JP2929254B2 - Fuel supply system for lean-burn engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a lean-burn engine which is employed as an engine emission control measure.

[0002]

2. Description of the Related Art As an engine related to this kind of emission control measures, an engine disclosed in, for example, a publication "published by Power Corporation / Hiroshi Komachi / internal combustion engine" is known. As shown in FIG. 3, it comprises a main combustion chamber 2 and a sub-combustion chamber 3, and supplies gasoline to a venturi section (not shown) to supply a lean mixture B ₀ from an intake port 6 to the main combustion chamber 2. introduced, and on the other hand leave prepared rich mixture B ₁ easily ignited by pre gasoline, under pressure supplied to the auxiliary combustion chamber 3 via an on-off valve 15 and the rich mixture B ₁ in the latter half of the compression stroke of the engine In the auxiliary combustion chamber 3, the rich mixture B ₁ is ignited by the ignition plug 12, and the ignited flame is propagated to the lean mixture B ₀ in the main combustion chamber 2. According to this prior art, the main dilution by mixing with the combustion chamber 2 of the lean mixture B ₀ and rich mixture B ₁ of the auxiliary combustion chamber 3 is suppressed, easy ignition in the auxiliary combustion chamber 3 It is difficult to misfire.
Thus, HC% is low, the main combustion chamber 2 low CO% for lean _{B 0,} and, NO _X% is due to the low combustion temperature becomes lower.

[0003]

In THE INVENTION to be solved INVENTION The above prior art, since it is necessary to pressurized feed the rich mixture B ₁ of lean B ₀ different air-fuel mixture ratio in the latter half of the compression stroke of the engine,
Dark make mixture B ₁ require such means and the pressure supply device, the structure is expensive complex and manufacturing cost. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a fuel supply device which has a simple structure and can be manufactured at low cost, while clearing exhaust gas regulations.

[0004]

In order to solve the above-mentioned problems, a means adopted by the invention described in claim 1 is a fuel supply system for a lean-mixture combustion engine similar to the above-mentioned conventional example. mixture B _0, the fuel gas G from the zero governor 8 configured to supply to the venturi portion 4 through a gas regulator 9, the rich mixture B ₁ represents,
On-off valve 15 that opens only in the second half of the intake stroke of the engine
The is characterized in that the fuel gas G is configured to supply to the auxiliary combustion chamber 3 in the intake negative pressure through. In addition,
The invention as set forth in claim 2 provides the lean mixture as set forth in claim 1
In the fuel supply device of the gas combustion type engine,
City gas G as fuel gas G for Aiki B ₀
Configured to provide the over section 4, of the rich mixture B ₁
As the fuel gas G, the city gas G from the LP gas cylinder 13
The pressurized fuel gas G having a higher pressure is supplied to the gas regulator 14.
Immediately before the end of the latter half intake stroke of the engine
Characterized in that it is configured to supply
You.

[0005]

According to the first aspect of the present invention, when the fuel gas G from the zero governor 8 is supplied to the venturi section 4, the gas flow rate is adjusted to a predetermined value by the gas regulator 9 in advance, so that the venturi section 4 is provided. To mix with air A to form a required lean mixture B ₀ . This lean air-fuel mixture B ₀ is introduced from the intake port 6 into the main combustion chamber 2. On the one hand, as a rich mixture B _1, the intake fuel gas G itself
By supplying the fuel to the sub-combustion chamber 3 in the latter half of the stroke (synonymous with the latter intake stroke) , ignition is ensured. In other words, the engine
Fuel flows through the on-off valve 15 that opens only in the latter half of the intake stroke.
Fee By inhale gas G into the auxiliary combustion chamber 3 in the intake negative pressure, to suppress dilution from mixing with lean mixture B ₀ of the main combustion chamber 2 and the rich mixture B ₁ of the auxiliary combustion chamber 3 It ensures ignition. Thereby, HC%, CO%, NO
_X % will be lower. In the invention described in claim 2,
As a fuel gas G rich mixture B _1, LP gas cylinder 1
3. Pressurized fuel gas G higher than city gas from sub-combustion chamber
No need for pressurized supply device because it is configured to supply to 3
Then, immediately before the end of the latter half intake stroke of the engine,
By opening the valve only for a short time, the fuel gas G necessary for ignition is
It can be supplied to the combustion chamber 3.

[0006]

According to the first aspect of the present invention, a strong mixing
Care B _1, to open only the latter half of the intake stroke of the engine
Since the intake air is sucked into the sub-combustion chamber 3 through the on-off valve 15 by the negative pressure of the intake air, a rich mixture is supplied to the sub-combustion chamber 3
A pressurizing and supplying device is not required, and the structure is simple and can be implemented at low cost. In the invention described in claim 2,
As a fuel gas G rich mixture B _1, higher than natural gas
To supply the pressurized LP pressurized fuel gas G to the auxiliary combustion chamber 3
Then, immediately before the end of the latter half intake stroke of the engine,
By opening the valve only for a short time, the fuel gas G necessary for ignition is
Since the mixture can be supplied to the combustion chamber 3, a rich mixture is diluted.
Avoid ignition by mixing with a lean mixture to prevent dilution.
More reliable.

[0007]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a lean air-fuel mixture combustion engine according to an embodiment of the present invention, and FIG.

As shown in FIG. 1, the fuel supply device for a lean-burn engine according to this embodiment utilizes city gas G supplied at a low pressure as a fuel and employs an electronic control system. A controller 25, an igniter 26, and an ECU (fuel controller) 27 are provided. Further, the EGR (exhaust gas return pipe) 28, a part of the exhaust gas from the exhaust manifold 22 is recirculated into the venturi section 4, which by utilizing as an inert gas, so as to reduce the emission of the NO _X It is.

The governor controller 25 receives the rotation speed signal S from the rotation sensor 20 and operates the governor actuator 10 in accordance with the rotation speed of the engine. The rotation sensor 20
Is provided facing the ring gear 19 interlockingly connected to the crankshaft. The igniter 26 receives a pulse signal to Q ₁ from the pulse sensor 21 provided to face the intake pressure signal P and the ring gear 19 from the boost sensor 16 provided in the intake passage, an engine rotation signal R to the ECU27 Is output to the ignition coil 11 of the ignition plug 12 and an open / close control signal U to the electromagnetic open / close valve 29 of the EGR (exhaust gas return pipe) 28, respectively.

The ECU (fuel controller) 27 includes:
The on / off valve 15 is controlled to open and close in response to a pulse signal Q ₂ from a pulse sensor 18 provided facing the valve operating cam shaft 17 and an engine rotation signal R from the igniter 26 . The on-off valve 15 is connected to the
In conjunction with the rotation of the valve operating cam shaft 17 via the loose signal Q ₂ ,
Only the latter half of the intake stroke of the engine (the shaded area in Fig. 2)
The valve is configured to open . That is, in the present invention, the lean air-fuel mixture B ₀ is configured to supply the fuel gas G from the _zero governor 8 to the venturi section 4 via the gas regulator 9, and the rich air-fuel mixture B ₁ is supplied via the on-off valve 15. fuel gas is supplied to G, it is a fuel gas G this to supply the auxiliary combustion chamber 3 in the intake negative pressure in the second half the intake stroke is a second half of the intake stroke of the engine Te.

As described above, in the present fuel supply apparatus, the fuel gas G from the zero governor 8 is adjusted to a predetermined value by the gas regulator 9, and is mixed with the air A in the venturi section 4 to obtain a required lean mixture B _0. Becomes This lean mixture B ₀ is introduced from the intake port 6 into the main combustion chamber 2. On the other hand, the ignition is ensured by supplying the fuel gas G itself to the sub-combustion chamber 3. That is, by causing sucked fuel gas G in the auxiliary combustion chamber 3 in the intake negative pressure in the second half the intake stroke of the engine, the main combustion chamber 2 of the lean mixture B ₀ of the rich mixture B ₁ of the auxiliary combustion chamber 3 The ignition is ensured by suppressing the dilution caused by mixing. Thus, as in the conventional example _{HC%, CO%, NO X} % is low. Further, since the fuel gas G is sucked into the sub-combustion chamber 3 by the intake negative pressure in the latter half intake stroke, there is no need for a means for producing a rich air-fuel mixture or a pressurized supply device, so that the structure is simple and inexpensive. it can.

[0012] Incidentally, the rich mixture B ₁ represents supplies as indicated in phantom, the pressurized fuel gas G from the LP gas cylinder 13 to the auxiliary combustion chamber 3 in the second half the intake stroke of the engine via the gas regulator 14 It may be configured as follows. The gas discharge pressure from the LP gas cylinder 13 is higher than that of city gas, usually about ² kg / cm ^2. Therefore, when the fuel gas G is sucked into the sub-combustion chamber 3 at the intake negative pressure, the gas is discharged during the latter half of the engine intake stroke. It is only necessary to open the on-off valve 15 for a short time just before the end and supply the fuel gas G. In other words, by supplying the fuel gas G immediately before the end of the second half the intake stroke of the engine, by mixing concentrated fuel gas B ₁ is a lean fuel gas B ₀ to prevent the dilution, the ignited more reliably It is.

The present invention is not limited to the above embodiment, and the presence or absence of the EGR (exhaust gas return pipe) 28 does not matter. It is not necessary to say that the present invention can be implemented with other appropriate changes.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a lean-burn engine according to an embodiment of the present invention.

FIG. 2 shows a fuel gas G according to an embodiment of the present invention in a sub-combustion chamber 3;
6 is a time chart showing the timing of supplying the power supply to the power supply.

FIG. 3 is a sectional view of a main part of a lean-burn engine according to a conventional example.

[Explanation of symbols]

2 ... Main combustion chamber, 3 ... Sub combustion chamber,
4 Venturi section, 5 Intake port, 8 Zero governor, 9 Gas regulator, 13 L
P gas cylinder, 14 ... gas regulator 15 ... off valve, B 0 _... lean, B 1 _... rich mixture,
G: Fuel gas.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-156982 (JP, A) JP-A-5-113148 (JP, A) JP-A-4-259651 (JP, A) JP-A-58-58 180720 (JP, A) JP-A-58-18514 (JP, A) JP-A-5-58839 (JP, U) JP-A-52-152902 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 21/02 F02B 15/00 F02B 19/10

Claims (2)

(57) [Claims] 1. A lean air-fuel mixture (B ₀ ) is supplied from an intake port (6) to a main combustion chamber (2) via a venturi section (4), and a rich air-fuel mixture (B ₁ ) is supplied to a sub-combustion chamber ( 3)
And the flame ignited in the sub-combustion chamber (3) is propagated to the lean mixture (B ₀ ) in the main combustion chamber (2). The lean mixture (B ₀ ) is configured to supply the fuel gas (G) from the _zero governor (8) to the venturi section (4) via the gas regulator (9), and the rich mixture (B ₁ ) Opens only the second half of the engine intake stroke
A fuel supply system for a lean-burn engine, characterized in that the fuel gas (G) is supplied to the sub-combustion chamber (3 ) at the intake negative pressure through the on-off valve (15) . 2. A lean air-fuel mixture combustion system according to claim 1.
In the fuel supply device of the engine, the fuel gas (G) of the lean mixture (B ₀ ) is
The gas (G) is supplied to the venturi section (4), and the fuel gas (G) of the rich mixture (B ₁ ) is formed.
Te, higher than natural gas (G) from the LP gas cylinder (13)
Lean-burn type of pressure of the pressurized fuel gas (G) characterized by being configured to supply shortly before the end of the second half the intake stroke of the engine via the gas regulator (14) to the auxiliary combustion chamber (3) Engine fuel supply.