JPH0318622A - Intake device of engine - Google Patents

Abstract

PURPOSE:To improve the intake efficiency from low to high speed by opening and closing opening and closing valves inside long and short pipes, to which respective carburetors are connected, in response to engine speed. CONSTITUTION:An intake pipe 3 which is branched into two pipes, a long pipe 4 and a short pipe 5 are connected to an intake hole 2 of an engine 1. Respective carburetors 8 are connected to the long pipe 4 and the short pipe 5, and opening and closing valves 6, 7 are provided in the long pipe 4 and the short pipe 5. A control circuit 12 is actuated by an ignition pulse of an ignition unit 11 so as to operate the opening and closing valves 6, 7 with a servo motor 13. Only the opening and closing valve 6 of the long pipe 4 is opened at the low speed range, while only the opening and closing valve 7 of the short pipe 5 is opened at the middle speed range. Both the opening and closing valves 6, 7 are opened at the high speed range. Consequently, intake surging wave is used effectively for charging intake air at both the low and middle speed range so as to improve the intake efficiency. Intake quantity is increased at the high speed range so that it is possible to improve the output.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine that can improve intake efficiency and increase output.

[Conventional technology]

Generally, an engine has one intake passage, which is connected to a carburetor, so that the intake air mixed with fuel from the carburetor is sucked into the engine.

In addition, some engines have two intake passages, one with a large area and one with a small area, which are used depending on the rotational speed. For example, JP-A-60-1 569294, JP-A-60
See Publication No.-156926.

[Problem to be solved by the invention]

Intake of the engine occurs rapidly and intermittently.

Therefore, pulsating waves of intake air are generated in the intake passage.

Moreover, as the engine speed changes, the intake timing interval also changes, and the wavelength of the pulsating wave changes. Normally, the length of the intake passage is constant, so there is a rotation range in which the pulsating wave effectively acts on filling the intake air.
On the other hand, there is a rotational range that makes it difficult to fill the intake air. Generally, the length of the intake passage is set in consideration of the operating conditions of the engine so that the intake efficiency is improved in the most used rotation range.

In view of this, this invention branches the intake pipe into a long pipe and a short pipe, connects a carburetor to each pipe, and uses an on-off valve depending on the rotation range to improve intake efficiency from low speeds to high speeds and increase output. The purpose of this invention is to obtain an engine intake system that can achieve this.

(Means for Solving the Problems) In order to achieve the above object, an engine intake system of the present invention connects an intake pipe which is bifurcated into a long pipe and a short pipe to an intake hole of the engine, and A vaporizer is connected to each of the short and long pipes, and on-off valves are installed in the long and short pipes. In the low speed range, only the on-off valve of the long pipe is opened, in the medium speed range, only the on-off valve of the short pipe is opened, and in the high speed range, only the on-off valve of the long pipe is opened. The problem lies in the fact that the on-off valves for both the long pipe and the short pipe are opened.

[Effect]

The exhaust pipe is bifurcated into a long pipe and a short pipe, and the long pipe is set to a length that allows the intake pulsation waves in the low-speed range where the intake air is gentle and the intake intervals are long to be effectively utilized. Further, the short pipe is set to a length that allows effective use of the intake pulsation wave in which the intake air in the medium speed range becomes faster and the intake interval becomes shorter. In a low speed range, intake air is supplied only from the long pipe by listening to the on-off valve of the long pipe, and in a medium speed range, intake air is supplied only from the short pipe by opening the on-off valve of the short pipe.

Therefore, the intake pulsating waves can be effectively used to fill the intake air in both the low speed range and the medium speed range, thereby increasing the intake efficiency and improving the output. At high speeds, there is a sudden intake of air, the interval between intakes is short, and a large amount of intake air is required. Therefore, by listening to the on-off valves of both the long and short pipes, you can increase the amount of intake air and improve the output. can.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

An intake pipe 3 is connected to an intake hole 2 of an engine 1.

The intake ¥13 is divided into two on the inlet side, and has a long pipe 4.
A short pipe 5 is provided. A butterfly-shaped on-off valve 6 is provided in the long pipe 4, and an on-off valve 7 is similarly provided in the 5rl pipe 5. And long pipe 4 and short i'! A vaporizer 8 is connected to each end of 5,
Two vaporizers 8 are each connected to an outlet 10 of an air cleaner 9. The long pipe 4 is set so that the length of the entire intake passage is such that the intake pulsating waves in the low speed region effectively fill the intake air. Further, the short pipe 5 is set to such a length that the entire length of the intake passage is effectively filled with intake air by intake pulsating waves in the medium speed range. The two opening/closing valves 6.7 operate the control circuit 12 with the ignition pulse of the ignition unit 11, and are opened/closed by the servo motor 13. il at the rotation speed of engine 1
In the low rotation range (range shown in Figure 3 A), only the open/close valve 6 of the long pipe 4 is opened and the short pipe 5 is closed; in the middle rotation range (range shown in Figure 3 B), Only the open/close valve 7 of the short pipe 5 is closed, and the long pipe 4 is closed.In the high rotation range (range C in Fig. 3), the two open/close valves 6 and 7 are both closed. Air is supplied from both the long pipe 4 and the short pipe 5 to brighten the intake air.

As a result, in the low speed range and medium speed range, the intake air filling efficiency can be increased by the intake pulsation effect, and in the high speed range, the intake suspension can be increased, increasing the output shown by the dotted line in Figure 3 to the output curve shown by the solid line. Therefore, the output can be increased.

(Effects of the Invention) As explained above, since the present invention is configured as described above, a long pipe is used in the low speed range of the engine, and a short pipe is used in the middle speed range, so that the inside of the intake passage is controlled. The pulsation of the intake air that occurs during the engine speed increases the filling efficiency of the intake air, and in the high rotation range, the intake air can be increased using both the good pipe and the short pipe, increasing the engine output and increasing the engine output throughout the rotation range. It can be output. Furthermore, since two carburetors are used, each carburetor can be set according to the rotation range used, and intake air with an appropriate air-fuel ratio can be supplied.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, with Figure 1 being a side view and Figure 2 being a partial view! Figure 3 is a cross-sectional plan view, and Figure 3 is an output curve diagram. 1... Engine, 2... Intake hole, 3... Intake pipe,
4...Long pipe, 5...Short pipe, 6...Opening/closing valve, 7...
・Opening/closing valve, 8... vaporizer.

Claims (1)

[Claims] Connect an intake pipe that is bifurcated into a long pipe and a short pipe to the intake hole of the engine, and connect a carburetor to each of the long pipe and short pipe,
On-off valves are installed in the long and short pipes, and in the low speed range, only the long pipe on-off valve is opened, in the medium speed range, only the short pipe on-off valve is opened, and in the high-speed range, both the long and short pipe on-off valves are opened. An engine intake device characterized by being opened.