JP4052040B2 - Supercharger control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a supercharger control device for an internal combustion engine, and more particularly to prevention of abnormal noise generated by a sudden change in supercharging pressure downstream of a compressor of a supercharger when an accelerator is off.
[0002]
[Prior art]
In a diesel engine with a variable capacity supercharger, when decelerating from a state where the supercharging pressure is high, reliability such as abnormal noise generated by abrupt changes in the supercharging pressure downstream of the turbocharger compressor and supercharger Japanese Patent Laid-Open No. 2001-132508 discloses a method for preventing the deterioration of the property by controlling the fuel injection amount.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, the basic fuel injection amount is corrected by increasing the detected value of the accelerator opening when the accelerator is turned off (rapidly closed), so the fuel cut at the time of deceleration is not performed, and the fuel consumption deteriorates. There was a problem.
[0004]
Therefore, the present invention has an object to prevent the generation of the abnormal noise without deteriorating the fuel consumption.
[0005]
[Means for Solving the Problems]
In the present invention, a variable capacity turbocharger comprising a vane opening adjustment mechanism for changing the vane opening, and means for detecting operating conditions, the degree of opening of the vane opening adjustment mechanism based on the operating condition, the engine In a supercharger control apparatus for an internal combustion engine, comprising: a control means configured to set such that the higher the rotation speed is, the larger the rotation speed is, and the smaller the rotation speed is. Detects a decrease in the accelerator opening regardless of the setting in at least a predetermined range of the operating state in which an abnormal noise is generated due to a pressure fluctuation in the intake passage downstream of the variable displacement supercharger when the accelerator opening decreases. Sometimes the vane opening is controlled to be larger than before the accelerator opening is reduced.
[0006]
[Action / Effect]
According to the present invention, when the accelerator opening is decreased, the vane opening is made larger than before the accelerator opening is decreased, so that the increase in the turbine speed can be suppressed. It is possible to prevent abnormal noise caused by various changes.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
FIG. 1 shows a reference example for comparison with the present invention.
[0009]
Reference numeral 10 denotes a variable displacement supercharger, which includes a turbine housing 1 that houses a turbine wheel 2 and a variable vane 3, and a compressor housing 7 that houses an impeller 8.
[0010]
The turbine wheel 2 converts exhaust energy of exhaust gas discharged from an exhaust port (not shown) and introduced from the turbine housing inlet 11 into the turbine housing 1 into rotational energy, and is connected to a turbine shaft 9 coaxially. Rotate 8 By this rotation, the impeller 8 passes through an air cleaner (not shown), compresses the intake air introduced from the compressor inlet 13, and sends the compressed air from the compressor outlet 14 to an intake passage (not shown) connected to the intake port.
[0011]
The variable vane 3 is disposed so as to surround the turbine wheel 2 and is driven by the actuator 4 to change the vane opening degree. The movement of the variable vane 3 is controlled by the engine control unit 6 to increase the flow rate of the exhaust gas introduced into the turbine wheel 2 in the low rotation speed range so that a predetermined supercharging pressure can be obtained from the low rotation speed range. In order to close the variable vane 3, the variable vane 3 is controlled to open in order to introduce the exhaust gas into the turbine wheel 2 without resistance in the high rotational speed range.
[0012]
Further, as will be described later, the engine control unit 6 opens the variable vane 3 when the accelerator is off (rapidly closed) to prevent the generation of abnormal noise.
[0013]
The engine control unit 6 performs the above control based on signals input from the engine speed sensor 21, the accelerator opening sensor 22, and the fuel injection amount sensor 23.
[0014]
The actuator 4 includes a diaphragm actuator 4a that drives the variable vane 3 in response to the control pressure, and a pressure control valve 4b that adjusts the control pressure to the diaphragm actuator 4a. The actual opening of the variable vane 3 is the target nozzle opening. A duty control signal is generated so that the duty control signal is output to the pressure control valve 4b.
[0015]
FIG. 2 shows a flowchart of the control operation when the accelerator is off executed by the engine control unit 6, and FIG. 3 shows a timing chart showing changes in various state quantities at the time of deceleration.
[0016]
In step S11, the engine speed and the fuel injection amount are read, and in step S12, it is determined whether or not the accelerator opening is decreased (off). When the accelerator off is detected in step S12, the process proceeds to step S13 and the opening of the variable vane 3 is controlled to be larger by a certain amount than before the accelerator is turned off.
[0017]
If accelerator off is not detected in step S12, a map for controlling the opening of the variable vane 3 as shown in FIG. 5 is read in step S14, and the target vane opening is determined from the engine speed, fuel injection amount, and accelerator opening. Decide and control.
[0018]
When the vane opening is determined in steps S13 and S14, the vane opening is duty-converted in step S15.
[0019]
Conventionally, when the accelerator is turned off from a state where the supercharging pressure is high such as during acceleration, the variable vane 3 is closed as shown in FIG. 3A in order to efficiently increase the supercharging with the exhaust energy reduced by the accelerator off. Was controlled.
[0020]
As a result, the rotational speed of the impeller 8 increases, and a sudden pressure fluctuation occurs downstream of the impeller 8, and abnormal noise is generated by the intake air blown back toward the impeller 8 at this time.
[0021]
However, in this reference example , since the variable vane 3 is opened as shown in FIG. 3B when the accelerator is off, the above-described pressure fluctuation can be prevented.
[0022]
As described above, in this embodiment, when the accelerator is turned off, the opening of the variable vane 3 is increased to suppress the increase in the rotational speed of the impeller 8 and prevent a sudden pressure change downstream of the impeller 8. Can be prevented.
[0023]
In addition, since it is not necessary to make the detected value of the accelerator opening, the fuel cut can be started immediately, and the deterioration of the fuel consumption can be prevented.
[0024]
An embodiment of the present invention will be described with reference to FIGS.
[0025]
In this embodiment, after reading the rotational speed and the fuel injection amount in step S21, it is determined in step S22 whether the engine is within a predetermined rotational speed range (for example, 1700 to 2300 rpm). This predetermined rotation speed range is a range in which abnormal noise occurs, and conversely, no abnormal noise is generated outside this range. If it is within the predetermined rotation speed range, the process proceeds to step S23 and the same control as in the reference example is performed.
[0026]
If the engine is not at the predetermined rotational speed, the process proceeds to step S25, and the vane opening degree is controlled according to the variable vane 3 control map.
[0027]
This is because, when the engine speed is low, such as extremely low speed operation in a traffic jam, even if the variable vane 3 is closed when the accelerator is off, the pressure fluctuation downstream of the impeller 8 does not generate abnormal noise. This is because there is no problem with the control using the map.
[0028]
If accelerator-off is detected in step S23, the opening of the variable vane 3 is opened in step S24. At this time, the variable vane 3 is fully opened without reading the variable vane 3 control map.
[0029]
This saves time for calculating the opening of the variable vane 3 from the fuel injection amount and the engine speed, so that the variable vane 3 is immediately fully opened as shown in FIG. It is effective for prevention.
[0030]
As described above, in the present embodiment, the supercharging pressure is high as in acceleration, and it is possible to detect a situation in which abnormal noise occurs when the accelerator is turned off, and to perform control to prevent the occurrence of abnormal noise. .
[0031]
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a variable capacity supercharger.
FIG. 2 is a flowchart of a reference example .
FIG. 3 is a chart for explaining a change in the opening degree of the variable vane when the accelerator opening degree is decreased.
FIG. 4 is a flowchart of an embodiment of the present invention .
FIG. 5 is a characteristic diagram of variable vane control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Turbine housing 2 Turbine wheel 3 Variable vane 4 Actuator 4a Diaphragm actuator 4b Pressure control valve 6 Engine control unit 7 Compressor housing 8 Impeller 9 Turbine shaft 10 Variable capacity supercharger 21 Engine speed signal 22 Accelerator opening signal 23 Fuel injection Amount signal S11, 21 Reading of the rotation speed signal and the fuel injection amount signal.
S12, 23 Read accelerator opening signal.
S13, 24 Control to open variable vanes.
S14, 25 Calculates the vane opening according to the vane opening control map.
S15, 26 Vane opening is converted to duty.
A Change in variable vane opening of the prior art.
B Change in variable vane opening in Reference Example .
C Change in the variable vane opening degree of the present embodiment .

Claims (4)

A variable displacement supercharger having a vane opening variable mechanism for changing the vane opening;
Means for detecting the operating state;
Control that sets the opening of the variable vane opening degree mechanism according to the operating state so that the opening becomes larger as the engine speed increases and decreases as the engine speed increases, and decreases as the engine load increases and decreases as the engine load increases. An internal combustion engine supercharger control device comprising:
The control means reduces the accelerator opening regardless of the setting in at least a predetermined range of the operating state in which abnormal noise is generated due to pressure fluctuation in the intake passage downstream of the variable displacement supercharger when the accelerator opening decreases. A supercharger control device for an internal combustion engine, wherein when the engine is detected, the vane opening is controlled to be larger than before the accelerator opening is reduced. The predetermined range of the operating state in which abnormal noise is generated due to pressure fluctuation in the intake passage downstream of the variable displacement supercharger when the accelerator opening is decreased is a middle rotation range of the engine speed. Item 2. The supercharger control device for an internal combustion engine according to Item 1. The control means opens the vane when it detects a decrease in the accelerator opening in a predetermined range of an operating state in which abnormal noise is generated due to pressure fluctuations in the intake passage downstream of the variable displacement supercharger when the accelerator opening decreases. The supercharger control device for an internal combustion engine according to claim 1 or 2, wherein the degree is fully opened. The control means reads the vane opening degree control map based on the operating state and sets the vane opening degree. On the other hand, when the accelerator opening degree decreases , the control means varies depending on the pressure fluctuation in the intake passage downstream of the variable displacement turbocharger. When a decrease in the accelerator opening is detected within a predetermined range of operating conditions where noise is generated , reading of the vane opening control map is prohibited, and the vane opening is made larger than before the accelerator opening is decreased. The supercharger control device for an internal combustion engine according to any one of claims 1 to 3.

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