JPH0531218Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to an intake system for an internal combustion engine having a helical intake port.

<Prior Art> A helical intake port is usually provided with a spiral portion surrounding an intake valve at the terminal end of the intake port in the cylinder head of an engine. The swirl section gives a swirling flow to the intake air, and when the intake valve opens, this swirling flow is introduced into the combustion chamber to form a large swirl in the combustion chamber, promoting combustion by promoting the mixing of air and fuel. trying to improve.

By the way, if we take the above-mentioned direct injection diesel engine equipped with a helical intake port as an example,
As shown in Figure 5, it is desirable that the swirl ratio (intake swirl speed relative to the rotational speed of the engine crankshaft) gradually decreases as its optimum value moves from the engine's low-speed rotation region to its high-speed rotation region. (Figure 5 dotted line). However, in the helical intake port as described above, the port shape is fixed, so as shown by the solid line in Figure 5, only a substantially constant swirl ratio can be obtained with respect to the engine rotation speed. If the shape is designed to match the low speed range, there will be excessive swirl in the high speed range (overswirl), which will worsen combustion and increase smoke in the exhaust, resulting in lower fuel efficiency. On the other hand, if matching is made in the high-speed region, there will be insufficient swirl in the low-speed region, resulting in a decrease in combustion efficiency.

In order to counter the above-mentioned disadvantages, devices have been developed that are equipped with a swirl control device that appears in and out of the vortex chamber of the helical intake port depending on the engine operating condition, as shown in Fig. 6 (for example, Showa 57
-62927 Publication, JP-A-58-2425, JP-A-Sho
58-2426, Utility Model Application Publication No. 58-81319, etc.). Furthermore, the present applicant has previously proposed a device equipped with such a swirl control device as Utility Application No. 138029/1983.

As shown in FIGS. 7 and 8, this swirl control device is provided within the terminal end of the swirl portion of the intake port 1, and is located at a position where the intake air collides with the upstream side surface and changes the streamline in the direction of the combustion chamber 5. a guide plate 3 configured to be freely rotatable between and a position substantially parallel to the intake flow;
The guide plate 3 is rotated by a rotation device 4 according to the operating state of the engine to determine its rotation position.

In such a configuration, the guide plate 3
The rotating position is determined by the rotating device 4 so as to be parallel to the intake flow as much as possible, so that a swirling flow is smoothly generated in the spiral portion 2. In other words, the horizontal component and the swirling component of the intake flow are , maximizes the characteristics of the helical intake port 1, increases swirl, improves combustion, prevents the emission of unforeseen components (smoke generation), improves fuel efficiency, and reduces ignition delay. This aims to prevent combustion noise and reduce combustion noise.

In addition, in a region where the engine requires high output such as a high-speed rotation region, the rotation device 4 is operated to set the rotation position of the guide plate 3 in a direction in which its upstream side surface faces the intake air flow. The strengthened intake air flow with a large horizontal component is converted into an intake air flow with a large component directed toward the combustion chamber 5 by the guide plate 3, thereby smoothing the intake air, that is,
It leads to the combustion chamber 5 with less loss and improves charging efficiency.

As a result, the output is increased by improving the charging efficiency without deteriorating the combustion efficiency in the high-speed rotation range where the combustion efficiency is originally high, and the amount of carbon emissions in the exhaust gas is reduced to improve fuel efficiency.

<Problems to be solved by the invention> However, the swirl control device having such a configuration has the following problems.

That is, even during high swirl, since the substantially rectangular guide plate 3 is placed in the swirling flow, the swirling flow hits the side of the guide plate 3, and the helical intake port 1
The swirl ratio decreases and the flow coefficient of the intake port 1 increases compared to the performance originally possessed by the engine.

Further, the swirl of the intake air flow is reduced by blocking a part of the swirling flow using the guide plate 3 and deflecting it to the lower combustion chamber 5. In order to make the swirl ratio sufficiently low, requires a large intake guide surface, but this is difficult due to deterioration of the flow coefficient and layout constraints of the intake port 1.
The current situation is that the swirl ratio cannot be made sufficiently low.

Therefore, in view of the conventional situation, the present invention aims to provide an intake system for an internal combustion engine that can control the swirl ratio over a wide range from high swirl to low swirl, and that can ensure the optimum swirl ratio over the entire range of engine operating conditions. do.

<Means for Solving the Problems> Therefore, the present invention provides an internal combustion engine equipped with a helical intake port in which a spiral portion is formed around the intake valve at the terminal end of the intake port. The intake air flow is caused to impinge on one side surface to deflect the streamline in the direction of the combustion chamber, and also to open a communication part that directly communicates the straight part of the intake port with the terminal end of the spiral part, so that the intake air is introduced from the communication part. and a position where the intake air flow collides with the other side surface to change the streamline toward the combustion chamber, and a position where the intake air flow is stored in a recess provided in the end of the spiral portion and closes the communication portion. The structure includes a freely movable guide plate and a guide plate rotation device that rotates the guide plate according to the engine operating state and determines the rotation position.

<Function> With such a configuration, the guide plate is not placed in the swirling flow during high swirl, and the inherent performance of the helical intake port is fully exhibited. In addition, during low swirl, a part of the swirling flow is blocked by one side of the guide plate and deflected into the combustion chamber, and at the same time, the intake air flows from the straight part of the intake port in the opposite direction to the swirling flow. Since the flow is introduced directly into the end of the swirl portion and deflected into the combustion chamber by the other side of the guide plate, it is possible to make the swirl ratio sufficiently low without deteriorating the flow coefficient.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

1 and 2, the cylinder head 6 of the engine has a helical intake port 8 communicating with each combustion chamber 7, respectively. This helical intake port 8 includes a substantially linear introduction section 9 that communicates with an intake manifold (not shown), and a spiral section 1 that is connected downstream of the introduction section 9 and communicates with the combustion chamber 7 via an intake valve 10.
Consists of 1 and. The spiral portion 11 is formed so as to surround the intake valve 10 and the upper wall 12 draws a spiral to gradually approach the combustion chamber 7, and the downstream end thereof is near the combustion chamber 7 and returns to the upstream end of the spiral portion 11. is connected to.

Here, the cylinder head 6 is formed with a screw hole 13 that penetrates from the upper wall of the terminal end of the spiral portion 11 to the outside of the cylinder head 6, and a cylindrical sleeve 14 is fitted into the screw hole 13. It is installed.

A recess 15 is formed around the screw hole 13 on the outer wall surface of the cylinder head 6, and a flange 1 formed at the head of the sleeve 14 is formed on the inner surface of the recess 15.
4a is locked.

At the terminal end of the spiral portion 11, the intake flow collides with the upstream side surface to change the streamline in the direction of the combustion chamber 7, and also connects the substantially linear introduction portion 9 of the intake port 8 and the terminal end of the spiral portion 11. A position where the communication hole 28 serving as a direct communication portion is opened and the intake air introduced from the communication hole 28 collides with the other side surface to change the flow line in the direction of the combustion chamber 7 and the end portion of the spiral portion 11. A guide plate 17 is provided which is housed in the provided recess 16 and is freely rotatable between a position where the communication hole 28 is closed. The shape of the guide plate 17 will be described later, but the guide plate 17 is integrally formed with a disk portion 19 provided at the tip of the shaft 18.

The shaft 18 is rotatably supported through the sleeve 14, and the disc portion 19 is rotatably supported within the threaded hole 13 on the distal end side of the sleeve 14. The recess 16 is formed on the peripheral wall surface of the terminal end of the spiral portion 11 so as to be continuous with the screw hole 13, and has an arcuate concave shape, and the communication hole 28 is formed in a part of the recess 16. Ru.

The guide plate 17 is formed in such a shape that it is substantially flush with the peripheral wall surface of the terminal end of the spiral portion 11 when stored in the recess 16 .

A guide plate rotation device 20 is provided which rotates the guide plate 17 formed as described above in accordance with the engine operating state and determines the rotation position thereof.

That is, a nut 21 is attached to the upper end of the shaft 18.
, one end of the lever 22 is fixed, and the lever 2
This guide plate rotating device 20 is provided at the other end of the guide plate 2.

The guide plate rotation device 20 includes a connecting bar 24 that connects the levers 22 of each cylinder in series via a ball joint 23 at the tip of the lever 22, an electromagnetic actuator 25 that moves the bar 24, and an electromagnetic actuator 25 that controls the engine rotation speed. When the speed switch 26 detects an engine rotation speed equal to or higher than a predetermined value, the electromagnetic actuator 25 is actuated to displace the connecting bar 24 and move the guide plate 17 upstream of the intake air flow via the lever 22. It is configured to include a control means 27 that rotates to a position that causes the combustion chamber to collide with the side surface and change the streamline in the direction of the combustion chamber 7.

When the engine rotation speed is in a low rotation range below a predetermined value, the speed switch 26 detects this,
The electromagnetic actuator 25 is demagnetized and the guide plate 1
7 is stored in the recess 16 and rotated to a position substantially flush with the peripheral wall surface of the terminal end of the spiral portion 11 by the elastic restoring force of a return spring (not shown).

In this case, if the speed switch 26 is configured as described above to turn on and off at a predetermined engine rotation speed, the control means 27 can be omitted, but a speed sensor that continuously detects the engine rotation speed may be omitted. In this case, the control means 27 may be configured to determine the rotational position of the guide plate 17 according to the engine rotation speed.

Therefore, according to the above configuration, when the speed switch 26 detects that the engine rotation speed is in a low rotation range below a predetermined value, the electromagnetic actuator 25 is demagnetized and the connecting bar is closed by a return spring (not shown). 24, rotate the lever 22 for each cylinder, store the guide plate 17 in the recess 16 via the shaft 18, and open the spiral part 1.
The second
(see figure).

On the other hand, the intake air introduced from the straight part 9 of the intake port 8 flows into the spiral part 11, swirls around the stem of the intake valve 10, and at the same time is guided by the upper wall surface of the spiral part 11 and is pushed down toward the combustion chamber 7. It will be done.

Here, since the guide plate 17 is substantially flush with the peripheral wall surface of the terminal end of the spiral portion 11 as described above, it does not have any factor that inhibits the intake air flow, and therefore the intake swirl flow smoothly flows into the combustion chamber. 7 and forms a strong swirl inside. As a result, the mixability of air and the fuel injected into the combustion chamber 7 is promoted, improving the air utilization rate and improving combustion, which reduces the amount of unburned components released and improves fuel efficiency. At the same time, the strong swirl increases the combustion speed, improves ignition delay, and reduces combustion noise.

Furthermore, when the engine rotational speed reaches a high-speed rotational region equal to or higher than a predetermined value, the speed switch 26 detects this and energizes the electromagnetic actuator 25 via the control means 27 to activate the connecting bar 24 and the lever 22.
The guide plate 17 is connected to the spiral portion 11 of the intake port 8 through the guide plate 17.
(See Figure 3B).

For this reason, the swirl mainstream in the spiral portion 11 is
It collides with the upstream side surface of the guide plate 17. On the other hand, the communication hole 28 between the substantially linear introduction part 9 of the intake port 8 and the terminal end of the spiral part 11 is opened, and the counter swirl flow passing through the introduction part 9 is introduced from the communication hole 28 to the terminal end of the spiral part 11. and collides with the upstream side surface of the guide plate 17. The swirl main flow and counter swirl flow that collide with both sides of the guide plate 17 have their streamlines changed in the direction of the combustion chamber 7, respectively.

In this case, the swirl mainstream is blocked by the guide plate 17 immediately before the communication hole 28 and is deflected downward. Therefore, the flow rate of the counter swirl flow increases and is introduced smoothly.

The counter swirl flow is introduced from the introduction part 9 to the terminal end of the spiral part 11 through the communication hole 28 and guided in the direction of the combustion chamber 7, at a swirling speed in the opposite direction to that of the mainstream swirl formed in the spiral part 11. Since the components are also included, the swirl ratio created at the intake port 8 can be further reduced compared to the conventional method of simply blocking the swirling flow with a guide plate, and the port flow rate coefficient can be made high.

In addition, during medium swirl, as shown in Figure 3A,
Since the communication hole 28 is opened, a part of the intake air from the introduction part 9 is introduced into the spiral part 11.
, a part of the guide plate 17 is in a protruding state, and the intake swirl flow hits the intake air from the front.
The flow is obstructed (in this case the swirl main flow has a much higher flow rate than the counter swirl flow).
Therefore, the intake air from the introduction part 9 does not have much of an effect of weakening the swirl, resulting in a medium swirl. Further, in this case, the effect of the low swirl described above gradually appears, so that the port flow rate coefficient improves slightly.

FIG. 4 is a graph comparing the port performance of the conventional example and this embodiment. In the graph, the solid line shows the characteristics of this embodiment, and the dotted line shows the characteristics of the conventional example.

In this embodiment, since there is no collision of the intake air flow with the side surface of the guide plate 17 during high swirl, there is no reduction in the swirl ratio and flow rate coefficient due to collision of the intake air flow than in the conventional example, and also, during low swirl, the intake air flow does not collide with the side surface of the guide plate 17. Due to the swirl suppressing effect of the counter-swirling intake air flow guided from 9 to the direction of the combustion chamber 7 via the terminal end of the spiral portion 11, the swirl ratio can be further reduced and the port flow coefficient can be made higher than in the conventional example.

Therefore, the flow coefficient of the intake port 8, that is, the swirl ratio can be changed over a wide range without impairing the intake efficiency of the engine, and good combustion performance can always be exhibited regardless of the operating state of the engine.

Note that the guide plate rotating device 20 is not limited to the above embodiment. The speed switch 26 or speed sensor is used to detect the engine operating state, but the engine's intake negative pressure, intake throttle valve opening, accelerator pedal opening position, diesel engine combustion injection pump control lever position, One or a combination of the combustion injection valve control pulse widths, etc. can be used. Furthermore, other power sources such as suction negative pressure, oil pressure, etc. may be used instead of the electromagnetic actuator 25.

It is already known that the rotational position of the guide plate 17 may take a value depending on the engine operating state, for example, between two positions, fully open and fully closed, as shown in FIG. 3A. As described above, this makes it possible to obtain the optimum values of swirl and charging efficiency according to the engine operating state.

<Effects of the invention> As explained above, according to the invention, in a helical intake port, a guide plate is provided at the end of the spiral part, and this guide plate directs the intake air flow to one side depending on the engine operating state. The flow line is changed in the direction of the combustion chamber by colliding with the flow line, and the communication part that directly communicates the straight part of the intake port with the terminal end of the spiral part is opened, so that the intake air flow introduced from the communication part is directed to the other side. The engine rotates between a position where the engine collides with the flow line to change the flow line in the direction of the combustion chamber, and a position where the engine is stored in a recess provided in the end of the spiral part and closes the communication part. Swirl is ensured in the low-speed rotation range, which improves combustion, prevents the emission of unburned components, improves fuel efficiency, and reduces combustion noise, while preventing over-swirl and improving intake air filling efficiency in the high-speed engine rotation range. As a result, output can be increased. In particular, since there is no collision of the intake swirl flow with the guide plate during high swirl, there is no decrease in the swirl ratio or flow coefficient due to the collision of the intake flow.
In addition, during low swirl, the swirl ratio is further reduced compared to the conventional example due to the swirl suppression effect due to the counter-swirling intake air flow that is guided from the straight part of the intake port toward the combustion chamber via the end of the spiral part, and the port flow rate is reduced. The coefficient can also be made high.

Therefore, the swirl ratio can be varied over a wide range without impairing the intake efficiency of the engine.
This has a great practical effect in that good combustion performance can always be exhibited regardless of the operating state of the engine.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of an intake system for an internal combustion engine according to the present invention, and FIG.
Cross-sectional view of the above embodiment shown by lines, FIGS. 3A and B
4 is a cross-sectional view showing other positions of the guide plate in the above embodiment, FIG. 4 is a graph showing the relationship between the swirl ratio and the port flow coefficient to explain the difference in effect between the above embodiment and the conventional example, and FIG. The figure is a graph showing the relationship between engine rotational speed and swirl ratio, FIG. 6 is a longitudinal sectional view showing an example of a conventional intake device, FIG. 7 is a longitudinal sectional view showing another example of a conventional intake device, and FIG. Figure 8 is the seventh
It is a cross-sectional view of the conventional example same as the above shown by the line in the figure. 6...Cylinder head, 7...Combustion chamber, 8...
Helical intake port, 11... spiral part, 16...
... recess, 17 ... guide plate, 20 ... guide plate rotation device, 25 ... electromagnetic actuator, 26 ... speed switch, 27 ... control means, 28 ... communication hole.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine equipped with a helical intake port in which a spiral portion is formed around the intake valve at the end of the intake port, a helical intake port is provided within the end of the spiral to cause the intake air to collide with one side surface and flow toward the combustion chamber. At the same time, the straight line of the intake port and the terminal end of the spiral part are opened, and the communication part that directly communicates with the end part of the spiral part is opened, so that the intake air flow introduced from the communication part collides with the other side surface to create a streamline in the direction of the combustion chamber. a guide plate configured to be freely rotatable between a position for changing the flow rate and a position for storing in a recess provided in a terminal end of the spiral portion and closing the communication portion; and a guide plate for placing the guide plate in an engine operating state. 1. An intake device for an internal combustion engine, comprising a guide plate rotating device that rotates in response to the rotational position of the guide plate.