixture than usual is produced in the auxiliary combustion chamber A2 and the main combustion chamber A1 so that lean burn control can be performed.

Further, reference numeral 24 denotes an ignition plug attached to the mounting cylinder 8 so as to face the inside of the auxiliary combustion chamber A2. The ignition plug 24 ignites the air-fuel mixture in the auxiliary combustion chamber A2 and The flame produced by the combustion is ejected from the annular communication hole 12 toward the main combustion chamber A1.

The assist air type fuel injection device according to this embodiment has the above-mentioned structure, and its operation will be described below.

First, the fuel injector 3 is supplied with the fuel whose fuel pressure is adjusted by the pressure regulator according to the operating state of the engine from the connection port 3C side, and the air injector 4 is supplied with the supercharging assist air from the air pump 4C. Supplied from the side. Then, when an electric signal (injection pulse or the like) is applied to each of the fuel injector 3 and the air injector 4 from a control unit (not shown) as a control device, the respective valve bodies of the fuel injector 3 and the air injector 4 open. From the injection nozzles 3B and 4B to the premixing chamber 14 of the partition 7
Fuel and supercharge assist air are injected inward.

The fuel injected into the premix chamber 14 is atomized by the supercharging assist air, and the check valves 15 and 18 are opened by the pressure at this time to open the nozzles from the premix chamber 14. A small diameter nozzle portion 11B of the cylinder 11,
It is distributed and supplied to the main combustion chamber A1 and the auxiliary combustion chamber A2 through the stepped hole 11C. At this time, the check valve 15 is repeatedly opened and closed as indicated by the characteristic line 22 shown in FIG. 6 substantially corresponding to the opening and closing of the fuel injector 3, and the main combustion chamber A1
A relatively lean mixture is created inside. Further, the check valve 18 is repeatedly opened and closed at a substantially constant time as shown by the characteristic line 23 shown in FIG. 6 to generate a rich air-fuel mixture in the auxiliary combustion chamber A2 to the extent that the ignition plug 24 can reliably ignite it. .

The ignition plug 24 ignites the air-fuel mixture in the auxiliary combustion chamber A2 and directs the flame generated by the combustion of the air-fuel mixture from the annular communication hole 12 to the main combustion chamber A1. By ejecting in a shape,
The flame at this time is brought into contact with the air-fuel mixture in the main combustion chamber A1 with a relatively large contact area, and the air-fuel mixture in the main combustion chamber A1 can be stably burned even during lean burn control.

Thus, according to this embodiment, the check valve 18 on the side of the auxiliary combustion chamber A2 is provided with the stopper cylinder 21, and the upper end surface of the stopper cylinder 21 is formed as the valve seat 21A for the spring receiver 20. 3 to premix chamber 14
When fuel is injected into the inside, the check valve 18 is opened as shown in FIG. 4, and when the pressure in the premix chamber 14 rises above a predetermined pressure after a lapse of a certain minute time, the check valve 18 The spring bearing 20 is seated on the valve seat 21A of the stopper cylinder 21 against the valve spring 19 as shown in FIG. 5, and the stepped hole 11C of the nozzle barrel 11 is closed by the spring bearing 20. As shown by the characteristic line 23 shown in FIG. 6, the valve 18 is opened and closed at an almost constant minute time to prevent the fuel in the premixing chamber 14 from being excessively supplied to the secondary combustion chamber A2. Air-fuel ratio A in chamber A2
/ F can be prevented from becoming richer than the proper value range 8 to 12 illustrated in FIG. 7, and at the same time, the rich-fuel mixture suitable for ignition by the spark plug 24 in the auxiliary combustion chamber A2. Can be generated.

The small diameter nozzle portion 11B of the nozzle cylinder 11
Since the auxiliary combustion chamber A2 is formed in a tubular shape and extends in the axial direction toward the main combustion chamber A1 from the premixing chamber 14 side to the position of the communication hole 12 of the mounting cylinder 8, the auxiliary combustion chamber A2 inside the auxiliary combustion chamber A2 The flame generated by the ignition of the air-fuel mixture by the ignition plug 24 becomes a hollow cylindrical or hollow conical shape from the annular communication hole 12 and is ejected into the main combustion chamber A1. The air-fuel mixture in the combustion chamber A1 can be brought into contact with a wide range, and the air-fuel mixture can be efficiently burned to improve the combustion efficiency.

Further, when the air-fuel mixture burns in the auxiliary combustion chamber A2, the small-diameter nozzle portion 11B of the nozzle cylinder 11 is heated by the heat from the auxiliary combustion chamber A2.
The fuel ejected from the nozzle cylinder 11 into the main combustion chamber A1 through the small-diameter nozzle portion 11B is not only atomized by the supercharging assist air, but also the heat at this time promotes further vaporization, and the main combustion chamber A1 Even if a lean air-fuel mixture is generated inside, this air-fuel mixture can be surely lean-burned, and lean burn control and the like can be effectively performed.

Therefore, in this embodiment, the atomization of the fuel is promoted by the supercharging assist air, and this fuel is distributed to the sub-combustion chamber A2 and the main combustion chamber A1. A large amount of fuel can be supplied together with the supercharging assist air to generate a rich air-fuel mixture within the range of the required air-fuel ratio, and the air-fuel mixture in the auxiliary combustion chamber A2 can be reliably generated by the spark from the spark plug 24. In addition, the flame from the auxiliary combustion chamber A2 is blown into the main combustion chamber A1 in a hollow shape, so that the lean-fuel mixture in the main combustion chamber A1 can be surely burned. , For example, the engine body 1 provides a stable rotation output even during lean burn control.
And various effects such as purification of exhaust gas and improvement of fuel consumption can be achieved.

In the above embodiment, the valve spring 19 is set to have a predetermined spring load, and when fuel is injected from the fuel injector 3 into the premixing chamber 14, the pressure at this time causes the check valve 18 to operate. As shown in FIG. 4, when the pressure in the premix chamber 14 exceeds the set pressure of the valve spring 19 after allowing a certain minute time after fuel injection, the check valve 18 is spring-loaded 20. However, the present invention is not limited to this, and the fuel injection pressure from the fuel injector 3 is not limited to this.
For example, when it is within the range of about 2.55 to 3.05 Kg / cm ² , the check valve 18 is allowed to open as shown in FIG. 4, and when the fuel injection pressure further increases during engine acceleration, The spring load of the valve spring 19 may be set to a predetermined pressure so that the check valve 18 is closed by the spring receiver 20 as shown in FIG.

Further, in the above embodiment, the cylinder head 2
Although the partition body 7 is provided so as to protrude from the cylinder head 2 to the outside, the present invention is not limited to this, and for example, without attaching the mounting cylinder 8 of the partition body 7 or the like to the outside of the cylinder head 2, You may make it provide integrally.

Further, in the above embodiment, the fuel injector 3 and the air injector 4 are fixed to the holder 10 of the partition wall body 7 by the fixing bolts 6 via the stopper plate 5, but the present invention is not limited to this. Not limited to this, for example, only the fuel injector 3 is provided in the holder 10, the fuel from the fuel injector 3 is injected into the premix chamber 14, and the premix chamber 14 is supercharged from the outside via an air conduit or the like. Assist air may be introduced and the supercharged assist air may be used to atomize the fuel in the premix chamber 14.

[0044]

As described in detail above, according to the present invention, a premixing chamber for fuel and supercharging assist air is formed between the cylinder head of the engine body and the fuel injector and located on the fuel injector side. A partition wall that defines a main combustion chamber and a sub-combustion chamber is provided on the combustion chamber side of the engine body, and fuel that is atomized by supercharging assist air in the premixing chamber is provided in the partition body. And a sub-combustion chamber for forming a distribution passage, and a second check valve provided in a passage on the sub-combustion chamber side of the distribution passage is provided with a second check valve when the pressure in the premix chamber exceeds a predetermined pressure. Since a stopper that closes the passage on the side of the sub-combustion chamber is provided and the fuel distributed and supplied through the second check valve into the sub-combustion chamber is ignited by an ignition plug in the sub-combustion chamber, From fuel injector When the fuel is injected into the mixing chamber and the pressure in the premixing chamber exceeds a predetermined pressure, the stopper of the second check valve closes the passage of the distribution passage on the side of the sub combustion chamber, so that the excessive amount of pressure in the sub combustion chamber. The supply of fuel can be interrupted, the air-fuel ratio A / F in the auxiliary combustion chamber can be suppressed within an appropriate range, and the air-fuel mixture in the auxiliary combustion chamber can be ignited with high responsiveness by the spark plug. .

If the partition wall is formed with an annular communication hole for communicating the auxiliary combustion chamber with the main combustion chamber, the flame generated by igniting the air-fuel mixture in the auxiliary combustion chamber is cylindrical from the communication hole of the partition wall. Alternatively, the contact area between the flame ejected from the auxiliary combustion chamber to the main combustion chamber and the lean mixture in the main combustion chamber can be increased by making it into a hollow conical shape and ejecting into the main combustion chamber, thus reliably improving overall combustion efficiency. Various effects such as being possible can be achieved.

[Brief description of drawings]

FIG. 1 is an external view showing an assist air type fuel injection device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged view of a main part in FIG. 2, showing a state in which each check valve is closed.

FIG. 4 is an enlarged view of a main part in FIG. 2, showing a state in which each check valve is open.

FIG. 5 is an enlarged view of a main part in FIG. 2, showing a state in which a check valve on the auxiliary combustion chamber side is closed.

FIG. 6 is a characteristic diagram showing opening and closing characteristics of each check valve.

FIG. 7 is a characteristic diagram showing a relationship between air-fuel ratio and ignition time.

[Explanation of symbols]

 1 Engine Body 2 Cylinder Head 3 Fuel Injector 4 Air Injector 7 Partition Body 8 Mounting Tube 9 End Cover 10 Holder 11 Nozzle Tube 11B Small Diameter Nozzle 12 Communication Hole 13 Mixing Head 13B, 13C Distribution Hole (Distribution Passage) 14 Premixing Chamber 15 , 18 Check valve 20 Spring bearing (stopper) 21 Stopper tube 24 Spark plug A Combustion chamber A1 Main combustion chamber A2 Sub combustion chamber

Claims (2)

[Claims] 1. An assist air type fuel injection device, comprising a direct-injection fuel injector, wherein fuel injected from the fuel injector is atomized by supercharging assist air and is supplied into a combustion chamber of an engine body. It is provided between the cylinder head of the engine body and the fuel injector, defines a premixing chamber of the fuel and supercharging assist air on the fuel injector side, and a main combustion chamber on the combustion chamber side of the engine body. A partition wall defining a sub-combustion chamber, and the fuel formed in the partition wall and injected into the premixing chamber from the fuel injector and atomized by supercharging assist air to the main combustion chamber side and the sub-combustion chamber side. And a distribution passage for distributing to the main combustion chamber, the distribution passage being provided in a passage on the main combustion chamber side of the distribution passage. A first check valve that allows the fuel to flow through and prevent a reverse flow, and is provided in a passage on the side of the sub-combustion chamber of the distribution passage, and from the premix chamber toward the sub-combustion chamber. A second check valve that allows the fuel to flow and blocks a reverse flow, the second check valve including the second combustion check valve when the pressure in the premix chamber exceeds a predetermined pressure. The assist is characterized in that a stopper is provided to close the passage on the chamber side, and the fuel distributed and supplied into the auxiliary combustion chamber through the second check valve is ignited by an ignition plug in the auxiliary combustion chamber. Air fuel injection device. 2. The partition wall is formed with an annular communication hole that communicates the auxiliary combustion chamber with the main combustion chamber, and the flame of fuel ignited by an ignition plug in the auxiliary combustion chamber is main-combusted from the communication hole. The assist air type fuel injection device according to claim 1, wherein the assist air type fuel injection device is configured to be ejected in a hollow shape toward the room.