JP2995200B2 - Engine air supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air supply device for supplying air to an engine, particularly a multi-cylinder engine.

[Prior Art] When air flows into a cylinder when an air supply valve of an engine is opened, the inflow air has a certain inertia due to its mass and speed, and the inertia causes the piston to reach a bottom dead center. The flow continues even after the cylinder volume has ceased to increase, but when the piston starts to move upward, the pressure in the cylinder increases and the flow velocity of the inflowing air rapidly decreases to zero, and the inflow speed becomes zero. It is well known that the maximum charging efficiency is obtained by closing the air supply valve when the pressure in the cylinder is at a maximum. In addition, the inertia effect of the air flowing in the air supply pipe increases as the engine rotation speed increases, so the rotation speed range where the maximum filling efficiency is obtained is limited. The flow rate of the inflowing air becomes zero early and starts backflow before the intake valve closes, lowering the charging efficiency. It is also well known that the valve closes and reduces the filling efficiency.

The reason why the torque curve of the engine has a low mountain shape in the low speed and high speed regions is due to the above-described charging efficiency characteristic. In order to improve this characteristic and obtain a high torque in the entire engine speed range, In order to obtain a high filling efficiency in the region, the variable air supply system which divides the air supply pipe into two systems of low speed and high speed which are connected to the cylinder independently of each other and switches between them according to the rotational speed is used in some variable air supply systems. Used in engines.

However, the conventional variable air supply system including the low-speed air supply pipe and the high-speed air supply pipe has two branches of the intake manifold and has a large intake pipe volume downstream of the throttle valve. The backflow of burned gas in the cylinder to the air supply pipe is large at the time of no load or partial load when the inside of the air supply pipe is at a high negative pressure at the opening degree. Therefore, the ratio of fresh air to the burned gas flowing into the cylinder in the suction process becomes small, causing problems such as instability of idling and failure of partial load operation.

[Problem to be Solved by the Invention] The problem to be solved by the present invention is that the variable air supply system in which the air supply pipe is divided into two systems for low speed and high speed to expand the high torque region is used when no load is applied and The point is that the engine operating performance is reduced at the time of partial load.

That is, the present invention is intended to obtain good engine operability under no load and partial load in the variable air supply system. In the present invention, in addition to the expansion of the high torque region and the improvement of the operation stability in the light load region, the improvement of the fuel efficiency by the variable swirl is measured by utilizing the two supply pipes.

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

That is, the intake manifold branches into a low-speed supply pipe and a high-speed branch pipe, and these further branch into a low-speed supply branch pipe and a high-speed supply branch pipe for each cylinder of the engine, and are separately connected to the cylinders. In addition, the low-speed air supply branch pipe and the high-speed air supply branch pipe for each cylinder were connected to each other 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 air supply control valves realize a variable inertia effect, that is, expansion of a high torque region, and a variable air supply tube volume, that is, improved drivability in a light load region. It is to achieve improvement.

It is preferable that the low-speed air supply branch pipe be smaller in diameter and longer than the high-speed air supply branch pipe, and that two air supply control valves be simultaneously opened and closed.

[Operation] In the light load region, the first and second air supply control valves and the swirl control valve are closed regardless of the rotational speed of the engine, so that air is supplied to the cylinder only by the low-speed air supply branch pipe. The inflow creates a strong swirl and reduces the intake air volume. In the low-speed and high-load region, 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 the charging efficiency. In the high-speed and high-load region, the first and second air supply control valves and the swirl control valve are opened to further increase the air flow rate and obtain high filling efficiency.

Example An example of the present invention will be described with reference to the drawings.

Throttle valve 7 that controls the output (rotational speed) of engine 1 by controlling the flow rate of air that has passed through an air cleaner (not shown).
Downstream of the throttle body 8 with the intake manifold 9
Is connected. The cylinder 2 of the engine 1 has a low-speed port 3 and a high-speed port 5 independent of each other, and is opened and closed by intake valves 4 and 6 respectively.

The intake manifold 9 has a low-speed air supply pipe 10 and a high-speed air supply pipe 12
These branches 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 port 3 and a high-speed port 5. Low-speed supply branch 11
Are formed to have a smaller diameter and a larger length than the high-speed air supply branch pipe 13, and are connected to each other by a communication passage 14 for each cylinder 2 at a location near the engine 1.

Also, the high-speed air supply pipe, which is an aggregation of the high-speed air supply branch pipes 13,
A first air supply control valve 15 is installed in the vicinity of the inlet 12 and a second air supply control valve 17 is provided upstream and downstream of a connection point of the high-speed air supply branch pipe 13 with the communication passage 14. And a swirl control valve 19. These control valves 15, 17, 19
Is a butterfly and has a second air supply control valve 17 and a swirl control valve 19
Are attached to the single valve shafts 18 and 20, respectively, so as to open and close simultaneously. 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 opened and closed by an electromagnetic actuator 22 having an electromagnet. . The valve shaft 20 of the swirl control valve 19 is driven to open and close by a negative pressure type actuator 23 having a diaphragm, and is closed in a light load region where the intake manifold negative pressure is high, but is opened in a high load region where the intake manifold negative pressure is low. Performing the swirl control is the same as the conventional one. Actuators for air supply control valves 15, 17
Reference numeral 22 simultaneously opens and closes the two air supply control valves 15 and 17 in response to a drive signal sent from a microcomputer mounted on an automobile.

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

In the present embodiment configured as described above, in the light load range, the first and second air supply control valves 15 and 17 are closed regardless of the rotation speed of the engine 1, and the swirl control valve 19 Is closed by high intake manifold negative pressure.
At this time, all the air that has passed through the low-opening throttle valve 7 enters the low-speed air supply pipe 10 and passes from the low-speed air supply branch pipe 11 to the low-speed port 3.
Through the cylinder 2 at a high speed to generate a strong swirl to promote combustion. Also, two air supply control valves 1
Since the valves 5 and 15 are closed, the intake manifold 9
Reduces the effective flow area of the burned gas in the cylinder 2 so as to reduce the reverse flow rate of the burned gas, and does not deteriorate the operation performance especially in the low-speed rotation range (see FIG. 2).

Next, in the high load region, the swirl control valve 19 is opened by the intake manifold negative pressure being reduced.

Here, in the low speed and high load range, the first and second air supply control valves 1
The valves 5 and 17 are closed.
All of the air that has passed through enters the low-speed air supply pipe 10, passes through the low-speed air supply branch 11, passes through the low-speed port 3, and some of the air passes through the communication passage 14, and the high-speed air supply branch 13 and the high-speed port 5 And flows into the cylinder 2. That is, since the air flows through the two intake valves 4 and 6, the resistance is smaller and the air flow rate can be increased as compared with the case of only one intake valve, and the inertia effect of the small-diameter and long low-speed air supply branch pipe 11 is used. To obtain high filling efficiency. (See FIG. 3).

In the high-speed, 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, and the low-speed air supply branch pipe 11 and the high-speed air supply branch pipe 13 And flows into the cylinder 2 through the high-speed port 3 and the high-speed port 5. That is, air is supplied to the engine 1 in two systems. In particular, since the high-speed supply branch pipe 13 has a large diameter and a short diameter, a large amount of air flows to obtain high filling efficiency (see FIG. 4).

The actuators 22 and 23 may both be of an electromagnetic type, or may be constituted by a stepping motor so as to open and close in a stepless manner.
Each of the actuators 5 and 17 may be simultaneously opened and closed by a separate actuator.

[Effects of the Invention] As is clear from the above description, according to the present invention, in addition to the swirl control valve, the first air supply control valve is provided in the high-speed air supply pipe, and the second high-speed air supply branch pipe is provided in each high-speed air supply branch pipe. The air supply control valves are provided so that they are closed except in the high-speed, high-load range to generate strong swirl in the light-load range to promote combustion and to reverse the burned gas. In addition to reducing the flow rate and not only lowering the engine operation performance especially in the low-speed rotation range, it is also possible to open and close the air supply control valve according to the rotation range in a high load range to increase the filling efficiency and expand the high torque range. it can.

[Brief description of the drawings]

FIG. 1 is a sectional layout view 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, 11… low-speed air supply branch pipe, 12… high-speed air supply pipe, 13… high-speed air supply branch pipe, 14… communication path, 15… One air supply control valve, 17 ... second air supply control valve, 19 ... swirl control valve, 22, 23 ... actuator

Claims (3)

(57) [Claims] An intake manifold branches into a low-speed supply pipe and a high-speed branch pipe, and these branch into a low-speed supply branch pipe and a high-speed supply branch pipe for each cylinder of the engine. And the low-speed air supply branch pipe and the high-speed air supply branch pipe for each cylinder are connected to each other by a communication passage, and the high-speed air supply pipe is firstly connected near the inlet. The high-speed air supply branch pipe further includes a second air supply control valve and a swirl control valve on the upstream and downstream sides of the communication passage. apparatus. 2. The engine air supply device according to claim 1, wherein the low-speed air supply branch pipe has a smaller diameter and a longer length than the high-speed air supply branch pipe. 3. An air supply system for an engine according to claim 1, wherein said first and second air supply control valves are simultaneously opened and closed.