JPH0367019A - Suction device of engine - Google Patents

Abstract

PURPOSE:To carry out a smooth operation and reduce the exhoust of uncombusted hydrocarbons by furnishing an aux. throttle valve shutting only at the time of low load in a position of a suction passage downstream a throttle valve, putting a vent situated eccentric from the combustion chamber in communication with point between the valves and in the neighborhood of a suction hole, and accomplishing good performance of combustion under a low load operation. CONSTITUTION:Because the degree of opening of the primary throttle valve 1c is less immediately after starting of an engine or under low load operation, the neg, pressure in a suction passage 15 is high, and accordingly a pressure chamber 17a is sucked and an operation rod 17d is pulled up. Therefore, an aux, throttle valve 16 is turned and the suction passage 15 is blocked or put in low degree opening. When this aux. throttle valve 16 is shut, the mixture gas supplied from a carburettor 1 passes through communication paths 24, 25 and a draft pipe 22 and is inhaled into the combustion chamber 9 from a draft hole 21. This communication path or draft hole 21 is thinner relatively than the suction passage 15, and the draft hole 21 is oriented toward the combustion chamber 9 and opens in a potion eccentric from the center of the combustion chamber, so that the mixture gas supplied therefrom becomes a high speed jet stream and is inhaled into the combustion chamber 9 so as to generate there swirls.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for an engine that facilitates smooth operation and takes measures against exhaust gas, especially during low-load operation.

Generally, when the engine is operated at low load, especially at low speed and low load, the filling efficiency of the air-fuel mixture taken into the combustion chamber is low, so the flame propagation speed is low and unstable. As a result, the thermal efficiency of the engine is low, surging occurs and the engine runs unsmoothly, and there are other problems such as incomplete combustion components such as carbon oxides and unburned hydrocarbons being emitted. Therefore, in recent years,
Techniques have begun to be used to increase the flame propagation speed by creating appropriate turbulence in the air-fuel mixture within the combustion chamber. This method involves creating a vortex by a jet flow from the squish area formed by the piston toward the center of the combustion chamber in the latter half of the compression stroke, and using an intake valve with a shroud to draw air into the combustion chamber. There is a method of giving the air-fuel mixture a tangential movement called swirl. However, in the former method, unburned hydrocarbons are released into the squish region, and in the latter method, the presence of the shroud impedes suction efficiency during high-speed operation, which is not necessarily practical. It cannot be said that the results were sufficient in terms of this aspect.

The present invention has been made to solve these problems, and includes a throttle valve and an auxiliary throttle valve that is located downstream of the throttle valve and closes only at low load, in the intake passage connected to the intake port of the combustion chamber. This extremely simple configuration allows communication between the throttle valve and a vent that opens toward the combustion chamber and is offset from the center of the combustion chamber, creating a school inside the combustion chamber, thereby reducing low speed and low load. To provide an intake system for an engine that can be operated smoothly even when the engine is in use, and can reduce the emission of unburned harmful substances. below,
The configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view of an intake device according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a bottom view of a cylinder head. In these figures, the reference numeral 1 indicates a composite carburetor, which includes a carburetor main body 1a, a choke valve 1b, a primary throttle valve 1c that is opened and closed artificially, and a secondary throttle valve that is opened at high output. It consists of a throttle valve 1d, etc. 2 is a cylinder, 3 is a piston, 4 is a cylinder head equipped with a combustion chamber 9 having an intake passage 5, an exhaust passage 6, and intake/exhaust ports 7, 8 at the front and rear thereof, 10 is an intake valve, 11 is an exhaust valve, 12 13 is an ignition plug, 13 is an exhaust pipe, and 14 is a manifold intake pipe that connects the carburetor 1 and the intake passage 5, forming an intake passage 15, and a branch part of the intake passage 15 is heated by a cooling water riser 15a. reactor.

These are generally wide (there is no particular difference in structure from the known internal combustion engine).

Reference numeral 16 denotes an auxiliary throttle valve provided in the intake passage 15 so as to be openable and closable. In this embodiment, this throttle valve 16
! Opening/closing is controlled in accordance with pressure fluctuations within the i-way 15. 17 is a control opener in charge of this opening/closing control, and this opener 17 connects the intake passage 15 with the ventilation passage 18.
It is composed of a pressure chamber 17a, a diaphragm 17b, a compression spring 17c, an actuating rod 17d, etc., which are communicated with each other.

Reference numeral 19 indicates a lever fixed to the shaft of the auxiliary throttle valve 16, and reference numeral 2° indicates a vent opening connected to the lever 19 and the operating rod 17d. As shown, the opening is directed toward one side from the center of the combustion chamber 9.

The ventilation port 21 is connected to a ventilation pipe 22, a communication pipe 23.
24 communicates with the upstream side of the auxiliary throttle valve 16 of the intake passage 15.

Therefore, as shown in Fig. 1, when the engine is stopped and when the first
During high load and high rotation when the throttle valve 1c is open,
Since the intake passage 15 has a high pressure or a low intake negative pressure close to it, the elastic force of the compression spring 17c prevails and the actuating rod 1
7d is not pulled up, so the auxiliary throttle valve 16 is in the open state. On the other hand, immediately after starting the engine or during low-load operation, the opening degree of the primary throttle valve 1c is small, so the negative pressure in the intake passage 15 is high, and accordingly, the pressure chamber 1
7a is attracted and the actuating rod 17d is pulled up, so that the auxiliary throttle valve 16 rotates and closes the intake passage 15 or opens it to a low degree. When the auxiliary throttle valve 16 closes, the air-fuel mixture supplied from the carburetor flows through the communication passage 24, 23 and the vent pipe 2.
2 and is drawn into the combustion chamber 9 from the vent 21.

These communication passages or vents 21 are connected to the intake passage 15.
Compared to the above, the vent 21 is relatively narrow, and since the vent 21 is oriented towards the combustion chamber 9 and opens at a position offset from the center of the combustion chamber, the air-fuel mixture supplied from here is a high-speed jet. Then, it is sucked into the combustion chamber 9 and causes school.

Figure 4 shows another embodiment of the present invention, and while the previous embodiment controls the opening and closing of the auxiliary throttle valve 16 using pressure fluctuations in the intake passage 15, this embodiment In this example, this is done mechanically by a lever 31 that is rotated by operating an accelerator (not shown), and an auxiliary throttle valve 16 is installed in the primary intake passage 15' in the main body 1a of the compound carburetor 1. Here is an example. In other words, for the lever 31 connected to the accelerator by the wire 32,
The primary throttle valve 1c is directly connected to the auxiliary throttle valve 1.
6 is bored in the lever 31 and connected via a long hole 33. Therefore, when the lever 31 rotates in the direction of the arrow due to accelerator operation, the primary throttle valve 1c immediately rotates in the opening direction, whereas the auxiliary throttle valve 16 rotates by the amount of play in the longitudinal direction of the elongated hole 33. For example, the primary throttle valve 1c does not rotate when the opening degree is low, but opens when the opening degree is further increased. Note that other parts are not substantially different from the embodiment shown in FIG.
Identical or equivalent members are given the same reference numerals, and their explanations will be omitted.

In the above embodiments, the intake passage 15, the primary side intake passage 15' of the composite carburetor, and the vent 21 are connected by a communication pipe exposed outside the machine, but the V wall of the intake pipe Of course, this intake passage may be provided inside the cylinder head, or a structure may be adopted in which a pipe body is provided inside the intake passages 5 and 15 shown in the figure. In this case, it goes without saying that a part of the auxiliary throttle valve 16 must be provided with a cutout groove into which this tube fits.

In addition, in the examples shown in the figures, examples using a composite humidifier are shown, but it can be implemented not only in a single-barrel type vaporizer but also in a single-barrel humidifier equipped with a piston-type throttle valve. .

As explained above, according to the present invention, an auxiliary throttle valve that closes only at low load is provided downstream of a throttle valve that is provided in the intake passage and is manually operated, and a combustion valve is provided between these throttle valves and near the intake port. Because it communicates with a single vent that is oriented toward the chamber and opened toward one side from the center of the twisting chamber, swirl occurs in the combustion chamber, resulting in faster flame propagation and better combustion under low loads. Therefore, smooth operation without surging can be expected, and the release of unburned hydrocarbons can be reduced.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing one embodiment of an engine intake system according to the present invention, Fig. 2 is a 100-degree view thereof, Fig. 3 is a bottom view of a cylinder head, and Fig. 4 is another embodiment. FIG. 3 is a longitudinal cross-sectional view of the intake device. 1... Carburetor, 1C... Primary throttle valve, 7...
...Intake port, 15...Intake passage, 16...Auxiliary throttle valve, 21...Vent.

Claims (1)

[Scope of Claims] A throttle valve and an auxiliary throttle valve located downstream of the throttle valve and closing the intake passage only during low load are provided in the intake passage connected to the intake port, and the intake passage between these throttle valves and near the intake port is An intake device for an engine, characterized in that a passage communicates with one vent opening oriented toward a combustion chamber and located at a position biased to one side from the center of the combustion chamber.