JPH0415936Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> 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. Then, the swirl portion gives a swirling flow to the intake air, and when the intake valve is opened, this swirling flow is introduced into the combustion chamber to form a large swirl in the combustion chamber,
Attempts are made to improve combustion by promoting mixing of air and fuel.

By the way, taking the above-mentioned direct injection diesel engine equipped with a helical intake port as an example, the optimum value of the swirl ratio (intake swirl speed relative to the rotational speed of the engine's crankshaft) varies from the engine's low-speed rotational range to high-speed rotational speed. It is said that it is desirable to gradually decrease the amount as the rotation region is reached. However, in the helical intake port as described above, the port shape is fixed, so as shown by the dotted line in Figure 7, only a substantially constant swirl ratio can be obtained with respect to the engine rotation speed. If the design is designed to match in the low speed range, there will be excessive swirl (overswirl) in the high speed range, which will worsen combustion and increase swirl in the exhaust, resulting in lower fuel efficiency, as well as excess intake resistance (pumping loss) at the swirl port. As a result, the intake air filling efficiency deteriorates, which becomes a factor that inhibits high output. On the other hand, if matching is made in the high speed region, swirl becomes insufficient in the low speed region, resulting in a decrease in combustion efficiency.

To counter the above-mentioned disadvantages, a device has been developed that is equipped with a swirl control device that appears in and out of the swirl chamber of the helical intake port depending on the engine operating condition, as shown in Fig. 8 (for example, in Japanese Patent Laid-Open No. 57 −
62927, JP-A-58-2425, JP-A-58-2426, and Utility Model JP-A-58-81319).

To explain this using JP-A No. 57-62927 as an example, in the cylinder head 1 of an internal combustion engine, there is a spiral portion 3 provided around the intake valve 2, and a spiral portion 3 provided around the intake valve 2.
A helical intake port is formed with a substantially linear introduction part 4 connected to the upstream end of the spiral part 3, and the intake port is connected to the upstream side of the intake valve 2 or to the intake valve 2 depending on the engine operating state within the swirling end of the swirl part 3. A swirl control device 5 that retracts and retracts toward the valve stem is provided.

The swirl control device 5 retreats from the swirl portion 3 when the engine rotates at low speed to strengthen the swirl in the combustion chamber by making the intake air flow smoothly through the swirl portion 3. However, when the engine rotates at high speed, the swirl control device 5 retreats from the swirl portion 3. A tip piston portion 5a protrudes inside to provide resistance to the intake air flow and prevent overswirl. Its swirl ratio characteristics are shown in dashed lines in FIG.

<Problems to be solved by the invention> By the way, according to the conventional swirl control device, the swirl ratio is determined by the tip piston portion 5a as described above.
Although related to the amount of protrusion, the lower limit value of the swirl ratio depends on the cross-sectional area of the tip piston portion 5a when the tip piston portion 5a is protruded to the maximum extent. On the other hand, in a direct injection diesel engine or the like which requires an appropriate swirl ratio for combustion, the required variation range of the swirl ratio is wide, and the cross-sectional area of the tip piston portion 5a must be large to meet this requirement. In other words, the swirl control device including the tip piston portion 5a becomes larger.

However, with such a large-sized swirl control device, it is extremely difficult to install it on the piston head without interfering with the intake port.
Therefore, the cross-sectional area of the tip piston portion 5a is naturally limited, and the required control width of the swirl ratio cannot be satisfied.

The present invention was made in order to eliminate the disadvantages of the conventional device, and aims to obtain a wide swirl ratio control range and to perform swirl ratio control accurately and stably.

<Means for solving the problem> A spiral part is formed by a spiral passage provided so as to surround the intake valve shaft at the end of the intake port, with the upper wall spiraling and gradually approaching the combustion chamber. In an internal combustion engine equipped with a helical intake port, the helical intake port is provided within the terminal end of the spiral portion, protrudes from the upper wall of the spiral passage toward the combustion chamber, and extends at least the upper portion of the spiral passage for a predetermined length in the axial direction of the intake valve. It is configured to be freely rotatable around an axis so that it can be placed in a position where it is closed across the entire length and causes the intake air flow to collide with the upstream surface to change the streamline toward the combustion chamber, or a position that is approximately parallel to the intake air flow. The engine is configured to include a guide plate and a guide plate rotation device that rotates the guide plate according to the engine operating state and determines the rotation position.

<Operation> As a result, the intake air flow introduced into the helical intake port determines the rotating position of the guide plate so that it is as parallel to the intake flow as possible in areas where swirl is required, such as in low engine speed rotation areas. , Smooth swirling flow is generated within the spiral part, that is, the horizontal component and swirling component of the intake flow are strengthened, and the characteristics of the helical intake port are maximized to increase swirl, improve combustion, and prevent air pollution. It prevents the emission of components (smoke generation) and improves fuel efficiency, as well as prevents ignition delay and reduces combustion noise. In addition, in areas where the engine requires high output such as high-speed rotation areas, the guide plate rotation device is operated to set the rotation position of the guide plate in a direction where its upstream side faces the intake air flow, and the volute is strengthened. The guide plate converts the intake air flow with a large horizontal component into an intake air flow with a large component directed toward the combustion chamber, thereby guiding the intake air smoothly into the combustion chamber with less loss, thereby improving charging efficiency. That is, the guide plate is projected toward the combustion chamber from the upper wall of the swirl passage, and is rotated so that the guide plate is positioned at least at the top of the swirl passage, and the intake air flowing inside the swirl passage collides with the guide plate and is directed upward and downward. However, the upward flow of intake air is blocked by the upper wall of the passage and the guide plate that closes the upper part of the passage for a predetermined length in the intake valve axis direction, so the entire amount is diverted downward, that is, to combustion. As it enters the room, it becomes a strong flow in the direction of the intake valve axis, improving filling efficiency into the combustion chamber and increasing output, while suppressing swirl in the tangential direction of the combustion chamber, preventing over-swirl and improving combustion efficiency. I can do it.
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.

In the engine's medium-speed rotation region, etc., the direction of the intake air guided by the guide plate is changed toward the intake valve shaft, and the swirl ratio is adjusted to the guide plate rotation angle, as will be described later in FIG. The swirl ratio control width is increased, and the accuracy of the swirl ratio control is improved and stabilized.

The swirl control device having such a configuration is configured such that the guide plate and its rotation axis are along the intake valve axis,
Since the guide plate is suspended from the ceiling wall of the helical intake port, it is difficult for the swirl control device to interfere with the helical intake port, and the control width of the swirl ratio can be set wide by increasing the size of the guide plate.

<Example> The present invention will be explained below based on examples.

1 and 2 show an embodiment of the present invention, in which each combustion chamber 1 is provided in a cylinder head 11 of an engine.
It has a helical intake port 13 that communicates with each of the two ports. The helical intake port 13 has a substantially linear introduction portion 14 that communicates with an intake manifold (not shown).
and a spiral portion 20 connected downstream thereof and communicating with the combustion chamber 12 via the intake valve 15.
The spiral portion 20 is formed by a spiral passage provided so that the upper wall 21 spirals around the intake valve shaft and gradually approaches the combustion chamber 12, and the downstream end of the spiral passage forms a spiral again near the combustion chamber 12. The upstream end of section 20 is connected in communication.

The terminal end of the spiral portion 20 has a guide plate 22 disposed within a plane that includes the axis of the intake valve 15 . The guide plate 22 has a substantially rectangular shape, and is freely rotatable within a recess 23 provided in the cylinder head 11 on the upper wall of the terminal end of the spiral portion 20, with a disk 24 provided at the upper end moving into the recess 23. It is free to rotate and slide with respect to the upper bottom wall, or to be able to rotate freely through some clearance. A rotating shaft 25 is provided at the upper end of the guide plate 22 along the intake valve shaft and freely passing through the cylinder head 11. One end of a lever 27 is fixed to the upper end of the rotating shaft 25 with a nut 26. A guide plate rotation device 30 is connected to the other end of the lever 27.

The guide plate rotating device 30 connects the lever 27 for each cylinder via a ball joint 28 at the tip of the lever 27.
a connecting bar 31 that connects the bar 31 in series; an electromagnetic actuator 32 that moves the bar 31;
A speed sensor 33 detects the engine rotation speed, and an electromagnetic actuator 32 is actuated according to the engine rotation speed detected by the speed sensor 33 to displace the connecting bar 31 and the guide plate 22 is moved via the lever 27.
and a control means 34 for rotating the.

By the way, to explain with reference to FIG. 4, the guide plate 22
Assume that the rotational position of is set at +θ or -θ with the center being a position A-A that is substantially parallel to the intake swirl flow F in the spiral portion 20. Here, the +θ position is the position where the intake swirl flow hits the guide plate 22 and is guided in a direction approaching the axis of the intake valve 15, and -θ
The position is a position where the guided intake swirl flow is guided in a direction away from the axis of the intake valve 15.

Regarding the rotational position of the guide plate in these two directions,
FIG. 6 was obtained as a result of testing the relationship between the rotation angle θ of the guide plate 22 and the swirl ratio. According to this, when the guide plate 22 is rotated in the -θ direction, the swirl ratio tends to change suddenly from the maximum to the minimum around -30 degrees.
It has been found that controlling the swirl ratio by controlling the rotation angle -θ is extremely difficult. On the other hand, when the guide plate 22 is rotated in the +θ direction, the swirl ratio is relatively smooth and continuous over a wide range of about 0° to 90°.

Therefore, from the viewpoint of securing a control width of the swirl ratio, smoothing the change in swirl ratio with respect to the guide plate rotation angle, and improving the accuracy of swirl ratio control corresponding to guide plate rotation angle control, the guide plate 22 is The rotation range is preferably in the +θ direction, and the maximum restricted range is from a position approximately parallel to the intake flow to approximately perpendicular to the intake flow, as shown in Figure 3, so that the guided intake flow is guided toward the combustion chamber. up to the position.

Therefore, according to the above configuration, the speed sensor 3 detects that the engine rotation speed is in the low speed rotation region below the predetermined value.
3 is detected, the electromagnetic actuator 32
to move the connecting bar 31, rotate the lever 27 for each cylinder, and use the rotation shaft 25 to
The guide plate 22 is rotated so as to be located approximately on the inner surface of a cone or cylinder whose center axis is the axis of the intake valve 15, as shown in FIG. On the other hand, the intake air introduced from the introduction part 14 flows into the spiral part 20, swirls around the axis of the intake valve 15, and is simultaneously guided by the upper wall 21 of the spiral part 20 and pushed down toward the combustion chamber 12.

Here, the guide plate 22 is connected to the intake valve 1 as described above.
Since it is approximately parallel to the intake flow around the axis 5, there is no factor that obstructs the intake flow, and therefore the intake swirl flow F is smoothly guided into the combustion chamber 12, creating a strong swirl inside. Form. As a result, the mixing of air and the fuel injected into the combustion chamber is promoted, improving the air utilization rate and improving combustion, which reduces the amount of unburned components emitted and improves fuel efficiency. The swirl increases the combustion speed, improves ignition delay, and reduces combustion noise.

Further, when the engine rotation speed reaches a high rotation speed range, the speed sensor 33 detects this and operates the electromagnetic actuator 32 via the control means 34, causing the guide plate 2
is brought to the fifth illustrated position, that is, within a plane containing the axis of the intake valve 15. Therefore, the intake swirling flow within the swirl portion 20 collides with the upstream side surface of the guide plate 22 at a substantially right angle, and is deflected in the axial direction of the intake valve 15, thereby weakening the swirling flow. The intake airflow collides with the guide plate 22 and attempts to separate above and below, but there are recesses 23 and disks 24 at the upper position, which prevent the upward flow of intake air and direct the entire amount downward, that is, into combustion. It flows smoothly into the chamber 12. As a result, the intake air has a strong flow in the axial direction of the intake valve 15 while minimizing the pressure loss caused by changing the flow path, increasing the charging efficiency and improving the output.Furthermore, it prevents overswirl and combustion. It is possible to improve fuel efficiency by improving efficiency and suppressing the generation of smoke and the like.

In a medium speed rotation region such as when the engine is under partial load, the guide plate 22 assumes a position as shown in FIG. 4, as described above. Therefore, the intake swirl flow F collides with the upper surface of the guide plate 22, is guided toward the axis of the intake valve 15, and is then sucked into the combustion chamber 12. Here, as the rotation angle +θ of the guide plate 22 increases in value, the swirl ratio gradually decreases as shown in FIG. 6 (or the solid line in FIG. 7). Therefore, the guide plate 22
The swirl ratio can be reduced on average until the rotation angle reaches 0° to 90°, that is, from FIGS. 3 to 5.

As is clear from this, the swirl ratio control width is as large as the guide plate rotation angle of approximately 90 degrees, and the rotation shaft 25 of the guide plate does not interfere with the intake port 13 due to its small diameter. Further, since the rate of change of the swirl ratio changes smoothly with respect to the rotation angle θ of the guide plate 22, the resolution of the swirl ratio with respect to the rotation angle of the guide plate can be obtained stably and substantially uniformly, and control accuracy is improved.

In addition, in the intermediate region, the swirl ratio changes smoothly with respect to the rotation angle of the guide plate, so the entire rotation range can be effectively used for swirl ratio control, which increases the swirl ratio control width and controls the swirl ratio. can be performed stably and accurately, which in turn improves engine output and fuel efficiency. Despite having such features, since the guide plate and its rotation axis are aligned, the degree of interference between the swirl ratio control means and the helical intake port can be reduced, which is advantageous in terms of layout.

In the above embodiment, the guide plate 22 is rotated until the rotation angle is 90 degrees.
It is not necessarily necessary to rotate the valve to this extent, and it is sufficient to set the valve so that at least the upper part of the spiral passage can be closed over a predetermined length in the axial direction of the intake valve.

Further, in the above embodiment, the guide plate 22 has a substantially rectangular shape, but the shape is not limited to the above embodiment, such as having a curved edge at the downstream end. For example, if the guide plate 22 is formed into an arcuate airfoil shape with the axis of the intake valve 15 as the central axis, the spiral portion 2
Since the intake air swirl flow is completely parallel to the intake air swirl flow in the combustion chamber, it is possible to better prevent pressure loss and turbulence in the intake air flow, thereby strengthening the intake air swirl sucked into the combustion chamber. The above effect is further enhanced by forming both side edges of the guide plate 22 into smooth curved shapes. In addition, when the concave surface of the guide plate 22 is located on the upstream side of the intake air swirl flow during high-speed rotation, the guide plate 22 can reliably collect the intake air flow and direct it toward the combustion chamber 12, thereby filling the intake air. Efficiency is further improved.

The lower part of the guide plate 22 and the rotating shaft 25 may be inclined slightly toward the intake downstream side compared to the upper part with respect to the axis of the intake valve 15. In this way, the intake air flow after colliding with the guide plate 22 is introduced into the combustion chamber 12 more smoothly without pressure loss, and large turbulence of the intake air flow can be prevented, so that the filling efficiency is further improved. Even if this is done, there is no change in the effect of blocking the intake swirl flow.

It goes without saying that the guide plate rotating device is not limited to the above embodiment. A speed sensor was used to detect the engine operating status, but the engine suction negative pressure,
One or a combination of the intake throttle valve opening, the accelerator pedal opening position, the control lever position of the combustion injection pump of the diesel engine, the control pulse width of the fuel injection valve, etc. can be used. Other power sources such as suction negative pressure, oil pressure, etc. may be used instead of the electromagnetic actuator 32.

<Effects of the invention> As described above, according to the invention, in engine operating conditions where swirl is required, the upstream side of the guide plate protruding from the swirl passage is positioned parallel to the intake air flow, thereby reducing the flow in the tangential direction of the combustion chamber. A strong swirl can be generated along the lines to improve combustion, prevent the emission of unburned components, and improve fuel efficiency. On the other hand, in an engine operating state where swirl is not required, the guide plate collides with the guide plate so as to block at least the upper part of the swirl passage over a predetermined length in the direction of the intake valve axis, forcing the swirl into the combustion chamber. Changes streamlines, reduces swirl, increases intake air filling efficiency,
As a result, combustion efficiency and fuel efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view taken along the - arrow in Fig. 2 showing an embodiment of the intake device according to the present invention, Fig. 2 is a sectional view taken in the - arrow direction shown in the above, and Figs. This is a diagram corresponding to Figure 2 that explains the operating state. Figure 3 shows the engine in a low speed state, Figure 4 shows an intermediate state, Figure 5 shows a high speed state, and Figure 6 shows the relationship between the rotation angle of the guide plate and the swirl ratio. FIG. 7 is a graph showing the relationship between engine rotational speed and swirl ratio, and FIG. 8 is a diagram showing a conventional intake system for an internal combustion engine. 11... Cylinder head, 12... Combustion chamber, 1
3...Helical intake port, 14...Introduction part,
15... Intake valve, 20... Spiral section, 22... Guide plate, 25... Rotating shaft, 30... Guide plate rotating device,
+θ……Guide plate rotation angle.

Claims (1)

[Scope of Claim for Utility Model Registration] A spiral portion is formed by a spiral passage provided so as to surround the intake valve shaft at the end of the intake port, with the upper wall drawing a spiral pattern and gradually approaching the combustion chamber. In an internal combustion engine equipped with a helical intake port, the helical intake port is provided within the terminal end of the spiral portion, protrudes from the upper wall of the spiral passage toward the combustion chamber, and extends at least the upper portion of the spiral passage to a predetermined length in the axial direction of the intake valve. The guide is configured to be freely rotatable around an axis so that it can be placed in a position where it crosses over and closes, causing the intake flow to collide with the upstream surface to change the streamline toward the combustion chamber, or a position approximately parallel to the intake flow. An intake system for an internal combustion engine, comprising: a plate; and a guide plate rotation device that rotates the guide plate according to engine operating conditions and determines the rotation position of the guide plate.