JPH0366496B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an air intake system for an engine whose intake passage is composed of a main intake passage and an auxiliary intake passage, each of which performs intake suitable for high-load operation and low-load operation. Regarding equipment.

(Prior art) In engines, combustibility generally tends to decrease during low-load operation. A swirl of flowing intake air is generated. On the other hand, generating swirl in this manner is disadvantageous in reducing intake resistance and improving intake air filling efficiency during high-load operation, so there is a demand for suppressing the generation of swirl.

Therefore, the intake passage is composed of a main intake passage and an auxiliary intake passage, one of which is for high load use.
The other side is an intake passage for low-load use.The main intake passage has a relatively large passage cross-sectional area and opens toward the combustion chamber in the axial direction of the cylinder, and the auxiliary intake passage has a relatively large passage cross-sectional area. An intake system has been proposed in which the downstream end of the main intake passage is opened directly upstream of the intake valve in the tangential direction of the cylinder.
Publication No. 187519).

By the way, in order for the auxiliary intake passage to generate a strong and sufficient swirl without disturbing the intake air, the downstream end of the auxiliary intake passage should be smoothly bent or curved in the tangential direction of the outer circumference of the cylinder. Must be configured.

However, in the conventional device, the connection relationship between the wall of the downstream end of the auxiliary intake passage and the wall of the main intake passage is not taken into account, so the downstream end of the auxiliary intake passage cannot be bent or curved in the direction of the outer circumference of the cylinder. As the length increases, the intake flow flowing out from the downstream end opening collides with the cylinder outer peripheral side wall of the main intake passage at an obtuse angle, and due to this collision, the intake flow is bent toward the inner peripheral direction, creating a swirl. The problem was that it was said to be a hindrance. This tendency is particularly noticeable in the intake air flowing down the auxiliary intake passage close to the cylinder outer peripheral wall.

(Object of the Invention) The present invention solves the above-mentioned problems by continuously connecting the wall on the outer peripheral side of the cylinder at the downstream end of the auxiliary intake passage to the main intake passage at a predetermined curvature. An object of the present invention is to provide an engine intake device that can smoothly supply intake air flowing out of an intake passage into a combustion chamber and is effective in generating swirl.

(Structure of the Invention) In the present invention, the intake passage is composed of a main intake passage and an auxiliary intake passage, and the downstream end of the auxiliary intake passage opens immediately upstream of the intake valve of the main intake passage. In an engine intake system in which intake air supply from a passage to a combustion chamber is restricted, the auxiliary intake passage is oriented in a cylinder tangential direction, and a partition wall is present between the main intake passage and the auxiliary intake passage. The auxiliary intake passage opens into the main intake passage downstream of the end of the partition wall of the lever, and the wall of the auxiliary intake passage on the cylinder outer circumferential side has an upstream portion downstream of a predetermined position corresponding to the end of the partition wall. The downstream part of the predetermined position smoothly connects to the upstream part and curves in the opposite direction to the upstream part, and the main intake air The angle of the port with respect to the wall becomes gradually smaller, and the downstream end thereof is formed to smoothly continue around the opening to the combustion chamber at the downstream end of the main intake passage.

With this configuration, even if the auxiliary intake passage is largely deflected toward the cylinder outer circumference, the intake air flowing out from the auxiliary intake passage is smoothly and streamlined into the combustion chamber as a swirling flow, and the flow is disturbed and dispersed. Then, it was something I had never seen before.

(Embodiment) FIGS. 1 and 2 show an embodiment of the present invention, in which a combustion chamber 3 is formed by a cylinder 1 and a cylinder head 2, and an intake port 4 and an exhaust port 5 are opened in this combustion chamber 3. The intake port 4 and the exhaust port 5 are provided with an intake valve 6 and an exhaust valve 7, which are opened and closed in a certain interlocking relationship with the rotation of the engine. Further, an intake passage 8 and an exhaust passage 9 are connected to the intake port 4 and the exhaust port 5, respectively, and the intake passage 8 is composed of an intake manifold 10 connected to the cylinder head 2, a carburetor 12 having a throttle valve 11, etc. has been done. In addition, the intake passage 8 consists of a main intake passage 8a for high-load operation and an auxiliary intake passage 8b for low-load operation, and a control valve 13 is interposed in the main intake passage 8a to open and close depending on the operating state of the engine. ing.

The auxiliary intake passage 8b has an upstream end opened to the main intake passage 8a downstream of the throttle valve 11 and upstream of the control valve 13, and further passes downstream through the lower side of the main intake passage 8a via the partition wall 8c. An auxiliary intake port 8d is located immediately upstream of the intake valve 6 whose end is the main intake passage 8a.
It has been opened as.

The main intake passage 8a has a relatively large passage cross-sectional area, and is smoothly bent or curved within the cylinder head 2 so that its downstream end opens parallel to the axis of the cylinder 1. On the other hand, the auxiliary intake passage 8b has a relatively small passage cross-sectional area, and is smoothly bent or curved so that its downstream end opens in a direction perpendicular to the axis of the cylinder 1 and oriented in the tangential direction of the cylinder 1.

In the present invention, the walls 8e and 8f of the auxiliary intake passage 8b on the outer peripheral side of the cylinder 1 are curved as follows. In other words, as shown in Figure 2,
The auxiliary intake passage 8b opens into the main intake passage 8a on the downstream side of the terminal end of the partition wall 8c, but the wall 8e on the cylinder outer peripheral side of the auxiliary intake passage 8b goes downstream to a predetermined position A corresponding to the terminal end of the partition wall. The angle of the wall 8f with respect to the wall of the main intake port 8a gradually decreases downstream of the predetermined position A, so that the wall 8e on the upstream side and the wall 8e on the downstream side are wall 8f
It curves in opposite directions and has a smoothly connected shape. The downstream end of the wall 8f is
It is formed so as to be smoothly continuous around the intake port (opening to the combustion chamber) 4 at the downstream end of the main intake passage.

Further, the control valve 13 has a diaphragm device 14.
It is designed to be driven to open and close depending on the operating state of the engine. That is, the diaphragm device 14 detects the negative pressure in the intake passage 8 downstream of the throttle valve 11 through the negative pressure introduction path 15, and when the engine load is large and the opening degree of the throttle valve 11 is large and the negative pressure becomes small, the link mechanism is activated. The control valve 13 is opened via the link mechanism 16, and conversely, when the engine load is small, the opening degree of the throttle valve 11 is small, and the negative pressure becomes large, the control valve 13 is opened via the link mechanism 16.
3. Note that, instead of detecting the negative pressure as described above, the operating state of the engine may be detected by other detection means and the diaphragm device 14 may be controlled by the control unit 17.

Next, the operation of the above configuration will be explained.

First, during low-load operation, the control valve 13 is closed as described above, and air is taken in through the auxiliary intake passage 8b. Therefore, the auxiliary intake port 8d
Since the downstream end of the auxiliary intake passage 8b is oriented in the tangential direction of the cylinder 1, the intake air flowing out is oriented in the tangential direction of the cylinder 1, as shown by the arrow S in FIG. The fuel is supplied to the main intake passage 8a, and is further supplied into the combustion chamber 3 through the upper surface of the umbrella portion of the intake valve 6 while generating a large swirl. At this time, up to a predetermined position A corresponding to the terminal end of the partition wall 8c, the wall 8e on the cylinder outer peripheral side of the auxiliary intake passage 8b becomes closer to the cylinder tangential direction as it goes downstream, so that the intake air flows in the cylinder tangential direction. Directed. On the downstream side of the predetermined position A, the wall 8f curves so that the angle with the wall of the main intake passage 8a gradually becomes smaller while continuing smoothly with the wall 8e and reaches around the intake port 4, so that the auxiliary intake Port 8d is main intake passage 8a
From the position where the opening begins, the flow near the wall 8f is smoothly guided in the direction along the wall 8f. This prevents the intake air flowing down the auxiliary intake passage 8b from colliding with the main intake passage 8a and the wall 8f of the auxiliary intake port 8d at a large angle, so that it does not collide with the wall of the main intake passage as in the conventional case. If the intake air is bent toward the inner circumference of the cylinder, the leakage will disappear. Therefore, the generation of swirl in the intake air supplied to the combustion chamber 3 is not inhibited or the swirl is dispersed, and the intake resistance does not increase. That is, during low-load operation, a strong swirl can be generated in the intake air supplied to the combustion chamber 3, and combustibility can be improved.

Next, during high-load operation, the control valve 13 is open as described above, and the intake air is mainly supplied to the main intake passage 8.
Therefore, the filling efficiency is increased due to the small intake resistance, and the generation of swirl is suppressed. In this way, the demands of the engine during high-load operation can be satisfied, and the output can be improved.

Although the above embodiments of the present invention show one cylinder having one intake port, it is also possible to have two intake ports and the main intake passage branches at the downstream end. This method can be used in various ways, such as even if the downstream end of the auxiliary intake passage opens into the main intake passage immediately upstream of the intake valve of one intake port. can be applied.

(Effects of the Invention) As described above, according to the present invention, the auxiliary intake passage is oriented in the tangential direction of the cylinder, and the wall of the auxiliary intake passage on the cylinder outer peripheral side is located upstream from a predetermined position corresponding to the end of the partition wall. The main intake port is curved in the opposite direction while being smoothly connected to the downstream side, so that the angle to the wall of the main intake port gradually becomes smaller on the downstream side, so that the main intake port does not flow out from the auxiliary intake passage, especially during low load operation. The intake air does not collide with the side wall of the main intake passage at an obtuse angle, and therefore the intake air can be smoothly supplied into the combustion chamber, dispersing the swirl and reducing intake resistance, making it possible to generate a strong swirl. It is possible to improve combustibility.

[Brief explanation of drawings]

FIG. 1 is a side view of an intake system for an engine according to an embodiment of the present invention, and FIG. 2 is an explanatory plan view of essential parts of the intake system for the same engine. 1... Cylinder, 6... Intake valve, 8... Intake passage, 8a... Main intake passage, 8b... Auxiliary intake passage, 8e... Wall of the auxiliary intake passage on the cylinder outer peripheral side.

Claims (1)

[Claims] 1 The intake passage is composed of a main intake passage and an auxiliary intake passage, and the downstream end of the auxiliary intake passage opens immediately upstream of the intake valve of the main intake passage, and the intake air is supplied from the main intake passage to the combustion chamber during high loads. In the engine intake system in which the auxiliary intake passage is oriented in the tangential direction of the cylinder, a partition wall is present between the main intake passage and the auxiliary intake passage, and the downstream end of the partition wall is The auxiliary intake passage opens into the main intake passage, and the wall of the auxiliary intake passage on the cylinder outer circumferential side approaches the tangential direction of the cylinder as it goes downstream from a predetermined position corresponding to the terminal end of the partition wall. The downstream portion of the predetermined position is smoothly connected to the upstream portion and curved in the opposite direction to the upstream portion, so that the angle with respect to the wall of the main intake port gradually becomes smaller. What is claimed is: 1. An intake system for an engine, wherein the downstream end of the main intake passage is formed so as to be smoothly continuous with the periphery of the opening to the combustion chamber at the downstream end of the main intake passage.