JPS6114464A - Exhaust recirculation controller for engine - Google Patents

Abstract

PURPOSE:To improve engine stability by installing an exhaust feed control means for feeding exhaust from an exhaust feeding part and a swirl generating mechanism for allowing the exhaust supplied into a cylinder to generate swirl. CONSTITUTION:An exhaust feeding part 40 for feeding a portion of exhaust into a cylinder 4 from the upper part of the cylinder 4 having a spark plug 13 arranged. An exhaust feed controlling means 51 feeds exhaust from the exhaust feeding part 40 in the latter half of suction cycle at least in case of low load. A swirl generating means 52 allows the exhaust supplied into the cylinder 4 to generate swirl. Therefore, engine stability can be improved, securing the superior emission faculty.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an exhaust velocity flow control method for controlling the exhaust gas recirculation rate when a part of the exhaust gas is recirculated to the engine in order to reduce NOx in the exhaust gas. This relates to improvements in equipment.

(Prior Art) In general, in the exhaust gas recirculation vjup system of this type of engine, a part of the exhaust gas is recirculated and supplied to the combustion chamber based on the opening operation of the intake valve during the intake stroke of each cylinder. ing. For example, in the method disclosed in Japanese Patent Application Laid-Open No. 57-143126, an exhaust recirculation passage is opened to a sub-intake passage for light duty vehicles, which has a smaller passage area than the main intake passage, and is used to reduce engine speed and load. Sometimes, when the intake valve is opened, part of the exhaust gas is supplied from the exhaust gas recirculation passage to the combustion air from the upper part of the cylinder through the light-load auxiliary intake passage.

(Problem to be solved by the invention) However, in the above conventional system, d3 during the intake stroke.
Since the recirculation of the exhaust gas is carried out in accordance with the intercropping a of the intake valve, υE air is recirculated and distributed throughout the entire combustion body, and as a result, the combustion) sound is affected by the growth of the flame kernel. Although it is possible to effectively lower the combustion temperature near the ignition plug at the top of the spark plug, where the combustion temperature is quite high, and to reduce V cumulates (NOX), there are combustion options where the combustion temperature does not become so high.
In the lower part, the exhaust gas is distributed almost unnecessarily, and the NOx reduction efficiency with respect to the amount of exhaust gas recirculation deteriorates, and this results in poor engine stability.

The present invention has been made in view of the above, and its purpose is to appropriately set the recirculation timing of exhaust gas so that the combustion temperature can be reduced only in the upper part of the combustion chamber where the ignition plug is installed. The purpose of the present invention is to unevenly distribute exhaust gas, efficiently reduce NOx with a minimum amount of exhaust gas recirculation, and improve engine stability.

(Another Means to Solve the Problem) In order to achieve the above object, the solution of the present invention includes an exhaust supply section that supplies part of the exhaust gas from the upper part of the cylinder in which the ignition plug is disposed into the cylinder. In an exhaust gas recirculation control device for an engine, there is provided an exhaust supply control means for supplying exhaust gas from the exhaust supply section in the latter half of the intake stroke at least during low load, and a means for generating a swirl in the exhaust gas supplied into the cylinder. This is provided with a swirl generation mechanism that causes the

(Function) With the above configuration, in the present invention, ()1 in the latter half of the intake stroke.
By supplying air into the combustion chamber from the upper part of the cylinder while generating a swirl, the recirculated exhaust gas is distributed with gll force only to the upper part of the combustion chamber, thereby efficiently reducing NOx.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

In Figures 1 to 3, 1 is a cylinder block 2.
and the cylinder 4 formed by the cylinder head 3
5 is a piston that reciprocates within the cylinder 4; 6 is a combustion chamber defined within the cylinder 4 by the piston 5; 7 is an intake passage that supplies intake air into the combustion chamber 6; 8 is a combustion chamber. The intake passage 7 includes, in order from upstream, a venturi 15a of the carburetor 15, a throttle valve 9 that controls the amount of intake air, and an intake passage downstream of the throttle valve 9. A surge tank 10 is provided to absorb the pulsations. In addition, 11 is an intake valve provided at the opening 7a of the intake passage 7 to the combustion chamber 6, 12 is an exhaust valve provided at the opening 8a of the combustion chamber 61\ of the exhaust passage 8, and 13 is an intake passage of the combustion chamber 6. This is an ignition plug disposed above the cylinder 4 between the frontage part 7a and the exhaust passage frontage part 8d. Further, 14 is an air cleaner provided at the upstream end of the intake passage 7.

Furthermore, as shown in enlarged detail in Fig. 2 d5 and Fig. 3,
The intake passage 7 downstream of the surge tank 10 is divided into a primary intake passage 7b and a secondary intake passage 7C by a partition wall 2o)
The primary side intake passage 7b is formed to have a smaller passage area than the secondary side intake passage 7c, and its downstream end is opened toward the circumferential direction of the cylinder 4. It is formed so as to generate an intake swirl K within the cylinder 4 while increasing the flow velocity of intake air that wets the side intake passage 7b. On the other hand, in the secondary side intake passage 7c, the 2
A swirl control valve 22 is provided that opens and closes the next intake passage 7c to control the strength of the swirl in the next intake passage 7b, and the downstream end of the second intake passage 7C is connected to the upper surface of the piston 5. When the engine 1 (E On the other hand, when the engine 1 shifts to the high-speed convex/negative region, the opening degree of the swirl control valve 22 is increased accordingly, thereby increasing the inflow ratio Ipa of intake air from the secondary intake passage 7C, and increasing the intake air flow into the cylinder. The intensity of the swirl within 4 is weakened.

And, in the middle of the exhaust passage 8, there is a contact point for purifying the exhaust gas! , 35 are arranged on the catalyst 35? Niko I
The flow end of the IJ1 air flow passage 36 for recirculating a part of the exhaust gas to the engine 1 is interposed between the JI air passage 8 and the
The downstream end of the 1st air recirculation passage 36 is opened to the primary side intake passage 7b of the intake passage 7, and the exhaust flow is connected to the fuel injection valve 2.
The arrangement is such that it collides with, merges with, and overlaps the fuel flow of the first fuel flow.

In addition, an exhaust gas recirculation valve 37 is disposed in the middle of the exhaust gas recirculation passage 36, and is driven and connected to a valve body 37a that opens and closes the air flow passage 36. Guyaflam 37b and daicephram 37b
Popular total 37c and negative pressure chamber 3 formed by compartments
7 (1 and the diaphragm 37 compressed into the negative pressure air 37d)
Spring 37e that biases b in the valve closing direction of the valve body 378
The negative pressure air 37d is communicated with a negative pressure source (not shown) via a negative pressure passage 38, and a duty valve 39 is interposed in the donkey passage 38. The duty valve 39 communicates between the upstream side and the downstream side of the duty valve 39 in the negative pressure passage 38 when activated, and communicates the upstream side (negative pressure side) of the duty valve 39 in the negative pressure passage 38 when not activated. When closed, the downstream side is opened to the atmosphere, and the pressure in the negative pressure chamber 37d is regulated according to the ratio between active and inactive states, 'TJ, or duty ratio, and each lift of the valve body 378 is adjusted. The exhaust gas supply section 40 is configured to control the exhaust gas recirculation.

Furthermore, the exhaust gas recirculation passage 36 downstream of the exhaust gas recirculation valve 37 has a rotary valve 715 that opens and closes the exhaust gas recirculation passage 36.
The rotary valve 45 is drivingly connected to the engine 1 via a variable valve timing 4M4t446 that adjusts the valve timing.

The operation of the second identity valve 39 and variable valve timing mechanism 46 is controlled by the controllers 1 to 47 only when the engine 1 is at a low or medium angle load. That is, as shown in FIG. 1, the controller 47 detects the rotation angle of the engine 1 based on the signals from the throwers 1 to 48 which detect the valve opening of the throttle valve 9 and the rotation angle of the distributor/19. Receives the crank angle εQ 'rL from the crank angle sensor 50 that detects the crank angle and rotational speed, and a3 As shown in Fig. 4, the screw top dead center (TD)
C) From the previous intake valve opening point IO to the piston bottom dead center (BD
C) Intake valve opening W up to iG intake valve closing point IC
'' based on the received crank angle signal, and controls the variable valve timing TA mechanism 46 to open the low-return valve 45 only in the latter half (preferably excluding the final period) of the intake valve opening period. . Therefore, the controllers 1 to 47 constitute an exhaust supply control means 51 or 4111 for supplying exhaust gas from the exhaust supply section 40 to at least the low load intake port in the latter half of the intake stroke. Also, a rotary valve 45.

When a part of the exhaust gas flows into the combustion chamber 6 through the primary side intake passage 7b due to the opening operation of the primary side intake passage '187,
b constitutes a swirl generation structure 52 that causes the viscosity supplied into the cylinder 4 to form a swirl.

Therefore, in the above embodiment, the engine 1 is
At medium load, the air-fuel mixture flows through the primary intake passage 7b or the secondary intake passage 7C between the intake valves 1; It flows into the combustion chamber 6 without generating swirl, and is almost uniform throughout the combustion chamber 6!
After two distributions, the next IR expansion stroke hits the ignition of the spark plug 1 of the cylinder 4 and ignites, resulting in a good combustion.

At this time, the exhaust gas t from the exhaust gas recirculation passage 36 passes through the primary intake passage 7b in the second half of the intake stroke (excluding the final stage), flows into the combustion chamber 6 while forming a swirl K, and the combustion temperature increases. It is unevenly distributed only in the vicinity of the ignition plug 13 at the upper part of the combustion chamber 6, where the temperature is higher, and this uneven distribution tit is strongly maintained by the swirl K described above. As a result, the combustion of the air-fuel mixture in the explosion-expansion stroke is performed while the combustion temperature is effectively suppressed in the upper part of the combustion chamber 6, and the generation of NOx is effectively reduced.

In addition, since NOx is effectively reduced by the minimum amount of recirculated exhaust gas that is unevenly distributed only in the upper part of the combustion chamber 6 where the combustion temperature is considerably high, NOx light 1
It is possible to efficiently reduce the amount of damage caused by the engine, and improve engine stability. Note that the exhaust gas recirculated to the combustion chamber 6 is based on the exhaust gas recirculation except at the end of the intake stroke, and the i of the ignition plug 13 is
Since there are no separate plants in the vicinity, a sufficient amount of air-fuel mixture can be ensured.

In the above embodiment, the carburetor 15 is used as the fuel supply device d. Although the present invention has been described for the case where it is applied to an engine, the present invention can be similarly applied to an engine equipped with a fuel injection device that injects fuel to each cylinder at the same port. Of course you can.

(If the invention is applied to the engine viscous flow control device of the present invention, the combustion temperature will be considerably high, at least at low load.) By recirculating and distributing the exhaust gas, the combustion humidity of the air-fuel mixture can be effectively lowered with the minimum required flow rate, and the generation of NOx can be efficiently reduced, which improves engine stability while ensuring good emission performance. It is possible to improve this.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a general schematic diagram, FIG. 2 is a vertical cross-sectional view of main parts of the engine, FIG. 3 is a bottom view of the cylinder head, and FIG. The figure is a TJ explanatory diagram showing the exhaust gas recirculation timing that corresponds to the intake stroke. 4... Cylinder, 13... Ignition plug, 40... Cultivation supply section, 51... Exhaust supply control means, 52... Swirl generation means.

Claims (1)

[Claims] (1) In an exhaust gas recirculation control system for an engine that is provided with an exhaust gas supply section that supplies part of the exhaust gas from the upper part of the cylinder where the ignition plug is disposed into the cylinder, the exhaust gas supply section is installed in the second half of the intake stroke at least when the load is low. 1. An exhaust gas recirculation control device for an engine, comprising: an exhaust supply control means for supplying exhaust gas from the cylinder; and a swirl generation mechanism for generating a swirl in the exhaust gas supplied into the cylinder.