JPH0415935Y2 - - 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, if we take the above-mentioned direct injection diesel engine equipped with a helical intake port as an example, as shown in Fig. 4, the swirl ratio (intake swirl speed relative to the rotational speed of the engine crankshaft) is at its optimum value. It is said that it is desirable that the amount decreases gradually as the engine moves from a low-speed rotation region to a high-speed rotation region (dotted line in Figure 4). However, since the helical intake port described above has a fixed port shape, only a substantially constant swirl ratio can be obtained with respect to the engine rotational speed, as shown by the solid line in Figure 4.
Therefore, if the port shape is designed to match the low speed range, there will be excessive swirl (overswirl) in the high speed range, which will worsen combustion and increase the swirl in the exhaust, leading to a decrease in fuel efficiency.
Excess intake resistance (pumping loss) from the swirl port deteriorates intake air filling efficiency, which hinders high output. On the other hand, if it is matched to high-speed ranges, there will be insufficient swirl in low-speed ranges, reducing combustion efficiency. There is an inconvenience.

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. 5 (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 a helical intake port is formed with a substantially linear introduction part 4 connected to the upstream end of the spiral part 3. A swirl control device 5 that appears and retracts in the direction of the valve shaft 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.

<Problems to be solved by the invention> Regarding a helical intake port equipped with a swirl control device 5 as shown in FIG.
According to the specification of No. 62927, when the tip piston portion 5a protrudes into the spiral portion 3 at high speed, the residence time of the intake air flow within the spiral portion 3 is shortened according to the amount of protrusion, and the combustion chamber is quickly filled. It is said that this improves the intake air filling efficiency.

However, in reality, the tip piston portion 5a stands against the intake air flow like a baffle plate, and greatly disturbs the intake air flow in the spiral portion 3 without imparting directionality to the intake air flow after colliding with the tip piston portion 5a. At the same time, it simply becomes an intake resistance, which obstructs the smooth flow of the intake air flow in the spiral portion 3 and causes pressure loss, reducing the intake air filling efficiency, and as a result, sufficient output cannot be obtained in the high-speed rotation region. I was afraid.

In view of the above-mentioned disadvantages of conventional intake systems, the present invention improves combustion efficiency by forming a strong swirl in the combustion chamber in low engine speed ranges, etc., while improving combustion efficiency in high engine speed ranges. The purpose is to smoothly introduce the intake air flow into the combustion chamber by giving it a direction different from the swirl, thereby improving the intake air filling efficiency without pressure loss.

<Means for solving the problem> A helical type in which a spiral portion is formed by a spiral passage provided so as to surround the intake valve shaft and the upper wall gradually approaches the combustion chamber in a spiral manner. In an internal combustion engine equipped with an intake port, it can freely rotate between a position where the intake flow provided in the volute collides with the upstream side surface and changes the streamline toward the combustion chamber, and a position approximately parallel to the intake flow. and a guide plate provided on a rotating shaft that is inclined with respect to the intake valve axis so as to approach the intake valve axis as it goes toward the combustion chamber, and the guide plate is rotated according to the engine operating state. and a guide plate rotation device for determining the rotation position of the guide plate.

<Operation> As a result, in areas where swirl is required, such as in low-speed engine rotation areas, the rotational position of the guide plate is determined by the guide plate rotation device so that the guide plate is parallel to the intake air flow as much as possible, thereby smoothing the swirl flow. In other words, the horizontal component and swirling component of the intake flow are strengthened.
The characteristics of the helical intake port are maximized to increase swirl, improve combustion, prevent the emission of unnatural components, and improve fuel efficiency. In particular, since the guide plate is installed on a rotation axis that is inclined to the intake valve axis so that it approaches the intake valve axis as it goes toward the combustion chamber, the intake air flow rotates around the valve axis through the spiral part. As it flows, it is guided by the upper wall of the passage and descends toward the combustion chamber, and the closer it gets to the combustion chamber, the closer it gets to the valve shaft.As a result, the intake flow has a small rotation radius around the valve shaft. As a result, the angular velocity of the swirl increases, and the swirl of the intake air actually introduced into the combustion chamber is sufficiently accelerated, further enhancing the above-mentioned effects such as improving combustion, preventing the emission of unburned components, and improving fuel efficiency. can be increased. 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 intake air flow with a large horizontal component is converted into an intake air flow with a large horizontal component directed toward the combustion chamber by a guide plate, and the intake air is guided smoothly into the combustion chamber with less loss.
Improves filling 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.

<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 so as to surround the intake valve 15 and gradually approach the combustion chamber 12 with the upper wall 21 drawing a straight line, and its downstream end is near the combustion chamber 12 and returns to the upstream end of the spiral portion 20. is connected to.

The terminal end of the spiral portion 20 has a guide plate 22 disposed within a plane containing the valve shaft 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, and a disc 24 provided at the upper end moves into the recess. It is free to rotate and slide with respect to the upper bottom wall of 23, or to be free to rotate through some clearance. A shaft 25 that freely rotates through the cylinder head 11 is provided at the upper end of the guide plate 22. One end of a lever 27 is fixed to the upper end of the shaft 25 with a nut 26.
A guide plate rotation device 30 is connected to the other end.

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 switch 33 detects the engine rotation speed, and when the speed switch 33 detects an engine rotation speed equal to or higher than a predetermined value, the electromagnetic actuator 32 is actuated to displace the connecting bar 31 and the lever 27 is operated.
and a control means 34 that rotates the guide plate 22 to position it within a plane containing the valve shaft of the intake valve 15 via the control means 34. When the engine rotation speed is in a low rotation range below a predetermined value, the speed switch 33 detects this, the electromagnetic actuator 32 is demagnetized, and the guide plate 22 is rotated in a circle with the valve shaft of the intake valve 15 as the central axis. It is rotated by the elastic restoring force of a return spring (not shown) so that it is located approximately within the upper surface.

In this case, if the speed switch 33 is configured as described above to turn on and off at a predetermined engine rotation speed, the control means 34 may be omitted, but it is possible to omit the control means 34, but instead of using a speed sensor that continuously detects the engine rotation speed. In some cases, the control means 34 may be configured to determine the rotational position of the guide plate 22 in accordance with the engine rotation speed.

Therefore, according to the above configuration, when the speed switch 33 detects that the engine rotation speed is in a low rotation range below a predetermined value, the electromagnetic actuator 3
2 is demagnetized, the connecting bar 31 is moved by a return spring (not shown), and the lever 27 for each cylinder is rotated so that it approaches the valve shaft of the intake valve 15 toward the combustion chamber 12. The guide plate 22 is connected to the intake valve 1 via the rotating shaft 25 inclined to
It rotates so that it is approximately located on a plane having an arcuate cross section with the valve shaft of No. 5 as the central axis. On the other hand, the intake air introduced from the introduction part 14 flows into the spiral part 20 and the intake valve 15
At the same time, it is guided by the upper wall 21 of the spiral portion 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 air flow around 5, there is no factor that obstructs the intake air flow, and therefore the intake air swirl flow A is smoothly guided into the combustion chamber 12, forming a strong swirl inside. . As a result, mixing of air and fuel injected into the combustion chamber is promoted, improving air utilization efficiency and improving combustion, which reduces emissions of unburned components and improves fuel efficiency. can.

When the engine rotational speed reaches a high rotational speed range equal to or higher than a predetermined value, the speed switch 33 detects this and energizes the electromagnetic actuator 32 via the control means 34, and controls the guide plate 22 via the connecting bar 31 and the lever 27. is brought to the position shown in FIGS. 1 and 2, that is, within a plane containing the valve shaft of the intake valve 15. Therefore, the intake air swirling flow in the spiral portion 20 is caused by the guide plate 2
The air collides with the upstream side of the intake valve 15 and is deflected toward the stem of the intake valve 15, weakening the swirling flow. Intake flow is guided by guide plate 2
However, there is a recess 23 and a disk 24 in the upper position, which prevents the upward flow of intake air and directs the entire amount downward, that is, into the combustion chamber 12. flows smoothly. 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. Efficiency can be improved, and fuel efficiency can also be improved.

In the above embodiment, the shape of the guide plate 22 is approximately rectangular, but the shape is not limited to the above embodiment, such as having a curved edge at the downstream end. For example, as shown in FIG. 3, if the guide plate 22A is made into a conical cross-sectional airfoil shape with the valve axis of the intake valve 15 as the center axis, in the low speed rotation region, the guide plate 22A is completely parallel to the intake swirl flow in the spiral portion 20. As a result, it is possible to better prevent pressure loss and turbulence in the intake flow, thereby strengthening the intake swirl sucked into the combustion chamber. The above effect is further enhanced by forming both side edges of the guide plate 22A into a smooth curved shape. In the embodiment shown in FIG. 3, when the concave surface of the guide plate 22A is positioned on the upstream side of the intake swirl flow during high-speed rotation, the guide plate 22A
Since A can reliably collect the intake air flow and direct it toward the combustion chamber 12, the intake air filling efficiency is further improved.

The axes of the guide plates 22 and 22A may be such that the lower ends of the guide plates 22 and 22A are inclined slightly toward the intake downstream side compared to the upper ends with respect to the valve axis of the intake valve 15. In this way, the intake air flow after colliding with the guide plates 22, 22A 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 charging 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. The speed switch 33 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, fuel One or a combination of these can be used, such as the control pulse width of the injector. Instead of the electromagnetic actuator 32, other power sources such as suction negative pressure,
Oil pressure or the like may also be used.

As described above, the rotational position of the guide plate 22 may be set to a value depending on the engine operating state between two positions, fully open and fully closed. This makes it possible to obtain optimum values of swirl and charging efficiency according to the engine operating conditions.

<Effects of the invention> As described above, according to the invention, the spiral portion of the helical intake port receives the intake air flow at its upstream side face and changes its streamline toward the combustion chamber, and the position is approximately parallel to the intake swirl flow. Since the guide plate rotates between the two positions depending on the engine operating condition, it is possible to ensure swirl, especially in the low engine speed range, which improves combustion, prevents the emission of unburned components, and improves fuel efficiency. At the same time, it is possible to prevent overswirl, particularly in the engine high-speed rotation region, and to increase the intake air filling efficiency and thus the output. In addition, since the guide plate is installed on a rotation axis that is inclined with respect to the intake valve axis so that it approaches the intake valve axis as it goes toward the combustion chamber, the guide plate is set at a position approximately parallel to the intake flow. In the , when the intake air flows through the spiral part swirling around the valve shaft and descends toward the combustion chamber by the upper wall of the spiral part, the closer it gets to the combustion chamber, the smaller the radius of rotation around the intake valve shaft becomes. The rotation increases the angular velocity of the rotation, and the swirl of the intake air actually introduced into the combustion chamber can be sufficiently accelerated, resulting in the above-mentioned effects such as improving combustion, preventing the emission of unburned components, and improving fuel efficiency. It can be further increased.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view taken in the direction - arrow of Fig. 2 showing one embodiment of the intake device according to the present invention, Fig. 2 is a sectional view taken in the - arrow direction of the same as above, and Fig. 3 shows another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 1, FIG. 4 is a diagram showing the relationship between engine rotational speed and swirl ratio, and FIG. 5 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, 30... Guide plate rotation device.

Claims (1)

[Scope of Claim for Utility Model Registration] A helical intake port in which a spiral portion is formed by a spiral passage provided so as to surround the intake valve shaft and gradually approach the combustion chamber as the upper wall draws a spiral. In an internal combustion engine with and a guide plate provided on a rotating shaft that is inclined with respect to the intake valve axis so as to approach the intake valve axis toward the combustion chamber, and the guide plate is rotated according to the engine operating state. An intake device for an internal combustion engine, comprising: a guide plate rotation device that determines a rotation position;