JPH0216329A - Intake device of engine - Google Patents

Abstract

PURPOSE:To prevent carbide from depositing in the vicinity of a throttle valve, in a system where a part of intake air is ejected from an ejection port which is formed on an intake passage pointing to a combustion chamber, by opening one side of an auxiliary intake passage whose other side is communicated to the ejection port, in a specific position around the throttle valve. CONSTITUTION:An ejection port 14 of a small cross section is opened in the vicinity of an intake valve 6 located in an intake port 7a, and the direction of the ejection port 14 is set nearly in parallel with the top surface of a piston 4 inside a combustion chamber 1 and in the direction pointing in the circumference direction of a cylinder hole. An auxiliary intake passage 16 is communicated to the ejection port 14, and the other end of the auxiliary intake passage 16 is communicated to several small holes 18 opened on the wall surface of an intake passage 7 opposing to the circumference surface 17a of a butterfly throttle valve 17 when the butterfly throttle valve 17 of a carbureter 12 is in the state of an idling opening. In addition, each small hole 18 is formed at the position, a little (only S dimension) down course side from the end edge 17b of the upper course side of the throttle valve 17. Thereby it is possible to prevent carbide from depositing in the vicinity of a throttle valve 17 during idling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides an injection port oriented toward the combustion chamber in the intake passage of a four-stroke engine, from which a part of the intake air is ejected into the combustion chamber at high speed, and as a result, the intake air generated inside the combustion chamber. This invention relates to a device for improving combustion by high-speed vortex flow.

An object of the present invention is to minimize the reduction in idling opening that occurs due to the installation of a sub-intake passage connected to the jet nozzle. That is, there is a structure in which the sub-intake passage bypasses the throttle valve in order to utilize the pressure difference before and after the throttle valve as a means for generating a sub-intake flow in the sub-intake passage.

This structure is advantageous in that it does not require major modifications to the intake passage and the entire structure can be made compact. However, since the overall intake air volume increases by the amount equivalent to the flow rate of the sub-intake, it is difficult to reduce the idling opening of the throttle valve. It becomes necessary to reduce the idling speed and prevent excessive idling speed.

However, if the opening degree of the throttle valve is reduced during idling operation, the amount of carbide deposited near the throttle valve increases due to the burned gas blowing back from the combustion chamber, which may impair combustion stability during low-load operation.

This invention was made to eliminate such a problem, and the upstream end of the auxiliary intake passage is arranged to face the circumferential surface of the throttle valve when the intake passage is idling, and to be located downstream of the upstream edge of the throttle valve. It is located on the side and opened. The following will explain the embodiments shown in the drawings.

In the figure, 1 is a combustion chamber, which is formed by a cylinder 2, a cylinder head 3, and a piston 4. 5 is a spark plug. An intake passage 7 opened and closed by an intake valve 6 and an exhaust passage 9 opened and closed by an exhaust valve 8 communicate with the combustion chamber 1 . The intake passage 7 includes an intake boat 7a1 formed in the cylinder head, a spacer 11 made of a heat insulating material connected to the intake boat 7a1, a negative pressure responsive variable venturi carburetor 12, an air cleaner 13, and the like.

There is a jet port 1 with a small cross-sectional area near the intake valve 6 of the intake port 7a.
4 is open. Here, the opening of the spout 14 is said to have a small cross-sectional area because the diameter of the suction boat 7a is approximately 30 mm, while the diameter of the spout is set to 3 mm. The jet nozzle 14 is opened at the tip of the nozzle member 14a, and the nozzle member 14a is inserted and fixed from the joining fabric of the cylinder 2 and the spacer 11 into a small hole 15 provided along the port 7a, and the tip thereof is connected to the intake boat. It faces 7a. 16
is an auxiliary intake passage communicating with the jet nozzle 14. Spout 14
As shown in FIG. 3, the direction is substantially parallel to the top surface of the piston 4 in the combustion chamber 1, and is oriented in the circumferential direction of the cylinder 2 hole.

The other end of the sub-intake passage 16 is connected to a butterfly-shaped throttle valve 17 of the carburetor 12.
When the opening is at idling, three small holes 18.18 open in the wall surface of the intake passage 1 facing the circumference 117a.
is connected to. What I would like to particularly emphasize here is that the small hole 18 is positioned downstream of the upstream edge 17b of the throttle valve 17 by a distance of 8 minutes, although it fits slightly. be. Reference numeral 19 denotes a piston-shaped automatic valve of the carburetor 12, which is a conventionally known valve that responds to the venturi negative pressure generated on its lower surface and increases its opening when the negative pressure is high (low pressure). 21 is an auxiliary opening located downstream of the small hole 18.

Next, the operation of this embodiment will be explained. When the intake valve 6 opens at the end of the exhaust stroke and the intake stroke begins, the intake air metered by the throttle valve 17 is sucked into the combustion chamber 1, aged in the subsequent compression stroke, and then ignited by the ignition plug 5. and burn it.

Now, when the throttle valve 17 is at the idling opening degree, the intake air passes through the narrow space around the outer circumference of the throttle valve 17 at subsonic speed, so its pressure is low and the flow rate flowing into the sub-intake passage 16 is small. In particular, the intake port of the sub-intake passage 16 and the small hole 18 facing the circumferential surface 17a of the throttle valve 17,
Since it opens downstream from the upstream edge 17b, the sub-intake flow rate during idling can be minimized. Next, when the throttle valve 17 is opened to increase the engine output, the small hole 18 becomes on the upstream side of the throttle valve 17. While the amount of intake air passing through increases, a pressure difference across the throttle valve 17 acts between the small hole 18 and the jet port 14, so a high-speed sub-intake flow is generated. This sub-intake air flow is
The air is ejected at high speed from the intake bow) and flows into the combustion chamber 1 through the airflow flowing at a distance of 7 m, creating countless minute turbulences at the interface between the two airflows. Further, since the jet port 14 is oriented in the circumferential direction of the cylinder 2 hole in the combustion chamber 1, the sub-intake air flow generates a high-speed intake vortex around the axis of the cylinder 2. This high-speed vortex flow remains until the end of the compression stroke without being greatly attenuated by the rise of the piston 4. For this reason, combustion occurs rapidly and stably during the ignition and explosion stroke that continues. As the opening degree of the throttle valve 17 further increases, the pressure difference across the throttle valve 17 decreases, resulting in a tendency for the sub-intake flow to decrease. At this time, the auxiliary opening 21 is also
7 on the atmospheric side, the sub-intake flow rate increases. Therefore, the auxiliary opening 21 prevents the auxiliary intake flow from increasing excessively in the low opening range of the throttle valve 1γ to prevent misfires, and maintains the effect of the auxiliary intake flow up to the medium opening range. .

As explained above, the present invention has a jet opening opened in the intake passage near the intake valve, which is connected via the auxiliary intake passage to the peripheral surface of the throttle valve at the idling opening position and from the upstream edge. It is located on the downstream side and opens into the wall of the intake passage. Therefore, the sub-intake air flow that reaches the jet port via the sub-intake passage is almost stopped when the throttle valve is in the idling position, so there is no need to reduce the idling opening of the throttle valve. That is, the opening degree of the throttle valve during idling operation can be set to approximately the same opening degree as an engine without a sub-intake passage, and an increase in the amount of carbide deposited on the wall surface of the intake passage near the throttle valve can be prevented. This has the effect of avoiding the tendency of the air-fuel ratio to become unstable.

Note that the number of small holes 18 is not limited to a plurality of holes, and the shape may be circular, or triangular or rectangular as necessary.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a sectional view of a four-stroke engine, and FIG. 2 is a partial plan view thereof. 3 is a sectional view taken along line [-III] in FIG. 1, FIG. 4 is an enlarged view of the main part, and FIG. 5 is a sectional view taken along line V--■ in FIG. 14φ... Jet outlet, 16 fist... Sub-intake passage, 17.
...Mound-shaped throttle valve, 17a...Surrounding surface, 17b...
...Upstream edge, 18...Small hole, 21...Auxiliary opening.

Claims (1)

[Claims] A butterfly-shaped throttle valve (17) is provided in the intake passage (7) that connects to the combustion chamber (1) via the intake valve (6), and the intake passage (7)
A jet nozzle (14) with a small cross-sectional area oriented toward the combustion chamber is opened near the intake valve (6), and an auxiliary intake passage (16) communicating with this jet nozzle (14) is provided. )
The other end is connected to the throttle valve (1) on the wall of the intake passage (7).
The opening is located near 7), facing the periphery (17a) of the throttle valve when the throttle valve (17) is at the idling opening, and located downstream from the upstream edge (17b) of the throttle valve. An engine intake system characterized by: