JPS60178933A - Supercharging pressure control device for exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To aim at retroactively obtaining a high output power to prevent an engine from knocking, by controlling the flow of exhaust gas led to an exhaust gas in accordance with the octane number of used fuel to obtain a desired supercharging pressure control value in accordance with the octane number. CONSTITUTION:A flap drive means mainly composed of a diaphragm device 22 and a solenoid valve 23 positionally controls a flap 21. A bypass drive means mainly composed of a diaphragm device 15, a solenoid 16, etc., controls a bypass valve 14. The solenoid valve 23 for the flap and the solenoid valve 16 for the bypass valve 16 are controlled to be opened and closed in accordance with an octane number map selected corresponding to the octane number of used fuel which is delivered from an octane number detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a supercharging pressure control device for an exhaust turbocharger that changes a control target value of supercharging pressure according to the octane number of fuel.

Background Art) An internal combustion engine with an exhaust turbocharger uses the exhaust energy of the internal combustion engine to rotationally drive an exhaust turbine, and uses a compressor rotated by the exhaust turbine to supercharge intake air to the internal combustion engine. It is known that since the intake air is supercharged to the internal combustion engine, the intake air filling efficiency is improved, and the amount of fuel supplied can be increased accordingly, which greatly contributes to the output direction. However, when the supercharging pressure becomes excessive, excessive stress acts on the internal combustion engine and its intake/exhaust system, leading to the risk of damage or breakage, or the occurrence of knocking.

Therefore, one of the preventive measures is, for example, U.S. Patent No. 2947
There is an exhaust flow rate control device found in the '86 specification. This system is equipped with a flap at the exhaust inlet of the exhaust turbocharger, and by adjusting the opening degree of the flap, the exhaust inlet flow velocity towards the exhaust turbine is controlled, and the exhaust flow velocity is increased in the engine low load rotation region. This increases the rotational speed of the compressor to increase the boost pressure, and in the high load region of the engine, increases the flap opening to reduce the exhaust flow velocity and prevent the exhaust turbine from overspeeding. Prevents excessive rise in supply pressure.

Another method is to provide a bypass passage that connects the upstream and downstream of the exhaust turbine, as seen in Japanese Patent Application Laid-open No. 57-108413, in which the boost pressure downstream of the exhaust turbine is set to a predetermined value or more. When the exhaust gas is about to rise, the bypass control valve device opens valve U7 to release the exhaust energy to the outside via the bypass passage without using it to rotate the exhaust turbine, thereby preventing the exhaust turbine from overspeeding. There are also known devices that prevent excessive increases in boost pressure.

According to these exhaust flow rate control devices, exhaust bypass control valve devices, etc., which control the flow of exhaust gas guided to the exhaust turbine to control the boost pressure, both controls reduce the boost pressure to the point where non-king occurs. The control target value is determined to set the pressure as high as possible within the range in which the output is maintained.

However, such control target values are set according to a specific type of fuel (for example, regular gasoline), so when using fuel with a higher octane number, supercharging may be lower than the set control target value. Although high output can be obtained by increasing the pressure, there is a problem in that the control target value is low and the characteristics of high octane fuel cannot be utilized.

Conversely, when using a lower octane fuel than the specific fuel, the control target value is set higher than the boost pressure at which knocking does not occur for this fuel, so non-king naturally occurs. This inconvenience arises.

<Object of the Invention> In view of the above-mentioned disadvantages of the conventional exhaust control device, the present invention controls the flow of exhaust gas guided to the exhaust turbine according to the octane number of the fuel used, thereby achieving a control target of boost pressure according to the octane number. It is an object of the present invention to provide a supercharging pressure control device for an exhaust turbocharger that obtains the highest possible output and prevents non-king.

<Structure of the Invention> For this purpose, in the present invention, as shown in FIG. 1, the octane number of the currently used fuel is detected by the octane number detection means,
The exhaust control valve is controlled by the control means according to the octane number and the value detected by the engine operating state detection means, thereby obtaining a target supercharging pressure corresponding to the octane number.

<Example> Embodiments of the present invention will be described below based on the drawings.

In the embodiment shown in FIG. 2, the intake air of the internal combustion engine l is supplied to the combustion chamber through an intake passage 2. In the embodiment shown in FIG. During this period, the air flow Qa of the intake air is measured by the air flow meter 3, the intake air is pressurized (supercharged) by the compressor 5 of the exhaust turbocharger 4, and the intake air is regulated by the intake throttle valve 6. Then, it is mixed with fuel injected from the fuel injection valve 7 and introduced into the combustion chamber, where it is combusted to obtain output. The engine rotation speed N at that time is detected by a rotation sensor 8 such as a crank angle sensor.

A pressure sensor 9 is provided in the intake passage 2 between the compressor 5 and the intake throttle valve 6 to detect supercharging pressure Ps.

On the other hand, the combustion exhaust discharged from the combustion chamber of the internal combustion engine 1 into the exhaust passage 11 rotates the exhaust turbine 12 of the exhaust turbocharger 4 and is discharged to the outside.

The exhaust turbine 12 is connected to the compressor 5 by a shaft 4a, and the rotation of the exhaust turbine 12 simultaneously drives the compressor 5 to rotate.

Here, the exhaust passage 11 is provided with a bypass passage 13 for guiding the exhaust gas by bypassing the exhaust turbine 12, and a bypass valve 14 for opening and closing the bypass passage 13 is interposed.

The bypass valve 14 includes a diaphragm device 15 and a solenoid valve 16.
Its rotation is controlled by a bypass valve driving means whose main elements are: That is, the bypass valve 14 is connected to the diaphragm 15a of the diaphragm device 15 via a link 15b, and the supercharging pressure downstream of the compressor 5 is transferred to the pressure working chamber 15c provided on one side of the diaphragm 15a.
7. A three-way switching type solenoid valve 16 is installed in the pressure passage 17, and the supercharging pressure in the pressure passage 17 is relieved to the atmosphere by opening the atmospheric boat 16a. The opening/closing time ratio of the bypass valve 16a is controlled to increase or decrease the pressure in the pressure working chamber 15C, and the opening degree of the bypass valve 14 is controlled via the diaphragm 15a. "Exhaust passage 11 between bypass valve 14 and turbine 12,
Preferably, a flap 21 is provided at the scroll inlet of the exhaust turbine 12 to control the exhaust flow rate. The flap 21
The upstream end of the exhaust turbine 12 is rotatably supported by a casing at the scroll inlet of the exhaust turbine 12, and the downstream end thereof swings to increase or decrease the inlet opening area of the exhaust turbine 12. Teru. If the aperture area increases (
The exhaust flow velocity decreases (indicated by the solid line at position b in the figure), and increases as the opening degree decreases (indicated by the dotted line at position a in the figure).

The position of the flap 21 is controlled by a flap drive means whose main components include a diaphragm device 22, a solenoid valve 23, and the like. That is, the diaphragm 24 of the diaphragm device 22
A flap 21 is connected to the diaphragm 24 via a link 25, and the supercharging pressure between the compressor 5 and the intake throttle valve 6 is transmitted to a pressure operating chamber 26 provided on one side of the diaphragm 24 via a pressure passage 27. be guided. A three-way switching electromagnetic valve 23 having an atmospheric boat 23a is installed in the pressure passage 27, and supercharging is introduced into the pressure working chamber 26 by controlling the time ratio of opening and closing the atmospheric boat 23a. Controls pressure increase/decrease.

The pressure in the upstream exhaust passage 11 of the flap 21 (exhaust pressure Pe) is detected by an exhaust pressure sensor serving as exhaust pressure detection means. In the figure, 6a is a throttle sensor that detects the opening degree θ of the intake throttle valve 6, and 28 is the internal combustion engine cooling water temperature T.
This is a water temperature sensor that detects W.

These fuel injection valves 7, electromagnetic valves 16 and 23 are connected to the pressure sensor 11-9, throttle sensor 6a, air flow meter 3, rotation sensor 8, water temperature sensor 28, which acts as an engine operating state detection means, and the water temperature sensor 28 (not shown). The command is controlled to an optimum value calculated by the control unit 30 based on various detection signals output from a starter switch or the like that detects the operation of the starter motor.

Further, the internal combustion engine 1 is provided with a knocking sensor 31 for detecting a knocking sensor.

In the above-mentioned embodiment, the exhaust control device that controls the flow of exhaust gas introduced into the exhaust turbine 12 includes a valve device that controls the flow rate of exhaust gas supplied to the exhaust turbine, that is, the flap 21, its driving means, and a bypass valve. 14 and its driving means have been disclosed, however, at least one of these may be used.

The control unit 30 is controlled as shown in FIG.

That is, the detection signals of the air flow meter 3 and the rotation sensor 8 are input to the intake air amount detection means 41 and the rotation speed detection means 42, where the intake air 1i1Qa and the engine rotation speed N are input.
is read and input to the injection pulse calculation means 43.

The injection pulse calculating means 43 calculates Tel in the basic injection pulse corresponding to the amount of fuel injected per engine rotation using the relational expression TP=-Qa/N, and the output signal thereof is input to the injection pulse correcting means 44. , here, various corrections are made to 'I''P during the basic injection pulse in response to inputs of the other engine operating status signals, such as throttle opening θ, engine cooling water temperature TL-1, starter inch on/off, etc. outputs an injector drive pulse to the injector drive means 45.The injector drive means 45 controls the opening/closing time ratio of the injector 7 according to the input injection pulse rp to achieve the optimum timing according to the engine operating state. The amount of fuel is injected and supplied.

The basic injection pulse rtJTP and engine rotation speed N are
The bypass valve control duty ratio setting means 46, the bypass valve control duty ratio setting means 52, and the octane number detection means 57 are inputted, respectively.

The flap control duty ratio setting means 46 reads out the control duty ratio from the memory 49 having a map assigned by the basic injection pulse TP and the engine rotational speed N, and uses the value as the driving means 47 of the flap solenoid valve 23.
Output to. The electromagnetic valve driving means 47 outputs a driving current with a set duty ratio to drive the flap electromagnetic valve 23.

The flap control duty ratio setting means 46 cannot read out the map, and the map shows the octane number of the fuel used, for example, 91 octane number to 9.
8 Multiple maps 48 stored in advance according to octane rating
81 to 4.8an, and the map selection means 46a selects and reads one of the maps corresponding to the octane number of the currently used fuel outputted from the octane number detection means 57.

For example, when the solenoid valve 23 is controlled with a duty ratio of 0%, the atmospheric port 23a is opened to release the pressure in the pressure passage 27 to the atmosphere, and the pressure in the pressure operating chamber 26 is reduced to open the link 25. Displace the intervening flap 21 to the dotted line position a in the figure to reduce the opening area of the inlet I of the exhaust turbine 12,
This increases the exhaust flow velocity and speeds up the rotation of the exhaust turbine 12. When the duty ratio is 10 oz, the solenoid valve 23 closes the atmospheric boat 23a and increases the pressure in the pressure working chamber 26.
The flap 21 is moved to the open position shown by the solid line via the diaphragm 24 to increase the inlet opening area of the exhaust turbine 12 to reduce the exhaust flow velocity and decelerate the rotation of the exhaust turbine 12.

Therefore, by controlling the control duty ratio of the electromagnetic valve 23, a desired valve opening degree of the flap 21 can be obtained, thereby freely controlling the exhaust gas flow rate supplied to the exhaust turbine 12 and the boost pressure according to the engine operating state. can do.

The bypass valve control duty ratio setting means 52 has a plurality of maps 53 corresponding to different fuel octane numbers assigned in advance based on the basic injection pulse width TP and the engine rotational speed N.
The control duty ratio is read from the memory 54 provided with a1 to 53an. In this case, in accordance with the octane number of the currently used fuel outputted from the octane number detection means 57, similarly to the flap control, the map selection means 52a selects and reads out one of the corresponding octane number maps 5381-53an. Then, the read value is output to the driving means 55 of the bypass valve solenoid valve 16 to control the time ratio of opening and closing of the atmospheric port 1-16a of the solenoid valve 16. Thereby, the valve opening degree of the bypass valve 14 is controlled in the same manner as in the case of flap control. If the opening degree of the bypass valve 14 increases, an exhaust flow is generated toward the bypass passage 13 without rotating the exhaust turbine 12, reducing the rotational energy of the exhaust turbine 12, preventing the compressor 5 from over-rotating, and supercharging. Can prevent excessive pressure rise.

In this way, the flap control duty ratio setting means 46, the memory 49, and the driving means 47 of the solenoid valve 23 constitute a flap control means, and the bypass valve control duty ratio setting means 52, the driving means 55 of the solenoid valve 16, and the memory 54 constitutes the bypass valve control means, and these as a whole constitute the flap 2
1 and a bypass valve 14 constitute a control means M of the exhaust control device.

Next, a specific example of the octane number detection means 57 is shown in the block diagram of FIG. 4, and its operation will be explained using the flow chart of FIG.

The octane number detection means 57 used in this embodiment uses an ignition advance control means 60 that controls the ignition circuit 59 of the engine. That is, the ignition advance control means 60 reads the basic ignition advance angle from the memory 63 based on the basic injection pulse TP and the engine speed N, and outputs it to the ignition advance change means 64.

The memory 63 has in advance a plurality of basic ignition advance angle manipulators 2a1 to 62an corresponding to the octane number of the fuel, one in the basic injection pulse and the engine rotational speed N, and is outputted from the octane number determining means 65, which will be described later. Basic ignition advance angle map 61a1 to 62 corresponding to the octane number of the currently used fuel
One of an is selected via the map selection means 61a.

By the ignition advance control means 60 having such a configuration, first 91
The basic ignition advance angle map 62a1 for octane is selected, and the ignition circuit 59 is controlled, and the flap control duty ratio setting means 46 and the bypass valve control duty ratio setting means 52 also use the map 48a for 91 octane.
1 and 53al to control the flap opening and bypass valve opening, respectively, to control the boost pressure (571)
.

When the engine is operated and warmed up under such operating conditions, the warm-up determining means 66 determines that warm-up is complete based on the engine cooling water temperature 'r4 outputted from the water temperature sensor 28 (572), and the determination start control means 67 determines this. Output.

In the judgment start control means 67, the basic injection pulse) 11
Based on T P and the engine rotational speed N, in S73 the engine rotational speed N is between 2.000 rpm and 4.00Orpm, and in S74 the basic injection pulse is 7 mn + 8 more than Fig. 6. It is determined that the octane number is in the octane determination zone Z shown in FIG. The octane number determination zone Z is in a high speed, high load operating state where non-king is likely to occur. When such an operating state is reached, the ignition advance changing means 64 and the octane number determining means 65 are notified of this, and the ignition advance changing means 64 changes the basic ignition advance (91 octane) output from the ignition advance control means 60 in S75. Advance the ignition advance angle by 4 degrees to correspond to the basic ignition advance angle for 93 octane (S75).
This is input to the octane number determining means 65. The octane number determination means 65 outputs a command signal to the map selection means 61a to the effect that the 93 octane map should be used, thereby reading the basic ignition advance angle of the 93 octane map from the corresponding map, and changing the ignition circuit 59 to the 93 octane map. Controlled by basic ignition advance angle. Then, in step 376, it is detected whether or not non-king is ordered under the ignition advance condition. When a non-king occurs, the knocking sensor 31 outputs this to the knocking level detecting means 68, and outputs this to the octane number determining means 65. If knocking occurs, it is determined that the selection of the basic ignition advance angle for 93 octane in the ignition advance control means 60 is an error, and it is determined that the currently used fuel is a fuel having an octane number of 91. . Then, in S78, a command signal indicating that the map for 91 octane should be used is output to the map selection means 61a, and the map for 91 octane is selected for the basic ignition advance angle, flap control duty ratio, and bypass valve control duty ratio. control.

If knocking does not occur in S76, the ignition advance changing means 64 changes the octane advance so that the ignition advance is 8 degrees further than the initially set basic ignition advance angle for the 95 octane rating, which is an even more severe condition for knocking. It is output to the determining means 65 (S77).

Then, in S79, it is detected whether or not knocking occurs.
If knocking occurs, it is determined that the currently used fuel has a lower octane number of 93. The determination results are outputted to the ignition advance control means 60, the flap control duty ratio setting means 46, and the bypass valve control duty ratio setting means 52, respectively, and the control is performed using the corresponding map for 93 octane (
S80).

If knocking does not occur in step 379, the ignition advance angle is further advanced by 4 degrees and advanced by 12 degrees from the initial setting reference ignition advance angle (381), and it is detected in step S82 whether or not knocking occurs. do. If knocking occurs, if you are currently using 95 octane fuel with a lower octane number, you should definitely use the 95 octane map in the control gear M and the ignition advance control means 6o. Outputs the message.

If knocking does not occur in S82, it is determined that fuel with an octane rating of 98, which is one rank higher than fuel with an octane rating of 95, is used.

In this way, the exhaust control means M and the ignition advance control means 60 are controlled according to the octane number of the currently used fuel detected by the octane number detection means 57, so that the optimum supercharging that matches the octane number of the currently used fuel is achieved. Pressure control and ignition advance control are possible.

In this way, for example, the boost pressure control target value can be set to 350+n in response to 91 octane fuel (regular gasoline).
If set to m11g, use the same engine to
If the engine is operated using fuel with an octane number (high octane), the supercharging pressure can be increased to 465mmt1g in accordance with the octane number, so the engine output can be significantly increased by about 16χ.

After the octane number detection means 57 determines the octane number of the currently used fuel, the determination result is held for a predetermined period of time. The predetermined period of time may be a set period of time, or may be until the key is turned off or until gasoline is refilled.

In consideration of the case where the octane number of the fuel used was determined in error as described above, the output of the octane number determining means 65 is corrected by the correcting means 69.

As shown in FIG. 7, once the ignition advance control and exhaust gas control are performed in accordance with the detected octane number and the operation is continued, the non-noking sensor 31 reaches 39°.
5 when it is detected that knocking has occurred in 1.
A command signal is issued to the ignition advance angle control means 60 to delay the advance value by 2 degrees (S92).

Then, as a result of count amplification in 393, if the ignition advance retardation amount RET exceeds 4 degrees in 394, the control map of each duty ratio setting means 46.52 is selected to have an octane number one rank lower. Command (S95.
596). Then, at 397, the flag is set to the ignition advance delay amount R.
At ET and O, the octane number detection action shown in FIG. 5 is performed again. If the occurrence of non-king is detected in S91 even in this manner, the above-mentioned operation is repeated to lower the octane number one by one.

The octane number of the octane number detection means 57 should be at least 2 levels (regular gasoline and high-octane gasoline), but by using the intermediate level judgment and the corresponding control map, it can be used when using intermediate octane number gasoline, or Even when two types of gasoline with high and low octane numbers are mixed and used, optimal supercharging pressure control can be performed for each.

Note that the octane number detection means 57 is not limited to this embodiment, and may be such that the octane number of the fuel used is manually detected at the time of fuel supply, or a method of electrically or chemically detecting the octane number of the fuel itself may be used. Needless to say, you can adopt it.

FIG. 8 is a block diagram showing the general functions of the octane number detection means 57 in this embodiment.

<Effects of the Invention> As described above, according to the present invention, the exhaust control device that controls the flow of exhaust gas supplied to the exhaust turbine of the exhaust turbocharger is controlled according to the operating state and the octane number of the fuel used, Since the target boost pressure is obtained according to the octane number, optimal boost pressure control can be performed according to the octane number of the fuel, and when low octane fuel is used, the boost control pressure is lowered to prevent knocking or engine knocking. It is possible to prevent burnout (=J), and when using high octane fuel, it is possible to maximize the boost control pressure and obtain high output.Also, changing the boost pressure depending on the octane number of the fuel reduces the variation in octane number. It is possible to increase the compression ratio of the engine without considering the above, and it is possible to improve fuel efficiency and engine output.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 3 is a block diagram showing the operation of the control unit 30 in the above, and Fig. 4 is an octane rating diagram in the same. A block diagram showing the detection means, FIG. 5 is a flowchart showing the operation of the octane number detection means, FIG. 6 is a graph showing the octane number determination zone Z, and FIG. 7 explains the action of the correction means 69 shown in FIG. 4. FIG. 8 is a block diagram showing the basic configuration of an embodiment of the octane number detection means shown in FIG. 4. ■... Internal combustion engine 2... Intake passage 4... Exhaust turbocharger 5... Compressor 8... Rotation sensor 11... Exhaust passage 12... Exhaust turbine 13... Bypass passage 14. ...Bypass valve 16
．． 23...i ljf Valve 21...Flap 30
... Control unit 31 ... Non-king sensor 46 ... Flap control duty ratio setting means
46a... Map selection means 48a1 to 48an...
- Map 52...Bypass valve control duty ratio setting means 52a...Map selection means 53a1 to 53a
n...Ma/p M...Exhaust control means 60...Ignition advance angle control means 61...Basic ignition advance angle setting means 6
1a... Ma knob selection means 62a1 to 62an...
・Basic ignition advance angle map 64...Ignition advance angle changing means
65...Octane number determination means 67...Judgment start control means 69...Amendment means patent applicant Fujio Sasashima, agent for Nissan Motor Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] (1) An engine operating state detection means, a means for detecting the octane number of the currently used fuel, an exhaust control device for controlling the flow of exhaust gas supplied to the exhaust turbine of the exhaust turbocharger, and the exhaust gas A supercharging pressure for an exhaust turbocharger, comprising: control means for controlling a control device according to an engine operating state and an octane number of the fuel used given from the octane number detection means to obtain a target supercharging pressure. Control device. ′
(2) A patent characterized in that the exhaust control device is at least one of a valve device that controls the flow rate of exhaust gas supplied to an exhaust turbine of an exhaust turbocharger, and a bypass valve provided in a device that bypasses the exhaust turbine. A supercharging pressure control device for an exhaust turbocharger according to claim 1. (3) The octane number detection means includes an ignition advance control means that controls the basic ignition advance angle according to the octane number of the fuel according to the engine operating state, and an ignition advance angle control means that controls the basic ignition advance angle according to the octane number of the fuel, and a basic ignition advance changing means for changing the basic ignition advance in accordance with a specific octane number of fuel; means for detecting a knocking level of the engine; octane number determination means for determining the octane number of the currently used fuel based on the present invention.
The supercharging pressure control device for an exhaust turbocharger according to item 1 or 2. (4) The octane number detection means detects the knocking level based on the basic ignition advance controlled by the ignition advance control means corresponding to the octane number of the currently used fuel determined by the octane number determination means and the detected knocking level. The supercharging pressure control device for an exhaust turbocharger according to claim 1, further comprising a correction means for correcting the determined octane number. (5) The exhaust turbocharger according to any one of claims 1 to 4, wherein the octane number detection means is a means for outputting a detection result to the ignition advance control means. Boost pressure control device.