JPH0213135B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention provides supercharging pressure control for an exhaust turbocharger that controls the rotation of the exhaust turbine and controls the supercharging pressure by changing the flow velocity of exhaust gas that is guided to the exhaust turbine of the exhaust turbocharger. Regarding equipment.

<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 improving the output. However, when the boost pressure becomes excessive, excessive stress acts on the internal combustion engine and its intake and exhaust system, creating the risk of damage or breakage. Further, when the internal combustion engine with exhaust turbocharging is operated in a low load range, there is a disadvantage that the displacement is small, so the supercharging pressure is small and the output is likely to be insufficient. Therefore, various means have been conventionally taken to prevent such an excessive rise in supercharging pressure and insufficient supercharging pressure.

One of the preventive measures is, for example, U.S. Patent No.
There is an exhaust flow rate control device found in US Pat. No. 2,944,786. This system is equipped with a flap at the exhaust inlet of the exhaust turbocharger, and by adjusting the degree of opening of the flap, the flow velocity at the exhaust inlet toward the exhaust turbine is controlled, and the exhaust flow velocity is increased in the engine low load rotation region. , the rotational speed of the compressor is increased to increase the boost pressure, and in the high load region of the engine, the opening degree of the flap is increased to reduce the exhaust flow velocity and prevent the exhaust turbine from over-speeding.
This also prevents the compressor from increasing the supercharging pressure.

However, with such conventional boost pressure control devices, if the flap position control means that controls the flap position breaks down or seizes up and the flap is stuck at a small opening, When the engine rotates at high speed, the flap opening cannot be increased as required, and the exhaust pressure on the upstream side of the flap becomes abnormally high, causing the exhaust turbocharger to overspeed, resulting in damage to its rotating shaft or damage to the flap or engine. or the back pressure of the engine may increase, causing pumping loss.
There was a risk that this would lead to a decrease in output, and deterioration in fuel efficiency and exhaust properties.

As a conventional method to prevent such inconveniences, the flow velocity at the exhaust inlet toward the exhaust turbine is controlled by an area control member at the exhaust inlet of the exhaust turbine, and the exhaust flow velocity is increased in the engine low load rotation region to raise the supercharging pressure and reduce the engine height. In the load rotation range, the exhaust flow velocity is reduced to prevent excessive rise in boost pressure, while if the exhaust pressure upstream of the exhaust turbine becomes excessive, the exhaust bypass valve is opened and the exhaust is bypassed downstream of the exhaust turbine. There is a method disclosed in Japanese Utility Model Application Publication No. 56-113125.

According to this, regardless of whether the area control member at the inlet of the exhaust turbine functions normally or is in an abnormal state in which it is stuck in a small area, if the pressure upstream of the exhaust turbine exceeds a predetermined value, it will automatically Since the bypass valve is opened, there is no distinction between exhaust bypass valve opening control during normal and abnormal conditions. However, if the above-mentioned area control member is normal, it is effective to precisely control the area of the exhaust bypass valve according to the engine operating condition, but in the case of an abnormality such as the area control member sticking, Accurate valve opening control of the exhaust bypass valve has the disadvantage of applying excessive pressure to the area control member and damaging it. It is necessary to predict a situation in which the exhaust pressure on the upstream side of the exhaust turbine becomes excessive and to prevent this from occurring. This point has not been addressed in conventional systems.

<Object of the Invention> In view of the above-mentioned disadvantages of the conventional device, the present invention controls the position of the flap that normally controls the exhaust flow velocity supplied to the exhaust turbine of the exhaust turbocharger according to the engine operating state, and also bypasses the exhaust turbine. The actuator of the bypass valve is actuated according to the engine operating state to control the opening of the bypass valve, while when the flap is abnormal, the normal operation of the bypass control means is canceled and a different control is adopted instead. The purpose of this invention is to stepwise increase the bypass valve opening to a predetermined value regardless of the engine operating state.

<Structure of the Invention> To achieve this, the present invention provides a supercharging pressure control device for an exhaust turbocharger, which is provided with a flap for controlling the exhaust flow velocity that supplies an exhaust turbine, and a means for controlling the flap position, as shown in FIG. In,
a bypass valve provided in a passage that bypasses the exhaust turbine; an actuator for driving the bypass valve; bypass control means for controlling the opening of the bypass valve by operating the actuator in accordance with engine operating conditions; and a position of the flap. or a flap abnormality detecting means for detecting a related element thereof, and when the abnormality detecting means detects an abnormality of the flap, the actuator is actuated with priority over the operation of the bypass valve control means, regardless of the engine operating state. First, bypass correction means for increasing the bypass valve opening degree to a predetermined value stepwise is provided.

<Function> Under normal conditions, the opening of the bypass valve is controlled according to the engine operating state, and the exhaust pressure on the upstream side of the exhaust turbine is accurately controlled to an appropriate value, but once the flap is in an abnormal state such as sticking. Then,
Since accurate opening control of the bypass valve is no longer necessary, the bypass correction means acts and immediately switches to bypass valve opening control in abnormal conditions, that is, control that increases the opening stepwise to a predetermined value. Therefore, when a flap abnormality occurs, the bypass valve quickly opens to a sufficient degree, lowering the exhaust pressure upstream of the flap to prevent damage to the flap, etc., and preventing a drop in engine output, improving fuel efficiency and exhaust properties. be able to.

<Example> Examples 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 1 is supplied to the combustion chamber through an intake passage 2. In the embodiment shown in FIG. During this period, the amount of intake air Qa is measured by the air flow meter 3, the intake air is fed under pressure (supercharged) by the compressor 5 of the exhaust turbocharger 4, and the amount is regulated by the intake throttle valve 6. and fuel injection valve 7
The mixture is mixed with fuel injected from the engine and introduced into the combustion chamber, where it is combusted to produce output. The engine rotational 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 is transferred to the exhaust turbocharger 4.
The exhaust gas turbine 12 is driven to rotate, and the exhaust gas is discharged to the outside. The exhaust turbine 12 is connected to the compressor 5 by a shaft 4a.
The rotation of the compressor 5 simultaneously drives the compressor 5 to rotate.

Here, the exhaust passage 11 has an exhaust turbine 1
A bypass passage 13 is provided to guide exhaust gas by bypassing 2, and a bypass valve 14 for opening and closing the bypass passage 13 is interposed.

The bypass valve 14 is rotated by an actuator consisting of a diaphragm device 15, and the solenoid valve 16
The rotation thereof is controlled by bypass valve control means whose main elements include the pressure passage 17 and the like. That is, a bypass valve 14 is connected to a diaphragm 15a of the diaphragm device 15 via a link 15b, and supercharging pressure downstream of the compressor 5 is introduced via a pressure passage 17 to a pressure operating chamber 15c provided on one side of the diaphragm 15a. It will be destroyed. A three-way switching type solenoid valve 16 is installed in the pressure passage 17, and is configured to release the supercharging pressure in the pressure passage 17 to the atmosphere by opening the atmospheric port 16a.
The opening/closing time ratio of the atmospheric port 16a is controlled to increase/decrease the pressure in the pressure working chamber 15c, and the opening degree of the bypass valve 14 is controlled via the diaphragm 15a.

A flap 21 for controlling the exhaust flow rate is provided in the exhaust passage 11 between the bypass valve 14 and the exhaust turbine 12, preferably at the scroll inlet of the exhaust turbine 12.
will be established. The upstream end of the flap 21 is rotatably supported by a casing at the scroll inlet of the exhaust turbine 12, and its downstream end swings to increase or decrease the inlet opening area of the exhaust turbine 12. It is structured as follows. As the opening area increases (position b shown by the solid line in the figure), the exhaust flow rate decreases, and as the opening degree decreases (position a shown as the dotted line in the figure), the exhaust flow rate increases.

The position of the flap 21 is controlled by a flap position control means whose main components are a diaphragm device 22 and a solenoid valve 23. That is, a flap 21 is connected to a diaphragm 24 of a diaphragm device 22 via a link 25, and a pressure passage 2 is connected to a pressure operating chamber 26 provided on one side of the diaphragm 24.
The supercharging pressure between the compressor 5 and the intake throttle valve 6 is conducted via the compressor 7. The pressure passage 27 has a three-way switching type solenoid valve 23 having an atmospheric port 23a.
is interposed, and increases or decreases the supercharging pressure introduced into the pressure working chamber 26 by controlling the time ratio of opening and closing the atmospheric port 23a.

The pressure in the exhaust passage 11 on the upstream side of the flap 21 (exhaust pressure Pe) is detected by an exhaust pressure sensor 31, which is exhaust pressure detection means. In the figure, 6a is a throttle sensor that detects the opening degree θ of the intake throttle valve 6, 28 is a warning lamp, and 29 is an ignition switch.

These fuel injection valves 7 and electromagnetic valves 16 and 23 receive various detection signals output from the pressure sensor 9, throttle sensor 6a, air flow meter 3, rotation sensor 8, and exhaust pressure sensor 31, which act as engine operating state detection means. The command is controlled to the optimum value calculated by the control unit 30 based on.

The flap 21 is operated by a stroke switch 32 that detects a position near the maximum displacement of the diaphragm 24 in the diaphragm device 22.
1 is detected to be at position a near the minimum opening degree.

The related operations of these components will be explained with reference to the block diagram shown in FIG. 3 and the flowchart shown in FIG. 4.

Detection signals from the air flow meter 3 and rotation sensor 8, which function as engine operating state detection means, are input to the intake air amount detection means 41 and rotation speed detection means 42, where the intake air amount Qa and engine rotation speed N are read. (S61), the injection pulse is input to the injection pulse calculation means 43.

In the injection pulse calculation means 43, TP=K・Qa/N
A basic injection pulse width TP corresponding to the amount of fuel injected per engine rotation is calculated using the following relational expression (S62), and its output signal is used by the injection valve control means 44, the flap control duty ratio setting means 45, and the bypass valve control duty ratio. It is input to the setting means 48.

The injection valve control means 44 receives inputs of other engine operating state signals such as throttle opening θ, supercharging pressure PS, exhaust pressure Pe, etc., and makes various corrections to the basic fuel injection pulse width TP, thereby controlling the injection. A valve driving pulse is output to the injection valve 7. Incidentally, the injection pulse calculation means 43 and the injection valve control means 44 constitute a fuel injection control means h.

The flap control duty ratio setting means 45 reads out the control duty ratio from the memory 46 having a map as shown in FIG. 5, which is allocated by the basic fuel injection pulse width TP and the engine rotational speed N (S63), and sets the value thereof. is output to the control means 47 of the flap solenoid valve 23. The solenoid valve control means 47 outputs a drive current having a set duty ratio (command signal corresponding to the control target position of the flap) to drive the flap solenoid valve 23.

Here, for example, when the duty ratio is 0%, the solenoid valve 23 opens the atmospheric port 23a and releases the pressure in the pressure passage 27 to the atmosphere.
By reducing the pressure of
The inlet opening area of the exhaust turbine 12 is made smaller, thereby increasing the exhaust flow velocity and increasing the rotation speed of the exhaust turbine 12. Furthermore, when the duty ratio is 100%, the solenoid valve 23 closes the atmospheric port 23a, increases the pressure in the pressure working chamber 26, and displaces the flap 21 via the diaphragm 24 to the maximum valve opening position indicated by the solid line position b, so that the exhaust turbine 12 The inlet opening area is increased to reduce the exhaust flow velocity and decelerate the rotation of the exhaust turbine 12. Therefore, by controlling the duty ratio of the solenoid valve 23, a desired stroke amount of the flap 21 can be obtained, and the exhaust gas flow rate and thus the boost pressure supplied to the exhaust turbine 12 can be freely controlled according to the engine operating state. can do.

In addition, the flap control duty ratio setting means 4
5, memory 46, solenoid valve control means 47, solenoid valve 2
3 and the like will be referred to as the flap position control means i.

The bypass valve control duty ratio setting means 48 includes:
The basic fuel injection pulse width TP and engine rotation speed N
For example, the control duty ratio is read from the memory 49 having a map as shown in FIG. The time rate of opening and closing of the port 16a is controlled. As a result, the opening degree of the bypass valve 14 is controlled to increase or decrease in accordance with the engine operating state, that is, the basic fuel injection pulse width T _P and the engine operating speed N, in the same manner as in the case of flap control. As the opening degree of the bypass valve 14 increases depending on the engine operating state, the bypass passage 13 is opened without rotating the exhaust turbine 12.
The exhaust flow toward the engine increases, the rotational energy of the exhaust turbine 12 is reduced, the compressor 5 is prevented from over-rotating, and the supercharging pressure can be prevented from increasing too much. Furthermore, here,
Bypass valve control duty ratio setting means 48, memory 49, electromagnetic valve control means 50, pressure passage 17, electromagnetic valve 16, etc. will be referred to as bypass valve control means j.

When such flap position control and bypass valve control are performed in a steady state, the flag is set to 0 (STICK = 0) in S69 and a closing routine is configured to adjust the exhaust flow velocity and exhaust pressure. The control is performed with high accuracy according to the engine operating state, and the boost pressure is controlled to the optimum value, but the opening degree of the flap 21 is at a position larger than a predetermined value (for example, flap control duty ratio of 60% or more). Even though the control target value Ft is output, the stroke switch 32
is on, that is, detects a position a near the minimum flap opening, it is predicted that the control is not being performed smoothly and there is a possibility that the flap 21 is stuck, and the above-mentioned normal bypass valve opening is Cancel the control and switch to abnormality control instead.
Bypass valve 14 is increased to a predetermined value.

That is, the comparison means 52 inputs the control target position Ft (flap control target duty ratio) of the flap position set by the flap control duty ratio setting means 45, and also controls whether the stroke switch 32 is turned on or off.
An off signal, that is, a signal Fa indicating whether the stroke position of the flap 21 is at the minimum opening position a is input.
And in S66, the flap control duty ratio is
It is determined that a large opening of 60% or more is output as the control target position, and then in S67 it is determined whether the stroke switch 32 is on, and the control target position Ft with a large flap opening is detected. If you find that the actual flap opening Fa is near the position a, that is, the minimum opening position, then it is determined that the flap 21 may have malfunctioned or seized due to some reason. Flag 1 with S68
(STICK=1), and the solenoid valve control means 50
Output that signal to. Therefore, the stroke switch 32 and the comparison means 52 constitute a flap abnormality detection means K.

The solenoid valve control means 50 that received this signal,
At S70, a correction signal is output to the solenoid valve 16 to set the flap control duty ratio to 100%, and the bypass valve 14 is fully opened. Therefore, the solenoid valve control means 50
This also serves as the bypass correction means in the present invention.

As a result, although the control objective is to open the flap 21 to slow down the exhaust flow velocity and reduce the rotational energy of the exhaust turbine 12 to reduce the boost pressure, or to prevent the overload pressure from rising excessively, , it can be seen that the actual opening degree of the flap 21 has become smaller, making the above control impossible. Since such a situation is extremely dangerous, the normal precision control of the bypass valve depending on the engine operating state is canceled and instead, the opening degree of the bypass valve 14 is increased stepwise to a predetermined value to prevent exhaust gas. The exhaust gas flows through the bypass passage 13 to reduce the rotational energy of the exhaust turbine 12 and prevent the supercharging pressure from rising excessively.

This state is detected by the comparison means 52 and the alarm control means 5.
4 (S71), the alarm lamp 28 is activated to warn that there is an abnormality in the flap 21 or its control means.

Further, in the above embodiment, the flap abnormality detection means K detects whether or not the flap is at the minimum opening position, that is, the predetermined stroke position.
A stroke sensor that detects the stroke amount of 1 may be provided. In this case, as shown in FIGS. 7 and 8, the detection signal of the stroke sensor 32A is input to the stroke detection means 51, and in S81 the actual stroke amount SV of the flap is read and output to the comparison means 52.

In the comparison stage 52, the basic fuel injection pulse width TP
The control target position (stroke amount) Sm of the flap is read from the map as shown in FIG.
<Ft-c (where c is a constant) is compared and determined (S83). As a result, if it is found that the actual measured value SV is outside the allowable range than the control target position Sm, the process proceeds to S68 shown in Fig. 4 to increase the opening degree of the bypass valve, and if it is within the allowable range, the process proceeds to S69 and the opening degree of the bypass valve is increased. It is determined that the flap does not have any abnormality such as seizure. Other configurations and operations are the same as those in FIGS. 3 and 4.

In this embodiment, the flap control target position
Although Sm is read from TP and N using a map in the memory 53, this may also be the flap control target position signal Ft output from the flap control duty ratio setting means 45. From this meaning,
Injection pulse calculation means 43, rotational speed detection means 42, comparison means 52 and memory 53 in this embodiment
constitutes a flap abnormality detection means.

According to the above two embodiments, since the comparison signal inputted to the comparison means 52 is a signal representing the position (stroke) of the flap, it was possible to directly compare them as the same state quantity. However, in order to detect a flap abnormality, it is not necessary to directly detect the flap position in this way.
This can also be determined from the upstream exhaust pressure Pe or supercharging pressure Ps.

Therefore, an example in which exhaust pressure is detected instead of detecting the flap position will be explained with reference to FIGS. 9 and 10.

As for the exhaust pressure on the upstream side of the exhaust turbine 12 detected by the exhaust sensor 31, the exhaust pressure detection means 91 reads out an exhaust pressure signal Pe (S101), which is compared to the comparison means 92.
At the same time, the intake air amount Qa signal output from the intake air amount detection means 41 is inputted to the comparison means 92. The comparing means 92 stores the intake air amount mapped in advance in the memory 93 as shown in FIG.
Allowable exhaust pressure for Qa (that is, the allowable exhaust pressure under the engine operating conditions at that time, and is a pressure that can change according to changes in the engine operating conditions)Pek
is read out (S107), and the permissible exhaust pressure value Pek is compared with the detected exhaust pressure Pe (S103). When the detected exhaust pressure Pe is higher than the allowable exhaust pressure Pek (Pek<Pe...shaded area in FIG. 12), it is determined that there is an abnormality and the opening degree of the bypass valve 14 is increased (S70). Therefore, here, the intake air amount detection means 41, the exhaust pressure sensor 31, the exhaust pressure detection means 91,
Comparison means 92 and memory 93 constitute flap abnormality detection means K.

To explain using the map shown in Fig. 12, the exhaust pressure Pe increases as the intake air amount Qa increases,
It also increases as the opening degree of the flap 21 decreases.
In the figure, the exhaust pressure curve m when the flap is closed is higher than the exhaust pressure curve n when the flap is open, and if this exhaust pressure increases beyond a predetermined value, the output will decrease due to engine pumping loss, etc., and the boost pressure will decrease. Since engine damage due to excessive rise is likely to occur, this is prevented by fully opening the flap 21 on the large intake air amount Qa side from the l line to lower the exhaust flow velocity and reduce the energy for driving the turbine rotation. Of course, in the zone where abnormal exhaust pressure occurs even when the flap is fully opened, the bypass valve opening degree is increased by the normal operation of the bypass valve side control means to obtain the valve opening degree of the bypass valve according to the engine operating state. The pressure is reduced, but in the region where the exhaust pressure increases abnormally when the flap is closed, it is determined that this is the result of flap failure or seizure, and the bypass is currently controlled to match the flap opening. The valve is switched to abnormality control and the opening degree is increased in steps to reduce exhaust pressure.

In this way, flap abnormalities can be detected not only from the flap position itself but also by detecting abnormalities in the engine operating status, etc.
It is not limited to the disclosed embodiments.

<Effects of the Invention> As described above, the present invention uses both a flap that increases and decreases the exhaust turbine inlet flow velocity and a bypass valve installed in a passage that bypasses the exhaust turbine to adjust the exhaust flow velocity and exhaust pressure during normal operation. At the same time, we detected an abnormality in the flap, canceled the normal control of the bypass valve opening, and instead switched to abnormal control to increase the bypass valve opening in a stepwise manner. It is possible to reliably prevent an excessive rise in exhaust pressure when a flap is stuck in a small opening state in an engine. This prevents an excessive increase in supercharging pressure due to overspeeding of the exhaust turbocharger, thereby protecting the exhaust turbocharger, engine, etc., and also prevents a decrease in output and improving fuel efficiency and exhaust properties. .

[Brief explanation of drawings]

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 same, and FIG. 30, FIG. 5 is a map showing the control duty ratio corresponding to TP and N stored in the memory 46 in FIG. 3, and FIG. 6 is a map showing the control duty ratio corresponding to TP and N stored in the memory 49. A map showing the duty ratio, FIG. 7 is a block diagram showing a modification of the control unit 30 shown in FIG. 3, FIG. 8 is a flowchart of the same, and FIG. N
FIG. 10 is a map showing the flap control stroke amount Sm corresponding to the control unit 30 shown in FIG.
Figure 1 is the same flowchart as above, Figure 12 is the 10th diagram.
This is a map showing the relationship between Pe, Qa, and Pek stored in the memory 93 in the figure. 1... Internal combustion engine, 2... Intake passage, 3... Air flow meter, 4... Exhaust turbo charger, 5
...Compressor, 6a...Throttle sensor,
8... Rotation sensor, 9... Pressure sensor, 11...
Exhaust passage, 12...Exhaust turbine, 13...Bypass passage, 14...Bypass valve, 15, 22...
Diaphragm device (actuator), 16,2
3... Solenoid valve, 17... Pressure passage, 21... Flap, 30... Control unit, 31...
Exhaust pressure sensor, 32... Stroke switch, 32
A...Stroke sensor, 50...Solenoid valve control means, i...Flap position control means, j...Bypass valve control means, K...Flap abnormality detection means.

Claims (1)

[Scope of Claims] 1. An engine operating state detection means, a flap that controls the flow rate of exhaust gas supplied from the exhaust turbocharger to the exhaust turbine, a flap position control means that controls the position of the flap according to the engine operating state, and an exhaust turbine. a bypass valve provided in a passage that bypasses the bypass; an actuator for driving the bypass; bypass valve control means for controlling the opening of the bypass valve by operating the actuator in accordance with engine operating conditions; and abnormality detection means for the flap. When the abnormality detection means detects an abnormality in the flap, it operates the actuator in priority to the operation of the bypass valve control means, and steps the bypass valve opening degree to a predetermined value regardless of the engine operating state. 1. A supercharging pressure control device for an exhaust turbocharger, comprising: bypass correction means for increasing the boost pressure of an exhaust turbocharger. 2. The flap abnormality detection means includes means for detecting the position of the flap, and comparison means for comparing the detection value of the means with the flap control target position by the flap position control means and determining that the difference between the two is outside the allowable range. The supercharging pressure control device for an exhaust turbocharger according to claim 1, characterized in that it is configured to include the following. 3. The supercharging pressure control device for an exhaust turbocharger according to claim 1, wherein the flap abnormality detection means is a means for detecting an abnormality in exhaust pressure upstream of the exhaust turbine.