JPH0530971B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a supercharged engine in which the maximum boost pressure downstream of the supercharger is controlled to a set value. The present invention relates to a boost pressure control device, and particularly relates to one that controls the maximum boost pressure to be higher than the set value when an engine acceleration is requested.

(Prior Art) Conventionally, a supercharger is installed in the intake passage of an engine, and the intake air is supercharged by the supercharger in order to improve the filling efficiency of the engine intake air and increase the output. It is widely known that In addition, in such a supercharged engine, a maximum boost pressure control device is installed to control the maximum boost pressure downstream of the supercharger to a set value, and the maximum boost pressure downstream of the turbocharger is adjusted to a set value. By suppressing the increase in supercharging pressure, damage to the engine due to an abnormal increase in supercharging pressure can be prevented, and the above-mentioned charging efficiency and output can be effectively improved while ensuring reliability and durability of the engine. is known.

By the way, conventionally, in such a supercharging pressure control device for a supercharged engine, for example, Japanese Patent Application Laid-Open No. 57-1999
As disclosed in Publication No. 157017, when the throttle valve opens beyond a predetermined opening degree when the engine accelerates, the maximum boost pressure downstream of the supercharger is set in advance within a range that can reliably prevent engine damage. Increase the temperature for a predetermined period of time, and set this value in normal conditions (set value).
In other words, the acceleration performance of the engine is improved by controlling the boost pressure to be higher than the boost pressure, that is, by performing acceleration correction of the boost pressure.

(Problem to be Solved by the Invention) By the way, in the above-mentioned conventional system, the time for acceleration correction of boost pressure (maximum boost pressure increase control) is fixed at a predetermined time. The boost pressure may be adjusted depending on the length of the acceleration request time. There is a problem that acceleration correction cannot be performed appropriately. Further, since the value of the rate of increase in the engine rotational speed corresponding to the acceleration request state differs for each shift position of the transmission, it is also necessary to accurately grasp the acceleration request state for each shift position.

Therefore, the present invention has been made in view of the above points, and its purpose is to accurately detect the acceleration request state of the engine at all times and for each shift position, and to always maintain the boost pressure at the time of the acceleration request. By performing acceleration correction, that is, controlling the increase in the maximum boost pressure, the acceleration correction of the boost pressure can always be performed satisfactorily regardless of the length of the required acceleration time, thereby reliably improving acceleration performance.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the present invention includes a supercharger 6 interposed in the intake passage 2 for intake supercharging, as shown in FIG. , and a maximum boost pressure control device 13 for controlling the maximum boost pressure downstream of the supercharger 6 to a set value. And intake passage 2
Throttle opening degree detection means 20 detects the opening degree of the throttle valve 4 provided in
In response to the outputs of the throttle opening degree detection means 20 and engine speed change rate detection means 26, when the opening degree of the throttle valve is at least a predetermined value and the rate of increase in the engine speed is at least a predetermined threshold value, the maximum excess is detected. The supercharging pressure adjusting means 27 increases the supply pressure above the set value. Further, a shift position detecting means 22 detects the shift position of the transmission, and a threshold value for the rate of increase in the engine rotational speed is changed in the supercharging pressure adjusting means 27 based on the output of the shift position detecting means 22. The threshold value changing means 28 is provided to change the threshold value according to the shift position of the machine.

(Function) With the above configuration, in the present invention, when an acceleration request is made when the throttle opening is at least a predetermined value and the rate of increase in the engine speed (or the corresponding vehicle speed) is at least a predetermined threshold, the supercharger is By increasing the maximum boost pressure of the engine by a predetermined amount above the normal state (set value), the control to increase the maximum boost pressure, that is, the acceleration correction of the boost pressure, always responds favorably to the acceleration request of the engine. I can do it. Moreover, since the threshold value for the rate of increase in engine speed is changed according to the shift position of the transmission, the acceleration request state at each shift position can be accurately and appropriately determined and unnecessary acceleration correction can be made. Never.

It should be noted that the above-mentioned acceleration request state is a special operating condition and occurs relatively infrequently, so there is no problem in terms of engine reliability.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. 2 and the following drawings.

In FIG. 2, 1 is an engine, 2 is an intake passage for supplying intake air to the engine 1, 3 is an exhaust passage for discharging exhaust gas from the engine 1,
4 is a throttle valve disposed in the intake passage 2 to adjust the amount of intake air; 5 is a surge tank disposed downstream of the throttle valve 4 in the intake passage 2.

6 is an exhaust turbo supercharger. The supercharger 6
A turbine 6a interposed in the exhaust passage 3 and a shaft 6c connected to the turbine 6a interposed in the intake passage 2.
Compressor (blower) connected to drive via
6b, the compressor 6b is driven by the turbine 6a rotated by the exhaust gas flow,
The engine 1 is supercharged with intake air by rotationally driving the compressor 6b.

The exhaust passage 3 is provided with a bypass passage 7 that bypasses the turbine 6a of the supercharger 6. A waste gate valve 8 for opening and closing the bypass passage 7 is disposed in the bypass passage 7,
The wastegate valve 8 is controlled to open and close by a wastegate actuator 9. The wastegate actuator 9 is composed of a pressure-responsive diaphragm device, and includes a diaphragm 9a linked to the wastegate valve 8, a pressure chamber 9b and an atmospheric chamber 9c partitioned by the diaphragm 9a, and an atmospheric chamber 9c. The wastegate valve 8 is provided with a spring 9d that biases the wastegate valve 8 compressed in the chamber 9c in the valve-closing direction. The pressure chamber 9b has a supercharging pressure communication passage 10
is connected to the intake passage 2 downstream of the compressor 6b of the supercharger 6 and upstream of the throttle valve 4,
The supercharging pressure downstream of the supercharger 6 (compressor 6b) is introduced into the pressure chamber 9b, and is communicated with the atmosphere via an atmosphere communication passage 11 and an air filter 12 provided at the tip opening of the atmosphere communication passage 11, Pressure chamber 9
b is exposed to the atmosphere. However,
Pressure chamber 9 of the wastegate actuator 9
When the supercharging pressure downstream of the supercharger 6 (compressor 6b) is introduced into the supercharger 6 (compressor 6b) through the supercharging pressure communication passage 10, the diaphragm 9a is biased against the urging force of the spring 9d, and the waste gate valve 8 is biased. By opening the bypass passage 7, a part of the exhaust gas flow bypasses the turbine 6a of the supercharger 6 and flows down, thereby suppressing the rotation of the turbine 6a and the rotation of the compressor 6b. This reduces the supercharging pressure downstream of the supercharger 6 (compressor 6b). On the other hand, when the pressure chamber 9b is opened to the atmosphere through the atmosphere communication passage 11, the waste gate valve 8 is actuated to close by the biasing force of the spring 9d, closing the bypass passage 7, so that the entire flow of exhaust gas is prevented. Turbine 6 of supercharger 6
a, the decrease in the boost pressure downstream of the supercharger 6 due to the rotation suppression of the turbine 6a is stopped and controlled to increase, thereby increasing the maximum boost pressure downstream of the supercharger 6 to the set value. A wastegate type maximum boost pressure control device 13 is configured to control the maximum boost pressure.

Furthermore, a first control valve 14 for controlling opening and closing of the boost pressure communication passage 10 is interposed in the middle of the boost pressure communication passage 10, and a first control valve 14 is provided in the middle of the atmosphere communication passage 11. A second control valve 15 that controls opening and closing is provided. Both control valves 14,1
5 is connected to a control unit 16 which controls the operation of both control valves 14 and 15 so that signals can be sent and received. The control unit 16 includes a rotation speed sensor 17 that detects the engine rotation speed, a water temperature sensor 18 that detects the engine temperature based on the engine cooling water temperature, and an intake air temperature sensor 1 that detects the intake air temperature.
9. Throttle opening sensor 2 as a throttle opening detection means for detecting the opening of the throttle valve 4
0, a pressure sensor 21 that detects the pressure (supercharging pressure) in the intake passage 2 downstream of the supercharger 6 (compressor 6b) and upstream of the throttle valve 4, and a shift sensor 21 that detects the shift position of the transmission. Each detection signal of the position sensor 22 is input.
Here, it is preferable in terms of control accuracy that each of the control valves 14 and 15 be constructed as a duty solenoid valve, but they may also be constructed as a proportional solenoid valve. Furthermore, using a normally open first control valve 14 and a normally closed second control valve 15 means that
In the event of a failure in the control system, the boost pressure is controlled to lower the boost pressure, which is preferable in terms of ensuring the reliability of the engine 1. Furthermore, when controlling the boost pressure, a signal from an air flow sensor that detects the amount of intake air may be used instead of the throttle opening sensor 20, or a signal from an air flow sensor may be used instead of the pressure sensor 21. .

In addition, the first control valve 1 of the boost pressure communication passage 10
4 upstream is the supercharging pressure downstream of the turbocharger 6 (e.g. 500
A pressure regulating valve 23 is provided to adjust the supercharging pressure applied to the pressure chamber 9b of the wastegate actuator 9 to a substantially constant value (for example, 200 mmHg) by introducing a reduced pressure (mmHg). Note that 24 and 25 are orifices provided in the boost pressure communication passage 10 and the atmosphere communication passage 11, respectively, and both orifices 2
4 and 25 are set to appropriate diameters in view of ensuring good stability of the pressure transmission action and preventing overshoot by narrowing the passage area of each communication passage 10 and 11.

Next, the control of the first and second control valves 14 and 15 by the control unit 16 will be explained based on the operational flow shown in FIGS. 3 and 4. First, in the basic flowchart _of boost pressure control shown in FIG.
Engine coolant temperature Tw from water temperature sensor 18,
The signal data of the intake air temperature Ta from the intake air temperature sensor 19 and the throttle opening degree θ from the throttle opening degree sensor 20 are input, and in step _S2 , the target supercharging pressure P _P is calculated using the following formula based on these signal data. Calculated by

P _D =K×P _B ase Here, K is a correction coefficient and is determined by the engine coolant temperature Tw, intake air temperature Ta, acceleration correction amount, etc.

Next, in step _S3 , signal data of the actual supercharging pressure Pa is input from the pressure sensor 21. Then, in step _S4 , the first and second boost pressures described below are determined based on the difference between the actual boost pressure Pa and the target boost pressure P _D.
The pulse width t _P due to the proportional control in the duty ratio control of the control valves 14 and 15 is expressed as t _P = PG x (Pa - P _D )
It is calculated using the formula (PG: proportional gain), and the current actual boost pressure Pa is calculated in step _S5 .
Based on the difference between (n) and the previous actual boost pressure Pa (n-1), the pulse width t _D is also calculated by differential control, t _D =
Calculated using the formula DG x {Pa(n)-Pa(n-1)} (DG: differential gain), and in step _S6 add these pulse widths _tP and _tD to obtain the control pulse width t(= t _P +
_tD ).

Next, in step _S7 , the actual supercharging pressure Pa and the target supercharging pressure P _D are compared and determined in order to determine the control direction, and if Pa-P _D >0 (YES), _the By driving the 1 control valve 14, the supercharging pressure downstream of the supercharger 6 is regulated to a constant pressure by the pressure regulating valve 23, and the maximum supercharging pressure control device 13, that is, the pressure chamber 9b of the waste gate actuator 9.
In addition, the actual supercharging pressure Pa is controlled to be reduced to the target supercharging pressure P _D , and when Pa-P _D < 0 (NO), the second control valve 15 is driven in step _S9 to reduce the waste gate. The pressure chamber 9b of the actuator 9 is opened to the atmosphere, the actual supercharging pressure Pa is controlled to increase to the target supercharging pressure _PD , and thereafter, the process returns to step _S1 and repeats the same control operation. Therefore, the control unit 16 controls the opening and closing of the first and second control valves 14 and 15 based on the basic supercharging pressure control flow shown in FIG. 3, thereby controlling the operation of the wastegate actuator 9.
The maximum boost pressure downstream of the supercharger 6 is feedback-controlled to a set value (target boost pressure).

On the other hand, when acceleration is requested, an operation based on the acceleration correction subroutine shown in Fig. 4 is performed to correct the maximum boost pressure to be higher than the target boost pressure P _D in order to improve acceleration performance. . This acceleration correction subroutine is called and executed between step _S1 and step _S2 of the basic boost pressure control flow. That is, step
At Sa, it is determined whether the throttle opening θ is larger than a predetermined value _C1 . If θ> _C1 is YES, the process proceeds to step Sb, where the transmission shift position signal is sent from the shift position sensor 22. Based on the map shown in FIG. 5, a predetermined threshold value _C2 of the rate of increase in the engine speed corresponding to the acceleration request state at the current shift position is read. Then step
Actual engine speed increase rate of change dN/dt in Sc
This dN/dt is the predetermined threshold value C ₂
Determine whether it is larger than dN/dt＞C ₂ YES
When , it is determined that the acceleration correction condition is satisfied, and
Proceed to step Sd, read the maximum boost pressure correction coefficient C _ACC (n) according to the engine speed from the map Map (N) in order to increase the maximum boost pressure, and achieve the target supercharging with the correction coefficient C _ACC . Correct the pressure P _D and end.

On the other hand, if the determination in step Sa is NO with θ≦C ₁ , or if the determination in step Sc is dN/dt≦
In the case of NO in _C2 , it is determined that the acceleration correction conditions are not satisfied, and the process immediately proceeds to step Se.
The maximum boost pressure correction coefficient C _ACC (n) is the basic value “1”
If C _ACC (n) = 1, YES, the process ends; if C _ACC ≠ 1, NO, the process moves to step Sf, and the correction coefficient C _ACC (n) is set to a constant value C ₃ The acceleration correction coefficient is gradually decreased at a constant gradient by subtracting the acceleration correction coefficient, thereby completing the acceleration correction without causing a torque shock.

Therefore, step Sc of the acceleration correction subroutine
The engine speed change rate detection means 26 is configured to detect the change rate of the engine speed by calculating dN/dt in . In addition, steps Sa, Sc, and Sd of the same subroutine are used to detect the throttle opening detection means (strottle opening sensor 2).
0), the throttle opening degree detected by 0) is equal to or higher than a predetermined value _C1 corresponding to a substantially fully open state, and the rate of increase in engine rotation speed dN/dt detected by the engine rotation rate change detection means 26 is a predetermined threshold. value
When the target supercharging pressure P D is higher than C ₂ , the supercharging pressure adjusting means 27 is configured to increase the target supercharging pressure P _D by using the correction coefficient C _ACC of the maximum supercharging pressure. moreover,
Test Sb of the same subroutine changes the threshold value C ₂ of the rate of increase in engine speed in the supercharging pressure adjusting means 27 according to the shift position of the transmission, and sets the acceleration request state at each shift position. Threshold changing means 28 is configured to set the corresponding threshold _C2 .

Therefore, in the above embodiment, when the throttle opening is almost fully open at a predetermined value or more and the rate of increase in engine speed is higher than a predetermined threshold value and an acceleration request is made, the target supercharging pressure P _D is adjusted by the correction coefficient. The maximum boost pressure downstream of the turbocharger 6 is controlled to be higher than the set value (target boost pressure P _D ) due to the increase correction by C _ACC , and therefore the boost pressure is adjusted according to the acceleration request. Acceleration correction (maximum supercharging pressure increase control) is performed appropriately and good acceleration performance is obtained.

In addition, the threshold value of the rate of increase in engine speed for determining the above-mentioned acceleration request state has been changed according to the shift position of the transmission, so the acceleration request state at each shift position can be accurately and appropriately determined. I can,
No unnecessary acceleration correction is performed.

In the above embodiment, the engine speed change rate detecting means 26 is configured to directly detect dN/dt, but instead of this, the change rate of the engine speed is indirectly detected by detecting the change rate of the vehicle speed. You can do it like this.

Further, the present invention is not limited to the above embodiments, but also includes various other modifications. For example, in the above embodiment, the maximum boost pressure is controlled by feedback control based on the detection of the actual boost pressure. You may also do so.

Furthermore, in the above embodiment, an exhaust turbo type supercharger was used as an example of the supercharger for intake supercharging, but
Other known superchargers such as a pump type supercharger can also be used. Further, in the above embodiment, a wastegate type maximum boost pressure control device was described for controlling the maximum boost pressure downstream of the turbocharger to a set value (target boost pressure), but the present invention , and other various systems such as a relief system that directly controls the maximum boost pressure downstream of a turbocharger.

(Effects of the Invention) As explained above, according to the supercharging pressure control device for a supercharged engine of the present invention, when the throttle opening is equal to or greater than a predetermined value and the rate of increase in engine speed is equal to or greater than a predetermined threshold value, When an acceleration request is made above, the maximum boost pressure downstream of the turbocharger is increased above the set value to perform acceleration correction of the boost pressure, and the engine speed is adjusted to determine the acceleration request state. Since the threshold value of the increase rate of change is changed according to the shift position of the transmission, the acceleration correction of the boost pressure can be made to respond well to the acceleration correction regardless of the length of the engine acceleration request time. In addition to being able to obtain good acceleration performance, it is also possible to accurately and appropriately determine the acceleration request state at each shift position and prevent unnecessary acceleration correction.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
5 to 5 show an embodiment of the present invention, FIG. 2 is a general schematic diagram, FIG. 3 is a flowchart explaining the basic operation of the control unit, and FIG. 4 is a subroutine for acceleration correction. FIG. 5 is a flowchart for explaining the above, and FIG. 5 is a map showing the value of the predetermined rate of increase in engine speed at each shift position. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 4... Throttle valve, 6... Supercharger, 13... Maximum supercharging pressure control device, 20... Throttle opening detection means, 22
...Shift position detection means, 26...Engine rotation rate detection means, 27...Supercharging pressure adjustment means, 28
...Threshold value changing means.

Claims (1)

[Claims] 1. A supercharger equipped with a supercharger installed in an intake passage for intake supercharging, and a maximum boost pressure control device for controlling the maximum boost pressure downstream of the supercharger to a set value. A boost pressure control device for an engine equipped with a throttle valve includes a throttle opening detecting means for detecting the opening of a throttle valve provided in an intake passage, an engine rotation change rate detecting means for detecting a rate of change in engine speed, and a throttle opening detecting means for detecting the opening of a throttle valve provided in an intake passage; When the opening degree of the throttle valve is at least a predetermined value and the rate of increase in engine speed is at least a predetermined threshold value, the maximum supercharging pressure is determined from the above set value. and a shift position detection means for detecting the shift position of the transmission; and a shift position detection means for detecting the shift position of the transmission; 1. A supercharging pressure control device for a supercharged engine, comprising threshold value changing means for changing the threshold value in accordance with a shift position of a transmission.