JPS6245935A - Swirl controller - Google Patents

Abstract

PURPOSE:To aim at improvement in a rate of fuel consumption, by installing a swirl ratio variable valve mechanism in the subport system connected to a main port for swirl generation with an angle, and controlling this mechanism according to both maps in use at the times of ordinary driving and free acceleration. CONSTITUTION:A variable swirl suction system is constituted of a main port 9 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 controls it so as to secure each selected swirl ratio according to a map M, in use at the time of ordinary driving, selecting an optimum swirl ratio on the basis of engine load and revolution at the time of ordinary driving in an engine, and at the time of free acceleration, according to another map (unillustrated herein), in use at the time of free acceleration, setting such a swirl ratio as taking a time lag into account.

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 heir swirl port (forced full flow intake hole) called I (SP tank structure).

As shown in FIG. 15 (5) (I3), the intake port 01 is provided with the intake port 01 slightly centered relative to the center of the intake valve 02, and the intake port 01 is opened when the intake valve 02 is lowered. The intake air deflected by the intake port 01 during the stroke is guided into the combustion chamber 03, 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 fuel efficiency, so a low swirl ratio is advantageous from this point of view as well.

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. 724.3/1983 has been proposed in order to make the swirl ratio variable.

This is as shown in Figure 16 fA) (B), where 112 is a combustion chamber, 115 is an intake port, and 116a is a combustion chamber.
is the intake valve seat. The intake port 115 has a structure based on a low swirl type, and is divided into left and right ports 115a and 115b by a partition wall 117, and one port 1.115b can be opened and closed by an on-off valve 118. be.

When the on-off valve 118 is opened as shown in FIG.
Then it will be in a low swirl state. When the on-off valve 118 is closed as shown in FIG. 1), intake air is guided only to one port 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. That is, in a low swirl state, as shown in FIG. 17 (5), a swirling flow similar to a rigid body vortex is simply generated in the combustion chamber 112, and as shown in FIG. Injection iF injected radially from the center of the combustion chamber 112
. . . can only have the effect of receiving a crosswind from the rigid body swirl shown by the arrow in the figure, and therefore sufficient mixing of the spray F . . . and air cannot be obtained. Furthermore, in a high swirl state, as shown in FIG. There are losses such as multiple eddy currents and backflow.Also, the cross-sectional area of the flow path is halved, and the narrow cross-sectional area of the port 115a causes a large amount of flow resistance. Since intake air does not flow into the combustion chamber 112,
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. 16 (5) (Bl), the intake port 115 is simply divided into two parts, and the intake direction is not changed as each swirl state is changed. Even in this state, it appears as a reduction in the amount of intake air.

Although various other structures are available, they all fail to vary the swirl state while always ensuring a sufficient amount of intake air, and their complex 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 bow 1 is considered, which consists of a sub-port connected at a certain angle and independent of the main port, and it is intended to change the swirl ratio 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 above-mentioned variable swirl port as an intake system to obtain the optimum swirl ratio corresponding to the various conditions mentioned 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 that is connected to the upstream side of the intake valve of the combustion chamber and makes the air flowing into the combustion chamber into a swirl flow. A variable swirl intake system consisting of a sub port connected at an angle near the end of the main 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. A swirl map for normal operation that determines the optimal swirl ratio based on the valve mechanism and engine load and rotational speed during normal engine operation, and a swirl map for free acceleration that determines the swirl ratio that takes into account time delays during engine free acceleration operation. and a control system that selects an optimum swirl ratio from the map according to the operating condition of the engine and outputs an operation command to the valve mechanism.

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, and 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 for obtaining a high swirl ratio when external air is guided to flow into the combustion chamber 6 through the entire intake valve seat 7. It becomes. 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 it is approximately vertical, the auxiliary air passage 13 is fully closed. Become. By adjusting the opening degree 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 ports 1 to 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 the swirl ratio of the intake air introduced into the combustion chamber 6 is desired to be high, and is opened when the swirl ratio is desired to be low. The condition can be explained from Figure 5 (0'3).In other words, in each figure (8), the intake valve seat 7 is divided into 8 equal parts.
Attach a number. At each numbered position, intake air is drawn into the combustion chamber 6 in the direction indicated by the arrow in the figure and with a strength corresponding to the length of the arrow. Swirl components numbered 1 to 4 also indicate that in the combustion chamber 6, the intake direction at the main port 9 is at the center 0 of the combustion chamber 6.
1. Since it follows the clockwise direction (g) created around 1, it becomes a forward swirl direction component, and these moments become similar swirl direction moments j. Swirl components numbered 5 to 8 try to rotate in the counterclockwise direction (c) around the center O1, so they become reverse swirl components, and their moments become reverse swirl direction moments. In each figure (B), the magnitude of the swirl component moment of each number is
The forward and reverse directions are indicated by arrows. In addition, 02 (Yo intake valve seat 7
is the center point of In the case of FIG. 4 (A303), since the sub-port 10 is closed, the difference between the sum of forward swirl direction moments and the sum of reverse swirl direction moments is sufficiently large, resulting in a high swirl state as a whole.

However, in the case of Fig. 5 (A) 03), the sub port 10
Since this is open, the intake air is also guided into the combustion chamber 6 from here, and the moment in the reverse swirl direction becomes especially large near numbers 6 and 7.

The sum of moments in this direction approaches the sum of moments in the forward swirl direction. The intake air in the forward swirl direction in the combustion chamber 6 collides with the intake air in the reverse swirl direction led from the auxiliary port 10, and cancel each other out to obtain a low swirl state. However, as the intake flow rate, the amount flowing in from the sub port 10 in addition to the amount flowing in from the main port 9 is originally 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 speed range, a low swirl state is good as described 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 FIG. 6 (5) (I3), there is a forward high swirl from the main port 9 (indicated by the white arrow in the figure) and a reverse swirl from the sub port 10 (indicated by the black arrow in the figure). The two vortices interfere with each other in the combustion chamber 6, generating two vortices with different rotational directions, and also generating many small vortices or turbulence around these vortices.

These many vortices or turbulences remain to some extent even after the compression stroke, and as shown in the same figure [C], improve the mixing of the spray F with air, improve combustion efficiency, and reduce smoke and exhaust gas. useful for. In a high swirl state, as shown in FIG. 7, the intake air is guided smoothly and without loss along the streamlined and smooth main port 9 shape at the minimum necessary speed.

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. Note that the secondary port 10 does not adversely affect the flow of intake air in the main port 9 in a high swirl state.

The opening/closing movement of the actuator 5 is controlled by a control unit serving as a control system. The control unit 16 has an optimum sw
121M is stored. This swirl map M is
Based on the load and rotational speed of the engine 1, the optimum swirl ratio for the operating state can be selected. The load on the engine 1 is determined by detecting when the accelerator pebble 17 is depressed, the rotational speed (Ne) of the engine 1 is detected by the tacho generator 18, and the control unit 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 jJ+ and dp/d when the swirl ratio is changed.
The graph shows the tendency of the relationship between the amount of change in θ and the amount of change in Pma when the swirl ratio is changed. 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. Pma 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/dθ 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% (midway), and a high swirl ratio at 30% (low speed) in terms of fuel efficiency and exhaust gas temperature.

As shown in Figure 10, 4/4 at low speed 45% Ne,
At 374 and 274 loads, fuel efficiency and exhaust gas concentration are better with a higher swirl ratio, but at lower loads,
The lower the swirl ratio, the better 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.

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

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. In addition, 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 Pma and improves engine durability. dp/dθ is also lower, noise is reduced), and it is advantageous in all respects.

The swirl map M obtained by taking the above into consideration is a high swirl ratio at least in low speed and high load areas, and medium in other areas.

The swirl ratio is low.

In the swirl map M shown in Fig. 1, the low speed/low load area is the medium swirl ratio area, the low/medium/high speed/low load area is the low swirl ratio area, the low/medium speed/medium/high load area is the medium swirl ratio area,
The medium-high speed and medium-high load areas are defined as low swirl ratio areas.

During normal operation of the engine 1, the swirl ratio is controlled based on the map M.

In other words, the optimum swirl ratio is determined according to the load and rotational speed of the engine 1, and the actuator 15 is controlled so as to obtain the swirl ratio, thereby changing the amount of air sucked into the combustion chamber 6 from the auxiliary port 10. It is.

By the way, engines are operated in various ways.
Regardless of the operating state, the amount of NOx emissions and the concentration of flue gas must be below specified values. During free acceleration, where the engine is revved several times in succession, the engine speed and load change as shown in FIG.

When you step on the accelerator from a low idle state, the engine accelerates, and the governor works to maintain a constant rotation (high idle) balanced with a constant load. At this time as well, the swirl ratio is changed depending on the engine speed and load, but the transition from low idle to high idle is made in an extremely short time (about 1 second).

In FIG. 13, the transition from low idle to high idle in map M for normal operation is shown by a solid line. Although the transition from low idle to high idle is made in an extremely short time as described above, the change in swirl ratio is actually made with a delay due to delays in the valve mechanism, etc. However, in this case, the optimal swirl map M determined based on the engine's -19 load and rotational speed will not be utilized.

Therefore, during free acceleration, the swirl ratio is controlled based on a map M' as shown in FIG. 14, which takes into account the delay in operation. In other words, during free acceleration, the swirl ratio switching signal is issued early,
At high idle, the optimum low swirl ratio is achieved. For example, if it takes 0.4 seconds to switch the swirl ratio, map M' in FIG. 14 will have a low swirl ratio when exactly 60% Ne< or so, resulting in an optimal swirl switching pattern.

There are various ways to detect the free accelerator, and one example is the accelerator pedal 17.
There is a method for detecting the idling operation. If the increase in engine rotational speed as measured by the tachometer exceeds a certain value, this is determined to be engine racing, and in order to distinguish it from double clutch operation, it detects when engine engine speed continues two or more times.
This is determined to be the time of free acceleration, and based on this determination, the map is switched to that of the time of free acceleration, and a timer is set for the time during which this map M' is adopted. After a certain period of time has elapsed, control is switched to normal map M-based control.

Furthermore, as another example, a method may be considered in which a case where the displacement speed of the accelerator pedal 17 is equal to or higher than a certain value is determined to be idling, and the state is determined to be a free accelerator.

<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.

4. Brief explanation of planes Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a schematic diagram of an embodiment of the engine in section along a plane, and Fig. 3 is a part of the engine. The side sectional view of FIG. 4 (5) is a diagram illustrating the swirl component in a high swirl state.
) is a diagram explaining the swirl direction moment in the same state, FIG. 5 (5) is a diagram explaining the swirl component in a low swirl state, FIG. Figure 6 (Al is a perspective view explaining the low swirl state, Figure (I3) is a perspective view also explaining the swirl state, Figure 6 (q is a diagram explaining the spray state, Figure 7 is a diagram explaining the intake state) Figures 8 to 12 are diagrams showing the relationship between swirl ratio and NOx emissions, fuel efficiency, exhaust gas concentration, etc., and Figure 13 is a map for normal operation from low to high idle. Figure 14 is an explanatory diagram of the map during free acceleration, and Figure 15 (5) is a cross-sectional plan view of a normal intake system. Cross section, 16th
Fig. 17 (5) 031 is a schematic plan view of a conventional variable swirl port, Fig. 17 (5) is a schematic perspective view thereof, and Fig. 17 (C) is an explanatory diagram of the spray state. It is a diagram.

In the drawing, 1 is the engine, 6 is the combustion chamber, 8 is an intake valve; 9 is the main port, 10 is the sub port, 11 is the intake manifold, 14 is a valve; 15 is an actuator; 16 is Con J ~ roll unit, M optimal swirl map, M' is a map during free acceleration.

Patent applicant Mitsubishi Motors Corporation People

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 swirl ratio of the swirl flow in the combustion chamber by changing the amount of air flowing through the auxiliary port in the variable swirl intake system, and a normal valve mechanism that determines the optimum swirl ratio based on the engine load and rotation speed during normal operation of the engine. Equipped with a swirl map for driving and a map for free acceleration that determines the swirl ratio taking into account time delay during free acceleration operation of the engine,
A swirl control device comprising: a control system that selects an optimum swirl ratio from the map according to the operating condition of the engine and outputs an operation command to the valve mechanism.