KR0167381B1 - Spark-ignition internal combustion engine - Google Patents

Abstract

We plan stability improvement at the time of lean air fuel ratio driving of spark ignition type internal combustion engine.

In a spark ignition type internal combustion engine that diminishes the air-fuel ratio according to the operating conditions, an intake machine is set such that the longitudinal vortex ratio of in-cylinder intake flow is 1.6 to 3.1 and the horizontal vortex ratio is 1.8 to 3.5 during lean air-fuel ratio operation. In addition, as a means for realizing such a longitudinal vortex horizontal vortex ratio, the intake pipe 7 is equalized and symmetrical between the cylinders, and an air control valve 11 having an opening 13 at a predetermined position is provided. The upper part of this air control valve 11 is inclined to the downstream side by a predetermined angle, and the intake port 6 is formed in the shape of the longitudinal vortex reinforcement port which causes a bell in the cylinder. The air control valve opening part 13 It is proposed to include two intake valves 14 and 15 which are variable drive with phase difference so that the intake valve 15 on the side of the door is opened early.

Description

Spark-ignition internal combustion engine

1 is a schematic plan sectional view of one embodiment of a spark ignition type internal combustion engine according to the present invention;

2 is a schematic longitudinal sectional view of the embodiment.

3 is a schematic plan view for showing the configuration of the intake manifold of the embodiment.

4 is a graph showing the relationship between the dimensions of the intake pipe and the stable combustion limit.

5 is a graph showing the relationship between the longitudinal vortex ratio and the horizontal vortex ratio of the intake air and the stable combustion limit.

6 is a graph showing the relationship between the longitudinal vortex ratio component of the intake air and the cycle variation of the average flow rate.

7 is a graph showing the relationship between cycle variation in average intake air velocity and stable combustion limit.

8 is an explanatory diagram showing the relationship between the opening configuration of the air control valve and the longitudinal vortex ratio horizontal vortex region;

9 is an explanatory diagram showing the optimum longitudinal vortex ratio and the horizontal vortex ratio region in relation to the stable combustion limit.

10 is an explanatory diagram showing the relationship between the center angle of the opening of the air control valve and the stable combustion limit.

11 is an explanatory diagram of the combustion improvement effect based on the inclination angle setting of the air control valve.

12 is a graph showing the relationship between the inclination angle of the air control valve and the cycle variation of the average flow rate of the intake air.

13 is a graph showing the relationship between the inclination angle of the air control valve and the stable combustion limit for each inclination angle.

14 is an explanatory diagram of a combustion improvement effect when the intake two valve is opened by setting a phase difference.

FIG. 15 is a graph showing the relationship between the change in phase difference of the intake two valves and the cycle variation in the average flow rate of the intake air; FIG.

FIG. 16 is an explanatory diagram showing the effect according to the embodiment of the present invention in comparison with the conventional example for each configuration requirement. FIG.

* Explanation of symbols for main parts of the drawings

1: internal combustion engine body 2: cylinder

3: cylinder head 4: combustion chamber

5: spark plug 6: intake port

7: intake manifold 8: intake collector assembly

9: intake pipe (branch) 10: passage adapter

11: air control valve 12: mounting shaft of the air control valve

13 opening of air control valve 14 first intake valve

15: second intake valve θ: inclination angle of the air control valve

β: Opening angle of air control valve

[Industrial use]

The present invention relates to an improvement of a spark ignition type internal combustion engine that diminishes air-fuel ratio according to operating conditions.

[Prior art]

In a spark-ignition internal combustion engine, air control called horizontal vortex control valves (SCVs) in which partial openings, such as cutouts, are set for the purpose of improving combustion during low load operation or lean air fuel ratio operation. It is known that the valve is fitted near the engine intake port, and the intake air flow is concentrated in the opening, thereby causing the intake air to flow in the passage and increasing the flow rate to promote the air flow in the cylinder (for example, in Japanese practice). See No. 1-91038.

[Problem to Solve Invention]

However, in such a conventional internal combustion engine, the length of the branch pipe of the intake manifold and the shape of the intake passage upstream of the air control valve generally vary from cylinder to cylinder, and there is a lack of longitudinal vortex (vertical vortex ratio) in the cylinder and air control of each cylinder. Due to the notch shape error, the valve is installed, which causes fluctuations in the average flow velocity of the intake cycle, and therefore, it is not possible to perform stable lean combustion operation or to increase the air-fuel ratio to obtain a stable operation state. There was a problem that the combustion limit was low.

The present invention aims to solve such a conventional problem.

[Means for solving the problem]

In order to achieve the above object, in the present invention, in the spark-ignition type internal combustion engine that thins the air-fuel ratio according to the operating conditions, the longitudinal vortex ratio of in-cylinder intake flow is 1.6 to 3.1 and the horizontal vortex ratio is 1.8 to lean during the lean air-fuel ratio operation. It proposes an internal combustion engine in which an intake machine of 3, 5 is set.

However, longitudinal vortex ratio = rotational speed / engine rotational speed of the longitudinal vortex in the cylinder horizontal vortex ratio = rotational speed / engine rotational speed of the horizontal vortex in the cylinder.

Moreover, this invention proposes the flame-ignition type internal combustion engine which consists of the following A-E individually or combined as a structure for obtaining such a longitudinal vortex ratio and a horizontal vortex ratio.

A. A plurality of intake pipes branching from the intake collector assembly and reaching each intake port of the engine in a symmetrical shape in the same length and cylinder row direction.

B. Mounting partially fitted air control valves in the intake passage near the intake port. However, with respect to this air control valve, it is preferable to have the following configuration a or b again.

a. In the lean air-fuel ratio operation, the opening side should be set to be inclined within the range of 20 to 30 degrees with respect to the cross section perpendicular to a predetermined amount, preferably perpendicular to the central axis of the intake passage, in the closed state.

b. The opening is formed at a portion oriented above and to one side of the mounting shaft which is almost horizontal, and preferably an angle of 45 to 75 degrees upwards is formed by the mounting axis center line of the line segment connecting the center (drawing center) point of the opening to the passage center. Form within range.

C. The shape of the intake passage immediately upstream of the air control valve is approximately the same between each cylinder, and preferably the length is within the range of 1.5 to 3.5 times the diameter in the intake port.

D. Each intake port should be shaped like a bell in the cylinder, especially in a straight line with a small angle of the inlet port centerline in the horizontal plane.

E. Air control valves Provide two intake valves which are open and driven in phase so that the intake valves on the opening side of the air openings are opened prematurely.

Recommended as a specific combination of each of these means on the premise of a spark-ignition internal combustion engine that thins the air-fuel ratio according to the operating conditions, FIG. 1 shows a plurality of intake pipes branching from the intake collector assembly and reaching each intake port of the engine. Air-conditioning valves are installed in the same length and in the direction of cylinder row, and have openings partially, and in the case of lean air-fuel ratio operation, the air control valves are controlled to be inclined by a predetermined amount in the closed state near each intake port. In addition, the intake passage shape immediately upstream of the air control valve is made substantially the same between the cylinders, and each intake port is formed in the shape of the longitudinal vortex in the cylinder.

2 shows a plurality of intake pipes branching from the intake collector assembly to each intake port of the engine in a symmetrical shape in the same length and cylinder row direction, and having partial openings, in a closed state during lean air-fuel ratio operation. An air control valve controlled to incline the opening to a predetermined amount downward is inserted near each intake port, and the intake passage shape of the upstream portion of the air control valve is made substantially the same between each cylinder, and each intake port is a cylinder. It forms in the shape which produces longitudinal vortex inside, and it sets so that longitudinal vortex ratio 1.6-3.1 horizontal vortex ratio 1.8-3.5 at the time of lean air-fuel ratio operation.

FIG. 3 is provided with an air intake port shaped like a bell in a cylinder and an air control valve fitted in a part of the intake passage to form an opening.

4 shows an air intake port shaped into a longitudinal vortex in a cylinder and an air control valve mounted in an intake passage so that an opening is formed at an upper side and to one side of an almost horizontal mounting shaft, and the air control valve has a lean air-fuel ratio. At the time of operation, it is set so that the said opening part side may incline a predetermined amount downstream from a closed state.

5 is provided with an air control valve which is partially formed and the air control valve is set so that the opening is inclined by a predetermined amount in the closed state during the lean air-fuel operation, and the opening has a center line of the mounting shaft connecting the center point and the center of the passage. It is provided with two intake valves which are formed so that the angle to be made upwards in the range of 60-70 degree | times, and which are open-driven with a phase difference so that the thing of the air control valve opening side may open early.

According to the present invention, by having such a configuration, it is possible to form an optimum air flow place in the cylinder, thereby enabling lean air-fuel ratio operation in a larger air-fuel ratio region without impairing combustion stability.

Hereinafter, the operation to the effect of the present invention will be described with the experimental results according to the examples. In addition, in the following description and drawings, the air control valve is referred to as "SCV", which is an abbreviation of the horizontal vortex control valve, and the longitudinal vortex ratio and the horizontal vortex ratio are collectively referred to as "vertical vortex ratio horizontal vortex ratio". Shall be.

EXAMPLE

1 to 3 show an embodiment of a spark ignition type internal combustion engine of the present invention. In each figure, 1 is an engine main body, 2 is a cylinder, 3 is a cylinder head, 4 is a combustion chamber, 5 is a spark plug, 6 is an intake port, and 7 is an intake manifold.

As shown in FIG. 3, the intake manifold 7 branches the plurality of intake plates 9 extending from the intake collector assembly 8 to each intake port 6 of the engine 1 with the same length and It is provided in a symmetrical shape in the cylinder row direction.

In the vicinity of the junction portion of each intake cylinder 9 with the cylinder head 3, a passage adapter 10 for forming a straight intake passage of the same shape is provided between the cylinders, and air control is provided at a portion close to the intake port 6. The valve 11 is fitted.

The air control valve 11 is rotatably supported by a mounting shaft 12 installed almost horizontally to cross the passage adapter 10 and is in a closed position (shown state) when the lean air-fuel ratio operation is performed through an actuator (not shown). Controlled.

The air control valve 11 has an opening 13 partially formed as shown in FIG. In this case, this opening part 13 is formed in the state which cut out the part which shifted to one side from the upper side rather than the said mounting shaft 12 in this case.

As shown in FIG. 2, the air control valve 11 of the closed position is set so that the said opening part 13 side may incline by the predetermined amount (alpha) to the downstream side.

In this case, the intake port 6 branches in the middle so as to correspond to the intake valves 14 and 15 provided in two in the cylinder row direction. In addition, as a port shape for causing strong longitudinal vortex, as shown in FIG. 2, the angle θ formed by the center line of the horizontal plane is set small (θ = about 10 to 30 degrees).

In the present invention, for example, a spark ignition type internal combustion engine is constructed so that the longitudinal vortex ratio of in-cylinder intake flow is 1.6 to 3.1 and the horizontal vortex ratio is 1.8 to 3.5 during lean air-fuel ratio operation.

The characteristic of the port shape that strengthens the longitudinal vortex, ie, the longitudinal vortex in the cylinder, is that it has a linear shape and the angle θ of the passage centerline in the horizontal plane is small. In other words, the vertical air downward flow just under the intake valve on the cylinder center side of the intake stroke is suppressed as much as possible so as not to interfere with the generation of bells in the cylinder. The greater the air mass flow rate above the port, the greater the intensity of the longitudinal vortex ratio. Grows For example, in one type of internal combustion engine for small vehicles, it is effective for longitudinal vortex generation that θ is about 10 to 30 degrees and the radius R of the downstream curved portion thereof is 50 mm or more.

FIG. 4 shows the results of examining the combustion stability in lean combustion by changing the length of the intake pipe (branch) of the intake manifold and the length L (see FIG. 1) immediately upstream of the SCV at a predetermined ratio. The longer the intake pipe, the smaller the relative difference in intake pipe length between the cylinders. As can be seen from the figure, the smaller the difference in intake pipe length for each cylinder improves the combustion stability during lean combustion. have. That is, it is preferable that the intake manifold has the same length for each cylinder in order to obtain stable combustibility under the lean air-fuel ratio.

Moreover, in FIG. 4, the combustion stability is the best at the length of the linear part of the SCV upstream part about 100 mm. This corresponds to about 2.5 times the length of the inner diameter of the pot. In fact, it is possible to obtain the effect of improving the stability in lean burning of 1.5 to 3.5 times the inner diameter of the pot. This is because the difference in air flow in each cylinder is smoothed in the straight portion immediately upstream of the SCV, so that the air flow region in each cylinder becomes uniform.

In this way, with respect to the intake air, the intake pipes to the respective cylinders of the intake manifold have the same length, and particularly preferably intakes of approximately the same shape with each other having a length of 1.5 to 3.5 times the diameter in the port immediately upstream of the SCV. By installing the passage part, the air flow is equalized between the cylinders, and specifically, the combustion stability limit air-fuel ratio value is increased by about 1 to 1.5 (about 5% as a ratio) or more, which is expected to increase the combustion stability in lean combustion of the engine. do.

FIG. 5 shows the results of investigating the air-fuel ratio which becomes the stable combustion limit in lean combustion by changing the opening position of the SCV in various ways. In this figure, the longitudinal vortex ratio indicating the strength of the longitudinal vortex and the horizontal vortex ratio indicating the strength of the horizontal vortex are respectively optimal values. In general, the longitudinal vortex ratio is 1.6 to 2.2 and the horizontal vortex ratio is 1.8 to 3.2. Able to know. By increasing the output of the ignition system, the chance of poor ignition is reduced accordingly, so the vertical vortex ratio is 2.2 to 3.1 and the horizontal vortex ratio is 1.8 to 3.5.

In detail, when the longitudinal vortex ratio is strong, the generation of disturbance increases, and the stability during lean combustion is greatly affected by the generation of the disturbance, so that the line indicating the same combustion stability becomes close to horizontal as shown in FIG. On the other hand, when the longitudinal vortex ratio increases, the variation of the mean flow velocity per cycle for the same disturbance intensity as in FIG. 6 increases. As the fluctuation of the average flow velocity for each cycle increases, the air-fuel ratio which becomes the combustion stability limit moves in the dark direction as shown in FIG. In addition, as shown in the figure, in the MPi method of injecting and supplying fuel to each intake port, the influence of fluctuations in cycles of the average flow rate is higher than that of the SPi method in which the fuel for each cylinder is supplied upstream from the manifold assembly. Is strongly received and therefore it is more important to control it. In addition, when operating at the same air-fuel ratio, the combustion stability becomes worse as the longitudinal vortex ratio increases relatively. From these facts, it can be seen that the horizontal gap in the cylinder compensates for the drawback that the variation in the average flow velocity of each cycle has a great effect, and it has an effect of suppressing the variation in each cycle of the air flow.

FIG. 8 shows the optimum longitudinal vortex and horizontal vortex regions based on this knowledge. In this figure, it can be seen that the approximate longitudinal vortex ratio is in the range of 1.6 to 2.8 and the horizontal vortex ratio is in the range of 1.8 to 3.2. However, the results of FIGS. 5 and 8 are for the condition that the ignition system is not strengthened. In practical use, the air-fuel ratio which becomes the stable combustion limit is increased by using the enhanced ignition system. Is stable.

The strengthening of the ignition system is to increase the discharge period of the discharge voltage and increase the discharge energy. This generally requires improvement of the ignition coil and improvement of the durability of the spark plug that can withstand the large discharge energy. However, excessive reinforcement of the ignition system consumes engine power to drive energy of the ignition coil, which leads to deterioration of fuel efficiency, and at the same time promotes consumption of the spark plug.

Figure 9 shows the stable combustion limits for the longitudinal and horizontal vortex ratios of the ignition system strengthened to a practically acceptable level and is optimal with the longitudinal vortex ratio = 2.7 and the horizontal vortex ratio = 2.7. As described, the combustion improvement effect is seen in the range of the longitudinal vortex ratio of 2.2 to 3.1 and the horizontal vortex ratio of 1.8 to 3.5.

Next, the influence of the center position of the SCV opening on the combustion stability will be described. FIG. 10 shows the relationship between the center position of the SCV opening and the stable combustion limit air-fuel ratio in lean combustion. Assuming that the center position of the SCV opening has an optimum value and the effect of about 95% of the optimum value is obtained in consideration of manufacturing errors or differences in engine specifications, the angle formed by the mounting axis of the line segment drawn from the center of the opening to the opening center point (β) ) Should be in the range of 45 to 70 degrees, preferably β = 50 to 55 degrees. The combination of this opening configuration and the intake port (longitudinal vortex ratio reinforcement port) leading to the above-described longitudinal vortex enables the optimum values of the above-mentioned longitudinal vortex ratio = 2.7 and horizontal vortex ratio = 2.7 to be obtained.

It is also possible to generate longitudinal vortices with only SCVs with openings, without using longitudinal vortex-rendered pots. The advantage of being able to perform a combustion operation is obtained.

Next, a description will be given of setting the SCV upper portion to be inclined by a predetermined amount downstream of the flow in the closed position, thereby improving the combustion stabilizing effect as shown in FIG. This is because, as shown in FIG. 12, the flow of intake air into the SCV opening is cleared while the generation of the disturbance is left unchanged due to the inclination of the SCV, thereby suppressing cycle variation of the average flow rate. 13 shows the relationship between the SCV tilt angle α and the stable combustion effect.

As shown, the SCV tilt angle is in the range of 20 to 30 degrees, the most expected improvement in combustion stability. The range of the air-fuel ratio that can be set becomes smaller due to uneven mounting at the inclination angle, but the width of the air-fuel ratio that can be set by setting the SCV 'inclination angle in the range of 20 to 30 degrees is the maximum, and therefore, Even if there is an error, it can be sufficiently absorbed.

On the other hand, in the case of an engine having two intake valves as shown in FIG. 1 or FIG. 2, the intake valve (intake valve 15 in FIG. 1) opening to the SCV opening is opened earlier than the other side, so that combustion occurs as shown in FIG. Stability can be improved. This opens the intake valve on the side of the SCV opening first, thereby modifying it corresponding to the intake valve, so that an instrument for generating a horizontal vortex longitudinal vortex in one intake port corresponding to the intake valve is obtained stably and as a result, FIG. This is because fluctuations in the average flow velocity for each cycle are suppressed while the generation of the disturbance remains as it is.

As described above, the present invention obtains the optimum lean combustion operation performance by setting the longitudinal vortex ratio and the horizontal vortex ratio at about 2.7 before and after the intake manifold as a specific configuration for realizing the setting of the longitudinal vortex horizontal vortex ratio. To propose means such as symmetrical symmetry of the fold structure, setting of an air control valve having an opening at a predetermined position and its mounting inclination angle, forming a longitudinal vortex reinforcement port of the intake port, and setting the phase difference opening of the intake 2 valve; Each means is only one configuration example, and even when other configurations are employed, the optimum longitudinal vortex horizontal vortex ratio of the present invention can be set, thereby increasing the lean combustion limit or improving the stability of the lean combustion engine. have.

Moreover, in implementing each said means, they do not necessarily need to have all according to the specification of an engine, etc. For example, in a long stroke engine with a bore / stroke ratio of about 0.8 to 0.9, the piston speed is high, so the intake port does not necessarily need to be a longitudinal vortex reinforcement port, and the angle of inclination α of the SCV and the center angle of the SCV opening are described above. By optimizing (β) and setting the phase difference between the intake two valves, an optimum longitudinal vortex horizontal vortex ratio can be realized. In this case, however, it is preferable to reinforce the longitudinal vortex generation at the SCV opening as much as the one which does not perform the longitudinal vortex generation along the intake port, and for this purpose, for example, the center angle β as shown by reference numeral S of FIG. The range is set so as to be in the range of 60 to 70 degrees. The phase difference between the intake two valves is, for example, about 8 degrees at the crank angle as shown in FIG.

FIG. 16 shows each of the above means for embodying the present invention and the effects of combining some of them with a combustion limit air-fuel ratio. Longitudinal vortex reinforcement port (means D of the present invention above) compared with the conventional example in which only the SCV is set in the engine of the intake two-valve type as shown. Equivalent length symmetry of the intake machine including the SCV inclined mounting (a of the moving means B) and the linear same shaping immediately before the SCV (the moving means A.C). Even if the phase difference opening setting of the intake two valves (the copper means E) and the like are applied to each other, a certain combustion limit improvement effect can be obtained, but in particular, after combining them, the SCV opening center position is optimally set (b of the copper means B). Remarkable effects as can be seen in the graphs of symbols 5, 9 and 10 in the figure are obtained. In addition, in the case where a phase difference is provided to the intake two valves, a sufficiently improved combustion improvement effect can be obtained even in the configuration in which the longitudinal vortex strengthening port is not provided as indicated by reference numeral 11.

[Effects of the Invention]

In summary, the present invention is a cylinder which is effective for stabilizing combustion in lean combustion by ensuring adequate disturbance by longitudinal vortex components and suppressing cycle variation of average flow rate by horizontal vortex components in a spark ignition type internal combustion engine. On the basis of the knowledge that the internal air flow area is obtained, the optimum longitudinal vortex ratio and the horizontal vortex ratio can be given, and as a specific means for realizing this, the equivalent length of the intake pipe configuration, symmetry, and opening of the air control valve It proposes the configuration of the center position, the inclination of the inclination of the air control valve, the intake two-valve type that opens with the longitudinal vortex reinforcement port shape phase difference, etc. Effects of improving combustion stability in lean burn zones It can be achieved.

Claims (10)

In a flame-gradual internal combustion engine that diminishes the air-fuel ratio according to the operating conditions, a plurality of intake pipes branched from the intake collector collection unit to each intake port of the engine are arranged in a symmetrical shape in the same length and cylinder row direction. In addition, an air control valve having an opening part and controlled in a lean air-fuel ratio operation so that the opening is inclined by a predetermined amount in the closed state is inserted near each intake port, and an intake passage immediately upstream of the air control valve is mounted. A flame ignition type internal combustion engine, characterized in that the shape is equalized between the cylinders, and each intake port is formed in a shape causing longitudinal vortex in the cylinder. The spark ignition type internal combustion engine according to claim 1, wherein the vortex air-fuel ratio is set so as to have a longitudinal vortex ratio of 1, 6 to 3.1 and a horizontal vortex ratio of 1.8 to 3.5 during lean air-fuel ratio operation. The air control valve of claim 2, wherein the air control valve has an opening formed at an upper side and to one side of the horizontal mounting shaft, and the air control valve inclines a predetermined amount toward the downstream side in a closed state during lean air-fuel ratio operation. A spark ignition type internal combustion engine, characterized in that it is set to be. A spark ignition type internal combustion engine that thins an air-fuel ratio according to an operating condition, wherein an opening is partially formed, and when the lean air-fuel ratio operation is provided, an air control valve is set so that the opening is inclined to a downstream amount in a closed state. Is formed so that the angle formed by the center line of the mounting shaft of the line connecting the center point and the passage center is in the range of 60 to 70 degrees upwards, while the opening valve is driven with a phase difference so that the air control valve opening side is opened early. A spark ignition type internal combustion engine comprising two intake valves. The spark ignition type internal combustion engine according to claim 1 or 2, wherein a predetermined amount of the inclination angle of the air control valve during the lean air-fuel ratio operation is set within a range of 20 to 30 degrees with respect to a cross section perpendicular to the central axis of the intake passage. . The flame ignition type internal combustion engine according to claim 1 or 2, wherein the length of the same intake passage for each cylinder immediately upstream of the air control valve is set within a range of 1.5 to 3.5 times the diameter in the intake port. The spark ignition type internal combustion engine according to claim 1 or 2, comprising two intake valves driven with a phase difference so that the intake valve on the air control valve opening side is opened early. The flame-gradual internal combustion engine according to claim 1 or 2, wherein the air control valve has an opening formed at an upper side of the mounting shaft and in a radially biased portion. The spark ignition type according to claim 1 or 2, wherein the opening of the air control valve is set within a range of 45 to 75 degrees upward from an angle formed by the mounting shaft center line of the line segment connecting the center point to the center of the passage. Internal combustion engine. The spark ignition type internal combustion engine according to claim 1 or 2, wherein the intake port having a longitudinal vortex in the cylinder is formed in a straight line with a small angle at which the center line forms a horizontal plane.