JPH0362888B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake control method for a variable intake swirl type internal combustion engine used in vehicles such as automobiles, and more specifically relates to a method for controlling intake air flow at an intake port. The present invention relates to an intake control method for a variable intake swirl type internal combustion engine having an intake control valve that performs the following.

[Prior Art] An internal combustion engine with a variable intake swirl system has a helical passage that swirls around an opening end to a combustion chamber, and a straight passage that linearly communicates with the opening end. An internal combustion engine having an intake port structure in which an intake control valve for opening and closing the straight passage is provided in the middle of the
57-165629 and JP-A-58-23224. In an internal combustion engine equipped with this type of intake port structure, when the straight passage is closed by the intake control valve, almost all of the intake air (air mixture) flows into the combustion chamber through the helical passage. This creates a relatively strong intake swirl within the combustion chamber, which increases the apparent fire propagation speed within the combustion chamber and increases the combustion rate.
Operation with a lean air-fuel mixture, that is, lean combustion operation, becomes possible.On the other hand, when the intake control valve opens the straight passage, the intake air flows through the straight passage in addition to the helical passage and flows into the combustion chamber. Although no strong intake air swirl occurs within the combustion chamber, the flow resistance to intake air flow through the intake port remains low, increasing the charging efficiency of the internal combustion engine.

Conventionally, in an internal combustion engine having the above-described intake port structure, the intake control valve is closed during low to medium load operation and opened during high load operation, depending on the throttle opening or intake pipe negative pressure. As a result, in the low to medium load operating range when the intake control valve is closed, the air-fuel ratio is 22.
It is possible to perform lean combustion operation with a lean mixture of about ~18%, improving fuel economy, and in high-load operating ranges when the intake control valve is open.
Although it is not possible to operate with a lean air-fuel mixture having a large air-fuel ratio as described above, it is now possible to obtain a large engine output by increasing the charging efficiency of the internal combustion engine.

[Problem to be solved by the invention] However, in internal combustion engines, even during low to medium load operation, as when warming up the engine, the air-fuel mixture is not lean but at or below the stoichiometric air-fuel ratio. It is sometimes preferable to operate with an air/fuel mixture. This is because a strong intake swirl gives a strong cooling effect to the combustion chamber, and when the engine temperature has not risen sufficiently, such as during engine warm-up, the engine is cooled by the intake swirl. This is because the thermal efficiency decreases, and the fuel economy of the internal combustion engine decreases.

The present invention has focused on the above-mentioned circumstances, and an object of the present invention is to provide a method for more appropriately controlling an intake swirl control valve in an intake port of an internal combustion engine in order to improve fuel economy.

[Means for Solving the Problems] According to the present invention, the problem is solved by having a helical passage swirling around an opening end to the combustion chamber, and a straight passage linearly communicating with the opening end, In an intake control method for an internal combustion engine having an intake control valve disposed in the middle of a straight passage for opening and closing the straight passage, the intake control valve is opened when the engine load is equal to or higher than a predetermined value, and the intake control valve is opened when the engine load is at the predetermined value. The intake control valve for an internal combustion engine is characterized in that the intake control valve is closed when the engine load is below the predetermined value and the lean burn operation is being performed, and the intake control valve is opened when the engine load is below the predetermined value and the lean burn operation is not being performed. This is accomplished by a method.

[Operations and Effects of the Invention] As described above, when the engine load is below a predetermined value, it is determined whether or not to close the intake control valve to increase the intake swirl, and whether or not the engine is in lean burn operation at that time. By performing control according to the intake swirl control, it is possible to further enhance the effect of improving the fuel economy of the engine based on the intake swirl control.

Note that idling operation is one of the engine operating states in which the engine load is below a predetermined value and the engine is not in lean burn operation. In this case, since combustion of the air-fuel mixture is performed better when intake swirl occurs during idling operation, intake swirl operation may be performed with the intake control valve closed at this time.

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

FIG. 1 shows one embodiment of an internal combustion engine of a variable intake swirl type in which the intake control method according to the present invention is implemented. In the figure, reference numeral 1 indicates an internal combustion engine main body, which includes a cylinder block 2, a cylinder head 3, a piston 5 provided in a cylinder bore 4 of the cylinder block 2, and an intake valve 6. A mixture of fuel and air is drawn into the combustion chamber 8 through the intake port 7 which is opened and closed by the ignition port 7, and the burnt gas of the mixture is ignited by the spark discharge of the spark plug 9 in the combustion chamber 8. The exhaust is discharged outside the combustion chamber through an exhaust port that is opened and closed by an exhaust valve.

The spark plug 9 is configured to discharge a spark by being supplied with current by a distributor 29, and the timing, that is, the ignition timing, is determined by the operation of an igniter 34 provided in an ignition coil device 33. It's summery.

As clearly shown in FIG. 2, the intake port 7 is formed to bulge out from the ceiling wall of the intake port 7 downward in the figure, leaving a predetermined gap between it and the bottom wall of the intake port 7. It has a guide vane 10, which divides the inside of the intake port 7 into a helical passage 11 that revolves around the opening end 7a leading to the combustion chamber 8, and a straight passage 12 that leads linearly to the opening end 7a. . An intake control valve 13 is provided in the middle of the straight passage 12 to open and close the straight passage. The intake control valve 13 is configured as a butterfly valve and is drivingly connected to a drive rod 17 of a diaphragm device 16 by a drive lever 15 mounted on a valve stem 14, as best shown in FIG. It is designed to be opened and closed by a device.

The diaphragm device 16 drives the intake control valve 13 to the closed position as shown in FIG. When a negative pressure greater than the value is not introduced, the intake control valve 13 is driven to an open position that establishes communication with the straight passage 12. Diaphragm device 16 is connected by conduit 18 to electromagnetic control valve 19.
is connected to port a of Solenoid control valve 19
has a negative pressure port b and an atmospheric pressure port c in addition to port a, and when the electromagnetic coil is energized, port a is connected to negative pressure port b, whereas when the electromagnetic coil is energized, port a is connected to negative pressure port b. When not in use, port a is connected to atmospheric pressure port c. Atmospheric pressure port c is open to the atmosphere,
On the other hand, negative pressure port b is connected to an intake pipe negative pressure outlet port 25 provided in a surge tank 24 of the engine intake system via a negative pressure pipe 20, a check valve 21, and a negative pressure pipe 22. are now being supplied.

An intake manifold 23 and a surge tank 24 are connected in this order to the intake port 7, and an air intake port of the surge tank 24 is provided with a throttle valve 26 for controlling the intake air flow rate. The intake manifold 23 is provided with a fuel injection nozzle 27, which is supplied with liquid fuel such as gasoline from a fuel supply device (not shown), and inhales the liquid fuel at a flow rate corresponding to the valve opening time. It is designed to be injected and supplied toward the inlet of port 7.

Control of energization to the electromagnetic control valve 19, that is, intake control, valve opening control of the fuel injection nozzle 27, that is, air-fuel ratio control, and ignition timing control are performed by the control device 30. The control device 30 is
It is an electrical control device that includes a microcomputer with a general structure, and it receives information about the engine speed from the distributor 29 of the engine ignition system, information about the intake pipe pressure P from the intake pipe pressure sensor 31, and receives information about the intake pipe pressure P from the intake pipe pressure sensor 31. 32, information regarding the throttle opening of the throttle valve 26 is provided, and according to this information and a predetermined program, the energization of the electromagnetic control valve 19, the opening control of the fuel injection nozzle 27, and the output to the igniter 34 are performed. It is designed to control signals.

Next, the implementation of the intake air control method according to the present invention will be explained with reference to the flowchart shown in FIG. The intake control routine of the flowchart shown in FIG. 3 is executed as a part of the main routine or as an interrupt routine that is repeatedly executed at predetermined time intervals.

In the first step 1, it is determined whether the opening Thr of the throttle valve 26 detected by the throttle opening sensor 32 is larger than a predetermined value Tset, for example 50 degrees. When Thr>Tset, the process proceeds to step 4, whereas when Thr>Tset does not hold, the process proceeds to step 2.

In step 2, it is determined whether the internal combustion engine is being operated with a lean air-fuel mixture having an air-fuel ratio greater than the stoichiometric air-fuel ratio, that is, whether it is in lean burn operation. If lean burn operation is in progress, proceed to step 5; on the other hand, if lean burn operation is not in progress, that is, if the engine is operated with a stoichiometric air-fuel ratio or an air-fuel mixture having an air-fuel ratio smaller than the stoichiometric air-fuel ratio, proceed to step 3. .

In step 3, the intake pipe pressure Pi is set to a predetermined value.
A determination is made as to whether Pset is greater than, for example, 260 mmHg. When Pi>Pset, that is, when the intake pipe negative pressure is smaller than a predetermined value, the process proceeds to step 4, where Pi>
When it is not Pset, that is, when the intake pipe negative pressure is larger than a predetermined value (during low load operation), the process proceeds to step 5.

In step 4, the electromagnetic control valve 19 is de-energized and the diaphragm device 16 opens the intake control valve 13.

In step 5, the electromagnetic control valve 19 is energized to cause the diaphragm device 16 to close the intake control valve 13.

By performing control according to the flowchart as described above, the intake control valve 13 is operated under medium load when the intake pipe negative pressure is smaller than the predetermined value even if the opening degree of the throttle valve 26 is below the predetermined value Tset. The valve will open unless lean burn operation is in progress. This reduces cooling losses without deteriorating the combustibility of the internal combustion engine, thereby increasing thermal efficiency and improving fuel economy.

In the above embodiment, the throttle opening is used as information representative of the engine load, but this may also be intake pipe negative pressure or other equivalent information.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited thereto, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a variable intake swirl type internal combustion engine used to implement the intake control method according to the present invention, and FIG. 2 is an intake port of the internal combustion engine shown in FIG. 1. FIG. 3, which is a schematic vertical sectional view showing the structure in an enlarged manner, is a flowchart of an intake control routine for carrying out the intake control method according to the present invention. 1...Internal combustion engine, 2...Cylinder block, 3
...Cylinder head, 4...Cylinder bore, 5...
Piston, 6...Intake valve, 7...Intake port, 8
... Combustion chamber, 9 ... Spark plug, 10 ... Guide vane, 11 ... Helical passage, 12 ... Straight passage, 13 ... Intake control valve, 14 ... Valve shaft,
15... Drive lever, 16... Diaphragm device, 17... Drive rod, 18... Conduit, 19...
... Solenoid control valve, 20 ... Negative pressure conduit, 21 ... Check valve, 22 ... Negative pressure pipe, 23 ... Intake manifold, 24 ... Surge tank, 25 ... Intake pipe negative pressure extraction port, 26 ... ...Throttle valve, 27...
Fuel injection nozzle, 28...exhaust manifold, 2
9...distributor, 30...control device,
31...Intake pipe pressure sensor, 32...Throttle opening sensor, 33...Ignition coil device, 34...Igniter.

Claims (1)

[Claims] 1. An internal combustion engine having a helical passage swirling around an opening end to a combustion chamber and a straight passage leading straight to the opening end, and an intake control valve that opens and closes the straight passage in the middle of the straight passage. In an engine intake control method, the intake control valve is opened when the engine load is above a predetermined value, and the intake control valve is closed when the engine load is below the predetermined value and lean burn operation is being performed; An intake control method for an internal combustion engine, characterized in that the intake control valve is opened when the engine load is below a predetermined value and the lean burn operation is not performed.