JPH04241736A - Supercharging pressure control method of turbocharger - Google Patents

Abstract

PURPOSE:To improve drivability at the time of rapid acceleration and prevent excessive force to an engine and a turbocharger by appropriately adjusting an overshoot quantity of supercharging pressure in the case when the supercharging pressure of the turbocharger fixed to the engine of an automobile, etc., is controlled to the target supercharging pressure. CONSTITUTION:An actuator 8 for opening and closing a waste gate valve 7 of a turbocharger 1 is controlled by an opening/closing control valve 11, and an overshoot quantity of supercharging pressure is detected at the time of rapid acceleration. A controlled timing of the controlled pressure introduced in an actuator 8 is adjusted so as to control the supercharging pressure by varying a judging value of the supercharging pressure at the time of the rapid acceleration based on the detected result.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the boost pressure of a turbocharger, which can be suitably applied to automobiles and the like.

0002

[Prior Art] In a turbocharger installed in an automobile engine, a diaphragm type actuator is actuated by boost pressure, and the actuation causes an exhaust gas to be turned on.
Generally, a wastegate valve in an exhaust bypass passage arranged in parallel with the bottle is opened to prevent the supercharging pressure from rising above a set pressure. However, with just this, there is a problem that as the engine rotation approaches the maximum speed, the charging efficiency of the air supply decreases, and the output torque tends to decrease.

[0003] Therefore, an on-off control valve is provided that intermittently opens the diaphragm chamber of the actuator to the atmosphere, and the duty ratio of the on-off operation of this on-off control valve is determined by a fee based on the supercharging pressure detection result. There is a system in which the control pressure introduced into the diaphragm chamber is adjusted by changing it by back-back control, and the supercharging pressure is converged to a required target supercharging pressure. Some engines have a throttle interposed between the opening/closing control valve and the intake passage.

[0004] However, in a system in which the boost pressure is feedback-controlled, when the accelerator pedal is suddenly depressed and sudden acceleration is performed, the auto-boost due to the control delay occurs.
Bar shoot may occur, causing the boost pressure to significantly exceed the target boost pressure, albeit temporarily. Therefore, if such a situation occurs frequently, there is a problem in that it adversely affects the durability of the turbocharger and engine.

[0005] In order to solve the above-mentioned problems, as a prior art of the present invention, for example, Japanese Patent Laid-Open No. 1535/1983
As shown in Publication No. 23, when sudden acceleration of the engine is detected, feedback control is temporarily stopped and boost pressure is controlled in an open manner to improve control followability. There is something I am doing. In addition, as shown in FIG. 4, the difference between the target boost pressure and the actual boost pressure PM is the judgment value P.
If it is larger than i, the on-off control valve is set to the maximum duty ratio D.
．． If the supercharging pressure PM is controlled at max so that it can rise quickly, and the difference becomes smaller than the judgment value Pi, in other words, the supercharging pressure PM changes from the target supercharging pressure to the judgment value Pi. If the pressure exceeds the value obtained by subtracting the
Set the tee ratio to an intermediate setting value D. After changing the duty ratio in a skip manner up to t, the duty ratio is gradually changed based on the actual supercharging pressure detection result, thereby controlling the supercharging pressure PM to converge to the target supercharging pressure. There is also. Here, when the judgment value Pi is increased, the control timing is advanced, so the amount of overshoot is reduced, but on the other hand, there is a delay in pressure rise near the target boost pressure, and drivability during that period is reduced. . On the other hand, if the judgment value Pi is made smaller, the control timing is delayed, so that the boost pressure PM can be quickly raised to the target boost pressure, but the overshoot amount becomes larger. There is a dilemma of putting it away. Therefore, when such boost pressure control is performed, the determination value Pi is determined so as to appropriately suppress the amount of overshoot.

[0006]

[Problem to be Solved by the Invention] However, even if the judgment value is set in this way, the predetermined overflow may not be achieved due to the influence of the diameter of the orifice, the set pressure of the wastegate valve, or changes in these over time. In some cases, the amount of shots cannot be obtained. For example, as shown in FIG. 5, the amount of overshoot varies even within the tolerance of the diameter of the aperture. Specifically, as the orifice diameter becomes smaller, the opening timing of the wastegate valve and the amount of boost pressure relief change, resulting in a larger overshoot amount and a reverse effect. Furthermore, as the diameter of the aperture increases, the amount of overshoot decreases. If the diameter of the aperture further decreases due to aging, the amount of overshoot will further increase. Furthermore, as shown in Fig. 6, if the set pressure of the wastegate valve increases, the valve opening timing when the boost pressure increases is delayed, so the amount of overshoot increases, and conversely, If the set pressure becomes smaller, the valve opening timing is advanced, and the amount of overshoot becomes smaller. therefore,
With the above configuration, variations occur in the amount of overshoot, which adversely affects the durability of the engine and turbocharger, and makes it difficult to reasonably improve drivability.

The object of the present invention is to eliminate all of the above-mentioned problems.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following measures. That is, the turbocharger supercharging pressure control method according to the present invention controls the actuator that opens and closes the wastegate valve of the turbocharger by controlling the duty of the opening/closing control valve. The configuration is such that the boost pressure can be adjusted, and when the difference between the target boost pressure and the actual boost pressure becomes smaller than a judgment value, the duty ratio of the opening/closing control valve is set to an intermediate setting value. This turbocharger controls the boost pressure to the target boost pressure by changing the duty ratio in a skip-like manner based on the actual boost pressure detection results. - A method for controlling supercharging pressure of a turbocharger, characterized in that the determination value is changed in accordance with an amount of overshoot of the supercharging pressure.

[0009]

[Operation] According to such a configuration, if the difference between the target boost pressure and the actual boost pressure is large and exceeds the above-mentioned judgment value, the on-off control valve is set at or near the maximum duty ratio. It will be controlled by the value of . In this case, the actuator closes the wastegate valve to promote the increase in supercharging pressure. When the boost pressure increases and the difference becomes smaller than the determination value, the duty ratio is changed in a skip manner to an intermediate set value, and then the duty ratio is gradually changed. As a result, the amount of exhaust gas bypass is adjusted by the actuator, and the boost pressure is converged to the target boost pressure.

Further, if the amount of overshoot of the boost pressure is larger than a predetermined appropriate level, the value is changed to the side where the above-mentioned judgment value becomes larger. Then, at the next sudden acceleration, the control timing of the boost pressure will be advanced based on the judgment value, so that the overflow at the time of sudden acceleration will be accelerated.
The amount of shots can be reduced to a predetermined appropriate level. Conversely, if the amount of overshoot of the boost pressure is smaller than the appropriate level, the determination value is changed to the smaller side. Therefore, during the next sudden acceleration, the adjustment timing of the boost pressure will be delayed based on the judgment value, making it possible to correct the amount of overshoot to an appropriate level and It becomes possible to quickly raise the pressure to around the target boost pressure.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

1 in the figure is a turbocharger of an automobile engine.
It's Ja. This turbocharger 1 is an exhaust turbo that is rotated by the energy of exhaust gas discharged from an engine.
It is equipped with a bin 2 and a compressor 3 driven by the exhaust turbine 2, and can compress air introduced into the intake passage 5 through the air cleaner 4 and supply it to the engine. It looks like this. Further, a bypass passage 6 is provided for the exhaust turbine 2, and a waste gate valve 7 is disposed in the bypass passage 6, and the waste gate valve 7 is opened and closed by a diaphragm type actuator 8. ing.

The actuator 8 is formed by forming a sealed diaphragm chamber 8b on the back side of a diaphragm 8a that is urged rearward by a pressure regulating spring (not shown), and the actuator 8 is introduced into the diaphragm chamber 8b. When the air pressure exceeds a predetermined value defined by the pressure regulating spring, the diaphragm 8a is deflected and the actuating rod 8c is operated to protrude forward. The wastegate valve 7 is configured to open when the operating rod 8c moves forward. The diaphragm chamber 8b is communicated with the compressor downstream side 5a of the intake passage 5 via a pressure guiding path 9 having a throttle 9a in the middle. In addition, a pressure relief path 10 branched from the middle of this pressure guiding path 9
is communicated with the inside of the air cleaner 4, and an on-off control valve VSV11 is interposed in the middle of this pressure relief passage 10.

The opening/closing control valve VSV11 is connected to the pressure relief passage 10.
A valve body (not shown) that opens and closes the valve is actuated by an electromagnetic actuator, and is switched to the open position only while a driving voltage is applied to the electromagnetic actuator.

The opening/closing control valve VSV11 is opened/closed under duty control by an electronic control unit ECU12. This electronic control unit ECU12 includes a central processing unit (not shown), a memory, and an input interface.
It consists of a microcomputer unit equipped with an input interface and an output interface, and the input interface includes at least a a signal a from the throttle sensor 14, a supercharging pressure signal b from the pressure sensor 16 that detects the pressure in the surge tank 15, an engine rotation signal c indicating engine rotation, and a water temperature signal corresponding to the engine cooling water temperature. d are inputted respectively. A driving pulse voltage is supplied from the output interface to the electromagnetic actuator of the opening/closing control valve VSV11. Note that as the throttle sensor 14, a potentiometer or the like that converts the opening degree of the throttle valve 13 into an electrical signal is used. As the pressure sensor 16, for example, a sensor whose electric capacity changes depending on the pressure difference between the upper and lower sides of a pair of diaphragms and which can obtain an electric signal proportional to the intake pressure is used. The engine rotation signal c is obtained, for example, by calculating the engine rotation speed based on the time interval of ignition pulses output from the ignition device. The water temperature signal d is input from a water temperature sensor (not shown) that includes a built-in thermistor whose resistance value changes depending on the engine cooling water temperature.

The electronic control unit ECU 12 has a built-in program as schematically shown in FIG. First of all,
In step 51, a signal a from the throttle sensor 14,
Input various information such as the boost pressure signal b, engine rotation signal c, and water temperature signal d from the pressure sensor 16, and proceed to step 52.
Proceed to. In step 52, it is determined whether a predetermined feedback execution condition is satisfied. For example, it is determined whether the throttle valve 13 is opened at a predetermined angle (60°deg) or more and whether the engine cooling water temperature is within a predetermined range, and if these execution conditions are met, step 53 is performed. Proceed to. In step 53, a target supercharging pressure PMt corresponding to the engine speed is selected based on a map stored in the memory in advance, and the process proceeds to step 54. In step 54, it is determined whether the difference between the target boost pressure PMt and the actual boost pressure PM (PMt-PM) is smaller than the determination value Pi. If the difference (PMt-PM) is larger than the determination value Pi, the process proceeds to step 55, and if it is smaller, the process proceeds to step 56. In step 55, the duty ratio of the on-off control valve VSV11 is set to the maximum value D. Set to max. In step 56, the duty ratio is set to the maximum value D. m
ax to set value D. After skipping to t, the supercharging pressure P
The on-off control valve VS is placed on the side where M approaches the target supercharging pressure PMt.
The duty ratio of the pulse voltage applied to V11 is gradually changed, and the process proceeds to step 57. In step 57, the overshoot amount is detected, and a learning correction value Px is determined based on the detection result, and the process proceeds to step 58. As shown in FIG. 3, the learning correction value Px is based on the supercharging pressure P
The map is selected from maps stored in memory in advance in accordance with the overshoot amount of M. This learning correction value P
x becomes zero when the overshoot amount is at the appropriate level L, and becomes a positive value when it exceeds the appropriate level L. Further, if the appropriate level L has not been reached, it is set to be a negative value. In step 58, the learned correction value Px is added to the previous judged value Pio to correct the judged value Pi. Note that the corrected judgment value Pi is not erased even if the ignition key is turned off.

According to such a configuration, the target supercharging pressure PM
If the difference between t and the actual supercharging pressure PM (PMt-PM) is larger than the judgment value Pi, the on-off control valve VSV11 is controlled with the maximum duty ratio (steps 51 to 55).
. In this case, a pulse voltage continues to be applied to the electromagnetic actuator of the opening/closing control valve VSV11, and the wastegate valve 7 is closed by the actuator 8, so that the increase in supercharging pressure PM is promoted. When the boost pressure PM increases and the difference (PMt-PM) becomes smaller than the determination value Pi, first, the duty ratio reaches the maximum value D. Setting value halfway from maxD. After being skipped to t, the duty ratio of the pulse voltage applied to the on-off control valve VSV11 is gradually changed so that the boost pressure PM approaches the target boost pressure PMt (step 54→ 56). the result,
The actuator 8 rapidly adjusts the exhaust bypass amount, and the rising speed of the boost pressure PM reaches the target boost pressure P.
It will be rapidly suppressed near Mt.

Further, when the amount of overshoot of the supercharging pressure PM is larger than the appropriate level L, the value is changed to the side where the judgment value Pi becomes larger. Then, during the next sudden acceleration, the control timing of the supercharging pressure PM will be advanced based on the judgment value Pi, so the amount of overshoot during sudden acceleration will be reduced to the appropriate level L. Can be done. Conversely, if the amount of overshoot of supercharging pressure PM is smaller than the appropriate level L, the value will be changed to the side where the judgment value Pi becomes smaller. Therefore, during the next sudden acceleration, the adjustment timing of the supercharging pressure PM will be delayed based on the determination value Pi. As a result, over
The chute amount can be corrected to an appropriate level L, and the supercharging pressure PM can be quickly raised to around the target supercharging pressure PMt.

Therefore, with such a configuration, the opening timing of the wastegate valve 7 and the supercharging pressure may vary due to tolerances such as the diameter of the throttle 9a and the set pressure of the wastegate valve 7, or due to changes in these over time. Even if the amount of relief etc. changes, the amount of overshoot can be corrected and maintained at an appropriate value. As a result, when accelerating, the turbo
It is possible to effectively prevent the engine 1 from overrunning and strain the engine, and also to reasonably improve drivability during acceleration.

Note that the present invention can also be effectively applied to a device that does not have an aperture. In addition, the judgment value of boost pressure is
It may be modified periodically.

[0021]

[Effects of the Invention] With the above configuration, the present invention not only allows supercharging pressure to be controlled according to engine rotation, but also eliminates the possibility of maladjustment in the member for adjusting supercharging pressure. Even if such a problem exists, the boost pressure can be effectively controlled to the target boost pressure. Therefore, when sudden acceleration is performed, strain on the turbocharger and engine can be effectively prevented, and drivability can be reasonably improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart diagram showing one embodiment of the present invention.

FIG. 3 is a diagram showing control setting conditions in an embodiment of the present invention.

FIG. 4 is an action explanatory diagram showing a conventional example.

FIG. 5 is a diagram for explaining a problem in the conventional example.

FIG. 6 is a diagram for explaining a problem in the conventional example.

[Explanation of symbols]

1...Turbo charger 2...Exhaust turbine 3...Compressor 6...Bypass passage 7...Wastegate valve 8...Actuator 11...Opening/closing control valve 12...Electronic control device Pi…judgment value

Claims (1)

[Claims] Claim 1: The present invention is constructed so that supercharging pressure can be adjusted by controlling an actuator that opens and closes a wastegate valve of a turbocharger by controlling the duty of an opening/closing control valve. When the difference between the target boost pressure and the actual boost pressure becomes smaller than the judgment value, the duty ratio of the on-off control valve is changed in a skip manner to an intermediate set value, and then the duty ratio is changed. A turbocharger supercharging pressure control method in which the supercharging pressure is feedback-controlled to a target supercharging pressure by gradually changing the supercharging pressure based on the actual supercharging pressure detection result, the method comprising: 1. A turbocharger supercharging pressure control method, characterized in that the value is changed in accordance with the amount of supercharging pressure overshoot.