JPS60156929A - Suction device for engine - Google Patents

Abstract

PURPOSE:To enlarge a synchronized range of a suction inertia effect in a simple structure, by dividing a suction passage reaching to one cylinder into two parts, while installing an on-off valve in each passage, and opening or closing the valve according to an engine speed. CONSTITUTION:A suction passage 3 is partitively formed into two parts, namely, a first suction passage 3a being small in a passage area and a secondary suction passage 3b being large in the passage area, while a first on-off valve 8 and a second on-off valve 9 are interposingly installed in each passage. A control unit 13 inputs a signal out of an engine speed sensor 15, driving and controlling both first and second actuators 11 and 12 corresponding to an engine speed variation, and the first on-off valve 8 alone is opened at a low speed range, then the second on-off valve 9 is opened at a medium speed range, and both valves 8 and 9 are opened at a high speed range whereby air column frequency in the suction passage 3 and a period of time in a suction period are synchronized, rendering a suction inertia effect maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system, and in particular, to improving output by utilizing inertia supercharging by synchronizing the air column vibration of the intake system with the intake period. The present invention relates to an improvement of an engine intake system.

(Prior Art) Generally, the flow in the intake pipe is a so-called pulsating flow, and when the intake valve opens and the intake stroke begins, the air column in the intake pipe is accelerated due to the negative pressure generated in the cylinder and flows into the cylinder.

During this time, the cylinder internal pressure and volume change with the downward movement of the piston, and at the same time the intake pipe internal pressure and speed also gradually change both in time and location. The pressure waves generated in the cylinder propagate through the intake pipe, are reflected at the surge tank, and return to the cylinder, and this phenomenon is repeated in the intake system. By synchronizing the frequency of the pressure change caused by the downward movement of the piston with the natural frequency of the intake system determined by the volume of the intake pipe and cylinder, an intake inertia effect can be obtained, improving volumetric efficiency and increasing output. It is well known that C can be realized.

The natural frequency of the intake system is determined by the length and cross-sectional area of the intake passage, and the average cylinder volume during the intake period.The range of engine speeds that are synchronized with this natural frequency is widened, and the intake inertia effect is utilized. In order to expand the improvement range, various techniques have been proposed in which the length or area of the intake passage is variable (for example, Japanese Patent Application Laid-Open Nos. 48-58214 and 115819). No., Japanese Patent Publication No. 58-1199
No. 19).

However, in these prior art techniques, the effect of expanding the upward range in the exit direction by utilizing the intake inertia effect is small and insufficient;
In addition, there are problems such as the need for a complicated mechanism to widen the range of change, and it is desired to obtain large tuning over a wider range with a simple structure.

(Object of the Invention) In view of the above circumstances, the present invention aims to improve output by changing the passage area of the intake passage in multiple stages using a simple structure so that the inertia effect can be maximized at each rotation speed over a wide range. The object of the present invention is to provide an intake system for an engine that has the following characteristics.

(Structure of the Invention) The intake device of the present invention divides the intake passage leading to one cylinder into a first intake passage with a small passage area and a second intake passage with a large passage area, and opens and closes each intake passage. By providing a switching means equipped with a valve and opening and closing the above-mentioned on-off valve according to the engine speed, the area of the intake passage can be divided into three areas: only the first intake passage, only the second intake passage, and the first and second intake passages. This feature is characterized by switching in stages.

(Effects of the Invention) According to the present invention, by changing the intake passage area in three stages by switching between the two intake passages, the tuning range of the intake inertia effect can be expanded with a simple structure, and a large intake air intake can be achieved over a wide rotation range. In addition to effectively increasing the output direction due to the inertia effect, it is also possible to improve performance by increasing the intake flow velocity in the low rotation range.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional front view of essential parts of a multi-direction engine equipped with an intake device, and FIG. 2 is a sectional view taken along the line 1--2 in FIG.

An intake passage 3 that communicates with the combustion chamber 2 of each cylinder of the engine 1 is provided with a surge tank 5 downstream of the throttle valve 4, and is branched downstream of the surge tank 5 and connected to each cylinder independently.

On the downstream side of the throttle valve 4, the intake passage 3 in the vicinity of the combustion chamber 2 formed in the cylinder head 6 from the surge tank 5 is separated by a partition wall 7 into a first intake passage 3a having a relatively small passage area; The first intake passage 3a is divided into the first intake boat 12a of the combustion chamber 2, and the second intake passage 3b is divided into the second intake passage 3b, which has a relatively large passage area.
Each of them opens into the intake boat 12b.

A first on-off valve 8 is interposed in the first intake passage 3a, and a 21711 on-off valve 9 is interposed in the second intake passage 3b, and the intake passage area is switched by opening and closing both on-off valves 8.9. Means 1o is provided, and both on-off valves 8.9 are connected to their rotation shafts 8.
a, 9. a are each associated with an actuator 11.12, which actuator 11.12 is connected to a control means 13 (
The first and second intake passages 3a and 3b are independently separated by operation based on a control signal from a control unit (113L), and when intake air is supplied only by the first intake passage 3a, and when only the second intake passage 3b is supplied. The area of the intake passage is changed depending on when the intake air is supplied by the intake passages 3a and 3b and when the intake air is supplied by the intake passages 3a and 3b.

A portion of the partition wall 7 downstream of the on-off valves 8 and 9 is removed so that the first and second intake passages 3a and 3b on both sides communicate with each other, and a fuel injection nozzle 14 is disposed facing this communication portion. Both intake passages 3a by a single fuel injection nozzle 14,
3b can be supplied with fuel.

An engine rotational speed signal from a rotational speed sensor 15 is input to the control means 13 (control unit). 1 and the second actuator 11 and 12, the intake passage area is synchronized with the air column frequency of the intake passage 3 and the period of the intake period based on the engine rotation speed, and the intake inertia effect is maximized. (Preferably, as the engine speed increases, open only the first on-off valve 8 in the low-speed range, open the second on-off valve 9 in the medium-speed range, and open both on-off valves in the high-speed range. 8.9.

In the figure, C116 is an intake valve, 17 is a cylinder block, and 18 is a piston.

Control of the intake passage area by switching the intake passages 3a and 3b according to the engine speed by the control means 13
The opening degrees of the first and second on-off valves 8 and 9 are shown in FIG.

When the engine rotation speed reaches the first set rotation speed N1, the first on-off valve 8 is closed by 1, while the second on-off valve 9 is opened, and the second set rotation speed is set to a value larger than the first set rotation speed N1. When the number N2 is reached, the first opening valve 8 is opened again.

Therefore, in the low rotation range below the first set rotation speed N1, the first
While intake air is supplied by only the intake passage 3a with a small intake passage area, in the middle rotation range exceeding the first set rotation speed N1 and below the second set rotation speed N2, the second intake passage 3b
In the high rotation range exceeding the second set rotation speed N2, the intake passage area is large due to both the first intake passage 3a and the second intake passage 3b. The area of the passage is controlled in three stages to supply intake air.

Note that the opening/closing valve 8 at the set rotational speeds N1 and N2 mentioned above.
In the switching control 9, since a shock occurs if the opening and closing are performed suddenly, it is preferable to perform the operation control so that the opening and closing are performed gradually or there is an overlap period.

According to the above control, as shown in FIG. 4, the full-open torque characteristics with respect to engine rotational speed fluctuations are as follows: curve ■ when intake air is supplied only by the first intake passage 3a, and curve ■ when intake air is supplied only by the second intake passage 3b. Curve ■ and curve ■ when intake air is supplied to both the first and second intake passages 3a and 3b.

■, ■ correspond to the tuning peak of the inhalation inertia effect, and increase and decrease,
The set rotational speed Nl at which the on-off valves 8 and 9 are switched at the point in time when each curve shows a larger torque than the other curves.

This is set to N2.

Therefore, in J5 of the above embodiment, since the passage area is changed in three stages and C is varied, a large intake inertia effect can be obtained at each stage, and the exit horn can be improved. Particularly, it is possible to effectively increase the output direction in a high rotation range where an intake inertia effect is required.

In addition, in the low rotation range C, combustion performance can be improved by reducing the intake passage area and improving the intake flow velocity in the comb-C, and in the high rotation range C, the intake passage area is large and a large amount of intake air can be supplied satisfactorily. be able to.

In addition, in the above embodiment, the first and second intake passages 3a,
A part of the partition wall 7 that separates the intake passages 3b and 3b is removed to create communication between the two.
a and 3b may be formed completely independently. In this case, the natural frequency of the intake system will change slightly.

Alternatively, a single intake port may be opened in the combustion chamber 2, and the intake passage upstream of this intake port may be divided into a first intake passage and a second intake passage.

[Brief explanation of the drawing]

Fig. 1 is a sectional front view of essential parts of an engine having an intake system according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line n-II in Fig. 1, and Fig. 3 shows an example of control characteristics. Explanatory diagram, Figure 4 shows the engine speed and full throttle 1 based on the control shown in Figure 3.
It is a characteristic diagram showing the relationship with Herc. 1...Engine 3...Intake passage 3a
......First intake passage 3b...Second intake passage 5...Surge tank 8...First
On-off valve 9...Second on-off valve 10...Switching means 11.12...Actuator 13...
・・・Control means

Claims (1)

[Claims] (1) The intake passage leading to the cylinder is formed at least in part by a first intake passage with a small passage area and a second intake passage with a large passage area, and the first intake passage and the second intake passage are independent from each other. A switching means is provided which has first and second on-off valves that open and close in response to an increase in engine speed.
Only the υJ valve is equipped with a control means that operates the switching means to open the first and second on-off valves in a high rotation range, and the intake passage area is switched in three stages. Engine intake system.