JP3384085B2 - Internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an internal combustion engine having a swirl control valve. [0002] As an internal combustion engine equipped with a Related Art swirl control valves, it has been known as disclosed in JP-JitsuHiraku 60-45829. [0003] This is a swirl control upstream of the intake port.
By installing a roll valve and closing the swirl control valve during low-speed and low-load operation of the internal combustion engine to reduce the cross-sectional area of the passage, the intake air velocity in the port is locally increased to generate swirl in the combustion chamber. To improve fuel efficiency and reduce emissions during cold weather. [0004] The conventional intake control system for an engine using such a swirl control valve has the following problems. Namely, although the HC by the combustion acceleration effect of the swirl control valve is reduced, a swirl control for example the cold time of the original mass of HC is discharged
The effect of the valve alone is not enough.
Reductions need to be made. [0006] For this purpose, a method of keeping the burned gas at a high temperature to promote the oxidation of unburned HC can be considered. For example, the opening timing of the exhaust valve is delayed to reduce the time for the burned gas to stay in the combustion chamber. It should be longer. It is also possible to make the closing timing of the exhaust valve earlier so that unburned HC scraped up and discharged from the clevis portion between the cylinder liner wall surface and the piston is sealed in the combustion chamber and not discharged to the exhaust pipe. It is effective for reduction. However, if the opening timing of the exhaust valve is delayed or the closing timing of the exhaust valve is advanced or both are performed in the entire operation range, a large amount of intake air is required and the swirl control valve cannot be used. Under such conditions of high speed and high load, exhaust is not sufficiently performed, and there is a problem that pumping loss due to exhaust extrusion work increases and output decreases. On the other hand, as an internal combustion engine provided with means for variably controlling the opening / closing timing of an intake valve or an exhaust valve, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. 4-194330. In this method, the timing of the exhaust valve is changed in accordance with the operation state of the internal combustion engine by switching a plurality of cams having different timings. By delaying the start time, the retention time of the burned gas in the combustion chamber is maintained long to promote the warm-up of the engine. [0010] However, the variable valve mechanism of this conventional type and not of the technical idea of controlling the opening and closing timing of the exhaust valve assumes the use of a swirl control valve, therefore if the swirl control
Even if a valve is applied, there is a problem that the output may decrease due to the pumping loss described above depending on the operation state. The present invention has been made based on such knowledge, and has as its object to reduce the amount of unburned HC emissions by controlling the opening and closing timing of an exhaust valve according to the opening and closing state of a swirl control valve. I have. According to the present invention, there is provided a swirl control valve for partially closing an engine intake port only in a low-speed and partial-load operation range, and an opening and closing timing of an exhaust valve. A variable valve mechanism that controls the exhaust valve opening start timing of the exhaust valve when the swirl control valve is closed compared to when the swirl control valve is open or when the exhaust valve is opened. At least one of the settings for making the valve closing completion timing earlier is always performed . In the partial load operation range where the swirl control valve is closed, such as low speed, low to medium load, etc., by delaying the start timing of opening the exhaust valve, the time during which the burned gas stays in the combustion chamber is extended. Therefore, the amount of unburned HC decreases. In addition, in the partial load operation range, by closing the exhaust valve earlier, the unburned HC that is scooped up from the clevis portion and is discharged to the outside is contained in the combustion chamber, so that the discharge is suppressed. You. On the other hand, in an operation region other than the above, that is, in a region where the intake air amount is large and the swirl control valve is opened, the exhaust valve starts opening relatively early, or closes the valve at a later time to exhaust the exhaust gas. Since the period for the stroke is long, there is no loss for exhaust extrusion, and good output and fuel economy performance is exhibited. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. First, the configuration will be described. 1 is a cylinder of an internal combustion engine, 2 is an intake port, and 3 is an exhaust port. Reference numeral 4 denotes an injector provided so as to face the intake port 2, and the amount of fuel calculated by the control unit 5 is injected and supplied through the injector 4. The control unit 5 receives signals from the engine speed sensor 21, the suction negative pressure sensor 22, the air flow meter 23, the water temperature sensor 24, the throttle opening sensor 25, and other signals indicating the engine operating state. Determines the operating state based on these signals, and controls the injector 4 and the actuator 9 described later so as to correspond to the operating state. A swirl control, which is opened and closed by an actuator 9 such as a diaphragm device, is provided at the intake port 2 so as to be located upstream of the injector 4.
A tool valve 10 is interposed. The control unit 5 drives a solenoid valve 11 that opens and closes an operation negative pressure to the actuator 9 to control swirl.
The open / close position of the valve 10 is controlled. The intake valve 12 and the exhaust valve 13 open and close the intake port 2 and the exhaust port 3, respectively, and are driven by an intake cam mechanism 14 and an exhaust cam mechanism 15, respectively. The exhaust side cam mechanism 15 is composed of two types of cams 15a and 15b having different lift curves, and a variable valve mechanism 16 selectively selects one of the cams 15a and 15b according to a control signal from the control unit 5. By switching, the opening / closing timing of the exhaust valve 13 is changed. Next, the operation will be described. FIG. 2 shows a swirl control according to this embodiment.
4 shows a flowchart relating to rule valve control. First,
The engine speed Ne and the suction negative pressure Boost are read, and it is determined whether the operating state of the engine is in a low speed and low to medium load range. When it is determined that the vehicle is in the low speed and low to medium load range, the swirl control valve is closed, and in other operating states, the swirl control valve is opened. FIG. 3 shows a flowchart relating to the valve timing control of this embodiment. First, the control unit 5 receives a signal for controlling the solenoid valve 11 and detects the open / closed state of the swirl control valve 10. When the swirl control valve open state is detected, the valve timing when the swirl control valve is open is selected, and the swirl control valve is selected.
Swirl control when a closed valve is detected
Select the valve timing when the valve is closed. Finally, the selected valve timing is output to the variable valve mechanism 16, and the valve timing is switched. FIG. 4 shows an example of a valve timing switching pattern when the swirl control valve is opened and closed. The left side of the figure corresponds to the exhaust valve, and the right side corresponds to the lift curve of the intake valve. In the example of this figure, the swirl control
When the valve is closed, the exhaust valve selects the opening / closing timing indicated by the broken line. This is because the exhaust valve closing completion timing is earlier than the opening / closing timing of the exhaust valve when the swirl control valve is opened, that is, the timing indicated by the solid line. By doing so, it is possible to prevent the unburned HC scraped up from the clevis portion from being discharged to the outside of the combustion chamber just before the end of the exhaust stroke, and to reduce the discharged HC. FIG. 5 shows the relationship between the crank angle of the engine and the amount of exhausted HC. As shown in FIG.
There are emission peaks. The peak near the exhaust valve closing completion timing is due to unburned HC scraped from the cylinder liner wall as described above, and the peak near the exhaust valve opening start timing is due to unburned HC in the burned gas. is there. Therefore, the opening / closing timing of the exhaust valve for reducing HC is not limited to the example shown in FIG.
The pattern as shown in FIG. 6 or FIG. 7 may be used.
FIG. 6 shows that the exhaust valve opening start timing is delayed when the swirl control valve is closed, and the burned gas stays at a relatively high temperature for a relatively long time even after combustion because the residence time of the burned gas in the combustion chamber is increased. The oxidation of unburned HC is promoted, and the amount of exhaust HC is reduced. FIG. 7 shows that the exhaust valve opening start timing is delayed and the valve closing completion timing is advanced, and both effects can further reduce HC. By the way, generally, when the exhaust valve opening start timing is delayed or the exhaust valve closing completion timing is advanced, the valve opening period is relatively short in a high-speed region, and the amount of gas that can be discharged decreases. The output and fuel consumption are reduced due to the increase in exhaust extrusion work. However, in the present invention, the swirl control bar under high speed and high load conditions is used.
When the valve 10 is opened, the exhaust valve opening / closing timing is also normal, that is, the opening timing of the exhaust valve is delayed,
Since the control for shortening the valve closing completion time is not performed, a sufficient valve opening period can be secured, and deterioration of output and fuel efficiency caused by pumping loss in this region can be avoided. FIG. 8 shows a second embodiment of the present invention, in which an EGR device (exhaust gas recirculation device) is added to the configuration of the first embodiment. That is, in the drawing, the control unit 5 controls the opening degree of the EGR control valve 7 provided in the middle of the EGR passage 6 which communicates the intake and exhaust systems of the internal combustion engine with each other via the actuator 8 according to various operating states. It has a configuration. In the partial load region after the engine is warmed up, EGR may be performed as a means for reducing NOx and fuel consumption. At this time, if a swirl control valve is used in combination, deterioration of combustion due to recirculated gas is suppressed, and from the viewpoint of drivability. It is possible to perform a large amount of EGR, but if the EGR is performed, the unburned HC increases, and therefore the large amount of EGR cannot always be performed in consideration of the emission. However, in this case, if the valve timing control of the present invention is used, the swirl control valve
The exhaust HC reduction effect of the valve timing during blanking used it is possible to suppress an increase in exhaust HC,
This can offset the increase in HC due to EGR,
It is possible to simultaneously improve fuel efficiency and emission by using a large amount of EGR. FIG. 9 shows a flow chart of the EGR control in this embodiment. First, the engine speed Ne and the suction negative pressure Bo
ost and the cooling water temperature Tw are read, and when it is determined that the cooling water temperature Tw is equal to or higher than a predetermined value and the engine is warmed up, Ne and Boos are determined.
The target EGR amount according to t is calculated by the control unit 5, and the EGR control valve 7 is controlled to obtain an optimal EGR amount. In this embodiment, the swirl control is also performed.
The control of the valve 10 and the control of the valve timing of the exhaust valve 13 are performed in the same manner as in the first embodiment. Therefore, in the partial load area after engine warm-up, the swirl control
Since the trawl valve 10 is closed, and the exhaust valve opening / closing timing is late opening and / or early closing, either, a large amount of EGR can greatly improve fuel efficiency and emission. As described above, according to the present invention, a swirl control valve and a variable valve mechanism are provided in an internal combustion engine, and a low-speed and partial-load swirl control valve which does not require relatively high output is provided. In the closed operating region, the swirl control
HC in the burned gas is slower than when the valve is open.
Promotes the oxidation of the exhaust gas or accelerates the closing of the exhaust valve to confine the unburned HC scooped up from the clevis in the combustion chamber, or both, and otherwise operates the swirl control valve in the open state. in since to perform the valve timing control to the normal exhaust valve opening and closing timing, without causing deterioration of the output and fuel consumption in the swirl control valve nonuse region, swirl
The effect that the exhaust HC can be reduced in the control valve use region can be obtained. Further, by applying the present invention to an internal combustion engine provided with an EGR device, there is obtained an effect that a large amount of EGR can be performed without impairing drivability to further improve fuel efficiency and emission.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention. FIG. 2 is a flowchart showing control contents of a swirl control valve according to the first embodiment. FIG. 3 is a flowchart showing control contents of valve timing according to the first embodiment. FIG. 4 is a swirl control bar according to the first embodiment.
FIG. 4 is a characteristic diagram showing a valve timing switching pattern when a lube is opened and closed. FIG. 5 is a characteristic diagram showing a relationship between an exhaust valve operating period and an amount of HC emission. FIG. 6 is a characteristic diagram of another example of a valve timing switching pattern when the swirl control valve is opened and closed. FIG. 7 is a characteristic diagram of another example of a valve timing switching pattern when the swirl control valve is opened and closed. FIG. 8 is a schematic configuration diagram of a second embodiment of the present invention. FIG. 9 is a flowchart showing the control contents of EGR of the second embodiment. [Description of Signs] 1 cylinder 2 intake port 3 exhaust port 4 injector 5 control unit 6 EGR passage 7 EGR control valve 8 EGR actuator 9 swirl control valve actuator 10 swirl control valve 11 swirl control valve control solenoid 12 intake valve 13 exhaust Valve 14 Intake side cam 15 Exhaust side cam 16 Variable valve mechanism 21 Rotation speed sensor 22 Intake negative pressure sensor 23 Air flow meter 24 Water temperature sensor 25 Throttle opening sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 43/00 F02D 43/00 301Z

Claims (1)

(57) [Claim 1] A swirl control valve that partially closes an engine intake port only in a low speed and partial load operation range, and a variable valve mechanism that controls opening and closing timing of an exhaust valve. And wherein the variable valve mechanism sets the exhaust valve opening start timing later or the exhaust valve closing completion timing earlier when the swirl control valve is closed compared to when it is open. An internal combustion engine wherein at least one of the settings is always set.