JPH07224718A - 3 intake valve engine intake port structure - Google Patents

Abstract

(57) [Abstract] [Purpose] Improve the output by increasing the inertial intake effect during low speed operation while securing the intake air amount during middle and high speed operation of the engine. An intake port 5 of a three-intake valve engine is provided with one inlet portion 11 and three outlet portions 12, 1 which are in communication with the inlet portion 11 and have substantially the same cross-sectional areas.
3, 14 and. When the major axis of the inlet portion 11 is a, the center-to-center distance between the outlet portions 12 and 14 located on both sides is w, and the axial diameter of the intake valve disposed at the outlet portions 12 and 14 is d, a ≧ w−d In the intake port 5 having the above relationship, a partition wall 16 is formed between the outlet portions 12, 13, 14 which are adjacent to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake port of an internal combustion engine, and more particularly to an intake port structure for an engine in which three intake valves are provided for each cylinder in order to improve intake efficiency.

[0002]

2. Description of the Related Art Conventionally, this type of intake port structure has one inlet portion and three outlet portions communicating with the inlet portion to improve the output torque during medium-high speed operation. The ratio of the sectional area of the inlet portion to the sectional area of the outlet portion is relatively large. However, if the intake port inlet portion is formed thick, the inertial intake effect is reduced and the output torque during low speed operation becomes insufficient. Therefore, a Siamese type intake port structure that improves the inertial intake efficiency and improves the engine efficiency during low speed operation while maintaining the output torque during medium to high speed operation has been developed by the applicant of the present application.
It is proposed in Japanese Patent No. 4427.

As shown in FIG. 5 (b), in this intake port structure, the three outlets 52a, 52b, 52c have a circular cross section with substantially the same radius, and there is no partition between the outlets. Siamese type. Also, the entrance 5
1 has an oval cross section, and has the outlet portions 52a, 52b, 5
2c is disposed substantially along the elliptical major axis direction of the inlet portion 51. And three outlet parts 52a, 52b, 5
If the center-to-center distance between the two outlets 52a, 52c located on both sides of 2c is x and the radius of the outlets 52a, 52b, 52c is y, the major axis z1 and minor axis z2 of the inlet 51 are expressed by the following equations. It is specified in the shape to be.

Z1 ≧ x−2y z2 ≧ 2y Therefore, according to the above-mentioned conventional technique, the shape of the inlet portion 51 is defined by the above equation, so that the cross-sectional area of the port inlet portion 51 is reduced by inertial intake during low speed operation. By adopting the Siamese type in which the size is high and the partition wall is not provided between the outlets, it is possible to secure the intake air amount during the medium-high speed operation. Therefore, from the above, the output can be improved from low speed to high speed operation.

[0005]

However, in the above-mentioned prior art, when a higher intake air amount is required, it is necessary to increase the cross-sectional area of the inlet portion in order to increase the inflow air. However, if the cross-sectional area of the inlet part is enlarged, the flow velocity cannot be maintained from the inlet part to the outlet part, the filling efficiency is reduced, and the intake distribution to each port becomes non-uniform, and desired performance cannot be achieved. There was a problem.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to increase the intake air amount at the time of medium-high speed operation while maintaining the inertial intake efficiency at the time of low-speed operation so as to increase from low speed to high speed. An object of the present invention is to provide an intake port structure of a three-intake valve engine capable of improving output over driving.

[0007]

In order to achieve the above object, in the first invention, a three-intake valve having one inlet portion and three outlet portions having substantially the same cross-sectional areas are formed. In the intake port structure of the engine, where a is the major axis of the inlet, w is the distance between the centers of the outlets located on both sides, and d is the axial diameter of the intake valve disposed at the outlet, a ≧
The gist of the invention is that a partition wall is formed between the outlet portions adjacent to each other in the intake port having the relationship of wd and the outlet portions are concentric.

According to the second aspect of the invention, the intake port has a central second port portion whose outlet portion is divided by a partition wall and first and third inlet portions arranged on both sides of the second port portion. And a port portion, and the second port portion and the other port portions are arranged so that the axial center of the second port portion and the axial center of the other port portion intersect with each other.
In the intake port structure of an intake valve engine, the end wall of the partition wall has an intersection A where the upper and lower lines of the second port section intersect with the upper and lower lines of the first and third port sections when viewed from the side. , B and a partition wall end face having a predetermined radius of curvature that is formed between the port portions in a plan view and that corresponds to the penetration line.

[0009]

According to the structure of the first aspect of the invention, in the intake stroke of the engine, air is introduced into the intake port and flows from the inlet portion to the outlet portion. By providing the partition wall that divides the outlet portion, the passage area is reduced to be equivalent to each port. Since the major axis a of the inlet portion is equal to or greater than the value obtained by subtracting the axial diameter d of the intake valve from the center-to-center distance w between the two outer outlet portions, the partition wall does not have ventilation resistance, but rather increases the intake air flow velocity. . Furthermore, this partition allows smooth distribution of ventilation to each of the outlet portions of the port.

On the other hand, by increasing the inlet cross-sectional area, it is possible to increase the amount of intake air during medium-high speed operation. According to the configuration of the second invention, the end wall of the partition wall is
An intersection A where the upper and lower lines of the second port intersect with the upper and lower lines of the first and third port parts, respectively, when viewed from the side.
It is formed along a line connecting B and the partition wall end face having a predetermined radius of curvature that is formed between the port portions in a plan view and that corresponds to the penetration line. Therefore, the crotch portion is formed smoothly according to the left and right opening and the bottom opening of the intake port, and the resistance of the partition wall to the air flowing through the intake port becomes extremely small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the intake port structure of a 3-intake valve engine according to the present invention is embodied in a 4-cylinder engine will be described in detail below with reference to the drawings.

As shown in FIG. 1, a cylinder block 1 of the engine includes first to fourth cylinders (first cylinder # in FIG. 1).
(Only one is shown) are arranged in parallel. Piston 2 in each cylinder
Are respectively reciprocally movable in the vertical direction, and each piston 2 is connected to a crankshaft (not shown) via a connecting rod 3. Combustion chambers 4 are formed above the pistons 2, and three intake ports 5 on one side and two exhaust ports 6 on the other side are opened on the upper wall of each combustion chamber 4. The intake port 5 extends obliquely with respect to the axis of the cylinder, and a throat portion 7 is formed at the terminal end portion. An annular valve seat 8 is fitted in the throat portion 7. The cylinder head 1 of the engine is provided with three intake valves 9 and two exhaust valves 10 for each cylinder, and the intake port 5 and the exhaust port 6 are opened and closed by these intake and exhaust valves 9 and 10. To be done.

As shown in FIG. 2, the intake port 5 is
It has one inlet part 11 and three outlet parts 12, 13, 14 and the inlet part 11 is connected to the outlet parts 12, 13,
It is in communication with 14. The inlet part 11 is formed in an oval cross section, and the outlet parts 12, 13, 14 are arranged substantially along the major axis direction of the oval shape of the inlet part 11. Specifically, they are arranged along the circumferential direction of the cylinder. Here, intake port 5
When the major axis a of the elliptical inlet portion 11, the center-to-center distance w of the outlet portions 12 and 14 located on both sides, and the axial diameter of the intake valve 9 are d, the following relationship holds.

A ≧ wd In the above equation, the major axis a of the inlet portion 11 and the outlet portions 12, 1
The difference between the center-to-center distance w of 4 and the shaft diameter d of the intake valve 9 represents the opening degree of the intake port 5 from the inlet to the outlet.

The throat portion 7 of the intake port 5 is provided with a partition wall 16 that divides the three outlet portions 12, 13, and 14. As a result, the intake port 5 is divided into three port portions 17, 18, and 19. Also, the port entrance 1
The change in the cross-sectional area of the passage 15 from 1 to the outlet portions 12, 13, 14 is formed so as to change smoothly over the entire length of each port portion 17, 18, 19. Therefore, the second port portion 18 and the first and third port portions 17, 19
In the intersection line S where and intersect, the partition wall end surface is formed so that the radius R1 is as small as possible in manufacturing.

As shown in FIG. 3, the upper and lower surfaces of the central second port portion 18 and the first and third port portions 17 and 19 on both sides in the figure intersect at points A and B, respectively, and Port section 18
And the axis of the first and third port portions 17, 19 intersect at an angle α. Therefore, as shown in FIG. 4, a concave portion 18a is formed at the center of the cross section of the intake port 5, and the concave portion 18a gradually increases in depth toward the downstream side of the intake port 5. On the other hand, the end wall viewed from the side surface of the partition wall 16 is formed on a line connecting the points A and B and the partition wall surface formed corresponding to the penetration line S. Therefore, the crotch portion is formed smoothly according to the left and right opening degree and the vertical opening degree of the intake port 5, and the resistance of the partition wall to the air flowing through the intake port becomes extremely small. Further, as shown in FIG. 4, the joint portion between the second port portion 18 and the first and third port portions 17 and 19 on both sides is formed in an arc R2 shape.

Next, the operation and effect of the intake port structure configured as described above will be described. In the intake stroke of the engine, the piston 2 descends in the cylinder # 1 to introduce air into the intake port 5. At the time of intake, the flow velocity distribution of the intake air flowing through the passage 15 on the upstream side of the intake port 5 is maximized in the central portion farther from the wall of the passage 15 as shown by the arrow in FIG. For example,
Compared with the Siamese type shown in (b),
In the intake port structure (a) of the present embodiment, the inlet width is formed wider, so that the flow velocity of air becomes low. However, by providing the partition wall 16 that divides the outlet portion, the passage area can be reduced to be equivalent to the port portions 17, 18, and 19, and the flow velocity at the port outlet portions 12, 13, and 14 can be increased.

Usually, when the opening toward the outlets 12, 13, 14 is large, that is, when the condition of a <wd is satisfied, the provision of the partition 16 becomes a resistance. FIG. 6 shows the relationship between the length l of the partition wall 16 and the static intake air flow rate when a <wd. When the length l of the partition wall 16 increases, the flow rate f1 of the central second port portion 18 increases, but the flow rate f of the first and third port portions 17 and 19 on both sides increases.
2 decreases, and the flow rate f3 of the intake port 5 as a whole decreases with an increase in the partition wall length 1. However, in this embodiment, the partition 16 does not have ventilation resistance because it is formed under the condition of a ≧ wd, and rather, the flow velocity can be increased and the inertial intake effect can be enhanced. Further, the partition wall 16 allows the outlet portion 12 of the intake port 5,
The ventilation distribution to each of 13 and 14 can be performed smoothly.

FIG. 7 shows the cross-sectional area of the inlet portion 11 and the static intake air flow rate of the intake port 5 when the partition wall is provided f4 and when the partition wall is not provided f5 under the condition of a ≧ wd. Shows the relationship. As described above, it can be seen that when the partition wall 16 is provided, the intake air flow rate increases when the cross-sectional area of the inlet portion 11 is large, that is, in the region where the influence of the decrease in flow velocity is significant.

In FIG. 8, when the partition wall end surface K (see FIG. 3) is set to the downstream side of the intake port 5 with respect to the partition wall end surface J in this embodiment, that is, when the partition wall length is shortened f6
The cross-sectional area of the port is shown. It can be seen that when the length of the partition wall is shortened, the passage area is sharply reduced in the vicinity of the outlet portions 12, 13, 14 as compared with the case of this embodiment f7. FIG. 9 shows a flow rate comparison when the length of the partition wall is shortened in the relationship between the static intake air flow rate of the entire intake port 5 and the valve lift amount of the intake valve. Compared with this Example f8 shown by the solid line,
It can be seen that when the partition wall end face J shown by the dotted line is set on the downstream side of the port and the partition wall end face K is located, the flow rate of f9 decreases. This is because the passage area is rapidly reduced in the vicinity of the outlets 12, 13 and 14, so that the actual intake air amount cannot be secured even if the inflow amount from the inlet 11 is equal.

As described in detail above, the relationship between the major axis length a of the elliptical inlet portion, the center-to-center distance w of the outlet portions 12 and 14 located on both sides, and the valve shaft diameter d is a ≧ w−d. Since the partition wall 16 is provided in the intake port 5 of the above, the cross-sectional area of the inlet portion 11 is increased to increase the intake air amount, and the outlet portion 1 is
The air velocities of 2, 13, and 14 can be kept high. Further, since the intake port 5 is divided by the partition wall 16, the intake and injected fuels can be evenly distributed to the respective port portions 17, 18 and 19, and good combustion can be obtained. Furthermore, since the upper and lower surfaces of the intake port 5 are connected by the partition wall 16, the rigidity of the cylinder head can be increased.

The present invention is not limited to the above-described embodiment, but can be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the invention is applied to a 4-cylinder engine.
Applies to 6-cylinder engines or other engines.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (I) The predetermined radius of curvature has a minimum curvature.
Intake port structure described in. With this configuration, the resistance due to the partition wall can be made extremely small.

Here, the engine includes a gasoline engine and a diesel engine. Further, the three-intake valve engine is an engine in which three intake valves are provided per cylinder, and the valve opening area and port area can be widened relative to the bore diameter to improve intake efficiency.

[0025]

As described above in detail, according to the first aspect of the present invention, while increasing the intake air amount during the middle and high speed operation,
It has an excellent effect that it is possible to provide an intake port structure of a three-intake valve engine that maintains the inertial intake efficiency during low speed operation and improves the output from low speed to high speed operation.

According to the second aspect of the invention, the end wall seen from the side surface of the partition wall is formed on a line connecting the points A and B and the partition wall surface formed corresponding to the penetration line S. Therefore, there is an excellent effect that the resistance of the partition wall to the air flowing through the intake port becomes extremely small.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an intake port of a three-intake valve engine according to an embodiment of the present invention.

FIG. 2 is a plan view showing the intake port structure of FIG.

3 is a front view showing the intake port structure of FIG. 2. FIG.

FIG. 4 is a cross-sectional view showing the intake port structure of FIG.

FIG. 5 is a diagram modeling the intake flow velocity distribution in the intake port, wherein (a) is an intake port of the present invention and (b) is an explanatory view showing a Siamese type intake port.

FIG. 6 is a characteristic diagram showing a relationship between a partition wall length l of an intake port and a static intake air flow rate.

FIG. 7 is a characteristic diagram showing a relationship between an inlet cross-sectional area of an intake port and a static intake air flow rate.

FIG. 8 is a characteristic diagram showing a relationship between a position of an intake port and a port cross-sectional area.

FIG. 9 is a characteristic diagram showing a relationship between a valve lift amount and a static intake air flow rate.

[Explanation of symbols]

5 ... intake port, 9 ... intake valve, 11 ... inlet part, 1
2, 13, 14 ... Exit part, 16 ... Partition wall.

Claims (2)

[Claims] 1. An intake port structure of a three-intake-valve engine having one inlet part and three outlet parts formed to have substantially the same cross-sectional area, and the major axis of the inlet part is located at a and both sides are located. When the distance between the centers of the outlets is w and the axial diameter of the intake valve arranged at the outlets is d, a partition wall is formed between the outlets adjacent to each other in the intake ports having a relationship of a ≧ w−d. An intake port structure for a three-intake valve engine, characterized in that the outlets are concentric. 2. The intake port comprises a central second port part whose outlet part is divided by a partition wall, and first and third port parts arranged on both sides of the second port part. In the intake port structure of a three-intake-valve engine in which the axial center of the second port portion and the axial center of the other port portion are arranged so as to intersect each other when viewed from the side surface, the end wall of the partition wall has a second end when viewed from the side surface. Both upper and lower lines of the port portion are formed corresponding to intersections A and B, which intersect with the upper and lower lines of the first and third port portions, respectively, and between the port portions when seen in a plan view, corresponding to interpenetrating lines. The intake port structure for a three-intake valve engine according to claim 1, wherein the intake port structure is formed along a line connecting the partition wall end face having a predetermined radius of curvature.