JPH077547Y2 - Intake port structure of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an intake port structure of an internal combustion engine in which three intake valves are provided for one cylinder.

[Conventional technology]

In order to improve the output performance of the engine, a configuration in which three intake valves are provided for one cylinder is conventionally known (Japanese Patent Laid-Open No. 60-216013). The intake port of such an engine has one inlet and three communicating ports.
And two outlet portions, and the ratio of the sectional area of the inlet portion to the sectional area of the outlet portion is relatively large. Also,
It is generally known that the diameter of the intake port is reduced to a small value to maintain a high intake flow velocity even during low speed operation of the engine, thereby producing an inertial intake effect and improving engine output during low speed operation.

[Problems to be solved by the device]

However, if the diameter of the intake port is reduced in order to improve the inertial intake effect during low speed operation as described above, the resistance of the intake port increases and the efficiency of charging intake air during medium and high speed operation decreases. However, there is a problem that the engine output becomes insufficient during medium to high speed operation.

That is, it is preferable that the diameter of the intake port is made as small as possible in consideration of the inertial intake effect during low speed operation, but in consideration of the increase in intake resistance during medium and high speed operation, the port diameter cannot be reduced infinitely. On the other hand, the intake resistance during mid-high speed operation greatly depends not only on the diameter of the intake port but also on the shape of the port, so if the shape of the intake port is set appropriately, the intake port diameter will be similar. However, the intake resistance can be greatly reduced.

In view of the above, the present invention reduces the intake resistance when the intake port diameter is narrowed to increase the inertial intake effect during low speed operation by appropriately setting the shape of the intake port, and insufficient output during middle and high speed operation. It is an object of the present invention to provide an intake port structure capable of preventing the occurrence of the above.

[Means for Solving the Problems]

The present invention has one inlet part and three outlet parts communicating with the inlet part, and these three outlet parts have circular cross sections with substantially the same radius, and the inlet part has an oval cross section. An inlet port structure of an internal combustion engine, wherein the outlet portion is disposed substantially along a direction of an elliptical major axis of the inlet portion, and the inlet portion has a major axis (a) and a minor axis (b). It is characterized in that it can be narrowed down within the range that satisfies the following formula.

a ≧ x−2y b ≧ 2y where x is the distance between the centers of the two outlets located on both sides, and y is the radius of the outlets.

[Action]

When the intake port diameter is narrowed to enhance the inertial intake effect at low speed, the shape of the intake port inlet is set as described above, so that the increase in intake resistance during medium-high speed operation is suppressed.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an embodiment of the present invention. In this figure, the cylinder head 10 is formed with an intake port 11 extending obliquely with respect to the axis I of the cylinder, and at the terminal end of the intake port 11 with respect to the axis J of the upstream side portion of the intake port 11. A throat portion 12 having an axis K that is slightly inclined is formed. An annular valve seat 13 is fitted in the throat portion 12.

1 (A) shows the plan shape of the intake port 11, and FIG. 1 (B) shows the front shape of the inlet portion 14 of the intake port 11.

In FIGS. 1 (A) and 1 (B), the intake port 11 includes one inlet portion 14 and three outlet portions 1 communicating with the inlet portion 14.
5,16,17 and these inlet part 14 and outlet part 15,16,17
Communicate with each other via a passage 18. Three outlets 15,1
6 and 17 have circular cross sections with substantially the same radius,
Further, the inlet portion 14 has an oval cross section, and is formed as small as possible within a range satisfying the expressions (1) and (2) described later. The outlet portions 15, 16 and 17 are arranged substantially along the direction of the major axis of the elliptical shape of the inlet portion 14, and more precisely, along the circumferential direction of the cylinder. The length of the major axis of the ellipse of the inlet portion 14 is a, the length of the minor diameter is b, the center distance between the two outlet portions 15 and 17 located on both sides is x, and the radius of each outlet portion 15, 16, 17 Is y, the major axis a and the minor axis b of the inlet portion 14 satisfy the following expressions. That is, a ≧ x−2y (1) b ≧ 2y (2) In the present embodiment, the lateral diameter of the inlet portion 14, that is, the major axis a is
It is not shorter than the length obtained by subtracting the radius of the outlet from the axial distance between the outlets 15 and 17 on both sides. The reason why the major axis a is determined in this way is to make it easy to guide the air flowing in from the inlet portion 14 to the outlet portions 15 and 17 on both sides. Further, the longitudinal diameter of the inlet portion 14, that is, the minor axis b is not shorter than the diameter of the outlet portions 15, 16 and 17.
The reason why the minor axis b is determined in this way is to prevent the flow velocity of the intake air from decreasing in the intake port 11 as it flows from the upstream side to the downstream side, and to secure the dynamic pressure. Even if the intake port is throttled to increase the inertial intake effect during low speed operation by setting the inlet major axis a and the minor axis b to be equal to or greater than the above-mentioned minimum values, the intake resistance is extremely increased during medium and high speed operation. It is reduced, and it is possible to prevent the output of the engine from being insufficient at the time of medium and high speed operation.

Also, the left end 14a of the inlet 14 and the right end 15a of the left outlet 15
The straight line connecting to and L is the right end portion 14b of the entrance portion 14 and the right exit portion 1
If the straight line connecting the left end 17a of 7 is M, the intake port 11
The angle α between the left inner wall surface 11a and the straight line L and the angle β between the right inner wall surface 11b of the intake port 11 and the straight line M are each 5 °. These angles α and β need only be 10 ° or less, which prevents the intake airflow from separating from the wall surfaces 11a and 11b at the curved portions.

FIG. 3 is a cross-sectional area of the intake port inlet portion 14 and the intake port 11
Shows the relationship with the static intake air flow rate passing through, that is, the relationship between the port cross-sectional area and the intake air amount during high-speed operation at a certain rotation speed. In this figure, the solid line S indicates the intake air amount when the intake port inlet shape is set as in the above embodiment. As shown in Fig. 3, when the intake port cross-sectional area is reduced from A ₁ (when the intake port is not throttled at all) to enhance the inertial intake effect,
By setting the intake port inlet shape as in the above embodiment, the intake air amount hardly changes even if the port cross-sectional area is reduced to a certain value (for example, the area shown by A ₂ in FIG. 3). That is, by setting the inlet port inlet shape as in the above embodiment, the port cross-sectional area can be reduced from A ₁ to A ₂ with little increase in intake resistance during medium-high speed operation.

As a result, it is possible to improve the inertial intake effect by narrowing the intake port as compared with the conventional one while securing the same intake air amount during medium-high speed operation. In this embodiment, even when the port cross-sectional area is A ₂ , the intake air amount is set to a value Ga ₂ or more that can obtain a sufficient engine output during medium-high speed operation.

[Effect of device]

According to the present invention, by setting the intake port inlet shape as described above, when the intake port is narrowed down to improve the inertial intake effect during low speed operation, the increase in intake resistance during medium and high speed operation is suppressed, It is possible to prevent an engine output shortage from occurring.

[Brief description of drawings]

FIG. 1 (A) is a plan view showing an intake port of an embodiment of the present invention, FIG. 1 (B) is a front view of an inlet portion of the intake port of FIG. 1 (A), and FIG. 2 is the present invention. FIG. 3 is a graph showing the relationship between the cross-sectional area of the inlet portion of the intake port and the intake air amount during medium-high speed operation. 11 …… Intake port, 14 …… Inlet, 15,16,17 …… Outlet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takayoshi Nakagawa, Toyota Motor Co., Ltd., 1 Toyota Town, Toyota City, Aichi Prefecture (72) Inventor, Go Yamayama, 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. An inlet section and three outlet sections communicating with the inlet section, the three outlet sections having circular cross sections having substantially the same radius, and the inlet section having an oval cross section. And the outlet is arranged substantially along the direction of the major axis of the ellipse of the inlet, and the inlet has a major axis (a) and a minor axis (b) within a range satisfying the following equation. An intake port structure for an internal combustion engine characterized by being throttled. a ≧ x−2y b ≧ 2y where x is the distance between the centers of the two outlets located on both sides, and y is the radius of the outlets.