JPH04116226A - Air intake device of engine - Google Patents

Abstract

PURPOSE:To attain satisfactory engine operability under a no load or a partial load condition by providing a first intake control valve on a high speed intake pipe other than a swirl control valve, and providing a second intake control valve on each of high speed intake branch pipes. CONSTITUTION:An intake manifold 9 is branched to a low speed intake pipe 10 and a high speed intake pipe 12, and further branched to respectively low speed intake branch pipes 11 and high speed intake branch pipes 13 which are connected to respective cylinders 2. In respect to every cylinder 2, the low speed intake branch pipe 11 is communicated with the high speed intake branch pipe 13 through a communication passage 14. The high speed intake pipe 12 has a first intake control valve 15 in the vicinity of an inlet, while the high speed intake branch pipes 13 have each a second intake control valve 17 on an upstream side of the communication passage 14. Strong swirl is thus generated by opening the intake control valves 15, 17 under a high speed and load area, while a counterflow amount of combusted gas is reduced. Satisfactory engine operability is attained under a no load or a partial load condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air supply device for supplying air to an engine, particularly a multi-cylinder engine.

[Prior Art] When the intake valve of an engine opens and air flows into the cylinder, the incoming air has mass and speed, so it has a certain inertia, and this inertia causes the piston to reach the bottom dead center and move into the cylinder. The inflow of air continues even after the volume has stopped increasing, but when the piston begins to move upward, the pressure inside the cylinder increases and the flow velocity of the inflow air rapidly decreases to zero.
It is well known that the maximum filling efficiency can be obtained by closing the intake valve when the inflow velocity is zero and the cylinder pressure is maximum. In addition, the inertia effect of the air flowing in the intake pipe increases as the engine speed increases, so the rotation speed range where maximum charging efficiency can be obtained is limited, and the inertia effect is smaller at lower speeds than that. The incoming air quickly reaches zero flow velocity and begins to flow backwards before the intake valve closes, reducing filling efficiency. It is also well known that valves close and reduce filling efficiency.

The reason why the engine torque curve has a low mountain shape in the low speed and high speed ranges is due to the charging efficiency characteristics mentioned above.In order to improve this characteristic and obtain high torque over the entire engine speed range, In order to obtain high filling efficiency in the area,
Some engines employ a variable air supply system in which the air supply pipes are connected to cylinders independently of each other and are switched between two systems, one for low speed and one for high speed, depending on the rotational speed.

However, in the conventional variable air supply system that includes a low-speed air supply pipe and a high-speed air supply pipe, the intake manifold has two branches and the volume of the air supply pipe downstream of the throttle valve is large. When there is no load or partial load when the air supply pipe has a high negative pressure due to the opening, the amount of burned gas inside the cylinder backflows into the air supply pipe. Therefore, the ratio of fresh air to the burnt gas flowing into the cylinder during the intake stroke becomes small, resulting in problems such as unstable idling and poor partial load operation. [Problems to be Solved by the Invention] The problem we are trying to solve is that the variable air supply system, which aims to expand the high torque range by dividing the air supply pipe into two systems, one for low speeds and one for high speeds, causes a decline in engine operating performance at no load and partial load. That is the point.

That is, the present invention aims to obtain good engine operability at no load and at partial load in a variable air supply system. In addition, the present invention takes advantage of the fact that there are two air supply pipes to expand the high torque range and improve driving stability in the light load range, as well as improve fuel efficiency through variable swirl.

[Means for Solving the Problems] The measures taken by the present invention to solve the above problems are as follows.

That is, the intake manifold is branched into a low-speed air intake pipe and a high-speed air intake pipe, and these are further branched into a low-speed air intake branch pipe and a high-speed air intake branch pipe for each cylinder of the engine, and each is connected to each cylinder separately. In addition, the low-speed air supply branch pipe and the high-speed air supply branch pipe for each cylinder were communicated through a communication passage. A first air supply control valve was provided near the inlet of the high-speed air supply pipe, and a second air supply control valve and a swirl control valve were provided on the upstream and downstream sides of the communication path of the high-speed air supply branch pipe. .

The first and second intake air control valves realize variable inertia effect, i.e. expansion of high torque range, and variable intake pipe volume, i.e. improve drivability in light load range. This is what makes improvement possible.

Note that it is preferable that the low-speed air supply branch pipe be made smaller in diameter and longer than the high-speed air supply branch pipe, and that the two air supply control valves be driven to open and close at the same time.

[Operation] By keeping the first and second air supply control valves and swirl control valve closed regardless of the engine speed in the light load range, air can be supplied to the cylinder only by the low-speed air supply branch pipe. to generate a strong swirl and reduce the volume of the air supply pipe. In the low-speed, high-load range, the first and second air supply control valves are closed and the swirl control valve is opened to increase the air flow rate and improve charging efficiency. In the high-speed, high-load range, the first and second air supply control valves and the swirl control valve are kept open to further increase the air flow rate and obtain high filling efficiency.

[Example] The present invention will be described in detail with reference to the drawings.

An intake manifold 9 is connected downstream of a throttle body 8 that includes a throttle valve 7 that controls the output (rotational speed) of the engine 1 by controlling the flow rate of air that has passed through an air cleaner (not shown).

The cylinder 2 of the engine 1 has a low-speed boat 3 and a high-speed boat 5 that are independent of each other, and each is opened and closed by an intake valve 4.6.

The intake manifold 9 includes a low-speed air supply pipe 10 and a high-speed air supply pipe 1
These branch into a low-speed air supply branch pipe 11 and a high-speed air supply branch pipe 13 for each cylinder 2, and are connected to a low-speed boat 3 and a high-speed boat 5. The low-speed air supply branch pipe 11 is formed to have a smaller diameter and longer than the high-speed air supply branch pipe 13, and is communicated with each other by a communication passage 14 for each cylinder 2 at a location close to the engine 1.

In addition, a first air supply control valve 15 is installed near the entrance of the high-speed air supply pipe 12, which is the collection point of the high-speed air supply branch pipe 13, and is connected to the communication path 14 of the high-speed air supply branch pipe 13. A second air supply control valve 17 and a swirl control valve 19 are installed upstream and downstream of the connection point. These control valves 15, 17, 19 are linear and the second charge air suppression valve 1
7 and the swirl control valve 19 each have one valve stem 18.
20 so that they open and close all at once. The valve shaft 16 of the first air supply control valve 15 and the valve shaft 18 of the second air supply control valve 17 are connected by a link mechanism 21, and are simultaneously driven to open and close by an electromagnetic actuator 22 having an electromagnet. . The valve shaft 20 of the swirl control valve 19 is a negative pressure actuator 2 having a diaphragm.
3, and is closed in a light load range where the intake manifold negative pressure is high, but opens in a high load range where the intake manifold negative pressure is low to perform swirl control, which is the same as in the conventional one. Actuator 2 of air supply control valve 15.17
2 opens and closes two air supply control valves 15 and 17 at the same time using a drive signal sent from, for example, a microcomputer installed in an automobile.

Note that the second air supply control valve 17 is provided close to the connection point with the communication path 14.

In this embodiment configured in this way, the first and second air supply control valves 1 are closed regardless of the rotational speed of the engine 1 in the light load range.
5.17 is kept closed, and the swirl control valve 19 is closed due to the high intake manifold negative pressure.

At this time, all the air that has passed through the throttle valve 7 with a low opening degree enters the low-speed air supply pipe 10, flows from the low-speed air supply branch pipe 11 through the low-speed boat 3, and flows into the cylinder 2 at high speed, creating a strong swirl. generates and promotes combustion. In addition, since the two air supply control valves 5.15 are closed, the effective volume of the intake manifold 9 is reduced, and the back flow of burned gas in the cylinder 2 is reduced to a small amount, especially in the low speed rotation range. Does not reduce operating performance (see Figure 2).

Next, in a high load range, the intake manifold negative pressure becomes low, so that the swirl control valve 19 is opened.

Here, in the low speed and high load range, the first and second air supply control valves 15
．． 17 is kept closed, and the throttle valve 7 has a high opening degree.
All the air that has passed through enters the low-speed air supply pipe 10 and passes through the low-speed air supply branch pipe 11 to the low-speed boat 3, and some of the air passes through the communication path 14 to the high-speed air supply branch pipe 13 and the high-speed boat 5. It flows into cylinder 2 through. That is, since the air flows through two intake valves 4.6, the resistance is smaller than when there is only one intake valve, and the air flow rate can be increased, and the inertial effect of the small diameter and long low-speed air supply branch pipe 11 is utilized. to obtain high filling efficiency (see Figure 3).

In addition, in the high speed and high load range, the first and second air supply control valves 15.
The air that has passed through the throttle valve 7 enters both the low-speed air supply pipe 10 and the high-speed air supply pipe 12.
Air flows into the cylinder 2 from the low-speed air supply branch pipe 11 and the high-speed air supply branch pipe 13 through the low-speed boat 3 and the high-speed boat 5. That is, air is supplied to the engine 1 through two systems, and in particular, the high-speed air supply branch pipe 13 has a large diameter and is short and short, so that a large amount of air flows through it and high filling efficiency is obtained (see FIG. 4).

The actuators 22 and 23 may both be electromagnetic type or may be configured with a stepping motor to open and close the valves steplessly, and the first and second air supply control valves 15 and 17 may be operated separately. The actuators may be used to open and close the door at the same time.

[Effects of the Invention] As is clear from the above description, according to the present invention, in addition to the swirl control valve, the high-speed air supply pipe is provided with a first air supply control valve, and each high-speed air supply branch pipe is provided with a second air supply control valve. By setting these valves to remain closed except in high-speed, high-load ranges, a strong swirl is generated in light-load ranges to promote combustion and reduce the amount of burnt gas. It not only reduces the backflow flow and does not deteriorate engine performance, especially in the low speed rotation range, but also increases charging efficiency and expands the high torque range by opening and closing the air supply control valve according to the rotation range in the high load range. I can do it.

[Brief explanation of drawings]

FIG. 1 is a sectional layout diagram showing an embodiment of the present invention, and FIGS. 2, 3, and 4 are partial views for explaining the operation. 1...engine, 2...cylinder, 7...throttle valve,
9...Intake manifold, 10...Low speed air supply pipe, 1
1...Air supply branch pipe for low speed, 12...Air supply pipe for high speed, 1
3...High-speed air supply branch pipe, 14...Communication path, 15...
-First air supply control valve, 17...Second air supply control valve, 1
9... Swirl control valve, 22.23... Actuator,

Claims (1)

[Claims] 1. The intake manifold branches into a low-speed air supply pipe and a high-speed branch pipe, and these branch into a low-speed air supply branch pipe and a high-speed air supply branch pipe for each cylinder of the engine. The low-speed air supply branch pipe and the high-speed air supply branch pipe for each cylinder are connected to each other through a communication passage, and the high-speed air supply pipe is connected to the cylinder near the inlet. an engine comprising a first air supply control valve, and the high-speed air supply branch pipe includes a second air supply control valve and a swirl control valve on the upstream side and downstream side of the communication passage. air supply device. 2. The engine air supply system according to claim 1, wherein the low-speed air supply branch pipe has a smaller diameter and is longer than the high-speed air supply branch pipe. 3. The engine air supply system according to claim 1, wherein the first and second air supply control valves are driven to open and close simultaneously.