JPH0535250B2 - - 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 boost pressure control devices, and particularly to measures for improving acceleration while ensuring engine reliability and durability.

(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

Conventionally, in such a supercharged engine, maximum boost pressure control for controlling the maximum boost pressure downstream of the supercharger has been carried out, for example, as disclosed in Japanese Patent Laid-Open No. 57-146023. By installing a device and controlling the maximum boost pressure downstream of the turbocharger to the set value,
This is intended to effectively improve the charging efficiency and output while ensuring reliability and durability of the engine by preventing damage to the engine due to an abnormal increase in supercharging pressure.

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 engine accelerates when the engine throttle valve opens beyond a predetermined opening degree, the maximum boost pressure downstream of the supercharger is set in advance within a range that can reliably prevent engine damage. By increasing the value for a predetermined period of time and controlling it to a higher value than in normal times (set value),
Efforts are being made to improve the acceleration performance of engines.

(Problem to be Solved by the Invention) By the way, when setting the predetermined period for increasing the maximum supercharging pressure as described above, for example, when the acceleration performance is good and the acceleration time is short, such as when accelerating at a low gear, If the above predetermined period is set short assuming that Since the pressure will drop and return to the set value, it will not be possible to effectively improve the acceleration performance. In other words, if the above predetermined period is set to be long according to the acceleration time at a high gear, during acceleration operation at a low gear with a short acceleration time, the maximum overspeed will continue until the predetermined period has elapsed even after reaching the high rotation range. Since the supply pressure is controlled to increase, this is unfavorable from the viewpoint of engine reliability and durability.

Also, when setting the increase value of the maximum boost pressure, if the increase value is set low assuming a case where the gear ratio is large and does not require much driving force, such as when accelerating at a low gear, While acceleration performance cannot be expected to improve much when accelerating at high gears where the gear ratio is small and requires large driving force, on the other hand, if the above increase value is set high to match the driving force at high gears, During accelerated operation, the driving force becomes excessive, causing problems with engine reliability and durability.

The present invention has been made in view of the above, and its purpose is to increase the maximum boost pressure for a predetermined period of time compared to normal times when the engine accelerates as described above. By changing the increase control periodically or quantitatively depending on the shift position of the transmission, good acceleration performance can always be obtained regardless of the shift position of the transmission while ensuring engine reliability and durability. There is a particular thing.

(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. In a supercharging pressure control device for a supercharged engine, which includes a maximum supercharging pressure control device 13 for controlling the maximum boost pressure downstream of the supercharger 6 to a set value, an acceleration state of the engine is detected. The acceleration detecting means 26, the shift position detecting means 22 that detects the shift position of the transmission, and the output of the acceleration detecting means 26, make the maximum supercharging pressure higher than the set value for a predetermined period, and detect the shift position. In response to the output 22 of the means, at least one of the predetermined period or the maximum boost pressure is set according to the shift position of the transmission, and the higher the shift position of the transmission, the longer the predetermined period or the higher the maximum boost pressure. The supercharging pressure adjusting means 27 is provided to adjust the supercharging pressure so as to change the supercharging pressure.

(Function) With the above configuration, in the present invention, when the engine accelerates, the maximum boost pressure downstream of the supercharger is controlled to rise above the set value for a predetermined period of time, and the control to increase the maximum boost pressure is controlled by the transmission. By changing the control time or the control increase value according to the shift position, in other words, the higher the shift position, the greater the driving force required for acceleration, the worse the acceleration performance, and the longer the acceleration time. The higher the shift position, the longer the predetermined period or the higher the maximum supercharging pressure, thereby obtaining good acceleration performance depending on the shift position.

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

FIG. 2 shows an embodiment of the present invention, in which 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, and 4 is an intake passage. A throttle valve 2 is provided to adjust the amount of intake air, and 5 is a surge tank provided downstream of the throttle valve 4 in the intake passage 2.

6 is an exhaust turbo type supercharger, and the supercharger 6 includes a turbine 6a interposed in the exhaust passage 3;
A shaft 6 is interposed in the intake passage 2 and connected to the turbine 6a.
The compressor 6b is driven by a turbine 6a rotated by the exhaust gas flow, and the intake air is supercharged to the engine 1 by the rotational drive of the compressor 6b. This is what I did.

The exhaust passage 3 is provided with a bypass passage 7 that bypasses the turbine 6a of the supercharger 6, and the bypass passage 7 is provided with a waste gate valve 8 that opens and closes 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 stress-responsive diaphragm device, and includes a diaphragm 9a linked to the wastegate valve 8, and the diaphragm 9.
Pressure chamber 9b and atmospheric chamber 9 divided by a
c, and a spring 9d that is compressed within the atmospheric chamber 9c and biases the wastegate valve 8 in the closing direction. The pressure chamber 9b is connected to the intake passage 2 downstream of the compressor 6b of the supercharger 6 and upstream of the throttle valve 4 via a boost pressure communication passage 10, and is connected to the intake passage 2 downstream of the compressor 6b of the supercharger 6, and is connected to the intake passage 2 downstream of the compressor 6b of the supercharger 6 (compressor 6b). is introduced into the pressure chamber 9b, while the atmosphere communication passage 11 and the air filter 1 provided at the tip opening of the atmosphere communication passage 11 are introduced into the pressure chamber 9b.
2, and the pressure chamber 9b is opened to the atmosphere. Therefore, when the boost pressure downstream of the supercharger 6 (compressor 6b) is introduced into the pressure chamber 9b of the wastegate actuator 9 through the boost pressure communication passage 10, the diaphragm 9a acts under the biasing force of the spring 9d. biasing the waste gate valve 8 against the
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. The boost pressure downstream of the supercharger 6 (compressor 6b) is reduced. 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 closed by the biasing force of the spring 9d and the bypass passage 7 is closed, so that the entire flow of exhaust gas flows to the turbine 6a of the supercharger 6, and supercharging is achieved by suppressing the rotation of the turbine 6a. A wastegate type maximum boost pressure control device 13 is configured to stop and increase the decrease in boost pressure downstream of the turbocharger 6, and thereby control the maximum boost pressure downstream of the turbocharger 6. It is configured.

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 the control unit 16 so that signals can be sent and received. The control unit 16
There is a rotation speed sensor 1 that detects the engine rotation speed.
7. Water temperature sensor 18 that detects engine temperature based on engine cooling water temperature, intake temperature sensor 19 that detects intake air temperature, throttle opening sensor 20 that detects the opening of throttle valve 4, downstream of supercharger 6 (compressor 6b) a pressure sensor 21 that detects the pressure (supercharging pressure) in the intake passage 2 upstream of the throttle valve 4;
Detection signals from a shift position sensor 22 as shift position detection means for detecting the shift position of the transmission are also input. These sensors 17-2
The control unit 16 controls the operation of the first and second control valves 14 and 15 based on the signal No. 2.
The maximum boost pressure downstream of the supercharger 6 (compressor 6b) is feedback-controlled to a target boost pressure (set value) depending on the engine operating state. 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 is advantageous because the boost pressure will be controlled to lower the boost pressure in the event of a failure in the control system. This is preferable in terms of ensuring the reliability of the engine 1. Further, when controlling the boost pressure, a signal from an air flow sensor that detects the amount of intake air may be used in place of the throttle opening sensor 20, or a signal from an air flow sensor may be used in place of the pressure sensor 21. .

In addition, upstream of the first control valve 14 of the boost pressure communication passage 10, the boost pressure (for example, 500 mmHg) downstream of the introduced supercharger 6 is reduced to create a pressure chamber 9b of the waste gate actuator 9. A pressure regulating valve 23 is provided to adjust the supercharging pressure applied to the pump to a substantially constant value (for example, 200 mmHg). Furthermore, 24 and 2
Reference numeral 5 designates orifices provided in the boost pressure communication passage 10 and the atmosphere communication passage 11, respectively. Both orifices 24 and 25 are used to improve the stability of the pressure transmission action by narrowing the passage area of each communication passage 10 and 11. The caliber is set to an appropriate diameter taking into account safety and prevention of overshoot.

Next, the operation of the control unit 16 will be explained based on the operation flow shown in FIGS. 3 and 4. First, in the basic flowchart of boost pressure control shown in Figure 3, start and step
At S ₁ , the engine rotation speed N from the rotation speed sensor 17 and the engine cooling water temperature from the water temperature sensor 18
T _W , the intake air temperature Ta from the intake air temperature sensor 19, the throttle opening θ from the throttle opening sensor 20, and the shift position TM from the shift position 22 are input, and in step _S2 , these signal data are Based on this, the target supercharging pressure P _D is calculated using the following formula.

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

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 proportional control in the duty ratio control of the control valves 14 and 15 is expressed as t _P = PG x (Pa - P _D )
(PG: proportional gain), and in step _S5 , the current actual boost pressure Pa(n)
Based on the difference between and the previous actual boost pressure Pa (n-1), the pulse width t _D is also determined by differential control, t _D = DG×
Formula of {Pa(n)-Pa(n-1)} (DG: differential gain)
Calculated by These pulse widths are determined in step _S6 .
The control pulse width t (=t _P +t _D ) is calculated by adding t _P and t _D .

Next, in step _S7 , the actual supercharging pressure Pa and the target supercharging pressure _PD are compared and determined in order to determine the control direction. If Pa-P _D > 0 (YES), step S ₈ By driving the first control valve 14, the boost pressure downstream of the turbocharger 6 is regulated to a constant pressure with the pressure regulating valve 23, and the maximum boost pressure is set. In addition to the control device 13 (pressure chamber 9b of wastegate actuator 9), it also controls to reduce the actual boost pressure Pa to the target boost pressure _PD . On the other hand, when Pa-P _D <0 (NO), the second control valve 15 is driven in step _S9 to open the maximum boost pressure control device 13 (pressure chamber 9b of the wastegate actuator 9) to the atmosphere. Then, 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.

On the other hand, during acceleration operation, the maximum boost pressure is maintained at the above target boost pressure for a predetermined period of time in order to improve acceleration performance.
In order to correct the acceleration to be higher than _PD , an operation based on the acceleration correction subroutine shown in FIG. 4 is performed. This acceleration correction subroutine is called and executed between step _S1 and step _S2 of the flow of the basic boost pressure control. That is, in step Sa, it is determined whether the acceleration flag is "1" or not, and when the acceleration flag = 1 (YES), it is determined that the acceleration is being corrected and the process immediately moves to step Se. When the answer is NO, it is determined that acceleration correction is not being performed and the process moves to step Sb.
In step Sb, it is determined whether the throttle opening θ is larger than a predetermined value _C1 and whether the rate of change dθ/dt of the throttle opening is larger than a predetermined value _C2 . Either of these determinations is small
If NO, it is determined that the acceleration correction conditions are not satisfied, and the process immediately proceeds to step Si, where it is determined whether or not the maximum boost pressure correction coefficient C _A cc(n) is the basic value "1". Then, if C _A cc(n)=1 and YES, the process ends, and when C _A cc(n)≠1 and NO, step Sh
Move to.

On the other hand, the discrimination in step Sb above is both large.
If YES, it is determined that the acceleration correction condition is satisfied, and the acceleration flag is set to "1" in step Sc.Then, in step Sd, the engine rotation is adjusted from Map(N) in order to increase the maximum boost pressure for a predetermined period of time. The maximum supercharging pressure correction coefficient C _A cc corresponding to the number N is read, and the correction time T _A cc corresponding to the shift position of the transmission is read from the map (TM). Here, the above Map (TM) shows that the higher the shift position, the longer the correction time T _A cc.For example, 10 seconds in 1st gear, 12 seconds in 2nd gear, 15 seconds in 3rd gear, etc. It is set to 20 seconds in 4th gear. Then step
In Se, the correction time T _A cc (n) is gradually decreased by subtracting "1" at a time, and step Sf determines whether T _A cc has become "0" or not, and determines whether T _A cc≠0. NO.
When , go back and repeat the above operation to get T _A cc
Wait until =0. And YES with T _A cc = 0
Then, after setting the acceleration flag to "0" in step Sg, the correction coefficient C _A cc(n) is subtracted by a constant value C ₃ in steps Sh, and the acceleration correction coefficient is gradually decreased at a constant gradient. , the acceleration correction is controlled so as to be completed without causing a torque shock.

Therefore, step Sb of the acceleration correction subroutine
By determining θ>C ₁ and dθ/dt>C ₂ in
An acceleration detection means 26 is configured to detect the acceleration state of the engine 1. Furthermore, when the acceleration state of the engine is detected in step Sb of the acceleration correction subroutine, the target supercharging pressure P _D is increased by the maximum supercharging pressure correction coefficient C _A cc in steps Sd to Sf, and this correction time T A supercharging pressure adjusting means 27 is configured such that _A cc is made longer as the shift position becomes higher in accordance with the shift position of the transmission.

Therefore, in the above embodiment, the maximum boost pressure downstream of the supercharger 6 during engine acceleration is adjusted by the correction coefficient C _A
Since the boost pressure is raised by cc for a predetermined period (correction time T _A cc) above the target boost pressure (set value), acceleration performance can be improved without affecting the reliability of the engine 1. can.

Furthermore, at this time, the correction time T _A cc, which is the maximum boost pressure increase control time, is set to be longer as the shift position of the transmission is higher, so that the acceleration is reduced when accelerating at a lower gear. The acceleration time is good _and the acceleration time is short, and when accelerating at a high gear, the acceleration performance is poor and the acceleration time is long. While ensuring reliability and durability, it is possible to always obtain good acceleration performance regardless of the shift position.

In the above embodiment, the higher the shift position of the transmission is, the longer the correction time T _A cc is. However, by increasing the correction coefficient C _A cc for the maximum boost pressure, The increase value of the maximum supercharging pressure may be increased. In that case, the increase value of the maximum boost pressure corresponds to the acceleration driving force at each shift position, and similarly good acceleration performance can be obtained at each shift position. Further, it is also possible to use both of them, that is, to increase both the correction time T _A cc and the correction coefficient C _A cc as the shift position becomes higher, which is preferable because acceleration performance can be further improved.

Further, the present invention is not limited to the above embodiments, but also includes various other modifications. For example, in each of the above embodiments, the boost pressure control is performed by feedback control based on the detection of the actual boost pressure, but in combination with this, position feedback control is performed by the opening degree of the waste gate valve 8. You can do it like this.

Further, in the above embodiment, an exhaust turbo type supercharger is used as an example of the supercharger for intake supercharging, but other known superchargers such as a pump type supercharger can be used.
Further, in the above embodiment, a waste gate type was described as the maximum boost pressure control device for controlling the boost pressure downstream of the turbocharger, but the present invention
It is also applicable to various other systems such as a relief system that directly controls the boost pressure downstream of the turbocharger.

(Effects of the Invention) As explained above, according to the supercharging pressure control device for a supercharged engine of the present invention, the maximum supercharging pressure increase control is performed by shifting the maximum supercharging pressure during acceleration operation according to the shift position of the transmission. Changes have been made so that the higher the position, the longer the control time or the higher the control increase value, so while ensuring engine reliability and durability,
Good acceleration performance can always be obtained regardless of the shift position of the transmission, and acceleration performance can be further improved.

[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.
4 to 4 illustrate 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 flowchart for explaining the basic operation of the control unit. It is a flowchart diagram explaining a subroutine. DESCRIPTION OF SYMBOLS 1...Engine, 2...Intake passage, 6...Supercharger, 8...Wastegate valve, 13...Maximum boost pressure control device, 16...Control unit, 2
2...Shift position sensor (shift position detection means),
26...Acceleration detection means, 27...Supercharging pressure adjustment 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 supercharging pressure control device for an engine equipped with an engine includes an acceleration detecting means for detecting an acceleration state of the engine, a shift position detecting means for detecting a shift position of a transmission, and a maximum supercharging for a predetermined period based on the output of the acceleration detecting means. the pressure is made higher than the set value, and in response to the output of the shift position detection means, depending on the shift position of the transmission, at least one of the predetermined period or the maximum supercharging pressure is set so that the shift position of the transmission is in a high gear. A supercharging pressure control device for a supercharged engine, comprising: supercharging pressure adjusting means for changing the predetermined period to lengthen the predetermined period or to increase the maximum supercharging pressure.