JPS6245933A - Swirl control device - Google Patents

Abstract

PURPOSE:To make improvements in a rate of fuel consumption so better, by installing a main port for swirl flow generation and the subport connected to the former with an angle, and controlling a swirl ratio variable valve mechanism to be installed in a subport system according to a map having an oblique boundary. CONSTITUTION:A variable swirl suction system is constituted of a main port 9 being installed eccentrically to the center of a suction valve and making air to be flowing in a combustion chamber 6 turn to a swirl flow, and the subport 10 connected to a spot proximate to a terminal part of the said port 9 with an angle. A valve body 14 to be opened or closed by an actuator 15 is installed in a sub-air passage to be connected to the subport 10. And, the actuator 15 selects an optimum swirl ratio by a control unit 16 on the basis of load, revolution, etc., of an engine, controlling it so as to secure the said swirl. The control unit 16 is constituted of installing a map M which consists of partition off a zone of the swirl ratio to be selected with an oblique boundary in line with an increase in engine speed and load.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for intake air swirl formed in a combustion chamber (cylinder chamber) of an engine.

<Prior art> For example, the cylinder head of a direct injection diesel engine is provided with an intake port for guiding air into the combustion chamber, and the intake valve provided in this intake port opens and closes according to each stroke of the engine. It is supposed to be done.

The air introduced into the combustion chamber from the intake port is compressed, mixed with the fuel injected from the injection nozzle, and then exploded and combusted. It is well known that the better the mixture of air and fuel, the better the combustion efficiency. It is.

Conventionally, various means have been used to improve the mixing state of air and fuel, one of which is a high swirl port (forced swirl intake hole) called the H3P structure.

This is due to the intake port 0 as shown in Figure 14 (Nβ).
1 is provided slightly eccentrically with respect to the center of the intake valve 02, and during the intake stroke when the intake valve 02 is lowered and the intake ball l-01 is opened, the intake air deflected by the intake port 01 flows into the combustion chamber 0.
3, and a swirl is forcibly formed along the circumferential direction. Therefore, the mixing state of the intake air and the fuel injected from the injection nozzle is improved, and the combustion efficiency is improved.

It is desirable that the strength of the swirl formed in the combustion chamber be variable depending on various conditions. The strength of the swirl is determined by the ratio of the rotation speed of the intake air in the combustion chamber to the engine speed (
It is expressed as the swirl ratio.

Regarding the relationship between swirl ratio and engine performance, it is known that when the engine speed is low, it is better to increase the swirl ratio, and when the engine speed is high, it is better to decrease the swirl ratio in terms of engine performance. There is.

The magnitude of the swirl ratio is also related to the amount of NOx (nitrogen oxides) generated, and it is known that the higher the swirl ratio, the greater the amount of NOx generated.

Also, regarding the load of the engine, a low swirl ratio is optimal at low speeds and low loads, and even at medium speeds, a low swirl ratio is sufficient from light to medium loads, and at high speeds, a low swirl ratio is optimal regardless of the load condition. Swirl ratio is optimal.

Furthermore, regarding the relationship between the swirl ratio and heat loss, the lower the swirl ratio, the lower the heat loss absorbed by the cylinder wall from the combustion gas. Particularly under light loads, the magnitude of this heat loss corresponds to deterioration or improvement of the fuel consumption rate, so a low swirl ratio is also advantageous from the point of point (B).

Since there is an optimum swirl ratio depending on various conditions as described above, a mechanism as shown in, for example, Japanese Patent Publication No. 7243/1983 has been proposed in order to make the swirl ratio variable.

This is shown in Figure 15 (5) Q31,
In the figure, 112 is a combustion chamber, 115 is an intake port, and 116a is an intake valve seat. The above-mentioned intake port 115 has a structure based on a low swirl type, and has bows 1-115a and 115b divided into left and right by a partition wall 117, and one bow 1-115b can be opened and closed by an on-off valve 118. It is free.

When the on-off valve 118 is opened as shown in (5) in the figure, intake air is guided to both bows 115a and 115b, and the flow rate passing through the intake valve seat 116a is slow, resulting in a low swirl state in the combustion chamber 112. . When the on-off valve 118 is closed as shown in β) in the figure, intake air is guided only to one bow 1-115a. The cross-sectional area of the intake flow path is halved, and the intake valve seat 1
Since the intake air is narrowed to an area larger than the inner diameter area of the combustion chamber 16a, the flow velocity of the intake air increases, and a high swirl state is created in the combustion chamber 112. The swirl component in each state has the direction and strength shown by the arrow in the figure.

With this type of structure, the swirl ratio can be varied as required, but there are drawbacks as described below. In other words, in a low swirl state, as shown in FIG. 16 (5), only a swirling flow similar to a rigid body vortex is generated in the combustion chamber 112, and as shown in the figure Injection NF is injected radially from the center of the combustion chamber 112.
Since the effect is only that of receiving a cross wind from the rigid body vortex shown by the arrow in the figure, sufficient mixing of the spray F... and air cannot be obtained. Furthermore, in a high swirl state, the same figure (Q
As shown in FIG.
After passing the end of the partition plate 117, the area of the flow path suddenly increases. Therefore, a plurality of eddy currents occur due to separation, and losses such as backflow occur. In addition, the cross-sectional area of the flow passage is halved, and the narrow cross-sectional area of Kabo 1-115a causes a large flow resistance, and the intake air flows into the combustion chamber 112 only from a part of the intake valve seat 116a, so the flow coefficient is low and the amount of intake air is insufficient.

The basic idea regarding swirl is that if a high swirl state is desired, it is desirable to have intake air flow into the combustion chamber from the horizontal direction (circumferential direction), and in this case, the amount of intake air is small.

If a low swirl state is desired, it is desirable to allow intake air to flow into the combustion chamber from the vertical direction (axial direction), and in this case, the amount of intake air will be large.

However, in the conventional structure shown in FIG. 15 (Al(g)), the intake port 115 is simply divided into 1 minute.
The intake direction does not change with the switching of each swirl state, and the amount of intake air appears to be reduced in each state.

In addition, various other structures are available, but all of them do not allow the swirl state to be varied while always ensuring a sufficient amount of intake air, and their complicated structures have a negative impact on cost.

<Problems to be Solved by the Invention> In order to solve the drawbacks of the conventional variable swirl structure as described above, the main port (intake port) connected to the upstream side of the intake valve and the A variable swirl port is considered that is connected at a certain angle and consists of a sub-port independent of the main port, and the swirl ratio is changed by changing the amount of air flowing through the sub-port.

This swirl port allows the swirl ratio to be changed without reducing the amount of air taken into the combustion chamber.

The present invention uses the variable swirl port described above as an intake system to obtain the optimum swirl ratio according to the various conditions described above, thereby improving engine performance, fuel efficiency, and N.
The purpose is to reduce Ox.

Means for Solving the Problems> The configuration of the present invention for achieving the above object includes a main port connected to the upstream side of the intake valve of the combustion chamber and making the air flowing into the combustion chamber into a swirl flow. A variable swirl intake system consisting of a sub port connected at a certain angle near the terminal end of the port, and a swirl ratio of the swirl flow in the combustion chamber by changing the amount of air flowing through the sub port in the variable swirl intake system. =7- a control system that selects a swirl ratio based on engine load, engine speed, etc. and operates the valve mechanism; and a control system that selects a swirl ratio based on engine load, engine speed, etc. The swirl control device is characterized by comprising a map configured by partitioning a range of swirl ratios to be controlled by diagonal boundaries as the engine speed and engine load increase.

Embodiment FIG. 1 shows a schematic configuration of an embodiment of a swirl control device according to the present invention, FIG. 2 shows a schematic configuration of an engine in cross section along a plane, and FIG. This shows a side cross section of the engine.

1 is an engine, 2 is its cylinder block, 3 is a cylinder liner, 4 is a piston, 5 is a cylinder head connected to the upper part of the cylinder block 2, 6 is a cylinder liner 3
, a piston 4, and a cylinder head 5. The cylinder head 5 is provided with a variable swirl intake system, and 7 is the cylinder head 5.
8 is an intake valve that opens and closes the intake valve seat 7; 9 is a main port provided on the upstream side of the intake valve 8;
Reference numeral 10 denotes a sub-port independent of the main port 9, which is connected to the terminal end of the main port 9 (in this embodiment, the end of the winding). The main port 9 is provided slightly eccentrically with respect to the center of the intake valve 8, and has an optimal shape to obtain a high swirl ratio when external air is guided into the combustion chamber 6 through the intake valve seat 7. ing. Further, the sub-port 10 is connected to the terminal end of the main port 9 at a certain angle, so that air can be smoothly supplied to the combustion chamber 6. The intake valve 8 is driven to open and close the intake valve seat 7 at appropriate timings. Although omitted in the figure,
The cylinder head 5 is provided with an exhaust system consisting of an exhaust valve, an exhaust port, etc., and is also provided with a fuel injection nozzle facing the combustion chamber 6.

An intake manifold 11 is connected to the cylinder head 5, and a main air passage 12 and a sub air passage 13 of the intake manifold 11 are connected to a main port 9 and a sub port 10, respectively.

The auxiliary air passage 13 is provided with a valve body 14 for opening and closing the passage 13, and an actuator 15 for opening and closing the valve body 14 is connected to an end of the valve body 14. The valve portion 14a of the valve body 14 is plate-shaped, and when the valve portion 14a is approximately horizontal, the passage 13 is fully open, and when the valve portion 14a is approximately vertical, the auxiliary air passage 13 is fully closed. .

By adjusting the opening of the auxiliary air passage 13 by operating the actuator 15, the amount of air flowing therethrough is adjusted, that is, the amount of air entering the combustion chamber 6 from the auxiliary port 10 is adjusted, and the swirl is changed.

During the intake stroke when the intake valve 8 descends and the main port 9 opens, the intake air is guided into the combustion chamber 6 via the intake valve seat, where a swirl is forcibly formed along its circumferential direction. It will be done. This air is mixed with fuel injected from an injection nozzle (not shown) and combusted.

The valve body 14 is closed when a high swirl ratio of intake air introduced into the combustion chamber 6 is desired, and opened when a low swirl ratio is desired. The high swirl state can be explained from Fig. 4 (Al (81), low swirl state (Fig. 5 (5) (I3)).In other words, in each figure (5), the intake valve seat 7 is divided into eight equal parts, and the The position of each number corresponds to the direction shown by the arrow in the figure, and the intake air with the strength corresponding to the length of the arrow is drawn into the combustion chamber 6.The swirl components numbered from 1 to 4 are , also in the combustion chamber 6, since the intake direction at the main port 9 follows the clockwise direction (G) created around the center 01 of the combustion chamber 6, it becomes a forward swirl direction component, and these moments become forward swirl direction moments.From number 5 The swirl component of 8 tries to rotate in the counterclockwise direction (c) around the center 01, so it becomes a reverse swirl component, and these moments) and become reverse swirl direction moments.In each rotation part), each number The magnitude of the swirl component moment is shown by arrows in the forward and reverse directions. Note that o2 is the center point of the intake valve seat 7. As a result, the difference between the sum of moments in the forward swirl direction and the sum of moments in the reverse swirl direction is sufficiently large, resulting in a high swirl state as a whole.

However, in the case of Fig. 5 (A) and (B), the sub port 1
Since No. 0 is open, intake air is also guided from here to the combustion chamber 6, and the moment in the reverse swirl direction is especially large near No. 6 and No. 7.

The sum of moments in this direction approaches the sum of moments in the forward swirl direction. The intake air in the similar swirl direction in the combustion chamber 6 collides with the intake air in the opposite swirl direction led from the sub-port 10, and cancel each other out to obtain a low swirl state. However, the intake flow rate is originally the main port 9.
In addition to the amount flowing in from the auxiliary port 10, the amount flowing in from the sub port 10 is secured. Furthermore, since the auxiliary port 10 stands nearly vertically, intake air flows smoothly into the combustion chamber 6. Therefore, the swirl state is low and the amount of intake air is sufficient. Particularly when the engine is in a high rotation range, a low swirl state is good, as explained above, and by opening the sub port 10, a sufficient amount of intake air can be secured to achieve this state. Also, as shown in Figure 6 (Al (Bl),
The forward high swirl from the main port 9 (indicated by the white arrow in the figure) and the reverse swirl from the auxiliary port 10 (indicated by the black arrow in the figure) interfere with each other in the combustion chamber 6, causing a difference in the rotation direction. In addition to generating two vortices, many small vortices or disturbances are also generated around these vortices.

These many vortices or turbulences remain to some extent even after the compression stroke, and as shown in the same figure (q), improve the mixing of the jet FJF... with air, improve combustion efficiency, and reduce smoke and exhaust gas. In a high swirl state, the intake air is guided smoothly and without loss at the minimum necessary speed along the streamlined and smooth main port 9 shape as shown in FIG.

Moreover, since the intake air is evenly introduced into the combustion chamber 6 from the entire circumference of the intake valve seat 7, the swirl is high and the amount of intake air is also very large. It should be noted that in the high swirl state, the secondary port 1.1.0 does not adversely affect the flow of intake air in the main port 1-9.

The actuator 15 is controlled to open and close by a control unit serving as a control system. The control unit 16 stores an optimum swirl map M that serves as a reference for the operation of the actuator 15. This swirl map M is such that the optimum swirl ratio for the operating condition can be selected based on the load and rotational speed of the engine 1. still,
The load on the engine 1 is determined by detecting the amount of depression of the accelerator pedal 17, and the rotational speed (Ne) of the engine 1 is detected by the tachogenerator 18 and input to the control unit 16. In the figure, 19 is an injection pump.

The optimum swirl map M stored in the control unit 16 is determined so as to obtain the optimum operating condition according to the load and rotation speed of the engine 1, and the relationship between the swirl ratio and each performance is the basis for this judgment. are shown in FIGS. 8 to 11.

Figure 8 shows the relationship between the swirl ratio and NOx emissions at six mode values, and Figure 9 shows the relationship between the swirl ratio, fuel efficiency, and exhaust gas concentration at different rotational speeds under full load. Figure 10 shows an example of 45% Ne (
Figure 11 shows the relationship between the swirl ratio at low speeds, the fuel efficiency rate, and the exhaust gas concentration at different loads. Figure 12 shows the relationship between fuel consumption rate and dp/ll at a certain engine speed and load.
The graph shows the tendency when the swirl ratio is changed in relation to the amount of change in θ and the amount of change in Pmaχ. Figures 11 and 12
In the figure, a, b, c-j are measurement points, and the numbers in the figure are swirl ratios as an example. Pmaχ in FIG. 12 is the maximum cylinder pressure, and serves as a guide for determining the durability required of the engine. Further, dp/dθ indicates the change in cylinder pressure with respect to time, and serves as an indicator of noise generation. It is desirable that all of these Pmaχp dp/'θ have low values.

As shown in FIG. 8, in the 6-mode value, the smaller the swirl ratio, the more the NOx is reduced.

As shown in Figure 9, the engine speed Ne is 100% (
It is better to have a low swirl ratio at high speed), a medium swirl ratio at 65% (medium speed), and a high swirl ratio at 30% (low speed) in terms of fuel efficiency and exhaust gas temperature.

As shown in FIG. 10, 474.
At a load of 374.274, a high swirl ratio results in better fuel efficiency and exhaust gas concentration, but at a lower load, a lower swirl ratio improves the fuel efficiency. The reason is that light loads are more susceptible to cooling losses.

Since the heat transfer from the combustion gas to the cylinder liner, piston, lower surface of the cylinder head, etc. is proportional to the nth power of the gas flow velocity, under light loads, the smaller the swirl speed, the better the fuel efficiency.

Furthermore, as shown in FIG. 11, the lower the swirl ratio, the lower the NOx in all operating conditions of the engine.

Furthermore, as shown in Fig. 12, as the swirl ratio is lowered, Pma becomes p
/dθ is reduced, improving engine durability and reducing noise.

Therefore, as a general rule, a low swirl ratio is selected in areas where there is no significant difference in performance even if the swirl ratio is changed. Also, at high speeds and partial loads at low and medium speeds, lowering the swirl ratio not only improves fuel efficiency, but also reduces NOx and cleans exhaust gas), reduces Pmaχ and improves engine durability), dp /dθ is also lower, noise is reduced), which is advantageous in all respects.

The swirl map M obtained by taking the above into consideration is a high swirl area in the low speed/medium/high load area, a medium swirl ratio in the low/medium speed/low/medium/high load area, and a low swirl area in the medium/high speed/low/medium/high load area. It is.

FIG. 1 shows a diagram in which the boundaries of each area are divided diagonally in the manner described above.

The value of the swirl ratio for each region (for example, a high swirl ratio of 43, a medium swirl ratio of 33, and a low swirl ratio of 20).

FIG. 13 shows a swirl map M according to another example.

This is a swirl ratio region divided into four based on the above-mentioned conditions.

Based on the above map, the optimum swirl ratio is selected according to the load and rotation speed of the engine 1, and the control unit 16 controls the actuator 1 so that the swirl ratio is selected.
A swirl instruction signal is output to 5, and the actuator 15 is operated in accordance with this swirl instruction signal to adjust the opening degree of the valve 14, thereby changing the amount of air sucked into the combustion chamber 6 from the sub port 10, and creating a swirl. The ratios are changed and the engine is operated at optimum conditions.

<Effects of the Invention> According to the swirl control device according to the present invention, the intake system is configured as a variable swirl intake system consisting of a main port and a sub-port so that the swirl state can be easily changed, and a sufficient amount of air is always maintained. Furthermore, the optimum swirl ratio can be selected depending on the engine operating condition, improving combustion efficiency and reducing NOx in exhaust gas.
The exhaust gas concentration can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an embodiment in which the engine is cut along a plane, and FIG.
The figure is a sawn section I diagram of a part of the engine, FIG.
Figure 5 (5)-19= is a diagram explaining the swirl component in a low swirl state, the same diagram (131 is a diagram explaining the swirl direction moment in the same state, and Figure 6 (5) is a diagram explaining the low swirl state) (B) is a perspective view illustrating the swirl state; q is a perspective view illustrating the spray state; FIG. 7 is a perspective view illustrating the intake state; The figure is a diagram showing the relationship between the swirl ratio and NOx emissions, fuel efficiency, exhaust gas concentration, etc., Figure 13 is an explanatory diagram of an example of an optimal swirl map, and Figure 14 (5) is a cross section of a normal intake system. Plan view,
The same figure (Bl is a cross-sectional view along the B-B line, Figure 15 (A
) (Bl is a schematic plan view of a conventional variable swirl port, the 16th rotation is a schematic perspective view thereof, (B) is an explanatory diagram of the spray state, and (q is an explanatory diagram of the intake state). In the figure, 1 is the engine, 6 is the combustion chamber, 8 is the intake valve, 9 is the main port, 10 is the sub port, 11 is the intake manifold, 14 is the valve, 15 is the actuator, 16 is the control unit, M, M, are This is an optimal swirl map.

Claims (1)

[Claims] a variable swirl intake system comprising a main port connected to the upstream side of an intake valve of a combustion chamber and making air flowing into the combustion chamber into a swirl flow; and a sub port connected at an angle near the terminal end of the main port; A valve mechanism that changes the amount of air flowing through the sub-port in a variable swirl intake system to change the swirl ratio of the swirl flow in the combustion chamber; and a valve mechanism that selects the swirl ratio based on engine load, rotation speed, etc. A control system to be operated; and a map configured by partitioning a swirl ratio region selected according to engine speed and engine load in the control system with diagonal boundaries as the engine speed and engine load increase; A swirl control device comprising: